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THE PALAEONTOLOGICAL ASSOCIATION

The Association was founded in 1957 to promote research in palaeontology and its allied sciences.

COUNCIL 1985-1986

President: Professor C. Downie, Department of Geology, University of Sheffield, Sheffield SI 3JD

Vice-Presidents : Dr. M. G. Bassett, Department of Geology, National Museum of Wales, Cardiff CF1 3NP
Dr. R. Riding, Department of Geology, University College, Cardiff CF1 1XL
Treasurer : Dr. M. Romano, Department of Geology, University of Sheffield, Sheffield SI 3JD
Membership Treasurer. Dr. A. T. Thomas, Department of Geological Sciences, University of Aston, Birmingham B4 7ET
Institutional Membership Treasurer. Dr. A. R. Lord, Department of Geology, University College, London WC1E 6BT
Secretary: Dr. P. W. Skelton, Department of Earth Sciences, Open University, Milton Keynes MK7 6AA
Circular Reporter: Dr. D. J. Siveter, Department of Geology, University of Hull, Hull HU6 7RX
Marketing Manager: Dr. R. J. Aldridge, Department of Geology, University of Nottingham, Nottingham NG7 2RD

Editors

Dr. D. E. G. Briggs, Department of Geology, University of Bristol, Bristol BS8 1RJ
Dr. P. R. Crowther, Leicestershire Museums Service, Leicester LEI 6TD
Dr. D. Edwards, Department of Plant Science, University College, Cardiff CF1 1XL
Dr. L. B. Halstead, Department of Geology, University of Reading, Reading RG6 2AB
Dr. R. Harland, British Geological Survey, Keyworth, Nottingham NG12 5GG
Dr. T. J. Palmer, Department of Geology, University College of Wales, Aberystwyth SY23 2AX

Other Members

Dr. M. J. Benton, Belfast Dr. C. R. C. Paul, Liverpool

Dr. M. E. Collinson, London Dr. A. B. Smith, London

Dr. P. L. Forey, London Professor T. N. Taylor, Columbus

Dr. A. W. Owen, Dundee

Overseas Representatives

Australia: Professor B. D. Webby, Department of Geology, The University, Sydney, N.S.W., 2006
Canada: Dr. B. S. Norford, Institute of Sedimentary and Petroleum Geology, 3303-33rd Street NW., Calgary, Alberta
Japan : Dr. I. Hayami. University Museum, University of Tokyo, Hongo 7-3-1, Bunkyo-Ku, Tokyo
New Zealand: Dr. G. R. Stevens. New Zealand Geological Survey. P.O. Box 30368. Lower Hutt
U.S. A.: Dr. R. Cuffey, Department of Geology, Pennsylvania State University, Pennsylvania
Professor A. J. Rowell, Department of Geology, University of Kansas, Lawrence, Kansas 66045
Professor N. M. Savage, Department of Geology, University of Oregon, Eugene, Oregon 97403
South America: Dr. O. A. Reig, Departamento de Ecologia, Universidad Simon Bolivar, Caracas 108. Venezuela

MEMBERSHIP

Membership is open to individuals and institutions on payment of the appropriate annual subscription. Rates for 1986 are:

Institutional membership
Ordinary membership
Student membership
Retired membership

£45 00 (U.S. $68)
£21 -00 (U.S. $32)
£11-50 (U.S. $18)
£10-50 (U.S. $16)

There is no admission fee. Correspondence concerned with Institutional Membership should be addressed to Dr. A. R. Lord,
Department of Geology, University College, Gower Street, London WC1E 6BT, England. Student members are persons
receiving full-time instruction at educational institutions recognized by the Council. On first applying for membership, an
application form should be obtained from the Membership Treasurer, Dr. A. T. Thomas, Department of Geological Sciences,
University of Aston, Aston Triangle, Birmingham B4 7ET. Subscriptions cover one calendar year and are due each January; they
should be sent to the Membership Treasurer. All members who join for 1986 will receive Palaeontology , Volume 29, Parts 1-4.
All back numbers are still in print and may be ordered from Marston Book Services, P.O. Box 87, Oxford OX4 1 LB, England,
at £21-50 (U.S. $33) per part (post free).

Cover: The chitinozoan Ancyrochitina onniensis Jenkins 1967 from the Late Caradoc, Onnian of the Onny River, Shropshire.
The specimen measures 130 pm in length. Dr. W. A. M. Jenkins provided the photomicrograph.

MOLECULAR PALAEONTOLOGY

by BRUCE RUNNEGAR
(Twenty-eighth annual address, delivered 15 March 1985)

Abstract. Recent developments in molecular biology are beginning to provide new ways of looking at the
history of life. At present there are three main potential sources of information: organic molecules extracted
from rocks or fossils, the comparative molecular biology of living organisms, and the knowledge that is
developing about the role of biopolymers in the construction of skeletons. Each of these fields is reviewed briefly
to illustrate how the information that is becoming available may be used in future to serve the common goals of
palaeontology and molecular biology.

I like to take the catholic view that palaeontology deals with the history of the biosphere and that
palaeontologists should use all available sources of information to understand the evolution of life
and its effect on the planet. Viewed in this way the current advances being made in the field of
molecular biology are as important to present-day palaeontology as studies of comparative anatomy
were to Owen and Cuvier. I appreciate that palaeontologists have just participated in an intellectual
and methodological revolution of the first magnitude (the development of global tectonics from the
unpopular theory of continental drift) and that it is becoming increasingly difficult to develop
interdisciplinary expertise, but the results that are now appearing suggest that molecular biology will
be as important to the whole of biology as an understanding of atomic structure was to the physical
sciences.

This does not mean that palaeontologists must adopt a passive role as educated observers of this
explosion of knowledge. Instead, palaeontologists have the kinds of skills that are required to
develop a general understanding of the experimental results that are flooding the literature at the
present time. Most molecular biologists have limited training in the classical disciplines of biology
and little appreciation of the nature of the fossil record and the dimensions of geological time. Their
remarkable experimental and inductive skills will be strengthened through interactions with scientists
having an expert knowledge of the history of life and the large-scale processes and effects of
evolution.

Needless to say, I am not the first to advocate this approach. Until his untimely death early in 1984,
T. J. M. Schopf was a champion of this cause (Gould 1984). He, more than any other person,
attempted to bridge the gulf between palaeontology and molecular biology— a difficult and
demanding task. At the time of his death we were beginning (at his suggestion) to try to put together
the information from molecular biology that might help understand the early history of the Metazoa.
I shall refer to that study below; the point to be made here is that Tom Schopf was convinced that it
is vital that palaeontologists begin to formulate evolutionary hypotheses that can be tested by
further experiments in molecular biology.

As with palaeontology, I take a catholic view of the field known as molecular palaeontology — a
term used for many years for the study of 'chemical fossils’ and incorporating the subject known as
'palaeobiochemistry’ (Abelson 1956; Sylvester-Bradley 1964; Degens 1967; Eglinton and Calvin
1967; Calvin 1968). When Melvin Calvin delivered the Bennett Lecture at the University of Leicester
on the topic 'Molecular Palaeontology’ in 1968 (Calvin 1968) he dealt only with molecules extracted
from rocks. This approach has proved to be of fundamental importance to the oil industry (Brooks
1981) and to studies of the early history of life (J. W. Schopf 1978), but the term ‘molecular
palaeontology’ can also be far more embracing.

| Palaeontology, Vol. 29, Part 1, 1986, pp. I-24.|

2

PALAEONTOLOGY, VOLUME 29

There are three main areas where molecular biology and palaeontology impinge on each other;
these three areas constitute what I prefer to call ‘molecular palaeontology’. The first is the traditional
field of fossil molecules. The second is the role of biopolymers in the construction of the mineral and
carbohydrate skeletons that constitute most fossils. The third is the historical information that may
be obtained in a quantitative form from comparisons of the primary structures of the proteins and
genomes of living organisms. I deal briefly with each of these aspects below. As you will see, there are
at present more questions than answers. The great potential of molecular palaeontology has yet to be
realized, and in that sense, molecular palaeontology may be compared with isotopic dating and
palaeomagnetism at the end of the 1940s.

The literature of molecular biology is overwhelming ( Biochimica et Biophysica Acta ran to 46
volumes in 1981 and about 10 new journals in the field appeared in the twelve months to March 1985).
Consequently, suitable examples may be selected more-or-less at random. I have therefore chosen—
so far as is possible— to use examples based upon work done in Australia or upon Australian
materials. This fact alone will demonstrate that the treatment is far from comprehensive.

Before proceeding, however, it should be pointed out that the sister discipline of molecular
palaeontology is ‘atomic palaeontology’. Atomic palaeontology deals (for example) with informa-
tion obtained from stable isotopes, with the distribution of major and trace elements in skeletal
materials, and, of course, with the presence of anomalous amounts of iridium and other noble metals.
The potential of these kinds of data to palaeontology may be illustrated by the following simple
example.

The ratio of deuterium (D) to hydrogen in the cellulose of woody tissues is thought to diminish in
plants living at progressively higher latitudes (Smith el al. 1983). Although the causes of this
relationship are not well understood (Lawrence and White 1984), Smith et al. have been able to show
a correlation between the D/H ratios of Australian and Antarctic coals and the palaeolatitudes of
their formation. It may therefore be possible to use this technique to determine palaeolatitudes in
areas such as Indonesia where the tectonic history and palaeobiogeography are still not well
understood (Audley-Charles 1983; Runnegar 1984«).

BACKGROUND

The fundamental difference between most biological and geological materials is explained simply at
the molecular level. In geological systems nearly every atom is linked covalently to other atoms in all
directions; in biological systems the covalent bonds are found only along the backbones of linear
polymers and the other bonds are weak (Frauenfelder 1983). This immediately explains the softness
and flexibility of most biological materials and its highlights the importance of linear polymers to the
origin and evolution of life.

A second important point is that biological materials tend to be less ordered than inorganic
crystals. According to Galloway (1984), topology is more important than geometry and a biological
structure requires no more order than is necessary for it to work. Thus biological materials exhibit
some of the properties of crystals and others of liquids. Crystalline order may be present in only one
dimension — the one that is required for the structure to function.

A third important point is that linear polymers contain information of the kind not normally
expected in three-dimensional crystal lattices (Dose 1983; Matsuno 1983). The sequence of the
subunits (residues) provides historical as well as functional information even in molecules such as
collagen in which the nature of particular subunits is relatively unimportant. Thus it is the collection
and preservation of information that distinguishes life from inanimate objects, and it is this
information that is beginning to tell us so much about the way evolution has occurred.

The four main types of linear polymers found in biological systems are nucleic acids (DNA and
RNA), proteins, lipids, and carbohydrates. Sugars are particularly unstable under geological
conditions so carbohydrates and nucleic acids (in which the bases are linked by sugar rings) are
unlikely to survive fossilization (Calvin 1968). Some proteins and many lipids are far more stable and
may be isolated (usually in a modified form) from ancient rocks.

RUNNEGAR: MOLECULAR PALAEONTOLOGY

3

FOSSIL MOLECULES

In addition to the long list of ‘prebiotic’ organic molecules that have been discovered recently in
interstellar space and carbonaceous chondrites (Brown 1980), a large number of different kinds of
organic molecules have now been extracted from terrestrial rocks, principally as a result of the
development of computerized gas chromatography-mass spectrometry (Ourisson et al. 1979, 1982,
1984; Mackenzie et al. 1982). This field is of great importance to the petroleum industry (Brooks
1981) and is far too large for this brief review; I shall therefore mention only some of the interesting
results of recent studies to illustrate both the potential and the limits of the data.

About 50 years ago, A. Treibs suggested that a common vanadium petroporphyrin (vanadyl
deoxyphylloerythroetioporphyrin, DPEP) is the normal geological product of the magnesium-
porphyrin complex of the chlorophyll a found in all oxygen-producing photosynthetic cells. The
vanadyl derivative had been synthesized several times but its identity with the natural product was
not confirmed until 1983 when Ekstrom et al. (1983) determined the crystal structure of vanadyl
DPEP from an Early Cretaceous oil shale (Toolebuc Formation; Saxby 1983) in western Queensland.
Similarly, the structure of a nickel petroporphyrin (abelsonite) from the Eocene Green River
Formation of Utah was first determined last year (Storm et al. 1984); it also appears to be a
chlorophyll derivative but the structure alone does not pinpoint derivation from chlorophyll a.

Chlorophyll molecules — which consist of the magnesium-porphyrin complex and a long phytol
side chain— are supported within protein baskets in the photosynthetic membranes (Thornber and
Markwell 1981). The structure of a bacteriochlorophyll a-protein association has been determined
by X-ray crystallography to a resolution of 0-28 nm (Matthews et al. 1979), and a comparison of
this structure with DPEP shows how much has been lost during fossilization. Although the
demonstration that a 100-million-year-old vanadyl porphyrin is derived from chlorophyll a
respresents a significant achievement in molecular palaeontology (Ekstrom et al. 1983), it is clear that
only the most stable kinds of biological molecules are likely to be extractable from rocks and that
determination of their structure will be a protracted process.

Like the monoplacophoran Neopilina and the coelacanth Latimeria, there is an important class of
fossil molecules that was extracted from rocks before being discovered in the living biota (Ourisson
et al. 1979, 1982, 1984). These molecules, now known to be derivatives of components of bacterial
membranes, are called hopanoids. They indicate that a significant fraction of all crude oils is of
bacterial origin. Hopanoids are also abundant in low-rank coals; for example, Ourisson et al. ( 1 984)
estimated that each cubic metre of an Australian Palaeocene lignite contains about one kilogram of a
particular hopanoid acid. Other unusual hopanoids are found in both the Victorian lignites and
crude oils from the nearby offshore Gippsland Basin (Philp and Gilbert 1982). These kinds of
observations are being used to study the history of the generation and migration of the economically
and strategically important Gippsland Basin oils.

All cells are surrounded by membranes (not to be confused with cell walls) that act as dynamic
barriers between the external environment and the cytoplasm (Lodish and Rothman 1979). Cell
membranes are composed of three main components, lipids, proteins, and carbohydrates. The lipids
and proteins are the major components and are present in approximately equal masses, but the
protein molecules are much larger than the lipid molecules so lipids are far more numerous.

Lipids are elongate amphipathic structures. This means that they have a hydrophobic end (soluble
in oil) and a hydrophilic end (soluble in water). The hydrophobic ends point towards the centre of the
lipid bilayer that forms the membrane and the hydrophilic heads face outwards on either side. In
mammalian cells there are two main kinds of lipids— flexible molecules (phospholipids) and rigid
ones (cholesterol). The rigid cholesterol molecules act as struts to strengthen the membrane whereas
the phospholipids allow the membrane to be flexible and, in places, to have a small radius of
curvature.

The hopanoids are now believed to be the bacterial analogues of cholesterol (Ourisson et al. 1982,
1 984). They also have pronounced amphipathic properties and are similar in shape to cholesterol, but
the hydrophilic parts of the two molecules are at opposite ends. A large number of derivatives of

4

PALAEONTOLOGY, VOLUME 29

bacterial hopanoids have been recovered from sedimentary rocks in the last few years (Ourisson et al.
1979; Mackenzie et al. 1982).

The point to be made here is that molecular palaeontology has yielded new insights into the nature
of bacterial membranes as well as providing an important tool for studies of oil genesis (Mackenzie
et al. 1982). Because hopanoids are only soluble in mixtures of polar and non-polar solvents (say
chloroform and methanol) they were not discovered in living bacteria until a deliberate search for
them was made (Ourisson et al. 1984).

Palaeobio chemistry

The analysis of molecules obtained from fossils has generally been described as ‘palaeobiochemistry’
to distinguish such studies from those dealing with molecules dispersed in sedimentary rocks.
Palaeobiochemistry also has considerable potential despite somewhat inauspicious beginnings.

Although there have been some partly successful attempts to characterize lipids and nucleic acids
from extinct organisms (Niklas et al. 1982; Higuchi and Wilson 1984; Higuchi et al. 1984), most work
in palaeobiochemistry has concentrated on fossil proteins (Abelson 1956; Degens 1967; Armstrong
et at. 1983). The preservation of objects resembling cell nuclei in silicified cycad wood from the
Triassic of New Mexico (Gould 1971) could indicate that some components of nucleic acids may
survive in exceptional circumstances, but it is unlikely that much information will be recovered from
fossil nucleic acids even if they are found in ancient rocks. On the other hand, even though lipids are
more stable than proteins, they contain too little information to be of any real significance except in
the ways already explained. Thus fossil proteins offer the best hope for palaeobiochemical work.
A variety of techniques have been explored; they include solid-phase radioimmunoassay of collagen
from living and extinct vertebrates (Lowenstein 1980)— the technique used to show that the
Piltdown jaw came from an orangutan (Lowenstein et al. 1982), measurements of the extent of
racemization of amino acids in skeletal proteins (Kimber and Milnes 1984), and determinations of
the concentration of y-carboxyglutamic acid (Gla) in modern and near-modern bones (King 1978).
Each method has its own particular problems and all work best with modern and subfossil materials.
Such techniques are therefore likely to be of most use to Quaternary geologists and biologists.

MOLECULAR FOSSILS

Proteins are linear polymers of amino acids linked by peptide bonds. The ‘central dogma’ of
molecular biology is that the information content of nucleic acids is translated into the amino-acid
sequences— the primary structures— of the proteins they specify (Ayala 1978). DNA is transcribed
into messenger RNA (mRNA) by enzymes called RNA polymerases and translation of the mature
mRNA occurs by an interaction of transfer RNAs (tRNAs) with both the mRNA and disjunct amino
acids in ribosomes. In higher organisms (eukaryotes) the genes normally consist of separate coding
regions (exons) and non-coding regions (introns). The introns are removed during RNA processing
and the ends of the exons are spliced together to make the mature mRNA (Mattaj 1984).

The information potential of nucleic acids and proteins is prodigious. Bodemniiller and Schaller
(1981) have demonstrated that an identical 1 1-amino-acid (head activator) neuropeptide occurs in
animals as distant as cnidarians and humans. Although the part of the gene coding this particular
neuropeptide has not yet been sequenced, the nature of most of its DNA sequence may be inferred
from the genetic code:

GA^CC-CC-GG-GG-TC-AA^GT AT-Jt TtJ

(A, adenine; G, guanine; C, cytosine; T, thymine; sites indicated by dashes could be any one of the four
nucleotides). A DNA sequence of this form represents one of about 1014 possibilities, so even though
the neuropeptide is a very small molecule the probability of it having arisen twice by chance is
vanishingly small (there are about 4 x 1013 micrometres in the circumference of the Earth). Thus we
can be reasonably certain that this short segment of DNA has been passed from generation to

RUNNEGAR: MOLECULAR PALAEONTOLOGY

5

generation in an almost unaltered form since the time of the last common ancestor of cnidarians and
vertebrates some 800 million years ago. As such, it represents an extraordinary 'molecular fossil’.

If all polypeptides had changed as little as the head activator neuropeptide in the course of
evolution the diversity of life would be low and there would be not much to be learned from a
comparison of similar (homologous) proteins of different organisms. However, as the rates of
evolution of different kinds of proteins (and their coding sequences) have varied considerably, the
comparative biochemistry of homologous proteins is a vast potential source of historical
information.

Broadly speaking, proteins may be lumped into three main groups. Many are roughly globular to
equidimensional in shape and being water-soluble (hydrophilic) move freely in the cytoplasm. Others
are hydrophobic and lie within the lipid bilayers of the cell membranes, and still others are fibrous and
serve structural roles (e.g. in muscles and connective tissues). Until recently, most of the published
amino-acid sequences were those of the hydrophilic equidimensional proteins because these are more
easily extracted and studied. The fibrous proteins tend to have highly repetitive amino-acid sequences
that are tedious to determine by traditional methods and the hydrophobic membrane proteins are
hard to extract. However, the development of rapid and efficient methods of gene sequencing in the
last few years has made available the nucleotide sequences of the genes for a great variety of different
kinds of proteins. These nucleotide sequences may be converted into amino-acid sequences using the
genetic code.

Just as there are three main groups of proteins, so there are three main kinds of protein structures:
a-helix, /3-pleated sheet, and a triple helix typified by the structure of the protein collagen (Richardson
1981; Walton 1981). Many proteins are formed of domains of a and /3 structures but others — such as
the globins — are dominantly of one type.

The comparative biochemistry of homologous proteins has yielded a large amount of phylogenetic
information in the past two decades. Generally speaking, the degree of smilarity between
homologous proteins of two or more kinds of organisms may be expressed in either qualitative or
quantitative terms, but it is the possibility of quantification that has excited the imagination of those
interested in the evolution of life. This can be done in a number of ways (for example, by measuring
electrophoretic differences), but the most appealing method is a direct comparison of the amount of
similarity in the amino-acid sequences of homologous proteins (or nucleic acids). This has led to the
development of many different kinds of 'molecular clocks’ since the idea was first suggested in 1 962 by
Pauling and Zuckerkandl (1962; see Wilson et al. (1977) for a review). The method has great promise
for studies of recent evolutionary events (e.g. the evolution of man; Lowenstein and Zihlman 1984),
but from a palaeontologist’s point of view an exciting aspect is the potential to look beyond the good
fossil record into the vast unknown of the Precambrian. I propose to illustrate this point by discussing
briefly some of the molecular and other evidence for the Precambrian history of the Metazoa.

There are three fundamental aspects of the early history of the Metazoa that remain enigmatic.
First, are metazoans a monophyletic group descended from a single common multicellular ancestor?
Second, are metazoans descended from ciliated protists like Paramecium , from other kinds of
protists, or indeed, from non-protistan eukaryotes? And third, when did the Metazoa first evolve?
Answers to these questions may now be becoming available through the data of molecular biology.
For example, the question of the monophyletic versus polyphyletic origin of the Metazoa (Anderson
1982) would seem to be settled by the following evidence.

Metazoans are monophyletic

Collagen is the principal structural protein of metazoan connective tissue and the most abundant
protein in higher vertebrates. It has been found in representatives of every metazoan phylum studied
and appears to be restricted to the Metazoa (Adams 1978; Towe 1981 ) although an enzyme required
for the post-translational hydroxylation of proline residues seems to have been inherited from the
common ancestors of animals and plants (Ashford and Neuberger 1980). Consequently, if the
collagens of distantly related metazoan phyla could be shown to be homologous, this would provide
powerful support for the idea that all metazoans share a common multicellular ancestor.

6

PALAEONTOLOGY, VOLUME 29

There are at least nine different types of vertebrate collagens but the ones of importance for this
discussion are those known as the fibrillar collagens (Types I to III). They occur in a variety of tissues
including skin, liver, bone, and cartilage (Bornstein and Sage 1980).

Fibrillar collagens are composed of long triple helices formed of identical or homologous
polypeptides having the repetitive amino-acid sequence (G-X-Y)w, where G is glycine and X and Y
are usually proline, alanine, or a charged residue. A post-translational conversion of many of the
proline residues to hydroxyproline is required to stabilize the secondary and tertiary structures of the
molecules, and it is significant in another context that this post-translational modification requires
molecular oxygen (Towe 1970, 1981).

The collagen triple helices, and their short terminal non-helical segments, are overlapped to form
fibrils by a distance «D, where D = 234 amino acid residues (Woodhead-Galloway 1980).
Hydrophobic and electrostatic interactions between adjacent triple helices are maximized when the
molecules are staggered in this way, and the tensile strength of the whole fibril is provided by the
development of covalent bonds between adjacent triple helices.

When collagen fibrils are positively stained with heavy metals for electron microscopy the stain
accumulates at the sites of the charged residues and a distinctive banding pattern results (Woodhead-
Galloway 1980). Because fibrils are composed of triple helices overlapped by 234 residues the
banding pattern has a repeat distance (67 nm) that is equal to the average distance between adjacent
residues (0-286 nm) multiplied by 234. However, if the molecules are separated from each other and
then recombined so that they lie in register side by side, positive staining of the (SLS) aggregate
reveals a banding pattern which is essentially a map of the distribution of charged residues in the
molecules (text-fig. 1).

Because the amino-acid sequences of several different kinds of vertebrate fibrillar collagens have
been determined either by conventional methods or by gene sequencing (Runnegar, in press a),
computer-drawn plots of the charged residues may be used to simulate the patterns observed in the
SLS aggregates (text-fig. 1). It is, therefore, possible to make a direct visual comparison between the
amino-acid sequences of different collagens using either photographs of positively stained SLS
aggregates or computer-drawn maps of the amino-acid sequences.

It has been known for some time that the SLS banding patterns of fibrillar collagens from the
mesogloea of the cnidarian Actinia equina , the body wall of the parasitic platyhelminth Fasicola
hepatic a , and various vertebrates are almost identical (Nordwig and Hayduk 1969). It has recently
been shown that collagen from the byssus of the mollusc Mytilus edidis has an SLS banding pattern
like that of vertebrate Type I collagen (DeVore et al. 1984). These similarities are obvious in text-
fig. 1. Furthermore, the invertebrate collagens are more similar to vertebrate Type I collagens than
they are to vertebrate Type III collagens. Thus there is a greater similarity in the collagens of distant
phyla of the Metazoa than there is between collagen molecules that may be covalently cross-linked in
a single tissue (Henkel and Glanville 1982).

Because the function of collagen molecules is to resist tension, they are designed and act like ropes.
The repetitive nature of their amino-acid sequences results from fact that glycine is the only residue

text-fig. 1. Distribution of charged residues in the telopeptides of homologous vertebrate and invertebrate
collagens. The top and bottom bars are computer-drawn representations of the rat -(-calf a(l)I and calf skin
a 1 (III) sequences (references in Runnegar, in press a) and the other bars are enlarged copies of published electron
micrographs of positively stained SLS aggregates, as follows: V, vertebrate Type 1 collagen (after Bentz et at.
1978, fig. 3, republished with permission); P, C, platyhelminth body-wall collagen and cnidarian mesogloea
collagen (both after Nordwig and Hayduk 1969, pi. 7, republished with permission); M, mollusc byssus collagen
(traced from photographic enlargement of fig. 3 A of DeVore et al. 1 984); the vertebrate collagen is repeated for
clarity. Arrows at top point to clusters of charged residues that are conserved in all molecules; the arrows at the
bottom point to clusters of charged residues that are present in vertebrate Type I collagens and the invertebrate
collagens but not in vertebrate Type III collagens.

aid)

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8

PALAEONTOLOGY, VOLUME 29

small enough to fit into the axis of the triple helix. Apart from this constraint and the need for certain
proportions of hydroxyproline and charged residues, there would appear to be no particular
reason— other than a historical one— for the charged residues to be distributed in the way that
they are. Collagen genes appear to have been constructed by the serial repetition of an original
54-nucleotide module (Yamada et al. 1980; Runnegar, in press a ), so the disorder evident in the
distribution of charged residues represents a unique subsequent development. It is therefore clear
that living vertebrates, cnidarians, platyhelminths, and molluscs have inherited homologous collagen
genes, presumably from a remote common metazoan ancestor. This is excellent evidence that the
metazoans represent a monophyletic clade.

There is, however, one possible flaw in this logic. There is now ample evidence that copies of DN A
sequences may be transferred from one genome to another. Such transfers are common within the
cells of single organisms; for example, an ATPase gene has migrated from the mitochondria to
the nucleus of bakers yeast, the mitochondrial and nuclear genomes of rat liver cells have a
common sequence about 3000 nucleotides (nt) in length, and there are extensive homologies
between the mitochondrial and chloroplast DNAs in some higher plants (Hadler et al. 1983;
Stern and Palmer 1984). Gene transfer may also occur between organisms by means of viruses or
bacterial plasmids.

It is, therefore, at least conceivable that the present distribution of fibrillar collagen genes is due in
part to lateral gene transfer. This explanation is improbable for two reasons. First, collagen is a vital
material for all metazoans so any lateral gene transfer would have had to have coincided with the
development of multicellularity; this scenario therefore requires the improbable synchronous
occurrence of two events. And second, fibrillar collagen genes are large and complex. For example,
the chicken a(2)I gene contains 49 exons and non-coding regions that are about 3-4 x 103 nt in total
length (Tate et al. 1983). It seems unlikely that such a complex gene could be transferred intact to
another genome. When the problems of gene expression after transfer are considered as well, the
possibility of lateral transfer of collagen genes becomes remote. This may not be true for smaller and
simpler genes.

Graptolite collagen genes

All of the collagens discussed so far were obtained from living animals. But can anything be learned
about the collagens of long-extinct organisms? Surprisingly, the answer appears to be yes, because it
is becoming apparent that properties of genes are reflected in structures that may be observed in well-
preserved fossils.

In collagen genes, most of the exons that encode the triple helical part of the protein molecule are
small integral multiples of 54 nt in length (Tate et al. 1983). The others are either 45 (54 — 9) or 99
(54 x 2 — 9) nt in size and are believed to have been shortened from an original length of 54 n nt by the
removal of a segment coding for one G-X-Y amino-acid triplet. This explains why collagen genes are
thought to have evolved by the tandem repetition of 54-nt modules (Yamada et al. 1 980; Runnegar, in
press a).

Only part of a single Drosophila collagen gene has so far been sequenced (Monson et al. 1 982), but
at least one of the two exons present in the fragment appears to have been 702 (54 x 13) nt in length
prior to the deletion of a few nucleotides (Runnegar, in press a). When this fact is coupled with
repetitions discovered by McLachlan (1976) in the amino-acid sequence of a vertebrate Type I
collagen, it seems likely that collagen genes were also constructed by the successive duplication of
702-nt secondary modules (McLachlan 1976; Runnegar, in press a). This explains the origin of the
D-period in collagen fibrils (702 nt = 234 amino acids).

Because the collagen triple helices are not integral multiples of 234 amino acids in length, there are
spaces (holes) between the ends of the triple helices (Woodhead-Galloway 1980). These holes become
filled with heavy metal stains with the fibrils are negatively stained for electron microscopy, and they
become filled with apatite when collagen is mineralized (Berthet-Colominas et al. 1979). Thus
negatively stained collagen fibrils exhibit an alternation of light and dark crossbands under the
electron microscope and the dark bands correspond to the positions of ‘hole zones’ (Woodhead-

RUNNEGAR: MOLECULAR PALAEONTOLOGY

9

Galloway 1980). As a result of the geometry of packing, each pair of light and dark bands is 67 nm
(234 amino acids) in length.

Freeze-fracture replicas of unstained collagen fibrils display similar crossbands bacause the
‘hole zones’ are less voluminous than the intervening regions (Leonardi et al. 1983). Thus
the fundamental construction of collagen genes may be determined from measurements of
the morphology of essentially untreated collagen fibrils. It is merely necessary to know the
inter-residue spacing of a synthetic polymer of the collagen type (0-285 nm in poly L-prolyl-
glycyl-L-proline; Traub and Yonath 1966) and the period of the cross band (67 nm) to determine—
with the advantage of hindsight — that collagen genes are constructed from 702 and/or 54-nt
modules (67 nm/0-285 nm = 235 x 3 ~702 = 54 x 13; a more precise value for the inter-residue
distance in unstretched tendon collagen (0-2866 nm; Fraser et al. 1979) gives a better result: 233-8
residues, 701-3 nt).

Flow does all this relate to palaeontology? It turns out that the same kinds of deductions can be
made from molecular structures observed in the graptolite periderm. Towe and Urbanek (1972),
Urbanek and Towe (1974, 1975), and Crowther and Rickards ( 1977) have illustrated banded fibrils in
the cortical layers of Late Ordovician specimens of Dictyonema. These fibrils have been interpreted as
the remains of original collagen, both on the basis of their morphology (Towe and Urbanek 1972)
and on the spacing of distinctive crossbands (Crowther and Rickards 1977). More recently,
Armstrong et al. (1984) have shown that the extra-cellular tubes of living pterobranchs are
collagenous in composition, thus supporting the earlier interpretations of the structures found in
graptolite skeletons and also the hypothesis that the graptolites are closely related to the
pterobranchs.

Crowther and Rickards were not particularly interested in the exact value of the periodicity in the
crossbands of the fibrils of Dictyonema since a value of about 70 nm was sufficient to establish the
collagenous nature of the material. Flowever, measurements made from their published photographs
suggest that the repeat distance lies between 65 and 70 nm. It is, therefore, likely that the triple helical
molecules of the cortical collagen of Dictyonema were staggered by 67 nm and that Dictyonema
collagen genes were constructed from 54 nt modules. Thus graptolite collagen appears to have been
homologous to the collagens illustrated in text-fig. 1 .

The crossbands of graptolite collagens are visible in ultra thin sections and therefore cannot be
merely a topographical feature (Towe and Urbanek 1972, fig. 4). The alternation of light and dark
bands is reminiscent of the pattern seen in negatively stained fibrils and so it is possible that the
electron-dense regions represent hole zones that have been partially mineralized during preservation
and diagenesis. If introduction of mineral into these regions has mimicked the effects of negative
staining and biomineralization, it may be possible to find traces of collagens in other invertebrate
fossils and hence to use the crossbanding patterns to learn something about the nature of their
collagen genes.

Dating the origin of the Metazoa

Differences in the sequences of homologous proteins and nucleic acids from different animal phyla
may — at least in theory — be used to date the times of origin of the various animal phyla. However,
the amount of useful information so far available is limited and the only question worth addressing at
present is whether the animal phyla have a short or long Precambrian history (Sepkoski 1978;
Runnegar 1982a).

The method involves a quantitative comparison of the residues of homologous biopolymers
(usually given as percent difference); a correction for substitutions that have reverted to the original
condition and thus appear unchanged whereas they have changed twice, and a calibration of the
rate of evolution based upon an event that can be identified (and isotopically dated) in the fossil
record. Thus, the method is not simple and it involves a number of factors that are difficult to
determine.

There is an additional complication in that it is necessary to deal with two kinds of divergence— the
divergence of lineages and the divergence of genes. Duplicate copies of genes within organisms begin

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PALAEONTOLOGY, VOLUME 29

to evolve separately once duplication has occurred. Some copies become so modified as to be
unserviceable and may remain in the genome as non-functional pseudogenes. For example, the
human genome contains two closely related embryonic a-like globin genes, only one of which encodes
a functional polypeptide (Proudfoot et al. 1 982). The protein-coding regions of the two genes differ in
only three nucleotides but one of these mutations has produced a termination codon in the non-
functional gene. The protein-coding sequence can therefore not be translated into a globin molecule
and it resides in the genome as an unexpressed pseudogene.

It is clear from this simple example that genes have their own histories of origin, evolution, and
extinction. Perhaps all modern genes are copies that have been re-copied many times, not only from
generation to generation, but from place to place within evolving genomes. The extra copies appear
to serve three main functions: they enable their products to be manufactured quickly; they represent a
safeguard against failure through mutation; and they provide scope for experimentation (one copy
can evolve while another continues to manufacture a vital product). The possibility that unexpressed
pseudogenes may return to a functional role after a period of evolution remains little more than an
idea but it exemplifies the way molecular biology is changing the way we look at evolutionary
mechanisms.

As well as giving an indication of the age of the Metazoa, the respiratory pigments known as
globins illustrate the basic principles of molecular evolution. At present, globins are probably the best
examples available because they can be shown to be homologous, they have evolved at an
intermediate rate, and a large number of complete amino-acid sequences are available.

The protein part of a globin molecule resembles a framework constructed from unequal lengths
of pipe joined by U-pieces. The pipe-like parts are lengths of a-helix, and, as most of the molecule has
this kind of structure, there are limited constraints on the nature of many of the 140 or so amino-acid
residues. The ‘works' of a globin— the part that reversibly binds oxygen — is an iron-porphyrin
complex not very different from the magnesium-porphyrin complex of the chlorophylls. It lies within
the protein frame and is held in place by the side chains of greatly conserved amino-acid residues
(Dickerson and Geis 1983).

Because the segments of a-helix are unequal in length the tertiary structure of globin molecules is
quite irregular. The same irregular structure is present in globins from vertebrates, an annelid, an
insect, and the root nodules of a legume (Lesk and Chothia 1980). When these features are coupled
with the common characters found in globin genes and their amino-acid sequences, there can be little
doubt that all globins are homologous (Runnegar 1984 b).

Globin molecules found in muscle cells (myoglobins, Mb) are monomeric, but the globins
that circulate in body fluids (haemoglobins, Hb) are generally either intracellular small
polymers (commonly four subunits) or large extracellular polymers of as many as 186 subunits
(Messerschmidt et al. 1983). In all living vertebrates except jawless fish the main component
of haemoglobin is a tetramer formed of two pairs of distantly related globin monomer called
the a and f3 chains.

The primordial a and jS haemoglobin genes were produced by a gene duplication that post-dated
the evolution of the jawless fish during or prior to the late Cambrian. The duplication occurred in the
lineage leading to all other vertebrates, including sharks. It is, therefore, possible to date this gene
duplication event to about 450 million years ago (middle-late Ordovician) and to use this date to
calibrate the rate of evolution of globin molecules.

Once the gene duplication had occurred and a and j8 genes began to evolve independently. Each
living organism possessing these genes has had the same amount of time for evolution to occur, so the
amount of difference between the amino-acid sequences of any a and j8 haemoglobin should be
exactly the same if the molecular clock has any meaing. Any depatures from equivalent amounts of
difference may then be attributed to variations in the rate of change, or perhaps, to a greater tendency
to revert to the original condition.

As might be expected, a comparison of a large number of a and (8 haemoglobin sequences reveals
that some pairs are more alike than others. However, a histogram of the frequency of the values
obtained from pairwise sequence comparisons displays all of the characteristics of a normal

RUNNEGAR: MOLECULAR PALAEONTOLOGY

1 1

a/0 haemoglobin differences. ASS comparisons.

text-fig. 2. Histogram of the observed percentage differences obtained from the pairwise comparison of the
amino-acid sequences of vertebrate a and /3 haemoglobins (N = 2915, x = 61-6, S = 3-2). The distribution is
statistically insignificantly different from normal except for a small amount of skewness.

distribution except for a small but statistically significant amount of skewness (text-fig. 2). This
distribution illustrates the point that molecular clocks are ‘sloppy’ and that results obtained from
comparisons of only a few sequences are likely to be misleading. On the other hand, the average
difference obtained from the 2915 sequence comparisons used for text-fig. 2 is 61 -6%; this value is not
very different from a mean value of 61-05% obtained previously from only eighty sequence
comparisons (Runnegar 1982a).

The problems of correcting for superimposed mutations (ones that have resulted in the restoration
of the original condition), and for the fact that certain amino acids are more likely to be replaceable
than others, is beyond the scope of this brief review (see Golding 1983 for a recent discussion). There
is, however, a need for some kind of correction for superimposed mutations and the simple method
described in Runnegar (1982a) will be used here.

It is, of course, often claimed that the rates of evolution of different proteins have varied at different
periods of time. For example, the rates of evolution of higher primate globins are thought to have
been exceptionally slow because a molecular clock date for the origin of man is much too young. On
the other hand, some authors have suggested that proteins evolve quickly when they first appear and
that the rate of evolution slows down subsequently. Other argue for alternations of fast and slow
rates (Goodman 1981).

It seems possible that rates of evolution obtained from proteins and nucleic acids may be unreliable
when based upon small samples or closely related molecules. With larger samples and/or longer

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PALAEONTOLOGY, VOLUME 29

B Hb

B Hb

OBSERVED

B Hb

COMPARISON

text-fig. 3. Comparison of the observed and expected differences between the amino-acid sequences of shark
and human a and j8 haemoglobins. See text for further explanation. The relatively small difference between the
a and /3 haemoglobins of humans is unusual (text-figs. 2 and 4).

periods of time, the molecular clock seems to work, at least in an approximate fashion. For example,
the potential of the globin clock may be illustrated in the following simple way:

1 . The last common ancestor of humans and modern sharks was a Late Ordovician or Silurian fish
that had inherited the recently acquired duplicate genes for the a and /3 chains. Therefore, the a and
globins of the shark have been isolated from their human counterparts for almost as long as the
duplicate genes have been evolving independently. Consequently, it is not surprising that there is
almost the same amount of difference between the a globins of sharks and humans as there is
between their j3 globins, and that both figures are close to the average difference (61%) between the a
and /3 globins of living vertebrates (text-fig. 2). It is, therefore, possible to model the expected results
and to compare observed with expected values (text-fig. 3). The close fit supports the idea that shark
globins have evolved at much the same rate as those in the vertebrate lineage leading to man, despite
the fact that the physiological requirements of sharks and mammals are quite different.

2. The evolution of the a and /3 globins may be illustrated diagrammatically in clock form (text-
fig. 4). The diameter of the face of the clock may be used to represent the average percentage sequence
difference between the a and /3 globins of living vertebrates and the length of the hands can represent
the observed percentage sequence difference in each particular case. If hands representing the human
a and (8 globins are placed at 12 and 6 o’clock, and the comparative sequence differences in other
globins are shown as the clockwise distance away from the human position, three things are obvious.
First, the sequence difference between a and jS globins is similar in all six animals; second, both kinds
of globin depart by a roughly equal amount from their human counterparts; and third, the amount of
sequence difference corresponds well with the evolutionary distance from humans.

3. An earlier duplication of a vertebrate myoglobin gene led to the evolution of the vertebrate
haemoglobins from one of the duplicates (Dickerson and Geis 1983). It is, therefore, to be expected
that the average sequence difference between a globins and vertebrate myoglobins will be equal to the
average difference between /3 globins and the myoglobins. This turns out to be the case; the values are
74-1% and 72-9% respectively when compared over the same number of residues (text-fig. 5).

There are now a number of invertebrate globin sequences available (Runnegar 19846). Three-way
comparisons of annelid, mollusc, and vertebrate sequences show that between-phylum differences
(about 80%) are greater than those found within the vertebrates (text-fig. 5).

The results shown in text-fig. 5 are based upon more than a million amino-acid residue
comparisons. If the mean values obtained from each set of comparisons are corrected for
superimposed substitutions it is possible to use the corrected values to estimate the date of the gene
duplication that produced the ancestral vertebrate haemoglobin gene from a pre-existing myoglobin

RUNNEGAR: MOLECULAR PALAEONTOLOGY

13

HUMAN MOUSE RABBIT

text-fig. 4. Molecular evolution of selected vertebrate a and /3 haemoglobins shown in clock form. See text for
further explanation. From Runnegar (1982c, fig. 5), republished with permission.

gene, and also to derive an approximate minimum date for the initial radiation of the animal phyla
(text-fig. 6). The logic is as follows.

The rate of evolution of the globins is calibrated by the gene duplication that produced the
ancestral a and /3 chains in the Ordovician as described above and in Runnegar (1982n). As the
vertebrates are monophyletic and did not originate until the late Cambrian (Briggs and Fortey 1982),
their early Cambrian and Precambrian history comprises a single species-lineage. The divergence-
times obtained from a-Mb and /3- Mb comparisons therefore date this event within that lineage. In
other words, ‘vertebrate’ haemoglobin first appeared in a direct ancestor of the Vertebrata during the
Ediacarian (text-fig. 6). This ties in fairly well with the idea that respiratory transport pigments— as
distinct from muscle storage pigments— evolved during the Ediacarian in response to increasing
amounts of free oxygen in the atmosphere and hydrosphere (Runnegar 19826, c).

A parallel development probably took place within the lineages leading to other animals phyla
(e.g. the Mollusca), but there is at present too little information for a similar analysis of invertebrate
globins. However, if all globins are monophyletic, between-phylum comparisons may be used to
obtain an approximate minimum date for the initial radiation of the animal phyla. The value of about
800 million years ago shown in text-fig. 6 is likely to be an underestimate for two reasons: first, only
homologous residues were used for the sequence comparisons and all unmatched segments of the
molecules were excluded; and second, there is an upper limit to change which may be being
approached in such different amino-acid sequences. Thus the limited evidence available from the
globin clock points to a Precambrian history of the Metazoa of the order of 200-400 million years
(text-fig. 6; Runnegar 1982n; see Gingerich (1984) for a different interpretation).

PALAEONTOLOGY, VOLUME 29

text-fig. 5. Histograms of the observed percentage differences obtained from the pairwise comparison
of the amino-acid sequences of vertebrate and invertebrate globins (plotted at different vertical scales).
A-M, annelid/mollusc, A = 21, Jc = 8 1 -2, 5 = 2-8; M-V, mollusc/vertebrate, N = 987, 5 = 78-2, 5 = 2-9;
A-V, annelid/vertebrate, N = 423, 5 = 80-4, 5 = 3-6; /J-Mb, vertebrate (3 haemoglobin/vertebrate myoglobin,
A=1749, 5 = 72-9, 5 = 2-0; a-Mb, vertebrate a haemoglobin/vertebrate myoglobin A=1815, 5 = 74-1,
5 = 2-0; a-fi, vertebrate a haemoglobin/vertebrate /3 haemoglobin as in text-fig. 2.

text-fig. 6. A, molecular estimates of the time of origin of the metazoan phyla based upon the data given in
text-fig. 5 (globins) and on differences in the amino-acid sequences of cytochrome c and the nucleic-acid
sequences of 5S rRNAs. The rates of evolution are based upon dated events within the Phanerozoic such as the
origin of the genes for a and [3 haemoglobins, the origin of the echmoderm classes (E) and times of divergence of
various vertebrate groups (fish/mammals, birds/mammals, etc.). Because 5S rRNA molecules have evolved
slowly it is difficult to calibrate their rate of evolution from the information currently available. A distant
calibration point may be provided by the average difference between fungal and animal 5S sequences (F-A), on
the assumption that these two kingdoms last shared a common ancestor about 1300 million years ago
(a somewhat younger date is given by the cytochrome c data). A slower rate of 5S rRNA evolution is indicated
by comparisons between molluscan and echinoderm classes (M, E). The solid field indicates the limits of points
derived from between-phylum comparisons; the spots above this field were obtained from between-phylum
comparisons of cytochrome c sequences, b, observed decline in abundance/diversity of late Proterozoic and
Cambrian stromatolites (Walter and Heys, in press), probable minimum time of origin of vertebrate collagen
genes (Runnegar, in press a ), and a backwards extrapolation of Sepkoski’s (1978) estimate of the number of
metazoan orders in the Ediacarian and Cambrian. The extrapolation is based upon the premiss that between 1
and 10% of metazoan orders existing at the time were fossilized.

DIVERGENCE

AGE

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PALAEONTOLOGY, VOLUME 29

The globin data are supported in a limited way by data from amino-acid sequences of the protein
cytochrome c and the nucleotide sequences of small ribosomal RNA molecules (5S rRNAs; text-
fig. 6). In the case of the 5S rRNA sequences, the rate of evolution may be calibrated in two ways,
either by using limited data from different classes of molluscs and echinodenns (M, E, text-fig. 6)
or by using data from fungi which appear to have diverged from the lineage leading to the animals
some 1200-1300 million years ago. Because of the very limited number of sequences available the
estimates of the times of divergence of the animal phyla shown in text-fig. 6 should not be taken
too seriously; they are presented here more to illustrate the technique than to provide an answer
to the problem.

Another way of looking at this problem is to assume that the Ediacarian and Cambrian fossil
record is likely to contain between one and 10% of the higher taxa that existed at the time. If so,
it may be possible to extrapolate Sepkoski’s (1978) curve of the diversity of Ediacarian-Cambrian
marine orders backwards into the Precambrian through one or two orders of magnitude (text-fig. 6).
The answer given by this (admittedly dubious) extrapolation is comparable to that obtained from the
molecular evidence. Such a date is also partly supported by new estimates of the diversity and
abundance of Precambrian and Cambrian stromatolites (Walter and Heys, in press; text-fig. 6); the
substantial decline in both diversity and abundance that began between about one billion and 800
million years ago is attributed to grazing by newly evolved metazoans.

Finally, some evidence of the time of origin of the metazoan phyla may also be obtained from
collagen molecules. The sequence data so far available are not ideal as they mostly come from animals
(birds and mammals) that have diverged relatively recently. Nevertheless, there is some indication
that the genes for Type I and Type III collagens diverged about 800-1000 million years ago (Bernard
et al. 1983; Runnegar, in press a). This event may well have occurred early in the history of the
Metazoa, but until more invertebrate or lower vertebrate sequences become available it will be
difficult to test this hypothesis and calibrate the collagen clock.

Comparative biochemistry and the origin and early evolution of the Metazoa

A different approach to the problem of the early history of the Metazoa has been explored by Towe
(1970, 1981). He has attempted to use the distribution of certain molecules in the living biota to
determine relationships between different distantly related groups of organisms. He suggested, for
example, that as collagen is limited to the Metazoa and requires molecular oxygen for its production
(Kikuchi et al. 1 983), the time of origin of fossilizable animals was determined by oxygen levels in the
atmosphere and hydrosphere (Towe 1970, 1981; Runnegar 1982b, c).

The molecular evidence for historical relationships between the animal phyla has not been
explored in any comprehensive way. In part, this is because there is too little information available,
but it is also due to the fact that no systematic study of the available data has yet been made. However,
it is possible to suggest some methods of approach and to identify some of the potentially useful
molecules.

Most genes contain many characters in addition to their primary structures (DNA sequences).
These characters include the position and nature of promoter sequences; the presence/absence
and size of signal and/or propeptides; the sizes and positions of exons, protein-coding regions,
and introns; the presence of tandem repeats or palindromes; and the position and nature of
polyadenylation signals. Similarly, each of the proteins specified by homologous genes may display
differences in their secondary or higher order structures, active-site ligands, hydrophobic regions,
etc. Each character is therefore of potential phylogenetic significance and may be analysed in a
cladistic fashion.

For example, at the time of his death, Tom Schopf was attempting to use the positions of the non-
coding sequences (introns) in the actin genes of eukaryotes to examine relationships between the
animal phyla (pers. comm. 10 February 1984). In vertebrate a and /3 actin genes the introns lie within
or adjacent to codons 41, 121, 150, 204, 267, and 327 (Nudel et al. 1983) and a similar arrangement is
found in sea urchin actin genes (codons 41, 121, 204, and 267). By contrast, arthropod and nematode
actin genes have introns in different positions. Thus, this evidence supports the close relationship of

RUNNEGAR: MOLECULAR PALAEONTOLOGY

17

echinoderms and vertebrates and suggests that uniramian arthropods, echinoderms/vertebrates, and
nematodes are equally distant.

Because small animals can respire by simple diffusion (Alexander 1971) they do not require
respiratory transport pigments. The evolution of these complexes must therefore post-date the origin
of the Metazoa and the evolution of collagen (which was needed to build bigger bodies). An
understanding of the evolutionary histories of the respiratory transport pigments should therefore
provide some insight into the early history of the Metazoa. For example, hemerythrin is an
intracellular non-haeme oxygen carrier that has Fe at the active site. It has been found in sipunculids,
priapulids. Lingula , and one annelid, but is only well known from the Sipunculida (Klotz el al. 1976).
A determination of the amino-acid sequence of lingulid hemerythrin (Joshi and Sullivan 1973) should
therefore provide important information about the relationship of the two phyla and their affinities
with the proterostomes and deuterostomes. Similarly, it would be a big help to have the amino-acid/
gene sequences of platyhelminth, nemertean, nematode and holothurian globins, and inolluscan
haemocyanins. This kind of information should become available within the next decade.

BIOMINERALIZATION AND MOLECULAR BIOLOGY

Many different kinds of organisms deposit crystalline or amorphous inorganic compounds inside or
outside their cells (Lowenstam 1981). These biominerals are frequently used to construct rigid
skeletons, but they are also used to strengthen flexible walls, to rid the cells of unwanted salts, to store
useful ions, or to form parts of sensory organs used for sight, orientation, and navigation. As the
formation and organization of biominerals occurs primarily at the molecular level, studies of the
production, construction, and preservation of mineral skeletons and other biominerals link
molecular biology with palaeontology and other branches of geology. For example. Riding (1982)
has suggested that the late Proterozoic-Jurassic fossil record of calcified marine cyanophytes may
reflect lower Mg/Ca ratios in sea water during that period (but see Sandberg 1983), and Cook and
Shergold (1984) have argued that the time of origin and composition of the skeletons of Cambrian
invertebrates are related to major changes in the concentration of phosphate in the shallower parts of
the early Cambrian oceans.

If these kinds of useful hypotheses are to be generated and tested, it will be necessary to understand
much more about the mechanisms and history of biomineralization. The generalization that
phosphate skeletons were common in the Cambrian and rare thereafter (Lowenstam and Margulis
1980) needs to be explored further through petrographic, SEM, and electron microprobe studies
of Cambrian fossils. In addition the recent discovery that original skeletal microstructures are
frequently replicated by phosphatic internal moulds (Runnegar and Bentley 1983; Runnegar 1983,
in press b) should make it possible to determine the nature and composition of carbonate skeletons in
which the original microstructures have been destroyed by recrystallization. There is already good
evidence that other fine-grained casting media (e.g. dolomitized micrite) may also yield excellent
replicas of original microstructures (J. Pojeta, Jr., pers. comm.).

It is possible to gain some insight into the molecular controls on skeletal construction by examining
skeletons formed from well-ordered crystalline subunits. If the crystalline subunits have a form or an
arrangement which is not found in natural crystals of the same mineral, it is fairly easy to identify the
effect— and perhaps the cause— of the biological control.

For example, natural inorganic crystals of calcite are known to develop some 328 different
crystallographic forms (Runnegar 1984c). However, most natural and synthetic crystals and many
biominerals display only the most common forms, normally low-index rhombohedra, and simple
prisms. In contrast the mica-like calcite folia of the window-pane shell Placuna placenta have their
surfaces constructed from the very rare rhombohedral form { 1 0l8} (Runnegar 1984c). This form lies
perpendicular to a direction of fast crystal growth and should not appear under normal conditions.
Its extreme development in P. placenta is therefore clearly under biological control, and probably
results from a two-dimensional stereo-chemical similarity between the mineral lattice and the

18

PALAEONTOLOGY, VOLUME 29

interleaved protein matrix; the array of calcium atoms in the { 1 0l8} plane of the calcite lattice
matches the inter-residue dimensions of a parallel (J-pleated sheet of a protein with a repetitive amino-
acid sequence of the form (glycine-aspartic acid)„ (Runnegar 1984c). Thus, the crystallography of
the mineral phase may, at least in principle, be used to determine something about the nature of the
adjacent organic matrix. It should, therefore, be possible to make the same kinds of deductions from
the skeletons of extinct organisms.

The organization of individual skeletal elements may also be informative. The coccosphere of the
"living fossil’ Braarudosphaera bige/owi is a regular dodecahedron formed of twelve equal-sized
pentaliths. Each pentalith is composed of five calcite crystals arranged in a highly organized way
(Runnegar, in press c). As pentagonal symmetry does not exist in the calcite lattice the assembly of the
pentaliths in the Golgi aparatus of the algal cells must be specified at the molecular level. If the
operation of such systems were well understood, it would again be possible to make some precise
deductions from the skeletons of extinct organisms.

Stefan Bengtson (pers. comm.) has pointed out that it would be useful to be able to distinguish
between collagen-mediated phosphate skeletons and those formed in other ways. So far as is known,
vertebrate bone and teeth are mineralized by the deposition of apatite within and between collagen
fibrils (Lees 1979; Holding et al. 1980; Glimcher 1984). On the other hand, phosphate deposition in
the muscles of the polychaete Nephtys (Gibbs and Bryan 1984) and the periostracum of the bivalve
Lithophaga (Waller 1983) obviously occurs in a fundamentally different manner. Are these various
modes of phosphatization distinguishable microscopically? Could we, for example, identify a
mineralized analogue of the graptolite periderm? These are the kinds of questions that need to be
answered if we are to understand the true nature of the phosphatic microfossils found in early
Cambrian strata.

Determination of genome sizes

Despite the difficulties of measurement there is considerable evidence that the genomic DNA content
(haploid content, C-value) of organisms is correlated with cell volume and nuclear volume (Cavalier-
Smith 1978). Thomson (1972) used this relationship to show that the abnormally high (diploid) DNA
contents of living lungfish (160-285 picograms per cell; Pedersen 1971) were developed slowly
throughout the evolutionary history of the lungfish. He based his analysis on measurements of the
dimensions of osteocyte lacunae in fossil bone. The osteocytes of Devonian lungfish were found to be
less than a tenth of the volume of the osteocytes of living lepidosirenid lungfish, and their DNA
content is therefore likely to have been comparable to that found in living mammals (3-5 pg per cell).
As most of the morphological innovations occurred early in the history of the group (Campbell and
Barwick 1983) the great increase in DNA content followed rather than caused the rapid evolution
of this group of organisms (Thomson 1972).

It would be useful to have more data of this kind to test the generalization that exceptionally large
amounts of DNA are found in the genomes of "living fossils’ (Hinegardner 1976). Such a correlation
may imply that the extra "junk' DNA somehow stifles evolutionary change (Thomson 1972) although
other explanations are also possible (Grime and Mowforth 1982).

The obvious problem for palaeontologists is the determination of cell size, but there is also a need
for more information from living organisms and for a more percise method of comparing estimates of
DNA content (Greilhuber et al. 1983). Measuring cell size is not difficult in permineralized plants, but
it is not easy to estimate the cell sizes of extinct animals. Nevertheless, there may be ways to tackle this
problem. The studies of Pawlicki (1984a, b ) on dinosaur bones show that osteocytes may be
spectacularly preserved; the fact that each shell prism of the secondary shell layer of living
rhynchonellid and terebratulid brachiopods is formed by a single epithelial cell (Williams 1 968) may
enable epithelial cell size to be determined in fossil brachiopods; and the report (Giraud-Guille 1984)
that the outlines of the epidermal cells of the crab are reflected in structures that penetrate the
cuticle may indicate that epidermal cell size can be measured in extinct arthropods. It remains to
be seen whether these and other ways of measuring cell size in fossil invertebrates will prove
to be practical.

RUNNEGAR: MOLECULAR PALAEONTOLOGY

19

CONCLUDING REMARKS

The idea that genome size may be reflected in the dimensions of the calcite prisms of the shells of
brachiopods may seem far-fetched but it leads to the question of how far up the morphological
heirarchy should we expect molecular structures to persist? I have already shown that the basic
organization of collagen genes is reflected in the cross-banding of collagen fibrils and that the
geometry of matrix proteins may control the most fundamental property of the shell of P. placenta. In
B. bigleowi the topology of a particular macromolecule (or set of macromolecules) appears to be
responsible for the design of the whole exoskeleton (Runnegar, in press c) and the same may be true
for most coccolith-bearing algae. Viewed in this way, there is no fundamental difference between
molecular biology and classical anatomy and it is important to try to integrate the knowledge of both
disciplines. Some of the recent results of developmental biology (Davidson et a/. 1982; Sanchez-
Herrero et al. 1985; Fjose et al. 1985) are providing the first steps in this direction.

There is also a need to bridge the gulf between molecular biology and classical population genetics
(Doolittle 1982) and a need for new general statements about the way evolution has occurred. We
know a great deal about the processes that lead to new species but rather little about the processes
that give rise to fundamentally new structures or new kinds of molecules (Jaanusson 1981 ; Runnegar
1984 b). It is not clear whether rapid rates or significant amounts of morphological change are
accompanied by comparable changes in the information content of the genome or whether the
information is merely rearranged in some way. Commenting on a similar point, Doolittle (1982,
p. 88) wrote; ‘We must disabuse ourselves of the notion that organisms considered “primitive”
because of their morphological and behavioural simplicity have primitive molecular biologies. Just
the opposite may well be true.’ And finally we know little of the role of gene transfer between
unrelated lineages in the development and diversification of life.

As one molecular biologist said to me recently, cytochrome c is a boring molecule; it has changed
little in billions of years (Dickerson 1980). By this he meant that the morphology of the molecule is
highly conserved; there are considerable differences in the messages of the genes encoding the protein
in different lineages. This apparent paradox is easily explained by the fact that there are so many
possible solutions to the same problem. There are about 100 amino-acid residues in an average-sized
molecule of cytochrome c, and only about three of these residues are fully conserved in the proteins so
far studied. If only one to two closely related amino acids could occupy each of the remaining sites,
there would still be about 2100 possible combinations. It is, therefore, obvious that there is enormous
scope for genomic evolution with little or no effect upon morphology. Thus, it is more important to
distinguish between the evolution of information and the evolution of molecular and anatomical
structures rather than to attempt to isolate ‘molecular evolution’ from phenomena observed at higher
morphological levels.

The current dogma of molecular evolution is essentially gradualistic; a succession of small changes
in the amino-acid sequences gradually converts one kind of protein into another. This mechanism
explains the evolution of closely related proteins but it does not adequately account for the origin of
fundamentally new kinds of enzymes. These may well arise by the fusion of parts of two or more
unrelated genes (Guiard and Lederer 1979; Runnegar 1 984/?); the new product may have a new
morphology and a new function and yet be specified by old information.

A striking example of the non-gradualistic evolution of a new enzyme is given by Ohno (1984).
Despite the fact that the industrial synthesis of nylon began only several decades ago, it was found in
1975 that a species of Flavobac ter ium could grow in a culture medium containing a by-product of
nylon factories (6-aminohexanoic acid cyclic dimer) as the sole source of carbon and nitrogen. Ohno
has suggested that the new enzyme arose by the insertion of a single nucleotide into the beginning of a
pre-existing protein-coding sequence. This insertion resulted in a change in the DNA reading frame
allowing the old information to be translated in a fundamentally new way.

Compared with the number of living and extinct species the number of extant and extinct enzymes
and other kinds of proteins is relatively small and many are widely shared amongst distant taxa. It is,
therefore, clear that the evolution of an important new kind of protein (e.g. collagen) has always been

20

PALAEONTOLOGY, VOLUME 29

a rare event. Given this fact, how likely is it that genes for useful proteins have been acquired by
lateral transfer from unrelated organisms?

The best possible example of this phenomenon is the presence of haemoglobin genes in leguminous
and non-leguminous angiosperms (Brisson and Verma 1982; Appleby et al. 1983; Kortt et al. 1985),
but, so far as is known, in no other plants. There is ample evidence that the plant haemoglobins are
homologous to animal globins (Runnegar 19846) and so there are two alternatives: either the
angiosperms inherited the gene from the common ancester of animals and plants and it remained
unexpressed for hundreds of millions of years or a haemoglobin gene was transferred from an animal
to an angiosperm some tens of millions of years ago.

The plant haemoglobins are restricted to nitrogen-fixing root nodules formed in a symbiotic
association with the bacterium Rhizobium. The haeme moiety appears to be manufactured by the
bacteroid whereas the protein is synthesized by the plant after bacterial infection has occurred
(Ellfolk 1972; Dilworth and Glenn 1984). The haemoglobin occurs in the cytoplasm and nucleus of
the infected cells but not in the bacteroids or the peribacteroid spaces (Robertson et al. 1984).

Given this highly specific and unusual association it is tempting to conclude that the angiosperms
have acquired the haemoglobin gene by lateral transfer. The difficulty with this interpretation results
from the fact that the amino-acid sequences of the angiosperm globins are about 80-90% different
from all animal globins so far sequenced. Thus, unless the angiosperm globins have been evolving at
a much faster rate than animal globins, the sequence differences indicate that the animal and plant
globins diverged about a billion years ago.

A faster rate of evolution is a distinct possibility given the substantial differences (up to 60%) in
the amino-acid sequences of different angiosperm globins (Kortt et al. 1985). However, another
possibility is that the ancestral plant globin gene was obtained from a member of an invertebrate
phylum such as the Nematoda. Until at least one globin sequence is available from a representative of
each of the phyla that could have contributed a globin gene to the angiosperms, it will be difficult to
exclude the possibility that the angiosperm genes were obtained through lateral transfer.

If such lateral gene transfers have occurred during the course of evolution, they may well represent
very rare events. However, given the length of geological time, even very rare events have a high
probability of occurrence. It is, therefore, important for students of evolution to consider the
implications of such rare events in the evolution and development of life. It may no longer be possible
to assume a priori that demonstrably homologous characters are necessarily confined to single clades.

Acknowledgements. I thank Maria Runnegar for much encouragement, advice, and help with the literature of
biochemistry. The computing and other technical assistance was provided by F. A. Shaw and the manuscript
typed by R. K. Vivian. Much of this work was supported financially by the Australian Research Grants Scheme.

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PALAEONTOLOGY, VOLUME 29

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BRUCE RUNNEGAR

Department of Geology and Geophysics
University of New England

Typescript received 1 5 March 1985 Armidale, New South Wales

Revised typescript received 21 June 1985 Australia, 2351

THE AMMONITE FAUNA OF THE CALCAIRE
A BACULITES (UPPER M A ASTRICHTI AN ) OF THE
COTENTIN PENINSULA (MANCHE, FRANCE)

by W. J. KENNEDY

Abstract. The Calcaire a Baculites of the Cotentin Peninsula, Manche, France, is a sequence of bioclastic
limestones occurring as isolated outliers resting unconformably on rocks of Precambrian to Cenomanian age.
Ammonites, chiefly Baculites , are locally abundant, and their taxonomy is revised. B. anceps Lamarck, 1822
dominates the fauna, with scarce Hoploscaphites constrictus ( J. Sowerby, 1817) and rare to very rare Pachydiscus
( Pachydiscus ) gollevillensis (d’Orbigny, 1850), P. (P.) jacquoti Seunes, 1890, P. (P.) sp., P. ( Neodesmoceras )
mokotibense Collignon, 1952, Anapachydiscus fresvillensis (Seunes, 1890), Hoplitoplacenticeras lasfresnayanum
(d’Orbigny, 1841), Glyptoxoceras sp., Diplomoceras cylindraceum (Defrance, 1816), B. vertebralis Lamarck
1801, Fresvillia constricta gen. et sp. nov., Hoploscaphites sp., and Acanthoscaphites verneuilianus (d’Orbigny,
1841).

Limited belemnite and echinoid data, published observations on bryozoans and forams, and the known
ranges of some of the key ammonites in the type area of the Maastrichtian and environs and in the White Chalk
facies of northern Europe all place the unit in the Upper Maastrichtian; the balance of evidence suggests it is
equivalent to the upper Belemnitella junior Zone and part of the Belemnella casimirovensis Zone. Some localities
extend very high in the casimirovensis Zone on the basis of the occurrence of late forms of H. constrictus (‘variety’
crassus of authors); there is no positive evidence for the Lower Maastrichtian from the ammonite fauna.

The stratigraphy and divisions of the Maastrichtian stage are in a state of flux, as the proceedings of
the recent colloquium on Cretaceous stage boundaries revealed (Birkelund and Surlyk (eds.) 1984:
see especially contributions by Kennedy; Schulz, Ernst, Ernst and Schmid; and Surlyk). The type
section at Maastricht in Holland is incomplete, with discontinuities separating Maastrichtian chalks
from the Campanian chalks below and Maastrichtian limestones from the Danian above. Even
where there are expanded successions with relatively diverse ammonite assemblages (in Denmark:
Birkelund 1979; Poland: Blaszkiewicz 1980; USSR: Atabekian 1979; Spain: Ward and Wiedmann
1983) there is little agreement on the range of many classic species or on the zonation of the stage.

The reasons for this are several. There is a dearth of Lower Maastrichtian ammonite assemblages
in Europe, and those that are known (e.g. in Galicia: Favre 1869; Styria: Hauer 1847, 1858) are not in
sequence; ammonites are rare in the widespread White Chalk facies that dominates the region; and
with the exception of Howarth’s (1965) study of Baculites anceps Lamarck, 1822, none of the types of
key taxa have been adequately revised since their initial description. The classic Lower Maastrichtian
fauna from Neuberg (Styria, Austria) first noted by Hauer ( 1 847, 1 858) is the subject of a forthcoming
paper (Kennedy and Summesberger, in press), while revision of the faunas of the Maastricht area is
under way (Kennedy 1984a and in prep.). The present contribution focuses on the third classic area
for Maastrichtian ammonites in western Europe: the Cotentin Peninsula in Manche, northern
France. The presence in this area of Cretaceous limestones rich in Baculites (see text-fig. 1 ) was first
noted by de Caumont (1824). Referred to as the Terrain a Baculites , Calcaire a Baculites , or Craie de
Valognes, the sequence was first correlated with the limestones of Maastricht by Hebert (1853) and a
Maastrichtian age is now generally attributed to it, although quite where it lies within this stage has
been disputed.

Ammonites from this unit were first described by James Sowerby, who introduced Scaphites
constrictus in 1817. Additional forms were described by Lamarck (1922), d’Orbigny (1840-1842),

[Palaeontology, Vol. 29, Part 1, 1986, pp. 25-83, pis. 1-16.|

26

PALAEONTOLOGY, VOLUME 29

text-fig. 1 . A, general location of the area. B, locality map showing the outcrop of the
Calcaire a Baculites in the Cotentin Peninsula, Manche, France, and some of the
commonly cited localities; note that there are no outcrops at Golleville.

Seunes (1890a, b, 1891), de Grosso uvre (1894), and Spath (1922a), including a series of key
Maastrichtian taxa. The most important collections were made by C. B. de Gerville in the first half of
the nineteenth century; specimens sent to James Sowerby in London, the Humboldt Museum in
Berlin, and the Naturhistorisches Museum in Vienna, as well as those described by d’Orbigny
( 1 840- 1 842) attest to the richness of his collection (lost in the destruction of Caen in 1 944). A search
of the major European museums has, however, revealed many hundreds of ammonites, mostly
Baculites , that form the basis of this revision.

The Calcaire a Baculites occurs as a series of outliers resting on rocks of Precambrian
to Cenomanian age (text-fig. 1). It was widely worked for building stone in the last century

KENNEDY: UPPER MAASTRICHT! AN AMMONITES

27

but few outcrops now remain, and the unit is best examined in the walls and gateposts of
the bourgeois mansions of the region. A few metres of yellow-weathering white bioclastic
tuffeau are still exposed below Veauville Farm at Fresville, near Valognes, but the inhabitants
are unwilling to permit access due to the depredations of collectors. The quarry south-west
of Golleville marked on the 1:80000 Saint-Lo sheet no longer shows a section. Temporary
exposures appear from time to time, but it is now impossible to determine a detailed succession in
the unit.

De Grossouvre (1901, pp. 285, 292) provides the best account of the sequence. He described a basal
conglomerate 0-2-0-3 m thick, overlain by bioclastic limestone. At Veauville he noted the following
details of a part only of the Calcaire a Baculites , which he believed to be 4-5 m in total thickness in the
Cotentin Peninsula:

‘Au-dessous du terrain Tertiaire, on observe:

Banc duravecfossiles rare .............. 0-33

Calcaire blanc crayeux, finement sableux, un peu noduleux a la partie superieure. On y trouve:
Belemnitella mucronata, Cidaris , sp., Nucleolites minimus , etc.; Brachiopodes nombreux; Rhycho-
nelles, Terebratules, Magas, Thecidees. . . . Les Baculites y sont rares et on y rencontre surtout
Scaphites constrictus ............... 030

Banc noduleux . . . . . . . . . . . . .010

Deux bancs durs compacts avec Baculites rares .......... 0-50

Sable calcaire . . . . . . . . . 0-15

Bancs durs ................. 0-50

Banc grumeleux a Catopygus, Salenia ............ 0-30

Bancs tres durs, compacts avec nombreux Baculites .......... 0-80

Fond de la carriere.

En dehors des Baculites tres nombreux dans certains bancs, la faune est composee principalement de
Lamellibranches; les Gastropodes sont tres rares. L’etude des diverses especes de ces deux classes est encore a
faire; malheureusement on ne trouve d’ordinaire que des moules assez mal conserves. Parmi les formes les plus
abondantes, je citerai seulement Trigonia , Gervillia, Ostrea.

Sur certains points, les Brachiopodes sont assez communs, ainsi que les Echinides.’

Granidor etal. (1967) suggest a total thickness of 15-20 m for the sequence, a much higher figure than
that given by de Grossouvre.

SYSTEMATIC PALAEONTOLOGY

Location of specimens. The following abbreviations are used to indicate the location of specimens mentioned
in the text: BMNH, British Museum (Natural History), London; EMP, Ecole des Mines Collections,
formerly in Paris but now in the Universite Claude-Bernard, Lyons; FSL, Faculte de Sciences, Universite
Claude-Bernard, Lyons; FSM, Faculte des Sciences, Le Mans; FSR, Faculte des Sciences, Rennes;
GBA, Geologische Bundesanstalt, Vienna; IRSNB, I nstitut Royal des Sciences Naturelles, Brussels; MHNG,
Museum d’Histoire Naturelle, Geneve; MNHH, Musee du Havre, Le Havre; MNB, Museum fur Naturkunde,
Berlin; MNHP, Museum National d’Histoire Naturelle, Paris; NHMW, Naturhistorisches Museum, Vienna;
OUM, University Museum, Oxford; SP, Collections of the Sorbonne, now in the Universite Pierre et Marie
Curie, Paris.

Suture terminology. The system of Wedekind (1916), as reviewed by Kullmann and Wiedmann (1970), is used
here. E = external lobe, L = lateral lobe, U = umbilical lobe, I = internal lobe.

Dimensions. All dimensions are given in millimeters; D = diameter, Wb = whorl breadth, Wh = whorl height,
and U = umbilicus; c = costal and ic = intercostal. Figures in parentheses refer to dimensions as a percentage of
diameter. The term rib index as applied to heteromorphs is the number of ribs in a distance equal to the whorl
height at the mid point of the interval counted.

Synonymies. Only citations which include illustrations of material or important systematic, stratigraphic, or
geographic information are included.

28

PALAEONTOLOGY, VOLUME 29

Order ammonoidea Zittel, 1884
Suborder ammonitina Hyatt, 1889
Superfamily desmocerataceae Zittel, 1895
Family pachydiscidae Spath, 1922c/

[nom. turns/. Spath, 1923, p. 39, for Pachydiscinae Spath, 1922c/, p. 132]

Genus pachydiscus Zittel, 1884

Type species. Ammonites neubergicus Hauer, 1858, p. 12, pi. 2, figs. 1-4, by the subsequent designation of de
Grossouvre (1894, p. 177).

Discussion. Kennedy and Summesberger (in press) have reviewed the type species and the genus. Two
subgenera are recognized: P. ( Pachydiscus ) with persistent ornament, and P. ( Neodesmoceras )
Matsumoto, 1 947, which is virtually smooth through most of its ontogeny. Both occur in the Calcaire
a Baculites ; Neodesmoceras was previously known only from the Maastrichtian of the Indo-Pacific
region (Madagascar, Japan, Alaska, and California).

Subgenus pachydiscus Zittel, 1884
[ = Parapachy discus Hyatt, 1900, p. 570; Joaquinites Anderson, 1958, p. 218]

Pachydiscus ( Pachydiscus ) gollevillensis (d’Orbigny, 1850)

Plates 1 -3; Plate 4, figs. 4-6; Plate 5, figs. 12 14, 20-24; Plate 1 1 , figs. 15; text-figs. 2, 3p, r, 4c

1841 Ammonites lewesiensis Mantell; d’Orbigny, p. 336 (pars), pi. 101, figs. 1-3; non pi. 102, figs. 1 and 2.
1 850 Ammonites gollevillensis d’Orbigny, p. 21 2 ( pars),
non 1857 Ammonites gollevillensis d’Orbigny; Sharpe, p. 48, pi. 17, fig. 2 ( = Pachydiscus sharpei Spath).
1861 Ammonites exilis Binkhorst, p. 31, pi. 6, fig. 4.

1891 Pachydiscus gollevillensis d’Orbigny, sp.; Seunes, p. 10, pi. 14 (5), figs. 1-3.

1894 Pachydiscus gollevillensis d’Orbigny, sp.; de Grossouvre, p. 214, pi. 29, fig. 4; pi. 31, fig. 9.
non 18976 Pachydiscus gollevillensis Orb.; Kossmat, p. 82, pi. 6, fig. 1 ( = Pachydiscus compressus Spath).
non 1 898 Pachydiscus gollevillensis Orb.; Kossmat, p. 97 ( 1 62), pi. 15(21), fig. 1 ( = Pachydiscus compressus
Spath).

1907 Pachydiscus gollevillensis d’Orb. sp.; Wisniowski, p. 196.

1908 Pachydiscus gollevillensis (d’Orbigny); de Grossouvre, p. 32, pi. 9, figs. 1 and 2.

non 1909 Pachydiscus sp. ind. ex aff. gollevillensis (d’Orbigny); Kilian and Reboul, p. 43, pi. 19, fig. 3; pi. 20,
fig. 1.

1913 Pachydiscus egertoni Forbes sp.; Nowak, p. 354, pi. 41, fig. 13; pi. 43, fig. 28; pi. 44, fig. 38.

1922 Pachydiscus {Parapachy discus) gollevillensis (d’Orbigny); Cottreau, p. 181 (73), pi. 17 (9), fig. 1.
1922 a Parapachydiscus valognensis Spath, p. 122.

1927 Pachydiscus Egertoni Forbes sp. var. gollevillensis d’Orb. sp.; Bohm, p. 217 (pars); non pi. 13,
fig. 2.

1929 Pachydiscus cf. gollevillensis d’Orbigny; Barrabe, p. 181, pi. 22 (8), fig. 14.

1930 Pachydiscus gollevillensis d’Orbigny; Besairie, p. 566, pi. 26, fig. 4.

1931 Pachydiscus gollevillensis d’Orbigny; Basse, p. 31. pi. 4, fig. 1; pi. 11, fig. 4.

71938 Parapachydiscus nov. sp. aff. chrishna Forbes- gollevillensis d'Orbigny; Collignon, p. 68 (18), pi. 1,
fig. 6.

non 1940 Pachydiscus aff. gollevillensis (d’Orbigny); Spath, p. 45, pi. 2, fig. 1 .

1951 Pachydiscus neubergicus Hauer var. nowaki Mikhailov, var. nov., p. 65.
non 1951 Pachydiscus gollevillensis d’Orbigny; Mikhailov, p. 66, pi. 8, fig. 39.

1959 Pachydiscus gollevillensis (d’Orbigny); Naidin and Shimanskij, p. 187, pi. 11, figs. 1 -3.
non 1963 Pachydiscus sp. no. 1 cfr. P. gollevillensis (d’Orbigny); Young, p. 56, pi. 8, fig. 5; pi. 1 7, fig. 5; text-
fig. 10c, o.

non 1963 Pachydiscus sp. no. 2 cfr. P. gollevillensis (d’Orbigny); Young, p. 56, pi. 13, figs. 1,2, 5; pi. 14,fig.4;
pi. 17, figs. 1 and 8; text-fig. 10//, g.

Pachydiscus sp. no. 3 cfr. P. gollevillensis (d’Orbigny); Young, p. 57, pi. 14, figs. 2 and 3; text-figs.
In , 8/?.

non 1963

KENNEDY: UPPER MAASTRICHT! AN AMMONITES

29

1964 Pachydiscus gollevillensis (d’Orbigny); Tsankov, p. 160, pi. 6, fig. 3; pi. 7, fig. 4; pi. 9, fig. 1 .

1969 Pachydiscus gollevillensis gollevillensis (d’Orbigny); Atabekian and Akopian, p. 4, pi. 1, fig. 1.

non 1969 Pachydiscus gollevillensis armenicus Atabekian and Akopian, p. 8, pi. 1, fig. 2; pi. 3, figs. 1 and 2.

1971 Pachydiscus gollevillensis d’Orb.; Collignon, p. 24, pi. 649, figs. 2402 and 2403; pi. 650, figs.

2404-2406.

1980 Pachydiscus gollevillensis nowaki Michailov, 1951; Blaszkiewicz, p. 45 (pars), pi. 35, figs. 2 and 3
only.

1982 Pachydiscus (Pachydiscus) gollevillensis (d’Orbigny); Martinez, p. 82, pi. 7, fig. 1.

1982 Pachydiscus gollevillensis gollevillensis (d’Orbigny, 1841); Tsankov, p. 36, pi. 1 5, fig. 2, ? figs. 1 and
3; pi. 16, fig. 2.

non 1982 Pachydiscus gollevillensis armenicus Atabekjan and Hacobjan, 1969; Tsankov, p. 37, pi. 16, figs. 3
and 4.

Types. This is a Prodrome species, introduced by d’Orbigny in 1850 as nomen novum for Ammonites lewesiensis
d’Orbigny (not Mantell): ‘*17. Gollevillensis , d’Orb. 1847. A. lewesiensis , d’Orb., 1842. Paleont. franc., Terr,
cret., pk 101 et 102, fig. 1 (non Sowerby). France, Golleville, Fresville (Manche)’ (d'Orbigny 1850, p. 212). In
Paleontologie Franqaise d’Orbigny (1841, p. 336, pi. 101; pi. 102, figs. 1 and 2) notes that de Gerville had found
the species at Golleville and Fresville.

The de Gerville Collection, formerly at Caen, was destroyed during the Second World War, while there are no
specimens from either of the above localities listed in the catalogue of the d’Orbigny Collection under A.
gollevillensis or lewesiensis. De Gerville sent ammonites from the Calcaire a Baculites to several of his
contemporaries; there are, for instance, specimens labelled in his distinctive style in the Museum fiir
Natiirkunde, Berlin, Naturhistorisches Museum, Vienna, and the British Museum (Natural History). In the case
of material sent to James Sowerby, one was described as A. constrictus in 1817, so dating the transaction some
twenty-four years earlier at minimum than publication of Paleontologie Franqaise and rendering it unlikely (but
not impossible) that the associated Pachydiscus in Sowerby’s Collection were studied by d’Orbigny and are
thus surviving syntypes. Because d’Orbigny’s protographs (reproduced here as text-fig. 2) represent at least
two species, and because the original of his plate 101 is sufficiently idealized to be interpretable as either
P. gollevillensis of authors or P. valognensis (Spath, 1922) for those who believe these species to be distinct,
neotype designation is desirable. BMNH C38179 (PI. 1, figs. 1-3) is so designated in the interest of nomen-
clatural stability; the specimen being from Fresville and one of the specimens sent to James Sowerby by
de Gerville.

Material. BMNH 50135 from Valognes, the holotype by monotypy of Parap achy discus valognensis Spath, 1922a
(PI. 2, figs. 1 -3); BMNH C38178 and C7065 1 (internal and external moulds) from Fresville (ex J. Sowerby, c.vde
Gerville Collection); MNHP unreg. (de Vibraye Collection) from Fresville; SP 19 from Golleville (the original of
Seunes 1891, pi. 14 (5), fig. 3; the repository given by Seunes is an error); EMP unreg., two specimens from
Fresville or Valognes (the originals of Seunes 1891, pi. 14 (5), figs. 1 and 2; the repository given by Seunes is an
error); SP unreg. from Fresville (the original of de Grossouvre 1894, pi. 31, fig. 9); FSR 12, a juvenile from
Fresville (Seunes Collection); MNHH 5856, from Port Filiolet, Picauville; MHNG, two unreg. specimens
(ex Pictet Collection) from Fresville; MNB no. Hi, from Valognes (ex de Gerville Collection).

D

Wb

Wh

Wb: Wh

U

SP19

49-1(100)

14-6(29-7)

20-9(42-6)

0-7

12-6(25-7)

105-0(100)

31-0(29-5)

42-0(40-0)

0-74

27-5(26-2)

BMNH C38179 (neotype)

112-7(100)

33-6(29-8)

49-5(43-9)

0-68

27-1(24-1)

BMNH 50135 at

101-5(100)

-(-)

43-5(42-9)

—

26-0(25-6)

EMP unreg. (Seunes, pi. 14 (5), fig. 1)

125-0(100)

33-0(26 4)

49-6(39-7)

0-67

30-0(24-0)

EMP unreg. (Seunes, pi. 14 (5), fig. 2)

75-3(100)

-(-)

32-9(43-7)

—

17-9(23-8)

BMNH C38178

51-0(100)

-(-)

23-0(40-3)

—

14-0(24-6)

Description. All specimens are internal moulds of phragmocones. No body-chambers known. Coiling
moderately involute, with small, shallow umbilicus comprising around 25% of diameter.

Umbilical wall low and rounded, whorl section compressed (whorl breadth to height ratio ranges from 0-67
to 0-75) with greatest breadth well below mid-flank (text-fig. 3p, r). Inner flanks broadly rounded, outer flanks
flattened and convergent, ventrolateral shoulders broadly rounded, venter flattened.

30

PALAEONTOLOGY, VOLUME 29

c

text-fig. 2. Copies of d'Orbigny’s (1842) protographs of Ammonites lewesiensis , which he renamed A. golle-
villensis in 1850. a-c, copies of his plate 101, figs. 1-3 which correspond to the generally accepted view of the
species, d, e, copies of his plate 102, figs. 1 and 2, here interpreted as Pachydiscus ( Pachydiscus ) jacquoti Seunes,

1890«. All figures reproduced at original size.

EXPLANATION OF PLATE 1

Figs. 1-3. Pachydiscus ( Pachydiscus ) gollevillensis (d’Orbigny, 1850), BMNH C38179, neotype, from Upper
Maastrichtian Calcaire a Baculites of Fresville, Manche, France, x 1 .

•* A '

PLATE 1

KENNEDY, Pachydiscus ( Pachydiscus )

32

PALAEONTOLOGY, VOLUME 29

text-fig. 3. Whorl sections, a-d, Baculites vertebralis Lamarck, 1801. a, BMNH C70591; b, NHMW 7460; c,
MHNG unreg. (Pictet Collection); d, BMNH C70592. e-h, B. anceps Lamarck, 1822. e, NHMW 7482; f-h,
MHNG unreg. (Pictet Collection), i-l, Diplomoceras cylindraceum (Defiance, 1816). i, BMNH C37027;
j, FSR 4; k, MHNG unreg. (Pictet Collection); l, FSR 5. m, n, q, Anapachydiscus fresvillensis (Seunes, 1890a),
based on BMNH C524. o, s, Pachydiscus ( Pachydiscus ) jacquoti (Seunes, 1890a). o, BMNH C38 1 75; s, BMNH
C38177. p, r, P. (P.) gollevillensis (d’Orbigny, 1850). p, BMNH C38179; r, BMNH C38178.

KENNEDY: UPPER MAASTRICHT! AN AMMONITES

33

10 mm

text-fig. 4. External sutures, a, Ancipachydiscus fresvillensis (Seunes, 1 890a), BMNH C524. b, Pachydiscus
{P achy discus) jacquoti Seunes, 1890a, BMNH C38175. c, P. (P.) gollevdlensis (d’Orbigny, 1850), MHNG unreg.

(Pictet Collection).

Shell smooth to a diameter of 16 mm (PI. 5, hgs. 20 and 21; PI. 11, fig. 1); first ornament to appear is small
umbilical bullae (PI. 5, fig. 13; PI. 11, figs. 2 and 3), which give rise to feeble llexuous prorsiradiate ribs and striae
that generally efface on outer flank, although in some specimens there are feeble ribs and depressions on venter
(PI. 1 1, fig. 2). This stage persists to a diameter of 40 mm (PI. 5, figs. 1 3 and 22; PI. 1 1 , figs. 4 and 5), beyond which
strong ventral ribs appear. From this point to maturity (Pis. I -3; PI. 4, figs. 4 -6) there are nine to eleven umbilical
bullae per whorl. These arise as low swellings on umbilical wall, strengthen over the shoulder, and are elongate,
crescentic, and of variable strength within (e.g. PI. 3, fig. 2) and between individuals (compare PI. 1 and PI. 3,
figs. 1-3). Where strongly developed they extend as ribs across inner flank before declining (PI. 3, fig. 2); in some
cases they appear to subdivide across outer flank (PI. 3, fig. 4) with secondary ribs intercalated (PI. 3, figs. 2 and
4). In other specimens (PI. 1, fig. 2; PI. 2, fig. 2; PI. 4, fig. 5) ornament is virtually effaced at mid-flank. In all
specimens, ribs strengthen on ventrolateral shoulder, where they are distinctly prorsiradiate, blunt, and
rounded, and separated by slightly wider interspaces. All ribs pass straight across venter, and are interrupted by
narrow groove marking siphonal line. There are approximately eighty ventral ribs corresponding to the nine to
eleven umbilical bullae.

Suture line deeply and intricately subdivided, with symmetrically bifid saddles and markedly retracted
umbilical lobe (text-fig. 4c).

34

PALAEONTOLOGY, VOLUME 29

Discussion. The neotype is a specimen according well with the figures of Seunes (1891) and de
Grossouvre (1894). It is generally comparable with d’Orbigny’s pi. 101, which most authors have
used as a basis for the species, whereas d’Orbigny’s pi. 102, figs. 1 and 2 are obviously a juvenile
P achy discus jacquoti Seunes, 1 890c/.

P. valognensis (Spath, 1922a), the holotype of which is figured for the first time as Plate 2, is
inseparable from P. gollevillensis. P. neubergicus nowaki Mikhailov, 1951 (p. 65) is based on the
original of Nowak ( 191 3, p. 354, pi. 41, fig. 1 3); it has a somewhat coarser ventral ornament, but 1 can
see no criteria on which to separate it specifically from P. gollevillensis. Blaszkiewicz (1980, p. 45, pi.
35, figs. 1 -3, 9) differentiates it from P. gollevillensis sensu stricto on the basis of the more numerous
umbilical bullae, wider umbilicus, and more conspicuously reduced costulation in the central parts of
the sides. The original of his pi. 35, figs. 1 and 9 bears little resemblance to the gollevillensis group,
however. P.g. armenicus Atabekian and Akopian, 1969 (p. 8, pi. l,fig. 2; pi. 3, figs. 1 and 2) from the
Maastrichtian of Armenia has many more umbilical bullae (sixteen to twenty) than the present
material (nine to eleven) and sixty-two to seventy-three ventral ribs. It seems distinct enough from the
material described here.

P. gollevillensis is a close ally and, I believe, a descendant of the older P. neubergicus (Hauer, 1858)
(p. 12 (pars), pi. 2 (3), figs. 1-3 only), the lectotype of which is illustrated in Plate 4, fig. 3. This
species has 50% more umbilical bullae than P. gollevillensis , primary ribs that extend across the
flank and hi- or trifurcate on the ventrolateral shoulder, far fewer ventral ribs, and a wider
umbilicus. Evolution thus involved a reduction in the number of umbilical bullae, effacement of
lateral ornament, and an increase in number and decrease in strength of ventral ribs. It is thus
perfectly possible that P. g. armenicus may be an intermediate stage in this sequence which has
attained the finer ventral ornament of gollevillensis while retaining the style of umbilical ribbing
of neubergicus.

Occurrence. Calcaire a Baculites , Upper Maastrichtian of Fresville, Golleville, ‘Valognes’ and Port Filiolet,
Picauville, Manche, France; Homines Morts, Lleida, Spain; Poland, north Germany, Austria, Armenian SSR,
northern Caucasus, Crimea, Bulgaria, the Bithynian Peninsula, Turkey, and Madagascar.

Pachydiscus ( P achy discus ) jacquoti Seunes, 1 890a
Plate 5, figs. 3-11, 15-19; Plate 6; text-figs. 2d, e, 3o, s, 4b.

1841 Ammonites lewesiensis , Sowerby; d’Orbigny, p. 336 (pars), pi. 102, figs. 1 and 2.

1850 Ammonites gollevillensis d’Orbigny, p. 212 (pars).

1861 Ammonites colligatus Binkhorst, p. 25 (pars), pi. 6, fig. 3 a-f (?); pi. 7, fig. 2a, b only.

1890a Pachydiscus Jacquoti, Seunes, 1888; Seunes, p. 5, pi. 3 (2), figs. 1-3.

18906 Pachydiscus Jacquoti, Seunes; Seunes, p. 237, pi. 9, figs. I -4.

1891 Pachydiscus Jacquoti, Seunes; Seunes, p. 9, pi. 12 (3), fig. 4.

1894 Pachydiscus neubergicus, F. von Hauer, sp. emend., A. de Grossouvre; de Grossouvre, p. 207
(pars), pi. 26, fig. 3; pi. 38, fig. 3.

1908 Pachydiscus neubergicus v. Hauer, sp. emend, de Gross.; de Grossouvre, p. 30, pi. 9, figs. 3 and 4.

1938 Pachydiscus neubergicus v. Hauer var. Jacquoti Seunes; Collignon, p. 48 (98), pi. 11, fig. 1 .

71952 Pachydiscus cf. P. jacquoti Seunes, 1890; Usher, p. 72, pi. 11, figs. 1-3; pi. 31, fig. 1.

EXPLANATION OF PLATE 2

Figs. 1-3. Pachydiscus (Pachydiscus) gollevillensis (d’Orbigny, 1850), BMNH 50135, holotype of previously
unfigured Parapachy discus valognensis Spath, 1922a, from Upper Maastrichtian Calcaire a Baculites of
Valognes, Manche, France, x 1.

PLATE 2

KENNEDY, Pachydiscus ( Pachydiscus )

36

PALAEONTOLOGY, VOLUME 29

1969 Pachydiscus egerloni jacquoti Seunes; Atabekian and Akopian, p. 9, pi. 1 , fig. 3; pi. 2, fig. 2; pi. 4,
fig. 1.

1971 Pachydiscus jacquoti Seunes; Collignon, p. 36, pi. 655, figs. 2412 and 2413.

Types. Seunes figured three specimens (1890«, pi. 3 (2), figs. 1 -3) and mentioned a series of other specimens from
the Pyrenees-Occidentales (now Pyrenees-Atlantiques) (possibly those figured by him in 18906, pi. 9, figs. 1 -4) as
well as a specimen from north-west of Alcoy, Alicante, Spain; all are syntypes of the species. I have been unable
to trace the original of his pi. 3 (2), fig. I , which was in the Janet Collection, nor the original of his pi. 3 (2), fig. 2,
said to be in the EMP Collections. The original of his fig. 3 survives in the latter collection (unreg.) but is the
smallest of the three (PI. 9, fig. 7) and does not show the characteristic adult features of the species. 1 hesitate to
designate a lectotype in these circumstances. If the original of Seunes ( 1 890c/, pi. 3 (2), fig. 1 ) is located, it should
be designated lectotype.

Material. BMNH C38175 from Fresville; BMNH C38177 and C70625, parts of the same specimen but labelled
‘Fresville’ and ‘near Valognes’ respectively (all J. Sowerby, ex de Gerville Collection); FSR 7 from Fresville
(Seunes Collection); FSR 8-10, labelled ‘Manche’. The original of Seunes (1891, pi. 12(3), fig. 4), originally in the
de Lapparent Collection (formerly in the Institute Catholique, Paris), has not been traced.

Dimensions

D

Wb

Wh

Wb: Wh

U

BMNH C38175

ic

122-0(100)

45-2(37-1)

49-9(40-9)

0-91

39-2(32-1)

at diameter

c

94-0(100)

36-6(38-9)

38-0(40-4)

0-96

29-9(31 8)

BMNH C38177

c

49-0(100)

19-0(38-7)

18-3(37-8)

1-02

16-0(32-7)

at diameter

ic

32-6(100)

13-7(42-0)

12-0(36-8)

114

10 0(30-7)

FSR 7

c

30-4(100)

12-9(42-4)

12-0(39 4)

1-08

9-8(32-2)

Description. All specimens are internal moulds of juvenile phragmocones; no adult body-chambers are known
from the Cotentin. Coiling moderately evolute (U = 30-7-32-7%), whorls expanding slowly. Umbilicus shallow,
with rounded, outwards-inclined wall. Umbilical shoulder broadly rounded, inner flanks broadly rounded,
outer flanks flattened and convergent, venter broadly rounded. Whorl section slightly depressed intercostally up
to a diameter of 70 mm, thereafter slightly compressed. Greatest breadth at umbilical bullae at all diameters.

Shell initially smooth (PI. 5, figs. 15 and 19). Weak umbilical bullae, four per half whorl, first appear at a
diameter of 12 mm, and are only ornament up to diameter of 35-45 mm (PI. 5, figs. 9-11; PI. 9, fig. 7) where they
number up to eight per whorl. Ornament thereafter (Seunes 1890n, pi. 2 (3), fig. 2; de Grossouvre 1894, pi. 26,
fig. 3) shows bullae elongating into pairs of narrow and distant prorsiradiate ribs; shorter intercalated ribs also
appear. Overall rib density increases, with thirteen or fourteen bullae at a diameter of 70 mm (PL 6, fig. 2) and
twice this number of ribs at ventrolateral shoulder. Ribs weaken over venter, interrupted by a narrow groove
over siphonal line.

Secondary ribs decline beyond 90 mm, and in largest specimen seen (PI. 6) there are fifteen umbilical bullae at
122 mm diameter which become progressively wider spaced over last half whorl, where they give rise to single
ribs that decline on flank and virtually disappear over venter. Secondary ribs weaken and eventually disappear
by same diameter. What I take to be the adult body-chamber (Seunes 18906, pi. 9, fig. 4) has distant primary ribs
only.

Suture (text-fig. 4b) is intricately subdivided, with large external lobe, deep E, large asymmetrically bifid E/L,
deeply incised bifid L and U2, and smaller asymmetrically bifid L/U2.

Discussion. De Grossouvre ( 1 894, p. 207) erred in uniting this species with P. neubergicus Hauer, 1 858
(PI. 4, fig. 3), which has a compressed oval whorl section when juvenile. Although also ornamented by
umbilical bullae which give rise to primary ribs only, these are coarser, blunter, and more numerous.
In middle growth, as represented by the lectotype (Hauer 1858, p. 12 (pars), pi. 2, figs. 1-3 only) (see
PI. 4, fig. 3), Hauer’s species is more involute, with more numerous primary ribs and bullae and many

EXPLANATION OF PLATE 3

Figs. 1-4. Pachydiscus ( Pachydiscus ) gollevillensis (d’Orbigny, 1850), from Upper Maastrichtian Calcaire a
Baculites of either Fresville or Valognes, Manche, France. 1-3, EMP unreg., heavily restored in plaster;
original of Seunes ( 1 891, pi. 14(5), fig. 1). 4, EMP unreg.; original of Seunes (1891, pi. 14 (5), fig. 2). All x 1.

PLATE 3

KENNEDY, Pachvdiscus ( Pachydiscus )

38

PALAEONTOLOGY, VOLUME 29

short secondaries and intercalatories on ventrolateral shoulders and venter. At maturity, topotypes
of P. neubergicus lose all but umbilical bullae and primary ribs that efface on the outer flank. P.
jacquoti is much more evolute and coarser ribbed than P. gollevillensis , and lacks the fine, dense,
ventral ribbing of that species. It should be noted that d’Orbigny’s smaller figured specimen (1841,
pi. 102, figs. 1 and 2) is a juvenile jacquoti.

Perhaps the closest ally of P. jacquoti is P. egertoni (Forbes, 1846a) (p. 108, pi. 9, fig. 1), of which
P. ganesa (Forbes, 1846a) (p. 103, pi. 7, fig. 8) is a synonym. The type material is from the
Maastrichtian Valudayur Beds of Pondicherry, southern India, and the specimen figured by Forbes
(BMNH C51038) is here designated lectotype. The species differs from P. jacquoti (which Atabekian
and Akopian 1969 regarded as no more than subspecifically distinct) in having weaker ornament
(effaced on the venter), a smaller umbilicus, higher compressed whorls with strongly convergent
flanks, and a narrow arched venter with ornament declining from a much smaller diameter.
Kossmat’s specimen (1898, p. 94 (159), pi. 15 (21), fig. 4a-c) may be a jacquoti, however.

P.j. australis Henderson and McNamara, 1985 (p. 76, pi. 8, figs. 1, 2, 7-10; text-figs. 12a, 136, 14,
1 5a) is a coarser ribbed form that retains its secondary ribs to a large diameter (see also Wetzel 1 930,
p. 85, pi. 1 3, fig. 2).

Occurrence. Calcaire a Baculites, Upper Maastrichtian, of Fresville, Manche, France; Upper Maastrichtian
Marnes de Nay of Gan-Rebaneq, Pyrenees-Atlantiques, France; Upper Maastrichtian of Kunraed, Holland;
Maastrichtian of Armenia, Madagascar, perhaps British Columbia, and southern India.

P achy discus (P achy discus) sp.

Plate 5, figs. 1 and 2

1890a Pachydiscus colligatus, Binkhorst sp.; Seunes, p. 6, pi. 3 (2), fig. 4.

Material. The original of Seunes (1890a, pi. 3 (2), fig. 4), from Fresville; EMP unregistered.

Discussion. This slowly expanding juvenile P. (Pachydiscus) with depressed whorl section and
numerous low, narrow, alternately long and short ribs differs from all other specimens from the
Calcaire a Baculites. Seunes referred it to Ammonites colligatus without hesitation, comparing it to
Binkhorst’s (1861) pis. 7 and 8a; Binkhorst’s figures show several species of pachydiscid, and the
present specimen is certainly not conspecific with those mentioned by Seunes. It is left in open
nomenclature at this time.

Occurrence. As under Material.

Subgenus neodesmoceras Matsumoto, 1947 (republished in English, 1951)

[ = Neodesmoceras Matsumoto, 1938, p. 193, nom. nud.\

Type species. P. ( Neodesmoceras ) japonicus Matsumoto, 1947, p. 39, by original designation.

EXPLANATION OF PLATE 4

Figs. 1 and 2. Diplomoceras cylindraceum (Defiance, 1816), BMNH C70644 (ex J. Sowerby, ex de Gerville
Collection), from near Valognes.

Fig. 3. Pachydiscus (Pachydiscus) neubergicus (Hauer, 1858), GBA 1858.01.6, lectotype, from Maastrichtian of
Neuberg, Styria, Austria; original of Hauer (1858, pi. 2, figs. 1-3).

Figs. 4-6. P. (P .) gollevillensis (d’Orbigny, 1 850), EMP unreg., from Fresville; original of de Grossouvre (1894,
pi. 31, fig. 9).

All except fig. 3 from Upper Maastrichtian Calcaire a Baculites of Cotentin Peninsula, Manche, France. All x 1 .

PLATE 4

KENNEDY, Diplomoceras , Pachydiscus ( Pachydiscus )

40

PALAEONTOLOGY, VOLUME 29
Pachydiscus ( Neodesmoceras ) mokotibense Collignon, 1952
Text-fig. 5

1952 Neodesmoceras mokotibense Collignon, p. 81, pi. 28, fig. 2.

1955 Neodesmoceras mokotibense Collignon; Collignon, p. 75, pi. 27, fig. 2.

1971 Neodesmoceras mokotibense Collignon; Collignon, p. 32, pi. 653, fig. 2410.

Type. Holotype by original designation is the original of Collignon (1952, pi. 28, fig. 2; 1955, pi. 27, fig. 2), from
the Maastrichtian of Mokotibe, Madagascar. There are also four paratypes, all in the EMP Collections.

Material. SP unreg., from the Fosse de la Bonneville.

Description. The specimen is a wholly septate internal mould some 140 mm in diameter. Coiling involute,
umbilicus comprising approximately 20% of diameter. Whorl section as broad as high. Inner flanks broadly
rounded, outer flanks flattened, convergent, ventrolateral shoulder and venter broadly rounded. There are traces
of narrow, distant ribs on outer flank and venter at smallest diameter visible, thereafter lost.

Suture line intricately subdivided.

Discussion. Neodesmoceras covers a range of Pachydiscus in which ornament is lost at an early stage,
leaving the shell almost smooth. The present specimen is the first European representative of the
subgenus, previously known only from the Indo-Pacific region (Madagascar, Zululand, Japan,
Alaska, California). Its nearly equidimensional whorl section easily distinguishes it from P. (N.)
japonicus , P. ( N .) obsoletiformis Jones, 1963 (p. 40, pi. 26, figs. 1, 4-8; pis. 27 and 28; text-figs. 20 and
22a), P. (N.) gracilis Matsumoto, 1979 (p. 60, pi. 10, figs. 1 -3; pi. 1 1, fig. 1; pi. 12, fig. 2; text-fig. 6), and
P. (N.) catarinae (Anderson and Hanna, 1935) (p. 19, pi. 11, fig. 1; pi. 2, fig. 1; pi. 3, figs. 1-3).
Its overall proportions correspond to those of P. ( N .) mokotibense Collignon, 1952 (p. 81, pi. 28,
fig. 2; republished by Collignon 1955, p. 75, pi. 27, fig. 2; see also Collignon 1971, p. 32, pi. 653,
fig. 2410), while comparison with the types (EMP unreg.) and Zululand specimens referred to
the species (BMNH C90 180-90 189) confirms this view. In particular the African material shows
periodic distant ventral ribs during early growth, as is seen in the present specimen at the smallest
diameter visible.

Occurrence. Upper Maastrichtian, Calcaire a Baculites of the Fosse de Bonneville, Manche, France.
Maastrichtian of Madagascar and Zululand.

Genus anapachydiscus Yabe and Shimizu, 1926
[ = Neopachy discus Yabe and Shimizu, 1926, p. 1 87]

Type species. Parapachydiscus fascicostatus Yabe, 1921, p. 57 (5), pi. 8(1), fig. 5; pi. 9 (2), figs. 2-5, by original
designation.

EXPLANATION OF PLATE 5

Figs. 1 and 2. Pachydiscus (Pachydiscus) sp., EMP unreg.; original of Seunes (1890a, pi. 3 (2), fig. 4).

Figs. 3-11, 15-19. P. (P.) jacipioti Seunes, 1890a. 3-5, 9-1 1, BMNH C38177 (ex J. Sowerby, ex de Gerville
Collection). 6-8, FSR8 (ex Seunes Collection). 15-17, FSR9 (ex Seunes Collection). 18 and 19, FSR7 (ex
Seunes Collection).

Figs. 12-14, 20-24. P. (P.) gollevillensis (d’Orbigny, 1850). 12-14, BMNH C38178 (ex J. Sowerby, ex de
Gerville Collection). 20 and 21, MHNH 5856. 22, BMNH C38179 (ex J. Sowerby, pjc de Gerville Collec-
tion), part of inner whorl of neotype (see also PI. 1); 23 and 24, EMP unreg.; original of Seunes (1891,
pi. 14 (5), fig. 2).

All from Upper Maastrichtian Calcaire a Baculites of Fresville, Manche, France, except figs. 20 and 21 which are
from Port Filiolet, Picauville, Manche, France. All x 1.

PLATE 5

m;fA

* 'f ' f ■ V

KENNEDY, Pachydiscus ( Pachydiscus )

42

PALAEONTOLOGY, VOLUME 29
Anap achy discus fresvillensis (Seunes, 1890«)
Plates 7 and 8; Plate 9, figs. 1 -3; text-figs. 3m, n, q, 4a

1861 Ammonites colligatus Binkhorst, p. 25 (pars), pi. 6, fig. 3 a-/(?); pi. 7, fig. 2c; pi. 8, figs. 1 and 2.
1 890« P achy discus fresvillensis Seunes, p. 3, pi. 2 (1), fig. 1.

18906 Pachydiscus fresvillensis Seunes; Seunes, p. 236, pi. 7, fig. 1; pi. 8, figs. 1-3.

text-fig. 5. Pachydiscus (Neodesmocer as) mokotibense Collignon, 1952, SP unreg., from Upper Maastrichtian
Calcaire a Baculites of the Fosse de la Bonneville, Manche, France, x 1.

EXPLANATION OF PLATE 6

Figs. 1-3. Pachydiscus (Pachydiscus) jacquoti (Seunes, 1890a), BMNH C38175 (ex J. Sowerby, ex de Gerville
Collection), from Upper Maastrichtian Calcaire a Baculites of Fresville, Manche, France, x 1.

PLATE 6

KENNEDY, P achy discus ( Pachydiscus )

44

PALAEONTOLOGY, VOLUME 29

71890/) Pachydiscus auritocostatus Schliiter, sp.; Seunes, p. 239, pi. 8, fig. 4 ( non Schliiter).
non 1891 Pachydiscus fresvillensis Seunes; Seunes, p. 14, pi. 12 (3), fig. 1.

1 894 Pachydiscus co/ligatus von Binkhorst, sp. emend. A. de Grossouvre; de Grossouvre, p. 202 (pars),
pi. 24, figs. 1 and 3 only (non pi. 33, fig. 1 ).

1895 Pachydiscus Quiriquinae Phillipi; Steinmann, p. 74, pi. 6, fig. 3; text-fig. 5.

1895 Pachydiscus Fresvillensis Seunes; Steinmann, p. 77.

1906 Pachydiscus supremus Petho, p. 88, pi. 5, fig. 1.

1908 Pachydiscus colligatus , Binkhorst van den Binkhorst sp. emend, de Gross; de Grossouvre, p. 28
(pars), pi. 4, figs. 1-3; pi. 5, fig. 1; pi. 6, fig. 1.

71930 Pachydiscus sumneri Maury, p. 155, pi. 13, figs. 1 and 2.

71930 Para pachydiscus poseidon Maury, p. 155, pi. 15.

71930 Canadoceras riogramense Maury, p. 169, pi. 21, fig. 2.

1930 Parap achy discus sp. indet. Wetzel, p. 86, pi. 14, fig. 1 .

1938 Parapachydiscus fresvillensis Seunes; Collignon, p. 101 (51), pi. 7, figs. 4 and 5; text-figs. O and P.
71952 Pachydiscus sp. aff. colligatus van Binkhorst; Collignon, p. 79, pi. 26, fig. 2.

71955 Pachydiscus sp. aff. colligatus van Binkhorst; Collignon, p. 74, pi. 26, fig. 2.

1969 Pachydiscus colligatus fresvillensis Seunes; Atabekian and Akopian, p. 13, pi. 6, fig. 1 .

1971 Pachydiscus fresvillensis Seunes; Collignon, p. 30, pi. 652, fig. 2408.

1985 Pachydiscus (Pachydiscus) fresvillensis Seunes, 1890; Henderson and McNamara, p. 78, pi. 8, figs.
3-6; pi. 9, figs. 1 and 2; text-figs. 126, 13a, 156.

Type. Lectotype, here designated, EMP A1 186, the original of Seunes (1890«, p. 3, pi. 2 ( 1 ), fig. 1), from Fresville.

Material. BMNH C524 (referred to by Spath 1921. p. 265) and C70653, from near Valognes.

Dimensions

EMP All 86 (lectotype)
BMNHC524 ’ ic
at diameter ic

at diameter c

D

148 0(100)
123 0(100)
1060(100)
67-8(100)

Wb

72-0(48-6)

-(-)

50-0(47-2)

36-3(53-5)

Wh

77-0(52-0)

59-0(48-0)

49-5(46-7)

32-3(47-6)

Wb: Wh
0-94

1 -01
M2

U

31-0(21 1)
25-6(20-8)
21-0(19-8)
15-2(22-4)

Description. All specimens studied are internal moulds of macroconch phragmocones, 67 148 mm in diameter.
Coiling involute, umbilicus comprising 19-8-22-4% of diameter with 60% of previous whorl covered. Whorl
section depressed, reniform in juvenile (breadth to height ratio up to 1-12) with greatest breadth at umbilical
shoulder, umbilical wall rounded and undercut, inner flank rounded, outer converging to broadly rounded
venter. Whorl breadth to height ratio decreases through ontogeny and section is slightly compressed from
120-130 mm diameter. Up to 60-65 mm (PI. 9, figs. 1-3), ten or eleven low, broad ribs arise at umbilical seam
and develop into prominent umbilical bullae. These give rise to paired (rarely three) ribs, while occasional
non-tuberculate ribs arise at shoulder and shorter intercalatories arise on inner flank to give a total of thirty-one
or thirty-two ribs per whorl. These are narrow and prorsiradiate on inner flank at smallest diameter visible, curve
forwards over ventrolateral shoulder and cross venter in broad convexity, attenuating and effacing over mid-
venter. As size increases (PI. 8) ribs strengthen and are strongest over venter by a diameter of 50 mm. Bullae
decline beyond 60-65 mm and migrate out to inner flank position ( PI. 8, fig. 2), giving rise to pairs of ribs with, in
addition, both long and short intercalatories that strengthen markedly over venter; there are forty ribs at
1 15 mm. Umbilical bullae decline beyond 120 mm and ribs progressively efface on inner and middle flank so that,
by largest diameter seen in the present material (the lectotype; PI. 7), ornament is confined to coarse, broadly
convex, rounded ribs, forty per whorl, on ventrolateral shoulders and venter only, with smooth flanks on mould
at least.

The suture (text-fig. 4a) is finely subdivided.

Discussion. Massive whorls, depressed and with strong umbilical bullae giving rise to groups of ribs,
plus the effacement of ornament on all but the ventrolateral shoulders and venter in middle growth

EXPLANATION OF PLATE 7

Figs. 1 and 2. Anapachydiscus fresvillensis (Seunes, 1 890a), EMP unreg., holotype, from Upper Maastrichtian
Calcaire a Baculites of Fresville, Manche, France; original of Seunes (1890a, pi. 2 (1), fig. 1), x 1.

PLATE 7

* s>

KENNEDY, Anap achy discus

46

PALAEONTOLOGY, VOLUME 29

readily distinguish macroconch A. fresvillensis from the other pachydiscids present in the Calcaire a
Baculites. Most workers refer the species to Pachydiscus, but the massive, involute whorls and the
presence of umbilical spines and tubercules giving rise to paired ribs suggest it is better placed in
Anap achy discus. Of the European species, the present form has generally been confused with
P. colligatus (Binkhorst, 1861). This species is discussed at length elsewhere in my revision of the
ammonites of the type Maastrichtian (in prep.). Suffice it to say that the proposed lectotype (the
original of Binkhorst 1861, pi. 8, which is also the holotype by monotypy of P. vandenbroecki de
Grossouvre, 1894, p. 207) is a much less massive shell, more evolute, and slower expanding;
moreover, on moulds, the primary ribs extend to the umbilical shoulder and the secondaries extend
well down the flank at a diameter where they have disappeared in P. {P.) fresvillensis , while the ventral
ribbing is much more subdued in middle growth. The smallest topotype of P. (P.) colligatus seen is
over 200 mm in diameter, so that comparison of the early stages is difficult. The reader is referred to
the revision of the Maastricht fauna noted above for additional discussion. P. quiriquinae Steinmann,
1895 (p. 74, pi. 6, fig. 3; text-fig. 5) from the Upper Maastrichtian of Quiriquina Island, Chile
(lectotype, here designated, the original of Steinmann 1 895, pi. 6, fig. 3) has the following dimensions
(after Steinmann):

D Wb Wh Wb:Wh U

Lectotype 285(100) 1 12(39-2) 145(50-9) 0-77 51(17-9)

Paralectotype 239(100) 110(46) 120(50-2) 0 91 40(16-7)

The style of ornament is identical to that of A. fresvillensis, and there are, according to Steinmann,
eleven umbilical tubercles and forty to forty-five ventral ribs as opposed to thirteen to fifteen
umbilical tubercles and forty-eight ventral ribs in fresvillensis. An examination of the lectotype of
fresvillensis shows identical ornament in both form and density, although the lectotype of quiriquinae
is more compressed (Wb: Wh ratio is 0.77 vs. 0-94). I regard them as conspecific.

P. supremus Petho, 1906 (p. 88, pi. 5, fig. 1) is also a macroconch fresvillensis ; it is from the
Maastrichtian of Fruska Gora, Yugoslavia. The sketchily figured Brazilian P. sumneri , P. poseidon,
and Canadoceras riogramense of Maury (1930) may belong here, but they are scarcely recognizable
from the figures; they are Maastrichtian in age. P. subrobustus (Seunes, 1 89 1 ) (p. 15, pi. 13(2), fig. 1 ) is
immediately distinguished by its evolute coiling, coarse ribs, and lack of umbilical bullae/spines.
A. wittekindi (Schliiter, 1872) (see Blaszkiewicz 1980, p. 50, pi. 42, figs. 1 and 2; pi. 43, fig. 2; pis. 44-47;
pi. 48, figs. 3 and 4; pi. 49, figs. 1 and 3; pi. 50, figs. 2 and 3; pis. 51-53) and A. vistulensis Blaszkiewicz,
1980 (p. 48, pi. 42, figs. 3 and 4; pi. 43, figs. 1 and 3; pi. 48, figs. 1 and 2) both have much more coarsely
ribbed nuclei than the present form, while P. wittekindi has a middle feebly ribbed and an adult
strongly ribbed growth stage and P. vistulensis a strongly ribbed adult stage, all features which
immediately distinguish them from the present species.

P. auritocostatus of Seunes (1890Z?, p. 239, pi. 8, fig. 4) non Schliiter, a diminutive bituberculate
form that occurs with A. fresvillensis at the Carriere des Bernes between Gan and Rebenacq in the
Pyrenees-Atlantiques, may be the microconch of this species; I have, however, failed to locate the
original specimen and can do no more than suggest the possibility.

Occurrence. Upper Maastrichtian of the Cotentin and Pyrenees-Atlantiques, France; the Maastricht area,
Holland; Denmark, Yugoslavia, Armenia, southern India, Madagascar, Western Australia, Chile, and
Brazil (?).

EXPLANATION OF PLATE 8

Figs. 13. Anapachydiscus fresvillensis (Seunes, 1890u), BMNH C524 (ex Museum of Practical Geology
Collections), ‘Inf. Oolite’, but from Upper Maastrichtian Calcaire a Baculites of Cotentin Peninsula, Manche,
France; mentioned by Spath ( 1921, p. 265) as Parapachy discus colligatus, x 1.

PLATE 8

KENNEDY, Anapachydiscus

48

PALAEONTOLOGY, VOLUME 29

Superfamily hoplitaceae H . Douville, 1890

[nom. correct Wright and Wright 1951, p. 21, pro Hoplitida Spath, 19226, p. 95, nom. transl. ex Hoplitidae
Douville, 1890]

Family placenticeratidae Hyatt, 1900

[ = Hypengonoceratinae Chiplonkar and Ghare, 1976, p. 2; Baghiceratinae Chiplonkar and Ghare, 1976, p. 3]

Genus hoplitoplacenticeras Paulcke, 1906 (ICZN name no. 1348)

[ = Dechenoceras Kayser, 1924, p. 175]

Type species. Hoplites-Placenticeras plasticus Paulcke, 1906, p. 186: ICZN Opinion 554, 1959: name no. 1629.
Discussion. See Kennedy and Wright (1983, p. 870) for diagnosis and occurrence of this genus.

Hoplitoplacenticeras lasfresnayanum (d'Orbigny, 1841 )

Plate 9, figs. 4 6; text-fig. 10b

1841 Ammonites lasfresnayanus d’Orbigny, p. 326, pi. 97, figs. 3-5.

1850 Ammonites lasfresnayanus d’Orbigny, p. 212.

1894 Hoplites lasfresnayi d’Orbigny sp.; de Grossouvre, p. 121, pi. 23, fig. 4.

1925 Hoplites Lasfresnayanus d'Orbigny; Diener, p. 176.

1965 Hoplitoplacenticeras lasfresnayanum (d’Orbigny); Howarth, p. 391 .

Holotype. By monotypy, SP unreg., the original of d’Orbigny (1841, p. 326, pi. 97, figs. 3-5), from Fresville.

Dimensions

D Wb Wh Wb.Wh U

Holotype c 42-4(100) 14-6(34-4) 19 2(45-3) 0-76 10-0(23-6)

Description. The holotype and only known specimen is an internal mould with half a whorl of body-chamber.
Coiling moderately involute on inner whorls, becoming more evolute on last half whorl, suggesting maturity.
Umbilicus small (23-6% of diameter at maximum) and shallow, with flattened, outwards-sloping wall.

Umbilical shoulder sharply and narrowly rounded. Whorl section compressed with greatest breadth at
umbilical shoulder; whorl breadth to height ratio 0-76. Inner flanks rounded; outer flanks flattened, converging
to narrow venter that is flattened intercostally with narrowly rounded ventrolateral shoulders.

Sixteen small, sharp umbilical bullae on outer whorl. On phragmocone and early body-chamber these give rise
to broad, flat-topped, rapidly expanding, flexuous, prorsiradiate primary ribs, each of which is separated by a
narrow, deep interspace from a similarly broad and flat-topped secondary rib, inserted well below mid-flank.
Each rib terminates in small outer ventrolateral clavus, while corresponding if small ventral clavus is also present
(PI. 9, fig. 6). Venter between smooth and sulcate with clavi on opposite sides slightly offset to opposite but not
alternate.

explanation of plate 9

Figs. 1-3. Anapachydiscus fresvi/lensis (Seunes, 1890a), BMNH C524 (ex Museum of Practical Geology
Collections), inner whorls, ‘Inf. Oolite’, but from Upper Maastrichtian Calcaire a Baculites of the Cotentin
Peninsula.

Figs. 4-6. Hoplitoplacenticeras lasfresnayanum (d’Orbigny, 1841), SP unreg., holotype, from Fresville.

Fig. 7. Pachydiscus ( Pachydiscus ) jacquoti Seunes, 1890a, EMP unreg., syntype, from Fresville; original of
Seunes (1890a, pi. 3 (2), fig. 3).

Figs. 8-10. Diplomoceras cylindraceum (Defrance, 1816), MNHP d’Orbigny Collection no. 7203, from Ste
Colombe.

All from Upper Maastrichtian Calcaire a Baculites of Manche, France. All x 1.

PLATE 9

KENNEDY, Anapachy discus, Hoplitoplacenticeras, Pachydiscus (Pachydiscus).

Diplomoceras

50

PALAEONTOLOGY, VOLUME 29

Ribbing irregular on last quarter whorl of body-chamber, with irregular non-bullate primaries and
intercalated secondaries. Ventrolateral and ventral clavi have merged into a single clavus and there is irregular
spacing and development of this tubercle suggesting minor pathological disturbance of ornament.

Suture incompletely exposed (text-fig. 10b) with moderately subdivided lobes and saddles; L asymmetrically
bifid to subtrifid; L/U2 asymmetrically bifid, U2 small.

Discussion. Ammonites lasfresnayanus is referred to Hoplitoplacenticeras on the basis of the ribbing
and presence of outer ventrolateral and ventral tubercles, which recall in several respects the style
seen in the type species, H. plasticum Paulcke, 1906. It differs from all other Hoplitoplacenticeras in
the very simple suture, without the multiplication of adventive and auxiliary elements so typical of the
main stream of the genus. In terms of ornament it is closest to H. marroti (Coquand, 1859) (de
Grossouvre 1 894, p. 1 1 8, pi. 8, fig. 3; pi. 9, figs. 2 and 3) which has more numerous, narrower, rounded
rather than flattened ribs and stronger tubercles, and H. dolbergensis (Schliiter, 1876) (p. 159, pi. 44,
figs. 1-4) which has rather similar (if coarser) tubercles but ribs that loop between umbilical bullae
and inner ventrolateral clavi (see also Giers 1964, pi. 6, figs. 2-7).

The suture line is not typical of Hoplitoplacenticeras nor of the Placenticeratidae as a whole;
its simplicity recalls that of ancestral Hoplitidae. This apart, I see no reason for not referring
it to Hoplitoplacenticeras , which is otherwise restricted to the Upper Campanian (fide Howarth
1965).

Occurrence. As for holotype.

Suborder ancyloceratina Wiedmann, 1966
Superfamily turrilitaceae Gill, 1871
[ = Diplomocerataceae Brunnschweiler, 1966, p. 14]

Family diplomoceratidae Spath, 1926
[ = Neocrioceratinae Spath, 1953, p. I 7]

Subfamily diplomoceratinae Spath, 1926
[ = Scalaritinae Ward, 1976, p. 455]

Genus glyptoxoceras Spath, 1925
[ = Neohamites Brunnschweiler, 1966, p. 48]

Type species. Hamites rugatus Forbes, 1846a, p. 117, by original designation.

Glyptoxoceras sp.

Material. FSR unreg., from Orglandes.

Description. The specimen is a fragment only, 14-5 mm long with maximum whorl height of 5 mm. Whorl section
compressed oval (Wb:Wh = 0-8) with rib index 3 0-3-5. Ribs coarse and distant, strongly prorsiradiate on
flanks, passing straight across venter but flexed forwards and convex on dorsum.

Sutures not seen.

Discussion. This enigmatic, straight, coarsely ribbed fragment is referred to Glyptoxoceras by
comparison with coarse-ribbed species such as G. largesulcatum (Forbes, 1846a). It could
conceivably be a Phylloptychoceras Spath, 1953, but those specimens of this genus I have studied are
ornamented by broad bulges rather than the clearly differentiated ribs of the present form.
Glyptoxoceras species occur in the Upper Maastrichtian of Kunraed in the Maastricht area, and the
present occurrence is not unexpected.

Occurrence. As for material.

KENNEDY: UPPER MAASTRICHT! AN AMMONITES

51

Genus diplomoceras Hyatt, 1900
[ = Eudiplomoceras Brunnschweiler, 1966, p. 18]

Type species. Baculites cylindracea Defrance, 1816, p. 160, by original designation.

Occurrence. Maastrichtian of western and central Europe, the transcaucasian region of the USSR, Greenland,
Zululand, Madagascar, southern India, Japan, Alaska, British Columbia, California, Antarctica, South
America, New Zealand, and Australia.

Diplomoceras cylindraceum (Defrance, 1816)

Plate 4, figs. 1 and 2; Plate 9, figs. 8-10; Plate 10; text-figs. 3i l, 6, 7g-m

1816 Baculites cylindracea Defrance, p. 160.

1817 Baculites gigantea Desmarest, p. 47, pi. 1, figs. 1 and 2.

1825-1827 Hamites cylindricus Blainville, p. 382, pi. 23, fig. 1.

1842 Hamites cylindraceus D’Orbigny, p. 551, pi. 136, figs. 1-4.

718466 Hamites elatior Forbes in Darwin, p. 265.

1847 Hamites hampeanus Hauer, p. 75.

1851 1856 Hamites . . . Woodward, p. 65, fig. 58.

1858 Hamites cylindraceus Defr. sp.; Hauer, p. 8, pi. 1 (2), figs. 3-6.

1861 Hamites cylindraceus , d’Orbigny; Binkhorst, p. 36, pi. 5b, figs. 5-7 (with additional early
synonymy).

1869 Hamites cylindraceus , Defrance, sp.; Favre, p. 26, pi. 7, fig. 1.

1872 Hamites cf. cylindraceus Defr. sp.; Schliiter, p. 103, pi. 31, figs. 10-14; pi. 29, figs. 8 and 9.

1873 Hamites cyindraceus Defr. sp.; Redtenbacher, p. 130.

71890 Hamites elatior Forbes?, White, p. 13, pi. 2, figs. 1 and 2.

1891 Hamites cylindraceus Defr. sp.; Bohm, p. 51.

71895 Hamites ( Anisoceras ) indicus Forbes; Kossmat, p. 129 (33) (pars), pi. 19 (5), fig. 8 only.

1898 Pachydiscus sp. Mariani, p. 56 (6), pi. 8 ( 1 ), fig. 5.

1898 Hamites cf. cylindraceus Defr. sp.; Mariani, p. 57.

71901 Hamites aff. cylindraceus Defrance sp.; Imkeller, p. 53.

1902 Hamites cylindraceus Defrance; Ravn, p. 249.

1903 Hamites elatior Forbes; Weller, p. 418, pi. 2, fig. 3.

1903 Hamites sp. Weller, p. 418, pi. 2, fig. 4.

1903 Diplomoceras notabile Whiteaves, p. 335, pi. 44, fig. 4.

1909 Anisoceras notabile Whiteaves; Kilian and Reboul, p. 15 (pars.), pis. 2 and 3; ?pl. 4; ?pl. 6, fig. I .
1913 Hamites cylindraceus Defrance sp.; Nowak, p. 382, pi. 41, fig. 10; pi. 43, fig. 35; pi. 45, fig. 47.
71930 Glyptoxoceras parahybense Maury, p. 185, pi. 11, fig. 2.

1938 Diplomoceras cylindraceum Defrance; Collignon, p. 56.

1951 Diplomoceras cf. cylindraceum (Defrance); Mikhailov, p. 41, pi. 2, figs. 9 and 10; text-fig. 10.

195 1 Diplomoceras cylindraceum Defr. var. Ivovensis var. nov., Mikhailov, p. 42, pi. 2, figs. 7 and 8; text-
fig. 1 la, b.

1952 Diplomoceras notabile Whiteaves, 1903; Usher, p. 109, pi. 29, fig. 2; pi. 30, fig. 1; pi. 31, figs. 26
and 27.

1953 Hamites cylindraceus Defrance; Petkovic, p. 33, pi. 6, figs. 1, 4-6.

1953 Diplomoceras Iambi Spath, p. 17, pi. 2, figs. 1 -3; pi. 3, fig. 1.

1953 Diplomoceras cylindraceum (Defrance in d’Orbigny); Spath, p. 17.

1953 Diplomoceras notabile Whiteaves; Spath, p. 17, pi. 2, fig. 4.

71958 Diplomoceras jimboi Anderson, p. 199, pi. 68, fig. 5.

71958 Diplomoceras oshaughnessyi Anderson, p. 201, pi. 56, fig. 2.

1959 Diplomoceras cylindraceum (Defrance); Naidin and Shimanskij, p. 181, pi. 3, fig. 2.

1962 Diplomoceras (Diplomoceras) cf. notabile Whiteaves; Wiedmann, p. 208.

1963 Diplomoceras notabile Whiteaves; Jones, p. 32, pi. 21, fig. I; text-fig. 15.

1964 Diplomoceras cylindraceum (Defrance); Tsankov, p. 152, pi. 4, fig. 2.

71965 Diplomoceras sp. Birkelund, p. 67, pi. 16, figs. 1 and 2.

1966 Eudiplomoceras raggati Brunnschweiler, p. 18, pi. 8, fig. 7; text-figs. 4 and 5.

1966 Diplomoceras cf. notabile (Whiteaves, 1903); Brunnschweiler, p. 20, pi. 7, fig. 3; text-fig. 6.

52

PALAEONTOLOGY, VOLUME 29

1966 Diplomoceras notabile (Whiteaves, 1903); Brunnschweiller, text-fig. 7.

71970 Diplomoceras sp. Henderson, p. 27, pi. 3, fig. 5.

1971 Diplomoceras notabile Whiteaves; Collignon, p. 11, pi. 644, figs. 2377-2379.

1976 Diplomoceras Iambi Spath; Del Valle and Rinaldi, p. 1, pis. 110.

1976 Diplomoceras cylindraceum Defrance; Klinger, p. 81 et seq.

1976 Diplomoceras gr. ex. Iambi Spath; Klinger, p. 82.

1976 Diplomoceras gr. ex. cylindraceum Defrance; Klinger, p. 82.

1976 Diplomoceras ( Diplomoceras ) notabile Whiteaves, 1903; Klinger, p. 82, pi. 34, figs. 2 and 4.

1979 Diplomoceras cylindraceum (Defrance, 1816); Birkelund, p. 55.

1980 Diplomoceras cylindraceum Ivovensis Michailov, 1951; Blaszkiewicz, p. 30, pi. 54, fig. 4.

1980 Diplomoceras cylindraceum cylindraceum (Defrance, 1916 [.v/c]); Blaszkiewicz, p. 30, pi. 54, fig. 2;
pi. 55, figs. 6 and 7.

1982 Diplomocers cylindraceum (Defrance, 1822); Tsankov, p. 22, pi. 6, figs. 1-3.

71982 Diplomoceras notabilel Whiteaves; Martinez, p. 168, pi. 29, fig. 6.

Type. Defrance (1816, p. 160) described the species as follows: ‘Cette especeest cylindrique. Ses cloisons sont tres
profondement decoupees. Son test est sillonne transversalement, et Ton voit a l’exterieur une trace longitudinale
qui est sans doute celle du siphon. Le plus grand morceau de cette espece que j’ai vu, a dix-neuf decimetres (sept
pouces) de longuer, sur quarante millimetres (dix-huit lignes) de diametre a sa base, et il est tronque par le deux
bouts. Elle se trouve avec la precedent; mais elle est beaucoup plus rare.’

‘La precedent’ is 'La Baculite vertebrate, foss. de Maastricht’. This is a perfectly valid diagnosis and the species
dates from Defrance, rather than d’Orbigny (1842) as some authors suggest. It is also clear that the locality
Maastricht is given for the species. Defrance's specimens, or those he studied, have not been traced. A neotype
will be designated in my revision of the type Maastrichtian (in prep.).

Material. BMNH C6410b (the original of Woodward 1851-1856, p. 96, fig. 58; p. 210, fig. 65), BMNH C37027
(ex Tesson Collection, mentioned by Spath 1953, p. 17), both from Fresville; BMNH 48763, without precise
locality data, C70643 and C70644 (ex J. Sowerby, ex de Gerville Collection) from Valognes; MHNG, six
unregistered specimens from Valognes; NHMW 7479 from Orglandes; FSR 4-6 from Ste Colombe; EMP
unreg., unlocalized (two specimens); MNHP R1204 (ex de Vibraye Collection, 1896 1927) from Valognes,
R1203 from Golleville, R1206 from Fresville; MNHP d’Orbigny Collection 7203 from Ste Colombe.

Wb

Wh

Wb: Wh

BMNH 48763

19 9

2L9

0 91

23-5

26-2

0-90

NHMW 7479

22-3

25-0

0-89

MHNG unreg.

23-1

25-9

0-89

BMNH 37027

28-2

30-7

0-92

35-0

38-5

0 91

MHNG unreg.

28-8

290

0-99

33-5

36-5

0-92

MHNG unreg.

47-0

48-5

0-97

FSR 5

42-5

440

0-97

FSR 6

42-5

44-5

0-96

FSR 4

510

52-0

0-98

Description. All material is in form of septate internal moulds; a few have traces of external ornament and there is
a single external mould. The material consists of fragments of straight, slowly expanding shafts and associated

EXPLANATION OF PLATE 10

Figs. 1-4. Diplomoceras cylindraceum (Defrance, 1816), from Upper Maastrichtian Calcaire a Baculites of
Fresville, Manche, France. I and 2, BMNH 6410b; original of Woodward (1851-1856, p. 96, fig. 58; p. 201,
fig. 65) and mentioned by Spath (1953, p. 17). 3 and 4, BMNH 37027 (ex Tesson Collection); mentioned by
Spath ( 1953, p. 17).

All x 1.

PLATE 10

*J1

0*7 • ■ • Pi •

KENNEDY, Diplomoceras

54

PALAEONTOLOGY, VOLUME 29

text-fig. 6. Diplomoceras cylindraceum (Defrance, 1816). a-c, BMNH 48763 (ex Bright Collection),
by its preservation, from Upper Maastrichtian Calcaire a Baculites of theCotentin Peninsula, Manche,
France; specimen shows particularly strong ornament for internal mould of this species, d, e, BMNH
C376, silicone squeeze taken from external mould, showing external ornament of part of two limbs of
the same specimen; compare with text-fig. 8. All figures natural size.

KENNEDY: UPPER MAASTRICHT! AN AMMONITES

55

curved portions that show shell to have consisted of at least two subparallel shafts, possibly three. Smallest
specimen has whorl height of 21 -9 mm and is part of curved portion; largest, straight portion has whorl height
of 51 mm.

As can be seen from table of dimensions, whorl section varies from compressed to near equidimensional, with
whorl breadth to height ratio of 0-89 to 0-99. Sections vary from oval with venter only slightly narrower
than dorsum to distinctly ovoid/rounded subtrigonal to nearly circular. Internal moulds vary from virtually
smooth (PI. 4, figs. 1 and 2; PI. 9, figs. 8 10) to faintly (PI. 10, figs. 3 and 4) to distinctly (if subduedly) ribbed (text-
fig. 6a-c). Rib direction on straight portions varies from almost rectiradiate (PI. 10, figs. 3 and 4) to markedly
prorsiradiate (text-fig. 6a-c) even on same specimen (text-fig. 6d, e). It varies from prorsiradiate to rectiradiate
around hooks.

Where external ornament is preserved, ribs are annular, narrow, sharp, and separated by much wider
interspaces (text-fig. 6d, e; PI. 10, fig. 3); rib index varies from 1 1 to 13 on one specimen and between the three
specimens where ornament was visible. Occasional feeble grooves on moulds appear to be strengthened
interspaces or incipient constrictions. There are also distinct rugations on surface corresponding to apertural end
of sutures in some specimens.

Suture line is deeply and intricately subdivided (text-fig. 7g-m).

Discussion. As described here, the Calcaire a Baculites material is characterized by a variable but
never depressed ovoid/rounded to subtrigonal to nearly circular whorl section and a rib index of 1 1 to
13 on the three specimens where this was measurable. D. cylindraceum Ivovense Mikhailov, 1951
(p. 42, pi. 2, figs. 7 and 8; text-fig. 1 la, b ), the holotype of which is the original of Nowak ( 1913, p. 382,
pi. 41, fig. 10) co-occurs with such forms in several parts of Europe, and is here regarded as a
synonym. Mikhailov’s figure ( 1951 , text-fig. 1 la, b ) shows a distinctly compressed, ovoid section, but
this is due to post-mortem deformation. The rib index (16-17) is higher than the material described
here but the Cotentin sample is so small that this is not considered significant.

I can see even less difference between D. cylindraceum and the Antarctic D. Iambi Spath, 1953
(p. 17, pi. 2, figs. 1-3). Spath differentiated them (so far as one can judge) on whorl section,
compressed in cylindraceum and circular in Iambi , and details of suture. On examining the BMNH
type series, moulds of phragmocones are smooth to faintly ribbed, but moulds of body-chambers
bear strong ribs. The rib direction varies as in the French material. The whorl breadth to height ratio
of eight uncrushed specimens varied from 0-95 to 1-06, with five specimens slightly compressed and
four slightly depressed. The rib index, measurable on only three specimens, was 13, 14, and 17.
D. notabile Whiteaves, 1903 (p. 335, pi. 44, fig. 4; holotype refigured by Usher 1952, pi. 29, fig. 2) has,
according to Whiteaves, a whorl breadth to height ratio of 0-8 at a whorl height of 47 mm and 0-84 at
55 mm, thus being more compressed than any of the present specimens, and with a slightly higher rib
density. BMNH C3486 and C41424 had whorl breadth to height ratios of 0-87 and 0-90 and rib
indices of 14 and 12 respectively. Alaskan examples (Jones 1963, p. 32, pi. 21, fig. 1) have whorl
breadth to height ratios of 0-80 to 0-89 and rib indices of 1 1 or 12. Usher was impressed by the sutural
differences between D. cylindraceum , as illustrated by d’Orbigny, and D. notabile , pointing to the
greater degree of incision in the Canadian form, especially the degree of incision of the external
saddle. It is, at most, subspecifically distinct. Hamites elatior Forbes, 18466 is based on an inadequate
description, the types being lost. H. hampeanus Hauer, 1847 is a clear synonym, as Hauer pointed out
in 1858 (p. 8, pi. 1, figs. 3-6). The H. elatior of White (1890, p. 1 3, pi. 2, figs. 1 and 2) has a compressed,
parallel-sided whorl section and a rib index of 20, but White states it to be crushed. It resembles the
finely ribbed specimens of Kilian and Reboul (1909, pi. 4) and Weller (1903). Eudiplomoceras raggati
Brunnschweiler, 1966 (p. 18, pi. 8, fig. 7; text-figs. 4 and 5) is a further synonym. The inadequately
described D. jimboi and D. oshaugnessyi of Anderson (1958) are doubtfully referred to the present
species. D. australe Hunicken, 1965 (p. 67, pi. 4, figs. 1 -4) has a whorl breadth to height ratio of up to
1 -6 and seems distinct enough on this criterion.

Occurrence. This species ranges throughout most of the Maastrichtian. The precise Danish records of Birkelund
(1979, text-fig. 1 ) show it first appearing low in the Belemnella lanceolata Zone and extending to the top of the B.
casimirovensis Zone. It has a world-wide distribution, with records from north-west France, northern Spain (?),
Italy, Holland, Denmark, north Germany, Poland, Austria, the USSR, southern India (?), Zululand,

56

PALAEONTOLOGY, VOLUME 29

text-fig. 7. Sutures, a-c, Baculites anceps Lamarck, 1822, all MHNG unreg. (Pictet Collection), d-f, B.
vertebralis Lamarck, 1801: d, BMNH C70592; E, MHNG unreg. (Pictet Collection); F, NHMW 7460. g-m,
Diplomoceras cylindraceum (Delrance, 1816): G-i, MHNG unreg. (Pictet Collection); j, K, BMNH 37027; M,

NHMW 7479.

KENNEDY: UPPER MAASTRICHT! AN AMMONITES

57

Madagascar, Australia, New Zealand (?), the Antarctic, South America, California, British Columbia, Alaska,
and Greenland (?).

Family baculitidae Gill, 1871
[ = Eubaculitinae Brunnschweiler. 1966, p. 4]

Genus baculites Lamarck, 1799

[ = Homaloceratites Hupsch, 1768, p. 110 (non binomen ); Euhomaloceras Spath, 1926, p. 80]

Type species. Baculites vertebralis Lamarck, 1801, p. 103, by subsequent designation of Meek (1876, p. 391 ).
Discussion. See Kennedy ( 1984c/) for recent diagnosis and discussion of the genus.

1742
1768
1799
1801
1817
1822
non 1825
non 1828
71850
1861
1876

71901

1902

1907

1908
1925
1951

non 1964
1965
1979

Baculites vertebralis Lamarck, 1801
Plate 1 1, figs. 6-11; Plate 12, figs. 1-6; text-figs. 3a-d, 7d-f, 8

Spendylolitte Bourguet, p. 74, pi. 49, figs. 313-316.

Homaloceratites Hupsch, p. 1 10, pi. 4, figs. 11, 15, 18, 19 (non binomen).

Corne d’ammon droite . . . Faujas-Saint-Fond, p. 140, pi. 21, figs. 2 and 3.

Baculites vertebralis Lamarck, p. 103.

Baculites vertebralis Lamarck; Desmarest, p. 49, pi. 2, figs. 7 and 8.

Baculites Faujasii Lamarck, p. 647.

Baculites vertebralis Lamarck; Blainville, p. 380, pi. 12, figs. 1-3.

Baculites faujasii J. de C. Sowerby, p. 186, pi. 592, fig. 1.

Baculites Faujasii Lamarck; Alth, p. 208, pi. 10, figs. 33-36.

Baculites faujasi, Lamarck; Binkhorst, p. 40, pi. 5c/, fig. 1 (with extensive synonymy).

Baculites vertebralis Lam.; Schliiter, p. 143 (pars), pi. 39, figs. 12 and 13, non fig. 11; pi. 40, figs. 4
and 5, non fig. 6.

Baculites vertebralis Lam. (Schliiter); Imkeller, p. 54.

Baculites vertebralis Lamarck; Ravn, p. 250.

Baculites vertebralis Lamarck; Pervinquiere, p. 92 (pars), non pi. 4, fig. 9.

Baculites vertebralis Lamarck; Nowak, p. 346, pi. 14, fig. 8.

Baculites vertebralis Lamarck; Diener, p. 64 (pars) (with synonymy).

Baculites vertebralis Lamarck; Mikhailov, p. 48, pi. 1, figs. 4-6.

Baculites vertebralis Lam.; Giers, p. 256, text-figs. I and 2.

Baculites vertebralis Lamarck; Howarth, pp. 363 and 368.

Baculites vertebralis Lamarck, 1801; Birkelund, p. 53.

Types. B. vertebralis was introduced by Lamarck in 1801 without description, but with reference to the figures of
Faujas-Saint-Fond (1799, p. 141, pi. 21, figs. 2 and 3) and Bourguet (1742, pi. 49, figs. 313-316). The original of
Faujas-Saint-Fond’s pi. 21, figs. 2 and 3, is herein designated lectotype of the species. It is the holotype, by
monotypy, of B. faujasi Lamarck, 1822 (p. 647).

Material. BMNH C70591-C70593 from Valognes (ex J. Sowerby, ex de Gerville Collection); NHMW 7460
from Fresville (7 ex de Gerville Collection); MNHG, three unregistered specimens (ex Pictet Collection).

Wb

Wh

Wb : Wh

MHNG unreg.

21-0

37-0

0-57

NHMW 7460

17-0

32-0

0-53

131

23-8

0-55

BMNH C70593

14-3

23-9

0-60

BMNH C70592

12-4

21-3

0-58

Description. All specimens are internal moulds. Medium-sized for genus, straight, slowly expanding,
compressed, with whorl breadth to height ratio varying between 0 53 and 0-60. Whorl section oval with dorsum
more broadly rounded than venter and sides markedly flattened. Five specimens studied are almost smooth

58

PALAEONTOLOGY, VOLUME 29

(text-fig. 8a-e) or ornamented by growth striae and feeble riblets (PI. 1 1, fig. 7; PI. 12, figs. 2 and 5). These
are feebly convex and transverse on dorsum, sweep back into a marked concavity on dorsolateral area,
and are projected strongly forwards on ventrolateral area, meeting line of venter at 30° and crossing
venter in narrow convexity. These specimens show feeble longitudinal groove corresponding to position of
umbilical lobe.

Two MHNG specimens show much stronger ornament (PI. 11, figs. 9 11), with growth striae and riblets
strengthened into concave, crescentic dorsolateral rib. In best-preserved specimen (PI. 1 1, figs. 9-11) these are
disturbed by series of pathological excrescences, but a rather worn specimen (not figured) shows 3 0-3-5 such
ribs in a distance equal to whorl height. Irregular constrictions sometimes developed.

Suture (text-fig. 7d-f) relatively complex for genus, with deeply incised bifid elements. E/L and L/U tall, L
narrow, U relatively broad, U/I squat.

Discussion. B. vertebralis is immediatly distinguished from the other Calcaire a Buculites species,
B. anceps Lamarck, 1822, by the oval rather than tear-shaped cross-section, by which they can be
differentiated even as single camerae. The venter of vertebralis is rounded, that of anceps acute and
flanked by grooves (PI. 11, figs. 12 14; PI. 12, figs. 7-11), while the growth lines and riblets of anceps
intersect the line of the venter at a much smaller angle (compare PI. 12, figs. 5 and 7); anceps also has
much simpler, squat, little-incised sutural elements (compare text-fig. 7a-c and 7d-f). B. faujasi
Lamarck, 1822 (p. 647) is an objective synonym, having the same type as B. vertebralis. B. knorrianus
Desmarest, 1817 (p. 48, pi. 1, fig. 3) is a further species commonly recorded from the European
Maastrichtian (synonymy in Diener 1925, p. 61; see also Birkelund 1979). I interpret it in terms of
specimens from Nagorzany, Galicia (NHMW 7459u-c and BMNH 74030«-t/). This is a very large
species, with a whorl height of up to 80 mm in specimens I have seen. The whorl section is ovoid, with
a broadly rounded venter (as in B. vertebralis ) but with strongly convergent flanks and a narrower
venter. Ornament is weak to obsolete in most specimens, but some show distinct to strong ventral
ribbing and others ribs that extend on to the ventrolateral region. The suture is even more deeply and
intricately subdivided than in B. vertebralis.

Although only a handful of B. vertebralis are known from the Calcaire a Baculites , it is of interest
to note that individuals are mature at disparate sizes: BMNH C70592 (PI. 12, figs. 1-3)
shows approximated sutures at a whorl height of 19-5 mm whereas one of the MHNG specimens
(PI. 1 1, figs. 6-8) is still septate at a whorl height of 38-0 mm. The sample is, of course, too small to do
anything but suggest the possibility of size dimorphism.

Occurrence. Calcaire a Baculites , Upper Maastrichtian of Valognes and Fresville, Manche, France. The type
material is from the Upper Maastrichtian of St Pietersberg, Maastricht, where it is relatively common. It also
occurs at localities such as Kunraed and elsewhere in Limburg and Hainault, in the Upper Maastrichtian of the
Petites Pyrenees (Haute Garonne), in Denmark, southern Sweden, north Germany, Poland, the southern USSR,
and Tunisia.

Baculites anceps Lamarck, 1822

Plate 1 1 , figs. 12-14; Plate 1 2, figs. 7-11; text-figs. 3e-h, 7a-c

1822 Baculites anceps Lamarck, p. 648.

1885 Baculites schliiteril Moberg, p. 40, pi. 4, fig. 13 only.

EXPLANATION OF PLATE 11

Figs. 1 -5. Pachydiscus ( Pachydiscus ) gollevi/lensis (d’Orbigny, 1850). 1 , 4, 5, SP unreg., from Golleville; inner
whorls of original of Seunes (1891, pi. 14 (5), fig. 3). 2 and 3, MHNG unreg. (Pictet Collection), from
Valognes.

Figs. 6-11. Baculites vertebralis Lamarck, 1801. 6-8, 9-11, MHNG unreg. (Pictet Collection), from Valognes.
Figs. 12-14. B. anceps Lamarck, 1822, MHNG unreg. (Pictet Collection), from Valognes.

All from Upper Maastrichtian Calcaire a Baculites of Manche, France. All x 1 .

PLATE 11

KENNEDY, Pachydiscus (P achy discus), Baculites

60

PALAEONTOLOGY, VOLUME 29

text-fig. 8. Baculites vertebralis Lamarck, 1801, from Upper Maastrichtian Calcaire a Baculites of Manche,
France, a, b, NHMW 7460 from Fresville; c-e, BMNH C70591 (ex J. Sowerby, exde Gerville Collection) from

Valognes; all figures natural size.

KENNEDY: UPPER MAASTRICHT! AN AMMONITES

61

non 1963 Baculites cfr. anceps Lamarck, 1799; Young, p. 42, pi. 2, figs. 18, 20-22.
non 1964 Baculites anceps (Lam.) emend. Nowak; Giers, p. 257, text-fig. 3.

1965 Baculites anceps Lamarck; Howarth, p. 363, pi. 4, fig. 4; pi. 5, figs. 4 and 5; pi. 6, figs. 1 -5; text-figs.
2, 3, 5 12 (with synonymy).

non 1976 Baculites anceps Atabekian and Khakhimov, p. 94, pi. 2, figs. 3 and 4; pi. 11, figs. 8-10.

1979 Baculites valognensis Boehm, 1891; Birkelund, p. 53.

71982 Baculites anceps Lamarck; Martinez, p. 169, pi. 30, figs. 1 and 2.

Type. Neotype, designated by Howarth (1965, p. 365), is BMNH 32573 from ‘Normandy’ (e.v Mantell
Collection).

Material. The several hundred specimens in the repositories listed on p. 27 are not noted separately here.
Localities given are ‘Normandy’, ‘Manche’, Fresville, Valognes, Ste Colombe, Picauville, Orglandes, Port
Filiolet, Nehou, Bonneville, and Golleville.

Discussion. Howarth (1965) has provided a full and comprehensive description and discussion of
B. anceps , to which the reader is referred. The characteristic features of the species are the tear-shaped
whorl section (text-fig. 3e-h), the acute, sharp venter flanked by grooves (PI. 1 1, fig. 12; PI. 12, figs. 8
and 11), plus strongly projected ventrolateral ribbing such that the aperture possessed a very long
rostrum. As with the material studied by Howarth, an examination of hundreds of specimens at all
growth stages shows a predominance of feebly ornamented to near smooth individuals, some with
lateral grooves, and a paucity of ribbed forms (Howarth 1965, pi. 6, fig. 1 ). Because there are so few
examples with phragmocone and body-chamber associated it is difficult to assess the state of maturity
of most specimens, but body-chambers reach a much larger size than those illustrated by Howarth;
Plate 12, figs. 7 and 8 show the largest body-chamber seen which is incomplete at a whorl height of
34 mm. 1 would also note the marked curvature of some specimens (PI. 1 1, fig. 13).

B. carinatus Binkhorst, 1861 (p. 43, pi. 5c/, fig. 2) (not Morton) from Mont St Pierre, Maastricht, is
an Upper Maastrichtian form with a curious, tear-shaped section and ventral ribs only. I was unable
to find the holotype in the Binkhorst Collection during a visit to the Museum fur Naturkunde, East
Berlin, in December 1983. B. valognensis J. Bohm, 1891 (p. 50, pi. 1, fig. 13) is based on a fragment
only from Siegsdorf, Oberbayern, and is best regarded as a nomen dubium. The specimens from the
Calcaire a Baculites named B. anceps valognensis by Nowak (1908, p. 335, pi. 14, figs. 6 and 7; text-
figs. 1 -4 on p. 33 1 and 6, 7, 9, 12 on p.337) are within the limits of this species, as Howarth noted. B. a.
leopoliensis Nowak, 1908 (p. 328, pi. 14, figs. 1-5, 10, 1 1 ) is a much larger species with strong
crescentic ribs on the flanks and persistent secondary ribs on the venter.

Occurrence. The careful records of Birkelund (1979, p. 53, as B. valognensis) show this species to be restricted to
the Upper Maastrichtian in Denmark. In Limburg it occurs as a rarity in the Upper Maastrichtian of Kunraed,
Geulhem, and at Maastricht. There are records from the Maastrichtian of the USSR and possibly Spain. The
many Campanian records of the species are based on poor material, probably of other species of ribbed
Baculites.

Genus fresvillia gen. nov.

Type species. F. constricta gen. et. sp. nov. Upper Maastrichtian, Fresville, Manche, France.

Diagnosis. Baculitids with circular whorl section ornamented by strongly prorsiradiate growth striae
and feeble riblets, periodically accentuated on the dorsolateral area into crescentic, concave ribs;
strongly projected on lateroventral area where they may branch, and crossing venter in broad
convexity; only slightly less strongly projected on dorsolateral area, crossing dorsum more or less
transversely; interrupted by close or distant constrictions, best developed on venter. Suture
moderately subdivided with triangular elements.

Discussion. The circular whorl section and periodic constrictions recall Lechites Nowak, 1908, of
which the present form is a heterochronous homoeomorph. The two differ in that the growth lines
are markedly prorsiradiate in Fresvillia , are markedly concave on the inner flank and accentuated
into periodic crescentic ribs, whilst the riblets and striae branch over the venter. Lechites are much

62

PALAEONTOLOGY, VOLUME 29

more prominently ribbed, while the constrictions are well developed on flanks, dorsum, and venter.
Direction of growth lines, style of ribs, and limitation of constrictions to the ventral region separate
the new genus from Sciponoceras Hyatt, 1894.

A number of diplomoceratids have straight limbs to the shell and a circular section; these are
Polyptychoceras Yabe, 1927, Subptychoceras Shimizu, 1935, and Phylloptychoceras Spath, 1953. All
have ribs that are only feebly prorsiradiate, deep constrictions on the flanks, and simplified sutures.
Astreptoceras Henderson, 1970 is a baculitid homoeomorph that also has only feebly prorsiradiate
growth lines and ribs as well as annular constrictions.

The present form is referred to Baculitidae rather than Diplomoceratinae because of the typically
baculitid form of the growth lines and its suture, which closely resembles that of baculitids and is not
simplified as in Polyptychoceras and its allies. F. constricta sp. nov., although known from but a single
specimen (which distinction it shares with several other Calcaire a Baculites ammonites) merits
recognition. The origin of the type species lies in the older B. teres Forbes, 1846c/ (p. 1 15, pi. 10,
fig. 5; Stoliczka 1866, p. 197, pi. 90, fig. 12 non 13; Matsumoto 1959, p. 163, pi. 45, figs. 5, 6 and text-
figs. 82 and 83), which is also referred to Fresvillia. This has a circular whorl section and growth lines
that are only a little less markedly prorsiradiate than the type species, differing in the closer spaced,
regular constrictions. B. lechi tides Brunnschweiler, 1966 (p. 23, pi. 1, figs. 1-3; text-fig. 8) may also
belong here.

Occurrence. Lower Maastrichtian of southern India, California, and Alaska. Upper Maastrichtian of Fresville,
Manche, France and possibly Western Australia.

Fresvillia constricta gen. et sp. nov.

Plate 14, figs. 39-42; text-fig. 10a

Holotype. IRSNB 10254 (e.x Leriche Collection, I.G. 19859) from the Upper Maastrichtian Calcaire a Baculites ,
Fresville, Manche, France.

Diagnosis. Fresvillia with distant constrictions.

Description. Holotype and only known specimen (PI. 14, figs. 39-42) an internal mould of part of the
phragmocone and body-chamber with maximum whorl height 8-5 mm and length 47 0 mm. Straight, slowly
expanding, with circular whorl section. Surface ornamented by growth striae and feeble riblets. Ornament
effaced on dorsum, flexed back and strongly concave on dorsolateral area, periodically strengthened into
crescentic ribs separated by a distance equal to three times median whorl height. Ribs and striae strongly
prorsiradiate on flank, curving back and crossing ventrolateral region and venter in broad convexity, branching
into groups of two or three with additional intercalatories of variable strength and looped over venter. Growth
striae strongly projected on dorsolateral area, passing more or less straight across dorsum. Marked distant
constrictions on ventrolateral and ventral region, effacing at mid-flank.

Suture (text-fig. 10a) with moderately subdivided bifid lobes and saddles with trigonal outline.

Discussion. F. teres, the second species referred to Fresvillia, has a similar whorl section and course
of growth lines, which are only slightly less projected. It is easily separated by its close, even
constrictions, quite different from the distant ones of F. constricta. The typically baculitid suture
distinguishes F. constricta from fragments of the superficially homoeomorphous smoothing

EXPLANATION OF PLATE 12

Figs. 1-6. Baculites vertebralis Lamarck, 1801. I -3, BMNH C70592 (c.vJ. Sowerby, ex de Gerville Collection).

4-6, BMNH C70593 (ex J. Sowerby, ex de Gerville Collection).

Figs. 7-1 1. B. anceps Lamarck, 1822. 7 and 8, NHMW 7482. 9-1 1, MHNG unreg. (Pictet Collection).

All from Upper Maastrichtian Calcaire a Baculites of Valognes, Manche, France. All x 1.

PLATE 12

KENNEDY, Baculites

64

PALAEONTOLOGY, VOLUME 29

diplomoceratids such as Polyptychoceras , Phylloptychoceras, Astreptoceras, and their allies, while
cross-section, form of ribs, and constrictions separate it from all contemporaneous baculitids.
Differences from the Albian-Cenomanian Lechites and Cenomanian-Turonian Sciponoceras are
noted under the generic discussion.

Occurrence. As for type.

Superfamily scaphitaceae Gill, 1871
[nom. transl. Wright and Wright 1951, p. 13 ex Scaphitidae Gill]

Family scaphitidae Gill, 1871
Subfamily scaphitinae Gill, 1871
[nom. transl. Wright 1953, p. 473 ex Scaphitidae Gill]

Genus hoploscaphites Nowak, 1911
[ = Mesoscaphites Atabekjan, 1979, p. 523 {nom. nud.)\

Type species. Ammonites constrictus J. Sowerby, 1817. p. 189, pi. A, fig. 1, by original designation.

Diagnosis. See Birkelund (1965, p. 102).

Discussion. Early Hoploscaphites are distinct enough, but some of the later forms converge with some
Scaphites Parkinson, 1811.

Occurrence. Upper Campanian to Upper Maastrichtian. Europe, Israel, Chile, Grahamland, USA, Canada, and
Greenland.

Hoploscaphites constrictus (J . Sowerby, 1817)

Plate 13, figs. 1 13, 1 6 24; Plate 14, figs. 1 38; Plate 15; text-figs. 9, 1 1a-h

1817 Ammonites constrictus J. Sowerby, p. 189, pi. A, fig. 1.

1837 Ammonites constrictus Sow.; Pusch, p. 159, pi. 14, fig. 3.

1842 Scaphites constrictus d’Orbigny; d’Orbigny, p. 522, pi. 129, figs. 8-11.

1848 Scaphites compressus, D’Orb.; Kner, p. 10, pi. 1, fig. 4.

1850 Scaphites constrictus d’Orb.; Alth, p. 207, pi. 10, figs. 29 and 30.

1850 Scaphites constrictus d'Orb.; d'Orbigny, p. 214.

1851 Ammonites monteleonensis Leymerie, p. 198, pi. 11 (C), figs. 3 and 4.

1852 Scaphites constrictus d’Orb. var; Kner, p. 300 (8), pi. 15(1), fig. 13.

1858 Scaphites multinodosus n. sp. Hauer, p. 9, pi. 1 (2), figs. 7 and 8.

explanation of plate 13

Figs. 1-13, 16-24. Hoploscaphites constrictus (J. Sowerby, 1817). 1-3, MNB unreg. (ex de Gerville Collection),
a small macroconch, from Orglandes; original of Schliiter (1872, pi. 28, figs. 6-8) 4-9, BMNH C70645 {ex
J. Sowerby, ex de Gerville Collection), paralectotype, from [Ste Colombe] "near Orglandes’, a small
macroconch. 10 and 1 1, EMP ‘c’ (Deshayes Collection), from Orglandes. 12 and 1 3, SP 9 unlocalized juvenile
macroconch. 16 and 17, MNHP d’Orbigny Collection no. 7194, macroconch from Ste Colombe; probably
original of d’Orbigny (1842, pi. 129, figs. 8, 9, ?1 1). 18 and 19, MNHP unreg., macroconch from Cussy, near
Fresville. 20-22, BMNH C36733, lectotype, macroconch from Ste Colombe; original of James Sowerby
(1817, pi. A, fig. 1). 23 and 24, SP 10 (ex Munier-Chalmas Collection), from Valognes.

Figs. 14 and 15. Hoploscaphites sp., SP 1 3, imprecisely localized.

All from Upper Maastrichtian Calcaire a Baculites of Manche, France. All x 1.

PLATE 13

vo- •-'l

KENNEDY, Hoploscaphites

66

PALAEONTOLOGY, VOLUME 29

1861 Scaphites constrictus d’Orbigny; Binkhorst, p. 38, pi. 5 d, fig. 6 a-h (with synonymy).

1861 Scaphites multinodosus v. Hauer; Gumbel, p. 574.

1861 Scaphites (?) falcifer Guemb., Gumbel, p. 574.

1 861 Scaphites ornatus Roem.; Gumbel, p. 576.

1 869 Scaphites constrictus Sowerby, sp.; Favre, p. 18, pi. 5, figs. 1 -4.

1872 Scaphites constrictus Sow. sp.; Schliiter, p. 92, pi. 28, figs. 5-9 (with synonymy).
non 1873 Scaphites spec, indet. cfr. Scaphites constrictus Sow.; Redtenbacher, p. 130, pi. 30, fig. 12.

1885 Scaphites constrictus Sowerby sp., Moberg, p. 27, pi. 3, figs. 3-5.

1891 Scaphites constrictus Sow. sp.; Bohm, p. 48, pi. 1, fig. 10a.

1894 Scaphites constrictus Sowerby sp.; de Grossouvre, p. 248, pi. 31, figs. 1, 2, 7, 8.

1 894 Scaphites niedzwiedzkii Uhlig, p. 220, text-fig. 2.

1 899 Scaphites constrictus Sow.; Semenow, p. 1 34, pi. 5, fig. 8.

1902 Scaphites constrictus Sowerby, sp.; Ravn, p. 254, pi. 3, fig. 9.

1907 Scaphites constrictus Sow.; Wisniowski, p. 193, pi. 17, fig. 2b.

1907 Scaphites constrictus var. Niedzwiedzkii Uhl.; Wisniowski, p. 193, pi. 17, fig. 2a.

1908 Scaphites constrictus Sowerby, sp.; de Grossouvre, p. 36, pi. 11, figs. 3-7.

1909 Scaphites constrictus Sow; Nowak, p. 773, pi. 1, fig. I .

71909 Scaphites cfr. Niedzwiedzkii Uhlig; Bohm in Bohm and Heim, p. 54, pi. 1, fig. 3.

1911 Scaphites constrictus Sow.; Lopuski, pp. 1 13, 133, pi. 2, figs. 3 and 4.

1911 Scaphites constrictus Sow. var. crassus mihi; Lopuski, pp. 1 1 5, 1 34, pi. 2, figs. 5 and 6; pi. 3, figs. 1

and 2.

1911 Scaphites sp. Lopuski, p. 117, pi. 3, fig. 4.

7191 1 Scaphites sp. Lopuski, p. 118, pi. 3, fig. 3.

1911 Scaphites sp. Lopuski, p. 118, pi. 3, fig. 5.

1911 Hoploscaphites constrictus Sowerby vulgaris Nowak, p. 583, ?pl. 32, fig. 6; pi. 33, figs. 8-12.

1911 Hoploscaphites constrictus-tenuistriatus Kner; Nowak, p. 585, pi. 33, fig. 14 (non 13).

1915 Scaphites constrictus Sowerby; Freeh, p. 562 (pars), text-figs. 9 and 710.

1925 Discoscaphites constrictus Sowerby; Diener, p. 210 (with synonymy).

1932 Hoploscaphites constrictus Sowerby; Wolansky, p. 10, pi. Lfigs. 10 and 12.

1951 Discoscaphites constrictus (Sowerby); Mikhailov, p. 90, pi. 17, figs. 77-80 (with synonymy).

1951 Discoscaphites constrictus (Sow.) var. niedzwiedzkii (Uhlig); Mikhailov, p. 93, pi. 15, fig. 65; pi. 1 7,
figs. 81 and 82; pi. 18, fig. 85.

1959 Discoscaphites constrictus (Sowerby); Naidin and Shimanskij, p. 196, pi. 6, figs. 7 and 8.

1959 Discoscaphites constrictus (Sowerby) var. niedzwiedzkii (Uhlig); Naidin and Shimanskij, p. 197,
pi. 6, figs. 1-4.

1966 Scaphites (Hoploscaphites) constrictus (Sowerby); Birkelund, p. 741 et seq.; text-figs. 1, 7, 8.

1974 Hoploscaphites constrictus constrictus (Sowerby, 1818); Naidin, p. 173, pi. 58, figs. 7-9; pi. 61,
figs. 2-4.

1974 Hoploscaphites constrictus niedzwiedzkii (Uhlig, 1894); Naidin, p.174, pi. 58, figs. 10 and 1 1.

1979 Hoploscaphites constrictus (Sowerby, 1817); Birkelund, p. 55, text-figs. 2 (pars), 3d, e.

1979 Hoploscaphites constrictus crassus (Lopuski, 1911); Birkelund, p. 55.

EXPLANATION OF PLATE 14

Figs. 1-38. Hoploscaphites constrictus (J . Sowerby , 1817). 1 -4, MNHP R 1247b, microconch from ‘region de Ste
Colombe’. 5-9, MHNG unreg. (ex Pictet Collection), microconchs from Fresville. 10-12, SP 12,
unlocalized juvenile of intermediate inflation. 13-15, EMP unreg., microconch from Fresville; original of de
Grossouvre (1894, pi. 31, fig. 2). 16 18, BMNH C70646 (ex J. Sowerby, ex de Gerville Collection), juvenile
paralectotype from [Ste Colombe] ‘near Valognes’. 19-22, SP 3, macroconch of the compressed form from
Fresville. 23-26, EMP ‘b\ either very large microconch or small macroconch, from Orglandes. 27-30,
MNHP R 1247c, macroconch from ‘region de Ste Colombe’. 31 -33, SP 1 1, unlocalized juvenile macroconch.
34-38, SP 8, macroconch from Nehou.

Figs. 39-42. Fresvillia constricta gen. et sp. nov., IRSNB 10254 (ex Leriche Collection, IG 19859), holotype,
from Fresville.

All from Upper Maastrichtian Calcaire a Baculites of Manche, France. All x 1.

PLATE 14

KENNEDY, Hoploscaphites, Fresvillia

68

PALAEONTOLOGY, VOLUME 29

1979 Mesoscaphites grossouvrei Atabekian, p. 523 (nom. mu/.).

1979 Mesoscaphites kneri Atabekian, p. 523 (nom. nud.).

1980 Hop/oscaphites constrictus anterior Blaszkiewicz, p. 36, pi. 17, fig. 5; pi. 18, figs. 4-10.

1980 Hop/oscaphites constrictus crassus (Lopuski, 1911); Blaszkiewicz, p. 37, pi. 18, figs. 1-3, 11 -14.
1982 Hop/oscaphites constrictus (Sowerby, 1818); Birkelund, p. 19, pi. 3, figs. 1-14.

1982 Hop/oscaphites constrictus constrictus (Sowerby, 1817); Tsankov, p. 24, pi. 7, figs. 6-8.

71982 Scaphites (Hop/oscaphites) constrictus J. Sowerby; Martinez, p. 172, pi. 30, fig. 6.

1983 Hop/oscaphites constrictus ; Riccardi, p. 9.

Types. Sowerby obviously possessed more than one specimen of H. constrictus from Ste Colombe; Crick (1898,
p. 12) and Spath (1953, p. 13) referred to BMNH 43988 (PI. 15, figs. 18-20) as the type and the original of
Sowerby’s pi. A, fig. 1 , but this bears no resemblance to the figure (see text-fig. 9). Instead, as Phillips (1977, p. 90)
notes, BMNH C36733 (PI. 1 3, figs. 20-22) purchased from Mrs M. Sowerby in 1935 (together with the originals
of figs. 2 and 3 on the same plate) bears a close resemblance to the figure. It is herein designated lectotype of the
species. BMNH C43988 is a paralectotype, as are C70645-C70647.

Material. Fifty specimens in the BMNH, EMP, FSL, FSM, FSR, MNHG, MNHH, MNB, MNHP, OUM, and
SP Collections, including the original of Schliiter (1872, pi. 28, figs. 6-8) (MNB unreg.; PI. 13, figs. 1-3),
d’Orbigny (1842, pi. 129, figs. 8 and 9) (MNHP d’Orbigny Collection no. 7194; PI. 13, figs. 16 and 17), and de
Grossouvre (1894, pi. 31, figs. 1 and 2) (EMP unreg.; PI. 14, figs. 13-15). Localities mentioned are Manche,
Fresville, Orglandes, Ste Colombe, Nehou, Veuville, Chef-du-Pont, Port Filiolet, and Cussy.

Description. Highly variable and strongly dimorphic. Phragmocone very involute with tiny umbilicus. Whorl
section varies from compressed (whorl breadth to height ratio down to 0-5) and flat-sided with broadly rounded
ventrolateral shoulders and flattened venter (PI. 13, figs. 8-13; PI. 14, figs. 1-3, 24-26), to fat with swollen inner
flanks, convergent outer flanks, broadly rounded shoulders, and somewhat flattened venter (whorl breadth to

text-fig. 9. Copy of original illustration of Ammonites
constrictus J . Sowerby, 1817, pi. A, fig. 1; compare with
Plate 13, figs. 20-22.

EXPLANATION OF PLATE 15

Figs. 1-31. Hop/oscaphites constrictus (J. Sowerby, 1817). 1-3, FSR 1 (lex Seunes Collection), inflated yet finely
ribbed juvenile from Fresville. 4-6, EMP D (ex Deshayes Collection), microconch from Orglandes. 7-9,
BMNH C85008, microconch from 200 m south of Fresville Church. 10-13, BMNH C70647 (ex J. Sowerby,
ex de Gerville Collection), paralectotype from [Ste Colombe] ‘near Valognes’, phragmocone of largest
macroconch seen. 14-20, BMNH C43988, another paralectotype from same horizon, collection, and locality
as BMNH C70647, and corresponding to variety crassus of authors. 21-23, SP 6 (ex Leclerc Collection),
juvenile macroconch of the stout variety from Nehou. 24-29, MNHP R 1 272a (ex de Vibraye Collection),
stout juvenile macroconch from Ste Colombe. 29-31, EMP unreg., macroconch from Fresville, corre-
ponding to variety crassus of authors; original of de Grossouvre (1894, pi. 31, fig. 1) and holotype of
Mesoscaphites grossouvrei Atabekian, 1979.

All from Elpper Maastrichtian Calcaire a Bacu/ites of Manche, France. All x 1 .

PLATE 15

KENNEDY, Hoploscaphites

70

PALAEONTOLOGY, VOLUME 29

height ratio up to 0-95) (PI. 15, figs. 13, 10-31). Sixteen to twenty primary ribs arise at umbilical seam, are
flexuous, vary from feebly concave (PI. 13, fig. 1 1; PI. 1 5, fig. 16) to straight and prorsiradiate (PI. 13, fig. 9; PI. 15,
fig. 22) on inner flank, are generally convex at mid-flank, concave on outer flank and ventrolateral shoulder, and
feebly convex over venter. They subdivide low on flank, where long intercalatories also arise (e.g. PI. 15, fig. 19);
intercalatories and secondaries branch a second time (e.g. PI. 13, fig. 12; PI. 15, fig. 2) on outer flank, where
additional short intercalatories also insert, with much variation in style and strength between individuals; from
fifty-five (PI. 15, fig. 16) to around eighty (PI. 14, fig. 17) ribs on venter per whorl, ribs feebler and more numerous
in compressed individuals (PI. 13, figs. 8 12; PI. 14, figs. 8, 1 7, 25, 28, 32, 35) and generally fewer and coarser in
more inflated ones (PI. 15, figs. 16, 19, 22, 28, 30), with a few exceptions (PI. 15, figs. 2 and 13). Early phrag-
mocone whorls devoid of tubercles. Inflated individuals have up to five pointed ventral tubercles on last part of
phragmocone (PI. 15, fig. 19), with one or two non-tuberculate ribs between and a similar number of tiny nodes
on some compressed individuals (PI. 13, fig. 2; PI. 14, fig. 25). Other compressed individuals have tiny nodes on
every rib over last part of phragmocone (PI. 14, figs. 1-3); in others they appear lacking (PI. 14, figs. 7-9,
preservation is poor, however). A few specimens show umbilico-lateral or inner lateral bulla or bullae on last
part of phragmocone (PI. 15, figs. 19 and 30).

Body-chambers vary widely. In compressed microconchs (PI. 15, figs. 1-9) ribbing becomes very flexuous,
primary ribs develop sharp bullae at umbilical shoulder, and increase by branching and intercalation gives dense
ribs on venter (most or all of which bear tiny tubercles on shaft). Ornament declines on final hook, tubercles
disappear, and flanks are ornamented by fine striae only (PI. 14, figs. 2, 5, 8). Macroconchs of this type are
essentially similar (PI. 14, figs. 19 and 20). These forms grade into bluntly decorated individuals with broader
whorl section, like lectotype (a macroconch: PI. 13, figs. 20-22) where long, low umbilical bullae give rise to
groups of ribs that increase by branching and intercalation to link, in groups, to pointed ventrolateral nodes
(PI. 13, fig. 6; PI. 14, fig. 28) which, in some, elongate into prominent clavi (e.g. PI. 15, figs. 4-9, microconchs).
These specimens lack ventral ribs, unlike more compressed individuals (compare PI. 14, figs. 3 and 15), and
maintain distinct branching and intercalated ribs to aperture, although tubercles decline and are lost on final
part of hook. A few specimens of this type (including holotype) develop low swelling between ventral clavi on
early part of body-chamber (e.g. PI. 14, fig. 26). The most inflated body-chambers are decorated by distinct
umbilical or inner lateral bullae (PI. 15, figs. 18-20, 29-31) that may persist to aperture (PI. 13, fig. 18; PI. 15, fig.
19), but these are linked by every transition to specimens in which bullae are incipient only (e.g. PI. 14, fig. 28).
Ribs arise in groups from these bullae, branch and intercalate, and loop to ventral clavi which are separated by
smooth zones or effacing secondaries and intercalatories (PI. 15, figs. 19 and 30). In some specimens a distinct
siphonal swelling is crossed by fine riblets that loop between ventral clavi (PI. 15, fig. 18); in others ventral region
is virtually smooth between clavi. Ribs and tubercles may decline towards aperture, or persist (PI. 15, figs. 19
and 31).

Suture lines (text-fig. 1 1 a-h) vary in detail only and are consistently simple and little incised.

Discussion. I can draw no lines between the specimens from the Calcaire a Baculites\ there appears to
be every gradation in whorl compression, ribbing, and tuberculation style. Scaphites multinodosus
(Hauer, 1858) (p. 9, pi. 1 (2), figs. 7 and 8) from the Maastrichtian of Neuberg, Styria, is a small
macroconch of the present species. It occurs with Pachydiscus neubergicus (Hauer, 1858) and is
significantly older than the present material. (The S. multinodosus of Hauer 1866, p. 306, pi. 1, figs. 7
and 8 is a Trachyscaphites; fide Cobban and Scott 1964.) I agree with Birkelund (1982) and
Makowski (1963) that S. niedzwiedzkii Uhlig, 1894 (p. 220, text-fig. 2) is a microconch of the present
species. H. c. crassus Lopuski, 1911 (pp. 115, 134, pi. 2, figs. 5 and 6; pi. 3, figs. 1 and 2) can be matched
with the coarsely ribbed specimens described here (PI. 1 5, figs. 18-20, 29-31) and is inseparable from
constrictus even at sub-specific level. H. c. vulgaris Nowak, 1911 (p. 583, pi. 32, fig. 6?; pi. 33, figs.
8-12) is equally inseparable. Mesoscaphites grossouvrei Atabekian, 1979 (p. 523) ( nomen nudum) has,
as holotype, the original of de Grossouvre (1894, pi. 31, fig. 1). This specimen (PI. 15, figs. 29-31) is
merely a coarsely ribbed variant of 'crassus' type and is Upper, rather than Lower Maastrichtian as
suggested by Atabekian. ‘M.’ kneri Atabekian, 1979 (p. 523) ( nomen nudum) has the original of Kner
(1852, pi. 15, fig. 13) as holotype and is also a constrictus.

H. c. anterior Blaszkiewicz, 1980 (p. 36, pi. 17, fig. 5; pi. 18, figs. 4-10) from the Lower
Maastrichtian of Poland was separated from H. constrictus sensu stricto on the basis of a smaller
apertural angle (95°), ‘not so close contact of body chamber and phragmocone and a smaller degree
of flattening of the ventral side’ (Blaszkiewicz 1980, p. 36), and a lower stratigraphic position. The

KENNEDY: UPPER MAASTRICHT! AN AMMONITES

71

text-fig. 10. External sutures, a, Fresvillia constricta gen. et. sp. nov., IRSNB 10254. b, Hoplitoplacenticeras
lasfresnayanum (d’Orbigny, 1841), SP unreg. c, Acanthoscaphites verneuilianus (d’Orbigny. 1841), EMP unreg.

D, Acanthoscaphites sp., MNHP R1270.

holotype is no more than a variant of the present species, resembling closely the individual shown in
Plate 13, figs. 5-7, and is treated as a synonym.

H. tenuistriatus ( Kner, 1848) (p. 10, pi. 1, fig. 5), originally described from Kieselka near Lemberg
(now Lvov), characterizes a level well below that of the present material ( fide Birkelund 1982). It has
been treated as a separate species (as by Kner; Favre 1869; Birkelund 1982) or as a subspecies of
constrictus (as by Nowak 1909, 191 1; Wolansky 1932; Naidin 1974). It has a rather coarsely ribbed
phragmocone and a very finely ribbed body-chamber lacking nodes. The last two features separate it
from constrictus and I regard it as specifically distinct, although Nowak ( 191 1 , pi. 33, fig. 13) figured
what he believed to be tenuistriatus with nodes.

Acanthoscaphites schmidi Birkelund, 1982, from the middle of the Maastrichtian at Hemmoor,
north-west Germany, seems rather to be a Hoploscaphites. The holotype (Birkelund 1982, pi. 1,
figs. 7-9) is a microconch which has ventral and weak siphonal tubercles on the phragmocone
and early body-chamber, with very fine ribs on the venter and ventrolateral parts of the body-
chamber. As described above, some H. constrictus develop a feeble siphonal node (e.g. PI. 15,
fig. 18) while some specimens, discussed further below (e.g. PI. 16, figs. 1-6, 11-14) are very
close indeed to Birkelund’s species but have a simple, Hoploscaphites suture; these may be
further variants of constrictus , as siphonal tubercles appear more than once in Upper Cretaceous
Scaphites.

72

PALAEONTOLOGY, VOLUME 29

text-fig. 11. External sutures, a-h, Hoploscapliites constrictus (J. Sowerby, 1817). a, g, BMNH C43988;
b, SP 8; c, E, SP 9; d, h, SP 1 1; f, MNHP R1247c. i-k, Hoploscapliites sp. I, J, EMP A; K, SP 13.

KENNEDY: UPPER MAASTRICHTIAN AMMONITES

73

Other Hoploscaphites species bear little resemblance to the present form and are unlikely to be
confused with it.

S. constrict us is held to range from just above the base of the Maastrichtian to the top of the stage,
and Birkelund (1979, 1982) has provided the only attempt at recognizing vertical changes in
ornament on the basis of material from the Danish Chalk. Forms referred to the ‘variety’ crassus ,
which occur in the present material, are restricted to the Belemnella casimirovensis Zone, while there
is a decrease in the number of ribs on the last 10 mm of the body-chamber as one ascends the
Maastrichtian, from six (in ‘var. crassus') to about ten in finer ribbed individuals from the Calcaire a
Baculites (much as in the Danish casimirovensis Zone material).

The range of size in dimorphs of this species was measured by Makowski (1963) who described
a collection of thirty-two specimens from the Upper Maastrichtian of Kazimiez on the Vistula.
The twenty-two macroconchs (69 %) ranged from 47 to 68 mm; the ten microconchs (31 %) from
22 to 35 mm. Of twenty-three measurable specimens from the Calcaire a Baculites , fifteen
(65%) are macroconchs ranging from 39 to 56 mm and eight (35%) microconchs, ranging from
25 to 34-5 mm length. The largest complete specimen is the lectotype which has a phragmocone
34-5 mm in diameter. BMNH C70647 (PI. 15, figs. 10-13) is a complete phragmocone 43 mm
in diameter, suggesting a complete shell 70 mm long, so that there is a fair agreement with the
Polish material.

Occurrence. The species first appears in the Lower Maastrichtian. At Kronsmoor in north Germany the first
specimen appears 3-5 m to 50 m above the base of the Belemnella lanceolata Zone, while in Denmark it ranges to
the top of the B. casimirovensis Zone (which is, however, incomplete). The most southerly records of the species
are in the Upper Maastrichtian of the Petite Pyrenees (France) and northern Spain (Ernst Collection; ? the pre-
Pyreneean region of Lleida: Martinez 1982, p. 1 72, pi. 30, fig. 6). It occurs at all the Calcaire a Baculites localities
in the Cotentin, throughout the Nekum and Meersen Chalk in the Maastrichtian type area, and in the Calcaire
de Kunraed. It occurs widely in the Germanies, Denmark, southern Sweden, Poland, Austria (Styria), Bulgaria,
and the USSR (Carpathians, Donbas region, Transcaspia, Kopet Dag).

Hoploscaphites sp.

Plate 13, figs. 14 and 1 5; Plate 16, figs. 1-6, 11-14, 18, 19; text-fig. 1 1 1 k

Material. Seven specimens, FSR2 from Orglandes; MNF1P 1247 are from the ‘region de Ste Colombe’; FSR3
from ‘Manche’; EMP ‘A’ from Orglandes; SP 13 from an unspecified locality; FSM 3 from Chef-du-Pont,
Fresville; and MHNG (ex Pictet Collection) from Fresville.

Description. Phragmocone as in H. constrictus with crowded branching and intercalated ribs, with up to five
ventrolateral tubercles and two umbilical bullae at end of phragmocone (PI. 16, fig. 4). Body-chamber initially
with variable umbilical or umbilicolateral tubercles and low, broad ribs (PI. 13, fig. 14; PI. 16, figs. 4, 12, 19),
strong ventral clavi (PI. 13, fig. 15; PI. 16, figs. 1 , 1 1 , 13, 18), and blunt siphonal nodes (PI. 16, figs. 1 , 13, 18). No
ventral ribs or riblets. Tubercles lost on last half of body-chamber where ribs weaken (PI. 16, figs. 14 and 19) or
become very fine indeed (PI. 16, figs. 3, 4, 12).

Suture simple (text-fig. 1 1 1 k), as in H. constrictus.

Discussion. I originally thought these specimens to be Acanthoscaphites. The suture is very simple, as
in H. constrictus , while the siphonal node is coarse and blunt. Given the presence of an incipient
siphonal node in some H. constrictus (e.g. PI. 15, figs. 18 and 29) the present material is probably no
more than a further variant. There is a strong resemblance to H. schmidi (Birkelund, 1982) (p. 17,
pi. 1, figs. 7-10; pi. 2, figs. 1-4) from the middle Maastrichtian of Hemmoor, north Germany The
holotype, a microconch, is closely similar, but the detail of ventral tubercles and ribs on the phragmo-
cone and the delicate secondary ribs on the body-chamber are distinctive. The large, presumably
macroconch fragments referred to H. schmidi by Birkelund (1982, pi. 2, figs. 1 -4) are far larger than
any H. constrictus known, suggesting it to be a giant, short-lived stock. The present material thus
represents a significantly later parallel departure in ornament from typical H. constrictus.

Occurrence. As for material.

74

PALAEONTOLOGY, VOLUME 29

Genus acanthoscaphites Nowak, 1911

Type species. Scaphites tridens Kner, 1848, p. 10, pi. 2, fig. 1, by the subsequent designation of Diener (1925,
p.’ 205).

Discussion. Review of the genus is deferred pending restudy of the type species.

Occurrence. Upper Campanianf?) and Maastrichtian of western, central, and eastern Europe, and the USSR.

Acanthoscaphites verneuilianus (d'Orbigny, 1841)

Plate 16, figs. 15-17; text-fig. 10c

1841
non 1842
1850
1894
1925

Ammonites verneuilianus d’Orbigny, p. 329, pi. 98, figs. 3-5.
Ammonites nodifer von Hagenow, p. 565, pi. 9, tig. 19.

Ammonites verneuilianus d’Orbigny; d’Orbigny, p. 212.

Scaphites verneui/i d’Orbigny sp.; de Grossouvre, p. 253, pi. 36, fig. 2.
Scaphites verneuili d’Orbigny; Diener, p. 204

Type. d’Orbigny’s account indicates that this species was discovered by de Gerville in the ‘Craie de Fresville, pres
de Valognes (Manche)’. There are no specimens of this species in his collections, and the unregistered EMP
specimen figured by de Grossouvre (1894, pi. 36, fig. 2) and reillustrated here (PI. 16, figs. 15-17)1 take to be the
holotype by monotypy.

Dimensions

Holotype
MNHP R127I

D

46-8(100)

57-5(100)

Wb Wh Wb.Wh U

-(— ) 24-4(52-0) - 5-4(11-5)

25-6(44-5) 31-8(55-3) 9-5(16-5)

Description. Coiling very involute with tiny, deep umbilicus. Umbilical wall rounded and undercut on internal
mould; umbilical shoulder narrowly rounded, flanks broadly rounded, converging to broadly rounded venter.
Greatest breadth close to umbilical shoulder, estimated whorl breadth to height ratio 0-78. Eleven narrow,
distant primary ribs on outer whorl; these arise at umbilical seam, are feebly concave across umbilical shoulder,
and straight and prorsiradiate across flanks. They may give rise to fine secondary ribs on outer flank, while up to
six fine intercalated ribs, both single and branching, arise at various points on flank. They are set at an acute
angle to succeeding primary rib, as though they were secondaries arising from adapical face of that primary.
Secondary ribs pass across venter undiminished, but primary ribs decline markedly in strength across this region.
At smallest diameter visible on holotype only primary ribs each bear feeble ventrolateral bulla. These persist, and
as size increases ventrolateral tubercles appear first on one, then on two secondary ribs. At same point in
development a second tubercle appears on ventrolateral shoulder in inner ventrolateral position. At diameter of
approximately 27 mm, rounded siphonal tubercles appear, corresponding in position to ventrolateral tubercles.

Discussion. d’Orbigny’s figure is reasonably accurate. Apart from the holotype, described above,
there is a second, large specimen, MNHP R1271, from Fresville {ex de Vibraye Collection) that may
belong here (PI. 16, figs. 20 and 21). It shows a rather similar ventrolateral ornament at a diameter
comparable to that of the holotype, but beyond this the tubercles strengthen, while a mid-lateral bulla
appears on the primary ribs (PI. 16, fig. 21). Unfortunately poor preservation precludes fuller

EXPLANATION OF PLATE 16

Figs. 1-6, I 1 14, 18, 19. Hoploscapliites sp. 1, 4, 13, EMP ‘A’ {ex Deshayes Collection), from Orglandes. 3,
FSM 3, from ‘Chef du Pont, Fresville, Orglandes’. 5, 1 1, 12, MNHP 1247a, from Ste Colombe. 2, 6, 14, FSR 3,
from ‘Manche’. 18 and 19, FSR 2, from Orglandes.

Figs. 7-10. Acanthoscaphites sp., MNHP R12470 (exde Morgan Collection), from Fresville.

Figs. 15- 17. A. verneuilianus (d'Orbigny, 1841), EMP unreg., holotype, from Fresville.

Figs. 20 and 21. A. cf. verneuilianus (d’Orbigny, 1841), MNHP R12471 {ex de Vibraye Collection), from
Fresville.

All from Upper Maastrichtian Calcaire a Baculites of Manche, France. All x 1.

PLATE 16

KENNEDY, Hoploscaphites , Acanthoscaphites

76

PALAEONTOLOGY, VOLUME 29

description, but it appears that the specimen bears feeble umbilical and lateral bullae, plus strong
inner and outer ventrolateral tubercles from c. 50 mm onwards. A third specimen, MNHP R 12470,
also from Fresville (ex Morgan Collection) is shown in Plate 16, figs. 7-10. The inner whorls to 27 mm
closely resemble those of the holotype, but beyond this the ribs coarsen markedly (PI. 16, fig. 8) with
primaries separated by a single secondary; all ribs bear outer ventrolateral and siphonal tubercles
with occasional intercalated nontuberculate riblets (PI. 16, fig. 10). These differences from the type
suggest the presence of a second species, but with so few specimens, and knowing the range of
variation shown by e.g. H. const rictus, described above, it is recorded as Acanthoscaphites sp.

These small species with multiple tuberculation on the phragmocone are very different from the
giant type species, 5. tridens Kner, 1 848, as is revealed by study of the fine specimens (in NHMW and
GBA Collections) from Nagorzany, Galicia, which include the originals of Favre (1869), where
phragmocones lack tubercles. There are closer similarities to S. trinodosus (Kner, 1848) (p. 11, pi. 2,
fig. 2) in which there are feeble to obsolete umbilical bullae on nuclei, strengthening on the body-
chamber, and ventrolateral and siphonal tubercles on all but the early whorls; the absence of inner
ventrolaterals immediately distinguishes it from the present form, however.

‘S’.’ pangens Binkhorst, 1861 (p. 32, pi. 5o3, fig. 1; see also de Grossouvre 1908, p. 37, pi. 11, figs. 1
and 2) has relatively coarse primary ribs on the flank, all of which bear ventrolateral clavi from an
early stage, fine looped and intercalated ventral ribbing, and lacks a siphonal tubercle on the
phragmocone.

A. innodosus Naidin, 1974 (p. 178, pi. 62, fig. 1) lacks phragmocone tubercles and is a giant species.
A. bispinosus Nowak, 1911 (p. 577, pi. 32, figs. 1-3) and A. quadrispinosus (Geinitz, 1850) (pi. 7, fig. 2;
pi. 8, fig. 2) are both large species and lack multiple tubercles on the phragmocone.

Occurrence. Upper Maastrichtian of the Cotentin.

AGE

That the Calcaire a Bacu/ites is Maastrichtian is not disputed. There is, however, no a priori reason to
assume that the whole sequence belongs to one faunal zone, or that the various outliers are all of the
same age. Conversely, the facies of the succession is such that only a short time interval may be
represented. There is at present no satisfactory ammonite zonation for the Maastrichtian of north-
west Europe and, in consequence, the dating of the succession is most usefully discussed in terms of
the ‘standard’ belemnite succession worked out in the White Chalk sequence (e.g. Christensen 1979,
but note that Schulz 1979 has proposed a more refined succession for the Lower Maastrichtian):

Upper Maastrichtian

Belenuie/la casimirovensis
Beleinnitella junior

Lower Maastrichtian

Belemnella occidentalis
Belenmella lanceolata

Belemnites occur in the Calcaire a Bacu/ites , but I have only found fragments in museum
collections. Dr W. K. Christensen (Copenhagen) examined five fragments from Fresville-Orglande
in the FSM Collections. On the basis of the Schatzky distance and alveolar angle he concludes them
to be a Belemnitella , the small fissure angle resembling that of some B. junior, a species that ranges
through the Upper Maastrichtian.

Echinocorys are valuable stratigraphic indicators in White Chalk successions and are also present
in the Calcaire a Bacu/ites', I have shown three specimens from Fresville (FSM and SP Collections) to
Professor G. Ernst (Berlin), Mr C. J. Wood (London), and Mr N. B. Peake (Norwich) who all agree
that they are probably Upper Maastrichtian; Mr Peake also suggests that they are probably
casimirovensis Zone forms. Bryozoans were dealt with by Voigt (1968); in a letter dated 5 August 1984
Professor Voigt confirmed his view that they indicate an Upper Maastrichtian horizon.

Foram assemblages were last investigated by Holler (1960) who examined a specimen from Port
Filiolet and one from Fresville, concluding that the former came from a slightly higher stratigraphic
level than the latter, but that both were Upper Maastrichtian. Hofker particuarly drew attention to

KENNEDY: UPPER MAASTRICHT! AN AMMONITES

77

similarities with the sequence in the Maastricht area, suggesting a correlation with the sequence
between divisions Cr4 and Mb of Uhlenbroek (1912), i.e. Upper Maastrichtian. Following the recent
revision of the belemnites of the Maastricht area by Schulz and Schmid (1983) this would place the
Port Filiolet and Fresville samples within the Belemnitella junior Zone of the lower Upper
Maastrichtian.

What is the ammonite evidence? There are so few specimens from some localities that absence of
taxa is probably of little significance. What I do find significant is the presence, at all localities, of
abundant Baculites anceps. De Grossouvre ( 1 90 1 , p. 286) recorded Baculites as being abundant at the
base of the Carriere de Veauville and ranging to near the top of the sequence. Birkelund (1979) has
shown this species to be restricted to the upper Upper Maastrichtian Belemnella casimirovensis Zone
in the expanded Danish chalk successions, while other Calcaire a Baculites species that are restricted
to this zone in Denmark are B. vertebralis and forms of S. constrictus referred to the variety crassus.
The latter is also confined to the upper part of the casimirovensis Zone in Poland (Blaszkiewicz 1980),
suggesting that the Calcaire a Baculites at localities yielding this form (Ste Colombe, Nehou,
Fresville) at least extend to high in the casimirovensis Zone. The variety crassus also occurs in the
upper part of the Meersen Chalk in the Maastricht area, associated with rare Belemnella
casimirovensis and more frequent Belemnitella junior , confirming this dating.

Pachydiscus gollevillensis, P.jacquoti, and Anapachy discus fresvillensis, typical Calcaire a Baculites
species, occur in the Calcaire de Kunraed of Kunraed near Maastricht associated with rare Baculites
anceps , and abundant B. vertebralis (i.e. the reverse of their relative abundance in the Cotentin),
numerous H. constrictus (none of which correspond to the variety crassus ), and a number of other
species of lesser stratigraphic value (Kennedy 19846). Drs M. G. Schulz and F. Schmidt tell me that
they have seen several Belemnitella of the junior group from the Calcaire de Kunraed, but as this
group ranges through the Upper Maastrichtian, this alone is of limited value. A. fresvillensis also
occurs in the Nekum Chalk of the Maastricht area. Belemnitella of the junior group are common in
the basal part of the Nekum Chalk and range from low in the Viljlen Chalk to the top of the Meersen
Chalk, with, as already noted, Belemnella casimirovensis appearing only in the upper part of the
Meersen Chalk (Schulz and Schmid 1983). This suggests that the pachydiscids characteristic of the
Calcaire a Baculites appear in the junior Zone and, taken with Hofker’s correlation, indicate that
the Calcaire a Baculites spans the upper part of the junior Zone and extends locally into the upper
part of the casimirovensis Zone.

The evidence from the Danish and Dutch sequences are thus in conflict: the former suggests that
the Calcaire a Baculites is exclusively within the casimirovensis Zone, while the latter suggests that it
extends down into the upper part of the junior Zone, unless the appearance of rare Belemnella
casimirovensis in the Maastricht area is significantly later than in the Danish White Chalk succession.

Irrespective of these problems, there seems little doubt that the Calcaire a Baculites ammonites
indicate an exclusively Upper Maastrichtian date for the sequence, and that locally the sequence
extends high into the upper Upper Maastrichtian Belemnella casimirovensis Zone. There are no
exclusively Lower Maastrichtian ammonites and, among the many scaphitids, no H. tenuistriatus
(Kner, 1848), a form that straddles the Lower/Upper Maastrichtian boundary in White Chalk
successions (Birkelund 1982). Hoplitoplacenticeras lasfresnayanum , known from a single specimen,
represents a genus known only from the Upper Campanian. It is quite distinct from other species
of the genus and is taken to be a late survivor; there is no evidence for the Campanian in the fauna
of the unit.

Acknowledgements. Many colleagues have helped in the assembly of ammonites from the Calcaire a Baculites ,
and 1 thank D. Phillips, M. K. Howarth, and H. G. Owen (London), D. Pajaud and J. Sornay (Paris), G. Breton
(Le Havre), P. Moreau (Poitiers), J. P. Thieuloy (Grenoble), P. Juignet (Rouen), G. Mary (Le Mans), A. Prieur
(Lyon), G. Thomel (Nice), A. Dhondt (Brussels), D. Decrouez (Geneva), J. Wiedmann (Tubingen), G. Flajs
(Aachen), H. Remy (Bonn), and H. Jaeger (Berlin). W. K. Christensen (Copenhagen) identified belemnites;
G. Ernst (Berlin), C. J. Wood (London), and N. B. Peake (Norwich) identified echinoids. T. Birkelund
(Copenhagen), P. Ward (Davis, California), and C. W. Wright (Seaborough, Dorset) provided valuable advice;
M. G. Schulz (Kiel) and F. Schmid (Hanover) provided data on the belemnites of the Maastricht region. The

78

PALAEONTOLOGY, VOLUME 29

financial support of NERC, the Royal Society, and the British Council is gratefully acknowledged; I thank the
staff of the Department of Earth Sciences and Geological Collections of the University Museum, Oxford, for
technical assistance.

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western interior of Canada. Bull. geol. Surv. Can. 354, 103 pp., 26 pis.

82

PALAEONTOLOGY, VOLUME 29

SCHLuter, c. 1871-1876. Cephalopoden der oberen deutschen Kreide. Palaeontographica , 21, 1-24, pis. 1-8
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-Ernst, G., ernst, h. and schmid, f. 1984. Coniacian to Maastrichtian stage boundaries in the standard
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and schmid, f. 1983. Das Ober-Maastricht von Hemmoor (N-Deutschland): Faunenzonen-Gliederung
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seunes, j. 1890a. Contribution a l’etude des cephalopodes du Cretace Superieur de France. 1. Ammonites du
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— 1891. Contribution a l'etude des cephalopodes du Cretace Superieur de France. I. Ammonites du
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sharpe, d. 1853 1857. Description of the fossil remains of Mollusca found in the Chalk of England. I,
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shimizu, s. 1935. The Upper Cretaceous cephalopods of Japan, Part I. J. Shanghai Sci. Inst. (2), 1, 159-226,
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sowerby, j. 1812-1822. The mineral conchology of Great Britain. 1, pis. 1-9 ( 1812), pis. 10-44(1813), pis. 45-78
(1814), pis. 79 102 (1815); 2, pis. 103 114 (1815), pis. 115-150 (1816), pis. 151-184, A, 185, 186 (1817),
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4, pis. 307-3 18 (1821), pis. 319-383 (1 822). The author, London.

sowerby, j. de c. 1823-1846. The mineral conchology of Great Britain (continued). 4, pis. 384-407 (1823);

5, pis. 408-443 (1823), pis. 444-485 (1824), pis. 486-503 (1825); 6, pis. 504-544 (1826), pis. 545-580 (1827),
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pis. 629-643 (1844), pis. 644-648 (1846). The author, London.

spath, l. f. 1921. On Cretaceous Cephalopoda from Zululand. Ann. S. Afr. Mus. 12, 217-321, pis. 19-26.
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- 1923. A monograph of the Ammonoidea of the Gault. Palaeontogr. Soc. ( Monogr .), part 1, 1 -72, pis. 1 4.

1925. On Senonian Ammonoidea from Jamaica. Geol. Mag. 62, 28-32, pi. 1.

1926. On new ammonites from the English Chalk. Ibid. 63, 77-83, table.

— 1940. On Upper Cretaceous (Maastrichtian) Ammonoidea from Western Australia. Jl. R. Soc. West . Aust.
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— 1953. The Upper Cretaceous cephalopod fauna of Grahamland. Scient. Rep. Br. Antarct. Surv. 3, 1-60,
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stoliczka, F. 1863-1866. The fossil cephalopoda of southern India. Ammonitidae with revision of the
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KENNEDY: UPPER MAASTRICHT! AN AMMONITES

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wright, c. w. 1953. Note on Cretaceous ammonites. I. Scaphitidae. Ann. Mag. nat. Hist. (12), 6, 473-476.

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yabe, h. 1921. In yabe, h. and shimizu, s. Notes on some Cretaceous ammonites from Japan and California. Sci.
Rep. Tdhoku Univ. (2), 5, 53-59 (1-7), pis. 8 and 9.

— 1927. Cretaceous stratigraphy of the Japanese Islands. Ibid. 11, 27-100, pis. 3-9.

— and shimizu, s. 1926. A study on the genus ' P arapachy discus' . Proc. imp. Acad. Japan , 2, 171-173.
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ix + 373 pp., 82 pis.

zittel, k. a. von. 1884. Handbuch der Palaeontologie . . . Abt. 1, 2, (Lief 3), Cephalopoda , 329-522. R.
Oldenbourg, Munich and Leipzig.

— 1895. Grundziige der Palaeontologie ( Palaeozoologie ), vii +972 pp. R. Oldenbourg, Munich and Leipzig.

W. J. KENNEDY

Typescript received 15 January 1985
Revised typescript received 8 May 1985

NOTE ADDED IN PROOF

I have recently discovered five additional belemnite fragments from the Calcaire a Baculites in the SP Collections
(exde Gerville Collection). Dr W. K. Christensen tells me that these include unequivocal specimens of the Upper
Maastrichtian Belemnitella junior.

Geological Collections
University Museum
Parks Road
Oxford OX1 3PW

PALAEOECOLOGY AND HISTORY OF THE
CALCEOCRINIDAE (PALAEOZOIC CRI NOIDEA)

by WILLIAM I. AUSICH

Abstract. The morphologically divergent and long-ranging Calceocrinidae (inadunate crinoids, middle Or-
dovician to early Permian) are reinterpreted to have been leeward, passive, suspension feeders. Calceocrinid
success is measured relatively by species diversity and by the relationship of calceocrinid species diversity to
total crinoid generic diversity. The major change in calceocrinid importance occurred immediately after the
Silurian, and this decline is judged to have been the consequence of biotic interactions. Both increased
predation pressure and competition from fenestrate bryozoans are offered as potential causes for the decline;
of the two, competition for living sites and exclusion by habitat modification by fenestrates is favoured.
Accordingly the Devonian calceocrinid decline is argued to be the result of partial ecologic replacement of
calceocrinids by fenestrate bryozoans. This study provides an example illustrating the impact that ecologic
processes may have in evolutionary time.

The Calceocrinidae are among the most morphologically divergent groups of crinoids. Rather than
having aboral cup plates in circlets above the column arranged radially about the oral-aboral axis,
members of this crinoid family have their two circlets of cup plates articulated with one another
along a hinge. The radial plates and arms lay over the basal plates and column. In addition the
five-arm body plan, characteristic of most crinoids, was altered to either a four or three-arm
arrangement. The total morphological change was toward a bilaterally symmetrical crown with
highly modified cup and arms. This body plan proved successful for approximately 230 million
years. The first calceocrinids appeared in the middle Ordovician (Blackriverian, Llanvirn), and they
are last recorded from the early Permian (Leonardian, Artinskian). Their absolute success varied
during this time: they were relatively quite abundant and diverse from the middle Ordovician
through to the Silurian, but their role in echinoderm communities declined in the Devonian, and
they met apparent near extinction in the early Mississippian. Calceocrinids have not been reported
from middle Mississippian to early Permian rocks. It is my purpose here to examine the palaeo-
ecology of calceocrinids and to offer explanations for their evolutionary history.

CALCEOCRINID AUTECOLOGY

Scientists tend to spend more time studying and debating various aspects of morphologically
unusual taxa than ‘normal’ taxa. This has been true for crinoids, as illustrated by the calceocrinids.
Four main autecological modes have been suggested for calceocrinids: ‘drooper’, ‘runner’, ‘weather-
vane’, and ‘kite’ modes.

The drooper mode is the paradigm of a typical stalked crinoid with an erect column (text-fig. 1c,
d). In this posture the closed calceocrinid crown would have hung vertically down along the column,
and an open crown would have been orientated horizontally (Ringueberg 1889).

An alternative to the drooper mode was proposed by Jaeckel (1918). This reconstruction, the
runner mode (text-fig. 1a), has received wide support (Springer 1926; Ramsbottom 1952; Moore
1962; Brower 1966, 1977; and others). According to the runner theory the highly modified crown
was an adaptation for life with the column prostrate along the sea floor. In a closed posture the
arms would have been folded over the column along the substratum; in the open posture the arms
would have been positioned vertically in the water column. Calceocrinids have been reconstructed
with the arms orientated such that currents impinged on the oral side of the arms (Jaeckel 1918).

(Palaeontology, Vol. 29, Part 1, 1986, pp. 85 99.|

86

PALAEONTOLOGY, VOLUME 29

text-fig. 1 . Various reconstructions of modes of life for calceocrinids. a, traditional runner mode
with currents striking the oral surface of arms (Jaekel 1918; followed by most subsequent workers).
b, weather-vane mode, a variation of the runner mode (Kesling and Sigler 1969). c, d, drooper
mode, an interpretation consistent with the upright posture of most stalked crinoids (Ringueberg
1889). e, kite mode, a variation of the runner mode (Breimer and Webster 1975). f, runner mode,
with currents striking the aboral arm surface, proposed herein.

The weather-vane mode (Kesling and Sigler 1969) and kite mode (Breimer and Webster 1975) are
variations of the runner mode. Both are based on the assumption that currents struck the oral side
of the arms. Kesling and Sigler (1969) proposed that open calceocrinid arms caught the current
and shifted, like a weather-vane, depending upon the prevailing current direction (text-fig. 1b).
Breimer and Webster (1975) included calceocrinids in their discussion of current-derived lift for
crinoids. They considered that calceocrinids would have lain on the substratum in slack currents,
and that in higher current conditions the open crown would have gained lift and been elevated
above the sediment (text-fig. 1e).

In addition to these general reconstructions, Schmidt (1934) proposed that the five-armed
Devonian calceocrinid, Senariocrinus, was a free-swimming pelagic crinoid.

Preferred model

Living crinoids orientate their filtration fans perpendicular to unidirectional currents. According to
the drooper model the open arms of a calceocrinid would have been orientated horizontally, or
nearly so, unlike living crinoids. It seems unlikely that the calceocrinid stock would have developed
such a divergent morphology to lead the same erect, suspension-feeding life style as that of other
crinoids. This suggestion against the drooper theory is supported by morphological criteria. Brower
(1966, 1977) has reported two specimens of Calceocrinus longifrons Brower with the arm length

AUSICH: PALAEOZOIC CRINOIDS

87

greater than the stem length. Although the stem in most calceocrinids is relatively much longer,
these specimens must have been recumbent along the sea floor. Ausich (1984a) described an in situ
holdfast of Trypherocrinus brassfieldensis Ausich that must have conformed to the runner theory.
In this specimen the distal column projected vertically from the sediment, but the column orientation
was changed to horizontal by a series of wedge-shaped columnals. This stem arrangement resulted
in an obligate recumbent posture. Similarly, Eckert (1984) and Brett (1985) reported calceocrinid
holdfasts with the column facet orientated vertically, thereby dictating a recumbent stem posture.

Although inconclusive alone, taphonomic evidence further supports the suggestion that cal-
ceocrinids lived along the bottom. In collections made by the author from the lower Silurian
Brassfield Formation, Ohio (Ausich 1984a), and the lower Mississippian Edwardsville Formation,
Indiana (Ausich et al. 1979), calceocrinids were among taxa most commonly well preserved. The
typical preservation of a nearly complete crown, commonly with stem attached, may be the result
of the fact that calceocrinids lived on the bottom— where they would have been buried alive and
preserved whole more easily than if they stood erect.

The weather-vane and kite modes (modifications of the runner mode) both seem unlikely. No
known calceocrinid holdfasts possess an articulation that would have afforded the rotational move-
ment implied by the weather-vane model. As argued by Eckert (1984), rather than having a
horizontal holdfast-column articulation that would have allowed maximum rotation, many cal-
ceocrinid holdfast-column articulations are at a steep angle. Brower (1977) concluded that the kite
mode may have been possible for some calceocrinids, some of the time, while Brett ( 1981 ) considered
that the kite mode could only have been effective in high energy environments. Even in such settings
it seems unlikely that the large calceocrinid crowns could have acquired sufficient lift from the
currents. In addition, the kite mode implies that the column acted as a flexible tether rather than a
rigid support structure. The latter seems much more plausible and is consistent with the functional
morphology of living crinoids.

Both the weather-vane and kite modes require that calceocrinids were orientated with the oral
side of their arms facing the current — the classic interpretation of calceocrinid orientation to
currents. It stands in contrast, however, to what is known about both crinoid feeding and passive
suspension feeding among other marine invertebrates. It is argued below that calceocrinids were
probably orientated like modern crinoids, with ambulacral grooves on the down-current side. This
interpretation further denies the weather-vane and kite modes.

In summary, from ideas on suspension feeding and morphological constraints, it appears that
calceocrinid morphology was the result of a series of adaptations for life on the bottom with the
stem prostrate along the sea floor, as first suggested by Jaekel (1918).

Orientation to current

From the time of Jaekel’s (1918) original calceocrinid work to the present, calceocrinids have been
reconstructed such that feeding currents impinged upon the oral (ambulacral) side of the arms. This
interpretation has persisted despite the fact that living crinoids are now known to be leeward passive
suspension feeders (feeding currents strike the aboral side of the arms) (Magnus 1963, 1964, 1967;
Macurda and Meyer 1974; Warner 1977; Meyer 1982). It is appropriate to re-examine this aspect
of calceocrinid autecology.

Living crinoids located in unidirectional current conditions typically form either planar or para-
bolic filtration fans (Meyer 1982), and food is captured by tube feet in the ambulacral grooves on
the down-current side of the fan (Macurda and Meyer 1974; Meyer 1973, 1982; Byrne and Fontaine
1981). Comatulid crinoids with multi-layered fans rotate certain arms so that all ambulacral grooves
are in this leeward position. In tidal dominated settings with bidirectional currents, comatulid
crinoids rotate their pinnular ambulacra to keep them in a leeward position (Meyer 1982). This
preference for leeward food capture is common among many suspension feeders. Warner (1977)
argued from experimental evidence that passive suspension feeders must utilize leeward food capture
for maximum suspension-feeding efficiency and cited examples of leeward passive suspension feeding
among hydroids, bryozoans, and crinoids.

PALAEONTOLOGY, VOLUME 29

Although absolute adherence to modern analogues is not a wise philosophy, there is no compelling
morphological reason to suggest that calceocrinids abandoned the leeward passive suspension
feeding mode. The construction of arm plates and ambulacral grooves appears to be similar to
other Palaeozoic crinoids. Arm modifications are only modifications in arm branching style, which
is an extremely common evolutionary trend among crinoids. Consequently, modification of the
arms and aboral cup is more readily explained as an adapatation for life on the substratum rather
than as a deviation from leeward suspension feeding. It is perhaps counter-intuitive to interpret
calceocrinids as leeward suspension feeders, but the orientation of living crinoids was misinterpreted
by intuitive judgement until in vivo observation demonstrated their leeward orientation.

The runner mode with a leeward ambulacral orientation is preferred (text-fig. If) because it is
consistent with behaviour of both living crinoids and most other passive suspension feeding organ-
isms. In a leeward orientation, juvenile calceocrinids would have grown into the current (which is
reasonable for a rheophilic organism), and the action of unusually high currents would have pushed
the arms into a closed, protected resting posture on the stem. Known occurrences of calceocrinids are
in settings that were well below normal wave base; such settings would generally have experienced
predominantly unidirectional currents during normal conditions. Calceocrinids could have orien-
tated themselves during growth to the prevailing currents.

Niche position of calceocrinids

Epifaunal suspension-feeding communities commonly have a well-developed vertical niche structure
termed ‘tiering'. The characteristic history of tiering development through the Phanerozoic has been
summarized by Ausich and Bottjer (1982). During the Palaeozoic all tiers contained adult stalked
echinoderms. However, stalked echinoderms (especially crinoids) were responsible for establishing
the higher tier levels throughout the Palaeozoic and part of the Mesozoic. Calceocrinids, recumbent
on the sea floor, deviated from this typical crinoid ecological trend to stand above the bottom.
Calceocrinids and a few other stalked echinoderm groups (Frest and Strimple 1978; Ausich and
Bottjer 1985<7) occupied lower tiers of Palaeozoic communities. Calceocrinids would have been
situated in the 0 to +5 and +5 to -I- 10, 15 or 20 cm tiers of Ausich and Bottjer (1982), or in the
low-level crinoid tier of Ausich (1980).

The ecologic position of calceocrinids in the lower level of diverse, multi-level stalked echinoderm
communities afforded these crinoids an adaptive advantage. Because food resources generally move
horizontally across the sea floor, calceocrinids in low tiers would not have directly competed for
food with most adult crinoids in higher tiers (Lane 1963; Ausich 1980). Competition with other
crinoids would have been reduced for a crinoid in the low tier (Brett 1981). This ecologically
advantageous position may explain in part the temporal success of this family.

DATA FOR DISTRIBUTION TRENDS

Data for this study have been gathered for diversity trends within the Calceocrinidae, generic
diversity of Palaeozoic crinoids, generic diversity of crinoids of the suborder Disparida, and diversity
of the fenestrate bryozoans. These are evaluated at face value, recognizing that some aspects of the
data may reflect the incompleteness of the fossil record.

Species diversity is used to display temporal trends within the Calceocrinidae. All valid cal-
ceocrinid species are included. Species diversity is used for a number of reasons. Twenty-one
calceocrinid genera are recognized, a relatively small number compared with the one hundred and
seven valid species and species-level taxa. The significance of generic diversity trends, as opposed to
species trends, is questioned due to their relatively low value. Additionally, species taxonomy of
calceocrinids has been relatively stable, whereas generic taxonomy and generic assignment of species
have been in a state of flux (Brower 1966, 1977, 1982; Brett 1981; Ausich 1984a). Geographic and
temporal distributions would be less reliable for genera than for species.

Generic diversity of all Palaeozoic crinoids and of disparids is taken uncritically from the Treatise
(Moore and Teichert 1978), with one exception. Until very recently few early Silurian crinoids of

AUSICH: PALAEOZOIC CRINOIDS

89

any kind were known. Descriptions of three new early Silurian crinoid faunas by Witzke and
Strimple (1981), Eckert (1984), and Ausich (1984<r/, b , in prep.) have added many new crinoid
genera and new calceocrinid species. Calceocrinid species from these studies are included in species
distribution trends, so it was considered appropriate to add new early Silurian genera to the Treatise
counts. Few new calceocrinid species have been described from times other than the early Silurian
since the publication of the Treatise. Despite inherent problems with Treatise data sets of this kind,
it is the most comprehensive and current information available.

In the absence of information about fenestrate abundance through time, fenestrate numeric
diversity is used. The term ‘fenestrates’ is used to refer to the reteporiform bryozoans of the Order
Fenestrata (sensu Boardman et al. 1983). Three basic data sets are considered: 1, species nomen-
clatorial diversity of Feneste/la ; 2, generic diversity of fenestrates (Bassler 1953); and 3, generic
diversity of fenestrates from Cuffey and McKinney (1979), Ross (1979, 1981, 1982), and Ross and
Ross (1982). The species nomenclatorial diversity data are from A. S. Horowitz (unpublished
listing). These data include all species names assigned to Fenestella up to 1974. Many of these
species are presently reassigned or synonymized within the Fenestrata. Most early bryozoan taxo-
nomic studies were completed before 1974. Accordingly, this information is used as a relative
index of fenestrate diversity. The Pennsylvanian diversity low is judged to be more an effect of
monographic bias than biotic diversity.

Generic diversity from the Treatise (Bassler 1953) is also used. Included are the Fenestellidae,
Acanthocladiidae, and Phylloporinida, sensu Bassler (1953). Although outdated, Bassler’s com-
pilation remains the last comprehensive summary of fenestrate generic distributions. Subsequent
to Bassler, Cuffey and McKinney (1979) have qualitatively discussed the Devonian history of
fenestrates, and Ross (1979, 1981, 1982) and Ross and Ross (1981) have treated Mississippian,
Pennsylvanian, and Permian fenestrates.

All three sets of fenestrate information agree that diversity increased rapidly during the Devonian
and was relatively high during the remainder of the Palaeozoic.

CALCEOCRINID DISTRIBUTION

Temporal distribution

The family Calceocrinidae is the third most long-ranging crinoid family known (text-fig. 2), existing
for approximately 230 million years from the middle Ordovician (Blackriverian, Llanvirn) into the

text-fig. 2. Histogram of temporal duration in years of crinoid fam-
ilies, as determined from Moore and Teichert (1978) and Harland et
al. (1982). Stippled areas record families with living representatives;
asterisk denotes Calceocrinidae.

90

PALAEONTOLOGY, VOLUME 29

Permian

Pennsylvanian

I

‘ SCALE

5

Species

Mississippian

Devonian

Silurian

Ordovician

CALCEOCRINID SPECIES DIVERSITY

text-fig. 3. Spindle diagram of calceocrinid
species diversity; only valid taxa are in-
cluded.

early Permian (Leonardian, Artinskian). Absolute success of the members of this family varied
tremendously during this time. Text-fig. 3 displays the number of calceocrinid species through time;
the wide diversity fluctuations could call the data into question. No calceocrinids are known from
the late Devonian or from the late Mississippian to the Pennsylvanian, yet numerous and diverse
crinoid communities are known throughout these intervals. The absence of calceocrinids during
certain intervals is considered to be noteworthy rather than totally a consequence of incomplete
data.

The five diversity declines shown on text-fig. 3 consist of: 1, end of the middle Ordovician, with a
diversity increase in the Silurian; 2, end of the Silurian, with subsequent diversity levels never as
high; 3, end of the middle Devonian, with no late Devonian forms but recurrence in the early
Mississippian; 4, end of the early Mississippian, with no later Carboniferous occurrences reported;
and 5, in the early Permian, after which no calceocrinids are known.

Geographic distribution

The first record of the calceocrinids is in the middle Ordovician from North America. By the late
Ordovician calceocrinids were present in both Europe and North America, with genera shared
between continents. Calceocrinids were on both continents with shared taxa through the Silurian,
but they were strictly endemic after the Silurian. The last recorded occurrence of a calceocrinid in
North America is in the early Mississippian; calceocrinids disappeared in Europe after the middle
Devonian, with the exception of Epihalysiocrinus Arendt in the early Permian of the USSR.

Environmental distribution

During the Ordovician and Silurian, calceocrinids were apparently best adapted to shallow-water
carbonate platform settings commonly associated with clastic input. Calceocrinids typically occur
in sequences composed of alternating limestone and shale, such as the middle Ordovician Bromide
Formation (Sprinkle 1982) and late Silurian Brownsport Formation (Amsden 1949). They also
occur in units dominated by carbonates, such as the early Silurian Brassfield Formation, or in units

AUSICH: PALAEOZOIC CRINOIDS

91

dominated by shale, such as the middle Silurian Rochester Shale (Brett, in press). Ordovician and
Silurian calceocrinids probably lived in a range of conditions, as evidenced by variable amounts of
fine elastics, but in general a shallow carbonate setting was typical.

Calceocrinids were present from the Devonian in a wider array of habitats. In addition to
carbonate platform settings, Devonian calceocrinids were more common in clastic settings, such as
the Moscow Shale of New York and the Oriskany Sandstone of Maryland. Mississippian cal-
ceocrinids are present on the Burlington Limestone carbonate ramp in Iowa and in deltaic sediments.
On the Borden delta in Indiana and Kentucky, calceocrinids were present on carbonate banks and
in mudstone and shale facies (Ausich et al. 1979; Kammer et al. 1983).

Lane (1971) recorded an environmental shift in the occurrence of crinoids from the Silurian to
the Devonian. During the middle Silurian camerate crinoids were dominant in both terrigenous
and carbonate settings, whereas by the middle Devonian inadunates dominated in terrigenous areas.
Although calceocrinids remained in Devonian carbonate environments, they paralleled the general
trend of inadunates by their presence in a more diverse array of clastic settings. Calceocrinids are
conspicuously absent after the early Mississippian. Facies populated by pre-early Mississippian
calceocrinids are repeated commonly after this time, and diverse stalked echinoderms are also
common, yet nevertheless, calceocrinids are not reported again until the early Permian.

CALCEOCR1N1D DIVERSITY DECLINES

The search for causes of specific events in evolutionary history is, at best, speculative. Nevertheless
it is an essential step to a fuller understanding of the earth’s biotic history. The a priori assumption
that causes cannot be isolated due to the stochastic nature of evolution or the multiplicity of possible
causes is an unacceptable substitute for a thorough analysis of the palaeoecology and history of a
group under study. Admittedly, a multitude of potential factors may have influenced the group’s
evolutionary history. It is the interaction of these numerous factors which have yielded overall
stochastic evolutionary patterns (e.g. Raup et al. 1973; Raup and Gould 1974). Yet specific evol-
utionary events had specific causes, and these causes should be isolated where possible. Potential
specific causes must be consistent with community ecologic structure, the autecology of the group
studied, the physical environmental setting, and the ecology and history of associated organisms.
The calceocrinid declines could have resulted either from biotic interactions, such as competition
or predation pressure, or from physical environmental changes.

Diversity decreases are considered here in two ways: first, as numeric diversity changes (text-fig.
3); and second, by a comparison of numeric calceocrinid species diversity with total numeric generic
diversity of all crinoids for series throughout the Palaeozoic (text-figs. 4 and 5). This second measure
is a representation of the contribution or relative importance of calceocrinids to all crinoids during
given times. No trend exists among all points plotted in text-fig. 5a (r2 = 0 04). However, two
clusters of points are present, each with a high value of r2. The points in the cluster with the lower
slope are Ordovician to Silurian data, with one exception, and the points in the cluster with the
higher slope are post-Silurian. The one exception is the Late Ordovician which falls in the cluster
of post-Silurian points. Text-figs. 4 and 5 show that calceocrinids played a consistent role during
the Ordovician and Silurian (with the exception of the late Ordovician) but were a much less
important aspect of crinoid faunas after the Silurian. I argue that this shift in the apparent im-
portance of calceocrinids is the most significant calceocrinid diversity change; potential reasons for
this shift will be the primary topic of discussion below.

In addition to the decline after the Silurian, text-figs. 4 and 5 record other fluctuations in
calceocrinid diversity. The first, from middle to Late Ordovician, was both a decline in absolute
diversity and a decline in the relationship between calceocrinids and all crinoids. This decline
accompanied a faunal turnover of all pelmatozoan classes. During the middle Ordovician, pel-
matozoan faunas were characterized by diverse blastozoans and crinozoans. The composition of
Late Ordovician faunas was very different; many blastozoan classes had become extinct, starting a
general decline of blastozoans, and different crinoid groups dominated. These facts notwithstanding.

92

PALAEONTOLOGY, VOLUME 29

CRINOID GENERIC DIVERSITY
VS

CALCEOCRINID SPECIFIC DIVERSITY

SCALE

text-fig. 4. Superimposed histograms of crinoid generic diversity (as
determined from Moore and Teichert 1978) and calceocrinid specific
diversity by series. The comparison of these two data sets is judged to
indicate the relative importance of calceocrinids to crinoid communities

through time.

late Ordovician stalked echinoderms are known from relatively few areas. Assuming that this
indicated Ordovician decline reflects reality, its effect was short lived. By the early Silurian, cal-
ceocrinid species diversity had increased so that its relationship to all crinoids was similar to that of
the Middle Ordovician. This relationship continued throughout the remainder of the Silurian.

Calceocrinids declined again from the late Silurian to the early Devonian, both in numeric
diversity and in relation to all crinoids (text-fig. 4). They never recovered from this decline, and
hypotheses for it will be discussed below. From this position of lesser importance, calceocrinids
experienced three additional declines: 1, they disappeared from the record after the middle
Devonian; 2, after reappearing during the early Mississippian they disappeared from the record
again; and 3, they presumably became extinct after a single showing in the early Permian. Although
the absence of late Devonian calceocrinids is in part an artifact of an incomplete record, the
decline did occur: six calceocrinid genera are recognized in the early Devonian, two are known in
the middle Devonian, while the single Mississippian genus, Halysiocrinus , was also present during
the Devonian. Calceocrinids were endemic from the Devonian to the Permian. By the end of the
Devonian all known European calceocrinids had disappeared, and in North America only Haly-
siocrinus survived. The Mississippian calceocrinid increase records speciation in North America
within Halysiocrinus.

The most intriguing aspect of post-Silurian calceocrinids may not be their occurrences. Rather,
where were they during their absence from the fossil record? From a lessened role, perhaps cal-
ceocrinids shifted after the middle Devonian into facies where their preservational potential was
low. They did expand into a variety of habitats during the early Mississippian, but were excluded
again after the middle Mississippian (after the Osagian-Meramecian crinoid extinction). Their one
Permian record may have been a slight re-expansion into a facies that preserved echinoderms. No
causal hypotheses can be reasonably advanced for the Devonian or Mississippian declines unless
they were the result of the same ecological pressures discussed below for the Silurian-Devonian
decline, but this suggestion cannot be effectively tested. Whether the calceocrinids became extinct
during the early Permian or later with the general Permian extinction of crinoids is not known, and
no testable hypotheses can be offered for the calceocrinid extinction.

Silurian to Devonian decline

I offer two primary hypotheses as potential causes for the Silurian-Devonian decline of the cal-
ceocrinids, arguing more strongly for one; both enlist biotic interaction as the primary factor
influencing the calceocrinid decline. The data perspective employed here seems to rule out physical
environmental causes. No apparent significant environmental change occurred in epicontinental

AUSICH: PALAEOZOIC CRINOIDS

93

Total Calceocrimd Species A Total Calceocrimd Species B

text-fig. 5. Scatter diagrams of crinoid generic diversity versus calceocrinid species diversity, by series.
Same data as presented in text-fig. 4. a, all data; regression line with r 2 = 0 04. b, points below dashed
line from Ordovician and Silurian, points above dashed line post-Silurian; regression line r2 values for
Ordovician and Silurian series are r2 = 0-68 (with lower Ordovician) or r2 = 0-91 (without lower
Ordovician), and for Devonian to Permian series r2 = 0-85; series with no reported calceocrinids are

omitted.

seas from the Silurian to the Devonian and, where present, calceocrinids appear to have been
adapted to a wider array of environmental settings after the Silurian-Devonian decline than
before.

Among biotic interactions that may have affected calceocrinids, pressure from increased predation
and increased competition are suggested. The role of fishes and other durophagous predators
expanded considerably during the Devonian (Signor and Brett 1983, 1984). Laudon ( 1957) suggested
that sharks were important crinoid predators, and Meyer and Ausich (1981, 1983) and Signor and
Brett (1983, 1984) argued that predation pressure has been an important factor in shaping crinoid
evolution. Despite the possible effect of increased predation pressure, it seems unlikely that this
alone could have been primarily responsible for the post-Silurian calceocrinid decline, because of
aspects of calceocrinid autecology and the timing of the durophagous increase.

Kesling and Sigler (1969) suggested that the calceocrinid morphology, close to the substratum,
was an anti-predator adaptation; a closed calceocrinid crown on the sea floor would have been a
less susceptible target for predation. However, when the calceocrinids first appeared in the middle
Ordovician, predation pressures were probably relatively quite low (Brett 1981; Signor and Brett
1984). If calceocrinid design offered anti-predation advantages during the Devonian, it was pre-
adapted for this purpose.

Taxonomic and morphologic changes inferred from increased predation occurred during the
Devonian (Signor and Brett 1984). The abundance of durophagous predators reached a diversity
maximum in the early Mississippian, and inferred responses by their prey are most apparent in the
late Devonian and early Mississippian. The primary decline of calceocrinids took place at or near
the Silurian-Devonian boundary, before the potential effects of increased durophagous pressure
were generally realized, but the decline in calceocrinid numeric diversity by the close of the middle
Devonian is within the time range during which Signor and Brett (1984) concluded that many
groups were adjusting to increased predation pressure. If predation pressure did adversely affect
the fortunes of the calceocrinids, it must have done so in conjunction with other factors.

94

PALAEONTOLOGY, VOLUME 29

The low-level suspension-feeding tier of the calceocrinids was occupied by a variety of inver-
tebrates, including brachiopods, corals, bryozoans, and other crinoids. Although the essence of a
stalked echinoderm is that of an erect organism feeding above the substratum, numerous forms at
many times secondarily assumed a suspension-feeding habit directly adjacent to the substratum
(bottom dwelling) (Frest and Strimple 1978; Ausich and Bottjer 1985a). Ausich and Bottjer (1985a)
surveyed all stalked echinoderms interpreted to have been bottom dwellers; they were relatively
common during the Ordovician, Silurian, Mississippian, and Permian. The only Devonian bottom-
dwelling echinoderms are calceocrinids, the Edriocrinidae (typically confined to high energy facies),
a few diploporite cystoids, and the blastoid Eleutherocrinus. It appears that competition decreased
for calceocrinids from other stalked echinoderms during the Devonian.

The decline of the calceocrinids is independent of a more general, later decline of the inadunate
order Disparida (which includes the Calceocrinidae). When the calceocrinid post-Silurian diversity
decline began, total generic diversity of disparids was increasing towards a middle Devonian high.
Disparid diversity declined after the middle Devonian.

Other low-level, suspension-feeding invertebrates could have been potential competitors. Changes
among brachiopods and molluscs should have had no effect because they probably fed from a level
immediately below calceocrinids, and they most likely ingested a smaller modal food size. Corals
should not have offered a severe competitive threat because, unlike crinoids, they presumably fed
only on live animal tissue in suspension. The increase of diversity and abundance in fenestrate
bryozoans which began in the early Devonian may have had an impact on calceocrinids. Fenestrate
bryozoans were erect suspension feeders, elevated commonly up to 20 cm above the substratum.
Fenestrates and calceocrinids occupied the same ecological space, fed from the same parcels of
water, and were thereby potentially in competition. This second hypothesis appears to be a likely
cause for the post-Silurian calceocrinid decline.

BRYOZOAN REPLACEMENT MODEL

Discussions with other palaeontologists have confirmed my impression from field studies that the
abundance of fenestrate (reteporiform) bryozoans increased substantially during the Devonian, but
data to document this increase in fenestrate abundance are not available. A less precise but never-
theless meaningful alternative to abundance data is fenestrate diversity data; the three data sets
discussed above all agree. A significant increase in fenestrate diversity occurred from the Silurian
to the Devonian. Diversity increased rapidly during the early part of the Devonian and remained
relatively high, with fluctuations, throughout the remainder of the Palaeozoic (text-fig. 6).

By the Mississippian, if not earlier, fenestrates had erect zoaria that were at least 20 cm above the
substratum. From the Devonian, fenestrates occurred typically in densely populated aggregations
(Stratton and Horowitz 1977; Lees 1964; Waters 1977). Fenestrates and calceocrinids must have
occupied the same tier within the ecological structure of epifaunal communities, where they co-
occurred, but they probably fed on different sized particulate food. Assumptions about ingested
food size are based upon size restrictions imposed by the skeleton in areas where food is captured
or ingested and are consistent with aerosol filtration theory (Rubenstein and Koehl 1977; Ausich
1980). Winston (1981) demonstrated that a high correlation exists between mean orifice width and
mouth diameter in living cyclostome and cheilostome bryozoans. She suggested that mean orifice
width could be used to predict mouth diameter in fossil cyclostomes and cheilostomes. Mouth
diameter places an upper limit on the food size of ingested particles (Winston 1981, p. 5). Mean
mouth diameter is approximately 0-23 as large as mean orifice width in cyclostomes and
approximately 0-34 as large in cheilostomes. The width of the ambulacral groove controls the size
of ingested food particles among living crinoids. The minimum food particle dimension can be no
larger than the ambulacral groove width (Rutman and Fishelson 1969).

The relationships of skeletal dimensions of Palaeozoic crinoid adoral groove widths to ambulacral
groove widths, and of fenestrate bryozoan apertures to mouth size are not known, but the
dimensions of the skeletons can be measured to give potential relationships for relative food size

AUSICH: PALAEOZOIC CRINOIDS

95

N=108

(from Bassler, 1953)

20
.t;

<s> ®

Q J 10
9 i
5

c

0) o

UJ 0

OS D M IP P

B

text-fig. 6. Fenestrate bryozoan diversity, a, specific nomenclatorial
diversity of Fenestella; most taxa are reassigned to other fenestrate gen-
era (data compiled by A. S. Horowitz and include species named up to
1974). b, generic diversity of fenestrate bryozoans (Fenestellidae, Acan-
thocladiidae, and Phylloporinidae; data from Bassler (1953).

table 1. Statistics for early Carboniferous fenestrate bryozoan apertures. The maximum aperture diameter
is given, thereby providing the largest measure possible. All measurements are from specimens at a single
locality from a limited stratigraphic interval. The calceocrinid Halysiocrinus tunicatus (Hall) is present in this
fauna. Lower Carboniferous (lower Mississippian), Edwardsville Formation, Indiana University locality
number 15109 (see Ausich 1983). X, mean; SD, standard deviation; N, number of measurements; measure-
ments in mm.

Taxon

Maximum aperture

diameter

X

SD

N

Fenestella spp.

012

002

48

Penniretepora spp.

Oil

004

100

Polypora spp.

010

002

30

Thamniscus spp.

0 16

004

63

differences. Comparisons are made from an early Carboniferous example where fenestrates and a
calceocrinid do co-occur (Table 1 ). Measurements are from specimens from a single locality (Indiana
University locality 15109) in the Edwardsville Formation of Indiana (Ausich 1983). Four genera of
fenestrates and one species of calceocrinid, Halysiocrinus tunicatus (Hall) are considered. The mean
maximum aperture diameter of fenestrates varies from 010 to 016 mm (to be conservative the
largest dimension was measured rather than aperture width). A single specimen of H. tunicatus is
preserved such that the adoral groove width of food gathering branches can be measured as 0-65
mm (Ausich 1980). Acknowledging all the potential problems of soft part dimensions and adherence
to modern analogues, the measured skeletal dimensions that were probably related to controls on
food size were different in early Carboniferous fenestrates and calceocrinids: adoral groove widths
in calceocrinids ranged from 4- 1 to 6-5 times larger than the maximum aperture widths of fenestrate
bryozoans. It follows that fenestrates may have been restricted to food particles smaller than those
available to calceocrinids. Therefore, even though they occupied the same ecologic space, they may
not have directly competed for the same food resources.

96

PALAEONTOLOGY, VOLUME 29

Despite this potential lack of direct competition for food, fenestrates and calceocrinids probably
did compete. Dense aggregations of fenestrates would have precluded the establishment of a cal-
ceocrinid with its column extended along the bottom; the current baffling ability of a dense fenestrate
aggregation could have created a very low current setting at the substratum; and the relatively
larger food size captured by calceocrinids (Ausich 1980) would probably have been carried by
stronger currents than may have been present within dense fenestrate aggregations. This habitat
modification could have adversely affected calceocrinid survival. Also, in ‘head-to-head’ competition
for substratum space and for space within lower tiers, calceocrinids would most probably have lost
by virtue of the generally slower growth rate of solitary as opposed to colonial organisms (Jackson
1977).

DISCUSSION

The considerable temporal success of the Calceocrinidae was blemished by sharply diminished
diversity and abundance after the Silurian. Two biotic changes, concurrent with the calceocrinid
decline, are isolated as potential causes: an increase in predation pressure and an increase in
competition by fenestrate bryozoans. Both causes are reasonable with what is generally understood
about the palaeoecology of Palaeozoic crinoids. Nevertheless, it is judged that effects from com-
petition with fenestrate bryozoans have a more significant impact on calceocrinids. The mere
correlation of the calceocrinid decline with the rise in fenestrates does not prove a causal link, but
it is consistent with the palaeoecology of calceocrinids that fenestrates could have severely restricted
calceocrinid success. The decline of the calceocrinids in the early Devonian is considered to represent
an example of partial ecologic replacement of calceocrinids by fenestrate bryozoans. A test of the
fenestrate hypothesis would be a comprehensive palaeoecologic analysis of post-Silurian communi-
ties with and without calceocrinids. Such an analysis is beyond the scope of the present study,
but an initial survey suggests that, with rare exception, post-Silurian calceocrinids were most
successful in settings with low fenestrate abundance.

An important implication of this study is that ecologic processes probably had a strong impact
on the evolutionary history of the Calceocrinidae. This counters ideas that ecologic processes cannot
have an important impact in evolutionary time. Ausich and Bottjer (1985a) argued that there is no
a priori reason to discount the additive evolutionary potential of such processes; Meyer and Ausich
(1983) and Ausich and Bottjer (1985a) also argued for a strong ecologic impact on the evolution of
the Crinoidea.

This study may also support the component concept of community palaeoecology (Ausich 1983).
Ausich argued that communities could be subdivided into trophic/taxonomic groups termed ‘com-
ponents’. Each component responded to different physical environmental pressures, thereby having
independent distributions. Evolution should be sensitive to components, and readjustments of taxa
through time should take place within components. The diversification of fenestrates resulted in a
readjustment within the component of organisms limited by conditions at the sediment-water
interface ( sensu Ausich 1983).

Acknowledgements. A. S. Horowitz and R. J. Cuffey provided information on fenestrate bryozoan diversity.
Discussions with D. B. Blake, A. S. Horowitz, and R. J. Cuffey were very useful. N. G. Lane, A. S. Horowitz,
and two anonymous reviewers improved earlier drafts of this study. Helen Jones typed the manuscript.
Acknowledgement is made to the Donors of the Petroleum Research Fund, administered by the American
Chemical Society, for partial support of this research.

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1983. Biotic interactions among recent and among fossil crinoids. Pp. 377-427. In tevesz, m. and
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1 -40.

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ramsbottom, w. h. c. 1952. Calceocrinidae from the Wenlock Limestone of Dudley. Bull. geol. Surv. Gt Br.
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-schopf, T. j. m. and simberloff, d. s. 1973. Stochastic models of phytogeny and the evolution of
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winston, J. E. 1981. Feeding behavior of modern bryozoans. In broadhead, t. w. (ed.). Lophophorates.

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Typescript received 3 January 1985
Revised typescript received 15 April 1985

WILLIAM I. AUSICH

Department of Geology and Mineralogy
125 South Oval Mall

The Ohio State University
Columbus, Ohio 43210-1398
USA

SOLAR CYCLICITY IN THE PRECAMBRIAN
MICROFOSSIL RECORD

by ZHANG ZHONGYING

Abstract. The first detailed investigation of a probable noctidiurnal growth rhythm of the tubular
oscillatoriacean cyanophyte Siphonophycus inornatum Y. Zhang, in stratiform stromatolites of the mid-
Proterozoic Gaoyuzhuang Formation (c. 1400 1500 ma), Hebei Province, North China, is presented herein.
The sequence consists of light, thick, silica-filled layers alternating with dark, thinner, algal-rich layers. The
filaments exhibit a distinct, layered pattern of horizontally orientated populations alternating with vertically
orientated populations. The light layers are composed of erect filaments and are interpreted as recording
phototactic, daytime algal growth; the dark layers are composed of prostrate filaments and reflect nocturnal
growth. This layered, cryptalgal microfabric is quite similar to the noctidiurnal growth patterns of Phormidium
hendersonii Howe filaments in modern stromatolites from the Caribbean area. In favourable conditions the daily
increments recorded by fossil biolamination doublets reached as high as 600 700 ^m. Such biolamination
confirms a solar cyclicity 1400-1500 ma ago.

Stromatolites, both fossil and Recent, are interpreted by most workers as organosedimentary
structures produced by sediment trapping, binding, and/or precipitation resulting from metabolic
activity and growth of organisms, primarily blue-green algae (Awramik el al. 1976). Recent
stromatolites have been described from several areas of modern carbonate sedimentation, including
Shark Bay, Western Australia, the Persian Gulf, the Bahamas, Bermuda, and the Great Salt Lake,
Utah. Fossil stromatolites were widespread, particularly in the Precambrian, and reached a high
abundance and diversity by mid- to late Precambrian. They have been used for environmental and
palaeoecological analyses, and for time-stratigraphic correlation of ancient sediments. To assess the
usefulness of stromatolites, however, it is essential to determine the potential effect of both
environmental and microbial factors on stromatolite growth. Studies of the microbiology and
morphogenesis of Recent stromatolites provide a basis for the interpretation of Precambrian
stromatolites. Such comparisons are especially valuable in deciphering the mode of formation of
Precambrian stromatolites.

In 1983 I made a reconnaissance of the c. 1400-1500 ma old Gaoyuzhuang Formation
(Changchengian System) of Pangjiabu, Zhangjiakou, Hebei Province, North China (text-fig. 1 ); rock
samples were collected from black cherts of stratiform stromatolites at different horizons within the
formation. A preliminary note (Zhang and Li 1984) reported the discovery of a probable noctidiurnal
growth rhythm of a filamentous cyanophyte, using petrographic thin sections cut perpendicular to
the lamination. This paper formally describes and illustrates the rhythmic growth, movement, and
particle-trapping behaviour of the micro-organism that built the stromatolites. Their potential
significance as environmental and palaeoecological indicators is also discussed.

GEOLOGICAL SETTING AND AGE

The Precambrian geology and stratigraphy of the Western Yanshan Range, Hebei Province, have
been discussed in detail by Du and Li (1980). In the Pangjiabu region, about 1 15 km north-west of
Beijing (Peking), Hebei Province, a 1500 m thick section of essentially unmetamorphosed
Changchengian (mid-Proterozoic) sedimentary rocks is well exposed (text-figs. 1 and 2). The
Changchengian System rests unconformably upon the Archaean Qianxi Group (dated as over 3000
ma to c. 3600 ma by K-Ar, Rb-Sr isochron, and U-Pb isochron determinations: Cheng et al. 1982)

IPalaeonlology, Vol. 29, Part 1, 1986, pp. 101-111, pi. 17.]

102

PALAEONTOLOGY, VOLUME 29

1

2Z2

-L-

4 5 6 7 8 9 10 11

text-fig. 1. Location and geological map of the Pangjiabu region, Hebei Province, north China. Key:
1 , Quaternary; 2, Jurassic; 3, Wumishan Formation; 4, Gaoyuzhuang Formation; 5, Dahongyu and Tuanshanzi
Formations; 6, Chuanlinggou Formation; 7, Changzhougou Formation; 8, Archaean (Qianxi Group);
9, Mesozoic granite; 10, orthoclase porphyry; 1 1, section, summarized in text-fig. 2.

and paraconformably underlies the Wumishan Formation (Jixianian System). The Qianxi Group
is composed mainly of granulites, gneisses, and plagioclase-amphibolites. The Wumishan Formation
is comprised of cherty dolomites and is the only formation of the Jixianian System which outcrops in
this region. The Changchengian System is well developed here, and has been subdivided by many
geologists into the five formations described in text-fig. 2.

Radiometric dates for various units of the Changchengian System in the Yanshan Range, North
China, have been obtained by the Laboratory of Isotope Geology, Kweiyang Institute of

PROTEROZOIC

Changchengian Jixianian

ZHANG: PRECAMBRIAN MICROFOSSILS

103

System Member

Formation

Gaoyuzhuang Formation (up to 1018 m). Intertidal
and subtidal carbonates, mainly grey and dark grey
cherty dolomites and stromatolitic dolomites, and
minor manganiferous dolomites, siltstones, and silty
shales. The formation can be subdivided into six
members. Most of the well-preserved spheroidal and
filamentous microfossils are found in the black cherts
of stromatolitic dolomites which occur in the second
member, 100 198 m from the base of the formation
(Zhang and Li 1985).

Daliongyu Formation (112 m). Shallow-water,
quartzose sandstones, arkosic sandstones, and sandy
dolomites, with some brilliant green, K-rich shales.

Tuanshanzi Formation (167 m). Subtidal to
supratidal, argillaceous and ferruginous dolomites,
sandy dolomites, and dolomitic siltstones and sand-
stones, with halite casts and stromatolites in
upper part.

Chuanlinggou Formation (62 m). Intertidal and
subtidal, black and greyish-green silty shales and
shales interbedded with siltstones and fine-grained
sandstones, with some hematitic iron beds in lower
part. The reniform iron ore consists of varied forms of
stromatolites (Zhu 1980). Some sphaeromorphic
acritarchs have recently been recovered from the
shales.

Changzhougou Formation (c. 174m). Shallow-water,
intertidal and subtidal, white quartzose sandstones,
arenaceous shales, and black shales.

text-fig. 2. Generalized lithostratigraphic column for section a-b in text-fig. I, Pangjiabu region, Hebei
Province, north China. The arrow indicates the fossiliferous horizon studied.

104

PALAEONTOLOGY, VOLUME 29

Geochemistry, Academia Sinica (1977) and the Tianjin Institute of Geology and Mineral Resources
(Chen et al. 1980). Shale from the Chuanlinggou Formation has yielded a whole-rock Pb-Pb
isochron age of 1922 ma, and a U-Pb model age of 1910 ma, while an intrusive porphyritic dyke has
yielded phlogopite K-Ar ages of 1817 and 1875 ma. The overlying Tuanshanzi and Dahongyu
Formations were dated at 1776 ma (whole-rock U-Pb isochron age), and 1678, 1643, and 1621 ma
(K-Ar ages, AK = 0-585 x 10 10a J) respectively. Galena from the Gaoyuzhuang Formation gave
whole-rock Pb-Pb isochron ages of 1384, 1434, and 1485 ma. These age determinations indicate that
the base of the Changchengian System is approximately 1950 ma and the upper limit of the system is
about 1400 ma; these figures have been accepted by most Chinese geologists. The available data,
therefore, suggests an age of 1400-1500 ma for the fossiliferous stromatolitic cherts from the
Gaoyuzhuang Formation.

MATERIAL AND METHODS

The material studied comes from the top of the second member of the Gaoyuzhuang Formation, 1 64-6- 183-6 m
above its base. The unit consists of thin-bedded to medium-bedded, grey and dark grey argillaceous dolomites,
cherty dolomites, and stromatolitic dolomites, with some siltstones and silty shales. Well-preserved filamentous
and coccoid microfossils are found in black cherts which occur as stromatolitic layers, bands, lenses, or as
nodules in dolomites. It is evident that abundant, amorphous organic matter, finely disseminated throughout the
silica matrix, makes the chert dark or black in hand specimen. The chert is aphanitic and composed of
chalcedony and microcrystalline quartz.

Petrographic thin sections were studied by transmitted light microscopy; most were cut strictly perpendicular
to the lamination and 30 )jm thick (some thicker sections were cut to avoid damaging the microfossils). The thin
sections show the microfossils to be indigenous to the rock, and to have been buried in the surrounding silica
matrix during their growth and decay. Some selected rock samples were treated using standard palynological
techniques for comparative study.

NOCTID1URNAL ALGAL GROWTH RHYTHM

Microfabric

The chert layers and lenses preserve a characteristic wave planar microfabric in the stratiform
stromatolites. Vertical sections reveal a prominent fine lamination of light, thick, silica-filled layers,
generally 350-500 (range 150-600) pm thick, alternating with dark, thinner, algal-rich layers,
generally 20-30 (up to 100) pm thick (PI. 17; text-figs. 3 and 4A-c).The stratiform stromatolites yield
abundant filamentous microfossils which are so well preserved that the relationship between micro-
organisms and microfabric is revealed. The presence of micro-organisms within a Recent or fossil
stromatolite does not necessarily imply any causal relationship with the genesis of the structure
(Hofmann 1973), but the filaments described here undoubtedly played an important role in building
the microfabric of the stromatolites.

The light layers are composed of anastomosing bundles of filaments, erect or inclined at various
angles, which form a three-dimensional reticulated framework. It appears that the filaments are

EXPLANATION OF PLATE 17

Figs. 1 3. Siphonophycus inornatum Y. Zhang. A probable noctidiurnal growth rhythm of the tubular
oscillatoriacean cyanophyte, in stratiform stromatolites of the mid-Proterozoic Gaoyuzhuang Formation,
Hebei Province, North China. The thin sections were cut perpendicular to the lamination. 1, Nanjing
University Palaeobotanical Collection B8414 (thin section PG79-002), well-preserved biolamination
doublets, showing an alternating noctidiurnal sequence of at least four days; each light, thick, silica-filled layer
with vertical filaments was formed during daylight, while each dark, thinner, algal-rich layer with horizontal
filaments was formed at night, x 1 10. 2, NUPC B8410 (thin section PG79-001), part of text-fig. 4a, showing
detail of prostrate filaments in dark layer, x 800. 3, detail of fig. 1 (arrow), showing transition between day and
night-time filament arrangements, x 400.

PLATE 17

ZHANG, Siphonophycus

106

PALAEONTOLOGY, VOLUME 29

text-fig. 3. Probable noctidiurnal growth rhythm of the tubular
oscillatoriacean cyanophyte Siphonophycus inornatum Y. Zhang, in
stratiform stromatolites of the mid-Proterozoic Gaoyuzhuang
Formation, Hebei Province, north China. The vertical section
shows a noctidiurnal sequence of two days. The light layer (A) is
composed of erect filaments which trapped detrital carbonate
grains (g) and records phototactic daytime algal growth. The dark
layer (B) is composed of prostrate filaments and was formed
at night.

preserved close to their life position since, without mineral support, compaction would have altered
their vertical orientation. It thus appears that, in these specific layers, the filaments were supported by
a silica matrix during the early stages of diagenesis.

The dark layers consist of prostrate filaments which fuse laterally, are closely crowded into a thin
opaque partition, and form a planar reticulated framework. Some of these layers may be completely
organic but others often include detrital carbonate particles. At the top of each dark layer the
filaments change their growth pattern, turning upwards to assume a vertical position (perpendicular
to the lamination) in the overlying light layer before returning to a bedding-parallel orientation again
in the next dark layer (PI. 17, fig. 3; text-fig. 3).

Palaeontology

A notable biological feature of the lamination is that almost monospecific populations, assignable to
the tubular oscillatoriacean cyanophyte Siphonophycus inornatum Y. Zhang, contribute to micro-
fabric formation. These filamentous algal mats are three-dimensionally preserved in situ and their
spatial relationships are clearly retained. Not only are the filaments characteristically interwoven
along the bedding, but they also exhibit a distinct pattern of horizontally and vertically oriented
populations in alternating layers. It is apparent that most Gaoyuzhuang stratiform stromatolites are
demonstrably of algal origin; the filaments that built them were also recovered from macerations.

Schopf (1968) erected the genus Siphonophycus for large, empty sheaths of the Oscillatoriaceae.
There are no distinct morphological differences between Siphonophycus Schopf and Eomycetopsis
Schopf, emend. Knoll and Golubic, 1979, except size. I have recently emended the former genus, and
proposed a size limit of not more than 5 ^m for average filament diameter to differentiate the two
genera (Zhang Zhongying, in press). It should be noted that numerous genera and species are capable
of producing extracellular sheaths that, in the fossil record, would be grouped together in the same
form genus Siphonophycus (see Knoll 1984).

S. inornatum was first described by Zhang Yun (1981) from the same formation (but not the same
horizon) and locality as the present material. Filaments of S. inornatum are non-septate, unbranched,
and tubular, 2-4-8 0 in diameter (x = 5-1 p.m; N = 173) and up to 950 long, with a wall
thickness of c. 0-5 - 1 -0 /mi, and a surface texture which is generally smooth but granulate in degraded
filaments. This microfossil may represent the external polysaccharide sheaths of Lyngbya /
Phormidium- type blue-greens. As most filaments in the microfabric consist of empty sheaths only, it is
reasonable to assume that the trichomes of this micro-organism had a significant gliding motility
(trichomes glide out of their sheaths and subsequently produce new sheaths). Some tubular sheaths
containing a single degraded trichome were found in the present material.

ZHANG: PRECAMBRIAN MICROFOSSILS

107

The mats of S. inornatum also contain coccoids: Palaeoanacystis Schopf, 1968, Nanococcus
Oehler, 1977, Myxococcoides Schopf, 1968, Sphaerophycus Schopf, 1968, and others. Some occur as
local populations on a bedding plane, suggesting that they may have been mat dwellers. Others occur
as individuals or aggregates more or less randomly distributed throughout the thin section; these may
represent allochthonous elements that lived in the water column above the accreting mats.

Modern counterpart and interpretation

Extant, non-lithified, finely laminated stromatolitic domes have been repeatedly reported from the
western Atlantic ocean and the Caribbean sea (Ginsburg and Lowenstam 1958; Monty 1965, 1967,
1976; Gebelein 1969; Golubicand Focke 1978). Their formation was originally attributed to different
micro-organisms: Symploca laete-viridis Gomont (Ginsburg and Lowenstam 1958), Schizothrix
calcicola (Agardh) (Monty 1965, 1967; Gebelein 1969), and Schizothrix sp. (Golubic 1973). Later,
their high degree of similarity and overlap in morphometric properties led Golubic and Focke ( 1 978)
to conclude that these micro-organisms all belonged to the same microbial species, now classified as
Phormidium hendersonii Howe. This species is motile and characterized by daily movements in
accordance with diurnal light variation. Such phototactic movement and subsequent production of a
common hard gel can induce an alternate arrangement of vertical and horizontal filaments which,
together with entrapped sedimentary particles, produces a primary noctidiurnal lamination. During
the day, cell division and vertical movement of the trichome within the ever elongating sheaths are
dominant, producing a thick hyaline layer up to 900 p.m thick; at night, filaments grow prostrate and
at a much slower rate, forming a thin dark layer up to 1 00 thick (Monty 1 967, 1 976). The gliding
motility of its trichomes ensures that 90% of P. hendersonii filaments in the interior of stromatolitic
domes consist of empty sheaths only (Golubic and Focke 1978).

Similar phototactic responses have also been observed in modern siliceous fiat-topped stroma-
tolites built by P. tenue var. granuliferum Copeland in Yellowstone National Park (Walter et al.
1976). Doemel and Brock (1974) reported extant stromatolites built by the photosynthetic
filamentous bacterium Chloroflexus, in which the bacterium migrates upward at night and grows
horizontally during the day— the opposite of Phormidium.

Comparison of the stratiform stromatolites from the Gaoyuzhuang Formation (produced by
S. inornatum mats) with the modern stromatolitic domes from the Caribbean area (produced by
P. hendersonii mats) demonstrates a great similarity in their microfabric, despite being separated in
time by c. 1400- 1 500 ma. Based on its modern counterpart, text-fig. 3 illustrates the possible growth
dynamics of S. inornatum. One complete lamination of S. inornatum is composed of a light,
thick, silica-filled layer capped by a dark, thinner, algal-rich layer; each lamination is interpreted as
having formed in one day (reflecting a diurnal cyclicity in algal growth, orientation, and movement),
the light layers during daylight and the dark layers at night. The daily growth recorded by one
lamination was locally as much as 600-700 pm.

During daylight the gliding trichomes of S. inornatum moved upward phototactically. They were
supported by their sheaths and by bundling of filaments, leading to the formation of a thick layer of
erect filaments up to 600 ^m thick. A site of some minor relief was probably required for the initiation
of algal growth. Under favourable conditions and particularly at a low, more or less constant rate of
sedimentation, the rapidly growing mat during daylight would have incorporated sedimentary
detrital carbonate as scattered particles in a distinctly hyaline (light), relatively sediment-poor layer
(text-fig. 4c). At night, in contrast, S. inornatum grew slowly and horizontally to form a thinner,
algal-rich (dark) layer made of prostrate filaments. The dark layer is usually only 0T-0T3 times as
thick as the light layer. If sedimentary particles continued to be incorporated at the same rate, the
density of particles accumulated during the night within the dark layer would have been 8 10 times
higher, and the dark layer would have become easily loaded to capacity with detritus. The overnight
prostrate sheets developed even when sedimentation ceased altogether; in this case they appear in
thin section as a thin, dark line. With the resumption of growth the following day the trichomes must
have glided out of their sheaths, turned upwards to a vertical orientation (perpendicular to the
bedding), and trapped sedimentary grains, thereby producing a new light layer.

108

PALAEONTOLOGY, VOLUME 29

C D

text-fig. 4. A laminated organosedimentary structure produced by the tubular oscillatoriacean cyanophyte
Siphonophycus inornatum Y. Zhang, in stratiform stromatolites of the mid-Proterozoic Gaoyuzhuang
Formation, Hebei Province, north China. Bar scale is 100 long; all vertical thin sections, a, c, Nanjing
University Palaeobotanical Collection B8410 (thin section PG79-001); b, NUPC B8412 (thin section PG79-076);
d, NUPC B8414 (thin section PG79-002). a, b, horizontally and vertically orientated filaments in alternating
layers; the light layers are composed of erect filaments and interpreted as recording phototactic daytime algal
growth, whereas the dark ones are composed of prostrate filaments and reflect nocturnal growth, c, part of light
layer in a, showing entrapped detrital carbonate grains (g). d, light layer (about 4 mm below PI. 17, fig. 1)
swamped by intensive sedimentation; basic biolamination no longer distinct, and a massive boundstone

(b) was formed.

DISCUSSION AND SUMMARY

Students of ancient stromatolites have fallen into two broad ‘schools’ during the last thirty years: the
‘biostratigraphical school’ considers fossil stromatolites to be biogenic entities, many of which have
been used as time-stratigraphical tools; the ‘palaeoecological school’ considers fossil stromatolites to
be sensitive environmental indicators. Recent studies of the microbial composition of modern

ZHANG: PRECAMBRIAN MICROFOSSILS

109

algal mats call for a more integrated approach, taking both biotic and environmental interpretations
into consideration. According to Golubic and Focke (1978), populations of a single algal species
living under different conditions (ranging from subtidal to intertidal) always produce remarkably
similar stromatolites. Sedimentological studies indicate that the Gaoyuzhuang Formation consists
mainly of cherty dolomites and stromatolitic dolomites formed in intertidal and subtidal
environments. The associated stratiform stromatolites are laminated organosedimentary structures
produced by the active, tubular oscillatoriacean form taxon S. inornatum , thus supporting the
interpretation of biological control for stromatolites, irrespective of differences in environmental
conditions within the range of their distribution. Flowever, the optimum habitat for S. inornatum
mats may have been shallow, intertidal, hypersaline lagoons in a warm climate, with some aerial
exposure during the tidal cycle.

Diurnal light variation appears to have been responsible for the microfabric of the S. inornatum
mats described above. These mats retain within their microfabric a record of rhythmic growth, move-
ment, and the particle-trapping behaviour of the filaments that built the stratiform stromatolites. The
distinctive orientation of S. inornatum filaments also demonstrates that, at least in some areas of the
mid-Proterozoic Gaoyuzhuang Sea, the sheaths of S. inornatum were autochthonous; thus, this
micro-organism occurred as a primary mat builder. The evidence suggests that the biolaminations
built by S. inornatum record a probable solar cyclicity 1400-1500 ma ago. This kind of noctidiurnal
rhythm in the orientation and growth dynamics of algal filaments must have existed in the early
history of the Earth, and similar microfabrics are to be expected in other Precambrian stromatolites.
Knoll (1981 ) mentioned that some Eomycetopsis robusta mats preserved in silicified, flat-laminated,
microbial stromatolites from the Ross River (late Precambrian, c. 740-950 ma) occasionally display
a distinct microfabric in which members of the population are orientated parallel to the bedding
plane in one lamina, turn upward to a vertical position in the overlying band, and then return to
a bedding-parallel orientation. This example probably represents a phototactic response by the
micro-organism involved.

‘Ideal' biolamination doublets are not always well developed. Often the doublets appear in thin
sections to be somewhat erratic and incomplete. Since the biolamination originated from the
combined effects of algal growth and sedimentation, its development depended on a harmonious
balance between the algal growth rate and the quantity of available sedimentary particles: at high
sedimentation rates the biolamination was obliterated by oversedimentation and a massive
boundstone was formed (text-fig. 4d); where sediment supply was low or zero the growth of a purely
algal mat prevented biolamination. The rates of both processes vary through time and space, not only
between different algal populations, but also between different portions of one population, making
the resulting biolamination more complex.

Several biological, geochemical, physical, and sedimentological factors can influence algal growth
and sedimentation rate, e.g. invasion of the mats by other micro-organisms, changes in intensity of
incident sunlight, the destructive effects of strong wave surge, heavy rain, and swift currents, the
slowing down of algal growth rate during periods of drought or when higher salinities prevailed, and
the destruction of laminations by abrasion in areas of very rapid sediment movement. From
observations on the algal growth of Recent stromatolites (Monty 1967, 1976; Walter et al. 1976), it
can be predicted that S. inornatum had periods of rapid algal growth, periods when it slowed down,
and even periods when the mats stopped growing for several days, during which time nothing was
added to the biolamination.

Post-depositional changes must also be considered. Prior to silicification, the algal mats would
have undergone structural degradation, compaction, and diagenetic destruction, thereby obscuring
the biolamination and altering the vertical orientation pattern of the component filaments.
A biolamination is only well-preserved in zones where silicification took place during the early stages
of diagenesis.

A continuous sequence of several tens of biolamination doublets has not been found in thin
sections of the present material, for reasons outlined above. It is therefore impossible to determine the
complete age of the algal microfabric by counting biolamination doublets in thin sections. Such

110 PALAEONTOLOGY, VOLUME 29

doublets, however, strongly favour the existence of an ancient noctidiurnal growth rhythm in
S. inornatum.

Acknowledgements . I am grateful to the Department of Geology, Nanjing University, Nanjing, People’s
Republic of China for supporting this research, and to Professor Du Rulin and Mr Tian Lifu (Hebei College of
Geology) for guiding me in the held.

REFERENCES

awramik, s. m., margulis, l. and barghoorn, e. s. 1976. Evolutionary processes in the formation of
stromatolites. In Walter, m. r. (ed.). Stromatolites. Developments in sediment ology, 20, 149 162. Elsevier,
Amsterdam, Oxford and New York.

chen jinbiao, zhang huimin, zhu shixing, zhao zhen and wang ZHENGANG. 1980. Research on Sinian
Suberathem of Jixian, Tianjin. In tianjin institute of geology and mineral resources, Chinese academy
of geological sciences (ed.). Research on Precambrian geology , Sinian Suberathem in China , 56-1 14. Tianjin
Science and Technology Press, Tianjin. [In Chinese, with English abstract.]
cheng yugi, bai jin and sun dazhong. 1982. The Lower and Middle Precambrian of China. In Chinese
academy OF geological sciences (ed.). Stratigraphy of China , No. 1: An outline of the stratigraphy of China ,

1 46. Geological Publishing House, Beijing. [In Chinese, with English abstract.]
doemel, w. n. and brock, t. d. 1974. Bacterial stromatolites: origin of laminations. Science , 184, 1083 1085.
du rulin and li peiju. 1980. Sinian Suberathem in the western Yanshan Ranges. In tianjin institute of
geology and mineral resources, Chinese academy of geological sciences (ed.). Research on Precambrian
geology , Sinian Suberathem in China , 341-357. Tianjin Science and Technology Press, Tianjin. [In Chinese,
with English abstract.]

gebelein, c. d. 1969. Distribution, morphology, and accretion rate of Recent subtidal algal stromatolites,
Bermuda. J. sedim. Petrol. 39, 49-69.

ginsburg, r. n. and lowenstam, h. a. 1958. The influence of marine bottom communities on the depositional
environment of sediments. J. Geol. 66, 310-318.

golubic, s. 1973. The relationship between blue-green algae and carbonate deposits. In carr, n. g. and
whitton, b. a. (eds.). The biology of blue-green algae , 434 472. Blackwell Scientific, Oxford.

— and focke, j. w. 1978. Phormidium hendersonii Howe, identity and significance of a modern stromatolite
building microorganism. J. sedim. Petrol. 48, 751-764.
hofmann, h. j. 1973. Stromatolites: characteristics and utility. Earth Sci. Rev. 9, 339-373.
knoll, a. h. 1981. Paleoecology of late Precambrian microbial assemblages. In niklas, k. (ed.). Paleobotany,
paleoecology, and evolution, Vol. 1, 17-54. Praeger, New York.

1984. Microbiotas of the Late Precambrian Hunnberg Formation, Nordaustlandet, Svalbard. J. Paleont.
58, 131-162.

-and golubic, s. 1979. Anatomy and taphonomy of a Precambrian algal stromatolite. Precamb. Res.
10,115-151.

LABORATORY OF ISOTOPE GEOLOGY, KWEIYANG INSTITUTE OF GEOCHEMISTRY, ACADEMIA SINICA. 1977. On the Sinian
geochronological scale of China based on isotopic ages for the Sinian strata in the Yanshan region. North
China. Scientia sin. 20, 818-834.

monty, c. L. v. 1965. Recent algal stromatolites in the Windward Lagoon, Andros Island, Bahamas. Annls Soc.
geol. Belg. 88, 269-276.

— 1967. Distribution and structure of Recent stromatolitic algal mats, Eastern Andros Island, Bahamas. Ibid.
90, 55 -100.

— 1976. The origin and development of cryptalgal fabrics. In Walter, m. r. (ed.). Stromatolites. Developments
in sediment ology, 20, 193-249. Elsevier, Amsterdam, Oxford and New York.

oehler, j. h. 1977. Microflora of the H.Y.C. Pyritic Shale Member of the Barney Creek Formation (McArthur
Group), middle Proterozoic of northern Australia. Alcheringa, 1, 315-349.
schopf, j. w. 1968. Microflora of the Bitter Springs Formation, late Precambrian, central Australia. J. Paleont.
42, 651-688.

Walter, M. r., bauld, j. and brock, T. D. 1976. Microbiology and morphogenesis of columnar stromatolites
( Conophyton , Vacerrilla) from hot springs in Yellowstone National Park. In Walter, m. r. (ed.).
Stromatolites. Developments in sedimentology , 20, 273-310. Elsevier, Amsterdam, Oxford and New York.

ZHANG: PRECAMBRIAN MICROFOSSILS

zhang yun. 1981. Proterozoic stromatolite microfloras of the Gaoyuzhuang Formation (early Sinian:
Riphean), Hebei, China. J. Paleont. 55, 485-506.

zhang zhongying (in press). New material of filamentous cyanophytes from the Doushantuo Formation (Late
Sinian) in the Eastern Yangtze Gorge. Scientia Geol. sin. [In Chinese, with English abstract.]

and li ZHENGHUi. 1984. Noctidiurnal growth rhythm of filamentous cyanophytes from the Gaoyuzhuang
Formation (Changchengian System) of North China. Kexue Tongbao (5c/.), 29, 1132-1 133.

1985. Microflora of the Gaoyuzhuang Formation (Changchengian System) of the western Yanshan
Range, North China. Acta micropalaeont. sin. 2, 219-230. [In Chinese, with English abstract.]
zhu shixing. 1980. Iron stromatolites in Xuanhua-Longguan area of Hebei Province and its significance. Bn//.
Chin. Acad. Geol. Sci. ser. 6, 1, 70-90. [In Chinese, with English abstract.]

Typescript received 26 October 1984
Revised typescript received 13 June 1985

zhang zhongying
Department of Geology
Nanjing University
Nanjing

People’s Republic of China

A REVIEW OF ANTARCTIC ICHTHYOFAUNAS
IN THE LIGHT OF NEW FOSSIL DISCOVERIES

by LANCE GRANDE and JOSEPH T. EASTMAN

Abstract. The fossil and Recent fish fauna of the Antarctic region is systematically and biogeographically
reviewed. The occurrence of Pristiophoridae, Chimaeriformes, and Siluriformes is reported from the Antarctic
region for the first time. The pristiophorids, chimaeriformes, and previously reported Antarctic shark fossils
show that although chondrichthyans are a minor component of the Recent Antarctic fauna, they are very diverse
in the Lower Tertiary fossil record of the continent. The occurrence of a catfish in Antarctica shows that
Siluriformes have been present on all continents of the Southern Hemisphere. The Palaeozoic and early
Mesozoic fishes indicate primarily an Australian biogeographic affinity for Antarctica, reflecting the proximity
of the two continents to each other during those times. The more recent ichthyofaunas show no particular
biogeographic affinity.

Fossil fishes from Antarctica are of particular interest to biogeographers because of the lack of
diversity in the Recent Antarctic fauna. Biogeographic (area) relationships are usually determined on
the basis of relationships of taxa (Nelson and Platnick 1980, 1981; Grande 1985). Areas with
relatively few taxa, in general, provide less biogeographic data than areas with many taxa. There are
only eighteen families of Recent fishes in the Antarctic region (DeWitt 1971), with most of the species
belonging to a single, presumably monophyletic, suborder (Notothenioidei) largely restricted to
Antarctica.

Because the Recent environment supports such a sparse fauna, we thought that a search for and
description of new fossil fishes from the area would ultimately lead to a better understanding of the
biogeography of Antarctica. Fossil fishes have been described from only a few areas of the Antarctic
region (text-fig. 1): 1, Cretaceous and Tertiary marine deposits of Seymour Island near the
north-eastern tip of the Antarctic Peninsula (Woodward 1908; Elliot et al. 1975; de Valle et al. 1976;
Cion eetal. 1977; Welton and Zinsmeister 1980; Chatterjee and Zinsmeister 1982); 2, Lower Jurassic
freshwater deposits of Southern Queen Alexandra Range of theTransantarctic Mountains in Victoria
Land (Schaeffer 1972); 3, Lower Devonian marine deposits of the Horlick Formation, Ohio Range
(Doumani et al. 1965); and 4, several small Devonian freshwater deposits between the Mulock and
Mawson Glaciers, Victoria Land (Woodward 1917, 1921; White 1968; Ritchie 1971; Gunn and
Warren 1962u; Young 1982; McKelvey et al. 1972). The two major Devonian freshwater fish-
producing units are the Lower or Middle Devonian Beacon Sandstone, and the Middle or Upper
Devonian (Givetian or Frasnian — Young 1982) Aztec Siltstone, both of which are in the Taylor
Group of the Beacon Supergroup (McKelvey et al. 1972). References to detailed locality information
are given in the text, and only general locality information will be given here.

In this paper we will systematically review the fossil fish fauna of the Antarctic region, including
some previously unreported Eocene taxa. For the sake of consistency, all names of implied ordinal
rank (including those of placoderms) end in ‘formes’, as suggested by Nelson (1984) and Berg ( 1940).
After Nelson’s ( 1 984) general classification, and Denison’s ( 1 978, 1 979) placoderm and acanthodian
classifications, the fossil fish taxa represented are:

class incertae sedis

Thelodontiformes

Turiniidae

Turinia sp. (Devonian]

AGNATHA

(Palaeontology, Vol. 29, Part 1, 1986, pp. 113-137. |

1 14

PALAEONTOLOGY, VOLUME 29

text-fig. 1 . Map of the Antarctic region showing localities of the fossils discussed in this paper. Major ice
shelves are represented by dense stipple. The narrowness of the continental shelf is indicated by the dashed
line of the 1000 m isobath. The heavy line is the Antarctic Convergence, a natural zoogeographic
boundary discussed in the paper. Redrawn from DeWitt (1971) with the location of the Antarctic

Convergence from Hedgpeth (1969)

GNATHOSTOMATA

CLASS PLACODERMI

Arthrodiriformes

Phlyctaeniidae

unnamed [Lower Devonian]

Holonematidae

Groenlandaspis antarcticus Ritchie 1975 [Middle or Upper Devonian]
Family incertae sedis

Antarctolepis gunni White 1968 [Middle or Upper Devonian]

GRANDE AND EASTMAN: ANTARCTIC FOSSIL FISH

115

Family indeterminate

Undetermined remains [Middle to Upper Devonian]

Phyllolepiformes

Antarctaspidae

Antarctaspis mcmurdoensis White 1968 [Middle or Upper Devonian]
Antiarchiformes
Bothriolepidae

Bothriolepis antarctica Woodward 1921 [Lower or Middle Devonian]
Bothriolepis sp. [Middle to Upper Devonian]

Bothriolepis sp. [Lower to Middle Devonian]

CLASS ACANTHODII

Acanthodiformes

Acanthodidae

ICheiracanthus sp. [Lower or Middle Devonian]

Climatiiformes

Gyracanthidae

Gyracanthides warreni White 1968 [Middle or Upper Devonian]

Order incertae sedis

Antarctonchus glacilis White 1968 [Middle or Upper Devonian]
Byssacanthoides debenhami Woodward 1921 [Lower or Middle Devonian]

CLASS CHONDRICHTHYES
Elasmobranchii

Xenacanthiformes

Xenacanthidae

Xenacanthus sp. [Middle or Upper Devonian]

Antarctilamna prisca Young 1982 [Middle or Upper Devonian]
Lamniformes
Odontaspididae

Eugomphodus macrota (Agassiz 1843) [Late Eocene or Early Oligocene]
Lamnidae

Carcharodon auriculatus (Blainville 1816) [Late Eocene or Early Oligocene]
Isurus sp. [Upper Cretaceous]

Squaliformes

Squalidae

indeterminate [Late Eocene or Early Oligocene]

Pristiophoridae

Pristiophorus sp. [Late Eocene or Early Oligocene]

Squatinidae

Squatina sp. [Late Eocene or Early Oligocene]

Rajiformes

Mylobatidae

unnamed [Late Eocene or Early Oligocene]

Order Undetermined
Mcmurdodontidae

Mcmurdodus featherensis White 1968 [Middle to Upper Devonian]
Undetermined Family

Undetermined selachian vertebral centra [Cretaceous]

Elolocephali

Chimaeriformes

Chimaeridae

llschyodus sp. [Late Eocene or Early Oligocene]

INDETERMINATE CHONDRICHTHYAN REMAINS

unnamed [Lower or Middle Devonian]

116

PALAEONTOLOGY, VOLUME 29

CLASS OSTEICHTHYHS
Crossopterygii

Osteolepiformes

Osteolepidae

Gyroptychius ? antarcticus (Woodward 1921) [Lower or Middle Devonian]

Gyroptychius sp. [Middle or Upper Devonian]

unnamed [Lower or Middle Devonian and Middle or Upper Devonian]

Actinopterygii

Chondrostei

Palaeonisciformes

Undetermined palaeonisciforms [Lower or Middle Devonian and Middle or Upper Devonian]
Neopterygii

Undefined Subdivision
Pholidophoriformes
Archaeomaenidae

Oreochima ellioti Schaeffer 1972 [Lower Jurassic]

Teleostei

Siluriformes

Family incertae sedis

unnamed [Late Eocene or Early Oligocene]

Superorder and order incertae sedis

unnamed [Late Eocene or Early Oligocene]

INSTITUTIONAL ABBREVIATIONS
AMF = The Australian Museum, Sydney.

AMNH = The American Museum of Natural History, New York, Department of Vertebrate Paleontology.
BMNH = The British Museum (Natural History), London, Department of Palaeontology.

CPC = The Commonwealth Palaeontological Collection, Bureau of Mineral Resources, Canberra, Australia.
FMNH = Field Museum of Natural History, Chicago, Vertebrate Paleontology Section, Department of
Geology.

NZGS = The New Zealand Geological Survey.

UCMP = Museum of Paleontology of the University of California, Berkeley.

UCR = University of California, Riverside, Department of Earth Sciences.

USNM = United States National Museum of Natural History, Washington.

SYSTEMATIC LIST OF FOSSIL ICHTHYOFAUNA

Superclass agnatha
Class incertae sedis
Order Thelodontiformes
Family turiniidae Obruchev 1964
Turinia sp. (description in preparation by Turner and Young)

Referred material. FMNH PF 9600 and 9602 (scales).

Geologic age. Devonian.

Locality. Mount Fleming, South Victoria land (near Mawson Glacier area), Antarctica. Detailed locality
information not available.

Comment. According to Turner (pers. comm.) this species appears to be closely related to some yet
undescribed species from China.

Superclass gnathostomata

Class PLACODERMI

Comment. All described placoderm material from the Antarctic Region consists of isolated dermal
elements, except for the holonematid Groenlandaspis antarcticus Ritchie 1975, which is known

GRANDE AND EASTMAN: ANTARCTIC FOSSIL FISH

117

ABC

text-fig. 2. Two Antarctic placoderm species known by articulated material, a, b, Groenlandaspis
antarcticus Ritchie, 1975, restoration of head shield and ventral trunk shield (alter Ritchie 1975);
C, Antarctaspis mcmurdoensis White, 1968 (head shield after White 1968). Abbreviations: amv = anterior
medio-ventral plate, avl = anterior ventrolateral plate, ce = central plate, il = interolateral plate,
ioc = infraorbital sensory canal, mg = marginal plate, nu = nuchal plate, pi = pineal plate,
pmv = posterior medianventral plate, pn = paranuchal plate, pro = preorbital plate, pto = postorbital
plate, pvl = posterior ventrolateral plate, ro + pi = rostro-pineal plate, ro + ptn = rostro-postnasal
plate, so c = supraorbital sensory line, sp = spinal plate.

by nearly complete head and trunk shields (text-fig. 2a-b), and the arctolepid Antarctaspis
mcmurdoensis , which is known by a partial skull roof (text-fig. 2c). Byssacanthoides debenhami
Woodward was originally described (1921) as a bothriolepid; but after further preparation. White
(1968, p. 12) found this species to be an acanthodian. Woodward (1921, p. 57) also mentions an
"Undetermined Coccostean’ based on some poorly preserved fragments (illustrated in Woodward
1921, figs. 23 and 24); White (1968, p. 22) examined this material and determined it was too poorly
preserved to be identified as ‘coccostean’. Ritchie (1971) mentions a large collection of largely
undescribed placoderm material at the Australian Museum in Sydney.

Order Arthrodiriformes
Family phlyctaeniidae Fowler 1947

Comment. The family Arctolepidae Heintz 1937 is considered (Denison 1978, p. 54) to be a junior
synonym of this family (Miles, 1965, originally referred to this specimen as an ‘arctolepidae plate’).
Phlyctaeniidae is also known from Devonian sediments of Europe, Spitsbergen, and North America
(Denison 1978). Species in the suborder Phlyctaenioidei have also been reported from South Africa
(Chaloner et al. 1980, p. 129).

unnamed (described in Miles 1965, p. 273)

Referred material. USNM 145422, a single left anterior lateral plate illustrated in Miles 1965, pi. 18, fig. 5.
Geologic age. Lower Devonian.

Locality. Horlick Formation of (he Ohio Range, Antarctica. Additional locality information in Miles 1965,
p. 273, and Doumani et al. 1965, pp. 243, 245.

Comment. Miles (1965, p. 274) stated, ‘The plate described above certainly belongs to a new species
of arctolepid [= phlyctaenid] and, in all probability, to a new genus’. But because of the lack of
additional material, he did not erect a new name for the taxon.

118

PALAEONTOLOGY, VOLUME 29

Family holonematidae Obruchev 1932
Groenlandaspis antarcticus Ritchie 1975, p. 571

Referred material. Holotype AMF 54334 (text-fig. 2a-b, a nearly complete head shield); several other head and
ventral shields deposited at AMF and listed in the type description.

Geologic age. Middle or Upper Devonian.

Locality. Aztec Siltstone at Mount Ritchie and elsewhere between Mulock and Mawson Glaciers, Antarctica
(more detailed locality information in type description).

Comment. This is the most complete described fish from the Devonian of Antarctica (text-fig. 2a-b).
The genus is also known from Greenland, Ireland, Turkey, England, and New South Wales,
Australia. The interrelationships of the Groenlandaspis species from these areas are unknown, so the
Antarctic species does not yet contribute information on the biogeographic affinity of Antarctica.

Family incertae sedis
Antarctolepis gunni White 1968, p. 21

Referred material. Flolotype BMNH P.49165 (dermal plate illustrated in White 1968, pi. 3, fig. I).

Geologic age. Middle or Upper Devonian.

Locality. Aztec Siltstone, Boomerang Range, between the Mulock and Mawson Glaciers, Antarctica. More
detailed locality information in White 1968, and McKelvey et al. 1972.

Comment. Only one specimen (P.49165) was definitely referred to this species, although BMNH
P.49165-49166 (White 1968, pi. 3, figs. 1 and 2) were tentatively referred to this species. White (1968,
p. 20) put this species questionably in Phlyctaenaspidae, but Denison (1978, p. 102) placed the genus
as Arthrodira incertae sedis.

Family indeterminate

Undetermined remains (described by White 1968, pp. 21-22)

Referred material. BMNH P.49167 (White 1968, pi. 3, fig. 3); NZGS 7395/17, 7396/4, 7396/5, 7399/12, 7399/14:
all fragments of isolated dermal elements.

Geologic age. Middle or Upper Devonian.

Locality. Various Aztec Siltstone localities between the Mulock and Mawson Glaciers, Antarctica (given in
White 1968).

Comment. Identified as ‘Undetermined Arthrodire Remains’ by White 1968, pp. 21-22.

Order Phyllolepiformes
Family antarctaspidae White 1968

Comment. This monotypic family is known only from Antarctica, and its relationships with other
placoderms are not well known. According to Young (1981, fig. 3 and text), Antarctaspis is most
closely related to Australian species of Phyllolepis.

Antarctaspis mcmurdoensis White 1968, p. 18

Type and referred material . Holotype BMNH P.49159 and P.49160 (partial skull-roof, illustrated in text-fig. 2c).
Two additional fragments (BNMH P.49161 and P.49162, illustrated in White 1968, figs. 11 and 12) were
tentatively referred to the species.

Geologic age. Middle or Upper Devonian.

Locality. In the Aztec Siltstone of the Lashly Mountains of Antarctica, between the Mulock and Mawson
Glaciers (see also White 1968).

GRANDE AND EASTMAN: ANTARCTIC FOSSIL FISH

1 19

Order Antiarchiformes
Family bothriolepidae Cope 1886

Comment. This family is also known from Devonian sediments in North America, Greenland,
Europe, USSR. China, and Australia.

Bothriolepis antarctica Woodward 1921, p. 52

Type and referred material. BMNH P. 1 2543-12552 (incomplete isolated plates from the head, trunk, and
appendages). Seven of the specimens are illustrated in Woodward 1921, figs. 3-9. BMNH P. 12535, 12540, 47824,
49170, 49154.

Geologic age. Lower or Middle Devonian (Beacon Sandstone) and possibly Middle to Upper Devonian (Aztec
Siltstone).

Locality. Beacon Sandstone of Granite Harbour, between the Mulock and Mawson Glaciers, Antarctica (see
Woodward 1921; McKelvey et id. 1972; Debenham 1921 ). Specimens from the Aztec Siltstone were also referred
to this species by White ( 1968).

Comment. Originally described as an ostracoderm because at the time of description antiarchs were
thought to be ostracoderms. Stensio (1948, p. 521), after reviewing Woodward’s material,
commented that fit is most likely . . . referable to Bothriolepis , but further material is needed for
a definite decision that this is actually true’. The relationships of this species to other bothriolepids are
unknown.

Bothriolepis sp. (mentioned in Ritchie 1971)

Referred material. Abundant material deposited in the Australian Museum, Sydney (reported in Ritchie
1971, 1975).

Geologic age. Middle or Upper Devonian.

Locality’. Aztec Siltstone, several localities between the Mawson and Mulock Glaciers, Antarctica, mentioned in
Ritchie (1971, 1975).

Comment. Ritchie (1971) reports that he collected much Bothriolepis material including complete
articulated head shields, and this material is being described by Young (in prep., citation in Young
1982, p. 820).

Bothriolepis sp. (described by White 1968, p. 15)

Referred material. BMNH P.12535-12542 (dermal plate fragments). Two specimens illustrated in Woodward
1921, figs. 1 and 2.

Geologic age. Lower or Middle Devonian.

Locality. Beacon Sandstone of Granite Harbour, between the Mulock and Mawson Glaciers, Antarctica (see
Woodward 1921; McKelvey et al. 1972; Debenham 1921).

Comment. Although Woodward (1921, p. 52) did not completely identify this material, he com-
mented that ‘several fragments . . . may certainly be referred to [Bothriolepis]' . White (1968, p. 15)
found, after further preparation of this material, that probably BMNH P.12535 and possibly the rest
of the material is referable to Bothriolepidae. White (pp. 16-17) also mentions some additional
bothriolepid fragments discovered later.

Class ACANTHODII

Comment. With the exception of ICheir acanthus sp. the only described acanthodian material from
Antarctica consists of partial fin spines. The 1C heir acanthus sp. material includes two scales.

White (1968) identified some Antarctic material as ICosmacanthus sp., which he included in

120

PALAEONTOLOGY, VOLUME 29

Acanthodii. Denison (1979, p. 56) determined that the type species for Cosmacanthus is an
indeterminate arthrodire, and that later species are presumably elasmobranchs. Therefore, the
Antarctic ‘ Cosmacanthus ’ material of White’s (BMNH P.49158) is not listed below; it should be
re-examined to determine whether it belongs in Cosmacanthus or should be placed in some
acanthodian taxon.

Order Acanthodiformes
Family acanthodidae Huxley 1861

Comment. This family is also known from Lower Devonian to Lower Permian sediments in North
America, Europe, Siberia, South Africa, and Australia (Denison, 1979).

1C he it acanthus sp. (described in White 1968, p. 25)

Referred material. BMNH P.12559 and 12576 (two scales). Illustrated in Woodward 1921, figs. 12 and 13.
Geologic age. Lower or Middle Devonian.

Locality. Beacon Sandstone of Granite Harbour, between the Mulock and Mawson Glaciers, Antarctica (see
Woodward 1921 and Debenham 1921).

Order Climatiiformes
Family gyracanthidae

Comment. The genus Gyracanthides has been recorded only from Victoria Land, Antarctica; from
near Mansfield in Victoria, Australia; and from South Africa (Chaloner et al. 1980). This
distribution reflects the geographic continuity of South Africa and Victoria with Antarctica during
Devonian times (text-fig. 6). Ritchie (1971, p. 70) mentions the occurrence of Gyracanthides also in
Devonian deposits of the Lashly Mountains, but Young (1982, p. 822) determined that material
belonged to the xenacanth Antarctilamna.

Gyracanthides warreni White 1968

Referred material. BMNH P.49156 and 49155 (both external impressions of partial pectoral spines) (illustrated
in White 1968, pi. 1, figs. 4 and 5).

Geologic age. Middle or Upper Devonian.

Locality. Aztec Siltstone deposits of the Boomerang Range, between the Mulock and Mawson Glaciers,
Antarctica (see White 1968).

Order incertae sedis
Antarctonchus g/acilis White 1968

Referred material. BMNH P.49164 (holotype) and NZGS 7395/7-7395/8, 7395/12-7395/16, 7395/19 (all fin-
spine fragments).

Geologic age. Middle or Upper Devonian.

Locality. Aztec Siltstone deposits of the Lashly Mountains and Boomerang Range, between the Mulock and
Mawson Glaciers, Antarctica (see White 1968 and Debenham 1921).

Comment. White (1968) did not give an opinion on specific relationships for this species and
monotypic genus; Denison (1979, p. 49) placed the genus as Acanthodii, incertae sedis.

Byssacanthoides debenham i Woodward 1921

Referred material. BMNH P.12553 (lectotype designated by White 1968, p. 12), P.12554 (illustrated in
Woodward 1921, pi. 1, figs. 10 and 1 1) (both fin-spine fragments).

GRANDE AND EASTMAN: ANTARCTIC FOSSIL FISH

121

Geologic age. Lower or Middle Devonian.

Locality. Beacon Sandstone of Granite Harbour, between Mulock and Mawson Glaciers, Antarctica (see
Woodward 1921 and McKelvey et al. 1972).

Comment. Monotypic genus, originally described as an antiarch placoderm but later placed as
Acanthodii incertae sedis by White (1968), Denison (1979), and others.

Class CHONDRICHTHYES

Comment. Below is the first report of any holocephalan or pristiophorid from the Antarctic region.
Although there is no known articulated fossil chondrichthyan material, some of the holocephalan
tooth plates appear to have come from a single individual. Previously, the total recognized
fossil chondrichthyan fauna of the region included only Eugomphodus macrota (Odontaspididae),
Carcharodon auriculatus (Lamnidae), and indeterminate species of Lamnidae, Squalidae,
Mylobatoidea, and Squatina. The only living chondrichthyans reported from the area are five
nominal species of skates (Andriashev 1965).

Other fossil chondrichthyans taxa have been erroneously reported from the Antarctic Region
( Ptychodus , Scapanorhynchus raphiodon , S. subulatus , hunts mantel li , hunts sp., and C archarias sp.
by de Valle et al. 1976 and I. novusl by Cione et at. 1977). These fossils were found by later workers
(Welton and Zinsmeister 1980) to have been misidentified (in the case of de Valle et al. 1976) or of
insufficient completeness to warrant such identification (in the case of Woodward 1908). Below, the
taxa recognized by Welton and Zinsmeister (1980) and the new taxa reported here will be listed
systematically.

Subclass ELASMOBRANCHII

Comment. It is difficult to derive any significant biogeographical information (other than range
extension) based on the Antarctic elasmobranchs because of inadequate preservation. Most of the
elasmobranch species are known only from isolated tooth fragments.

Order Xenacanthiformes
Family xenacanthidae Fritsch 1889

Xenacanthus sp. (described in Young 1982 and Ritchie in McKelvey et al. 1972, p. 351)

Referred material. CPC 21214 21217, 21228; AMF 54329-54331, 55573 (all isolated teeth, some of which are
illustrated in Young 1982, pi. 89, ligs. 1-4).

Geologic age. Middle or Upper Devonian.

Locality. Aztec Siltstone deposits of Portal Mountain and near Mount Ritchie, near Mawson Glacier (see
Young 1982), Antarctica.

Comment. This was the first xenacanthid material reported from Antarctica.

Antarctilamna prisca Young 1982

Referred material. CPC 21 187 (holotype), a partly articulated specimen illustrated in Young 1982, text-figs. 2
and 3a-d, and pi. 89, figs. 5-7; CPC 21 188-21 190, isolated scales; CPC 21 191, teeth; and AMF 55550, 55555,
55617; CPC 21 192, fin spines.

Geologic age. Middle or Upper Devonian.

Locality. Aztec Siltstone, near Mawson Glacier (see Young 1982), Antarctica.

Comment. Young (1982) specifies that this Antarctic material belongs to a species most closely related
to a Devonian Australian species (he, in fact, considers the Antarctic and Australian material to be
conspecific in this monotypic genus).

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PALAEONTOLOGY, VOLUME 29

Although Young (1982, pp. 822-823) does not formally include Antarctilamna in Xenacanthidae,
he places his monotypic genus as the sister-group of Xenacanthus (p. 838). It is therefore included
here in Xenacanthidae.

Order Lamniformes

Family odontaspididae Muller and Henle 1839
Eugomphodus macrota (Agassiz 1843)

Referred material. UCMP 1 16454-1 16460, incomplete teeth (some illustrated in Welton and Zinsmeister 1980,
fig. 4g-p), and 225 broken tooth crowns in the collection of the Ohio State University Institute of Polar Studies.
Description of material and locality in Cione et al. (1977), and Welton and Zinsmeister (1980, pp. 4-5), with
a detailed discussion of the stratigraphy in Woodburne and Zinsmeister (1984).

Geologic age. Late Eocene or Early Oligocene.

Locality. The La Meseta Formation, Seymour Island (64° 15' S., 56 45' W.), Antarctic Peninsula, in a coarse,
pebbly, fossiliferous shell bank.

Comment. Cione et al. 1977 also referred some material to Eugomphodus sp., which Welton and
Zinsmeister (1980, p. 7) stated ‘are probably Eugomphodus macrota \ Teeth reported as belonging to
this species are geographically widespread, known from Eocene sediments in North America, Chile,
Asia, USSR, and Africa (Welton and Zinsmeister 1980).

Family lamnidae Muller and Henle 1838

Carcharodon auriculatus (Blainville 1816) (= Procarcharodon auriculatus of Cione et al. 1977)

Referred material. UCMP 1 16453, a nearly complete anterior tooth lacking one cusplet (illustrated in Welton
and Zinsmeister 1980, figs. a-c).

Geologic age. Late Eocene or Early Oligocene.

Locality. The La Meseta Formation, Seymour Island, Antarctic Peninsula.

Comment. Some fragmentary material referred to Isurus by Cione et al. (1977) was placed in
Lamnidae as indeterminate by Welton and Zinsmeister ( 1 980, p. 7). Because this species is based only
on teeth, it is difficult to assess its geographic extent. It has been reported from Tertiary sediments of
North America, Europe, Africa, South America, Australia, New Zealand, and USSR.

Isurus sp., newly reported Antarctic specimen
Referred material. FMNH PF10294, a nearly complete tooth (text-fig. 3/;, i).

Geologic age. Upper Cretaceous.

Locality. Cretaceous-Tertiary boundary, Seymour Island, Antarctic Peninsula (Zinsmeister, pers. comm.).

Comment and description. A single, unicusped, anterior tooth with smooth cutting edges on the lateral
margins. The only specimens of Isurus sp. previously reported from the Antarctic region were from
Late Eocene or Early Oligocene sediments of the La Meseta Formation (Elliot et al. 1975; Cione et ah
1977). These previously reported specimens were found by Welton and Zinsmeister (1980) to be
unassignable to the genus, and are not included in the genus here.

Order Squaliformes
Family squalidae Leach 1818

indeterminate (described by Welton and Zinsmeister 1980, p. 3)

Comment. Recent squalids have a widespread distribution in marine waters of the Atlantic, Pacific,
and Indian Oceans, and fossils are also widespread in marine sediments.

text-fig. 3. a-g, Siluriformes, from early Tertiary deposits of Seymour Island, a-d, left pectoral fin spine
(FMNH PF10642, coated with ammonium chloride), x 2. a, anterior surface, b, posterior surface, c, dorsal
surface, d, ventral surface. e,f, anterior part of right dentary (FMNH PF10643), anterior pointing down, x 2-5.
e, view of toothed surface. /, medial view, g, a single isolated tooth, x2-5, from another dentigerous bone
(FMNH PF10644) associated with dentary in e and/. h and /', Isurus sp. (FMNH PF10294), x 1-6, from Upper
Cretaceous deposits of Seymour Island. Missing part of root. /;, anterior view, i, lateral view. Previously reported
specimens identified as hums sp. from Antarctica have been found to have been incorrectly identified (see text).
j-l, Pristiophorus sp. from early Tertiary deposits of Seymour Island, j, k , lateral (anterior facing left) and
anterior views of a single rostral tooth (FMNH PF10645c), x 2-9, dashed lines = restored outline. /, series of
isolated rostral teeth (FMNH PF 10645a 1), x 0-9; anterior facing down. This is the first report of a pristiophorid
from the Antarctic region, m-p, Chimaeridae (Vschyodus sp.) from early Tertiary deposits of Seymour Island.
m, «, dorsal fin spine, lateral (anterior facing left) and posterior view (FMNH PF 10646), x 1. o, p, palatine and
mandibular tooth (FMNH PF10647a-b), x IT; anterior facing left. This is the first report of a holocephalan

from the Antarctic region.

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PALAEONTOLOGY, VOLUME 29

Referred material. UCMP 121795, an incomplete tooth (illustrated in Welton and Zinsmeister 1980, fig. 2).
Geologic age. Late Eocene or Early Oligocene.

Locality. The La Meseta Formation, Seymour Island, Antarctic Peninsula (see Welton and Zinsmeister
1980). '

Family pristiophoridae Bleeker 1859
Pristiophorus sp., first report

Referred material. FMNE1 PF10645 (text-fig. 3/-/)— twelve rostral teeth including several nearly complete
specimens.

Geologic age. Late Eocene or Early Oligocene.

Locality. The La Meseta Formation, Seymour Island, Antarctic Peninsula.

Comment and description. This is the first report of a saw shark from Antarctica. The blade-like teeth
are of orthodentine, with smooth, unbarbed edges, and a root base that is claviform with a distinct
anteroposterior groove (for fitting against the lateral margin of rostrum). Because the teeth are
smooth (rather than barbed) they are thought to belong to Pristiophorus rather than Pliotrema or
Ikamauis (both of which have barbed rostral teeth). It is interesting to note that there are no known
fossil or Recent pristiophorids in South America south of northern Ecuador (Keyes 1982). The genus
Pristiophorus is fairly widespread, today living in Atlantic and Indo-west Pacific waters. Fossils are
also known from North America, Europe, South Africa, Asia, and Australia. The biogeography of
fossil and Recent pristiophorids was reviewed by Keyes (1982).

Family squatinidae Muller and Henle 1837
Squatina sp. (described in Welton and Zinsmeister 1980, p. 4)

Referred material. UCMP 121796-121797, two incomplete teeth (one illustrated in Welton and Zinsmeister
1980, fig. 3).

Geologic age. Late Eocene or Early Oligocene.

Locality. The La Meseta Formation, Seymour Island, Antarctic Peninsula (see Welton and Zinsmeister
1980). '

Comment. Squatinids are geographically widespread. Recent species (all belonging to a single
genus) occur in both Atlantic and Pacific waters, and fossils are ‘well represented in most Cenozoic
neoselachian assemblages’ (Welton and Zinsmeister 1980, p. 8).

Order Rajiformes

Family mylobatidae Muller and Henle 1837
incertae sedis (described in Welton and Zinsmeister 1980, p. 7)

Referred material. UCMP 1 16461, an incomplete medial tooth (lacking distal end of crown and one side of root).
Illustrated in Welton and Zinsmeister 1980, fig. 4d-f. Also, UCR 21089, 21169, 21170, 21230, and FMNH
PF 1 0678 1068 1 (partial teeth).

Geologic age. Late Eocene or Early Oligocene.

Locality. The La Meseta Formation, Seymour Island, Antarctic Peninsula (see Welton and Zinsmeister
1980).

Comment. Mylobatid rays are geographically widespread. Recent species occur in Atlantic, Pacific,
and Indian waters, and the fossils, like Squatina fossils, are ‘well represented in most Cenozoic
neoselachian assemblages’ (Welton and Zinsmeister 1980, p. 8). Although mylobatids are unknown
in the Recent Antarctic fauna, mylobatid teeth are common in the La Meseta Formation.

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Order Undetermined
Family mcmurdodontidae White 1968
Mcmurdodus featherensis White 1968, p. 9

Type specimen. BMNH P.49157, a nearly complete tooth (illustrated in White 1968, fig. 1).

Geologic age. Middle to Upper Devonian.

Locality. Aztec Siltstone deposits at Mount Feather, between the Mulock and Mawson Glaciers, Antarctica (see
White 1968).

Comment. Young (1982, p. 835) reported a second specimen of this species (CPC 21229, a tooth from
Mount Ritchie, between the Mulock and Mawson Glaciers, Antarctica).

Family indeterminate

Undetermined selachian vertebra! centra (described by Woodward 1908, pp. 1-2)

Referred material. Large centra (to 10 cm in diameter) illustrated in Woodward 1908, figs. 1-3.

Geologic age. Cretaceous.

Locality. Seymour Island.

Comment. These vertebrae were originally identified by Woodward (1908) as Ptychodus sp., but
Welton and Zinsmeister ( 1 980) showed placement in that genus to be tenuous, and they are probably
better placed as Elasmobranchii: indeterminate order.

Subclass HOLOCEPHALI
Order Chimaeriformes
Family chimaeridae Rafinesque 1815
llschyodus sp., first report

Referred material FMNH PF10647a b (palatine and mandibular tooth illustrated in text-fig. 3 o, /;); and UCR
21008 (dorsal spine illustrated in text-fig. 3 m, ri). Also FMNH PF10648-10653 (partial jaw elements).

Geologic age. Late Eocene or Early Oligocene.

Locality. The La Meseta Formation, Seymour Island, Antarctic Peninsula.

Comment. This is the first report of a holocephalan from Antarctica. A description of this new species
is currently in progress (Maisey and Grande). This material is extremely abundant in the La Meseta
Formation of Seymour Island.

INDETERMINATE CHONDRICHTHYAN REMAINS

unnamed (described in Woodward 1921, p. 56)

Referred material. BMNH P.12561 12563, 12589, 12590 (minute fragments of dermal armour and shagreen-
granules).

Geologic age. Lower to Middle Devonian.

Locality. Beacon Sandstone of Granite Harbour, between the Mulock and Mawson Glaciers, Antarctica (see
Woodward 1921 and Debenham 1921).

Comment. Woodward (1921) stated that the fragments were referable to a primitive ostracoderm or
elasmobranch group, possibly even to Cladoselachiformes. Gross (1950) and Tarlo (1966) suggested
that they might be referable to Psammosteidae (Heterostraci).

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PALAEONTOLOGY, VOLUME 29

Class OSTEICHTHYES
Subclass CROSSOPTERYGII
Order Osteolepiformes
Family osteolepidae Cope 1889
Gyroptychius! antarcticus (Woodward 1921, p. 58)

Holoptychius antarcticus Woodward 1921, pp. 58-59, pi. 1, figs. 25-29

Type and referred material. BMNH P.12573, lectotype designated by White (1968, p. 22), consisting of the
impression of a flank scale (illustrated in White 1968, fig. 14); and numerous other BMNH and NZGS
specimens, including a few teeth, part of a lower jaw, imperfect branchiostegal rays, a suboperculum, and a gular
plate (all disassociated).

Geologic age. Lower or Middle Devonian (Beacon Sandstone) and possibly also Middle or Upper Devonian
(Aztec Siltstone).

Locality. Originally described from the Beacon Sandstone of Granite Harbour, between the Mulockand Mawson
Glaciers, Antarctica. Specimens from the Aztec Siltstone were also referred to this species by White (1968).

Comment. Woodward described this species in the porolepiform genus Holoptychius based mainly on
a scale and a supposed clavicle fragment. White (1968, p. 22) further prepared and re-examined this
material and found the scales to be those of an osteolepid, and the ‘clavicle’ to be a small dorsal
central plate of an antiarch pectoral limb. White also added some osteolepid material from the Aztec
Siltstone (the teeth, suboperculum, gular plate, and branchiostegal rays) to Woodward’s original
material. White (1968, p. 25) admitted that his placement of this fragmentary material into the genus
Gyroptychius was tenuous. This material should, at best, probably be incertae sedis under
Osteolepiformes (a widespread order found also in Devonian sediments of North America, Europe,
Australia, and Asia).

Gyroptychius sp. (mentioned in Ritchie 1971, pp. 69-70)

Referred material. Some undescribed AMF material including a lower jaw (Ritchie 1971, fig. p. 70), and possibly
a nearly complete anterior half of a fish (mentioned in Ritchie 1971, p. 69).

Geologic age. Middle or Upper Devonian.

Locality. Aztec Siltstone deposits between the Mulock and Mawson Glaciers, Antarctica (see Ritchie 1971).

Comment. Gyroptychius is also reported from Australia (Young and Gorter 1981 ), and Europe and
Greenland (Thompson 1964), but the monophyly of the genus as currently defined is doubtful
(Young and Gorter 1981).

unnamed (described by Woodward 1921, p. 59)

Type and referred material BMNH P.12576, 12579, 12581, 12583, 12588 (scales and incomplete operculum,
illustrated in Woodward 1921, figs. 27-29).

Geologic age. Lower or Middle Devonian.

Locality. Beacon Sandstone of Granite Harbour, between the Mulock and Mawson Glaciers, Antarctica (see
Woodward 1921 and Debenham 1921).

unnamed (illustrated in McKelvey 1972, fig. 4)

Type and referred material. NZGS 234 (a disarticulated skull).

Geologic age. Middle or Upper Devonian.

Locality. Aztec Siltstone deposits between Mulock and Mawson Glaciers, Antarctica.

Comment. This specimen has not yet been described.

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127

Subclass ACTINOPTERYGII
Infraclass chondrostei
Order Palaeonisciformes

Undet. palaeonisciforms (described by Woodward 1921 and White 1968)

Referred material. Many BMNH and NZGS scales listed in Woodward 1921, p. 601 and White 1968, p. 24.
Woodward (1908, figs. 30-34) illustrates some of them.

Geologic age. Lower or Middle Devonian, and Middle or Upper Devonian.

Locality ■ Various Aztec Siltstone and Beacon Sandstone localities between the Mulock and Mawson Glaciers.

Comment. Woodward (1921, p. 601) tentatively suggested a resemblance of some of these to
Rhadinichthys, but White (1968, p. 24) pointed out that they also resembled several other genera.
White (1968, p. 24) determined that there were at least three palaeoniscoid taxa represented, but
found none of the material of sufficient preservation for more specific identification or description.

text-fig. 4. Oreochima ellioti Schaeffer. The only described fossil fish species from the Antarctic region
that is known by nearly complete articulated specimens. Restored line drawing taken from Schaeffer 1 972,

with permission of the author.

Infraclass neopterygii
Subdivision Undefined
Order ‘Pholidophoriformes’

Family archaeomaenidae Goodrich 1909
Oreochima ellioti Schaeffer 1972, p. 3

Type and referred material. AMNH 9910a-b (holotype — a complete fish, part and counterpart illustrated in
Schaeffer 1972, fig. 1 ) and AMNH 9922-9971 (partial to nearly complete fish, some illustrated in Schaeffer 1972,
figs. 4-8).

Geologic age. Lower Jurassic.

Locality. Sedimentary interbeds (freshwater deposits) of the Kirkpatrick Basalt, Ferrar Group, Queen
Alexandra Range, Antarctica (see Schaeffer 1972 and Grindley 1963).

Comment. Because the Tholidophoriformes’ is probably a non-monophyletic group (Patterson
1977) and the interrelationships of its members are poorly known, this species and family is placed in
an undefined subdivision of Neopterygii. This freshwater species is the only described fossil
vertebrate which is represented in Antarctica by nearly complete articulated skeletons (recon-
struction in text-fig. 4). It appears to be most clearly related to Australian species, because the family
Archaeomaenidae are restricted to Australia (Schaeffer 1972).

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PALAEONTOLOGY, VOLUME 29

Subdivision teleostei
Superorder ostariophysi
Order Siluriformes
Family incertae sedis
unnamed, first report

Referred material. A single pectoral spine (text-fig. 3 a-d), FMNH PF10642; and a partial dentary (text-fig.
3e-g), FMNH PF 10643.'"

Geologic age. Late Eocene or Early Oligocene.

Locality. The La Meseta Formation, Seymour Island, Antarctic Peninsula.

Description. Nearly complete left pectoral spine (33 mm in length) missing only distal tip and part of dorsal
surface of main shaft. Posterior dentitions (serrae) very strong, few in number (nine or ten), retrose, evenly
spaced, and single cusped. No well-developed anterior serrae. Main shaft with weakly developed subparallel
ridges, and at anterior-proximal end there are a few small tubercles.

A lower jaw (text-fig. 3e, /) and another toothed element associated with the jaw also appear to be
catfish bones. Specimen FMNH PF10643 is the anterior portion of a right dentary which is relatively massive
(text-fig. 3 f) for a catfish, and bears a broad band of closely and uniformly spaced teeth (text-fig. 3e). The teeth
are all hollow and broken off at the base, as is common in fossil catfish jaw elements (e.g. Lundberg 1975, figs. Id,
5d, f). One nearly complete villiform tooth (text-fig. 3g) is preserved on another toothed catfish element
(FMNH PF10644) associated with the dentary. The tooth is detached and lying on its side on the dentigerous
surface of the bone.

Comment. This is the first catfish reported from the Antarctic region. The lower jaw elements were not
associated closely enough with the pectoral spine to indicate with certainty that these bones belonged
to the same individual or even the same species, although they all belonged at least to individuals of
similar size. The spine (text-fig. 3 a-d) appears to have a fairly primitive morphology most similar to
ictalurids, bagrids, and diplomystids. It does not resemble any Recent marine catfishes (i.e. ariids,
plotosids). We therefore leave the spine and lower jaw as Siluriformes incertae sedis, and belonging to
one or possibly two different species.

Subdivision teleostei
Superorder incertae sedis
unnamed, newly reported Antarctic material

Referred material. Disarticulated and fragmented skeletal material including a variety of vertebral centra
of various sizes (specimens FMNH PF 10658- 10669 each with 1 to 5 centra for a total of twenty-one vertebrae);
basioccipital (FMNH PF10670); dentaries, some with conical teeth (FMNH PF10656-10657, 10671 10672);
premaxillae with conical teeth (FMNH PF10654-10655); maxillae (FMNH PF10674-10675); unidentified
jaw fragment with conical teeth (FMNH PF10676); pharyngeal tooth plate or part of fifth ceratobranchial
containing bases of small conical teeth (FMNH PF10677). Some of the jaw elements are illustrated in text-fig. 5.

Geologic age. Late Eocene or Early Oligocene.

Locality. The La Meseta Formation, Seymour Island, Antarctic Peninsula.

Comment. This material is a significant addition in quantity to the teleost fossils from Antarctica. It
contributes some insights into the biology of these fishes, but unfortunately offers no systematic
information. While it is reasonable to expect that ancestral notothenioids might be represented in this
material, there is nothing that allows a definitive diagnosis of this group. A morphological diagnosis
of the Notothenioidei includes (Eakin 1976) 33 flat, plate-like pectoral radials; pleural ribs poorly
developed and floating or absent; one nostril on each side of the head; non-pungent fin spines; usually
two or three lateral lines; no swim bladder; 10-19 principal caudal rays and 5-9 branchiostegals.
None of these features is evident in the fragmentary material from Seymour Island.

Although some of the fossilized vertebral centra are similar to those of some Recent notothenioids

GRANDE AND EASTMAN: ANTARCTIC FOSSIL FISH

129

text-fig. 5. a-c. Indeterminate teleost premaxilla from early Tertiary deposits of Seymour Island (resembling
a gadiform type, but specimens are too incomplete to make a positive assignment); in all three specimens,
anterior faces right. fl,ft(FMNH PF 10654). a shows tooth surface (tooth bases outlined with black lines) and b is
the medial surface (anterior processes restored with dashed lines, based on c), posterior end and teeth broken off,
x 1. c (FMNH PF 10655) anterior end of a premaxilla, probably belonging to the same species as the specimens
in a and b, x 2. d-i. Indeterminate teleost partial dentaries from early Tertiary deposits of Seymour Island. These
dentaries are peculiar in that they are extremely massive, and they have teeth that increase greatly in base width
posteriorly (most teeth were broken off near base so the tooth morphology is unknown). Tooth bases outlined
with black lines (d, g). d-f, FMNH PF10656, x 6. g-i, FMNH PF10657, x 1-3.

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PALAEONTOLOGY, VOLUME 29

the material is not distinctive enough for a positive identification. The vertebrae are, however, from at
least two different kinds of fishes and from fishes of greatly different sizes.

A large caudal vertebra (FMNH PF10667; maximum diameter of centrum = 4-7 cm) is generally
similar to those of the Recent nototheniid Dissostichus mawsoni. As in Dissostichus the centrum
contains deep fossae: two on each lateral aspect, one mid-dorsally and one mid-ventrally. This,
however, is not a characteristic unique to notothenioids. The fossil centrum is not as cancellous as
those of Dissostichus.

Casteel (1976) discusses a proportional method for estimating the size of a fish from the
dimensions of one of its bones by comparison with the bones of a type specimen of known size. We
applied this method to vertebra FMNFI PF10667. The centrum measures 3-27 cm anteroposteriorly.
The centrum of the first caudal vertebra of an 88 cm SL Dissostichus measures 1-43 cm. Solving for
the unknown the proportion yields 201 cm as the standard length of the specimen. D. mawsoni is both
the largest teleost and the largest Recent notothenioid in Antarctic waters. The largest specimen
captured by Eastman and DeVries (1981) measured 163 cm TL and weighed 60-3 kg. This is probably
close to maximum size for the species. The late Eocene fauna from Seymour Island thus contained
fishes considerably larger than those of the Recent fauna.

The centra of many of the smaller vertebrae in the sample resembled the large specimen
FMNH PF10667. For example, the arrangement and relative depth of the fossae was similar in most
centra that were not badly weathered. Of the twenty-one vertebrae in the sample, most were typically
amphicoelous with no evidence of a notochordal foramen (19%) or with a pin-hole sized foramen
(71%). Among Recent notothenioids, a pin-hole sized foramen is characteristic of D. mawsoni,
Notothenia angustata, and Bovichthys variegatus.

Buoyancy specializations among some Recent notothenioids include reduction in the extent of
skeletal ossification. Some species exhibit diminished vertebral amphiocoely with persistence of
a partial or complete notochord in a foramen traversing the middle of the centrum (Eastman and
DeVries 1982; DeVries and Eastman 1978, 1981 ). Thus the size of the notochordal foramen is related
to the degree of constriction of the notochord by the centra such that large foramina are present in
species with unconstricted ( Pleuragramma ) or slightly constricted (Act ho taxis) centra. Many Recent
notothenioids have moderately large notochordal foramina. When expressed as a relative
measurement the notochordal foramina are 20-38% of the diameter of the centra at the
intervertebral joint. Included in this group are species from the genera Trematomus, Notothenia,
Gymnodraco, Pagetopsis, Champsocephalus, and Chionodraco. Two (10%) of the teleost fossils from
Seymour Island have notochordal foramina similar in size to those of many Recent notothenioids.
However, this character is probably not unique to notothenioids.

Other teleost skeletal material from the La Meseta Formation comprises mainly jaw fragments.
The material is too incomplete to allow taxonomic identification, but it also indicates that some
specimens were larger than the Recent specimen of D. mawsoni mentioned above. The teeth of these
specimens are heavy and conical with both large and small series on a single jaw element. Teeth of
D. mawsoni are smaller, sharper, and curved posteriorly.

DISCUSSION

Although chondrichthyans are a minor component of the Recent Antarctic fauna, they are more
diverse in the fossil record of the continent. The three to five species of Recent rajids are most
numerous near the Antarctic Peninsula, South Georgia, and Kerguelen (Andriashev 1965; Bigelow
and Schroeder 1965; DeWitt 1971; Springer 1971).

There are several factors that may have contributed to the restriction of Recent chondrichthyans
from Antarctic waters. More than half of the living chondrichthyans are batoids (Compagno
1977), and they are generally most abundant in waters less than 1000 metres deep (Moyle and Cech
1982). Shallow benthic continental shelf habitat is limited in Antarctica (text-fig. 1 and see below).
Furthermore, the benthos consists largely of sessile filter-feeding invertebrates (Hedgpeth 1969) that
are mainly inedible (sponges, sea urchins, sea stars, sea spiders, and brittle stars). In addition,

GRANDE AND EASTMAN: ANTARCTIC FOSSIL FISH

131

molluscs, an important food group for many rajids, are poorly represented in the Antarctic fauna
(Dell 1969). It is possible that these circumstances, along with cold water temperatures, may have
served to eliminate many chondrichthyans from Antarctic waters during the late Tertiary.

This is the first report of Holocephali, Pristiophoridae, or Ostariophysi from the Antarctic region,
thus adding two more families to the chondrichthyan faunal list and a teleostean order (Siluriformes).
Previously, the only known chondrichthyan families represented were Odontaspididae, Lamnidae,
Squalidae, Squatinidae, and Myliobatidae (all represented by fossils only) and rajidae. Previously
known fossil teleosts were all Teleostei incertae sedis ; and known Recent teleosts are discussed below.

Although fossil fishes have been described from several localities in the Antarctic Region
(text-fig. 1), most of the material is very poorly preserved. Only one described species (text-fig. 4) is
represented by nearly complete articulated skeletons (the Jurassic Oreochima ellioti Schaeffer 1972).
The only other reasonably articulated specimen is a skull roof of Antarctaspis mcmurdoensis White
1968 (text-fig. 2). The rest of the known fossil fish material consists mostly of incomplete isolated
dermal head plates, scales, teeth, and other fragments, much of which cannot be accurately assigned
even to family.

Biogeographic Significance of the Fish Fauna. The evolution and biogeography of the Antarctic fish
fauna are associated with the break-up of Gondwana and subsequent development of the ocean
current pattern around Antarctica. These events may be briefly summarized as follows (Craddock
1982; Woodburne and Zinsmeister 1984). Gondwana was intact throughout the Palaeozoic (text-fig.
6e) and into the early Jurassic 195 ma (text-fig. 6d). Antarctica has been in a south polar position
throughout most of the Mesozoic (text-fig. 6c). During the Late Cretaceous (text-fig. 6c), South
America, Antarctica, and Australia were continuous, although there were prominent breaks between
all crustal blocks. Separation of Australia from East Antarctica may have begun in the Late Jurassic,
with the development of deep-sea conditions in this narrow trough about 80 ma. Final separation
took place between the Late Eocene and Early Oligocene (38 ma). Separation of West Antarctica
from South America was the last major event in the break-up of Gondwana and occurred between the
Early Cretaceous and the Late Eocene (text-fig. 6b). Deep-water conditions have prevailed in the
Drake Passage since at least 20 ma. Once Antarctica was isolated the unrestricted circum-Antarctic
current reached full development. By decoupling warm subtropical gyres from the continent the
circum-Antarctic current served as a barrier to heat flow and thermally isolated Antarctica.
Subsequently glaciers developed and the polar ice cap began to form (Kennett 1978, 1980).

The biogeographic significance of the Antarctic fauna is variable through geologic time, so it will
be discussed below by era.

Palaeozoic. All known Palaeozoic fishes from the Antarctic region are from Devonian rocks. The
Devonian is well before the break-up of Gondwanaland (text-fig. 6e), so the occurrence of the
widespread family Bothriolepidae is not too surprising. Few of the Devonian fish taxa are well
enough preserved to be included in phylogenetic studies of relationship and biogeography at the
species level (i.e. What other species of Bothriolepis is B. antarctica most closely related to, and where
did that sister species live?). In most cases preservation of the described Devonian fishes from
Antarctica is inadequate to enable positive assignment even to family, but there are exceptions. Of the
two described well-preserved Devonian species (both placoderms), one ( Groenlandaspis antarcticus)
is insufficiently known to yield any particular biogeographic affinity for Antarctica, and the other
(A. mcmurdoensis ) is thought by Young (1981, fig. 3c) to indicate a biogeographic relationship
between Antarctica and Australia. The presence of Antarctilamna (Xenacanthidae) also indicates an
Australian biogeographic affinity for Antarctica during Devonian time. The genera are both
represented only in Devonian deposits of Antarctica and Australia. The Antarctic-Australian
biogeographic relationship of the placoderms and xenacanths reflects the proximity of Australia to
Antarctica during Devonian time (text-fig. 6).

Mesozoic. Antarctic fossil fish material is described from two periods of the Mesozoic: the Cretaceous
(Woodward 1908, pp. 1-3) and the Lower Jurassic (Schaeffer 1972). Woodward’s (1908) Cretaceous

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PALAEONTOLOGY, VOLUME 29

text-fig. 6. South polar stereographic projection maps showing the position of Antarctica relative to other
continents during Recent (a). Late Eocene (b). Late Cretaceous (c), Early Jurassic (d), and Lower Devonian
(e) time, a d are after Smith and Briden ( 1977); e is after Smith et al. (1973). Fishes described in this paper lived

during these geologic times.

material consists only of a few isolated scales, and poorly preserved tooth and vertebral fragments,
which are indeterminate to order. Our Cretaceous material consists of only a single well-preserved
tooth (reported as hums sp.). Some additional unidentified Jurassic actinopterygian fragments are
illustrated in Tasch and Gafford ( 1984, figs. 2-6). Zinsmeister (1982) and Chatterjee and Zinsmeister
(1982) mention their discovery of some ‘Holosteans’ and other 'bony fishes’ from Cretaceous
deposits, but this material has yet to be described, and was unavailable for this study. These
Cretaceous bony fishes (probably belonging to only two identifiable teleost species) will be described
later by Grande and Chatterjee.

Of the described Mesozoic material the Jurassic species appears to be the most informative.
It is known by several nearly complete individuals and is reconstructed in text-fig. 4. This species
belongs to a freshwater family, Archaeomaenidae, which was previously confined to Australia
( Archaeomaena , Madariscus , and Wadeichthys). According to Schaeffer (pers. comm.) the Antarctic
species is most closely related to W. oxyops Waldman (1971) from the Lower Cretaceous of Victoria.
Thus, as during Devonian time, the Mesozoic material indicates an Australian biogeographic affinity
for Antarctica.

Cenozoic. All known Cenozoic fish fossils from Antarctica are from Seymour Island. The sediments
which contain these fossils are probably of Eocene age (Welton and Zinsmeister 1980, p. 2;
Woodburne and Zinsmeister 1984), although they were previously (Wilckens 1911) thought to be

GRANDE AND EASTMAN: ANTARCTIC FOSSIL FISH

133

Miocene. According to Welton and Zinsmeister (1980) and Woodburne and Zinsmeister (1984),
Tertiary rocks on the Island appear to range in age from Palaeocene (Cross Valley Formation) to
Late Eocene or Early Oligocene (La Meseta Formation). The fish fossils are from the La Meseta
Formation. Eocene fishes were first reported by Woodward (1908) and later by Elliot et al. (1977),
de Valle et al. (1976), Cione et al. (1977), and Welton and Zinsmeister (1980). Woodward (1908)
reported both teleost and shark material, and the rest of the papers cited above reported only shark
material.

The Eocene teleost material reported by Woodward (1908, pp. 3-4 and fig. 5) consisted only of
isolated partial centra, which he attributed to Nototheniidae because ‘they very closely resemble the
corresponding vertebrae of a large existing species of Notothenia' . It would not be surprising to find
notothenioid fossils in the area, because they dominate the Recent Antarctic fish fauna. However, as
mentioned previously, such an assignment based only on isolated centra seems somewhat tenuous.
The report of Notothenia from the middle-late Miocene of New Zealand (Stinton 1957) has since
been shown to be a misidentification (Fordyce 1982).

The fossil shark and catfish material reported contributes little biogeographic information other
than range extensions of already widespread taxa.

Recent. DeWitt (1971) summarized information concerning the distribution and endemism of the
Recent Antarctic fish fauna. The fauna comprises 120 species including one geotriid, one myxinid,
and four rajids. Among the teleosts, DeWitt notes that there are 4 families (with 10 species) of
deep sea fishes representing the orders Anguilliformes, Notacanthiformes, and Gadiformes. The
remaining 14 families of fishes are coastal. Within this group and excluding the notothenioids,
zoarcids and liparids are most numerous, with 1 1 and 5 species, respectively. However, these two
families as well as the four deep sea families provide no biogeographic information as they are found
in all deep, cold oceanic areas.

Among the remaining costal groups, there are 3 families of Gadiformes (6 species), one family of
Scorpaeniformes (one species), and one family of Pleuronectiformes (2 species). McGinnis (1982)
indicates that there are also 14 species of myctophids found south of the Antarctic Convergence and
that some of these species probably evolved in Antarctic waters in the Tertiary.

DeWitt’s (1971) compilation clearly indicates that 4 families of the suborder Notothenioidei
dominate the Recent fauna. With more than 80 species, this group includes at least 67% of the
species and 90% of the individuals in the Antarctic region. The incidence of endemism is 86% at the
species level. A few species from these families are found in New Zealand, southern South America,
and the Falkland Islands (Andriashev 1965). A fifth notothenioid family, the Bovichthyidae
(6 species), is distributed outside the Antarctic region in New Zealand, Australia, and southern South
America (Nelson 1984).

The Antarctic fish fauna is considerably less diverse than the Recent Arctic fauna. Although the
number of species in the two regions is not greatly disparate ( 1 20 for the Antarctic, 1 80 for the Arctic),
there are 32 families in the Arctic and only 18 in the Antarctic (Llano 1978). Furthermore, 21 of these
32 Arctic families are not present in the Antarctic. The Arctic fauna is dominated by cod, herring,
salmon, smelt, sculpin, and flatfish— groups that are either absent or poorly represented in the
Antarctic. The Arctic fauna does not contain a unique endemic group equivalent to the
notothenioids, and it consists, for the most part, of typical North Atlantic and North Pacific species.
The Arctic region is geologically younger and less isolated than the Antarctic, and these aspects of
biogeography are reflected in the composition of the Recent fauna.

While the Tertiary marine fauna of Australia is similar to the Recent fish fauna (Long 1982), this is
certainly not true of the Antarctic. As indicated previously, there have been marked reductions in
formerly diverse and abundant groups such as the Chondrichthyes. Moreover, the Recent fauna is
dominated by a single perciform suborder, the Notothenioidei. There are a number of factors
responsible for the unique and endemic Recent fauna:

1. Geographic isolation. The break-up of Gondwanaland and northward movement of other
southern continents left Antarctica isolated in a south polar position for most of the Tertiary. It is

134

PALAEONTOLOGY, VOLUME 29

separated from other southern continents by great distance, deep expanses of cold ocean, and
unfavourable surface currents. Colonization from the north is therefore difficult. The only shallow-
water migration route into Antarctic waters is through the islands of the Scotia Ridge that connect
southern South America with the Antarctic Peninsula.

2. Ocean current pattern. The circum-Antarctic current probably developed in the Late Oligocene
(22 ma), and it contributed to the thermal isolation of Antarctica with subsequent formation of
glaciers and ice sheets (Kennett 1978, 1980). Shortly thereafter the Antarctic Convergence (text-fig. 1)
began to develop and expand northward. The Convergence, located between 50 and 60° S., represents
the northern limit of the Antarctic Ocean and delimits a natural biogeographic province. The
Convergence is characterized by a sharp change in water temperature as well as in a number of other
oceanographic parameters. At the Convergence, northward moving Antarctic surface water
(temperature in winter less than 1 °C) sinks below the warmer less dense water to the north (Hedgpeth
1969). This region of abrupt thermal change has had a marked effect on the shallow-water fauna by
preventing southern migration and colonization of Antarctic waters by most pelagic fishes.

3. Age of the ecosystem as reflected in the extent and duration of glaciation. As indicated by the
palaeontological study of planktonic foraminiferal assemblages (Kennett 1978, 1980) the endemic
fish fauna has evolved under the influence of cold temperatures and sea ice since the Eocene-
Oligocene boundary 38 ma. Most of the non-notothenioid Cenozoic fauna probably died out as the
climate became colder. Glaciation was initiated about 25 ma in the Antarctic compared with 5 ma in
the Arctic (Johnson et al. 1982). The ecosystem and endemic fish fauna are thus specialized, having
evolved for a considerable period of time under cold conditions.

4. Depth and narrowness of the continental shelf. As a result of isostatic depression of the Antarctic
continent by the ice sheet, the depth of the continental shelf is four times greater than that of other
continents, and twice as great as that of the Arctic (Johnson et al. 1982). The shelf is also steep and
narrow, and Antarctica lacks the extensive archipelagos characteristic of the Arctic. Thus with deep
water close to the continental margin (text-fig. 1), the prime habitat, the continental shelf, for fish
diversity is very small in Antarctica.

It has been hypothesized that the ancestral notothenioid stock has been associated with Antarctica
at least since the waters began to cool down 38 ma (Regan 1914; Norman 1938; DeWitt 1971 ). Low
water temperatures, limited and deep continental shelf habitat, extreme geographic isolation, and
the absence of south-flowing surface currents have all probably contributed to the paucity of non-
notothenioid fish groups in Antarctic waters. Recent notothenioids are a diverse group of fishes that
have filled ecological roles normally occupied by other fishes in temperate oceans (Eastman and
DeVries 1981, 1982).

Summary of Biogeographic Significance. The Antarctic ichthyofauna shows an Australian affinity
during the Palaeocene and early Mesozoic that is not so visible in the Recent Antarctic ichthyofauna.
The apparent disappearance of this Antarctic-Australia pattern through time is probably due to
extinction (i.e. of Archaeomaenidae, Xenacanthidae, and Placodermi). The phylogenetically
younger groups (e.g. Teleostei) in the Recent fauna may reflect younger geographic patterns
(text-fig. 6) than were evident by the phylogenetically older group (e.g. Acanthodii). Changing
patterns of biogeographic affinity through time are probably not unusual, and have been documented
elsewhere (Grande 1985).

Acknowledgements. We would like to thank Drs Michael O. Woodburne and William J. Zinsmeister for making
the Seymour Island material available to us for study and for depositing it at the Field Museum.

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LANCE grande

Department of Geology
Field Museum of Natural History
Roosevelt Road at Lake Shore Drive
Chicago, Illinois, 60605

JOSEPH T. EASTMAN
Department of Zoology
Ohio University
Athens, Ohio, 45701

Typescript received 12 February 1985
Revised typescript received 24 April 1985

SHELL STRUCTURE, GROWTH, AND
FUNCTIONAL MORPHOLOGY OF AN
ELONGATE CRETACEOUS OYSTER

by KIYOTAKA CHINZEI

Abstract. Konbostrea (gen. nov.) is an aberrant oyster of the Crassostrea group, characterized by its
dorsoventrally elongated stick-like shell. It is found in life position, perpendicular to the bedding in brackish-
water muddy deposits of the Upper Turonian to Upper Coniacian, in Sakhalin and north Japan. A narrow body
space is restricted to the ventral end of the shell. The ligamental area is very small, separated from the body space,
and the ligament is considered to have been active only during the younger stages of growth. The adult animal
most probably took advantage of the elasticity of the thin, flat, right valve to open its shell. Having reached its
adult width the shell grew only in a ventral direction, at an apparently constant rate, without notable increase in
the size of the body cavity. The shell is composed of an outer foliated layer which defines the structural
framework of the shell, and inner chalky deposits which fill in most of the inner space. All these characteristics
are thought to result from adaptation to keep up with rapid sedimentation on a soft muddy bottom. Konbostrea
constantly grew upward, accumulating chalky deposits to maintain the body above the rising sediment surface.

Konbostrea konbo (Hayasaka and Hayasaka, 1956), here recognized as the type species of a new
genus, is an aberrant oyster characterized by an extremely elongated, stick-like left valve with a very
thin right valve of the same height. The oyster typically attains a height of 1 m. The main part of its left
valve is composed of massive shell, leaving no space for the soft body, which is restricted to the ventral
end of the valve. The oyster is closely related to the Crassostrea group of the Ostreidae. When
first described as Ostrea konbo (Hayasaka and Hayasaka 1956), its massive shell was thought to
be a part of the hinge area of a huge oyster. K. konbo is known from Turonian and Coniacian
intertidal or brackish-water deposits in southern Sakhalin (USSR), Hokkaido, and northern
Honshu (Japan).

The purpose of this paper is to describe the morphology, shell structure, and growth pattern of
K. konbo. The palaeoecology and adaptive significance of this peculiar shell will also be discussed.

Oysters of the Crassostrea group are suspension feeding, sessile animals which usually live on soft
muddy bottoms. Suspension feeding and the sessile habit are seemingly incompatible with life on a
soft muddy bottom with rapid sedimentation. The elongated shell form and gregariousness that are
characteristic of the Crassostrea group ( Crassostrea , Striostrea , and other oysters living on mud) are
best understood as adaptive characters employed by these oysters to avoid burial in rapidly
accumulating mud.

The stick-like shell of K. konbo is considered to represent an extreme example of the elongation
strategy employed by these oysters (Chinzei 1982«; Seilacher 1984). Other examples of such
elongation are seen in deeply conical forms of Saccostrea and Striostrea , in which the free valves act
as lids. The development of elongated, conical shells occurs not only in bivalves, but also in other
groups such as brachiopods, corals, and barnacles. However, the elongation of both valves, such as
that found in Konbostrea , is not common. Lithiotis and Cochlearites , bivalves of isognomonid or
bakevelliid affinity found in the Lower Jurassic of the Tethyan region, are analogous to Konbostrea in
overall shell form and in shell structure (Chinzei 1 982 a). Comparison of these forms clarifies the basic
adaptive and structural constraints that determined their morphologies.

The specimens used for this study are deposited in the Department of Historical Geology and Palaeontology,
University Museum, University of Tokyo: Reg. nos. MM 17080 to MM 17139.

| Palaeontology, Vol. 29, Part 1, 1986, pp. 139-154, pi. 18.|

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PALAEONTOLOGY, VOLUME 29

SYSTEMATIC PALAEONTOLOGY

Although the oyster described here has many features in common with species of Crassostrea and
other ostreid genera, it is unique in its extremely elongated shell form and other morphologic
characters related to the elongation. As the characters described below are stable among the
populations observed and are quite distinct from those of other genera, 1 propose to establish a
monospecific new genus belonging to the Subfamily Ostreinae. The word ‘konbo’ means club or stick
in Japanese.

Genus Konbostrea gen. nov.

Type species. Ostrea konbo Hayasaka and Hayasaka, 1956, pp. 163, 164, pi. 12, figs. 1 and 2.

Diagnosis. Extremely elongated oyster; left valve very long, dorsally very thick, with anterior and
posterior margins subparallel to each other; space for the soft parts with a deep umbonal cavity,
located at the ventral end of the left valve; right valve of same height as left valve, flat and extremely
thin except in the umbonal region; ligamental area of the adult shell separated from the dorsal margin
of the body space by long cardinal area; ligament active only during the young stage.

Comparisons. Konbostrea has many features in common with Crassostrea Sacco. 1897 ( sensu Stenzel
1971 ). In particular the morphology of the ligamental area is essentially the same, although it is very
small relative to shell height in Konbostrea. The juvenile shells of the two genera are similar in outline
and hinge structure, suggesting an evolutionary origin of Konbostrea from Crassostrea. The adult

text-fig. 1. Localities where Konbostrea konbo (Hayasaka and
Hayasaka) has been recorded.

CHINZEI: ELONGATE CRETACEOUS OYSTER

141

shell of Konbostrea differs from that of Crassostrea in its separation of the ligamental area from the
dorsal margin of the body space. It is readily distinguishable from elongated rudistiform ecomorphs
(Stenzel 1971) of Saccostrea Dollfus and Dautzenberg, 1920, and Striostrea Vyalov, 1936, by the
same character.

Localities and geologic age. The type locality of K. konbo is upstream on the Sentarozawa River, Kiyozumi,
Mikasa-shi, Hokkaido (LIpper Turonian, the uppermost part of the Mikasa Formation of the Middle Yezo
Group). The oyster is also known from: the upstream area of the West Sakutan River, on the west coast of
Sakhalin (Upper Cretaceous, Hayasakaand Hayasaka 1956); the southern limb of the Hatonosu Dome, Yubari-
shi, Hokkaido (Turonian Mikasa Formation, oral communication from S. Kanno): south tributary of the
Edanarisawa River, Kuji-shi, Iwate Prefecture (Upper Coniacian Tamagawa Formation of the Kuji Group);
Irumasawa, Ohisa, Iwaki-shi, Fukushima Prefecture (Upper Coniacian Tamayama Formation of the Futaba
Group, oral communication from I. Obata, geologic age based on Obata and Suzuki 1969). All these localities
except Sakhalin are in north-east Japan (text-fig. 1). The geologic ages of the oyster-bearing beds are based on
the work of Matsumoto et at. (1982).

MODE OF OCCURRENCE, INFERRED MODE OF LIFE
AND POPULATION DENSITY

At the type locality, individuals of K. konbo are found densely crowded together, forming an oyster
bed about 2 m thick. The sediment surrounding the oysters is a poorly sorted, dark grey sandy
mudstone. The oysters are standing perpendicular to the bedding with their umbones pointing
downward in the middle part of the bed, while they he parallel to the bedding at the bottom and top of
the bed. The upright orientation is apparently the living position of this oyster. The horizontal shells
are considered to have been displaced by wave or current scouring, because most of these shells are
broken, and do not show any preferred orientation, some lying with the thin valve facing down and
others with it up. Several of the individuals found in life position occur as bouquet-like clusters, in
which the juvenile shells radiate away from one another and then turn upward to grow parallel as
adults. The oyster bed occurs as a lens within the sandy mudstone. The mudstone is overlain by fine-
grained sandstone about 30 m thick, succeeded upward by ammonite-bearing mudstones. It is
underlain by medium-grained to coarse-grained sandstone, 1 0 to 15m thick, beneath which are thick
mudstones with frequently intercalated thin coal seams. Thus the oyster bed occurs in sediments that
are transitional between non-marine and marine facies.

Similar circumstances were observed at the Kuji locality. Flere the oysters are crowded in dark
grey, sandy mudstone T5 m thick, about the same height as the individual oysters. Oysters are found
standing perpendicular to the bedding, their umbones pointing down in part of the exposure, and
lying obliquely in the other part (text-fig. 2). Where they are oblique the shells have been broken at the
same level just above the umbones, indicating that the oblique position is due to later deformation of
the bed. The oyster bed is intercalated in coarse-grained, cross-laminated sandstone of the basal
member of the Kuji Group. The sandstone contains coaly matter and conglomerate lenses. These
have been considered to be non-marine or brackish-water deposits (e.g. Tanai 1979). In the Kuji area,
Konbostrea is limited in its distribution to the innermost part of a triangular Cretaceous basin, 10 km
wide and 15 km long, which opens toward the Pacific. Ordinary Crassostrea banks are found at the
same stratigraphic level along the middle and outer margins of the basin. The areas of distribution of
the two oysters can be sharply demarkated, for no intermediate forms between the two are found.

Upright orientation of this extremely long, narrow shell and preservation of the thin outer
prismatic layer of the shells suggest that they lived with most of the shell buried in the sediment. The
sediment supported the shell to keep the orientation and protected the fragile prismatic layer from
erosion. The shells show no preferred orientation in the plane of the bedding. No other fossils have
been found within the oyster beds or in the stratigraphically adjacent sediments except for traces of
boring sponges on the surface of the oyster shells. These traces are seen on many of the well-preserved
individuals.

Based on these observations the oysters are thought to have been living in intertidal or brackish

142

PALAEONTOLOGY, VOLUME 29

text-fig. 2. Sketch of part of a Konbostrea bed on the south tributary of the Edanarisawa River, Kuji-shi, north
Japan (Kuji locality), showing an excavated section oblique to the bedding. Most of the Konbostrea shells have
been broken near the umbo, and lie at about 60° to the bedding plane, sdy-md: sandy mudstone; c-sd: coarse-
grained sandstone.

waters, on a muddy bottom, maintaining an upright position with most of the shell sticking into the
mud. The absence of other marine fossils suggests very restricted marginal marine conditions for the
habitat of Konbostrea.

The population density of the oysters can be measured directly where the original relative positions
of the individuals are preserved. Measurements were made using the stretched line method (e.g. Ager
1963, p. 228). Along the vertical section of the bed the number of individuals falling within a one
metre horizontal line was counted, and then squared to obtain the density per square metre of the
horizontal surface. The density is about 350/m2 (three counts: 289, 361, 400) at the type locality, and
218/m2 in average (thirteen counts: observed range 144-324) at the Kuji locality where the
individuals are larger than those at the type locality.

MORPHOLOGY OF KONBOSTREA KONBO

Outlines

K. konbo is characterized by a dorsoventrally elongated shell which reaches a maximum of more
than 1 m in height (text-fig. 3). While the right valve is extremely thin and flat, most of the left valve
is thick, with a squarish or sometimes semicircular outline in transverse cross-section. The space
occupied by the soft tissues (hereafter denoted as the body space) is located at the ventral end of
the left valve.

CHINZEI: ELONGATE CRETACEOUS OYSTER

143

The length (distance between subparallel anterior and posterior margins, the ‘width' of the gutter-
shaped shell) of the left valve is 4 to 8 cm and its inflation is 3 to 4 cm in typical adult shells. One
individual having a flat shape, 10 cm long and 1-5 to 2 0 cm thick, was obtained. Shell length and
inflation change little or not at all towards the ventral margin. The height, on the other hand, varies
considerably. It is usually 80 to 100 cm in fully grown adults. The largest individual observed at the
outcrop reaches 120 cm. As the shell surrounding the body space is very fragile, because of its
thinness, most adult specimens to hand are incomplete. The overall form is variable among
individuals; it is generally straight, but broadly curved or sinuous shells are found quite often. Some
individuals exhibit zigzag changes in growth direction. The majority of the specimens from the type
locality are smaller than those from other localities. They are 50 to 70 cm high, 4 to 5 cm long, and 2 to
3 cm thick on average.

As the left valve is squarish in transverse section, the anterior and posterior walls are set off from
the main surface of the valve. The main surface is flat or very gently inflated, and constitutes the
‘bottom’ of the gutter-shaped left valve. As both walls are usually turned inward along the
commissural margin the greatest dimension measured parallel to the length axis of the left valve tends
to pass through the middle part of the walls (text-fig. 3).

The right valve has nearly the same height and length as the left valve. As the length of the right
valve must correspond to the maximum length of the left, the anterior and posterior margins of the
former usually extend out beyond the margins of the latter. The right valve is flat, about 2 mm thick in
the main part. Around the body space it is extremely thin, less than 1 mm, and flat without any cavity
or depression for the soft body. It is thick in the umbonal region. Just behind the ligamental area of
the right valve the outer layer is padded by a substantial inner layer about 1 cm thick in most
specimens (see text-fig. 6).

The surfaces of both valves are undulating but smooth, ornamented with closely spaced growth
lines. Their surfaces are covered by a thin prismatic layer. The margins of the growth lamellae are not
imbricated. The anterior and posterior walls of the left valve are rough, with closely spaced growth
squamae running slightly oblique to the commissural plane. Throughout the long cardinal area the
commissural plane is flat, forming a cardinal platform, on which no apparent structure is visible. In
all specimens the right valve is found attached tightly to the cardinal platform of the left valve. The
two valves are so tightly attached, they are usually difficult to separate along the commissural plane.
The commissural plane is hardly distinguishable, even on transverse cross-sections of the shell.
Around the body space, in contrast the two valves are not in contact, leaving the ventral margin
gaping. No chomata are present along the entire commissural margin.

K. konbo was initially attached to a hard substrate such as other oyster shells or stones, cemented
by the umbonal region of the left valve. Accordingly the umbo is irregular in shape, although the
attachment area is usually very small, 1 to 2 cm in diameter, and has little influence on the overall shell
outline. Juvenile shells are sometimes found attached to the outer shell surface around the body space
of the adult.

Body Space

The body space is usually about 25 to 35 cm high and 4 to 6 cm in length. It is box-shaped with
anterior and posterior walls. The walls become lower, thus the space becomes shallower, toward the
ventral margin, which is broadly rounded. The shell of the central part of the body space is very thin,
usually 1 to 2 mm. There is a deep cavity extending below the cardinal area back towards the umbo.
This cavity forms a compressed cone, usually about 2 to 3 cm deep, 5 cm at the maximum. In some
individuals the end of the cavity is subdivided into two or three narrow conical cavities. As the shell
above the umbonal cavity becomes extremely thin towards the margin of the body space, and is
hardly separable from the right valve, the configuration of the cardinal margin of the space is
uncertain.

The adductor muscle scar is large, 1 -5 to 2 0 cm in diameter, semicircular or lunate, dorsoventrally
elongated. In the left valve it is located near the centre of the body space, where the shell becomes

144

PALAEONTOLOGY, VOLUME 29

text-fig. 3. Overall shape and cross-sections of Konbostrea konbo. The sketch is based on specimen UT
MM 17080 (refer to PI. 18, figs. 1 and 2), partly reconstructed, a, left valve, b, posterior view, c, right valve, d,
transverse cross-sections. LV, RV: left and right valves; aa: attachment area; bdy: soft body space; i.tb: internal

tube; juv: juvenile shells attached to the left valve.

CHINZEI: ELONGATE CRETACEOUS OYSTER

145

abruptly thin. In some young individuals the scar is shallowly depressed, and the surface is tilted more
or less dorsally. In the right valve, however, the scar is not observable even on well-preserved
specimens, probably because of the thinness of the shell.

Ligament al Area

The shell has a small ligamental area adjacent to the umbo (PI. 18, figs 3 and 4). In the adult shell the
ligamental area is about 1 to 2 cm high, separated from the body space by a long cardinal area. The
structure of the ligamental area is similar to that of young stages of Crassostrea. The area consists on
the right valve of a central resilifer, with narrow, indistinct bourrelets along both sides. The resilifer

text-fig. 4. Internal tube of the left valve, a, optical photograph of a cross-section around the tube, x 25.
B, optical photograph of the chalky deposits near the internal tube showing regular growth lines, x 25. c,
SEM showing the foliated layer around the wall of the tube and surrounding chalky deposits, x 270. The

section polished and etched by weak acid.

146

PALAEONTOLOGY, VOLUME 29

RIGHT V.

Prm ANT.—

— POST.
LEFT V.

prm

add. my

text-fig. 5. Transverse cross-section of the
left valve of Konbostrea konbo (specimen UT
MM 17082 from the Kuji locality). ANT.,
POST.: anterior and posterior sides; add. my:
sparry calcite layer probably replacing the
adductor myostracum; chk: chalky deposits;
com: commissure plane; fol: foliated layer;
i.tb: internal tube; prm: prismatic layer.

pit of the left valve is deeply excavated. The resilifer is well inflated, and its supporting buttress is very
high relative to the size of the resilifer. Thus the growth trend of the ligamental areas of the two valves
is highly oblique to the general direction of the shell elongation (see text-fig. 6).

Internal Tube

A striking structural feature seen on cross-sections of the left valve is a narrow internal tube (text-fig.
4). The tube is continuous from the conical end of the body space to just behind the ligamental area.
Viewed in longitudinal sections, it passes through the chevron-shaped turning point of the growth
lines. The tube is 0-5 to 1 0 mm in diameter, and its inner surface is coated by a foliated layer, 0T to
0-15 mm thick (text-fig. 4). In specimens where the umbonal cavity is subdivided, there are tubes
corresponding to the number of conical spaces. As the tube is now void or filled with transparent
sparry calcite, it appears to have been hollow or filled with soft tissue during the life of the animal.

SHELL MICROSTRUCTURE

General Features

When the thick left valve is observed in cross-section, two distinctly different parts are visible, a
lamellar outer layer and porcellaneous inner material (text-fig. 5). The outer layer constitutes the
bottom of the box-shaped left valve and its anterior and posterior walls. The walls are composed of
foliated material, with intervening porcellaneous lenses. Growth lines are observable in the lenses.
The inner part of the left valve consists mainly of massive porcellaneous material with sparsely spaced
growth lines. The porcellaneous part is considered originally to have been very porous chalky
material. No aragonitic layer is seen on the surface of the ligamental area. The surface of the ligament

EXPLANATION OF PLATE 18

Eigs. 1-4. Konbostrea konbo (Hayasaka and Hayasaka, 1956), Kuji, north-west Japan, Upper Coniacian. la, b.
University Museum, Tokyo, UT MM 17080. Right valve a, umbonal part; b, ventral part). Surface is
unwhitened to show areas of dark colour where it is covered by the prismatic layer, x 0-42. 2a, b , left valve of
same specimen as fig. 1, x 0-42. 3, UT MM 17081. Ligamental area of adult right valve. In this specimen the
area below the resilifer is covered by part of the inner layer of the left valve, x 0-82. 4, Ligamental area of left
valve of same specimen as fig. 3. The inner layer below the ligament pit is peeled off and attached to the right
valve shown in fig. 3 x 0-82.

PLATE 18

CHINZEI, Konbostrea konbo (Hayasarka and Hayasarka, 1956)

148 PALAEONTOLOGY, VOLUME 29

pit is composed of foliated material. Here, the foliation stands at a high angle to the surface of the pit
and is gently arcuate.

The right valve is composed simply of a thin foliated layer, except in the umbonal region. Sheets of
foliated material are arranged nearly parallel or slightly oblique to the outer surface of the valve. The
umbonal region of the right valve is composed of an outer foliated layer 1 -0 to 1 -5 mm thick, and inner
chalky deposits. The surface of the ligamental area is also made up of foliated material which rapidly
wedges out into the chalky deposits below the umbo. The inner chalky layer is thickest just behind the
resilifer. It thins ventrally and toward the shell margins, thus filling the inner space formed by the
inflation of the resilifer (text-fig. 6).

Prismatic Layer

The outer surfaces of both valves, except the walls of the left valve, are covered by a thin prismatic
layer which is visible as a dark grey or brown coating on the shell surface (PI. 18, figs. 1 and 2). The
thickness of the prismatic layer is 0T5 to 0-3 mm over most of the right and left valves. Prismatic
crystals are arranged nearly perpendicular to the surface, each straight or slightly curved. The prisms
are irregularly polygonal in section, often twisted, and sharp or blunt at the end. Growth lines
subparallel to the shell surface are visible, cutting across the prisms.

Foliated Layer

Foliated material constitutes the outer part of the shell. It also forms a thin coating of the internal
tube. Seen with the SEM on a fractured surface parallel to the shell surface, the outer foliated layer
appears to be built up of very long, lath-like, narrow, and thin crystals of calcite, arranged in parallel
to form compound sheets. The orientation of the crystals changes abruptly, and sheets of different
orientation either overlap or abut one another at the same level. In cross-section the lath-like crystals
appear as tabular blocks or layers. Differences in orientation of the crystals are seen on SEMs of the
section, etched by weak acid.

Chalky Deposits

The inner porcellaneous part of the left valve is composed of irregular prismatic or granular calcite.
Prismatic calcite crystals intersect at acute angles and are usually arranged nearly perpendicular to
the growth lines. The porcellaneous part of the K. konbo shell is inferred to represent altered chalky
deposits, comparable with those of fossil and living Crassostrea.

The white, soft chalky deposits in the shell of Crassostrea and other ostreid species (e.g. Taylor et
al. 1969; Stenzel 1971) are very porous, composed of thin plates of calcite with much void space. The
calcite plates interlock with each other in an irregular manner, or are disposed subparallel to one
another, connected by smaller calcite flakes. In fossil Crassostrea shells a series of different alteration
states can be observed, from porous chalky deposits to aggregates of parallel or sometimes radial
calcite prisms and grains. The alteration apparently proceeded by overgrowth of calcite on the plates
and flakes, until all the void spaces were filled. The porcellaneous part of the Konbostrea shell is
similar to such heavily altered chalky deposits, in both crystal size and structure.

Growth lines appear as thin, dense aggregates of smaller crystals in the altered chalky deposits.
They are generally sparse, but they become more numerous and clearly distinguished around the
internal tube, where these deposits last formed. Growth lines are visible also in the lenticular chalky
deposits of the walls of the left valve.

Adductor Myostracum

No aragonitic myostracum has been observed directly in Konbostrea. The position of the adductor
myostracum in the left valve is suggested in many individuals by a narrow vein filled with transparent
sparry calcite, within the foliated layer (text-fig. 5). The posterocentral position of this vein and its
length are comparable with the position and diameter of the adductor muscle impression observed in
the well-preserved specimens. The aragonitic myostracum of oysters is easily leached in general.

CHINZEI: ELONGATE CRETACEOUS OYSTER

149

text-fig. 6. Ontogenetic change in the shell
form of Konbostrea konho, restored by trac-
ing successive growth lines of specimen UT
MM 1 7083 from the Kuji locality, a, juvenile
stage before accumulation of the chalky
deposits. b, start of accumulation of chalky
deposits in the left valve, c, later stage of the
active ligament, d, final stage of the active
ligament; the ligament is barely connected
with the soft body space, but the ventral end
cannot now be closed without bending be-
cause of obstruction by the mound of the
chalky deposits behind the ligamental area.
e, longitudinal cross-section of the liga-
mental region of the specimen from which
restorations a to d were made. LV, RV:
left and right valves; aa: attachment area;
bdy: soft body space; chk: chalky deposits;
com: commissural plane; fol: foliated layer;
i.tb: internal tube; lig: ligamental area; vg:
ventral gape.

leaving a cavity (e.g. Stenzel 1971, p. N981). The space filled with sparry calcite is seen in many
specimens of Konbostrea at the same position, so it may be confidently interpreted as the trace of the
formerly aragonitic myostracum. No such trace is seen in the right valve, probably due to the extreme
thinness of its myostracum. The inferred myostracum of the left valve is located very close to the shell
surface, the shell thickness outside it being usually less than 1 mm. The foliated layer outside the
myostracum is weakly undulating, in contrast to the smooth, parallel sheets inside it.

GROWTH AND FUNCTIONAL MORPHOLOGY OF KONBOSTREA KONBO
Growth Pattern

Growth sequences were restored based on well-preserved shells, and the examination of transverse
and longitudinal cross-sections of the umbones and cardinal areas. Growth lines indicate the pattern
of accretion of successive shell layers. During the early stages of the growth the shell does not show
the characteristic features of Konbostrea. Juvenile shell growth seems to occur more or less
isometrically, although the overall shell shape is extremely variable, as in typical Crassostrea. Adult
shells are here defined as those which possess the characteristics of the genus, noted above.

Juvenile left valves, 1 to 2 cm high, found attached to adults, usually have semicircular or
mytiliform outlines, with elevated umbonal areas and dorsal margins, similar to those of juvenile
shells of Crassostrea. The juvenile stages are largely composed of foliated shell material (text-fig. 6a).
Accumulation of chalky deposits inside the left valve begins when the shell height reaches about 3 to
5 cm. The young stage of the right valve is characterized by its inflated resilifer, and thin, spatular
shell which extends to the ventral margin (text-fig. 6b, c, d). Accretion of chalky deposits within the
right valve ends with the appearance of the umbonal cavity in the left valve. Up to this point the body
space rises smoothly toward the ligamental area, and there is no umbonal cavity. At this point the
ligamental area begins to recede from the body space which migrates away from it as they become
separated by the chalky deposits. This occurs when the shell height attains 15 to 20 cm.

Longitudinal cross-sections of the cardinal area of the adult left valve show that accretion of shell

150

PALAEONTOLOGY, VOLUME 29

text-fig. 7. Growth of adult Konbostrea
konbo , showing growth vector (arrow) around
the margin, and schematic form of a unit
increment of the left valve. RV, LV: right and
left valves; add. sc: adductor scar; chk: chalky
deposits; fol: foliated layer; i.tb: internal tube.
Scale bars 1 cm.

I tb AN increment of the

material occurred only around the body space. The sequence of the shell formation restored from
growth lines observed in transverse sections of the left valve (text-fig. 5) is as follows. The thin, flat
part of the valve was formed first, followed by the anterior and posterior walls which built up to
constitute the box-shaped body space. Finally the dorsal part of the body space was filled with the
chalky deposits.

Increases in shell length and maximum inflation are negligible in most specimens, once the adult
form is established. The shell frequently becomes more slender ventrally than it is dorsally. Little
change in soft body size seems to have occurred, once the adult stage was reached. In order for the
shell to grow straight, growth vectors around the entire margin must have been nearly identical,
parallel to the long axis of the shell (text-fig. 7). A single shell increment has a slipper-like form,
similar to the outline of the body space.

Growth Rate

In some bivalves such as Mercenaria , Meretrix , and Spisula the shell growth rate can be measured
directly from daily growth lines (Pannella and MacLintock 1968; Koike 1980; Jones 1983), or
it can be inferred from probable annual layers (e.g. Stenzel 1971; Chinzei 1982«). In Konbostrea , no
such reliable ‘clock' has been found to measure the growth rate of this bizarre shell.

Regular growth lines are visible in the chalky deposits around the internal tube, and in the chalky
lenses of both walls in the left valve (text-fig. 4). The interval of these growth lines measured along the
longitudinal axis of the shell, in the direction of growth, is about 0-8 to 1-2 mm. The increments are
nearly the same in the tube area and both walls, reaffirming the equality of growth rates over the
entire growth surface. The values do not vary much between younger and older shells or between
parts of an adult individual, suggesting a relatively constant growth rate throughout life, beyond the
juvenile stage. There remains a possibility, however, that the oysters adjusted their growth rate to
accord with the sedimentation rate. It is not known what kind of environmental periodicities are
reflected by these rhythmic increments. They are far larger than the daily growth increments of
ordinary bivalves, including adult living Crassostrea shells, although growth rates of chalky deposits
have not been determined. In any case, the chalky deposits and the outer shell layers must be growing
at the same rates.

The shells of C. gigas (Thun berg, 1 793) that live in Japanese waters grow up to 1 0 to 1 5 cm in height
during the first two years (0- 1 5 to 0-2 mm/day), after which growth becomes very slow. In a brackish
lagoon in Hokkaido, adult shells more than 1 5 years old as observed by fishermen, are 1 7 to 27 cm in
height in one area, while shells about 20 years old attain a height of 15 to 22 cm in another area
(Chinzei 19826). The growth rate thus varies greatly among individuals and according to locations,
even in the same habitat. Based on these figures, however, a growth rate of roughly 1 cm per year can
be estimated for adult oysters. Accordingly, I am inclined to regard the growth rate of the adult
Konbostrea as having been of the order of 1 or 2 cm per year, by comparison with that of C. gigas. This
would mean that the 1 m high individuals of Konbostrea were probably several tens to a hundred

GROWTH DIRECTION

LV

CHINZEI: ELONGATE CRETACEOUS OYSTER

151

years old. Such an age is not unreasonable. In Crassostrea species, individuals over 30 years old are
common (Galtsoff 1964). Stenzel ( 1971, P. N 1016) recorded two examples in which the annual layers
indicate ages of more than 43 and 47 years.

Mechanism of opening and closing the shell

The ligamental area is continuous with the body space during the juvenile stage, until the shell height
reaches about 1 5 to 20 cm (text-fig. 6). The ligament must have retained its function throughout this
stage of development. Thereafter, the ligamental area is separated from the body space by the chalky
deposits of the cardinal area.

Quite apart from the fact that it could no longer grow, there are other indications that the ligament
ceased to be employed to open the adult shell. As the margin of the left valve is slightly oblique to the
commissural plane, as defined by the cardinal area, closure of the shell by rotation of the valves about
the hinge is geometrically impossible. Field observations indicate that K. konbo lived with its shell
largely buried in muddy sediment, in an upright position. A small ligament located near the umbo
could surely not have been effective in opening a 1 m long shell buried in the mud. If the shell had
opened about a hinge located near the umbo, sediment would have become jammed between the two
valves. However, in all specimens examined, the valves are found tightly attached, with no exotic
material between them. The valves became fused together after the filling in of the earlier occupied
body space and became rigidly united. It is concluded that the ligament served no further purpose for
opening the adult shell and was abandoned.

The ventral margins of the valves had to gape in order for the shell to grow straight. If the valves
had been in contact, one of them would have had to curve as the shell grew, so that the entire shell
would have been curved (refer to text-fig. 7). On the other hand the shell retained a large adductor
muscle, by which the valves were evidently closed.

Judging from these features, it is postulated that the elasticity of the flat, thin, right valve was
employed to open the shell. When the adductor muscle contracted the flexible right valve bent
towards the left and the shell closed. When it relaxed the elastic valve returned to its straight, flat form
and the shell opened. The thinness and flatness of the shell are basic requirements for the elastic
bending. The shell structure of the valve, composed of outer prismatic and inner foliated layers, is
analogous to that of pinnids and other bivalves which bend their valves in closing and open elastically
(Chinzei 1982r/). It has not been ascertained whether conchiolin-rich flexible lamellae were present
along the margin of the body space as in many of the oysters (Stenzel 1971, p. N977).

Observation of well-preserved adult shells shows that the gape between the two relaxed valves at
the ventral margin is about 1 to 2 cm (text-fig. 3). As the length of the body space is approximately
30 cm, a rotation of 2° to 4 would be needed to close the valves. It is not unreasonable to suppose
that the right valve could bend to this extent.

Along the cardinal platform the two valves are tightly fused together. They are difficult to separate
on this commissural surface. The adhesion of the valves would be important to ensure bending of the
right valve near the dorsal margin of the body space. The early Jurassic bivalves Lithiotis and
Cochlearites also used the elasticity of their thin free valves to open their shells. In these genera,
reinforced fulcra controlled the bending of the valves. As its valves were tightly fused, Konbostrea did
not need to reinforce the cardinal margin of the body space to constitute a definitive fulcrum, which
indeed is lacking.

CONCLUSION: THE ADAPTATION OF KONBOSTREA TO LIFE
ON A SOFT MUDDY BOTTOM

K. konbo lived on a muddy bottom in intertidal or brackish water, burying its shell largely in the
sediment and maintaining an upright position. The characteristics of this oyster are summarized as
follows.

1 . The shell is extremely elongated with space for the soft body restricted to the ventral end of the
left valve. The right valve is thin, flat, and the same height as the left valve.

152

PALAEONTOLOGY, VOLUME 29

2. The shell is composed of a relatively thin foliated layer constituting the box-shaped outer part,
and porous chalky deposits that largely fill the interior space.

3. Adult shell growth occurred only in a ventral direction, producing a long, stick-like shell, while
the size of the soft body changed very little. Increments measured along the long axis of the shell
suggest that the growth rate was substantially constant throughout the adult stage.

4. The ligament was active only during the early stages of shell growth. Later the oyster most
probably utilized the elasticity of the thin, flat, right valve to open the shell, which was closed by
action of the adductor muscle.

All these features can be explained as consequences of the adaptation of Konbostrea to life on a soft
muddy bottom in an area of rapid sedimentation. Sediments accumulated rapidly in an intertidal or
brackish mud flat. The rate of sedimentation around oyster shells is usually very high compared with
that on the open muddy bottom because their own faecal products accumulate around the shells (e.g.
Lund 1957), and the shells exposed above the bottom act as a sediment trap (Galtsoff 1964). In order
to keep up with the rapidly accumulating sediment, Konbostrea grew dominantly in a ventral
direction, forming the stick-like shell, to maintain the soft tissues at or above the sediment surface.

The surface foliated layer provided the structural framework of the shell and gave it the strength to
withstand mechanical and chemical destruction. The inner chalky deposits are thought to have
served to fill up the interior space of the shell, maintaining the soft body close to the rising sediment
surface. Porous chalky matter was evidently adequate for this purpose, it could be deposited quickly,
and provided for economy of material. It also provided lightweight shell, which is advantageous to an
animal living on a soft bottom. The chalky deposits in living oyster shells have been thought to be
used in an analogous manner to smooth out the inner contours of the shell (Medcof 1944; Korringa
1951 ). My observation that in C. gigas these deposits appear predominately along the margin of the
shell, filling the inner depressions of the surface plication, supports this interpretation.

As chalky deposits accumulated between the ligamental area and the body space the ligament was
left behind in the mud, and lost its function. The thick umbonal part of the right valve remained
attached to the left valve, while its thin ventral margin grew upward, keeping pace with the left valve.
In this situation, use of the elasticity of the flat, thin right valve is thought to be the only possible
means by which the shell could have opened. The functional hinge, i.e. the bending point of the right
valve, was separated from the anatomical hinge, and moved upward with the soft body.

The early Jurassic bivalves Lithiotis problematica Giimbel, 1871 and Cochlearites loppianus
(Tausch, 1 890), found in the Tethyan region, are similar in basic shell morphology and shell structure
to Konbostrea (Chinzei 1982a). They are characterized by stick-like attached valves 30 to 50 cm high,
and thin, flat free valves of the same height. The body spaces are also located at the ventral ends of
these shells. Their shells are composed of compact outer layers and porous fillings of the interior.
Further, the ligament was active only during the young stage in Cochlearites, and was lacking or
vestigial in Lithiotis. These species probably used the elasticity of their thin valves to open their shells.
These features are all comparable to those of Konbostrea. However, as they were composed of
aragonite, and as Lithiotis was attached by its right valve, they are not oysters. Benini and Loriga
(1977) established a new suborder Lithiotina of the Pterioida for these bivalves. The two species are
probably related to the Isognomonidae (Chinzei 1982a) or Bakevelliidae (Seilacher 1984) of the
Pteriacea. The two species lived in a lagoonal facies, with their long shells stuck down into the mud,
keeping an upright position. Similar shell forms and shell structures of Konbostrea, Lithiotis , and
Cochlearites constitute a striking example of evolutionary convergence of different taxa, resulting
from their adaptation to similar modes of life.

The other type of shell elongation seen among the oysters is represented by cone-shaped
ecomorphs in species of Saccostrea (Stenzel 1971^ p. N1 134). The principal difference between this
cone-shaped elongation and that of the stick-shaped Konbostrea results from the manner by which
shell elongation is accomplished. In the cone-shaped shells, upward growth occurs at the ventral
margin of the ligamental area. The ligamental area and the ligament grow upward in association with
the upward migration of the soft body, as one valve is elongated. The ligament may remain active for

CHINZEI: ELONGATE CRETACEOUS OYSTER

153

opening the shell throughout the life of the animal. The morphologic consequence is a lid-like free
valve of a reduced size. Characteristic cone-shaped morphologies are seen among bivalves of diverse
taxa, such as some species of Crassostrea and other ostreid genera, the unionacean Etheria (Yonge
1953), hippuritidsand other rudists (e.g. Perkins 1969), as well as in richthofeniid (e.g. Rudwick 1961 )
and scacchinellid (Williams and Rowell 1965, p. H125) brachiopods, although the ecologic
conditions to which they adapt are not always similar.

Another common feature of these cone-shaped animals is seen in the internal structures of the
conical valves. The interior of the valve is typically largely empty, being closed off by thin, vaulted
partitions. Such structures are comparable in function to the loose chalky material of Konbostrea,
Lithiotis , and Cochlearites. These structures serve to close off the lower part of the shell and support
the soft body at the upper end of the shell.

It may not be mere coincidence that similar internal structures occur in shells with conical
elongation. This becomes apparent when they are compared with the loose chalky structure
commonly utilized by animals with stick-shaped elongation. The comparison suggests that only some
combinations of external morphology and internal structure can be employed by these animals.
Elongation between the ligamental area and the body space may only be possible for those animals
which are able to secrete chalky deposits to fill up the shell interior. For animals possessing partitions,
a stout outer structure is necessary to support these thin partitions. The growing ligamental or hinge
area of the conical animals has the function of supporting the partitions. The mode of shell
elongation seems to determine the type of internal supports developed within the shell.

Although Lithiotis and Cochlearites have reinforced commissural platforms in their attached
valves (Chinzei 1982a), they do not have partitions. On the other hand, Crassostrea nippona (Seki,
1934), which lives in open waters off the coast of Japan, often exhibits cone-shaped elongation with
internal partitions, although this species also commonly precipitates chalky deposits. The possibility
of other mechanical or physiological constraints on their morphogenesis merits further study.

Acknowledgements'. I am grateful to the colleagues in the University ofTokyo and the University of Tubingen for
their helpful discussions and support during the course of the study. In particular the discussion and
encouragement of A. Seilacher, W. E. Reif, T. Hanai, and I. Hayami are gratefully acknowledged. I owe very
much to R. D. K. Thomas of Franklin and Marshall College who reviewed the draft of this paper and gave
invaluable suggestions and comments. Thanks are due to S. Kanno of Joetsu University of Education and to I.
Obata of National Science Museum for providing information on localities of the oyster.

REFERENCES

ager, d. v. 1963. Principles of palaeoecology , 371 pp. McGraw Hill, New York, San Francisco, Toronto,
London.

benini, c. A. and loriga, c. b. 1977. Lithiotis Giimbel, 1871 e Cochlearites Reis, 1903. I. Revisione morfologica
e tassonomica. Boll. Soc. Palaeont. Italiana , 16, 15-60.

chinzei, k. 1982a. Morphological and structural adaptations to soft substrates in the Early Jurassic
monomyarians Lithiotis and Cochlearites. Lethaia, 15, 179 197.

— 19826. Palaeoecology of oysters, 1, 2. Kaseki (Fossils), Palaeont. Soc. Japan , 31, 27-34; 32, 19-27. [In
Japanese.]

galtsoff, p. s. 1964. The American oyster Crassostrea virginica Gmelin. Fishery Bull. Fish and Wildl. Serv., U.S.
Dept. Int. 64, I -480.

hayasaka, i. and hayasaka, s. 1956. On a Cretaceous species of Ostrea from Hokkaido, with special reference to
its mode of occurrence. Japan. J. Geol. Geogr. 27, 161-165.
jones, d. s. 1983. Sclerochronology: reading the record of the molluscan shell. American Scientist , 71, 384-391.
koike, h. 1980. Seasonal dating by growth-line counting of the clam, Meretrix lusoria: toward a reconstruction
of prehistoric shell-collecting activities in Japan. Univ. Mas. Bull. Univ. Tokyo , 18, 1 -120.
korringa, p. 1951. On the nature and function of ‘chalky’ deposits in the shell of Ostrea edu/is Linnaeus. Proc.
California Acad. Sci. 27, 133 158.

lund, e. j. 1957. Self-silting by the oyster and its significance in sedimentation geology. Pub/. Inst. Mar. Sci. 4,
320-327.

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MATSUMOTO, T., OBATA, I., TASHIRO, M., OHTA, Y., TAMURA, M., MATSUKAWA, M. and TANAKA, H. 1982. Correlation
of marine and nonmarine formations in the Cretaceous of Japan. Kaseki (Fossils), Palaeont. Soc. Japan, 31,
1 -26. [In Japanese.]

medcof, j. c. 1944. Structure, deposition and quality of oyster shell (Ostrea virginica Gmelin). J. Fish. Res. Board
Canada, 6, 209-216.

obata, i. and Suzuki, t. 1969. Additional note on the upper limit of the Cretaceous Futaba Group. J. Geol. Soc.
Japan, 75, 443-445. [In Japanese.]

pannella, G. and maclintock, c. 1968. Biological and environmental rhythms reflected in molluscan shell
growth. Paleonl. Soc. Mem. 2, 64-80.

perkins, b. F. 1969. Rudist morphology. In moore, r. c. (ed. ). Treatise on Invertebrate Paleontology, Part N,
Bivalvia 2, N751-N764. Geological Society of America and University of Kansas Press, Boulder, Colorado
and Lawrence, Kansas.

rudwick, M. j. s. 1961. The feeding mechanism of the Permian brachiopod Prorichthofenia. Palaeontology, 3,
450-471.

seilacher, a. 1984. Constructional morphology of bivalves: evolutionary pathways in primary versus secondary
soft-bottom dwellers. Ibid. 27, 207-237.

stenzel, H. B. 1971. Oysters. In moore, r. c. (ed.). Treatise on Invertebrate Paleontology, Part. N, Bivalvia 3,
N953-N1224. Geological Society of America and University of Kansas Press, Boulder, Colorado and
Lawrence, Kansas.

tanai, t. 1 979. Late Cretaceous floras from the Kuji District, northeastern Honshu, Japan. J. Fac. Sci. Hokkaido
Univ.Ser.4, 19,75-136.

taylor, I. d., Kennedy, J. w. and hall, A. 1969. The shell structure and mineralogy of the Bivalvia. Introduction,
Nuculacea-Trigonacea. Bull. Br. Mus. nat. Hist. (Zook), Suppl. 3, 1-125.

williams, a. and rowell, d. j. 1965. Morphology. In moore, r. c. (ed.). Treatise on Invertebrate Paleontology,
Pt. H, Brachiopoda 1, H57-H138. Geological Society of America and University of Kansas Press, Boulder,
Colorado and Lawrence, Kansas.

yonge, c. m. 1962. On Etheria elliptica Lam. and the course of evolution, including assumption of
monomyarianism, in the Family Etheriidae (Bivalvia, Unionacea). Phil. Trans. Roy. Soc. B, 244, 423-458.

Typescript received 18 February 1985
Revised typescript received 12 May 1985

KIYOTAKA CHINZEI
Geological Institute
University of Tokyo
Hongo, Tokyo 1 13, Japan

OVICELLS IN THE PALAEOZOIC BRYOZOAN
ORDER FENESTRATA

by ADRIAN J. BANCROFT

Abstract. The occurrence and morphology of fenestrate ovicells is reviewed and ovicells are described for the
first time in Pennirelepora. Four ovicell types are recognized and the considerable variation in morphology, size,
position, and intra-colonial abundance of ovicells at generic level is related to variation in the morphology of
autozooecial chambers, proximity of autozooecia, and the number of autozooecial rows on branches and
dissepiments. Type A ovicells from large globose distentions to gonozooecia, are intra-colonially few in number
and occur in Fenestella , Hemitrypa , and Pennirelepora ; Type B ovicells occur in Septatopora , and form shallow
hemispherical depressions at the proximal rims of autozooecial apertures and are connected to the lower
vestibular regions of adjacent gonozooecia by an auxiliary tube; Type C ovicells occur in Synoc/adia ,
Acanthocladia, and Thamniscus , and form hemispherical depressions at the proximal rims of autozooecial
apertures and are intra-colonially very abundant; Type D ovicells are extrazooidal and occur in Polypora ,
ovicells are located on dissepiments and are linked to gonozooecia by a system of canal-like structures traversing
branches and dissepiments, several gonozooecia shared an ovicell. Ovicell morphology may be of phylogenetic
significance and of value at higher taxonomic rank in fenestrates.

Ovicells are chambers for the brooding of embryonic products from gonozooecia prior to their
release into the sea. It is only recently that ovicells have been recognized and described in Palaeozoic
fenestrate Bryozoa (Class Stenolaemata Borg 1926; Order Fenestrata Elias and Condra 1957).
Tavener-Smith (1966), Engel (1975), Stratton (1975, 1981), and Southwood (1985) have shown that
a considerable variety exists in the morphology of ovicells and that they constitute the most diverse
form of polymorphism in the Fenestrata.

Fenestrate ovicells are rare and Stratton (1975, 1981) suggested that in the majority of taxa
embryonic products were either immediately discharged into the sea, or else brooded internally in the
coelom or in external organic ovisacs which are not preserved fossil. He also partly attributed the
paucity of fenestrate ovicells to low preservation potential. However, their paucity may be also
explained by the fact that many taxa have been established on the basis of single, small, often poorly
preserved colony fragments. Considering the rarity of zoaria containing ovicells in taxa known to
possess ovicells, it seems probable that ovicells will be discovered in a number of these poorly
described forms when additional comparative material becomes available.

The repositories of all the cited and figured material are: British Museum (Natural History),
BMNH; Durham University Geology Department, Southwood Collection, DUGD, SC; Field
Museum of Natural History, Chicago, Illinois, USA, FMNH.

FENESTRATE OVICELLS

The fenestrate ovicell is distal lo the autozooecial chamber, similar to ovicells described in cheilostome
gymnolaemates, and the dilated parts of gonozooecia in cyclostome stenolaemates (Borg 1926;
Ryland 1970). In fenestrates ovicells belong to a single zooid (the gonozooid), with one exception
where ovicells may be regarded as extrazooidal and apparently served more than one zooid.

Four different types of ovicellular structures are recognized in fenestrates and these correlate with
variations in the morphology of autozooecial chambers and the proximity and number of rows of
autozooecia on branches. More than one genus may possess the same ovicell morphology. For ease
of description and comparison the different types are here designated A, B. C, and D.

(Palaeontology, Vol. 29, Part 1, 1986, pp. 155-164, pi. 19.]

156

PALAEONTOLOGY, VOLUME 29

Type A

Tavener-Smith (1966) and Stratton (1975) described inflated calcified structures incorporating the
distal portions of autozooecial chambers which they interpreted as ovicells in the fenestellids
Fenestella Lonsdale and Hemitrypa Phillips. Tavener-Smith first described this type of ovicell in three
species: H. hibernica M‘Coy, F. cf. fanata Whidborne, and F. cf. delicatula Ulrich from Lower
Carboniferous (Asbian) limestones of Carrick Lough, County Fermanagh, Northern Ireland.
Stratton described similar structures in Fenestella sp. from the Middle Devonian (Eifelian), North
Vernon Limestone, Indiana, USA. Earlier workers have also described comparable structures in
Fenestella (e. g. Hall and Simpson 1887, p. 105, pi. 45, fig. 23, pi. 47, fig. 24; Nikiforova 1938, pp. 245,
248, 251; Elias and Condra 1957, p. 131).

In all these forms the gonozooecium is directly connected, by a short vestibular region, to the
ovicell above which forms a large globose distention of the gonozooecial chamber (PI. 19, fig. 1; text-
fig. 1a, b). In H. hibernica ovicells range in diameter from 0-46 mm to 0-50 mm (Tavener-Smith 1966,
p. 195 stated that ovicells in H. hibernica have an average diameter of 0-28 mm, this is presumably a
typographical error), and in F. cf. fanata the average dimensions of ovicells are length 0-67 mm and
width 0-58 mm (Tavener-Smith 1966, p. 191). The ovicells described in Fenestella sp. by Stratton
(1975) are significantly smaller, with an average diameter of 0-29 mm.

Tavener-Smith (1966) also described the occurrence of partially preserved fragile calcified roofs to
ovicells in Fenestella and Hemitrypa species, with an opening (ooeciopore) in the crests through
which the larvae were presumably liberated (PI. 19, fig. 2; text-fig. 1b). In most of Tavener-Smith’s
material the ovicells are partly weathered with the fragile roof of the ovicell missing revealing the
smooth and well-rounded interior (PI. 19, fig. 1). The basal area of these ovicells is usually depressed
into the obverse branch surface and their cyst-like character locally increases the height of the branch
(PI. 19, fig. 3; text-fig. 1a). Because of their large size ovicells commonly affect the development of
adjacent autozooecia and they may even extend across the entire width of a branch causing its
margins to bulge (PI. 19, fig. 1).

The intra-colonial abundance of ovicells is very low compared to the number of normal
autozooecia, and they commonly occur in isolation and are apparently randomly positioned (PI. 19,
figs. 4 and 5). As Tavener-Smith (1966) noted the morphology of ovicells in Fenestella and Hemitrypa
species bears a strong resemblance to Recent cyclostome gonozooecia described by Borg (1926). This
resemblance, together with the relatively large size of ovicells in fenestellids, suggested to Tavener-
Smith that polyembryony which occurs in the gonozooids of Recent cyclostomes may also have
occurred in fenestellids. (Polyembryony or embryonic fission is the asexual division of the primary
embryo into secondary embryos or even tertiary embryos, all presumably with the same genetic
make-up.)

During a recent revision of British and Irish Carboniferous fenestrate Bryozoa, study of several

EXPLANATION OF PLATE 19

(Specimens figured 1-5 were also figured by Tavener-Smith 1966, pi. 25.)

Type A ovicells: Figs. I and 5, Hemitrypa hibernica M'Coy, BMNH PD. 4493, 1, showing ovicells forming
distentions on top of gonozooecial vestibular regions (one vestibule is arrowed), x 29. 5, distribution of
ovicells on colony fragment, x 12.

Figs. 2, 3, 4, Fenestella cf. fanata Whidborne. 2, BMNH PD. 4487, ooeciopores in the crest of two ovicells, x 52,
3, BMNH PD. 4486, increase in branch height due to ovicell, x 66. 4, BMNH PD. 4486, distribution of ovicells
on colony fragment, x 15.

Figs. 6 and 7, Penniretepora spinosa (Young and Young) BMNH PD. 6280. 6, obverse surface detail and
showing ovicell on top left lateral branch, x 30. 7, detail of ovicell, x 140.

Figs. 8 and 9, Penniretepora sp. BMNH PD. 6281 . 8, obverse surface detail and showing ovicells, x 22. 9, detail
of ovicell on mainstem, also showing top of vestibular region of gonozooecium (arrowed) at base of
ovicell, x 1 50.

SEMs.

»*

PLATE 19

BANCROFT, bryozoan o vice I Is

158

PALAEONTOLOGY, VOLUME 29

species of the acanthocladiid genus Penniretepora d'Orbigny has, for the first time, revealed the
occurrence of ovicells in this genus. Ovicells occur in two species, one assigned to P. spinosa (Young
and Young), the other to an undescribed form, Penniretepora sp. The ovicells in Penniretepora are
comparable both in morphology and intra-colonial abundance to type A ovicells previously
described in species of Fenestella and Hemitrypa.

Penniretepora spinosa (Young and Young, 1874)

Plate 19, figs. 6 and 7

Remarks : P. spinosa (Young and Young) was originally described as a variety of Glauconome stellipora Young
and Young (1874), but it is proposed to elevate the variety to species level.

Material : BMNH PD. 6280; Lower Limestone Group, Hosie Limestones (Visean, Brigantian), Hairmyres, East
Kilbride, Scotland.

Ovicell Description: One small colony fragment has been found on which a single ovicell is situated on a lateral
branch (PI. 19, figs. 6 and 7). The ovicell is relatively large compared to branch width (length 0-21 mm, width
0T6 mm), with its inner margin abutting the median carina and outer margin causing the branch to bulge
considerably. However, the ovicell does not disturb the disposition of adjacent apertures. The base of the ovicell
is depressed relative to the obverse branch surface and is situated centrally over the vestibular region of the
gonozooecium. It also has a thick rim-like perimeter which is partially weathered, but it is not possible to
determine whether this extended as a calcified cover during life.

Penniretepora sp.

Plate 19, figs. 8 and 9

Material ; BMNH PD. 6281; shales above the Main Limestone (Namurian, Pendelian -Arnsbergian), Hurst,
North Yorkshire.

Ovicell Description: Again only one small colony fragment has been found on which five ovicells occur randomly
situated on lateral branches and the mainstem (PI. 19, figs. 8 and 9). These ovicells form fairly large oval cysts
(length 0-30 mm, width 0-20 mm) and their bases are markedly depressed into the obverse branch surface (PI. 19,
fig. 9). Their inner margins abut on to the median carina of branches and outer margins cause branch margins
to bulge, but they do not affect the disposition of adjacent autozooecial apertures. The ovicells have low but
prominent, slightly elevated rim-like perimeters; they are, however, partially weathered and it is not possible to
ascertain whether these rims extended over the ovicell as a calcified cover during life. Ovicells are situated
centrally above the vestibular region of gonozooecia (PI. 19, fig. 9).

Type A

In taxa from which type A ovicells are described the actual number of colonies possessing them is very
low. Type A ovicells are known from only single colony fragments in two species of Penniretepora,

text-fig. 1. Type A ovicells: a (redrawn from Tavener-Smith 1966, text-fig. 1a), Fenestella cf. fanata

Whidborne, showing gonozooecium with large cyst-like ovicell, x 26. b (redrawn from Stratton 1975, fig. 3),
transverse section through a branch in Fenestella sp. showing ovicell with ooeciopore, x 230.

Type B ovicells: c (redrawn from Engel 1975, text-fig. 1 b), Septatopora acarinata (Crockford), showing ovicell
at proximal extremity of autozooecial aperture, x 60. d (redrawn from Engel 1975, text-fig. 1a), Septatopora
flemingi Engel, detail as for c, x 75.

Type C ovicells E, F, Synocladia virgulacea (Phillips) (redrawn from Southwood 1985, fig. 5a, b). E, oblique
tangential section through a branch, points 1-5 correspond to the level in the branch shown in f, x 50.
F, longitudinal section through an autozooecium with ovicell, x 50.

Type D ovicells: G, Polypora shumardii Prout, showing canal pathways meandering over the branch surface
and ovicell situated on dissepiment, x 60.

BANCROFT: BRYOZOAN OVICELLS

159

D

Type C

Ovicell

Type D

160

PALAEONTOLOGY, VOLUME 29

and in all fenestellids type A ovicells have been found to occur at only one locality per species. This
anomalous distribution cannot be explained satisfactorily by the fact that only the colonies at these
localities attained a brooding capacity before they died, nor by the improbability of finding rare
ovicells as colonies are normally found in a fragmented state. It may be possible that environmental
factors played an important part in determining the fertility of colonies within species. This
suggestion is supported by two lines of evidence. First, ovicells described in three taxa by Tavener-
Smith (1966) all came from the same locality, and secondly, ovicell bearing zoaria are quite common
in these taxa from this locality.

Type B

Engel (1975) described hemispherical ovicellular depressions situated at the proximal rims of
autozooecial apertures in two species of the Carboniferous fenestrate Septatopora Engel, from
eastern Australia. The ovicells form very shallow, well-rounded depressions and are relatively small,
being about 01 mm in diameter in S. acarinata (Crockford) and 0-2 mm in diameter in S.flemingi
Engel. They are connected to the lower vestibular regions of adjacent gonozooecial chambers by an
auxiliary tube which is present in every autozooecium (text-fig. lc, d). Ovicells are quite common in
zoaria of S. acarinata , but are scarcer in S. flemingi and are of a similar abundance to type A ovicells.

Engel (1975, p. 576) suggested that the auxiliary tube was used for transferring fertilized embryos
from the gonozooecium to the ovicell where they were incubated prior to their final release. As Engel
stated this would help explain the coincidence of auxiliary tube openings with the hemispherical
depressions on the branch surface adjacent to the proximal rim of some autozooecial apertures. In
Engel’s material the ovicells simply form depressions; there is no evidence of any calcified roof.

The method of transfer of fertilized eggs from the gonozooecium through the auxiliary tube is
conjectural. In some Recent cheilostome gymnolaemates the transfer of fertilized eggs to distally
positioned brooding cavities requires considerable movement and manipulation by the tentacle
crown of the autozooid. As Engel (1975) stated this is clearly a process not possible from the base of
the vestibule in Septatopora.

Engel (1975, p. 576) also suggested that the reproductive function of the auxiliary tube was
combined with an alimentary function. Autozooecial apertures are septate in all species of
Septatopora and the occurrence of septa would obviously greatly restrict the ability of the polypide to
be protruded from the zooecial chamber. In their fully protruded position the tentacles would have
been placed between the septa, and the mouth must have been located beneath the small central
opening, with the base of the lophophore contained within the vestibule. In Septatopora the anus,
which in ectoproct bryozoans is situated outside the lophophore, must have been contained within
the vestibule and Engel suggested that the auxiliary tube had a sanitary function in providing an
outlet for faeces. The fact that every autozooecium, including those lacking ovicells, in all species of
Septatopora possesses an auxiliary tube supports such a non-brooding function, but does not
preclude an additional role in brooding.

Type C

Southwood (1985) described the occurrence of possible internal ovicells in three Upper Permian taxa
from the Middle Magnesian Limestone reef facies of north-east England, the acanthocladiids
Synocladia virgulacea (Phillips) and Acanthocladia sp., and the thamnisciid Thamniscus sp. The
ovicells are morphologically alike in all three taxa. They form small rounded cavities as distal
extensions of autozooecial vestibules and are possibly contained within branches according
to Southwood. Some of Southwood’s material is dolomitized with autozooecial chambers and
ovicellular cavities preserved as three dimensional casts with the original calcite bryozoan skeleton
replaced by dolomite or removed entirely (text-fig. 2a, b).

Tangential sections show the occurrence of a small circular cavity situated at the proximal
extremities of autozooecial vestibular regions. While deeper tangential sections show a line of skeletal
material separating the cavity from the vestibular region of autozooecia, in shallow sections this line
disappears and the ovicellular cavity and vestibular spaces are continuous (text-fig. 1e, f). Although

BANCROFT: BRYOZOAN OVICELLS

161

text-fig. 2. Type C ovicells: a, b, Synocladia virgulacea (Phillips), DUGD, SC. MP.18 (reproduced from
Southwood 1985, fig. 6). A, cast preservation of abundant ovicells (one ovicell is arrowed), x 13, b, detail
of ovicells, x 52. c, d, Thamniscus octonarius Ulrich (reproduced from Ulrich 1890, pi. 62). c, arrangement
of autozooecial apertures on obverse surface, x 9. d, obverse surface detail showing rounded ovicellular
depressions at proximal extremity of every autozooecial aperture; some depressions have low elevated
rims, x 35.

Type D ovicells: E, Polypora shumardii Prout (reproduced from Stratton 1981, pi. 1). FMNH UC14016
F15-16, showing canal pathways traversing branches(a) and ovicells situated on dissepiments(b), x 5.

All figures except c and d are SEMs.

longitudinal sections show a small rounded concave depression proximal to autozooecial apertures,
these are not well defined and Southwood suggested that their occurrence at the zoarial surface may
be due to the removal of some of the bryozoan skeleton. However, it may be possible that these
ovicells formed features on the zoarial surface, and are morphologically similar to type b ovicells in
Septatopora which also form shallow rounded depressions at the zoarial surface.

Ulrich ( 1 890, p. 61 1 , pi. 62, fig. 7a, b) described and figured comparable structures in the American
Carboniferous fenestrate T. octonarius Ulrich. These are definitely external features and may also be
interpreted as ovicells. On the obverse surface the peristomial rim of autozooecial apertures is
incomplete, and from this a very shallow depression emanates. In some cases a low rim-like structure
extends around the perimeter of the depressions from the incomplete proximal extremities of
autozooecial apertures (text-fig. 2c, d).

162

PALAEONTOLOGY, VOLUME 29

Identical structures to these have been found recently in an Upper Permian species of
Acanthocladia from the Lower Magnesian Limestone of County Durham (Southwood, pers. comm.).
In T. octonarius and Acanthocladia although a low rim-like structure occurs around the perimeter of
many ovicells there is no indication of this rim having extended in life to form a roof over cavities.
Roofs of type C ovicells were possibly uncalcified during life, as were those of type B ovicells.

Ovicells in most of these taxa are of fairly similar diameter; those of T. octonarius being
approximately 0-20 mm, while those in Synocladia virgulacea , Acanthocladia sp., and Thamniscus sp.
are about 016 mm in diameter. This is comparable in size to type B ovicells in Septatopora flemingi
(0-20 mm).

The striking feature of ovicells in Synocladia virgulacea is their abundance (Southwood 1985).
They can be found in every autozooecium of some colony fragments but their distribution can also be
sparse and irregular and they may show a weak clustering into groups (text-fig. 2a). In T. octonarius
ovicells are also very abundant with every autozooecium figured by Ulrich (1890) possessing one,
while in Acanthocladia sp. and Thamniscus sp. ovicells are possibly less abundant though still more
abundant than in Septatopora species.

Type B and C ovicells are very different from type A ovicells in their morphology, size, and within-
colony abundance. Southwood (1985) suggested that if Tavener-Smith’s (1966) conclusions are valid
about the large size of ovicells in Fenestella and Hemitrypa being evidence of polyembryony, then it is
possible that polyembryony did not occur in the small sized ovicells of Synocladia virgulacea.
Southwood also suggested that because almost every autozooecium in S. virgulacea has an ovicell the
zooid was an autozooid that did not degenerate during brooding (unlike gonozooids of Recent
cyclostomes) and that it may have been possible for an embryo to develop in an ovicell at the same
time as the zooid was feeding. Southwood made particular reference to the aspect of these ovicells
being reminiscent of entozooidal ovicells in some cheilostome Bryozoa (Ryland 1970).

Type D

These were described by Stratton (1981) in Polypora shumardii Prout from the Jefferson Limestone
(Mid Devonian) Falls of Ohio, Indiana-Kentucky, USA. Stratton described a system of canal-like
structures traversing branches and dissepiments. The canals lead from autozooecia interpreted to be
gonozooecia, to inflated bowl-like depressions located on the dissepiments, interpreted as ovicells
(text-figs. 1g, 2e). Several autozooecia may be situated alongside each meandering canal (text-
fig. 1g). Autozooecial apertures bordering canals have normally developed peristomes on their
margins opposite the canals but reduced peristomes within the canals. Apertures situated entirely
within canals have very poorly developed peristomes. Ovicells are of moderate size, about 0-30 mm in
diameter, and open towards fenestrules.

Stratton’s material was silicified, and although he observed that some of the canals were partly
covered by a thin silicified layer he concluded that the canals and ovicells may not have been enclosed
by a calcitic cover during life. Stratton suggested that the canals provided a pathway from
gonozooecia to ovicells, enabling the transport of embryonic products to ovicells. He also suggested
that because of the reduced peristomes of several autozooecia along a canal, the canals served more
than one gonozooecium. This is a unique phenomenon in fenestrate reproductive strategy, in that this
type of ovicell may be regarded as extrazooidal.

Canal and ovicell bearing zoaria were fairly common in Stratton’s material with approximately
half of the total population examined possessing them. Stratton considered about 20% of the total
number of autozooecia on canal-bearing zoaria to be gonozooecia on the basis of their position in
relation to the canals and the presence of a reduced peristome. As he stated it is conjecture whether or
not all gonozooids along a single canal were active at one time, but the presence of reduced peristomes
and their location along canals may suggest that each gonozooid was probably active at least once.
The canals would have enabled the transportation of fertilized eggs to ovicells on dissepiments
without significantly disturbing adjacent autozooecia. Considering the close proximity and number
of autozooecial rows on branches severe disruption would have occurred if the zooecial walls had

BANCROFT: BRYOZOAN OVICELLS

163

expanded for brooding in situ, i.e. if large cyst-like ovicellular structures had developed on branch
surfaces.

CONCLUSIONS

The diverse morphological variation exhibited at generic level by fenestrate ovicells in their size,
position, and intra-colonial abundance is related to variations in autozooecial chamber morphology,
proximity of autozooecia, and the number of autozooecial rows on branches.

In the type A ovicells of Fenestella, Hemitrypa, and Penniretepora with only two rows of
autozooecia on branches there was ample space for the development of relatively large cyst-like
ovicellular structures, incorporating the distal portion of vestibular regions of gonozooecia, on the
obverse surface of branches. In taxa with several rows of autozooecia on branches and dissepiments
the development of such structures would have severely interfered with the feeding function of
autozooecia because of their closer proximity and greater number of autozooecial rows. Different
types of incubation structures were developed in some forms. Type B ovicells in Septatopora and
type C ovicells in Synocladia , Acanthocladia , and Thanmiscus form small hemispherical depressions
situated on the zoarial surface at the proximal extremities of autozooecial apertures and are usually
significantly more abundant intra-colonially than type A ovicells. In the type D ovicells of P. shumardii
a unique strategy was developed. Ovicells are situated on non-poriferous dissepiments with
gonozooecia linked to ovicells by a system of canal pathways at the zoarial surface, and several
gonozooecia seemingly shared a single ovicell.

Only type A ovicells described in Fenestella , Hemitrypa , and Penniretepora bear close resemblance
to living cyclostome gonozooecia. Contrary to Tavener-Smith’s (1966, p. 196) and Stratton’s (1975,
p. 175) suggestion that fenestrate ovicell morphology suggests a close relationship with cyclostome
stocks, recent descriptions of fenestrate ovicellular structures by Stratton (1981) and Southwood
(1985) show that on the whole the morphological similarity of fenestrate ovicells and cyclostome
gonozooecia is no better than between fenestrate and cheilostome ovicells. Tavener-Smith (1966,
p. 196) even noted the superficial resemblance of the external morphology of ovicells in Fenestella
and Hemitrypa with peristomial ovicells in certain cheilostome genera. There is no suggestion,
however, that fenestrate ovicells contradict the closer affinities of fenestrates to cyclostomes than to
cheilostomes demonstrated by various other morphological evidence.

Stratton (1981, p. 881 ) stated, without giving reasons, that although the morphology and structure
of ovicells he described in P. shumardii was different from those described by Tavener-Smith (1966)
and Stratton (1975), in Fenestella and Hemitrypa , the methods of incubation were probably
consistent among all these forms. However the morphological variety shown by fenestrate ovicells
may suggest that different methods of embryonic development and incubation occurred.

It is not reasonable to infer polyembryony in fenestrates on the grounds of ovicell morphology
alone, for it has yet to be investigated whether all large gonozooids in living cyclostomes undergo
polyembryony in their reproductive cycles (Boardman et at. 1983, p. 108). If this does prove to be the
case only then can it be reasonably assumed that fenestrate taxa with comparable ovicellular
structures may have undergone polyembryony. Sounder basis for regarding fenestrates as having
been polyembryous is provided by the phylogenetically closer affinities of fenestrates with
cyclostomes than with cheilostomes, and by the occurrence of inter-colony fusion (homosyndrome)
in fenestrates, suggesting that genetically identical larvae resulting from polyembryony may have
occurred (see McKinney 1981).

Ovicells can be very useful in bryozoan taxonomy and at species level they are critical to taxonomic
determinations in some groups, e.g. many cheilostomes and cyclostomes. The morphology of
bryozoan ovicells may also be of phylogenetic significance and of value at high taxonomic rank,
though their application is largely uninvestigated (Viskova 1981).

Ovicell morphology is almost identical in the fenestellids Fenestella and Hemitrypa and the
acanthocladiid Penniretepora while both autozooecial chamber and ovicell morphology are nearly
identical in the acanthocladiids Synocladia and Acanthocladia and the thamnisciid Thanmiscus. If

164

PALAEONTOLOGY, VOLUME 29

these similarities are important phylogenetically then conventional taxonomic arrangements of the
fenestrates may require some revision.

Acknowledgements. I thank Dr G. P. Larwood and Mr D. A. Southwood, Department of Geological Sciences,
University of Durham, for critically reading an early draft of this paper, and Dr P. D. Taylor, Department of
Palaeontology, British Museum (Natural History), for reviewing a revised draft. This work was carried out
during the tenure of a Natural Environment Research Council research studentship at the Department of
Geological Sciences, University of Durham.

REFERENCES

boardman, r. s. et al. 1983. Bryozoa. In robison, r. a. (ed.). Treatise on Invertebrate Palaeontology. Part G,
Vol. 1, 625 pp.

borg, f. 1926. Studies on Recent cyclostomatous Bryozoa. Zool. Bidr. Upps. 10, 181-507.
elias, m. k. and condra, G. e. 1957. Fenestella from the Permian of West Texas. Mem. Geol. Soc. Am. 70, 158 pp.
engel, b. a. 1975. A new ?bryozoan from the Carboniferous of Eastern Australia. Palaeontology , 18, 571-605.
hall, j. and simpson, G. b. 1887. Corals and Bryozoa: text and plates containing descriptions and figures from the
Lower Heldberg, Upper Heldberg and Hamilton Groups. Natural History of New York State. Geol. Surv.
Albany. 298 pp.

mckinney, F. K. 1981. Intercolony fusion suggests polyembryony in Paleozoic fenestrate bryozoans.
Paleobiology , 7, 247-251.

Nikiforova, a. i. 1938. Types of Carboniferous bryozoans of the European part of the U.S.S.R. In. Acad. Sci.
USS R. 4, 290 pp.

ryland, j. s. 1970. Bryozoans , 175 pp. Hutchinson and Co., London.

southwood, d. a. 1985. Ovicells in some Fenestrata from the Permian of N. E. England. In nielsen, c. and
larwood, G. p. (eds.). Bryozoa Ordovician to Recent. Olsen and Olsen, Fredensborg.
stratton, j. f. 1975. Ovicells in Fenestella from the Speed Member, North Vernon Limestone (Eifelian, Middle
Devonian), in Southern Indiana, U.S.A. Doc. Lab. Geol. Sci. Lyon. HS. 3, (fasc. /), 169-177.

1981. Apparent ovicells and associated structures in the fenestrate bryozoan Polypora shumardii Prout.
J. Paleont. 55, 880-884.

tavener-smith, r. 1966. Ovicells in fenestrate cryptostomes of Visean age. J. Paleont. 40, 190-198.
ulrich, e. o. 1890. Paleontology of Illinois Paleozoic Bryozoa. Bull. Geol. Surv. Illinois , 283-688.
young, J. and young, j. 1874. New Carboniferous Polyzoa. Q. Jl Geol. Soc. Lond. 30, 681-683.
viskova, l. a. 1981. Brood chambers in Recent and fossil marine bryozoans. Paleont. J. 15 (4), 35-52.

ADRIAN J. BANCROFT

Department of Geology
Trinity College
Dublin 2, Eire

Typescript received 22 March 1985

NEW TRIASSIC SPHENODONTIDS FROM
SOUTH-WEST ENGLAND AND A REVIEW OF
THEIR CLASSIFICATION

by N. C. FRASER

Abstract. Two new genera of Triassic sphenodontid are described. Sigmala sigmala gen. et sp. nov. and Pele-
cymala robustus gen. et sp. nov. occur in fissure deposits in Cromhall Quarry, south Gloucestershire. They are
based entirely on dissociated jaw elements. Five sphenodontid genera have now been described from this locality
and they permit a review of sphenodontid systematics. Based principally on dental morphology, an updated
classification of the Sphenodontidae is offered. Five subfamilies are recognized: namely the Polysphenodontinae,
Brachyrhinodontinae, Sphenodontinae, Homoeosaurmae, and Eilenodontinae.

There has been a recent regeneration of interest in the Mesozoic herpetofaunas of south-west
Britain (Marshall and Whiteside 1980; Whiteside and Robinson 1983; Fraser and Walkden 1983;
Benton 1984a) with the concomitant description of a number of new genera and species (Evans 1980,
1981; Fraser 1982; Crush 1984; Fraser and Walkden 1984; Kermack 1984). Of the various localities
known to contain vertebrate remains, perhaps Cromhall Quarry, south Gloucestershire (ST 704 916),
has the largest range of tetrapods and at present the list of species stands at fourteen, of which six are
sphenodontids. Four of the sphenodontids are relatively abundant and have been recorded from
other localities. These are Planocephalosaurs robinsonae, Clevosaurus hudsoni , C. minor , and a third
genus currently being described by D. I. Whiteside, which will be referred to as Sphenodontid X. The
remaining two sphenodontids are known only from completely dissociated jaw bones and form the
subject of this paper.

Although it is generally not desirable to erect new genera and species solely on the basis of one
or two isolated bones, in this instance it is felt that little further material will be recovered from
the Cromhall deposits, as a large quantity of sediment has already been systematically processed
from all accessible levels of the fissure sediments. In addition one species has already been named
in a previous discussion on the palaeoecology of the Cromhall assemblages (Fraser and Walkden
1983), and it is therefore necessary to document fully these forms and give them proper taxonomic
treatment.

SYSTEMATIC PALAEONTOLOGY

The fifth most abundant sphenodontid in the Cromhall fauna was provisionally named Sigmala
sigmala (Fraser and Walkden 1983). It will be formally described here as a new genus and species.
Whilst not a common form the dentition is quite characteristic and has enabled the positive identifica-
tion of the maxilla, dentary, and palatine, including juvenile specimens. No other elements have
been recognized, probably for one or both of two reasons. First, the genus is in any case relatively
rare; consequently only a few fragments of other bones are likely to be present in the residues:
these may well be unrecognizably broken and worn. Secondly, since it would appear that skeletal
morphology is quite uniform within the Triassic sphenodontids, the structure of other elements may
resemble those of the similar-sized and much more abundant genus, Clevosaurus. In this case,
polishing and general post-mortem attrition may have obliterated any distinguishing features that
might be expected.

IPalaeontology, Vol. 29, Part 1, 1986, pp. 165-186, pi. 20.|

166

PALAEONTOLOGY, VOLUME 29

text-fig. 1. Sigmala sigmala gen. et sp. nov. Holotype, right maxilla, AUP no. 11083,
in a, lateral and b , medial views.

Class REPTILIA

Subclass diapsida Osborn 1903
Order sphenodontida Cope 1 890
Family sphenodontidae Cope 1890
Genus sigmala gen. nov.

Species Sigmala sigmala sp. nov.

Etymology. Description of the flexure observed in the lower jaw when viewed dorsally (Gr. Sigma ; L. mala jaw).

Diagnosis. A sphenodontid with maxilla approximately 13 mm long and bearing a distinct extension
of bone on its anterior margin; all teeth acrodont with an approximate triangular form in lateral
aspect; anteriorly the marginal teeth are small and alternate in size in the juvenile, but are entirely
worn down to the bone in mature specimens; no successional teeth on either the maxilla or dentary;
approximately eight to ten additional teeth in each jaw quadrant which bear rudimentary anterior
and posterior flanges on the dentary, but only posterior flanges on the maxilla; all additional teeth
generally of uniform size; both maxilla and dentary are broadened dorsoventrally; dentary exhibits

FRASER: TRIASSIC SPHENODONTIDS

167

a distinct sigmoid flexure in dorsal aspect; discrete lateral wear facets on dentary; high coronoid
process; palatine with a single row of seven or eight obtusely conical teeth.

Holotype. AUP no. 1 1083, right maxilla.

Paratypes. AUP no. I 1082, left dentary; AUP no. 1 1084, left palatine.

Type locality. Karstic fissures in Dinantian limestones. Cromhall Quarry, south Gloucestershire.

Horizon. Upper Triassic.

Description. The maxilla (PI. 20, fig. 1 ; text-fig. 1 ) is a deep hone with an extensive dorsal process anterior to the
orbit. A curious feature of the element is its contact with the premaxilla and the posterior boundary of the
external naris. An examination of the medial surface of the bone (text-fig. 16) reveals a pronounced facet for
a premaxillary process just dorsal to the tooth row, but the elongated flap of bone immediately above the
premaxillary facet has not been previously observed in any sphenodontid. This lappet (text-fig. 1 a. ant.l.) of bone
lacks any obvious facet either for the premaxilla or a descending process of the nasal. It seems unlikely that the
posterior margin of the naris would have had such a complex outline; more probably either the premaxilla or
nasal, or both, marked the posterior boundary of the external naris and were overlapped by this maxillary
lappet. The dorsal process of the maxilla bears a well-defined medial facet where it overlapped the prefrontal.
Mature individuals exhibit a broad flange of bone ventral to the orbit which on the medial surface displays facets
for the jugal and palatine (text-fig. 16, j.f. and pal. I'.). The palatine facet is marked by the characteristic palatine
foramen. Ventral to the extensive jugal facet is a further rugosity against which the ectopterygoid abutted.

Anteriorly the maxilla bears approximately ten small teeth representing the remanent hatchling dentition. In
the adult these teeth are invariably worn to the bone, but this series shows an alternation in tooth size in
immature individuals. There were apparently no maxillary successional teeth. More posteriorly a mature
individual normally has between eight and ten larger additional teeth which bear slight posterior flanges, but
these are not as extensive as those of Clevosaurus and Homoeosaurus. The last three or four teeth of the addi-
tional series may be unflanged and somewhat smaller than the others. The additional teeth display extensive

s. d

2'0 mm

text-fig. 2. Sigmala sigmala gen. et sp. nov. a , paratype, left dentary, AUP no. 11082, in
dorsal view. 6, right dentary, AUP no. 11364, in lateral view.

168

PALAEONTOLOGY, VOLUME 29

den

2-0 mm

text-hg. 3. Sigmala sigmala gen. et sp. nov.
Paratype, left palatine, AUP no. 11084, in dorsal
aspect.

lingual wear facets and mature individuals have a broad layer of secondary dentine on the lateral surface of the
maxilla (text-fig. la, s.d.).

The dentary (PI. 20, tigs. 2 and 3; text-fig. 2) is approximately 20 mm long, deep and with a high coronoid
process. Anteriorly there is a stout jaw symphysis and posteriorly the element extends for some distance
posterior to the coronoid process. Medially there is an open meckelian groove but with no indications of facets
for a splenial. In dorsal view the dentary displays a slight S-shaped flexure (text-fig. 2a). There are approximately
ten small teeth anteriorly which show some alternation in size. In mature individuals these teeth are completely
worn to the bone and, as a result of the complete absence of successional teeth, there is an ‘edentulous’ anterior
region. There are usually about eight additional teeth— each with small anterior and posterior flanges— and the
posterior teeth are set slightly medial to the coronoid process (text-fig. la). Unlike other sphenodontids the
additional teeth tend not to exhibit a progressive increase in size caudad. Well-defined lateral wear facets were
caused by the precise occlusion of the maxillary dentition, and these facets extend well beyond the bases of the
teeth and deep into the bone (text-fig. 2b). Wear facets on the lingual surfaces of the mandibular teeth are
evidence of the influence of an enlarged tooth row on the palatine. In one example of a juvenile dentary (PI. 20,
figs. 4 and 5) an additional tooth shows the process of ankylosis at the posterior end of the ramus. This tooth
displays a degree of pleurodonty, lying both ventral and medial to the summit of the jaw ramus (PI. 20, fig. 5). In
a mature individual it would become more firmly attached by cementum and secondary dentine. Even in those
juveniles in which the full complement of additional teeth had yet to be attained, faint lateral wear facets are
readily visible (PI. 20, fig. 4) reflecting the shape of the individual maxillary teeth.

A single palatine specimen has been recovered (PI. 20, fig. 6). This is a robustly built bone bearing an enlarged
row of six or seven teeth that ran parallel to the maxillary dentition exhibiting well-defined lateral wear facets.
A small portion of the maxillary process is preserved, but medially little remains of the element and it is difficult
to determine whether there were any further palatal teeth. On the dorsal surface of the palatine, medial to the
fragmented maxillary process, are the remnants of a shallow facet (text-fig. 3, prf.f.) that probably received
a ventrally directed process from the prefrontal in the same manner as in other sphenodontids (e.g. Plano-
cephalosaurus (Fraser, 1982)).

Discussion. There is no doubt that the three elements described above are representative of the same
species. The maxilla and dentary have been found in approximately equal numbers within the
Cromhall deposits (Table 1) and the tooth form is very similar, being obtusely conical, without the
development of extensive flanges and generally not unlike that of Opisthias (text-fig. 4a). There are no
successional teeth on either maxilla or dentary and it would appear that tooth replacement was

EXPLANATION OF PLATE 20

Figs. 1-6. Sigmala sigmala gen. et sp. nov. 1, lateral view of the holotype, right maxilla, AUP no. 11083, x 5.
2 and 3, paratype, left dentary, AUP no. 1 1082. 2, lateral view, x 4; 3, medial view, x 4-5. 4 and 5, juvenile
specimen of right dentary, AUP no. 11212. 4, lateral view, x 8; 5, medial view, x 8. Note the incompletely
ankylosed posterior tooth. 6, paratype, left palatine, AUP no. 1 1084, in ventral view, x 8.

Fig. 7. Pe/ecymala robustus gen. et sp. nov. Holotype, right maxillary fragment, AUP no. 11140, in lateral
aspect, x 6.

Figs. 8 and 9. Pelecymalal dentary specimen, AUP no. 11192. 8, lateral view, x 6; 9, medial view, x 6.

PLATE 20

FRASER, Triassic sphenodontids

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PALAEONTOLOGY, VOLUME 29

table 1 . Occurrence of Sigmala sigma! a jaw-bone
elements at each site in Cromhall Quarry.

Element

Site 2

Site 3

Site 4

Site 5

mx

1

4

4

d

6

5

1

pal

2

completely suppressed in this genus, although this cannot be verified at present as the premaxilla is
unknown.

The enlarged tooth row on the palatine, posterior process on the dentary, acrodont marginal
dentition, hatchling dentition showing an alternation in size, and the probable articulation of the
prefrontal with the palatine form a suite of characters indicative of a sphenodontid. The morphology
of the dentition is particularly diagnostic with the well-defined division of the marginal series into
additional and hatchling dentitions. The additional teeth also bear rudimentary flanges, and medial
wear facets on the maxillary teeth and lateral wear facets on the mandibular dentition are
characteristic of the sphenodontid shearing bite. The wear facets reflecting the precise outlines
of opposing dentitions is a feature shared with C. hudsoni and indicates a lack of propalinal
movement. In contrast, Sphenodon and the Eilenodontinae (Rasmussen and Callison, 1981) are
perhaps rather more advanced in that propalinal movements are incorporated into the shearing
jaw action.

The relationships of Sigmala within the Sphenodontidae are not so clearly defined. The teeth do
not possess the enlarged flanges typical of Homoeosaurus and Clevosaurus and the jaws are much
deeper and more robust than Planocephalosaurus. Unlike the other Triassic sphenodontids and
Sphenodon , Sigmala does not possess an anterior successional dental series. However the tooth
morphology is not unlike that of Sphenodon and Opisthias ; all three genera exhibit an approximately
triangular lateral aspect and rudimentary flanges (text-fig. 4). However, because of the occurrence of
a propalinal jaw movement in Sphenodon , and possibly also in Opisthias , together with the reduction
of marginal tooth numbers in Sigmala , the three genera cannot be unequivocally assigned to the same
subfamily. It has been suggested elsewhere (Fraser and Walkden 1983) that Sigmala might have been
herbivorous; the deep jaw outline and anterior ‘edentulous beak’ closely resemble those of a chelonian
and the herbivorous agamid lizard, Uromastix hardwickii. In the same manner as in the Eilendontinae
the posterior mandibular teeth of Sigmala are set medial to the coronoid process (text-fig. 2a), but,
unlike that particular group of herbivorous sphenodontids the teeth of Sigmala are not transversely
broadened.

At this stage, without information regarding the skull and postcranial morphology of Sigmala ,
dental structure is the only taxonomic criterion available, and on this basis Sigmala is tentatively
considered to be most closely related to Sphenodon and Opisthias.

Genus pelecymala gen. nov.

Species Pelecymala robustus sp. nov.

A sixth sphenodontid in the Cromhall fauna is represented by just four fragments of maxilla. On
the basis of the quite distinctive additional teeth it is designated as a new genus.

Etymology. Derived from the hatchet-shaped appearance of the anterior region of the upper jaw and the strong
robust nature of the additional teeth (Gr. pelekys (neAeKvo) hatchet; L. mala jaw).

Diagnosis. Sphenodontid reptile having a maxilla estimated to be approximately 15 mm long and
bearing large transversely broadened additional teeth; maxillary hatchling teeth alternate in size; no

FRASER: TRIASSIC SPHENODONTIDS

171

a

i i

0 -5 cm

b

0-5 cm

2-0 mm

c

text-fig. 4. Reconstructions of the dentaries of a , Opisthias rarus . b . Sphenodon
punctatus, and c, Sigmala sigmala gen. et sp. nov. All in lateral view, a, after
Throckmorton et at. (1981).

successional teeth on the maxilla; additional teeth generally increase in size caudad; anterior region of
the maxilla is hatchet-shaped.

Holotype. AUP no. 11140, right maxilla.

Paratypes. AUP no. 11214, right maxillary fragment; AUP no. 11215, left maxillary fragment.

Type locality. Karstic fissures in Dinantian limestones, Cromhall Quarry, south Gloucestershire.

Horizon. Upper Triassic.

Description. Of the four maxillary fragments the most complete is AUP no. 11140, which represents the anterior
portion of a right maxilla extending from the border of the external naris and the premaxillary contact to a point
ventral to the anterior margin of the orbit (PI. 20, figs. 7 and 8; text-fig. 5). The anterior border of the bone
is concave and presumably marked the posterior boundary of the external naris in the same fashion as that
observed in Planocephalosaurus ( Fraser, 1982). A facet on the lingual surface of the bone immediately above the
tooth row (text-fig. 5b. pm.f.) is similar to the arrangement in Sigmala. and probably received an extensive
process from the premaxilla. In C. hudsoni the premaxilla possesses a forked maxillary process (text-fig. 6,
mx.pr.) and the dorsal prong extends along the posterior boundary of the external naris, thereby excluding the

172

PALAEONTOLOGY, VOLUME 29

a b

text-fig. 5. Pelecymala robustus gen. et sp. nov. Holotype, right maxilla, AUP no. 1 1 140, in a, lateral

and b , medial views.

text-fig. 6. Clevosaurus hudsoni. Left premaxilla, AUP no. 11143, in

lateral view.

maxilla from this opening. This condition did not occur in Pelecymala. However, in other respects the
articulation facets of the maxilla in Pelecymala were similar to other Triassic sphenodontids with overlapping
nasal and prefrontal contacts (text-fig. 5b, n.f., prf.f.). Thus, in medial aspect the flange of bone separating the
external naris from the orbit has an anterodorsal facet for the nasal and a posterodorsal facet for the prefrontal.
The prefrontal facet is markedly deeper than that for the nasal which suggests that the prefrontal also overlapped
the nasal at this point providing a strong bracing contact between maxilla, nasal, and prefrontal.

The maxillary dentition is typically sphenodontid with an anterior series of ten small teeth that alternate in
size. This alternation in tooth size is not as well marked as that normally seen in specimens of Clevosaurus , but
this series is still assumed to be representative of the hatchling dentition. Whilst the most anterior tooth in
AUP no. 1 1140 has broken off near its base there are no indications of the first two or three teeth being
significantly larger than the subsequent ones in the hatchling series. Thus, like Sigmala and C. hudsoni, there
appear to have been no replacement teeth on the maxilla in Pelecymala. There are only three additional teeth
preserved on AUP no. 11140, but they show quite a remarkable form, displaying a slight tendency towards
transverse broadening. This broadening of the additional teeth can be conveniently observed in AUP no. 11215
(text-fig. lb). In both AUP nos. 1 1 140 and 11215 the lingual surfaces of the additional teeth display well-defined
wear facets (text-figs. 5b and 7c, w.f.) with grooves indicative of a precise occlusion with the dentary and no
propalinal movement of the jaws.

FRASER: TRIASSIC SPHF.NODONTIDS

173

text-fig. 7 {left). Pelecymala robustus gen. et sp. nov. Paratype, left maxillary fragment, AUP
no. 11215, in a, lateral, b , dorsal, and c , medial views.

text-fig. 8 (right). Pelecymala robustus gen. et sp. nov. Paratype, right maxillary fragment, AUP

no. 11214, in a , lateral and b, medial views.

In AUP no. 11215a short section of the ventral margin of the orbit is preserved, and below this on the medial
side is a partially preserved articulation facet, which was in all probability for the jugal. Another fragment,
AUP no. 11214, representing a more posterior section of the maxilla, illustrates this facet rather more clearly
(text-fig. 86, j.f.). This specimen is from a young individual and the full complement of additional teeth was not
attained prior to death. Evidence for this is shown by the partly preserved excavation at the posterior end of the
fragment where a tooth was not completely ankylosed (text-fig. 8 a, to.alv.).

Although there is a rudimentary development of a posterolingual flange on the additional teeth of Pelecymala ,
this is not as extensive as that seen in the teeth of Clevosaurus (text-fig. 9a). Apart from the transverse broadening
the additional teeth of Pelecymala are readily distinguished from Sigmala by their relatively larger size coupled
with the progressive increase in their height caudad (text-fig. 10«, b). There is thus a unique set of dental
characteristics serving to distinguish Pelecymala from the two other fissure sphenodontids that have a similar
range in size.

There is also no question that any of the small fissure sphenodontids, such as Planocephalosaurus (Fraser.

174

PALAEONTOLOGY, VOLUME 29

text-fig. 9. Additional teeth of a, Clevosaurus hudsoni and b, Homoeosaurus maximiliani in
lateral view, b , after Cocude-Michel (1963).

add dent

2 0mm

add. dent htch dent

add dent htch dent.

text-fig. 10. Growth stages of Triassic sphenodontid maxillae, a , Pelecymala robustus gen. et sp. nov., AUP
no. 11140. b-d, Sigmala sigmala gen. et sp. nov. b, AUP no. 11360; c, AUP no. 11361; d , AUP no. 11083.
e-g, Clevosaurus hudsoni. e, AUP no. 11146; /, AUP no. 11187, reversed for comparative purposes;

g, AUP no. 11144.

1982) and Sphenodontid X, represent juvenile stages of larger genera, such as Pelecymala and Sigmala. Fairly
complete ontogenetic series are known for Planocephalosaurus, Sphenodontid X, Sigmala , and Clevosaurus , and
the juvenile stages of each form are quite different from each other (text-figs. 10 and 11) and instantly
recognizable. Indeed, for the following reasons, it is very likely that all the known material of Pelecymala
represents immature individuals. First, all the specimens have additional teeth of approximately equal height,
yet in the most complete specimen the anterior hatchling teeth are still distinct and not worn to the bone.
Secondly, as mentioned previously, AUP no. 11214 indicates that ankylosis of the full complement of additional
teeth was incomplete, at least in this specimen. Thirdly, the depth of bone between the orbit and the base of the

FRASER: TRIASSIC SPH ENO DONTI DS

175

2 Omm

add dent

succ dent

add dent. succ. dent.

a

c htcti dent,

add. dent

text-fig. 11. Growth stages of Triassic sphenodontid maxillae. a, b, Sphenodontid X.
a , AUP no. 11196; b, composite restoration of AUP nos. 11194 and 11195. c-e, Plano-
cephalosaurus robinsonae. c, AUP no. 1 1359; d. , AUP no. 1 1061, reversed for comparative

purposes; e, AUP no. 1 1093.

teeth is relatively very narrow in proportion to the height of the teeth; this suggests incomplete ossification.
Finally, and perhaps of most significance, is the underdevelopment, or complete absence, of secondary dentine in
any of the specimens. Secondary dentine is a characteristic feature of all mature individuals of the other fissure
sphenodontids (text-figs. 106, e and 1 1 ).

Dentary fragments possibly attributable to Pelecymala. Because of the paucity of recognizable jaw
bones, it has proved almost impossible to indubitably identify elements, other than the maxilla, with
the genus Pelecymala. In attempts to establish relationships between various problematic elements,
very little useful data can be produced by assessing relative abundances of particular bones when the
initial sample size is very small. However, within the Cromhall deposits, there are numerous
fragments of acrodont jaw bones bearing teeth that are transversely broadened, some of which are
likely to represent the new genus Pelecymala-. in particular there are three dentary fragments and one
palatine fragment possessing a very similar dentition.

Two of the dentary fragments are highly polished, but retain sufficient detail to merit description.
The smallest of these, AUP no. 11216, bears a single tooth which displays wear facets on both the
lingual and labial surfaces and is slightly broadened transversely (text-fig. 12). Posterior to the tooth
the bone expands dorsoventrally towards a coronoid process; the full extent of which is impossible to
restore owing to fragmentation and polishing. There would also appear to have been a posterior
process, but this too has been broken and subject to a great deal of attrition. However, from the
nature of the tooth wear facets it is reasonable to assume that the jaw occlusion was similar to that in
known sphenodontids and that an enlarged tooth row existed on the palatine. A second specimen,

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PALAEONTOLOGY, VOLUME 29

AUP no. 11217, possesses seven teeth. These teeth are transversely broadened but without a central
ridge (text-fig. 1 3); instead they gradually slope away from the lateral edge in the same manner as the
Pelecymala maxillary additional teeth. In AUP no. 11217 there are no prominent lingual wear facets
that might be indicative of palatal tooth action, but any faint facets would be obscured by the
polished nature of the specimen. The lateral surface has been sharply cut away in a vertical plane as
a result of the shearing action of the maxillary dentition. Posterior to the tooth row nothing further of
the element has been preserved.

b

text-fig. 12 (left). Pelecymala! dentary fragment, AUP no. 11216, in «, lateral and b , dorsal views.
text-fig. 13 (right). Pelecymala ? dentary fragment, AUP no. 11217, in dorsal aspect.

The most complete of the three dentary specimens, AUP no. 11192, represents the anterior section
of a right element, extending from the symphysis to a point assessed to be mid way along the tooth
ramus (PI. 20, figs. 8 and 9; text-fig. 14). Like Clevosaurus and Sphenodon (Robinson, 1976), the teeth
can be categorized into three distinct series: successional, remanent hatchling, and additional. The
first two teeth are transversely broadened, but again without a transverse ridge. The bases of these
teeth are set deeper than the succeeding teeth and are therefore considered to represent the only tooth
positions at which replacement has occurred: the bone having been eroded and reabsorbed to
accommodate the larger replacement teeth. Following the two successional teeth are six or seven
smaller teeth which are the remnants of the hatchling dentition. They exhibit alternation in size, but
like the Pelecymala type specimen, this is not accentuated to the extent of Clevosaurus. Posterior to
the remanent hatchling series are three or four larger teeth which show a trend to increase in size
posteriorly. These represent part of the additional series and they are transversely broadened in an
identical fashion to the two successional teeth. Thus the highest point of each tooth is at the lateral
edge where the maxillary teeth made their shear contact. The additional teeth also have a small
anterolateral flange and possibly a rudimentary posterolateral one. These are best observed in lateral
view (PI. 20, fig. 9). The overall shape of AUP no. 1 1 192 is not dissimilar to the dentary of C. hudsoni
and both have a prominent jaw symphysis. But whilst apparently of a similar length, AUP no. 11192
is perhaps somewhat deeper than the typical C. hudsoni dentary.

FRASER: TR1ASSIC SPHENODONTI DS

177

text-fig. 14. Pelecymalal dentary specimen, AUP no. 1 1 192, in dorsal aspect.

b

text-fig. 15. Pelecymala! palatine specimen, AUP no. 11218, in a, ventral and

b, lateral views.

These three dentary specimens apparently represent a single species, and, although generally not
well preserved, they represent a sphenodontid of similar proportions to, and a dentition comparable
with, Pelecymala.

A solitary palatine fragment has been identified which bears an enlarged row of transversely
broadened teeth (text-fig. 15). Unfortunately the specimen is rather fragmentary and worn, but it
bears the remnants of five teeth forming the posterior end of a single tooth row. Posterolaterally the
element has a grooved facet for the ectopterygoid (text-fig. 156, ect.f.) which conforms to the typical
sphenodontid pattern. Much of the medial and anterior portions of the element are missing,
including the maxillary and pterygoid facets. The teeth display lateral wear facets, but their full extent
has been obscured by degradational polishing, so that although there is no indication of grooved
facets that would infer a precise occlusion with the dentary, such an occlusion with no propalinal
movement cannot be discounted.

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P ROLACERT I FORMES

ARCHOSAURIA

PALAEONTOLOGY, VOLUME 29

RHYNCHOSAURIA

YOUNGINIFORMES

SQUAMATA

text-fig. 16. The classification of the diapsids as proposed by Benton (19846).

The overall poor preservation of the palatine and the lack of any other similar elements restricts the
discussion of its affinities. The only positive statements that can be made are that it is a sphenodontid
palatine with teeth broader than long, but with no transverse ridge, and in this respect it is not
dissimilar to Pelecymala. It is also within the size range expected for the palatine of that genus.

THE TAXONOMIC POSITION OF THE FAMILY SPHENODONTIDAE

Romer (1966) placed all diapsid reptiles into two subclasses: the Archosauria and the Lepidosauria.
He believed that these two subclasses diverged from separate ancestors in the Upper Carboniferous.
Within the Lepidosauria Romer included the order Rhynchocephalia to incorporate the rhynchosaurs
and sphenodontids. In Romer’s classification the subclass Diapsida, established by Osborn (1903),
was regarded as obsolete.

More recently Romer’s traditional classification has been questioned and it is now more widely
believed that the Archosauria and Lepidosauria had a common ancestry, and that all diapsid reptiles
can be derived from a form similar to Petrolacosaurus — a primitive Carboniferous eosuchian (Reisz
1977, 1981). Evans (1980) subsequently outlined a new classification incorporating the concept of the
diapsids as a monophyletic group and reinstated the subclass Diapsida.

In the most recent work on the Diapsida, cladistic analyses have produced classifications (Benton
19846; Evans 1984; Gauthier, in press) which suggest that two main lineages diverged during Permian
times: namely the Archosauromorpha and the Lepidosauromorpha (text-fig. 16). However, further
discussion of this concept is beyond the scope of the present paper, suffice to say that the
sphenodontids are incorporated into the Lepidosauromorpha, probably as the sister group of the
Squamata.

Recent work has also questioned the affinities of the rhynchosaurs and sphenodontids. Carroll
(1976) showed that the ankle joint of Noteosuehus , a primitive rhynchosaur, is in fact similar to that of
the thecodont, Proterosuchus, and that supposed shared characters of rhynchosaurs and spheno-
dontids are either primitive features of diapsids generally or have been wrongly interpreted. To take
an example of the latter, the supposed acrodont teeth of rhynchosaurs have now been shown to
possess deep roots (Chatterjee 1974; Benton 1983). Following Romer (1956), I initially (Fraser, 1982)
recognized the order Rhynchocephalia to consist of the rhynchosaurs and sphenodontids, but, since

FRASER: TRIASSIC SPHENODONTI DS

179

it is apparent that they share only a very few primitive characters, they should now be separated. The
complex concave-convex ankle joint is a feature shared by archosaurs, prolacertiformes, and
rhynchosaurs (Thulborn 1980; Brinkman 1981), but not sphenodontids. This, together with other
synapomorphies (for list see Benton (19846)), shows that the rhynchosaurs belong to the
Archosauromorpha assemblage.

The name Rhynchocephalia was erected for the genus Sphenodon by Gunther (1867) and the
rhynchosaurs were added later. Now that it is deemed necessary to separate the two groups, the order
Rhynchocephalia should strictly be applied to Sphenodon and its allies. However, as a result of
the past association of the rhynchosaurs with the Rhynchocephalia, Estes (1983) suggested that the
sphenodontids should be placed in a new order, the Sphenodontida. Carroll (in press) adds the
pleurosaurs to this order.

INTER-RELATIONSHIPS WITHIN THE SPH ENO DONTI D AE

S. punctatus Gray 1832 is the sole surviving member of a family that flourished in the Triassic and
Jurassic. Previously the lack of abundant fossil representatives of the family has led to our knowledge
of the Sphenodontidae being rather restricted. Just as the affinities of the family have been
questioned, the history of the taxonomy at subfamilial level has been varied. Some classifications,
such as that of von Huene (1956), placed particular emphasis on temporal relationships. Thus von
Huene recognized three subfamilies of the Sphenodontidae; the Brachyrhinodontinae (Triassic), the
Monjurosuchinae (Jurassic), and the Sphenodontinae (Jurassic to Recent). Other recent classifica-
tions (Table 2) have been based primarily on structural morphology but each has used slightly
different criteria, and are incomplete. To update the classification of the Sphenodontidae, so that all
recently described forms are included, I have adopted an eclectic approach and used a combination of
the most recent classifications. Because tooth morphology is the only character that can be
satisfactorily examined in many of the known sphenodontids, I have relied mostly on Rasmussen and
Callison's (1981) (Table 2) classification system.

One of the most primitive sphenodontids is probably Polysphenodon from the Trias of Hanover
which possesses numerous rows of teeth on the palate, including an ectopterygoid dentition. Jaeckel
(1911) restored the palate of Polysphenodon with no subtemporal fossa between the palatine and the
ectopterygoid, but this is apparently incorrect and the typical subtemporal fossa does exist (R. L.
Carroll, pers. comm.). Bearing this in mind the palate of Planocephalosaurus is not dissimilar to that
of Polysphenodon , although the ectopterygoid is not dentigerous in the former genus (Fraser 1982).
Sphenodontid X also possesses the vast majority of sphenodontid characteristics, yet it too has
a number of palatal teeth and in addition part of the marginal dentition has a pleurodont implanta-
tion (Whiteside 1983). Even more primitive in this respect is the Jurassic genus Gephyrosawus ( Evans
1980, 1981) which possesses a totally pleurodont marginal dentition. Evans (1984) believed
Gephyrosawus to be the sister group of the squamates and that the sphenodontids formed the sister
group of Gephyrosawus and the squamates together. She considered (Evans 1980, 1981, 1984) that
the similarities between Gephyrosawus and the sphenodontids resulted from homoplasy. However,
some characters which she cited as evidence for a Gephyrosawus- squamate sister grouping separate
from the sphenodontids are to be found in some sphenodontids. These include the fusion of the
frontals and parietals and a concavity in the astragalocalcaneum for the reception of a process on the
fourth distal tarsal. Whiteside (1983) has offered strong evidence to suggest that Gephyrosawus is
a sphenodontid and Fraser and Walkden (1984) also believed this to be the case. Elachistosuchus ,
originally described by Janensch (1949) as a pseudosuchian, was concluded by Walker (1966) to be
a primitive sphenodontid with numerous marginal teeth.

It is therefore proposed that Planocephalosaurus , Sphenodontid X, Gephyrosawus , and Elachisto-
suchus are placed together with Polysphenodon in the subfamily Polysphenodontinae. All are
characterized by numerous palatal teeth and a relatively large number of approximately conical
marginal teeth which are mostly acrodont. The pleurodont dentition that occurs in some forms
probably recalls the occurrence of an intermediate pleurodont stage in the evolution of acrodonty

180

PALAEONTOLOGY, VOLUME 29
table 2. Outline Classification of sphenodontids according to various authors.

Order Rhynchocephalia
Suborder Sphenodontia

Family Sphenodontidae — Sphenodon, Homoeosaurus, Opisthias
(amphicoelous vertebrae, acrodont dentition)

Family Sapheosauridae— Sapheosaurus, Piocormus
(procoelous vertebrae?, edentulous, enlarged supratemporal?)

Family Monjurosuchidae — Monjurosuchus
(3 sacral vertebrae, 3 mandibular tooth rows)

(Hoffstetter 1955)

Family Polysphenodontidae — Poly sphenodon
Family Sphenodontidae

Subfamily Brachyrhinodontinae — Brachyrhinodon

Subfamily Sphenodontinae— Sphenodon, Elachistosuchus , Opisthias , Clevosaurus
Subfamily Flomoeosaurinae— Homoeosaurus, Kallimodon, Leptosaurusl ( = Kallimodori)

?Family Palacrodontidae- Pu/ac/Won

(Kuhn 1969)

Family Sphenodontidae

1. Triassic genera, e.g. Polysphenodon

2. Broad parietal table, e.g. Homoeosaurus

3. Narrow parietal table, e.g. Kallimodon , Sapheosaurus , Sphenodon ?

(Cocude-Michel 1963)

Family Sphenodontidae

Subfamily Brachyrhinodontinae, e.g. Brachyrhinodon
(conical teeth, numerous palatal teeth)

Subfamily Sphenodontinae, e.g. Sphenodon , Opisthias , IC/evosaurusl
(teeth circular or square in frontal section)

Subfamily Homoeosaurinae, e.g. Homoeosaurus, Kallimodon
(teeth elongated anteroposteriorly)

Subfamily Eilenodontinae, e.g. Eilenodon, Toxolophosaurus
(teeth elongated mediolaterally)

(Rasmussen and Callison 1981)

from a primitive protothecodont condition. As a result of grouping all the primitive forms together
the possibility that the Polysphenodontinae is a paraphyletic group still remains, but with the data
available it cannot be resolved any further.

Fragmentary material of an unnamed sphenodontid from the Kirkwood Formation, South Africa
(Rich el al. 1983), shows some similarities to the Polysphenodontinae. In addition the conical dentary
teeth of Theretairus , described by Simpson (1926) from the upper Jurassic of Wyoming, also show
some affinities to that subfamily. However, there is insufficient material to make a positive assertion
with regard to their relationships.

The occurrence of Brachyrhinodon fossils as rather poorly preserved casts in the Elgin sandstone
makes the material difficult to work with and the palate is undescribed. Consequently the affinities of
Brachyrhinodon are difficult to assess. Following Kuhn ( 1969) it is here tentatively retained within the
subfamily Brachyrhinodontinae, but with further study may be shown to be a member of the
Polysphenodontinae. Walker (1966) thought Brachyrhinodon and Polysphenodon might be closely
related, even possibly congeneric, although he offered little evidence to support this view.

With respect to the problematical Triassic genus, Palacrodon, it is very difficult to classify on the
basis of a single fragment of lower jaw. Malan (1963) stated that it could be ‘an aberrant pro-
colophonid or lizard just as easily as an aberrant rhynchocephalian’. Whilst this is perhaps true, there
are certain features of the teeth which are very similar to teeth recovered from the Cromhall fissure

FRASER: TRIASSIC SPH ENODONTIDS

181

deposits, as well as from deposits at Highcroft Quarry, Gurney Slade, Somerset (text-fig. 17), which
I consider to be representative of the genus Clevosaurus. Thus, if Palacrodon were to be accepted as
a sphenodontid it would seem reasonable to assign it to the same subfamily as Clevosaurus.

Kuhn (1969) included Clevosaurus in the subfamily Sphenodontinae along with Sphenodon and
Opisthias', yet the teeth of the latter two are quite distinct from Clevosaurus, lacking the prominent
flanges on the maxillary and mandibular additional teeth. Of the Cromhall sphenodontids Sigmala
approaches most closely the SphenodonjOpisthias tooth form, bearing approximately triangular
teeth with anterior and posterior keels. At this point the little-known sphenodontids from the Upper
Triassic Forest Sandstone of Rhodesia, briefly described by Gow and Raath (1977), will be
mentioned. Whilst details of their tooth structure are unavailable, from what is known they are not
unlike Sigmala and possess a short jaw ramus and no successional teeth. They are therefore
tentatively placed in the Sphenodontinae.

TO mm

text-fig. 17. a , isolated Clevosaurus tooth, AUP no. 1 1354, from Cromhall Quarry, b , acrodont
tooth, BMNH R.6109, from Highcroft Quarry, c, dentary of Palacrodon (after Broom 1906).

The teeth of Clevosaurus are most like those of Homoeosaurus (text-fig. 9) and the subfamily
Homoeosaurinae is consequently taken to comprise Clevosaurus , Kallimodon , Sapheosaurus ,
Homoeosaurus itself, and possibly Palacrodon. As Cocude-Michel (1963) pointed out, there may be
evidence to suggest a further subdivision on the basis of the width of the parietal table, thereby
separating Kallimodon and Sapheosaurus (text-fig. 186, c) on the one hand from Homoeosaurus { text-
fig. 18a) and Clevosaurus on the other. Although Sapheosaurus is edentulus it has been placed within
the Homoeosaurinae on the basis of its cranial similarity to Kallimodon.

The last of the five subfamilies is the Eilenodontinae which includes the highly specialized
Toxolophosaurus, EUenodon , and possibly also Pelecymala; the latter showing a tendency to
transverse broadening of the additional teeth.

Outline of the proposed classification (text-fig. 19)

Family sphenodontidae

Diapsida with enlarged palatine tooth row running parallel or almost parallel to the maxillary
dentition; prefrontal with ventral process articulating on the dorsal surface of the palatine; lachrymal
characteristically absent; posterior process on the dentary; dentition usually acrodont, and hatchling
dentition characteristically alternates in size; vertebrae notochordally amphicoelous; pelvic girdle
with a large thyroid fenestra; posterior tubercle on the ischium; ent— and ectepicondylar foramina
retained on the humerus; fused astragalocalcaneum.

(i) Subfamily polysphenodontinae. Upper Triassic-Lower Jurassic. Sphenodontids possessing
multiple tooth rows on the palate; marginal teeth approximately conical and usually acrodont
although may show various degrees of pleurodonty.

(ii) Subfamily brachyrhinodontinae? Upper Triassic. The sole genus is Brachyrhinodon which
bears a characteristically short snout. However other features include the numerous small teeth and
broad parietal table which indicate some relationship to the Polysphenodontinae.

182

PALAEONTOLOGY, VOLUME 29

text-fig. 18. Reconstructions in dorsal view of the skulls of a, Homoeosaurus maximiliani, b, Kallimodon
pulchellus, c, Sapheosaurus thiollierei, and <7, Paleopleurosaurus posidonieni. a-c, after Cocude-Michel

(1963); d , after Carroll (in press).

(iii) Subfamily sphenodontinae. Upper Triassic?-Recent. Sphenodontids bearing a fully
acrodont marginal dentition; usually a single tooth row on the palatine; marginal dentition
approximately triangular in side view with small posterior and anterior keels.

(iv) Subfamily homoeosaurinae. Upper Triassic-Upper Jurassic. Sphenodontids which charac-
teristically have flanged additional marginal dentition so that the teeth are much longer than they
are wide.

(v) Subfamily eilenodontinae. Upper Jurassic-Lower Cretaceous. Sphenodontids in which the
marginal teeth are transversely broadened; wear facets on mandibular teeth characteristically
approach the horizontal on the medial side.

CONCLUSIONS

Within the Sphenodontidae there is a broad evolutionary trend towards a reduction in tooth numbers
coupled with a suppression of tooth replacement, not only in the marginal but also in the palatal
dentitions. These changes are associated with the development of a powerful shearing bite.

The ancestral forms are likely to have been similar to Gephyrosaurus and Sphenodontid X,
possessing numerous relatively small teeth with no flanges. The majority, if not all, the marginal teeth
were probably pleurodont with some replacement occurring at each tooth position within the life of
an individual. Numerous small palatal teeth would be expected in the ancestral form scattered across
the vomers, palatines, pterygoids, and possibly the ectopterygoids. The advanced characteristics seen
to occur in Gephyrosaurus and Sphenodontid X, such as the fused skull roofing elements, would not

FRASER: TRIASSIC SPHENODONTIDS 183

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text-fig. 19. The author’s classification of the sphenodontids.
A, diapsids with an enlarged palatal tooth row running parallel
or almost parallel to the maxillary dentition; posterior process
on the dentary; posterior tubercle on the ischium. B, much
reduced snout region. C, fully acrodont marginal dentition;
palatal dentition confined almost entirely to a single row on the
palatine. D, additional teeth elongated anteroposteriorly.

E, additional teeth elongated mediolaterally.

be expected in the stem sphenodontids, but would have been acquired later, possibly as a specialized
offshoot.

The next evolutionary stage might have been similar to Planocephalosaurus, but again in all
probability without the fusion of the frontals and parietals seen in this genus. In Planocephalosaurus
all of the marginal dentition is acrodont, but in the adult all the premaxillary, the first four maxillary
and the first five or six mandibular teeth are successional, having undergone a single tooth
replacement soon after hatching. Sphenodon punctatus exhibits a reduction to two or three
successional teeth on the maxilla and dentary, whilst in Sigmala sigmala and C. hudsoni the ultimate
stage is reached with the absence of any successional teeth on either the maxillary or dentary.
However, at present no sphenodontids are known in which tooth replacement is seen to have been
suppressed completely. C. hudsoni bears at least one successional tooth on the premaxilla and
Sigmala might yet be found to possess premaxillary successional teeth. Likewise the Jurassic genera
Homoeosaurus and Kallimodon both possess successional teeth on the premaxilla: the former with
two large teeth and the latter with apparently just one very large tooth. Cocude-Michel (1963)
considered Leptosaurus Fitzinger 1837 to be a juvenile individual of Kallimodon. Leptosaurus displays
two premaxillary teeth which could have been replaced by a single one in the adult. Sapheosaurus is
a special case in being completely devoid of teeth and thus cannot be considered in the context of
tooth replacement.

The number of palatal teeth have been gradually reduced in the evolutionary sequence until there
is only the single enlarged tooth row remaining in Sigmala, Homoeosaurus , Kallimodon , and
Sphenodon.

184

PALAEONTOLOGY, VOLUME 29

The development of a shearing jaw action can also be traced within the Sphenodontidae. The
Polysphenodontinae generally exhibit little, if any, evidence of a shearing bite. In Gephyrosaurus and
Sphenodontid X the jaws are slender and the small teeth acutely conical. Whilst there are wear facets
on some of the posterior marginal teeth, their distribution is quite random. Evans (1980) concluded
that such wear facets were probably produced by tooth to food wear rather than tooth to tooth
occlusion. Although Plcinocephalosaurus does exhibit rather more organized wear facets (Fraser and
Walkden 1983) — particularly noticeable on the dentary— these are not prominent and in some
instances they are very poorly defined. Clevosaurus and Sigmala have advanced a stage further and
display prominent wear facets on the marginal dentition which have been derived from tooth to tooth
occlusion. The well-defined scoring pattern is indicative of a precise occlusion between upper and
lower jaws. The jaws have become deeper and the palatal tooth rows assumed greater importance
since they too exhibit extensive lateral wear facets. In the Eilenodontinae the development of a
shearing jaw action reached its peak. The jaws were deep, relatively short, and with stout, closely
packed marginal teeth. The mandibular dentition occluded between the maxillary and palatal
tooth rows producing extensive wear facets. In addition propalinal jaw movements probably
increased the efficiency of shredding and eliminated the distinctive grooved facets characterized
by Clevosaurus.

In the Triassic genera in which the parietals are known, they form a broad flat table separating the
supratemporal fenestrae, although in Clevosaurus this parietal table is somewhat narrower. The
Jurassic genus Homoeosaurus also possesses a broad parietal table, but in Kallimodon , Sapheosaurus ,
and Sphenodon the parietals are much narrower and are raised to form a parietal ridge. This feature
has resulted in the enlargement of the supratemporal fenestrae which, together with the ventral
extension of the parietals, may have facilitated a greater development of the external jaw adductor
musculature. Unfortunately the parietal region is not known in all sphenodontids and it is therefore
difficult to assess whether the narrow parietal ridge is associated with the development of a powerful
shearing bite.

Pleurosaurs such as Paleopleurosaurus (text-fig. 18c/) also exhibit a narrow parietal table which,
considering other sphenodontid affinities, may be indicative of origins from the same stock as
Kallimodon , Sapheosaurus , and Sphenodon. If the structure of the parietal table is taken as a diagnostic
derived character, then pleurosaurs, Sphenodon , Kallimodon , Sapheosaurus , and Piocormus may
represent an advanced taxon separate from the Triassic sphenodontids and Homoeosaurus. On the
other hand, Polysphenodon and Br achy rhino don, which are primitive in most respects, share with
Sphenodon the lateral bowing of the lower temporal arcade (Carroll, in press). This is almost certainly
a derived character relative to other sphenodontids (D. I. Whiteside, pers. comm.). The situation is
complicated further by the occurrence of a supratemporal in Clevosaurus (Robinson 1973). This
element has not been reported in any other sphenodontid, but it is present in Youginiformes and
some squamates.

There is thus a mosaic of primitive and derived characters present in the various members of the
Sphenodontidae which cannot be readily reconciled together. It is not possible at present to justify
the separation of the Triassic sphenodontids and Homoeosaurus from Sphenodon , Kallimodon , and
related forms and much more information is needed before the implications of parietal variation can
be discussed relative to sphenodontid classification. However, it is hoped that future work on
Clevosaurus , Brachyrhinodon , and Polysphenodon may go a long way to clarifying the situation.

Acknowledgements. I thank Drs A. R. I. Cruickshank and M. J. Benton for their constructive criticism of various
drafts of the manuscript and their many helpful suggestions. Dr L. B. Halstead has been a continual source of
encouragement for my research into the Triassic fissure deposits and Dr G. M. Walkden has also provided much
invaluable help, particularly in the field. I have benefited greatly from discussions with Drs R. L. Carroll, S. E.
Evans, and D. I. Whiteside. I am grateful to the management of Amey Roadstone Corporation Ltd. for
permission to work in Cromhall Quarry, and to the British Museum for access to specimens in their care. I thank
the NERC for partially supporting the work financially and Professor P. E. Brown provided facilities at
Aberdeen University.

FRASER: TRIASSIC SPH ENODONTI DS

185

ABBREVIATIONS USED IN TEXT-FIGURES

add.

additional

m.

median

alv.

alveolus

ma.

matrix

ant.

anterior

mc.g.

meckelian groove

art.

articular

mx.

maxilla

br.

broken

n.

nasal

c.

coronoid

pal.

palatine

d.

dentary

pm.

premaxilla

dent.

dentition

post.

posterior

ect.

ectopterygoid

pr.

process

ex.na.

external naris

prf.

prefrontal

f.

facet

s.d.

secondary dentine

fo.

foramen

succ.

successional

frg-

fragmented

symp.

symphysis

htch.

hatchling

to.

tooth

j-

jugal

w.f.

wear facet

1.

lappet

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broom, r. 1906. On a new South African Triassic rhynchocephalian. Trans. R. Soc. S. Afr. 16, 379-380.
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cocude-michel, m. 1963. Les Rhynchocephales et les Sauriends des calcaires Lithographique (Jurassique
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Stuttgart.

evans, s. e. 1980. The skull of a neweosuchian reptile from the Lower Jurassic of South Wales. Zool. J. Linn. Soc.
70, 203-264.

1981. The postcranial skeleton of the Lower Jurassic eosuchian. Gephyrosaurus bridensis. Ibid. 73, 81-116.
1984. The classification of the Lepidosauria. Ibid. 82, 87-100.
eraser, N. c. 1982. A new rhynchocephalian from the British Upper Trias. Palaeontology , 25, 709-725.

— and walkden, g. m. 1983. The ecology of a late Triassic reptile assemblage from Gloucestershire, England.
Palaeogeog., Palaeoclimat., Palaeoecol. 42, 341-365.

— 1984. The postcranial skeleton of Planocephalosaurus robinsonae. Palaeontology , 27, 575-595.
Gauthier, j. a. (in press). Phylogenetic relationships of the Lepidosauromorpha and the origin of Lizards.
Am. Zool.

gow, c. E. and raath, m. a. 1977. Fossil vertebrate studies in Rhodesia: sphenodontid remains from the Upper
Trias of Rhodesia. Paleont. afr. 20, 121-122.

Gunther, a. 1867. Contribution to the anatomy of Hatteria ( Rlivnchocephalus , Owen). Phil. Trans. Roy. Soc.
Lond. 167, 595-629.

huene, F. von. 1956. Paldontologie und Phylogenie der niederen Tetrapoden. Gustav Fischer Verlag, Jena.
hoffstetter, r. 1955. Rhynchocephales. In piveteau, j. ( ed . ) . Traite de Paleontologie, 556-576. Masson et Cie,
Paris.

jaekel, o. 1911. Die Wirbeltiere. Berlin.

janensch, w. 1949. Ein neues reptil aus dem Keuper von Halberstadt. Neues Jb. Miner. Geol. Palaont. Mh ,
Abt B, 225-242.

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kermack, d. 1984. New prosauropod material from South Wales. Zool. J. Linn. Soc. 82, 1011 17.
kuhn, o. 1969. Encyclopedia of Palaeoherpetology. 9. Proganosauria-Protorosauria. Gustav Fischer Verlag,
Stuttgart.

malan, M. E. 1963. The dentition of the South African Rhynchocephalia and their bearing on the origin of
rhynchosaurs. S. Afr. J. Sci. 59, 214-219.

marshall, j. E. a. and Whiteside, D. I. 1980. Marine influences in the Triassic ‘uplands’. Nature, Lond. 287,
627-628.

osborn, h. f. 1903. The reptilian subclasses Diapsida and Synapsida and the early history of the Diaptosauria.
Mem. Am. Mus. Nat. Hist. 1, 449-507.

rasmussen, t. E. and callison, g. 1 98 1 . A new herbivorous sphenodontid (Rhynchocephalia: Reptilia) from the
Jurassic of Colorado. J. Paleont. 55, 1 109-1 1 16.

reisz, R. R. 1977. Petrolacosaurus , the oldest known diapsid reptile. Science, N.Y. 196, 1091 1093.

— 1981. A diapsid reptile from the Pennsylvanian of Kansas. Spec. Publ. Mus. Nat. Hist. Univ. Kans. 7, 1-74.
rich, t. h. v., molnar, r. e. and rich, p. v. 1983. Fossil vertebrates from the Late Jurassic or early Cretaceous
Kirkwood Formation, Algoa Basin, Southern Africa. Trans, geol. Soc. S. Afr. 86, 281-291.
robinson, p. L. 1973. A problematic reptile from the British Upper Trias. J. geol. Soc. Lond. 129, 457-479.

1976. How Sphenodon and Uromastix grow their teeth and use them. In bellairs, a. d’a. and cox, c. b.
(eds.). Morphology and Biology of Reptiles, 43-64. Academic Press, London.
romer, a. s. 1956. The Osteology of the Reptiles. University of Chicago Press, Chicago.

1966. Vertebrate Paleontology. University of Chicago Press, Chicago.
simpson, G. G. 1926. American terrestrial Rhynchocephalia. Am. J. Sci. 12, 12-16.

Throckmorton, g. s., hopson, j. a. and parks, p. 1981. A re-description of Toxolophosaurus cloudi Olson,
a lower Cretaceous herbivorous sphenodontid reptile. J. Paleont. 55, 586-597.
thulborn, r. a. 1980. The ankle joint of archosaurs. Alcheringa, 4, 241-261.

walker, A. D. 1966. Elachistosuchus, a Triassic rhynchocephalian from Germany. Nature, Lond. 211, 583-585.
Whiteside, D. I. 1983. A fissure fauna from Avon. Ph.D. thesis (unpublished). Bristol University. 216 pp.

-and robinson, d. 1983. A glauconitic clay-mineral from a speleological deposit of late Triassic age.
Palaeogeog., Palaeoclimat., Palaeoecol. 41, 81-85.

N. C. FRASER

Department of Geology and Mineralogy
Marischal College
Aberdeen AB9 IAS

Present address:

University Museum of Zoology
Downing Street
Cambridge

Typescript received 22 March 1985
Revised typescript received 16 May 1985

A BIOMETRIC RE-EVALUATION OF THE
SILURIAN BRACHIOPOD LINEAGE
STRICKLANDIA LENS/S. LAEVIS

by B. GUDVEIG BAARLI

Abstract. Quantitative data from Norway, Estonia, and the Llandovery area in Wales are used to re-evaluate
the existence of the Stricklandia lens I S. laevis part of the Stricklandia\Costistricklandia evolving lineage. Two of
the directed trends originally used to discriminate subspecies in material of the type Llandovery area fall within
the same range of variation at roughly contemporaneous horizons in the Lower Silurian of Norway, Wales, and
Estonia. These are reduction of the outer plates relative to the inner plates, and reorientation of the inner plates.
A third trend in the Llandovery material, increasing size of cardinalia, does not occur in the Norwegian material
and is regarded as environmentally determined. The stricklandiids show large phenotypic variation within
sample populations and correlation must be based on a minimum of ten specimens. The four lowermost
subspecies of Williams (1951) occur abundantly in a nearly continuous section in Norway, providing material
for refined biocorrelation through an index combining the two evolutionarily valid trends.

Gould and Eldredge (1977) listed the essential criteria for an adequate test of evolutionary
models: good geographic coverage, long sequences of closely spaced samples, unambiguous
definition of taxa, and adequate biometrical testing on a sufficiently large database. Few if any studies
on macrofossils were found by Gould and Eldredge to meet all these requirements. Arnold ( 1 966) and
Johnson and Colville (1981 ) further stressed the importance of tests for simultaneous occurrence in
different geographical localities in order to exclude the presence of non-evolving geographical dines.
In addition, Sadler (1981) and Schindel (1982) showed that sedimentary sequences with frequent
periods of non-deposition and erosion are more the rule than the exception, thus making the validity
of most micro-evolutionary studies questionable. Even if the micro-evolutionary patterns involved
cannot be fully revealed, however, evidence for the widespread existence of a lineage is valuable as a
tool for biostratigraphic correlation. The existence of a lineage must be tested following the criteria
mentioned above, although a lower degree of resolution may be sufficient for practical applications in
chronostratigraphy. The purpose of this contribution is to test the validity of parts of the often cited
Stricklandia! Costistricklandia lineage in the Lower Silurian of Norway, Estonia, and Wales.

PREVIOUS WORK

Kiaer ( 1 908, pp. 499-50 1 ) was the first to suggest a stricklandiid lineage based on material in Norway.
This was later expanded and confirmed in the classic work of Williams ( 1951 ) on the Llandovery area
of Wales. Rubel (1977) found and described the same lineage from Estonia while Johnson (1979)
found parts of the lineage in Iowa. Representatives of the Stricklandia-Costistricklandia lineage have
a widespread distribution in the Lower Silurian occurring in North America (Berry and Boucot
1970), the British Isles (Ziegler et al. 1974), eastern Europe, especially the Baltic region (Kaljo 1979),
and Scandinavia (St. Joseph 1938; Bassett and Cocks 1974). Although the taxa are widespread, well
described, and the lineage is widely employed, a detailed biometric study has never been attempted.

All earlier studies on the Stricklandia-Costistricklandia lineage have shown that the features of
evolutionary significance occur in the internal structures of the cardinalia while external features
show great plasticity. Shell shape or length of the interarea are therefore of little systematic value
(Kiaer 1908; St. Joseph 1935; Williams 1951; Johnson 1979).

IPalaeontology, Vol. 29, Part 1, 1986, pp. 187-205, pi. 21.|

188

PALAEONTOLOGY, VOLUME 29

The lineage includes five stricklandiid taxa based on features in the cardinalia, from the oldest S.
lens prima Williams, 1951 through S. I. lens (J. de C. Sowerby, 1839), S. I. intermedia Williams, 1951,
and S. I. progressa Williams, 1951 to the youngest S. I. ultima Williams, 1951. The latter was
considered by Cocks (1978) to belong to a separate species, S. laevis (J. de C. Sowerby, 1839), with a
transitional position to C. lirata (J. de C. Sowerby, 1839).

The taxa of the lineage treated by Williams (1951, p. 88) represent according to him 'simply four
stages of development that the species passes through during its existence’ and 'the choice of these
particular stages has been dictated by convenience and not by more objective considerations’.

OCCURRENCE OF ST R ICKL AND1 1 DS

All representatives of the Stricklandia-Costistricklandia lineage are present in the Llandovery succession of the
Oslo Region in Norway. The Asker District, lying south-west of Oslo (text-fig. 1a, b), is the main area for this
study because all taxa are well represented there. They also occur in the Oslo, Ringerike, Holmestrand, and Skien
districts (text-fig. 1a).

The Llandovery of the central Oslo Region consists of the oldest Solvik, middle Rytteraker, and youngest Vik
formations. In the Asker District stricklandiids occur very rarely from 1 1 m to 95 m above the base of the Solvik
Formation but from this level to the top of the formation they are very abundant. At Sandvika, 5 km north of the
main investigated area (text-fig. 1b), abundant stricklandiids occur where the Solvik Formation is exposed,
except in the basal beds. They occur both in mudstone and in limestone intercalations. In limestone they are
often articulated and in their growth position. In mudstone they are mostly disarticulated but there are few signs
of distant transport.

Stricklandiids are only common in the overlying Rytteraker Formation in a 1 -5 m thick shale interbed in the
middle of the otherwise calcareous formation in the Skien District. The specimens occur in a transported and
mixed benthic assemblage. The same kind of occurrence within shaly interbeds can be seen at the base of the Vik
Formation at Sandvika and at Malmoya in the Oslo District.

The Vik Formation of Asker, Skien, and Ringerike yields Costistricklandia which is also found at the top of
the overlying Bruflat Formation at Ringerike. The specimens occur in nests in situ in calcareous interbeds.

BIOSTRATIGRAPHIC FRAMEWORK OF THE NORWEGIAN SECTIONS

Table 1 shows the main fossil taxa used for biocorrelation in the Llandovery of the Asker area, the data taken
mainly from Worsley et al. (1983). These data suggest that the base of the Solvik Formation in the Asker District
lies close to the base of the Silurian. This is supported by a basal fauna with a strong Ordovician aspect mixed
with a few typical Silurian species (Baarli and Harper, in press). Beds occurring 170 m above the formational
base are certainly younger than the uppermost atavus biozone, and probably as young as the cyphus biozone.
A level 211m above the base could still be within the cyphus biozone, but is probably of gregarius biozone age
since conodonts and brachiopods in the topmost 20 m of the 245 m thick formation are indicative of, or close to,
the sedgwickii graptolite biozone. The occurrence of stricklandiids at the base of the Vik Formation must lie
between m\d-sedgwickii to basal turriculatus graptolite biozones.

SEDIMENTARY SETTING OF THE SOLVIK FORMATION
IN THE ASKER DISTRICT

The lithostratigraphy and sedimentology of the Solvik Formation are described in detail by Baarli (1985). The
lower 170 m are fairly uniform and consist of medium to thickly bedded mudstone with very thin to thin
calcareous siltstone to silty limestone interbeds (the Myren Member) and more pure limestone interbeds (the
Spirodden Member). The upper 75 m thick Leangen Member starts with a 20 m thick, very shaly sequence which
grades into medium to thickly bedded mudshale with thin to medium thick storm-derived silt to fine sandstone
intercalations (all references to thickness of beds follow the scheme of Ingram 1954). There are no clear
indications of major pauses in sedimentation or erosional gaps, but the most likely horizon is the transition
between the lower 170 m and the upper 75 m. Here the change in lithology is very abrupt.

Sedimentological studies and palaeoecological analysis suggest a storm-dominated platform with two main
shallowing up sequences separated by a deepening; another less pronounced deepening occurs at the top of the
formation (Baarli 1985). The topmost shallowing-up sequence was deposited in a shallower and more proximal

BAARLI: SILURIAN BRACHIOPOD LINEAGE

189

table 1. The biostratigraphically important taxa in the Llandovery of the Oslo and Asker districts. Where
occurrences are referred to the stages of Cocks et al. (1970) in the literature these are correlated to graptolite

biozones by the author.

GRAPTOLITES

201-211 m Solvik Fm.
Coronograptus cf. cyphus ,
Lagavograptus ac inace si
Pribylograptus ex gr. sander soni-
incommodus. The assemblage
suggests a cyphus or gregarius
biozone (Worsley et al. 1983)

170-21 1 m Solvik Fm.
Rhaphidograptus toernquisti.
Occurs in atavus to sedgwickii
biozones (Rickards 1976)

170 m Solvik Fm. Orthograptus
obuti. Found in the Urals of
probable cyphus biozone age
(Rickards and Koren' 1974)

1 1 m Solvik Fm. dimacograptus
transgrediens Suggests latest
persculptus to earliest acuminatus
biozones (Howe 1982)

CONODONTS

Middle of Vik Fm.
Pterospatliodus pennatus
pennatus , P. amorphognathoides.
The two mark the transition
between the celloni and
amorphognathoides conodont
biozones which occurs in the
crenulata graptolite biozone of
Great Britain (Aldridge and
Mohamed 1982)

243 m Solvik Fm. Distomodus
aff. D. staurognathoides. Similar
specimens are seen in the
sedgwickii graptolite biozone of
Great Britain (Aldridge and
Mohamed 1982)

235 m Solvik Fm.

‘ Amorphognathus' tenuis.
Common in the argentus to
mid -sedgwickii graptolite
biozones in the Llandovery type
area (Aldridge and Mohamed
1982)

8-243 m Solvik Fm. Ozarkodina
oldhamensis. Has been proposed
to define the base of the Silurian
on Anticosti Island (Barnes 1982)

BRACHIOPODS

23-43 m Vik Fm. Pentamerus to
Pentameroides. The evolutionary
transition from Pentamerus to
Pentameroides is dated to the
griestoniensis graptolite biozone
in Great Britain (Ziegler et al.
1974)

64m Rytteraker Fm. Pentamerus.
Evolution of cardinalia suggests
a middle sedgwickii graptolite
biozone. (Baarli and Johnson
1982)

From 236 m Solvik Fm.
Gotatrypa liedei. Makes its first
appearance in topmost
convolutus graptolite biozone
(Copper 1982)

220 m Solvik Fm.
Eopholidostrophia cocksi cocksi.
Evolves into E. c. ultima at the
top of the convolutus graptolite
biozone in Great Britain (Hurst
1974)

environment than the lower sequence. The sections are physically correlated by frequency of storm-derivated silt
and fine sandstone interbeds which are regarded as locally synchronous.

MATERIAL AND METHODS

The Solvik Formation in the area east of Asker Station was sampled at Spirodden (grid. ref. NM826339),
Skytterveien (NM820339), and Leangbukta (NM826342) (text-fig. 1b). The three sequences are located within
2 km of each other and constitute a composite section through the upper 235 m of the complete 245 m thick
Solvik Formation. The material was retrieved mainly from 5 to 10 kg bulk samples collected at 2-5-5 0 m
intervals throughout the upper 150 m of the Solvik Formation where stricklandiids are abundant. Each bulk
sample was collected in mudstone or mudshale with a maximum thickness of 20 cm. Additional spot sampling
over a 5 m interval was done where stricklandiids appeared to be sparse. One large sample for population studies
was taken on a bedding plane.

In Sandvika spot sampling was done in a 80 m thick section through the upper part of the Myren Member and
the lowermost 70 m of the Spirodden Member of the Solvik Formation. Bulk samples of approximately 5 kg
were collected in the top 25 m of the formation. A 20 kg bulk sample was collected in the basal Vik Formation at
Kampebraten (NM848403) and spot sampling was done at the same level at Vallerkroken (NM858423).

The type material described by Williams (1951) from the Llandovery type area and the Estonian material
described by Rubel ( 1977) were also treated for comparison.

190

PALAEONTOLOGY, VOLUME 29

text-kig. I . a, districts and Silurian outcrops in the central and southern Oslo Region, Norway, b, sampling

sites and Llandovery outcrops in the Asker District.

BAARLI: SILURIAN BRACHIOPOD LINEAGE

191

The Norwegian material was disaggregated into small pieces and all shell material dissolved in 8% HC1.
Thereafter the stricklandiid material was soaked in a piolodoform bath in a pressure tank for 24 hours and dried
at I 10 °C for 4 hours to induce hardening. Latex casts were made from the brachial valve moulds of both the
Norwegian and the already prepared Llandovery material. The whole procedure involved a 20-60% loss of
material where the delicate structures in the cardinalia were destroyed. The Estonian material consisted
of shell fragments washed out from core sediment. Eight different measurements were made on the casts (in
the case of the Estonian material directly on the shells) using an eyepiece scale in the microscope at 16 x
magnification. The measurements were made without knowledge of the stratigraphic horizon whenever possible
for the Norwegian material and always for the Estonian and the Llandovery material. The measurements
include:

a, the length from the posterior point of the cardinalia to the anterior point of the outer plates.

fi, the length from the posterior point of the cardinalia to anterior point of the inner plates, where they are
fused with the brachial processes.

c, the height measured from the anterior point of the inner plates where they are fused with the brachial
process vertically down to the base of the valve floor.

d , the distance between the anterior points of the outer plates.

e, the distance between the anterolateral points where the inner plates are fused with the hingeline.

/, the distance from the posterior point of the cardinalia to the anterior point of the inner plate on the lateral
side, where it is fused with the hingeline.

g, the maximum length of the interarea.

/;, the maximum width of the brachial valve.

Where possible all these measurements were made, but the external measurements (g and /;) were often
difficult, and were impossible in the Estonian material. The populations were often small and form indexes are
used to avoid very scattered results caused by random differences in size between small populations. To
standardize, all the other measurements on the cardinalia are compared with b , a variable which by trial seemed
to undergo little change through time. This gave five form indexes: a/b, c/b , d/b, e/b , and f/b. In addition the
indexes e/g and e/h were also studied. A combination index ( a + c)/b turned out to be most useful for purposes of
practical correlation. Since external measurements are scarce, a gross check on general differences in size
through time was accomplished by clustering all specimens of each subspecies for comparison with each other.

In total, measurable latex casts were made from 391 specimens in 32 samples collected within the upper 1 50 m
of the Solvik Formation in the main Asker area. Sample size varied from 1 to 67 individuals. In addition, 79
individuals from 9 samples from the middle and upper members of the Solvik Formation, and 12 individuals
from 2 samples at the base of the Vik Formation were retrieved and measured from the Sandvika area in the
Asker District. All the Norwegian material is stored at the Palaeontological Museum in Oslo. The numerical
data are deposited with the British Library, Boston Spa, Wetherby, Yorkshire LS23 7BQ, UK as Supplementary
Publication no. SUP 14027 (63 pages).

Samples of less than five individuals were not treated statistically in the main Asker area, but were included in
the Sandvika area since material there was much scarcer. Sample mean, standard deviation, and the 95%
confident interval were calculated for each sample and form index, and then plotted against stratigraphic level
Simple tests, such as t-test for significant differences between the lowermost and uppermost sample, and the
Spearman rank test for trends, were applied to establish the statistical significance of morphological trends.

Since much phenotopic variation is represented in the material the mean of the index (a + c)/b is plotted
against number of specimens counted in four of the largest samples to test for adequate sample size (text-fig. 9).

The largest sample, at 241 m above the base of the Solvik Formation in the main Asker area, provided material
for an analysis of how the form indexes are dependent on size of the specimens. This sample was collected from a
single bedding plane and is thus closest to a natural population. The different form indexes are plotted against
maximum width and against length of the interarea. T-tests and correlation coefficients were calculated (Table 2).
If maximum width or length of interarea are taken as a measure of age, then heterochrony can be detected.

Only seventeen specimens of the Llandovery type material were treated. These include about half of the types
of the dorsal valves listed by Williams ( 1951 ). The rest were either not available or satisfactory latex casts could
not be obtained. Unfortunately none of the types of S. lens prima were available. Form indexes were calculated
and grouped relative to the subspecies erected by Williams (1951).

The Estonian material embraces 105 individuals from boreholes in nine different geographical localities. The
material was treated in the same way as the Norwegian material. Each borehole contained from two to four
subspecies. Since the boreholes can not be adequately correlated and each borehole contains few specimens, the
material was grouped in successive subspecies as determined by Rubel (1977).

192

PALAEONTOLOGY, VOLUME 29

text-fig. 2. Mean, standard deviation, and 95% confidence intervajs of form index a/b for all stricklandiid
samples with sample size 5 or more in the Solvik Formation of the main Asker area, plotted against stratigraphic
level. For comparison one sample from the Vik Formation in Sandvika is included.

BIOMETRIC ANALYSES

The main Asker area

Text-figs. 2-7 show the statistically treated form indexes for material from the main Asker area
plotted against stratigraphic level. T-tests between the lowermost sample at 95 m and the uppermost
sample at 241 m show that there is a highly significant difference in morphology between the two
samples (P < 0-001) for the form indexes a/b and c/b (text-figs. 2 and 3). This is accompanied by a
clear indication of a decreasing trend found using the Spearman rank test (P = —91 for both
samples). The t-tests also show a significant difference between lowermost and uppermost sample for
d\b and e/g {P = 0-01-0-001 and P = 0-02-0 05, (text-figs. 4 and 5) respectively). Tests by Spearman
rank indicates only a suggestion of a trend for d\b (P = —41) and no directed trend for e/g
(P = +0-16). All the other form indexes (c/6,//6, and e/h) show no significant differences between the
lowermost and uppermost sample and no indication of a directed trend (at least not if the whole
sequence is considered). They are therefore regarded as varying about a constant. The two clearest
decreasing indexes are combined in the index ( a + c)/b which shows a stronger and more even trend
than for either of the two singly. The Spearman rank is very high (P = —96) and the difference
between the lowest and highest samples is at a significance level of P < 0-001 . To help show how the
trends observed for the older parts of the main Asker section seem to continue through younger
strata, a sample from the base of the Vik Formation in Sandvika, 5 km to the north, is included in
text-figs. 2-7. The trends are clearly observed for a/b , c/6, (u + c)/6, and also <7/6.

BAARLI: SILURIAN BRACHIOPOD LINEAGE

193

text-fig. 3. Mean, standard deviation, and 95% confidence intervals of form index c/b for all stricklandiid
samples with sample size 5 or more in the Solvik Formation of the main Asker area, plotted against stratigraphic
level. For comparison one sample from the Vik Formation in Sandvika is included.

Text-figs. 7 and 8 show that there is a very large phenotypic variation within the samples for form
index ( a + c)/b . This means that the phenotypes on the periphery of different subspecies overlap and
occur at the same stratigraphic levels. Text-fig. 8 shows that the mean stabilizes at 1 5 to 20 measured
specimens and this would be a safe sample size to define the average phenotype. So large a sample,
however, is difficult to obtain and further inspection of the curves indicates a minimum requirement
of ten specimens to ensure an approximately correct form index.

An analysis of size dependence on the form indexes on one sample (Sk241) from a single bedding
plane, gave a clear correlation in only one case (Table 2). Maximum width was positively correlated
with the form index c)b (correlation coefficient of 0-5749 and a probability of near 0-001). Average
maximum width shows no clear trend through the formation (text-fig. 9). The steady decrease in c/7>
found up through the section therefore cannot be caused by a gradual change in maximum valve
width.

The Sandvika area

In the Sandvika area of the Asker District, measurable stricklandiids are found at three different
levels in the succession. There are again clear decreasing trends in a/b, c/b, (a + c)/b (text-fig. 10),
and d/b.

Comparison of the form index (a + c)lb between the main Asker area and the Sandvika area shows
that the index from the lowest level (40 to 70 m above the base of the middle Spirodden Member) is

194

PALAEONTOLOGY, VOLUME 29

text-fig. 4. Mean, standard deviation, and 95% confidence intervals of form index djb for all stricklandiid
samples with sample size 5 or more in the Solvik Formation of the main Asker area, plotted against stratigraphic
level. For comparison one sample from the Vik Formation in Sandvika is included.

table 2. Correlation between the form indexes and valve size represented by maximum width of valve FI and
maximum length of interarea G expressed by the correlation coefficient and the students t-test.

Form indexes

a/b

fib

d\b

e/b

c/b

(a + c)/b

Sample number

23

14

23

22

23

23

H, corr. coef.

01028

0-0666

0-0140

0-2100

0-5749

0-1749

T-test

-0-4957

-0-2497

-0-0673

— 1-0075

3-3698

0-8520

Sample number

41

26

41

40

41

41

G, corr. coef.

0-2764

0-1025

0-3483

0-1073

0-0592

0-2541

T-test

-1-8417

-0-5258

-2-3798

-0-6828

-0-3797

-1-6827

not equalled in the main Asker area, but falls in a gap between the indexes for material from the
uppermost Spirodden Member and lowermost part of the overlying Leangen Member. The
Spirodden Member is considerably thicker in the Sandvika area than in the main Asker area and the
probability of a diastem caused by non-deposition or erosion of the upper part of the member in the
main Asker area is thus corroborated by the observations on Stricklandia.

The next samples from the Sandvika area are found at the top of the Solvik Formation. The indexes
equal the indexes found in the top 20 m of the Solvik Formation in the main Asker area. Two samples

BAARLI: SILURIAN BRACHIOPOD LINEAGE

195

text-fig. 5. Mean, standard deviation, and 95% confidence intervals of form index e/b for all stricklandiid
samples with sample size 5 or more in the Solvik Formation of the main Asker area, plotted against stratigraphic
level. For comparison one sample from the Vik Formation in Sandvika is included.

obtained from different localities exposing the basal Vik Formation in the Sandvika area have
virtually identical form indexes.

Estonia

The Estonian material consisted of five subspecies determined semiquantitatively by Rubel (1977).
The form indexes for these five groups show a strong, steadily decreasing and directed trend for a/b
(text-fig. 1 1 ). The index c/b also decreases but shows a small reversal for the youngest taxa. Inspection
of the raw data revealed that one specimen out of the five had indexes lying far from the rest. The
result for c/b if this is omitted gives a steadily decreasing line (index = 018). The index d/b also
decreases but shows reversals. Measurements for d could be obtained from only three specimens
for each of the three youngest taxa, so the result is not very reliable. All the other measurements
varied around a constant. The results from Estonia are thus consistent with the results obtained from
the Norwegian material.

Comparison with the Llandovery type material

The measured type material consists of a very small sample with much phenotypic variation. It may
be treated statistically, however, like the Estonian and Norwegian material. The two form indexes
showing the strongest trends in the Norwegian, Estonian, and Llandovery material are ajb and c/b
(text-fig. 1 1). They correspond to two of the trends described by Williams (1951) from the Llandovery

1%

PALAEONTOLOGY, VOLUME 29

text-fig. 6. Mean, standard deviation, and 95% confidence intervals of form index///) for all stricklandiid
samples with sample size 5 or more in the Solvik Formation of the main Asker area, plotted against stratigraphic
level. For comparison one sample from the Vik Formation in Sandvika is included.

material. The decrease in a/b (or the length of the outer plates relative to the length of the inner plates)
corresponds directly to the reduction of the outer plates used by Williams (1951). The decrease in c/b
(or the vertical distance from the anterior point of the inner plates to the valve floor relative to the
length of the inner plates) is related to the decrease in angle between the inner plates and the base of
the brachial processes plus outer plates described by Williams (1951) and further stressed by Rubel
(1977). The third decreasing trend found in all material (text-fig. 1 1), index d/b, is directly related to
the index a/b since d is the distance between the anterior point of the diverging and steadily decreasing
outer plates. The form index djb shows a stronger decreasing trend in the Welsh material than both
the Norwegian and Estonian material, and the index for the Estonian material is consistently higher,
so the angle between the plates must be environmentally determined. The gradual decrease found in
fjb in the Llandovery material is not very large, and is not observed in the other material.

The size of thecardinalia in the subspecies studied by Williams (1951) shows a steady increase. This
is explained by the massive development of the inner plates and their reorientation. The size is
represented by the width of the cardinalia over the length of the interarea, and over the maximum
width of the valve, giving the two indexes e/b and e/g. The form index e/g gives no directed trend for
both areas. The form index e/h gives no directed trend for the Norwegian material. The Llandovery
material (which only comprised six measurements for this index) had about equal indexes for the
two oldest subspecies. The two youngest subspecies, however, showed a strong increase. It is
questionable that any conclusions may be drawn from these few observations and it is supposed

BAARLI: SILURIAN BRACHIOPOD LINEAGE

197

text-fig. 7. Mean, standard deviation, and 95 % confidence intervals of form index ( a + c)/b for all stricklandiid
samples with sample size 5 or more in the Solvik Formation of the main Asker area, plotted against stratigraphic
level. For comparison one sample from the Vik Formation in Sandvika is included.

that Williams (1951) based his observations of increasing size on a much larger sample observed in
the field.

A final but important feature which is not treated in this study is the impression of the muscle fields.
They become larger and deeper with time, according to Williams (1951). Rubel.(1977) considered
this, and showed that the outline and pattern of the muscle scars also changed with time. Consistent
changes have been observed non-quantitatively during this study.

TAXONOMIC DETERMINATION OF SUBSPECIES

The stricklandiid subspecies were originally described by Williams (1951) and redescribed by Rubel
(1977). The Norwegian material is assigned to subspecies accordingly. The indexes used in this study
for the subspecies samples from the three geographic regions may be compared with one another to
test their validity for taxonomic use.

The Norwegian material often lacks features used in the definitions of subspecies such as the shape
of the interarea, impression of the muscle fields, and presence or absence of fold and sinus. The size of
cardinalia (used by Williams ( 1951)) is shown to be invalid for taxonomical use in Stricklandia in this
study. The subspecies, as redefined by Rubel (1977), are still possible to distinguish in the Norwegian
material, except for the two oldest. The definitions of these are difficult to apply to this material.
Williams (1951) explicitly stated that the outer plates extend beyond the line of fusion with the
brachial process in S. lens prima while they were only moderately long in the youngest subspecies. It

198

PALAEONTOLOGY, VOLUME 29

text-fig. 8. Mean, standard deviation, and 95% confidence intervals of form index ( a + c)/b for all stricklandiid
samples with sample size 5 or more in the Solvik and Vik formations in Sandvika. 95% confidence intervals are

not shown for smaller samples.

a ♦ c

b

text-fig. 9. Dependence of sample size on the form index ( a + c)/b shown for the largest samples at different
levels up through the Solvik Formation of the main Asker area.

BAARLI: SILURIAN BRACHIOPOD LINEAGE

199

FORMATION

Leangen Member

£50'
M .

200'

e we ><se» ®o* se w • ® ® ® ®

0 0 0 0 0 «Ss 0 0

« • 0 • ®

0 0 0 0 0

. ’ \ Stricklandia lens progressa

\

* \

V

V

\

\ Stricklandia lens intermedia

\

\

\ •

>

c

0

-O

150'

\ Stricklandia lens lens

_l

~o

• • • . /

vJ

CO

'a

• • j 0 0

CO

*

/ *

c

0

v_

/

* — Stricklandia lens prima

5

100

j 0 0 0 0 0

01 2 3 4 5 cm

Maximum width of valve — ►

text-fig. 10. Single measurements and mean with standard deviation of maximum width of valve of subspecies

plotted against stratigraphic level.

is, therefore, here proposed to add to the diagnosis that S. I. prima displays outer plates extending
anteriorly beyond their fusion with the brachial process.

S. lens first occurs 1 1 m above the base of the Solvik Formation in the central Asker district (i.e.
very near the base of the Silurian). No samples less than 95 m above the base were sufficiently large or
well enough preserved to allow measurement for identification to subspecies. The samples from 95 m
to 168 m above the base of the Solvik Formation show completely gradual changes in internal
features. The lowest sample at 95 m above the formational base is the only one showing good external
features. The specimens all have a very distinct fold and sinus. On this basis they belong to S. I. prima.
All specimens from 95-0 m to 1 22-5 m have outer plates which extend far beyond their fusion with the
brachial processes, while a few specimens above show shorter outer plates. There are very slight
differences in samples from this level to 132-5 m above the formational base. The level at 122-5 m
is chosen, however, to represent the uppermost limit of the subspecies S. I. prima as redefined here.
S. I. lens occurs up to 168 m above the base of the Solvik Formation.

There is a pronounced difference in morphology between the specimens found up to 168 m above
the formational base in the Spirodden Member and those found stratigraphically above in the
Leangen Member. The reason for this is probably a diastem in the main Asker area. The specimens in
the basal Leangen Member belong without a doubt to 5. /. intermedia. The stratigraphic section of the
Sandvika area is probably more complete and stricklandiids here are of an intermediate type. The
available material is judged to belong to S. I. intermedia. A part of the range of this species is therefore
missing in the main Asker area.

200

PALAEONTOLOGY, VOLUME 29

• Norway

. ^ S. laevis ..

1

" vv a 1 e s

time * v

- □ Estonia

s.

lens progressa

• "-05^.

S. lens intermedia

a

»

— S.lens lens

\

\ ^ ^

b

□ v " s. lens prima

CK8 0T9 iTo 1.1 1T2 1T3 1T4 1 .'5 a/b

text-fig. 1 1. Plots of form index a/b, c/b , djb , and (a + c)/b for succeeding stricklandiid subspecies from main
Asker area in Norway, Wales, and Estonia. The distances between the stricklandiid subspecies are kept equal

without regard to actual time.

BAARLI: SILURIAN BRACHIOPOD LINEAGE

201

The transition to the next overlying subspecies is again very gradual and difficult to delimit. At
230 m above the formational base the populations belong to S. I. progressa , while the populations
under 192 m above the formational base clearly belong to S. I. intermedia. The transition is somewhat
arbitrary but there seems to be a majority of specimens with laterally wide splaying plates
characteristic of the youngest subspecies from 202-5 m above the formational base. Specimens with
degenerate outer plates are also observed, although very seldom from this level on.

The subspecies S. laevis is not found in the main Asker area but the specimens found at the base of
the Vik Formation in the Sandvika area of the Asker district belong without any doubt to this species.
The different Norwegian subspecies are shown in Plate 21.

The form indexes may be used to support the validity of stricklandiid subspecies in Norway as
compared with Llandovery and Estonia. Text-fig. I I plots the average form indexes of the different
subspecies from the main Asker area in Norway, Llandovery, and Estonia for a/b. cjb. and d\b and
for the combination ( a + c)/b . All plots of form indexes lie within the standard deviation of the
Norwegian material, and most plot very close together. The Estonian material has lower values for
the indexes a/b and c/b for S. lens prima than seen in Norway. This may be the result of a shorter time
interval represented by this subspecies (i.e. only the top range of 5. lens prima). This is not possible to
prove, however, with the available data. The very high value found for S. laevis in Estonia is
influenced by one deviating specimen in a small sample, as discussed above.

Considering the small sample sizes in the Llandovery material and the exceptional cases explained
above the indexes support the designation to subspecies made in Norway.

The best fit for all subspecies is seen for the index ( a + c)/b . This form index therefore may be used
to determine and distinguish subspecies more accurately, where the size of the sample is adequate.

SIMULTANEOUS OCCURRENCE IN WALES AND NORWAY

The two oldest types for Stricklandia in Wales come from the southern part of the Llandovery area
where no determinative graptolites are known. Cocks et at. (1984) suggest a stratigraphic range for
the lineage S. lens/S. laevis from the base of the acinaces graptolite biozone to mid -griestoniensis
graptolite biozone, where Costistricklandia Ur at a takes over the succession. Stricklandia in Norway
ranges from earliest Silurian time (late persculptus to early acuminatus graptolite biozone) to
somewhere between the turriculatus and mid -griestoniensis graptolite biozones. Thus the upper limits
of the lineage are coeval in Norway and Wales, while the first occurrence in Norway probably
predates the oldest known representatives in Wales.

In the Llandovery area only the S. lens progressa to S. laevis and S. laevis to C. lirata transitions
are well defined. None of the lower subspecies are found directly succeeding one another and only
the biostratigraphic position of Williams’s type specimens are implied (Cocks et al. 1984). In Norway
the lowest four subspecies are found succeeding each other, while the upper transitions are not
recognized.

The types of S. lens prima and S. I. lens are both placed in the cyphus graptolite biozone in the
Llandovery area by Cocks et al. (1984). The same transition, based on a redefined S. I. prima , is set in
Norway at 122-5 m above the base of the Solvik Formation. This may also occur in the cyphus zone,
since the nearest datable stratum 1 70 m above the base is certainly younger than the uppermost atavus
biozone, and probably as young as the cyphus biozone.

The transition between S. I. lens and S. I. intermedia is proposed in Norway at a horizon 168 m
above the base of the Solvik Formation. Again this is probably within the cyphus graptolite biozone
in Norway. The type of S. I. intermedia is found in the convolutus biozone, but Williams (1951)
indicated that it ranges down to the top of the Rhuddanian or the cyphus biozone.

S. I. progressa is found in the Rhydings and Wormwood formations within the sedgwickii to lower-
most turriculatus biozones (Cocks et ah 1984). The transition between this subspecies and the under-
lying S. I. intermedia must therefore occur within the convolutus biozone. The transition in Norway
cannot be younger than the gregarius graptolite biozone. The very gradual transition could, however,
justify a boundary set considerably higher up in the section perhaps into the convolutus biozone.

202

PALAEONTOLOGY, VOLUME 29

S. laevis found in Norway occurs at a level which is correlated to the turriculatus biozone and is well
within the range of this species in Wales.

The correlation between Norway and Wales is hard to corroborate because of poor graptolite
records in both areas. There is, however, no definite proof of a disparity in age for any of the taxa and
the coincidental occurrence of the youngest taxa would deny the existence of a geographical cline.

SUMMARY AND CONCLUSIONS

1. The section in the main Asker area displays the four subspecies S. lens prima , S. I. lens , S. I.
intermedia , and S. /. progressa in a continuous succession. The Sandvika area provides the lower
range of S. I. intermedia missing in the main Asker area.

2. Plots of form indexes a/b and c/b grouped in subspecies after the definition of Rubel (1977)
correlate well for Norway, Estonia, and Wales. Form index (a + c)/b serves even better and may
therefore be used as a biometric tool for determination of subspecies.

3. The total range of the stricklandiid lineage is roughly coeval in Wales and Norway. The
subdivisions of the lineage S. lens/S. laevis may be temporally equivalent as well. No evidence for a
geographic cline is observed.

4. Phenotypic variation within the populations are so large that phenotypes on the periphery of
succeeding subspecies occur together. Preferred sample size should ideally be fifteen to twenty
specimens with a minimum of ten specimens to ensure a reliable index mean.

5. The same decreasing trends in form indexes a/b , c/b , and d/b are found in two Norwegian
sections, in Estonia, and in the Llandovery area of Wales. Form indexes a/b and c/b fall within the
same range for the four sections, while djb have different but always decreasing ranges. The
combination index (a + c)/b gives the cleaest and strongest trend, with high correlation in the four
investigated areas.

6. The only form index depending on valve size is c/b which shows a positive correlation. Valve size
shows no trend up through the section and therefore cannot cause the observed decreasing trend in
c/b which therefore is regarded to be evolutionary.

7. The trends expressed by form indexes a/b and c/b correspond to trends used by Williams (1951)
and Rubel (1977) to distinguish stricklandiid subspecies. These are: 1, the outer plates are reduced
relative to the inner plates; 2, the angle between inner plates and the bases of the brachial processes
plus outer plates decreases.

8. The trend in increasing size of the interarea described by Williams (1951) and used to designate
subspecies is not found in the Norwegian material and is regarded as environmentally controlled and
invalid for discrimination of subspecies.

Most of the criteria of Gould and Eldredge (1977) for adequate tests on evolutionary models are
met in this study. Two of the same decreasing trends are tested and found to occur within the same

EXPLANATION OF PLATE 21

Figs. 1 and 2. Stricklandia lens prima (Williams). Latex casts of brachial valve moulds, Solvik Formation,
Spirodden, Asker. 1, P.M. 0.108291, 1 17-5 m above the formational base, x 6; 2, P.M.0. 105246, 95 m above
the formational base, x 8.

Figs. 3 and 4. S. I. lens (Sowerby). Latex casts of brachial valve moulds, Solvik Formation. 3, P.M.0. 108292,
130 m above the formational base, Spirodden, Asker, x 6; 4, P.M.0. 105852, 155 m above the formational
base, Skytterveien, Asker, x 6.

Fig. 5. S'. /. intermedia (Williams). Latex cast of brachial valve mould. P.M.0. 108293, 180 m above the base of the
Solvik Formation, Skytterveien, Asker, x 6.

Figs. 6 and 8 S. I. progressa (Williams). Latex casts of brachial valve moulds. 230 m above the base of the Solvik
Formation, Leangbukta, Asker. 6, P.M.0. 105252, x 6; 8, P.M.0. 108320, x 6.

Fig. 7. S. laevis (Sowerby). Latex cast of brachial valve mould. P.M.O. 105254, 0-4 m above the base of the Vik
Formation, Kampebraten, Sandvika, x 8.

PLATE 21

BAARLI, Stricklandia

204

PALAEONTOLOGY, VOLUME 29

range in three widely separated areas under different sedimentary conditions. Williams’s definition
(1951) of stricklandiid subspecies withstands rigorous testing in all but one respect: size increase of
the cardinalia through time. The Norwegian stratigraphic sequences are long and provide reasonably
large samples, alhough not large or closely spaced enough to reveal with certainty the fine details of
micro-evolution.

The evolution of Stricklandia\Costistricklandia is generally considered to be phyletic (Boucot
1975; Johnson 1979). Due to unavoidably coarse sample intervals this study cannot test that view
with statistical certainty for any of the studied sections. The exhibited trends are, however, found in
four different sections. They are seemingly gradual, linear, and simultaneous over a wide geographic
area, and strongly suggestive of orthoselection and possibly phyletic gradualism. Whatever the fine-
scale pattern of evolution is, the StricklandiajCostistricklandia lineage has been, and still is, of prime
importance for the biocorrelation of shelly faunas in Llandovery sections all over the world.

Acknowledgements. Special thanks are due to my supervisor D. Worsley and the staff of the Palaeontological
Museum, Oslo, where most of this work was carried out. M. Rubel kindly gave me access to his collections at the
Institute of Geology, Academy of Science of the Estonian SSR. M. Dorling at the Sedgwick Museum,
Cambridge, provided the Llandovery type material and M . E. Johnson helped with the language and discussions
at various stages of this study. Finally, I wish to acknowledge the financial support of NAVF, the Norwegian
Research Council for Science and Humanities.

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-and colville, v. r. 1981. Regional integration of evidence for evolution in the Silurian Pentamerus-
Pentameroides lineage. Lethaia , 15, 41 54.

kaljo, D. 1979. Silurian stratigraphy of the Baltic region and related stratotypes. Acad. Naiik. Kaz. SSR. Izv. Ser.
Geol. Nos 4 7, 107-115. [In Russian ]

Ki/ER, j. 1908. Das Obersilur im Kristianiagebiete. Skr. Vidensk. Se/sk. Christiania I Mat. Naturv. Kl. 1906 (2),
596 pp.

rickards, R. B. 1976 The sequence of Silurian gratolite zones in the British Isles. Geol. J. 11, 153-188.

— and koren', t. n. 1974. Virgellar meshworks and sicular spinosity in Llandovery graptoloids. Geol. Mag.
Ill, 193-272.

rubel, m. 1977. Evolution of the genus Stricklandia (Pentamerida, Brach.) in the Llandovery of Estonia. In
kaljo, D. (ed.). Facies and fauna of the Baltic Silurian , 286 pp. Acad. Sci. Estonian SSR, Inst. Geol. Tallinn.
sadler, p. m. 1981. Sediment accumulation rates and the completeness of stratigraphic sections. J. Geol. 89,
569-584.

ST. JOSEPH, J. k. s. 1935. A critical examination of Stricklandia ( = Stricklandinia) lirata (J. de C. Sowerby, 1939)
forma typica. Geol. Mag. 72, 401-424.

— 1938. The Pentameracea of the Oslo Region. Nor. Geol. Tidsskr. 17, 225-336.
schindel, d. E. 1982. Resolution analysis: A new approach to the gaps in the fossil record. Paleobiology , 8,
340-353.

williams, a. 1951. Llandovery brachiopods from Wales with special reference to the Llandovery district. Q. Jl
geol. Soc. Land. 107, 85- 136.

worsley, d., aldridge, r. j., baarli, b. G., howe, m. p. a. and Johnson, m. e. 1983. The Llandovery Series of the
Oslo Region. IUGS Subcommission on Silurian Stratigraphy. Paleont. contr. Unix. Oslo , 287, 38 pp.
ziegler, a. m. 1966. The Silurian brachiopod Eocoelia hemisphaerica (J. de C. Sowerby) and related species.
Palaeontology , 9, 523-543.

— rickards, r. b. and mckerrow, w. s. 1974. Correlation of the Silurian rocks of the British Isles. Geol. Soc.
Am. Spec. Pap. 154, 154 pp.

B. GUDVEIG BAARLI
Paleontologisk Museum
Sarsgate 1, Oslo 5
Norway

Present address:
Department of Geology

Typescript received 2 January 1985 Williams College, Williamstown

Revised typescript received 18 June 1985 01267 Mass., USA

SECONDARY NANOZOOECIA IN SOME UPPER
PALAEOZOIC FENESTRATE BRYOZOA

by ADRIAN J. BANCROFT

Abstract. Autozooecial apertures sealed by perforate terminal diaphragms have been found in eleven species of
British and Irish Carboniferous and Permian fenestrate Bryozoa. In their skeletal morphology, intra-colonial
abundance, and distribution they resemble the perforate terminal diaphragms of polymorphs that are termed
secondary nanozooecia in the Recent tubuloporinid cyclostome Plagioecia and the lichenoporid cyclostome
Disporella. The former presence in fenestrates of single-tentacled non-feeding polymorphs comparable to those
of Plagioecia and Disporella is inferred. As in Plagioecia and Disporella , secondary nanozooecia of fenestrate
bryozoans may represent a late stage of zooidal ontogeny. The function of secondary nanozooecia in Plagioecia
and Disporella is unknown, but those of fenestrates possibly had a defensive/cleaning function comparable to
that suggested for primary nanozooids in the Recent tubuloporinid cyclostome Diplosolen obelium.

Fenestrate Bryozoa (Class Stenolaemata Borg, 1926; Order Fenestrata Elias and Condra, 1957)
were once considered to be monomorphic. However, recent morphological studies have revealed the
existence of a variety of skeletal structures which have been interpreted as reflecting the occurrence of
several types of polymorphic zooids. Certain types of polymorphic zooecia are reasonably well
documented in fenestrates, e.g. brood chambers (Tavener-Smith 1966; Engel 1975; Stratton 1975,
1981; Southwood 1985) and accessory pores (Nikiforova 1938; Shulga-Nesterenko 1941, 1952;
Shishova 1970), but inferred secondary nanozooecia have hitherto been described in only one taxon,
Lyroporella quincuncialis (Hall), from the Carboniferous of the USA (McKinney 1977).

During a recent revision of British and Irish Carboniferous Bryozoa, skeletal structures that
resemble the perforate terminal diaphragms of secondary nanozooecia in certain Recent Bryozoa
(the tubuloporinid cyclostome Plagioecia , the lichenoporid cyclostome Disporella , and L. quin-
cuncialis) have been found to occur in eight species of fenestrate Bryozoa. Identical structures have
also been recently found in three species of Upper Permian fenestrate Bryozoa from the Middle
Magnesian Limestone (reef facies) of County Durham, England (D. A. Southwood, pers. comm.).
The abundance of the material available and the occurrence of these structures in a number of taxa
has allowed a detailed analysis of their morphology and interpretation of their functional significance.
Cited material is located in the collections of the British Museum (Natural History).

RECENT SECONDARY NANOZOOECIA

Primary nanozooecia were first described in detail by Borg ( 1 926) in the living cyclostome Diplosolen
Borg and are morphologically and functionally reasonably well known. Secondary nanozooecia,
however, have only recently been documented by Silen and Harmelin (1974) in the living
tubuloporinid cyclostome Plagioecia and by Moyano (1982) in the living lichenoporid cyclostome
Disporella. Although the soft part morphology of primary and secondary nanozooids is comparable,
primary nanozooids are budded from the outset as polymorphic zooids whereas secondary
nanozooids are intra-zooidal, that is ontogenetic polymorphs developed within the chamber of a
degenerated autozooid.

Colonies of Plagioecia and Disporella are adnate and secondary nanozooecia are developed in
older parts of the colonies. They represent a late stage of ontogenetic development. According to
Silen and Harmelin ( 1 974, p. 93) the development of a secondary nanozooid takes the following path.

[Palaeontology, Vol. 29, Part 1, 1986, pp. 207-212]

208

PALAEONTOLOGY, VOLUME 29

Following the degeneration of the autozooecial polypide only the atrial sphincter and the proximal
part of the zooid remain unchanged. A perforate terminal diaphragm, with a single small circular
secondary aperture, is calcified cenlripetally over the original autozooecial aperture. The secondary
aperture is slightly elevated above the level of the terminal diaphragm by a peristome-like rim (Silen
and Harmelin 1974, figs. 16 and 17.). A new polypide with a different morphology is then regenerated.
All parts are smaller, the alimentary canal is rudimentary, and there is a single non-ciliated tentacle.
When protruded the tentacle is very short and extends vertically from the secondary aperture (Silen
and Harmelin 1974, figs. 16-20).

Although these authors made observations on the behaviour and morphology of secondary
nanozooids in Plagioecia , they did not reach any conclusions as to their functional significance. They
did however exclude a feeding function, because of the lack of cilia on the tentacle, and a cleaning
function analogous to that of primary nanozooids in Diplosolen obelium (Johnston) because the
tentacle is too short and inappropriately orientated. They also found no evidence of any male cells,
glands, or other special organs.

FENESTRATE SECONDARY NANOZOOEC1A

In fossil Bryozoa, calcified perforate terminal diaphragms with elevated secondary apertures sealing
autozooecial apertures have only been recognized and interpreted as representing the terminal
diaphragms of secondary nanozooecia in the Carboniferous fenestrate L. quincuncialis (Hall)
(McKinney 1977). However, several authors have illustrated and described similar structures
comparable with the perforate terminal diaphragms of secondary nanozooecia in Plagioecia and
Disporella in other Carboniferous fenestrate taxa. Young (1879, p. 212) described the occurrence of
cell pores covered by a thin calcareous disc or diaphragm pierced in the centre by a very minute pore
in Fenestella plebeia M'Coy, F. ejuncida M'Coy, Polypora tuberculata Prout, and Penniretepora
elegans (Young and Young). He believed that this structure was a condition of the perfectly preserved
cell pore in these taxa. Zittel (1895), in diagnosing the Family Fenestellidae King, described the
structure of zooecial apertures when perfectly preserved as being covered by centrally perforate
closures. Tavener-Smith (1969, pi. 54, figs. 4 and 5; text-fig. 9) illustrated the peristomial funnels of
secondary nanozooecia in longitudinal section, in the Carboniferous fenestrates Lyropora
quincuncialis Hall and L. subquadrans (Hall). Most recently Tavener-Smith (1973, p. 459) described
autozooecial apertures in some specimens of F. polyporata (Phillips) as being sealed by a translucent
plate-like deposit, sometimes incomplete and pierced by a small central orifice.

During a recent revision of British and Irish Carboniferous fenestrate Bryozoa (Bancroft 1984)
identical structures have been found to occur in another four taxa in addition to those mentioned
by Young and Tavener-Smith. These are Penniretopora flexicarinata (Young and Young),
P. pulcherrima (M'Coy), Ptylopora pluma M'Coy, and Polypora dendroides M'Coy. They have also
been found to occur in three Upper Permian fenestrate taxa from the Middle Magnesian Limestone
(reef facies) of County Durham, England: Penniretepora waltheri (Korn), Synocladia virgulacea
(Phillips), and F. retiformis (Sclotheim) (D. A. Southwood, pers. comm.).

The morphology of perforate terminal diaphragms in all these taxa is comparable and there is only
slight morphological variation within a species (text-fig. 1). All consist of a thin lamina sealing the
autozooecial aperture, at a level immediately below the crest of the peristomial rim, or the branch
surface in taxa without peristomes, and are perforated by a very small approximately centrally
positioned secondary aperture. Secondary apertures range between 0 010 mm and 0 021 mm in
diameter, and while in P. pulcherrima the perimeter of the secondary apertures form low, well-
rounded, thick peristomes (text-fig. lc, f), in all other taxa secondary apertures are elevated above the
level of diaphragms by distally narrowing funnel-shaped peristomes (text-fig. Id). The surface of
diaphragms is usually flat and smooth, except in P. pulcherrima in which the perimeter of the
diaphragm is ornamented by a single row of closely spaced small circular pustules (text-fig. If).

Tavener-Smith (1973, p. 459) noted the occurrence of these structures in the proximal parts of
colonies of F. polyporata. However, while terminal diaphragms appear to be particularly abundant in

BANCROFT: SECONDARY NANOZOOECIA IN FENESTRATE BRYOZOA

209

text-fig. 1 . SEMs of Upper Palaeozoic Bryozoa showing autozooecial apertures sealed by a perforate terminal
diaphragm, a, d, Penniretepora elegans (Young and Young), BM(NEI) PD. 6282. Lower Limestone Group,
Hosie Limestones (Visean, Brigantian), Hairmyres, East Kilbride, Scotland, a, x 20; D, x 160. B, E, Synocladia
virgulacea (Phillips) BM(NH) PD. 6285. Middle Magnesian Limestone, reef facies (Upper Permian), Ryhope,
Sunderland, Tyne and Wear, England, b, x 28; e, x 178. c, f, P. pulcherrima (M‘Coy), BM(NH) PD. 6284.
Lower Limestone Group, Hosie Limestones (Visean, Brigantian), Hairmyres, East Kilbride, Scotland, c, x 26,

f, x 190.

the extreme proximal parts of fenestrate colonies, in several large colony fragments of 5. virgulacea
they extend further distally: colonies may possess perforate terminal diaphragms sealing autozooecial
apertures up to more than 10 cm from the colony origin.

Functional interpretation

The occurrence of perforate terminal diaphragms in several Upper Palaeozoic fenestrate taxa,
comparable in morphology to the perforate terminal diaphragms of living secondary nanozooecia in
Plagioecici and Disporella , suggests the existence of a polymorphic zooid analogous to the single

210

PALAEONTOLOGY, VOLUME 29

tentacled secondary nanozooids of Plagioecia and Disporella (McKinney 1977). McKinney
suggested that such a single-tentacled polypide in fenestrates may have functioned as a male
polymorph as inferred for some Recent cheilostome zooids with a reduced number of tentacles (after
Cook 1968). However, this function is possibly limited to mobile lunulitiform cheilostomes where
long single-tentacled male zooids almost appear to copulate with maternal zooids. The intra-colonial
abundance and distribution of perforate terminal diaphragms, and the small size of secondary
apertures in fenestrates, possibly does not favour such a role.

As in Plagioecia and Disporella , fenestrate secondary nanozooecia were possibly a late stage of
zooidal ontogenetic development (Tavener-Smith 1973, p. 459; McKinney 1977, p. 96). Those
observed by McKinney were completely covered over by laminated skeletal deposits in the proximal
heavily thickened margin of Lyroporella soon after their development. However, although proximal
areas of fenestrate colonies are susceptible to additional deposition of laminated skeletal material,
which served to strengthen the basal areas of large reticulate or pinnate colonies, only a few terminal
diaphragms in the extreme proximal parts of colonies examined in the present study were seen to be
completely covered by laminated skeletal deposits.

McKinney suggested that the single-tentacled polypides of fenestrate secondary nanozooecia may
have performed some kind of defensive/cleaning function shown by Silen and Harmelin (1974) for

D

/

A

— Sealed autozooecial
apertor®

secondary nanozooid
tentacle

e

/^surface area covered
^ ' by a tentacle

text-fig. 2. A-c, Diplosolen
obelium (Johnston), redrawn from
Silen and Harmelin (1974). a,
autozooid and primary nanozooids
withtheirtentaclesextended, x 120.
b, c, movement of a nanozooid
tentacle, x 120. d, areas covered
by the action of fenestrate secon-
dary nanozooid tentacles projected
on a colony surface in the fenes-
trate genus Fenestella Lons-
dale, x 40.

BANCROFT: SECONDARY NANOZOOECIA IN FENESTRATE BRYOZOA

211

primary nanozooids of Diplosolen obelium. In D. obelium colonies the single tentacle protruded from
the aperture of the nanozooecium is long. It extends in a horizontal plane and performs a periodic
proximal to distal motion or sweeping circular motion (text-fig. 2 a-c). Silen and Harmelin showed
that these movements facilitated the clearance of mud particles from the colony surface.

It is quite possible that fenestrate secondary nanozooids had a function comparable to that of
primary nanozooids in D. obelium , and that they facilitated the removal of sediment particles and
prevented the settlement and attachment of larvae of other organisms on the obverse surface of
branches. Primary nanozooecia are equidistant in colonies of D. obelium , and Silen and Harmelin
(1974, fig. 15) showed that the movement of nanozooid tentacles was such that almost the entire
surface area of the colony would be situated within reach of them. In fenestrates, autozooecial
apertures only open on one side of the meshwork, the obverse or frontal surface, are equidistant and
alternately arranged in longitudinal rows on branches. As in D. obelium it is possible to envisage that
almost the entire obverse surface of branches in the proximal portion of a fenestrate colony would be
situated within reach of secondary nanozooid tentacles (text-fig. 2d). The inferred defensive/cleaning
function of fenestrate secondary nanozooids may not have been necessary in other parts of the colony
where active autozooids created powerful feeding currents that scoured obverse branch surfaces. It is
also possible that fenestrate autozooids may have utilized particle rejection mechanisms similar to
those of many living gymnolaemates to facilitate the removal of unwanted particles. The action of
secondary nanozooids and autozooids possibly explains the reason why the reverse surface of
branches are more commonly found encrusted by parisitic organisms, such as serpulids and adnate
Bryozoa, than the obverse surface.

The distribution of perforate terminal diaphragms in fenestrate colonies suggests that the
morphologic change from autozooid to nanozooid was probably age related as in Plagioecia and
Disporella. In mature colonies of Plagioecia and Disporella the largest portion of the colony surface is
comprised of secondary nanozooecia (Silen and Harmelin 1974; Moyano 1982). Unfortunately, the
growth rate of fenestrate bryozoans is undetermined, and it is not possible to tell the relative age of
colony fragments solely on the relative abundance of secondary nanozooecia.

CONCLUSIONS

1. Perforate terminal diaphragms sealing autozooecial chambers in fenestrates are comparable in
morphology, distribution, and relative abundance to identical structures sealing autozooecial
chambers and occupied by non-feeding polymorphs (secondary nanozooids) in the Recent
tubuloporinid cyclostome Plagioecia and the lichenoporid cyclostome Disporella.

2. In fenestrates, autozooecial chambers sealed by such structures may also have been occupied by
single-tentacled non-feeding polypides comparable to secondary nanozooids in Plagioecia and
Disporella.

3. As in Plagioecia and Disporella , fenestrate secondary nanozooecia may represent a late stage of
zooidal ontogenetic development.

4. Fenestrate secondary nanozooids possibly had a defensive/cleaning function comparable to
primary nanozooids in the Recent tubuloporinid cyclostome Diplosolen obelium.

Acknowledgements. 1 thank Dr G. P. Larwood, Department of Geological Sciences, University of Durham, for
critically reviewing an early draft of this manuscript, and Dr P. D. Taylor, British Museum (Natural History),
for advice given during preparation of a revised draft. I am grateful to Mr D. A. Southwood, Department of
Geological Sciences, University of Durham, for kindly allowing me make reference to his Permian material. This
work was carried out during the tenure of a Natural Environment Research Council studentship at the
Department of Geological Sciences, University of Durham.

REFERENCES

Bancroft, a. j. 1984. Studies in Carboniferous Bryozoa. Ph.D. thesis (unpubl.), University of Durham.
borg, F. 1926. Studies on Recent cyclostomatous Bryozoa. Zool. Bidr. Upps. 10, 181-507.

212

PALAEONTOLOGY, VOLUME 29

cook, p. L. 1968. Observations on living Bryozoa. Atti. Soc. It. Nat. e Museo Civ. St. Nat. Milano , 108, 155-160.
elias, m. k. and condra, g. e. 1957. Fenestella from the Permian of West Texas. Mem. Geol. Soc. Am. 70, 1 158.
engel, b. a. 1975. A new ?bryozoan from the Carboniferous of Eastern Australia. Palaeontology, 18, 571-605.
mckinney, F. K. 1977. Functional interpretation of lyre-shaped Bryozoa. Paleobiology, 3, 90-97.
moyano, H. i. 1982. Genus Disporella Gray, 1848; Two new Chilean species (Bryozoa, Cyclostomata,
Disporellidae). Bol. Soc. Biol, cle Concepcion, Chile, 53, 71-77.

Nikiforova, a. I. 1938. Types of Carboniferous Bryozoa of the European part of the U.S.S.R. In Acad. Sci.
U.S.S.R. 1 -290. [In Russian.]

shishova, n. a. 1970. Some new Silurian and Devonian bryozoans of Mongolia. In New species of Paleozoic
Bryozoa and corals. Izd-vo. Nauka. 28-31. [In Russian ]
shulga-nesterenko, m. i. 1941. Lower Permian Bryozoa of (he Urals. Akad. Nauk. S.S.S.R. Trudy Pa/eontol.
Inst. 5, 1-226. [In Russian ]

1952. New Lower Permian bryozoans of Cisuralia. Akad. Nauk. S.S.S.R. Trudy Paleontol. Inst. 37, 1-84.
[In Russian.]

silen, l. and harmelin, j. g. 1974. Observations on living Diastoporidae (Bryozoa Cyclostomata) with special
regard to polymorphism. Acta. Zool. 55, 81 -96.

southwood, d. a. 1985. Ovicells in some Fenestrata from the Permian of N.E. England. In nielsen, c. and
larwood, G. P. (eds.). Bryozoa Ordovician to Recent. Olsen and Olsen, Fredensborg.
stratton, J. F. 1975. Ovicells in Fenestella from the Speed Member, North Vernon Limestone (Eifelian, Middle
Devonian) in Southern Indiana, U.S.A. Doe. Lab. Geol. Sci. Lyon., H.S. 3 (Fasc. 1), 169-177.

1981. Apparent ovicells and associated structures in the fenestrate bryozoan Polypora shumardii Prout. J.
Paleont. 55, 880-884.

tavener-smith, r. 1966. Ovicells in fenestrate cryptostomes of Visean age. Ibid. 40, 190-198.

1969. Skeletal structure and growth in the Fenestellidae (Bryozoa). Palaeontology , 12, 281-309.

1973. Fenestrate Bryozoa from the Visean of County Fermanagh, Ireland. Bull. Br. Mus. Nat. Hist. (Geol.),
23, 389-493.

young, j. 1 879. Notes on the perfect condition of the cell pores and other points of structure in certain species of
Carboniferous Polyzoa from Western Scotland. Trans. Geol. Soc. Glasg. 6, 21 1-217.
zittel, K. A. 1 895. Textbook on Paleontology ( 1 927 translation, revised and enlarged edition), 53 1 pp. Macmillan
and Co., London.

A. J. BANCROFT

Department of Geology
Trinity College

Typescript received 22 April 1985 Dublin 2

Revised typescript received 10 June 1985 Ireland

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Palaeontology

VOLUME 29 • PART 1

CONTENTS

Molecular palaeontology

BRUCE RUNNEGAR 1

The ammonite fauna of the Calcaire a Baculites (Upper
Maastrichtian) of the Cotentin Peninsula (Manche, France)

W. J. KENNEDY 25

Palaeoecology and history of the Calceocrinidae (Palaeozoic
Crinoidea)

WILLIAM I. AUSICH 85

Solar cyclicity in the Precambrian microfossil record

ZHANG ZHONGYING 101

A review of Antarctic ichthyofaunas in the light of new fossil
discoveries

LANCE GRANDE and JOSEPH T. EASTMAN 113

Shell structure, growth, and functional morphology of an
elongate Cretaceous oyster

KIYOTAKA CHINZEI 139

Ovicells in the Palaeozoic bryozoan Order Fenestrata

ADRIAN J. BANCROFT 155

New Triassic sphenodontids from south-west England and
a review of their classification

N. C. FRASER Q 165

A biometric re-evaluation of the Silurian brachiopod lineage
Stricklandia lens I S. laevis

B. GUDVEIG BAARLI 187

Secondary nanozooecia in some Upper Palaeozoic fenestrate
Bryozoa

ADRIAN J. BANCROFT 207

Primed in Green Britain at the University Printing House , Oxford
by David Stanford, Printer to the University

issn 00.11 0239

THE PALAEONTOLOGICAL ASSOCIATION

The Association was founded in 1957 to promote research in palaeontology and its allied sciences.

COUNCIL 1986-1987

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London SW7 5BD

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Dr. D. E. G. Briggs, Department of Geology, University of Bristol, Bristol BS8 1 RJ
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Editors

Dr. P. R. Crowther, Leicestershire Museums Service, Leicester LEI 6TD
Dr. D. Edwards, Department of Plant Science, University College, Cardiff CF1 1XL
Dr. L. B. Halstead, Department of Geology, University of Reading, Reading RG6 2AB
Dr. T. J. Palmer, Department of Geology, University College of Wales, Aberystwyth SY23 2AX
Dr. C. R. C. Paul, Department of Geology, University of Liverpool, Liverpool L69 3BX
Dr. P. A. Selden, Department of Extra-Mural Studies, University of Manchester, Manchester M13 9PL

Other Members

Dr. H. A. Armstrong, Newcastle upon Tyne Dr. M. E. Collinson, London

(plus two vacancies)

Overseas Representatives

Australia: Professor B. D. Webby, Department of Geology, The University, Sydney, N.S.W., 2006
Canada: Dr. B. S. Norford, Institute of Sedimentary and Petroleum Geology, 3303-33rd Street NW., Calgary, Alberta
Japan : Dr. I. Hayami. University Museum, University of Tokyo, Hongo 7-3-1, Bunkyo-Ku, Tokyo
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U.S. A.: Dr. R. J. Cuffey, Department of Geology, Pennsylvania State University, Pennsylvania 16802
Professor A. J. Rowell, Department of Geology, University of Kansas, Lawrence, Kansas 66045
Professor N. M. Savage, Department of Geology, University of Oregon, Eugene, Oregon 97403
South America: Dr. O. A. Reig, Departamento de Ecologia, Universidad Simon Bolivar, Caracas 108. Venezuela

MEMBERSHIP

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There is no admission fee. Correspondence concerned with Institutional Membership should be addressed to Dr. A. W. Owen,
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Birmingham B4 7ET. Subscriptions cover one calendar year and are due each January; they should be sent to the Membership
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Cover: The chitinozoan Ancyrochitina onniensis Jenkins 1967 from the Late Caradoc, Onnian of the Onny River, Shropshire.
The specimen measures 130 pm in length. Dr. W. A. M. Jenkins provided the photomicrograph.

A REVISION OF S E M I O N O TU S (PISCES:
SEMIONOTIDAE) FROM THE TRIASSIC AND
JURASSIC OF EUROPE

by AMY R. MCCUNE

Abstract. The morphology and taxonomic identity of Semionotus Agassiz, 1832 is clarified, and the
diversity of European species of Semionotus is assessed. Confusion about Semionotus dates back to Agassiz’s
original description in which he based the type species, S. leptocephalus , on a single specimen, and used it to
argue that the Coburg Sandstone was Jurassic, a point necessary to support his concept of the threefold
parallelism in nature. The specimen disappeared shortly thereafter, and subsequent authors, concluding that
Agassiz’s specimen of S. leptocephalus must have been a young Lepidotes , began to recognize S. bergeri as the
type species. Following an extensive search for the missing holotype of S. leptocephalus , study of relevant
Semionotus material in eleven European museums, and examination of Agassiz’s research notes, I argue that
the holotype of Y. leptocephalus must be considered lost; that Agassiz did differentiate Lepidotes and
Semionotus , as evidenced by his working sketches of those two genera; and that, based on newly described
skull material and Agassiz’s sketches, S. bergeri should be retained as the type species (a request to that effect
is now pending with the International Commission on Zoological Nomenclature).

Semionotus can be distinguished from Lepidotes by the number of suborbitals; Semionotus has a single
anamestic suborbital whereas Lepidotes has two or more suborbitals. Of the forty-one species of Semionotus
named from European material, only four can be considered valid, suggesting that European semionotids are
much less diverse than those of North America. The valid European species, S. bergeri , S. kapffi ,
S. normanniae , and .S', minor , are redescribed.

Semionotids are halecostome fishes which retain a suite of primitive actinopterygian features
characteristic of the ’holostean’ level of organization (see Woodward 1895; Schaeffer and Dunkle
1950; Patterson 1973). Members of this family were first described from the Triassic and Jurassic
of Germany during the first third of the nineteenth century (Agassiz 1832; Berger 1832). Since
then, numerous species ranging from Triassic to Cretaceous in age have been named (Woodward
1895). Semionotids have been found in both freshwater and marine sediments, and on all continents
except Antarctica.

In lacustrine sedimentary cycles of the Newark Supergroup in eastern North America, semionotids
are particularly abundant. They apparently dominated many of the lakes that, through time,
repeatedly formed and evaporated in each of a series of rift valley basins. The fossil record left by
their colonizations, extinctions, and speciation is unusually detailed. Most fishes are preserved
whole and articulated in microlaminated sediments that provide us with a very fine-scale (perhaps
yearly) chronology. Excavations of individual sedimentary cycles have yielded many thousands of
specimens representing more than twenty new species of semionotids (McCune et al. 1984) and
large numbers of better-preserved specimens of previously known species.

Before recent excavations it was generally thought that American semionotids were ‘oversplit’
(e.g. Woodward 1895; Schaeffer 1967). While many of the nineteenth-century descriptions are not
diagnostic, recent studies have shown that the North American semionotid fauna is far more
diverse than is apparent from the earlier literature (Olsen et al. 1982; McCune et al. 1984; McCune,
in press a). All semionotids from the Newark have been referred to Semionotus , although Cornet
et al. (1973) noted that at least some Newark semionotids strongly resemble Lepidotes minor from
the Purbeckian of Dorset. Such difficulty in distinguishing Semionotus from Lepidotes dates back

| Palaeontology, Vol. 29, Part 2, 1986, pp. 213-233, pi. 22.|

214

PALAEONTOLOGY, VOLUME 29

to Agassiz’s original description of the type species, S. leptocephalus , in which he pointed out its
strong resemblance to a young Lepidotes (Agassiz 1836).

Those working with American semionotids have not been able to compare them with European
type material because, shortly after Agassiz described the genus, the only existing specimen of the
type species disappeared. Uncertainty about the morphology and taxonomy of Semionotus has
been aggravated further by the incorporation of stratigraphic information into taxonomic
judgements. Agassiz used Semionotus to argue a Jurassic age for the Coburg Sandstone which, had
it been true, would have been consistent with Agassiz’s ideas about the threefold parallelism in
nature (see below). It has long been known, however, that the Coburg Sandstone is Triassic.
Unfortunately the occurrences of Semionotus in the Triassic Coburg Sandstone and Lepidotes in
the Jurassic Posidonienschiefer were generalized by some (e.g. Fraas 1861) to argue that Semionotus
is found only in the Triassic and Lepidotes only in the Jurassic; this erroneous stratigraphic
generalization has sometimes been used to distinguish the two genera.

In order to refer the numerous new semionotids from the Newark Supergroup to a genus it was
necessary to re-examine the morphology and taxonomy of Semionotus. Study of the reference
material in eleven European museums enabled me to examine most European specimens of
Semionotus , including all type and figured specimens of currently valid species, and thus compare
the morphological diversity of the European and North American faunas. I also searched extensively
for the missing holotype of S. leptocephalus. From these studies and a literature review I have
untangled the muddle of taxonomy, morphology, and stratigraphy that surrounds Semionotus ,
redefined the genus, reviewed the valid European species, and judged many other named species to
be invalid.

HISTORY OF SEMIONOTUS

Louis Agassiz (1832), in a letter about his research on fossil fishes to his friend Professor Bronn of the
University of Heidelberg, reported a new kind of ganoid fish from the Lias near Boll, Germany. He later
described this fish, which he named Semionotus (Agassiz 1836, p. 222), and another closely related genus,
Lepidotes (Agassiz 1837, p. 233), in his classic Recherches sur les Poissons Fossiles. The taxonomic and
morphological distinctions between these two genera have always been blurred. Agassiz (1836, p. 226) himself
noted that the type-species of Semionotus , S. leptocephalus , resembled a young Lepidotes. For most workers
since Agassiz (cf. Fraas 1861) the distinction has been stratigraphic only, Semionotus being Triassic and
Lepidotes Jurassic.

Agassiz (1832, 1836) based Semionotus on S. leptocephalus. He could not have been more explicit in his
designation of S. leptocephalus as the type species: ‘L’espece type de ce genre est le Semionotus leptocephalus
du Lias de Boll’ (Agassiz 1836, p. 222). However, his description of S. leptocephalus was based on a single
specimen (text-fig. 1) from the collections of the Agricultural Society of Wurtemberg at Stuttgart which he
had seen in 1831 (Agassiz 1834, pi. 26, fig. 1; 1836, p. 224; 1837, pp. 225-227). By 1861, Fraas was unable to
find the figured specimen in the Society’s collections, and apparently none of the authors who had written on
Semionotus in the meantime had seen this holotype and unique specimen of S. leptocephalus. It is clear that by
1843 the working standard for comparison was S. bergeri (Agassiz 1833, 1834, 1836), not S. leptocephalus
(Berger 1843; Costa 1851; Schauroth 1851; Borneman 1854), and S. bergeri has since been considered
(erroneously) as the type species of Semionotus (cf. Woodward 1895).

Recognition of S. bergeri as the type-species dates back to a suggestion made by Fraas (1861). The
substitution is improper by modern standards, but at the time it seemed common sense. Fraas never explicitly
transferred the name Semionotus from S. leptocephalus to S. bergeri. Rather, he asked the rhetorical question,
‘May the name Semionotus which Agassiz had proposed on the basis of another, Liassic fish [S'. leptocephalus ]
be transferred to the Keuper fish [5. bergeri ]?’ (Fraas 1861, p. 89), and argued that the genus was apocryphal
as it included only one poorly figured missing specimen (Agassiz 1834, pi. 26, fig. I). Almost everyone since
Fraas has adopted S. bergeri as the type species of Semionotus (Struver 1864; Deecke 1889; Woodward 1895;
Schellwein 1901; Schaeffer and Dunkle 1950).

Fraas also suggested that Agassiz’s interest in Semionotus was more than taxonomic, and chided Agassiz
for trying to impose preconceived ideas about the organization of fishes on to the geological record (Fraas
1861, p. 85). Agassiz had described a Liassic fish, S. leptocephalus , which according to Agassiz resembled a

McCUNE: EUROPEAN SEM IONOTUS

215

text-fig. 1 . Semionotus leptocephalus (top) and .S', bergeri (bottom), from Agassiz
(1834, pi. 26). Lithograph by Joseph Dinkel.

216

PALAEONTOLOGY, VOLUME 29

young Lepidotes. This single specimen came from a locality that had produced many Lepidotes. Although
Agassiz himself could not distinguish his specimen from Lepidotes by description or by figure (Agassiz 1834,
pi. 26, fig. 1; 1836, p. 22), he gave it a new name, Semionotus , and included in that genus the fish from the
Coburg Sandstone, S. bergeri. Agassiz then used the similarity of the fish from Coburg ( S . bergeri) to the
Liassic fish (S. leptocephalus) to argue for a Liassic age for the Coburg Sandstone (Agassiz 1837, p. 226),
which was thought to be Keuper then as well as now. As a Liassic fish, Semionotus was evidence for this
threefold parallelism in nature, specifically the parallel between the succession of fossil fishes and the chief
epochs of creation represented by geological periods (Agassiz 1832, p. 143). Fishes with homocercal tails first
appeared in the Jurassic, and Triassic rocks were supposed to be dominated by fishes with heterocercal tails
(Agassiz 1833, p. 3; 1834, pp. v-vi; Fraas 1861, p. 86). Therefore, to Agassiz, it was important to show that
the beds at Coburg which produced fishes intermediate in morphology, with abbreviated heterocercal tails,
were also intermediate in age, that is Liassic.

From the preceding discussion it might seem clear that Agassiz was forcing an issue. S. leptocephalus was
probably Lepidotes, and aside from S. leptocephalus it was reasonable for Fraas and others to associate
Semionotus with the Triassic and Lepidotes with the Jurassic. Although Agassiz’s published figures and
descriptions do not distinguish these two genera convincingly, his working sketches of S. leptocephalus and L.
elvensis (described by Agassiz as L. gigas), now in L’Archiv de L’Etat, Neuchatel (text-fig. 2; Surdez 1973),
show that he saw a significant difference between Semionotus and Lepidotes , though he neglected to mention
the difference in his description. His sketch of Lepidotes illustrates several suborbitals below the circumorbital
series (text-fig. 2b), but in Semionotus he figures only one suborbital (text-fig. 2a). Semionotus is also now
known from throughout the Jurassic (Cornet et al. 1973; Olsen et al. 1982; 5. (= L.) minor, this paper).
Thus, while there are no other reports of Semionotus from the Jurassic Posidonienschiefer, it would not
have been a stratigraphic anomaly to find Semionotus in the Lias near Boll. The rarity of Semionotus at Boll
might even result from a taphonomic bias or a bias of collectors towards beds with more glamorous
fossils like ichthyosaurs, plesiosaurs, or the large fishes. The probability of a collecting bias is increased
by the fact that different taxa are segregated stratigraphically in the Holzmaden quarries (Dr Rupert Wild,
pers. comm.).

The definitive answer to the question, ‘What is SemionotusT can only be supplied by Agassiz’s specimen of
S. leptocephalus , and I have made considerable efforts to relocate it. I have searched the Staatliches Museum
fur Naturkunde Stuttgart (which according to Dr R. Wild has held the collections of the Agricultural Society
of Wurtemberg at Stuttgart since 1864), the Museum National d’Histoire Naturelle in Paris (where Agassiz
was studying when he described S. leptocephalus), the Institut de Geologie de l’Universite de Neuchatel
(which now holds Agassiz’s collection from the Academie de Neuchatel, where he completed Recherches sur
les Poissons Fossiles), and the collections in Tubingen, Munich, Gottingen, and Zurich; I have been informed
by curators of the collections in Coburg, East Berlin, and Frankfurt that they do not have the specimen; I
have examined Agassiz’s research notes and manuscript for Recherches sur les Poissons Fossiles as well as
selected correspondence at l’Archiv de l’Etat in Neuchatel, and the Museum of Comparative Zoology and
the Houghton libraries of Harvard University. All these efforts have been unsuccessful, so it would be
unacceptable to restore S. leptocephalus as the type-species of Semionotus. Yet Semionotus has been so widely
known for so many years that it is desirable to retain the name. Therefore, I have petitioned the International
Commission on Zoological Nomenclature (McCune, in press b) to annul the original type designation of S.
leptocephalus by Agassiz and to designate S. bergeri as the type species of Semionotus under Article 79. Under
the provision of Article 80, common usage is to be continued until a ruling is made, so S. bergeri stands as the
type species.

SYSTEMATIC PALAEONTOLOGY

Abbreviations for repositories. AMNH, American Museum of Natural History, New York; BMNH, British
Museum (Natural History), London; BSM, Bayerische Staatssammlung fur Palaontologie und historische
Geologie, Munich; BGS.GSM, British Geological Survey, Geological Survey Museum, London; IGUN,
Institut de Geologie Universite de Neuchatel; LCUC, Larsonneur Collection, University of Caen; MCZ,
Museum of Comparative Zoology, Harvard University, Cambridge; MGAU, Geologisch-Palaontologischs
Institut und Museum der Georg-August-Universitat, Gottingen; MNHP, Museum National d’Histoire
Naturelle, Paris; RSM, Royal Scottish Museum, Edinburgh; SMNS, Staatliches Museum fur Naturkunde
Stuttgart; ULPS, Universite Louis Pasteur Strasbourg, Institut de Geologie; UT, Institut und Museum fur
Geologie und Palaontologie Universitat Tubingen; YPM, Peabody Museum of Natural History, Yale
University, New Haven.

McCUNE: EUROPEAN SEMIONOTUS

217

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TEXT-FIG. 2. Agassiz’s working sketches of a, Semionotus leptocephalus and b, Lepidotes
elvensis ( = L. gigas Agassiz). Both from l’Archiv d’Etat, Neuchatel, Switzerland.

218

PALAEONTOLOGY, VOLUME 29

Class OSTE1CHTHYES
Subclass ACTINOPTERYGII
Infraclass neopterygii
Order semionotiformes
Family semionotidae Woodward, 1890
Genus semionotus Agassiz, 1832

Type species. S. leptocephalus Agassiz, 1836, by original designation; S. bergeri Agassiz, 1837 (cf. Woodward
1895), by common usage; subsequent designation of S', bergeri as the type-species by the International
Commission on Zoological Nomenclature is pending (McCune, in press b ).

Revised diagnosis. Flalecostome fishes which share the following synapomorphies with Macrosemius
and Lepisosteus: gular and intercalar lost; epiotic with large posteriorly directed process; premaxilla
with long nasal processes; only arch of mesocoracoid ossified in shoulder girdle; first infraorbital
subdivided; ethmoidal ossification reduced to splint (Olsen 1984). Semionotus lacks the synapomor-
phies which define the macrosemiids (Olsen 1984) and lepisosteids (Wiley 1976) and shares with
most Lepidotes a series of simple, convex scales with moderate to well-developed, posteriorly
directed spines along the dorsal midline between the extrascapulars and the origin of the dorsal fin
(see text-fig. 6a). Semionotus has a single anamestic suborbital whereas Lepidotes has two or more
suborbitals.

European species. S. bergeri , S. kapffi , S. normanniae , S. minor. European material formed the basis for
Semionotus and is the focus of this paper. [Semionotus has also been described from many other parts of the
world, although it is the author’s opinion that, here too, there is confusion between Lepidotes and Semionotus ,
and that the validity of many of these other species is doubtful. Therefore, non-European species are not
listed here. Readers interested in non-European semionotids are referred to Woodward (1895) and to the
following selected literature: Africa (Brough 1931); North America (Newberry 1888; Eastman 1905, 1911,
1914; Schaeffer and Dunkle 1950; Schaeffer 1967; Olsen et at. 1982; McCune et al. 1984; McCune, in press a);
South America (Rusconi 1950); Asia (Olsen et al. 1982; Dezao 1983).]

Distribution of European species. Stubenstein, Upper Triassic (Norian) of West Germany; Upper Triassic
(Rhaetic) of France; Upper Jurassic (Purbeckian), Great Britain; Upper Triassic (Rhaetic) of Sweden.

Description. Good skull material of European Semionotus is rare, and I limit my discussion to individual
skulls in the species descriptions that follow (see S. bergeri). Body shape is variable, from fusiform to rather
deep-bodied. There is a single relatively small dorsal fin; its length at the base is approximately 20 % of the
standard length. Pectoral and pelvic fins are ventrally placed; the pelvics are about midway between the
pectorals and the anal fin. The origin of the dorsal fin is slightly posterior to the middle of the back; the anal
fin originates slightly posterior to that. The first lepidotrichium of all fins is preceded by paired basal and
fringing fin fulcra. The body is sheathed by a fabric of interlocking ganoid scales. Scale margins are usually
smooth but may be serrated as in S. normanniae (Larsonneur 1964) or 5. (= L.) minor (Woodward 1916-
1919). The outer layers of the scales are ganoine, the inner layers bone, and there is little or no dentine
(Thomson and McCune 1984). The scale immediately anterior to the anal fin is enlarged, as are the scales
along the dorsal and ventral margins of the caudal peduncle. Teeth are small, simple, and conical.

Discussion. Semionotus is defined here relative to the monophyletic group (Macrosemius + Lepiso-
sfms + the ‘ S . elegans group’) discussed by Olsen (1984) and not the family Semionotidae
Woodward, 1890 because the diagnostic (derived) features of the latter and taxa included in the
family are uncertain. The Semionotidae may include as many as thirteen to twenty-two genera
(Schaeffer and Dunkle 1950; Patterson 1973), and as such is most certainly a grade, there being no
good synapomorphies to demonstrate monophyly of the family. Some have suggested that certain
taxa, such as the dapediids (Wenz 1968), Woodthorpia , and Archaeolepidotus (Lehman 1966),
should be excluded from the Semionotidae. For the Semionotidae to be monophyletic, it is likely
that the family must be even further restricted, perhaps to Lepidotes and Semionotus only (Olsen
and McCune, in prep.).

Semionotus is readily distinguished from Lepidotes by its single suborbital, whereas the latter

McCUNE: EUROPEAN SEMIONOTUS

219

text-fig. 3. Comparison of the skulls of a, Semionotus after Olsen and McCune (in
prep.) and b, Lepidotes after Wenz (1968). Stippled regions are deep relative to the
dermal skull. Note that much of the palate is visible in Semionotus (stippled area)
while the palate is almost completely covered by extra suborbitals in Lepidotes.

has two or more suborbitals in the cheek region (text-fig. 3). A single anamestic suborbital has
been interpreted as a derived trait among primitive actinopterygians (Schaeffer and Dunkle 1950;
Patterson 1973; Wiley 1976); if this is correct, then Semionotus and all Newark semionotids (Olsen
et al. 1982) must be considered monophyletic.

Other characters have been suggested to distinguish Semionotus from Lepidotes , but few of these
hold up to further scrutiny. A median vomer has been described in Lepidotes (Woodward 1916-
1919), whereas the vomer is paired in Semionotus. However, Jain (1983) discovered that fusion of
the vomers in Lepidotes is correlated with size; the vomer is paired in smaller Lepidotes. Jain (1983)
suggested several other characters that may distinguish the two genera, including: 1, preoperculum
inclined forward in Semionotus , but almost vertical in Lepidotes ; 2, Lepidotes has three antorbitals
while Semionotus has one or two; 3, body form less deep in Semionotus than Lepidotes ; 4, dorsal
ridge scales conspicuous and acuminate in Semionotus , inconspicuous in Lepidotes ; and 5, angles of
overlap margin not produced forward as prongs in Semionotus , but produced forward as prongs in
Lepidotes. As discussed below, study of new specimens of Semionotus from Europe and North
America show that the two genera do not differ in these features.

The dorsal ramus of the preoperculum of both S. bergeri (text-figs. 3 and 4) and Lepidotes
appears to be vertically oriented, curving ventrally and anteriorly at about 45° on the dorsal
surface. Preoperculum shape and orientation does seem to vary in both genera but this variation is
probably determined by preservation, especially the relative positions of the suborbitals and the
opercular series.

Jain (1983) suggested that Lepidotes has three antorbitals in contrast to one or two in Semionotus.
While one antorbital and an adjacent infraorbital element lie anterior to the lachrymal ( = two
antorbitals in Jain’s terminology), in S. kanabensis Schaeffer and Dunkle, 1950, and other American
semionotids, the series of infraorbital elements anterior to the lachrymal (the bone joining the
ventral and dorsal elements of the circumorbital series) may number three (Olsen et al. 1982, figs.
11, 12) or even four ( S . micropterus (Newberry), YPM 8605) in others.

Not all Semionotus are more slender than Lepidotes ; S. kapjfi Fraas and a number of American
Semionotus (McCune et al. 1984) are deeper-bodied than Lepidotes.

While the dorsal ridge scales of many Semionotus are conspicuous with well-developed spines,
these scales in other species, such as S. braunii (Newberry), are relatively poorly developed (Olsen
et al. 1982). Furthermore, some Lepidotes , such as L. laevis Agassiz (Saint-Seine 1949), have very
well-developed spines. L. minor Agassiz, which I suggest below should be referred to Semionotus ,
may show dorsal ridges scales both with and without well-developed spines (text-fig. 5). The

220

PALAEONTOLOGY, VOLUME 29

text-fig. 4. Skull of Semionotus bergeri Agassiz, MGAU 1009-5, from the Keuper of Coburg, a,
photograph, medial view, b, camera lucida drawing, medial view. Abbreviations: io, infraorbital; sob,
suborbital; q, quadrate; q j, quadratojugal; pop, preoperculum. Scale bar = 1 cm.

A B

text-fig. 5. Dorsal ridge scales of Semionotus minor (Agassiz), a,
BMNH 41157. b, BMNH 36081. Spines point posteriorly; stippled
area is bone; white is covered by ganoine. Scale bars = 1 cm.

probable primitive condition for dorsal ridge scale morphology in semionotids is convex with
posteriorly directed spines.

Pegs or prongs on the flank scales are characteristic of Semionotus (Schaeffer and Dunkle 1950;
Larsonneur 1964) as well as Lepidotes and therefore cannot be used to differentiate them.

One character that has not been discussed very seriously is size. Most recognize that Lepidotes is
generally large relative to Semionotus , but obviously Lepidotes species are small sometimes, and the
rarity of large Semionotus may be due to preservational or collecting biases. The usual difference in
the size of individuals of these two genera is so great, however, that size may indeed be a useful
character and one that can be tested by compiling length-frequency distributions and analysing
growth rings in the scales (e.g. Thomson and McCune 1984).

Many but not all Lepidotes (e.g. some L. elvensis) have crushing dentition (Woodward 19 lb-
1919; Jain and Robinson 1963; Jain 1983), although this character, like that of fused vomers, could
be related to size. Large Semionotus (which are rare) may be nearly as large as some Lepidotes, but
do not have crushing dentition (McCune, in press a). A possible exception is L. toombsi Jain and
Robinson, which does have crushing dentition like other Lepidotes but, like Semionotus, has only a
single suborbital (BMNH P25180). L. toombsi should perhaps be referred to Semionotus, but I
leave it as Lepidotes until a comprehensive study of character distribution among the species of
these two genera is undertaken.

McCUNE: EUROPEAN SEMIONOTUS

221

Therefore, the characters distinguishing Lepidotes and Semionotus are limited to: 1 , one suborbital
in Semionotus , two or more in Lepidotes ; 2, Lepidotes is generally larger than Semionotus and the
vomers are generally fused in the former; and 3, semionotids with crushing dentition are Lepidotes
(with the possible exception of L. toombsi). Each of the four European species of Semionotus can
be recognized by one or more autapomorphies.

Semionotus bergeri Agassiz, 1 833

Plate 22; text-figs. 4 and 6

1832 Palaeoniscum arenaceum Berger, p. 18, pi. I, fig. 1.

1 833 Semionotus spixi Agassiz, p. 8.

1833-1836 Semionotus bergeri Agassiz, pp. 8 [name, 1833], 224 [descr. 1836], pi. 26, fig. 2 [1834*/].

1843 Semionotus esox Berger, p. 86.

1861 Semionotus elongatus Fraas, p. 95, pi. 1, fig. 4.

Revised diagnosis. Semionotid with only one anamestic suborbital, shape moderately fusiform (see
Table 1); vomers paired; four to six basal fulcra on dorsal fin; four to six fringing fulcra on dorsal
fin; dorsal ridge scales simple, convex, with well-developed posteriorly directed spines; teeth small,
simple, and conical.

Type material. MGAU 489-1, from the late Triassic Coburg Sandstone, Coburg, West Germany, here
designated lectotype, is complete but badly preserved (PI. 22, fig. 4). Paralectotypes are BSM 572 (complete
fish) and a slab of thirteen fish probably at Natur-Museum, Coburg; other Berger specimens mentioned by
Agassiz are unrecognizable in the MGAU Berger collection.

Berger (1832) described ‘ Paleoniscum arenaceum ’ in the same year that Agassiz (1832, p. 145) first named
Semionotus. In this early publication, Agassiz neither described nor figured any species of Semionotus. Later,
in Poissons Fossiles , he named and described S. bergeri (Agassiz 1833), and included Berger’s specimen of P.
arenaceum in that species (Agassiz 1836). Berger's specimen was clearly not Paleoniscum but, as the senior
synonym, arenaceum should have been retained. Agassiz chose not to do so, probably because arenaceum (the
root ‘aren-’ means sand) was meant to indicate the presence of this fish in Keuper sandstone (Fraas 1861), a
possibility that Agassiz wanted to refute.

Although Agassiz clearly designated a type-species for Semionotus , he did not specify a holotype for S.
bergeri. His artist, Joseph Dinkel, figured the Munich specimen for Poissons Fossiles (Agassiz 1834, pi. 26, fig.
2), but Agassiz noted in the accompanying text that Berger’s material was superior. Woodward (1895)
reported that the type of S. bergeri was in Gottingen, but he did not specify a particular specimen by number
or description. Agassiz (1837) mentioned a number of specimens in Berger’s Collection but only the specimen
figured by Berger in 1832 (MGAU 489-1) is recognizable today. There are four other specimens from Berger’s
Collection in Gottingen but they cannot be matched with the brief descriptions given by Agassiz. I was not
permitted to examine the material mentioned by Agassiz at the Natur Museum, Coburg. Thus, the best
candidates for a lectotype are the specimen figured by Agassiz (1834, pi. 26, fig. 2: BSM 572) (PI. 22, fig. 1)
and the specimen figured by Berger (1832, pi. 1, fig- I : MGAU 489-1) (PI. 22, fig. 4). I designate MGAU 489-1
as the lectotype following Berger (1832) and Woodward (1895).

text-fig. 6. Semionotus bergeri Agassiz. Camera lucida drawings of a, dorsal ridge scales
on Gottingen specimen (MGAU 489-1) figured by Berger (1832) and b, dorsal fins of
MGAU 489-1 (right) and BSM 572 (left). Scale bar = 1 cm.

222

PALAEONTOLOGY, VOLUME 29

Other material. BMNH P1547; SMNS 4473, 50972, 51835, and 51841; MGAU 1009-5, 1009-1, 1009-4, 1009-
2; UT, Stoll Collection, which does not include S. kapffi or S. elongatus as Stoll (1929) suggested (the ‘deep-
bodied’ forms are two fish superimposed); BSM 307 (questionable, composite specimen).

Description. S. hergeri is easily recognized by the set of primitive characters given in the diagnosis. However,
it has no characters which are derived within Semionotus. Most of the material is rather badly preserved, and
a number of specimens in various museums have been misidentified. This description is based primarily on
four specimens (BSM 572; MGAU 489-1 and 1009-5; SMNS 51835).

The lectotype (PI. 22, fig. 4) is very poorly preserved, but its overall body shape is clearly fusiform; the
dorsal ridge scales are convex with well-developed, posteriorly directed spines (see also text-fig. 6). The fins
are fringed with fulcra and the body is covered with ganoid scales.

Dermal bones of the skull are easier to interpret in BSM 572 (PI. 22, figs. 2 and 3) than in the lectotype.
The former has only a single suborbital. The pattern of bones emphasized by retouching in Plate 22, fig. 3 is
convincingly Semionotus- like (text-fig. 3a) rather than Lepidotes- like (text-fig. 3b). The ventral dentigerous
portion of the premaxilla, part of its ascending process, the ventral border of the mandible, the preoperculum,
part of the parasphenoid, the interoperculum, the supratemporal, the anterior, dorsal, and posterior borders
of the operculum, part of the cleithrum, and the canal bearing dermopterotic are all visible. There is a
condensation of bone, presumably the quadrate, wedged between the preoperculum and mandible. The cheek
region is notably free of bone. There are other portions of the skull apparently free of bone, such as the
anterior portion of the parietal, the operculum, suboperculum, and the dorsal circumorbitals, but these bones
whose edges are defined by an outline of bone or an impression, were present. Although the suborbital is least
well defined, assignment to Semionotus is confirmed by the facts that there are no Lepidotes known from
Coburg, and that the only good semionotid skull examined from Coburg (MGAU 1009-5; a medial view of
right side of skull; text-fig. 4a) is unquestionably Semionotus. Interpretation of MGAU 1009-5 (text-fig. 4b)
depends on both preserved bone and negative impressions. The single suborbital and an impression of the
quadrate and quadratojugal are obvious. There are clearly no extra suborbitals in the cheek region.

The dorsal fin comprises at least fifteen lepidotrichia, preceded by four to six basal fulcra and at least
four to six fringing fulcra (text-fig. 6b). The first three are basal fulcra; seven more lie against the unsegmented
portion of the first lepidotrichium. In the caudal fin there are about sixteen or seventeen lepidotrichia, about
eight of which compose the lower lobe of the tail. Anal lepidotrichia number seven to ten. See table 1 for
meristic and morphometric data.

Other details of semionotid morphology, especially relevant to relationships of the Semionotidae, are
described by Larsonneur (1964) and below for S. normanniae , by Woodward (1916-1919) for 5. (= L.) minor ,
and by Schaeffer and Dunkle (1950), Olsen et at. (1982), and Olsen and McCune (in prep.) for American
semionotids.

Semionotus kapffi Fraas, 1861

Text-fig. 8

1861 Semionotus kapffi Fraas, p. 95, pi. 1, figs. 1 and 2.

Revised diagnosis. A deep-bodied semionotid; simple convex dorsal ridge scales with well-developed
spines; twenty-one to twenty-three scale rows between posterior edge of cleithrum and origin of

EXPLANATION OF PLATE 22

Figs. 1-4. Semionotus bergeri Agassiz. Late Triassic, Coburg Sandstone, Coburg, West Germany. 1 3, BSM
572, referred to and figured by Agassiz (1834, pi. 26, fig. 2), a paralectotype, showing 1, the complete
specimen, x 0-53; 2, the skull retouched; and 3, the skull unretouched, x 1-3. 4, MGAU 489-1, specimen
described and figured by Berger (1832, p. 18, pi. 1, fig. 1 as Palaeoniscum arenaceum ), lectotype, x 0-54.

PLATE 22

McCUNE, Semionotus

224

PALAEONTOLOGY, VOLUME 29

A B

text-fig. 7. Bivariate plots for Semionotus bergeri Agassiz, S. kapffi Fraas, and S. minor (Agassiz).
a, head length against standard length, b, body depth against standard length.

text-fig. 8. Semionotus kapffi Fraas, lectotype, SMNS 3998, from Fraas (1861, pi. 1, fig. 1 ).

dorsal fin; thirty-two scale rows to base of heterocercal lobe; body length about 2-5 x body depth;
head length (relative to standard length) longer than in S. bergeri (see table 1 ; text-fig. 7).

Type material. SMNS 3998 (Fraas 1861, pi. 1, fig. 1), lectotype here designated, collected by Dr Kapff in 1859
from the Stubenstein (Norian, late Triassic) of Heslack, near Stuttgart, West Germany. SMNS 51836 (Fraas
1861, pi. 1, fig. 2) is a paralectotype.

Other material. BMNH 38654 (three specimens), 38655 (two specimens), 38656, plus numerous specimens
from Stuttgart, Wurtemberg; SMNS 3998, 50972, 51835.

Description. S. kapffi is the most easily recognized species of Semionotus because of its distinctive body shape
(text-fig. 8). It has a relatively longer head (text-fig. 7a) and greater body depth (text-fig. 7b) than S. bergeri.
There are about six long, delicate fin fulcra which lie next to the first principal rays of the dorsal and anal fins.
No specimens are sufficiently well preserved for fin rays or caudal rays to be counted. The best skull material
is not good enough to figure a complete skull but there is nothing inconsistent with other non -Lepidotes
semionotids. See table 1 for meristic and morphometric data.

McCUNE: EUROPEAN SEMIONOTUS

225

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SMNS 51835

226

PALAEONTOLOGY, VOLUME 29

text-fig. 9. Semionotus normanniae Larsonneur. A, left premaxilla and nasal. B, frontals. c,
jaw joint. Scale bars = 1 cm; ang = angular; io = infraorbital; pop = preoperculum; qj =

quadratojugal; qu = quadrate.

Semionotus normanniae Larsonneur, 1964

Text-fig. 9

1964 Semionotus normanniae Larsonneur, p. 115, pis. 1 and 2.

Revised diagnosis. Dorsal ridge scales simple, convex with well-developed spines; nasals robust;
twenty-one lateral line scales anterior to dorsal fin; body fusiform; posterior scale margins serrated
with six to eight teeth on anterior scales and fewer on posterior scales.

Type material. Larsonneur did not designate a single holotype but referred to all of his syntypes as holotypes.
The specimen collected and illustrated by Larsonneur (1964, pi. 1, fig. 8), LCUC unreg., from the Rhaetic
(late Triassic) of Airel de Basse-Normandy, France, is here designated lectotype. None of the type-series is
catalogued, but the most important paralectotypes are figured by Larsonneur (1964).

Description. Although this species was rather thoroughly described by Larsonneur (1964), I can add a few
details. The quantity of S. normanniae specimens is small, but their quality is superb. The bone is preserved in
three dimensions and the matrix can be removed by acetic acid or mechanically. Unfortunately, there are no
complete specimens.

Dermal bones of the skull. The premaxillae have long ascending processes (text-fig. 9a) like Amia , Lepidotes
(Deschaseaux 1943; Patterson 1973), and North American semionotids (Olsen and McCune, in prep.). The
nasals are robust (text-fig. 9a) rather than delicate as in North American forms. They are similarly robust in
Amia , Lepidotes , and to a lesser degree S. (= L.) minor , so I interpret this as the primitive condition for
semionotids. The maxilla is free from the cheek and has a peg-like internal maxillary process (see Larsonneur
1964, pi. 1, fig. 1). There appear to be two infraorbitals anterior to the circumorbital ring. Larsonneur figured
two suborbitals between the preoperculum and circumorbital series, but the more ventral one is clearly the
inetapterygoid of the palate (Larsonneur 1964, pi. 1); thus, like other semionotids except Lepidotes, S.
normanniae has a single anamestic suborbital. The frontals are constricted over the orbit and, like most
Newark semionotids (Olsen and McCune, in prep.), are narrow rather than broad (text-fig. 9b).

Pedate and lower jaw. Further preparation of a specimen pictured by Larsonneur (1964, pi. 1, fig. 6) shows
that the jaw joint (text-fig. 9c) is identical to that of North American semionotids (Olsen and McCune, in
prep.) and to that of L. toomhsi (Patterson 1973). The quadratojugal is a splint-like bone which lies along the
dorsal edge of the preoperculum.

Post-cranial morphology. Although there appear to be twenty-four scale rows between the cleithrum and
dorsal fin (Larsonneur 1964, pi. 2, fig. 1), there are remnants of a dorsal fin at the twenty-first scale row.
There is an obvious joint between that point and the dorsal fin labelled by Larsonneur. The specimen is
probably a composite of two or more specimens, the more obvious dorsal fin being from a different fish. The
number of vertical scale rows anterior to the dorsal fin is therefore twenty-one, and total lateral line scale
count is unreliable. The most posterior fragment does not fit the specimen and, as it has been assembled, the
caudal rays point ventrally not posteriorly. No other specimens are complete enough to count scales or take
body measurements.

McCUNE: EUROPEAN SEMIONOTUS

227

Fins. There are at least eighteen caudal fin rays; seven or eight comprise the ventral lobe of the tail. There
are no reasonably complete anal or pelvic fins, although an isolated pectoral fin shows fifteen rays fringed by
about nineteen fulcra (Larsonneur 1964, pi. 2, fig. 2).

Semionotus minor (Agassiz, 1837)

Text-figs. 5 and 10

1833 1837 Lepidotes minor Agassiz, pp. 9 [name, 1833], 260 [descr. 1837], pi. 34 [1 8346]

1895 Lepidotes minor Agassiz; Woodward, p. 94.

Revised diagnosis. Deep-bodied semionotid with sloping forehead; twenty-one to twenty-four scale
rows anterior to dorsal fin and thirty-eight or thirty-nine scale rows to base of heterocercal lobe; fin
fulcra very robust; dermal bones of skull heavily tuberculated; some anterior flank scales serrated.
Dorsal ridge scales dorsally convex, with prominent spines. Unlike S. bergeri , only central axis of
scale covered by ganoine (text-fig. 5).

Type material. Agassiz’s holotype from the Paris School of Mines (text-fig. 10a) has been lost or destroyed.
(At the end of the Second World War, one side of the Paris School of Mines building was bombed. Some of
the collection was destroyed in the explosion and many of the better specimens remaining were stolen. When
the MNHP assumed the School of Mines Collection in the 1960s, this holotype was not included (Daniel
Goujet and Sylvie Wenz, MNHP, pers. comm.). Although Agassiz (1837, p. 260) stated that he had seen
several particularly good examples in the Geological Society of London (now BGS.GSM), no individual
specimens were discussed.

Among the S. ( = L.) minor at the British Museum (Natural History) there is some variation in body shape,
counts of vertical scale rows, counts and size of dorsal fin fulcra, and degree of serrations on the flank scales
(Woodward 1916-1919, p. 28). However, examination of the specimens shows that this variation in body
shape appears to result from distortion. There are relatively deep-bodied forms and more slender forms, but
in the latter the belly is pushed up so that the pelvic fins originate at the ‘ventral’ margin. It is unclear whether
the variation in scale counts, fin fulcra, and degree of serration on the flank scales is continuous. I designate
here a neotype to avoid confusion over the characteristics of this species, choosing a beautifully preserved
‘deep-bodied’ form which is clearly not distorted: BGS.GSM 27975 (text-fig. 10b) from the Purbeck (Upper
Jurassic) of Swanage, Dorset. No features of this specimen are inconsistent with Agassiz’s original figure
(1834, pi. 34; see text-fig. 10a). Based on analysis of the matrix the neotype is probably from the Herston
Fields Quarry (Hancock) at the Middle Purbeck outcrop (R. W. Sanderson, Petrology Unit, BGS.GSM,
pers. comm.). The specimen is included in a catalogue of 1904, but there is no record of when and how it was
acquired. It is possible, but by no means certain, that it was one of the exemplary specimens in the Geological
Society of London Collection on which Agassiz (1837, p. 260) commented so favourably.

Other material. BMNH P2006, 36081, and many more; BGS.GSM 1 17512, 27974, 41 157; MGAU 369-1 (slab
with seven fish from Volksen-Wealden).

Description. Woodward (1916-1919) thoroughly described and figured S. ( = L.) minor from the Purbeck
beds at Swanage, Dorset. Most of these individuals are rather large (about 20-40 cm). Some smaller
individuals (about 10 cm SL) from the Deistersandstein of northern Germany (Volksen-Purbeck) have also
been referred to 5. (= L.) minor (Branco 1887). See table I for meristic and morphometric data.

Discussion. Earlier, I distinguished Semionotus from Lepidotes by the number of suborbitals:
Semionotus has only one and Lepidotes has more than one. Although Agassiz did not point
specifically to this distinction, I have shown that it is reflected in his sketch of S. leptocephalus and
L. elvensis (= gigas) which are the type species of these two genera. L. minor Agassiz is figured by
Woodward (1916-1919, fig. 14) as having only one suborbital, although earlier Woodward (1895)
figured L. minor as having several suborbitals. Thus, L. minor should be referred to Semionotus , as
I have redefined it. 1 refer L. minor to Semionotus here because its similarity to Semionotus has
been noted in particular with reference to Newark semionotids (Cornet et al. 1973; McDonald
1975). Other species of Lepidotes , such as L. toombsi (BMNH P25180) in which the metapterygoid
or other elements of the palate have been mistaken for dermal cheek plates (Jain and Robinson
1963), should probably also be referred to Semionotus , although this species is somewhat

228

PALAEONTOLOGY, VOLUME 29

text-fig. 10. A, ‘ Lepidotes minor Agassiz, original figure from Agassiz (1834, pi. 34). b, Semionotus
( = L .) minor (Agassiz), BGS.GSM 27975, neotype, from the Purbeckian (late Jurassic) of

Swanage, Dorset.

McCUNE: EUROPEAN SEMIONOTUS

229

problematical as discussed earlier. In contrast, L. mantelli (Woodward 1916-1919), L. elvensis
(Deschaseaux 1943; Wenz 1968), and L. laevi (MHNP 1907-17), to name a few well-known species,
clearly have more than one suborbital covering the cheek region. A re-examination of Lepidotes is
evidently needed, but this is beyond the scope of the present work.

COMMENTS ON OTHER NAMED SPECIES OF SEMIONOTUS ,

INVALID OR DUBIOUS

S. allolepis Deecke, 1889, nomen dubium. Single specimen, whole, but badly preserved. Universite de
Strasbourg, Institut de Geologie. Gres bigarre (Zwischensch). Wasselanne. It is definitely not Semionotus,
and probably a perleidiid. The skull bones are heavily sculptured; the maxilla is long and cleaver-shaped. Fin
fulcra are very delicate. The tail is barely heterocercal, with a notch in the dorsal portion.

S. brodei Newton, 1887, nomen dubium. Upper Keuper, Shrewley, near Nottingham. BMNH P7615 includes
five syntypes. Syntype material includes neither skull material nor a view of dorsal ridge scales, so there is no
evidence that these specimens are even semionotid. Furthermore, the one fin that is preserved (Newton 1887,
fig. 4) does not have the usual semionotid arrangement: rather than a series of paired lepidotrichia,
unsegmented at the base, segmented distally, and fringed with fulcra, the rays are divided into several
segments proximally, like some palaeoniscids.

S. dubius Bellotti, 1857, nomen dubium. Upper Triassic, Perledo, Como. This material, along with that of
several other species of Semionotus described by Bellotti, was supposed to be in the ‘Museo Civico proviente
da Perledo [Milan]’. There is no museum in Perledo today; other material collected by Bellotti was deposited
in the Milan Museum but all specimens collected before the Second World War were destroyed in the bombing
of Milan (Dr. R. Wild, SMNS and Herr Professor Dr Rieber, Institut de Pal., Univ. Zurich, pers. comm ).

S. elongatus Fraas, 1861, nomen dubium. Stubensandstein (Norian), Stuttgart, Heslach. Fraas figured two
specimens ( 1861, pi. 1, figs. 4, 5). It is definitely a semionotid, and not Lepidotes , as shown by the dorsal ridge
scales and single suborbital. Unfortunately, the better specimen (fig. 4) has been lost or destroyed. The
remaining one (fig. 5) is not good enough to distinguish it from S. bergeri. There is another specimen (SMNS
51835) which is a slab of thirteen fish. Many of these are S. kapjfi , though some are small, slender-bodied
forms and more slender than S. bergeri. In addition, while the skull of S. bergeri is rather short and stout, the
slender Stuttgart specimens appear to have longer, more pointed skulls, and the dorsal fin placed more
posteriorly. It might seem that the two should be considered separate species, but the only slender forms
known are small (SL = 7-2 cm) whereas the smallest individual of S. bergeri is much larger (estimated SL =
13-4 cm). It is possible that V. bergeri becomes deeper bodied with increased length and that slight differences
in shape are due to differences in size. Study of a larger number of complete S. bergeri , especially in the
smaller sizes, would resolve this question, but none is currently available.

S. gibbus Seebach, 1866, nomen nudum. This species was named without description or figure. The specimen
label is in the Institute of Geology, University of Gottingen, but the specimen itself is missing.

S. gibbus [gibber error] Bassani, 1896, nomen dubium. The type was supposed to have been in the Milan
Museum before the collection’s destruction during the Second World War.

S. inermis Bellotti, 1857, nomen dubium. Destroyed in the Milan Museum during the Second World War.

S. inornatus Henry, 1876, nomen dubium. As an isolated scale, from Boisset, France, it shows no diagnostic
characters of the family Semionotidae, let alone Semionotus. The denticulations described and figured by
Henry (1876) are probably the result of a broken edge.

Heterolepidotes (S.) joassi Woodward, 1887. Jurassic, Strath Brora, Sutherland, Scotland. RSM 1966.41.3.
These specimens are definitely not Semionotus. There are no visible dorsal ridge scales. The skull, though
perhaps too poorly preserved, does not show the large single suborbital. The internal view of the scales is like
that of Heterolepidotes. Both of these features were figured by Woodward (1887), and he later suggested that
S. joassi might be related to Heterolepidotes (Woodward 1895, p. 314).

S. leptocephalus Agassiz, 1836, nomen dubium. Liassic, near Boll, West Germany. This missing specimen has
been discussed thoroughly in the introductory remarks above.

S. letticus Fraas, 1861. Upper Letten Keuper, Lettenkohle, Hoheneck. Seven specimens in SMNS, all very
poorly preserved. On SMNS 4189 the general form of the body is fusiform and the flank scales have smooth,
not serrated, margins. The skull material is too poorly preserved to see any structure. There are neither fins

230

PALAEONTOLOGY, VOLUME 29

nor dorsal ridge scales on any specimens. Oertle (1927) referred the holotype of this species to Engycolobodus,
but claimed that the assorted syntypes should remain as S. letticus. Clearly, Oertle’s action effectively refers S.
letticus to E. letticus.

S. metcalfi Swinnerton, 1928, nomen dubium. Keuper, near Nottingham, England. The whereabouts of this
specimen is unknown. From Swinnerton’s figure, the skull of the holotype could be a parasemionotid.
However, he mentioned spiny dorsal scales along the dorsal midline, and if that is correct, it is not a
parasemionotid. If the skull is figured incorrectly, and the specimen is Semionotus , there is nothing else in
Swinnerton’s description to distinguish it from S. kapffi.

S. nilsonni Agassiz, 1837, nomen dubium. MCZ 5067, Rhaetic, Schonen, Sweden. It is clearly Semionotus , but
is too distorted and incomplete to be identified to species (other than to say it is not S. normanniae).

S. serratus Fraas, 1861, nomen dubium. Stubensandstein (Norian), Mainhardt Woods near Hutton, Germany.
The holotype is the only known specimen. It is a badly preserved and incomplete fish which includes shoulder
girdle, part of the frontals, and the flank just to and not including the dorsal fin. It is a semionotid, as shown
by a few dorsal ridge scales. There are twenty-one scale rows anterior to the dorsal fin, and the scale margins
are serrated. If the specimen is Semionotus , there would be nothing to distinguish it from S. normanniae.
However, the skull is so poorly preserved that it cannot be identified as either Semionotus or Lepidotes.

S. trotti Bellotti, 1857. Upper Triassic, Perledo, Como. This specimen was destroyed in the Milan Museum
during the Second World War.

NAMED SPECIES OF SEMIONOTUS (OUTSIDE NORTH AMERICA)
PREVIOUSLY REFERRED TO OTHER T AX A

alsaticus Deecke, 1 889
australis Woodward, 1890
basalmi Bellotti, 1857
bellotti Ruppell, 1857
brevis Bellotti, 1 857
carinulatus Costa, 1856
curtulus Costa, 1851

hermesi Bellotti MS, 1873
labordei Priem, 1 924
latus Agassiz, 1837
macropterus Schafhautl, 1851
manseli Egerton, 1872
minutus Egerton, 1 843
pentlandi Egerton, 1843
pustulifer Egerton, 1 843
rhombifer Agassiz, 1837
socialis Berger, 1 843
spinifer Deecke, 1 889
striatus Agassiz, 1837
tenuis Woodward, 1890

tenuiserratus Egerton, MS; from Woodward, 1895

Perledius by Stensio (1921)

Zeuchthiscus by Wade (1940)
Archaeosemionotus by Alessandri (1910)
Allolepidotes by Alessandri (1910)
Heterolepidotes by Alessandri (1910)

Eugnathus brachilepis Bassani ( 1 896)

Colobodus ornatus by Woodward (1895)
Pholidophorus latiusculus by Woodward (1895)
Peltopleurus humilio by Woodward (1895)
Eugnathus hermesi by Alessandri (1910)
Parasemionotus by Piveteau (1929)

Colobodus latus by Alessandri (1910)

Caturus by Woodward (1895)

Lepidotes by Woodward (1895)

Pholidophorus by Woodward (1895)

Colobodus latus by Woodward (1895)
Colobodus latus by Woodward (1895)
Heterolepidotus latus by Woodward (1895)
Dictyopyge by Struver (1864)

Colobodus ornatus by Woodward (1895)
Heterolepidotes by Woodward (1895)
Zeuchthiscus by Wade ( 1940)

Colobodus latus by Woodward (1895)

CONCLUSION

An understanding of the morphology of Semionotus , and therefore its taxonomic identity, has been
hampered by poor preservation of specimens, few in number. In the fourteen European museums
visited or contacted during this study there are almost fewer specimens identifiable as Semionotus
than there are named species of the genus. The better preserved S. normanniae and S. (= L.) minor
were described too late in the history of the genus to have affected earlier revisions. By comparing

McCUNE: EUROPEAN SEMIONOTUS

231

these two species and previously undescribed material of S. bergeri and S. kapffi with Lepidotes , 1
have shown that Semionotus can be distinguished from Lepidotes by its single anamestic suborbital.

Of the forty-one species of Semionotus included in Woodward’s (1895) Catalogue , only two are
justifiable. Since then, Larsonneur (1964) has added one and I suggest that at least one ‘ Lepidotes '
should be considered a fourth — Semionotus (= L.) minor. From this taxonomic revision the
question about the diversity of Semionotus in the European Mesozoic can be answered. In marked
contrast to the American semionotid fauna the European fauna is quite impoverished. This
reassessment of species diversity provides a beginning for future consideration of the geographic
and temporal distributions of a group that is, under some circumstances, remarkably diverse.

Acknowledgements. For access to specimens and for their kind hospitality I thank Drs C. Patterson, P. H.
Greenwood, P. Forey, Ms S. Young, and Ms A. Longbottom (BMNH); Drs S. Wenz, P. Janvier, D. Goujet,
and E. Bulfetaut (MNHP and CNRS, Paris); Dr J.-C. Gall and Ms M. Wolf (University of Louis Pasteur,
Strassbourg); Dr C. Larsonneur and Mr M. Rioult (University of Caen); Dr R. Wild (SMNS); Professor
Chere (University of Neuchatel); Dr O. Rieppel (University of Zurich); Dr P. Wellenhofer (BSM); Dr W.-E.
Reif, Mr J. Troster, and Ms C. Vogt (University of Tubingen); Dr H. Janke (MGAU); Professor P.
Dullemeijer, Drs C. Barel, B. Otten, and M. Stiassney (University of Leiden); Dr S. M. Andrews (RSM); and
Dr I. Cook (BGS.GSM).

Travel funds for this research were granted by the National Geographic Society Committee for Research
and Exploration, the Theodore Roosevelt Memorial Lund, and Sigma Xi. Additional support for preparation
of the manuscript was provided by Hatch Project 183-421. Mr A. Pivorunus made my work much easier by
translating hundreds of pages of nineteenth-century German. The photographs were taken by W. K. Sacco
and the author. I thank Drs P. Olsen, B. Schaeffer, D. Schindel, K. Thomson, and D. Winkler for valuable
discussion and comments on the manuscript.

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deschaseaux, c. 1943. Contribution a l’etude du genre Lepidotes. Annls Paleont. 1943, 3-13.

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saint-seine, p. DE. 1949. Les poissons des calcaires lithographiques de Cerin. Nouv. Archs Mus. Hist. nat.
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schafhautl, K. F. E. 1851. Geognostische Untersuchungen des Sudbayerischen Alpengebirges, xxxvi + 208 pp.,
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schauroth, K. von. 1851. Ueber das vorkommen des Semionotus bergeri im Keuper bei Coburg. Z. dt. geol.
Ges. 3, 405 410.

SCHELLWEIN, E. 1901. Ueber Semionotus Ag. Schr. phys.-dkon. Ges. Konigsberg , 42, 1 -33.
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surdez, M. 1973. Catalogue des Archives de Louis Agassiz. Universite de Neuchatel, Institut de Geologie et
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swinnerton, h. h. 1928. On a new species of Semionotus from the Keuper of Nottingham. Geol. Mag. 65,
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wiley, E. o. 1976. The phylogeny and biogeography of fossil and recent gars (Actinopterygii: Lepisosteidae).
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( Monogrf , 1-148, pis. 1-26.

AMY R. MCCUNE

Section of Ecology and Systematics
Division of Biological Sciences
Cornell University, Ithaca
New York 14853, USA

Typescript received 31 August 1984
Revised typescript 26 June 1985

A NEW GENUS OF INADUNATE CRINOID WITH
UNIQUE STEM MORPHOLOGY FROM THE
ASHGILL OF SWEDEN

by STEPHEN K. DONOVAN

Abstract. Bodacrinus columnus gen. et sp. nov. from the Ashgill Boda Limestone of Sweden is described on
the basis of dissociated stem material only. The column is unusual, being trimeric, and trilobate to sub-
trapezoid in outline. Bodacrinus is presumed to be closely related to the disparid inadunate crinoid Ectenocrinus ,
the only other pelmatozoan known to have had a trimeric stalk. Relative stratigraphic positions indicate that
Ectenocrinus may have been the ancestor of Bodacrinus. The stem of Bodacrinus is functionally adapted to
articulate about an axis which is at 90° to the directions of movement in other bilaterally symmetrical columns
such as those of myelodactylids.

The upper Ordovician rocks of the Siljan district, Dalarna, Sweden (text-fig. 1a) contain an
abundant shelly fauna, principally of pelmatozoan columnals, cystoids, crinoid cups, orthocones,
bivalves, gastropods, bryozoans, brachiopods, ostracods, trilobites, tabulates, and rugose corals.
Echinoderms, particularly their columnals, form the dominant part of this fauna and are very
abundant in the flank beds of the Kullsberg (Caradoc) and younger Boda (Ashgill) Reef Limestones.
Only two species of crinoid cup have so far been described from these rocks; Cornucrinus minis
Regnell, 1948 (both Kullsberg and Boda Limestones) and C. longicornis Regnell, 1948 (Boda
Limestone only). Additionally, Grypocrinus genuinus Strimple, 1963 has tentatively been identified
from the Boda Limestone and seventeen further crinoid species have been identified from cups
(Jobson 1983). Lrom columnal evidence it is estimated that over fifty crinoid species are present in
the Boda Limestone flank beds. So far only two inadunate crinoids from the Boda Limestone have
been identified on the basis of columnals: the iocrinid Ristnacrinus sp. and the myelodactylid
Musicrinus bodae Donovan, 1985. A third inadunate with distinctive columnals is described herein,
from the Boda Limestone in Osmundsberget quarry (text-fig. 1b).

The new species is unusual both in its outline, which varies from trilobate (PI. 23, figs. 1, 3, 6) to
almost trapeziform (PI. 23, fig. 5), and in being trimeric. Meric columnals are limited almost
exclusively to the inadunate crinoids and the rhombiferan superfamily Caryocystitida, apart from
the camerate crinoids Cleiocrinus (Ubaghs 1978, p. T65) and Colpodecrinus (Sprinkle and Kolata
1982), and the flexible (l)Arehaeotaxocrinus (Lewis 1981). Trimeric columns are particularly rare
and unusual, and have hitherto only been reported from the inadunate genus Ectenocrinus
S. A. Miller, although not all members of this taxon have a tripartite stem (Warn and Strimple
1977, p. 89). Even when trimeric columnals are present, the column appears to be holomeric in the
dististele, unlike Bodacrinus. The proxistele of the type species, Ectenocrinus simplex (Hall), is
circular, trimeric, with a central pentagonal lumen and radiating crenularium. This is obviously
quite different from the specimen described herein. Unfortunately the crown of the new species is
unknown but the column and distal attachment are represented by numerous specimens. It is most
probable that these columnals represent a new species closely related to E. simplex but with a stem
that is functionally unusual. Lor these reasons, although the columnals represent a homocrinid
close to Ectenocrinus , they are interpreted as representing a new genus.

Crinoid columnal terminology used in this paper follows Moore et al. (1968), Ubaghs (1978),
and Webster (1974).

[Palaeontology, Vol. 29, Part 2, 1986, pp. 235-242, pi. 23.|

236

PALAEONTOLOGY, VOLUME 29

text-fig. 1. a, generalized geological map of the Siljan district of Dalarna, Sweden. The inset map
shows the position of Siljan. The circular outcrop pattern was produced following meteorite impact
(Thorslund and Auton 1975). b, plan of Osmundsberget quarry, with the position of the Bodacrinus
columnus horizon marked by a star. Dip is to the north-west. Both figures after Jobson (1983, figs. 1,
3, respectively). The Fjacka Shale marks the approximate boundary between the Kullsberg and

Boda Limestones.

SYSTEMATIC PALAEONTOLOGY

Class crinoidea J. S. Miller, 1821
Subclass inadunata Wachsmuth and Springer, 1885
Order disparida Moore and Laudon, 1943
Family homocrinidae Kirk, 1914
Genus bodacrinus gen. nov.

Type species. Bodacrinus columnus sp. nov.

Derivation of generic name. After the Boda Limestone.

Diagnosis. A genus of crinoid based on columnals only. Columnals trimeric, low, trilobate to sub-
trapezoid in outline, with a keyhole-shaped lumen and long, subparallel crenulae on the articular
facet of the outer mere only.

Bodacrinus columnus sp. nov.

Plate 23; text-figs. 2a, 3, 4

Derivation of trivial name. After the Latin columna = column.

Types. Holotype, British Museum (Natural History) specimen BMNH E69536. Thirty-three paratypes.

DONOVAN: NEW ASHGILL CRINOID FROM SWEDEN

237

BMHN E69535, E69537-E69565 (E69547 refers to two columnals, E69564 to three columnals). All are either
dissociated columnals, pluricolumnals, or distal terminations of columns with or without cirri.

Locality and horizon. All specimens are from the upper Ordovician (Harjuan Series; Ashgill in terms of the
British succession) Boda Limestone of Osmundsberget quarry, north of Boda, Siljan district, Dalarna, Sweden
(text-fig. 1b).

Diagnosis. As for the genus.

Description. Columnal outline trilobate (PI. 23, figs. 1, 3), triangular (PI. 23, fig. 6), or sub-trapezoid (PI. 23,
fig. 5). Columnals trimeric, with an uneven but symmetrical development of the meres. A larger 'outer' mere
( sensu Willink 1980; text-fig. 3a) is supported by two smaller, lateral meres. The articulum of the outer mere
bears three to five crenulae which radiate from the lumen towards the circumference of the facet and may be
slightly curved. The articular facet is otherwise unsculptured. The lumen is 'keyhole’-shaped, triangular, with
the ‘outer’ side curved outwards and the two lateral sides curved inwards. Meric sutures correspond to the
lumen angles and are apparent on both the articula and on the latus (PI. 23, fig. 7). Columnals lower than
wide. Latera are planar or slightly convex (PI. 23, figs. 2, 4, 8-10), and unsculptured, except in the distal
termination of the column. The latus may be slightly bevelled adjacent to the articula (PI. 23, figs. 9, 10'). The
column generally appears to be homeomorphic, although some specimens may be heteromorphic based on
slight variations in columnal height (e.g. BMNH E69553, where the order of columnals appears to be 1 1 NN 1 ).
Distally the column tapers (PI. 23, figs. 4, 8), although no actual terminal columnal (presumably conical) is
preserved. Cirrus scars on the latus appear circular with a circular lumen and synostosial articulation (PI. 23,
tig. 2). Cirri circular, wider than high, with planar, unsculptured latera (PI. 23, fig. 4).

Discussion. From this sample of only thirty-four specimens, two are distal attachment structures
and a further pluricolumnal shows a definite taper at one end (PI. 23, fig. 10), presumably related
to the distal column. This apparently high frequency of distal stem fragments suggests that the
complete column of B. columnus was short, perhaps with, say, less than 100 columnals.

Functionally, the stem of Bodacrinus is unlike that of other crinoids with a bilaterally symmetrical
stem such as the myelodactylids, platycrinitids, camptocrinids, and Ristnacrinus. The column of
the myelodactylid Musicrinus , for example (text-fig. 2b), has a synarthrial fulcral ridge corresponding
to the longest axis of the articular facet, which enabled the column to coil in a plane and individual
columnals to rock towards their outer and inner surfaces in a see-saw manner. The unusual
arrangement of the crenularium in Bodacrinus would have prevented such movement (text-fig. 2a)

text-fig. 2. A, articular facets of the ectenocrinid Bodacrinus columnus gen. et sp. nov., with an
articulation of radiating crenulae on the 'outer' mere only, b, the myelodactylid Musicrinus bodae ,
with a single fulcral ridge along the long axis of the columnal. Arrows indicate the directions of

preferred movement.

238

PALAEONTOLOGY, VOLUME 29

and made the stem less flexible. Because of the slightly fanning configuration of the crenulae it is
thought that any movement would have been laterally but with a component of twisting towards
the ‘inner’ surface (although ‘outer’ and ‘inner’ are used to describe different sides of the column,
these terms do not necessarily have the same functional significance in Bodacrinus as they do in
Neocamptocrinus Willink, 1980). The slight bevel of the latus seen adjacent to the articula on the
lateral (and, to a lesser extent, the ‘outer’) surfaces in some specimens (PI. 23, figs. 9, 10) may have
aided stem flexibility, allowing more movement in the regions where this would have been greatest.

Bodacrinus was anchored to the substrate by cirri. Cirrus scars are limited to pluricolumnals
from the (presumed) tapering dististele (PI. 23, figs. 2, 4, 8) and arise on adjacent columnals

outer'

B

KD

inner

thxt-fig. 3. Measurements taken from columnals of Bodacrinus columnus gen. et sp.
nov. a, articular facet, b, latus. LD = lumen ‘diameter’, KD = columnal ‘diameter’,
KH = columnal height, lO = inner to outer, LR = left to right. ‘Left’ and ‘right’
are decided arbitrarily, ‘outer’ and ‘inner’ are used sensu Willink (1980), although
the function of this stem is somewhat different to that of the camptocrinids to which
the latter terms were originally applied.

EXPLANATION OF PLATE 23

Figs. 1-10. Bodacrinus columnus gen. et sp. nov. All SEMs of specimens coated in gold. Figs. 2 10 show
paratypes. Figs. I, 3, 5, 6 orientated with ‘outer’ meres towards top of the page. 1, BMNH E69536,
holotype. Stereo pair of the articular facet, x 30. 2, 8, BMNF1 E69540. Distal termination of the column.
2, lateral view of distal part of pluricolumnal showing cirrus scars, x 42. 8, lateral view of complete
specimen, x 18. 3, BMNH E69535. Stereo pair of the articular facet, x 24. 4, BMNH E69542. Distal
termination of the column retaining some cirral ossicles, x 21 . 5, BMNH E69541. Articular facet with sub-
trapezoid outline, x42. 6, BMNH E69539. Articular facet with triangular outline, x 24. 7, BMNH
E69537. Lateral view of meric suture, x 120. 9, 10, BMNH E69538, pluricolumnal, x21. 9, lateral view.
10, ‘outer’ surface.

PLATE 23

DONOVAN, Bodacrinus columnus gen. et sp. nov

240

PALAEONTOLOGY, VOLUME 29

(cirrinodals). These scars do not show a fixed pattern of distribution (cf. PI. 23, figs. 4, 8). Cirral
ossicles have a synostosial articulation and are round, indicating inflexibility in all directions (Lewis
1980). The longest cirrus preserved (PI. 23, fig. 4) is certainly very rod-like, although this may
merely be an artefact of preservation. Cirri were orientated in a number of directions relative to the
stem, which would favour their insertion into a soft substrate as a tree-like root, anchoring either
an upright or, more probably, a recumbent stem. No specimen of Bodacrinus is known that was
attached to a hard substrate. All have been collected from calcareous mudstones and shales,
although columnals may be present in the associated limestone beds from which the recovery of
fossils is more difficult. It is, therefore, concluded that Bodacrinus was most probably attached with
the tapering dististele inserted directly into soft sediment, in which it was anchored by relatively
few, stiff, rod-like cirri.

text-fig. 4. Graphical analysis of data from type specimens of Bodacrinus colunmus
gen. et sp. nov. a, KDio/KDlr. b, LDio/LDlr. c, KDlr/KH. The reference lines in a
and b have a slope of 1 . Brackets in c group represent variations within heteromorphic
columns. Black squares = 1 columnal, open squares = 2, black circles = 3, open circles

= 4, black triangles = 5.

The ‘inner’ face of columnals is consistently flattened (PI. 23, figs. 1, 3, 5, 6). If the attachment
structure was inserted into the substrate at a low angle to the sediment surface, this flattened
surface may have rested directly on the sediment. In this position the stem would only have been
able to move from side-to-side, and slightly into, the sediment. This may have been an adaptation
which prevented the column being swept back and snapped in strong currents. However, it is
emphasized that this is merely conjecture and we really need to know the form of the crown of
Bodacrinus before a more confident functional analysis can be made.

Graphical analysis of the columnals of B. colunmus is more difficult than for ossicles of a more
regular outline. In consequence of the unusual columnal outline the columnal ‘diameter’ (KD) and
lumen ‘diameter’ (LD) were both measured in two directions, ‘inner’ to ‘outer’ (IO) and ‘left’ to
‘right’ (LR) (text-fig. 3a). Columnal height (KH) was measured in the normal manner (text-fig. 3b).

DONOVAN: NEW ASHGILL CRINOID FROM SWEDEN

241

Both KDio/KDlr and LD,0/LD1R plots (text-fig. 4a, b, respectively) show that these columnals
are generally slightly wider than long. Presumably a very wide column (KDLR KDi0) would be
less flexible than a stem composed of very long ossicles (KDLR <§ KDIO), because the former would
allow only comparatively little movement at its lateral extremities. Therefore, the measured
parameters do not suggest the stem was very flexible. KH is generally low (text-fig. 4c), increasing
slightly with increase in KDLR.

The genus Ectenocrinus has a stratigraphic range from the Kirkfieldian or Shermanian to the
Richmondian (Warn and Strimple 1977), i.e. approximately mid-Caradoc to Rawtheyan in terms
of the British sequence (Ross et al. 1982). The stratigraphic position of Bodacrinus approximates to
the upper limit of the range of Ectenocrinus , from which it is assumed to have evolved. This is one
of the first records of an ectenocrinid in Europe, although the author has found rare trimeric
columnals in the Ashgill of Ireland and north Wales. Also, Jobson (1983, p. 28) has recorded an
Ectenocrinus-Uke cup from the Boda Limestone, although this is considerably smaller than most
columnals of Bodacrinus.

Acknowledgements. I thank Clive Auton (BGS, Keyworth), Linda Jobson (Heriot-Watt), and Chris Paul
(Liverpool) for providing specimens and relevant stratigraphic data. Linda Jobson kindly gave permission for
text-fig. 1 to be reproduced from her M.Sc. thesis and for the use of hitherto unpublished information.
Information concerning Ectenocrinus was provided by Bob Titus (Hartwick College, Oneonta, New York).
This paper was improved following constructive criticism by Andrew Smith (BMNH) and Chris Paul.
Research was undertaken during the tenure of a Royal Society European Science Exchange fellowship at
Trinity College, Dublin, which the author gratefully acknowledges.

REFERENCES

donovan, s. k. 1985. Ristnacrinus and the earliest myelodactylid from the Ashgillian Boda Limestone of
Sweden. Geol. Foren. Stockholm Fork. 106, 347-356.

jobson, l. M. 1983. ‘Crinoids and coronoids from the Ordovician of Sweden’. M.Sc. thesis (unpublished).
University of Liverpool.

kirk, E. 1914. Notes on the fossil crinoid genus Homocrinus Hall. Proc. U.S. natn. Mus. 46, 473-483.
lewis, r. d. 1980. Taphonomy, 27-39. In broadhead, t. w. and waters, j. a. (eds.). Echinoderms: notes for a
short course. University of Tennessee, Atlanta.

— 1981. Archaeotaxocrinus , new genus, the earliest known flexible crinoid (Whiterockian) and its
phylogenetic implications. J. Paleont. 55, 227-238.

miller, J. s. 1821 A natural history of the Crinoidea or lily-shaped animals , with observation on the genera
Asteria , Eurayle , Comatula , and Marsupites. Bryan and Co., Bristol.
moore, r. c., jeffords, r. m. and miller, t. h. 1968. Morphological features of crinoid columns. Paleont.
Contr. Univ. Kans., Echinodermata Art. 8, 1-30.

— and laudon, l. r. 1943. Evolution and classification of Palaeozoic crinoids. Spec. Pap. Geol. Soc. Am.
46, 1-153.

regnell, g. 1948. Swedish Hybocrinida (Crinoidea Inadunata Disparata; Ordovician Lower Silurian). K.
Svenska VetensAkad ., Ark. Zool. 40A, 1-27.

ROSS, J. R., jr. et al. 1982. The Ordovician System in the United States. Int. Un. geol. Sci. Pub. 12, I -73.
sprinkle, j. and kolata, d. r. 1982. ‘Rhomb-bearing’ camerate. In sprinkle, j. (ed.). Echinoderm faunas
from the Bromide Formation (Middle Ordovician) of Oklahoma. Paleont. Contr. Univ. Kans., Monogr. I,
206-211.

strimple, H. L. 1963. Dasciocrinus in Oklahoma. Ok/a. Geol. Notes, 23, 101-107.

thorslund, p. and auton, c. 1975. Evidence of meteorite impact in the Siljan structure. Central Sweden.
Bull. Geol. Inst. Univ. Uppsala, N.s. 6, 69-72.

ubaghs, g. 1978. Skeletal morphology of fossil crinoids. In moore, r. c. and teichert, c. (eds.). Treatise on
invertebrate paleontology, part T, Echinodermata 2(1), T58-T216. Geological Society of America and
University of Kansas Press, Boulder, Colorado and Lawrence, Kansas.
wachsmuth, c. and springer, f. 1885. Revision of the Palaeocrinoidea, part II, section 1. Discussion of the
classification and relations of the brachiate crinoids, and conclusion of the generic descriptions. Proc. Acad,
nat. Sci. Philad. 225-364.

242

PALAEONTOLOGY. VOLUME 29

warn, j. and strimple, h. l. 1977. The disparid inadunate superfamilies Homocrinacea and Cincinnaticrinacea
(Echinodermata: Crinoidea), Ordovician-Silurian, North America. Bull. Am. Pcileont. 72, (296), 1-138.
webster, G. d. 1974, Crinoid pluricolumnal noditaxis patterns. J. Pcileont. 48, 1283 1288.
willink, r. j. 1980. A new coiled-stem camerate crinoid for the Permian of eastern Australia. Ibid. 54, 15-34.

STEPHEN K. DONOVAN

Department of Geology
University of the West Indies

Typescript received 21 November 1984 Mona Kingston 7

Revised typescript received 14 March 1985 Jamaica

COMMUNITY PRESERVATION IN RECENT
SHELL-GRAVELS, ENGLISH CHANNEL

by RICHARD CARTHEW and DAN BOSENCE

Abstract. Live and dead benthic faunas have been sampled offshore from Plymouth to assess the relationship
between dead shell accumulations and living benthic communities. The live fauna (354 samples) has been
sampled at approximately twenty-year intervals since 1895. The dead fauna (25 samples) was collected in one
survey in 1980-1981. The live and dead mollusc and echinoderm (185 taxa) abundances are compared using
multivariate statistical analysis (Detrended Correspondence Analysis).

Three distinct communities are defined by this analysis, inhabiting shell-gravel, sand, and mud substrates.
Historic records of the shell-gravel community indicate population fluctuations, and present-day faunas are
most similar to those recorded in the 1920s. The dead shell-gravel fauna is similar to the ‘time-averaged’ live
fauna and distinct from the sand and mud communities. When bivalves alone are analysed then relative
abundances are preserved in dead samples even though these show greater abundance, diversity, homogeneity,
and equitability. The results give support to the interpretation of original time-averaged community structure
from similar fossil shell beds. However, fluctuations in population structure are not preserved because of the
slow sedimentation rates.

One of the fundamental, but still unsolved, problems in palaeocology concerns the nature of the
relationship between preserved fossil assemblages and their original benthic communities. Most
authors consider that the best way to study this relationship has been the investigation of live
communities and their accumulating preservable remains. Many papers have been published during
the last twenty years using this approach. The majority of workers obtained their data from a
single sampling programme of both live and dead shelly faunas. The difficulties of sampling
offshore soft-bottoms have probably contributed to the concentration of many studies from inshore
regions. Thus Peterson (1976) and Warme (1969) studied shallow lagoons off the Californian coast;
Johnson (1965), Cadee (1968), Evans (1968), McCall and Tevesz (1983) studied enclosed bays or
estuaries; Van Straaten (1960), Habe (1956), MacDonald (1969a, b ), Wilson (1967), and Antia
(1977) investigated inter-tidal flats; Bosence (1979a, b) studied a shallow open-bay environment.
The geologically important shelf environment has not received so much attention and only
Hertweck (1972) and Wilson (1982) have ventured into deeper shelf waters.

The consensus of this research is that there is a general correspondence between the communities
and death assemblages but that the structure of the original community is lost because of a
number of processes operating on the accumulating dead material. Post-mortem transportation is
emphasized by Cadee (1968), Bosence (1979a, b), Wilson (1982), and Farrow et al. (1984). Post-
mortem dissolution is considered important by Peterson (1976) and McCall and Tevesz (1983), but
these authors were probably dealing with undersaturated sea water; it has not been considered
important in open marine waters supersaturated with respect to calcium carbonate (Alexandersson
1979; Bosence 1979a; Wilson 1982). Fragmentation during predation can also effect the taxonomic
composition of the dead assemblage (Cadee 1968; Bishop 1975; Farrow and Clokie 1979). Changing
environments and local habitats also cause important differences between the results of surveys of
live and dead material (Bosence 1979a; Powell et al. 1982). The latter authors stress the importance
of this in establishing community composition prior to present-day sampling. The major sources of
differences between Recent live and dead populations is, however, the short-term fluctuations and
patchy distributions characteristic of live benthic communities (McCall and Tevesz 1983). Because
of the high variability of Recent communities, a single sampling will, at its best, only represent the

I Palaeontology, Vol. 29, Part 2, 1986, pp. 243-268.]

244

PALAEONTOLOGY, VOLUME 29

text-fig. 1 . A, sea floor topography, substrate composition below 20 m, and direction of sand transport
(arrows); redrawn from Fleming and Stride (1967). b, localities and dates of the surveys (not publications) in
the western English Channel. Where the surveys overlap, the more recent survey overlies the older.

CARTHEW AND BOSENCE: RECENT SHELL-GRAVELS

245

nature of that community at that instant of time. The occurrences of individual taxa will depend
on such factors as the last successful spatfall, local predation levels, the successional state of the
community following local disturbance, and other biotic interactions or changes in the substrate.
Such short-term fluctuations in soft substrate communities have been reviewed by Gray (1977)
who concludes that the community has an internal stability or resilience whereby temporarily
disturbed communities will return to an earlier organization if the perturbation is removed. Gray
(1977) quotes several cases of temporary dominance changes following perturbations.

Because of the fluctuations in live communities, accumulating death assemblages have been
referred to as ‘time-averaged’ by Walker and Bambach (1971). The dead material accumulating
over a period of time can be considered to average these short-term fluctuations in live populutions.
This aspect of community preservation is also discussed by Warme et al. (1976) and Fiirsich (1978)
who also introduces the term ‘faunal-condensation’ which occurs when sedimentation rates are
slow compared with community production rates. One result of lime-averaging and faunal
condensation is that it is most unlikely that short-term variations such as ecological succession
(autogenic) or the effects of predator-prey fluctuations will be preserved in soft-bottom substrates
(McCall and Tevesz 1983; Paine 1983). McCall and Tevesz (1983) suggest that the preservation of
succession is most unlikely with average shelf sedimentation rates and from a critical review of the
literature suggest that only two examples are known to date. These are the studies described by
Walker and Parker (1976) and Johnson (1977).

Another major effect of these fluctuations is that we should not expect to find a good
correspondence between the results of one sampling programme of the living community and the
associated accumulating death assemblage. Correspondence could only be expected with relatively
stable communities and high sedimentation rates. In most geological examples the fossil assemblage
might be expected to be more similar to the long-term (tens or hundreds of years) community
composition.

This paper presents the results of a comparison of long-term, live faunal sampling with the
present-day death assemblage from an offshore environment (text-fig. 1a). The benthic communities
of the English Channel have been studied by scientists from the Marine Biological Association’s
Plymouth Laboratory at various periods over nearly one hundred years. The results of these
surveys present a unique opportunity to investigate the longer-term community structure and its
relationship to the accumulating death assemblage.

Systematic sampling of the benthic communities of the western Channel was started in the 1890s
by Allen (1899) who covered grounds extending from the Eddystone to Start Point (text-figs. 1b,
2a). Crawshay (1912) sampled a strip south of the Eddystone to the centre of the Channel. Ford
(1923) extended Petersen’s (1914) classic study on benthic communities from the Danish waters
to the English Channel. He included the Plymouth Sound and Eddystone shell-gravels together
with other areas to the south of Plymouth (text-figs. 1b, 2a, b). Smith (1932) carried out a detailed
survey of the Eddystone shell-gravels. Holme (1953, 1961, 1966) has carried out extensive surveys
of the fauna of the western Channel which also include the Eddystone shell-gravels. Finally,
Probert (1973) sampled areas mainly to the west of Plymouth but included Bigbury Bay, an area
previously sampled by Ford (1923). Therefore, the previous work (summarized in text-fig. 1b)
covers four previous samplings of the shell-gravels around Eddystone and one from the Plymouth
Sound shell-gravels. Sampling to update these records for this project was carried out during
September 1980 to May 1981 and included the live fauna together with the dead fauna of three
shell-gravel sites: The Eddystone, Plymouth Sound, and Stoke Point (text-fig. 2). The previous
surveys of the surrounding, mainly finer-grained sea bed provides a useful comparison and have
all been included in the analysis. The total data come from some 379 samples, the majority of
which were investigated by many replicate samples. A multivariate analytical technique was used
to study the variation within these data, to compare live and dead faunas within surveys, and to
compare the present-day dead fauna with previous live surveys and previous surveys of the live
fauna with each other.

246

PALAEONTOLOGY, VOLUME 29

text-fig. 2. Locations of sample stations of earlier workers and those sampled for this
study, a, Eddystone. b, Plymouth Sound, c. Stoke Point. (See Appendix 2 for details of

sample positions.)

THE SHELL-GRAVELS AND THEIR FAUNA

Shell-gravels

Unfortunately there has been little detailed sedimentological work undertaken in the Plymouth-
Eddystone area. Apart from the qualitative and some quantitative (Holme 1953) descriptions in
the biological surveys, the only account of these sediments is by Fleming and Stride (1967).

The Recent sediments comprise sand and gravel patches to the west and a sand sheet to the east
(text-fig. 1a). The sediments are deposited on either the rock floor, as at Eddystone, or on a
terrigenous conglomerate presumed to be a deposit of the post-glacial transgression. Sand patches
are up to 10 cm thick and formed of well-sorted medium- to coarse-grained terrigenous sand. They

CARTHEW AND BOSENCE: RECENT SHELL-GRAVELS

247

are rippled by tidal currents and can be seen to overlie the gravel patches. Gravel patches are
composed of a fine gravel (median diameter 2-6 mm), dominantly of terrigenous origin. Shell sand
may, however, make up 40% of the fine sand grade. Gravel patches are rippled by winter storms
and are up to 25 cm thick. The sand sheet to the east (text-fig. 1a) is being transported westwards
and is composed of a fine sand. Sand waves are found to the south of Bolt Head which pass
westwards into ‘uniform deposits’ towards Eddystone (Fleming and Stride 1967). Boillot (1965)
describes the terrigenous and bioclastic sediments south of this area.

The shell-gravels of this study occur within the sand and gravel patches. The Eddystone gravels
occur around 60 m deep rock outcrops which extend to the surface at Eddystone Rocks. Smith
(1932) records three types of gravel arranged concentrically around the Rocks. The ‘inner gravel’ is
characterized by locally derived gneiss pebbles and shell debris. The ‘middle gravel’ contains little
terrigenous material and is rich in broken and unbroken shells. The ‘outer gravel’ contains
sandstone pebbles and broken shells. In general, the grain sizes of both the total and the shelly
component decrease away from the rocks. Our samples (text-fig. 2) are from the inner and outer
shell-gravels (60-64 m) at stations previously sampled by Allen (1899) and Smith (1932). The shell-
gravels of Plymouth Sound at Queens and New Ground (Ford 1923) and occur at depths of
13-16 m. The Stoke Point gravels occur off a rocky shore at intermediate depths of between
32 and 43 m (text-fig. 2; Appendix II).

Although the processes leading to shell-gravel formation at these three sites are not understood,
they are all affected by strong currents generated by south-westerly storms. Even though the
Plymouth Sound stations are in an enclosed area they are open to the south-west. The Eddystone
gravels would be expected to experience higher currents than surrounding sandy areas of the sea-
floor because of shallowing and wave refraction. Data in Draper ( 1 967) and Channon and Hamilton
(1976) suggests that medium sand-sized quartz sediment could be expected to be transported on
nearly 100 days during the year at depths of 60 m in the western Channel. In the absence of further
information, it seems likely that the gravels occur in sites of low terrigenous supply and/or
winnowing of finer-grained sediment.

Wilson (1982) proposes a model for shell-gravel formation which, with the presently limited
information available, can be applied to the shell-gravels discussed here. He suggests that with
transgression and limited terrigenous sediment supply, sands are swept into patches or sheets over
the basal conglomerate. With no further terrigenous supply carbonate grains are generated from
epifauna on exposed boulders and rock outcrops and the sand sheets are only added to by infaunal
production from the sands. With time, biogenic production increases the grain size of the sand to
a shelly-gravel. The shelly-gravels as they coarsen become less favourable to burrowing by their
original fauna and they are replaced by those taxa which tolerate the coarser sediments. In addition,
production from nearby rocky outcrops may contribute carbonate grains. Periods of increased
current strength would tend to winnow out the smaller clastic grains thus contributing to the
increase in grain size. The increased grain size will also make the gravels more resistent to erosion
and the largest grains may in turn support their own calcareous epifauna.

Fauna

The shell-gravels have a characteristic fauna which is dominated by robust-shelled suspension
feeding bivalves: Venus fasciata, V. ovata , V. casina , Glycymeris glycymeris , Venerupis rhomboides ,
Gouldia minima, Arcopagia crassa, Tellina pygmea, Gari tellinella, and Spisula solida. Smaller
common bivalves are Astarte triangularis (living within the gravel interstices), Montacuta ferruginose
(symbiotic with Spatangus purpuratus), and the deposit feeding Nucula hanleyi. The infaunal
echinoids Spatangus purpuratus and Echinocyamus pusillus are also common as are the polychaetes
Polygordius lacteus and Glycera lapidum. Other characteristic but soft-bodied organisms are the
infaunal cephalochordate Amphioxus lanceolatus and the amphipod Ampeliscina tvpica. Therefore
the community has a very high proportion of preservable taxa. The taxa considered in this paper
from the analyses of past and present surveys are the macrofauna from the Bivalvia, Gastropoda,
and Echinodermata.

248

PALAEONTOLOGY, VOLUME 29

METHODS

Sampling

Most authors used different sampling techniques (Table 1) which has resulted in variable quality of
data for analysis of the historic faunal records. Ford (1923) and Holme (1953) used grabs which,
while producing reasonably quantitative data on fine substrates, have problems caused by incomplete
closure and ‘washing through’ in coarse shell-gravels. In addition, with sparsely distributed or
patchy faunas many samples are required to obtain representative numbers of even the commonest
taxa. The two authors used grabs of different design which would be expected to behave differently
on similar substrates (see discussion in Holme and McIntyre 1984). Other workers used dredges
(Table 1) which, while being easier and quicker to operate, may cover a large and unknown area of
the sea bed. Some dredges (i.e. Anchor and Modified Naturalist’s) bite into the sea bed whilst
others (Naturalist’s) as well as Otter and Beam Trawls do not bite so deep and may travel some
distance over the sea bed sampling different populations. For this survey, sampling was carried out
from the Marine Biological Association, Plymouth, using small vessels and a Naturalist’s dredge
modified with a curved metal frame allowing it to bite into the sea bed. At each station (sampled at
slack water) the dredge was dropped with 2-3 times the warp required for known water depth. The
boat was moved gently until the warp was taut and following a few rapid turns of the engine the
dredge was fast on the sea bed. After retrieval the boat returned to the station for a replicate haul
in the same direction. Initially a 10 1 sample was taken from the centre of the 2 mm dredge bag and
the live and dead fauna counted. Because of the time involved in sorting and counting the faunas
(some taxa occur over a thousand times in one sample) subsamples were taken. No new species
were being recruited after 3 1 of sediment for the live fauna and 2 1 of sediment for the dead fauna
and these volumes of sediment were therefore chosen for sorting. The counts of occurrences of
individuals and species per sample for our stations and those of previous authors are obtainable as
computer listings deposited with the British Library, Boston Spa, Yorkshire, UK, Supplementary
Publication No. SUP14026. The data matrix comprises a total of 185 taxa occurring at 379 samples.
A species occurrence list and species authors’ are given in Appendix 1 .

The live fauna was surveyed in November 1980 and in January, March, and May 1981 to
compare seasonal variations. At least two replicate samplings of the dead fauna were taken from
each station.

Four of Allen’s (1899) stations were relocated on the south-west British Chain Decca from
Allen’s bearings (corrected for magnetic deviation) and distances from the Eddystone Light
(Appendix 2). Four of Ford’s (1923) stations were relocated using Ford’s transits or sightings
(Appendix 2) and three new stations of shell-gravel from Stoke Point were sampled. Allen’s (1899)
samples are, unfortunately, recorded in ‘grounds’. These include all samples that appeared to form
a coherent group as determined by species composition, substrate, and geographic position. Each
‘ground’ is published as one sample with species listed in a semi-quantitative fashion. The original
data have since been lost (Holme, pers. comm. 1982). Ford (1923) published details of 64 samples
but 70 other samples from the same areas were not published as they were not comparable for
sampling reasons (in lift. Ford 1953). These 70 extra samples can, however, be compared on a
semi-quantitative or presence/absence level (Table 2).

Identification

Almost all taxa have been identified to species level. An exception to this is Nucula , for which all
authors have only recorded one species, but each of the pre-1953 identifications is of different
species. It is most unlikely that species occurrence would go by survey and therefore all have been
grouped as Nucula sp. Similarly, all species of Anomia have been grouped because of the difficulty
of identifying dead separated valves. Trivia is now considered as two species, where formerly it was
one, and the prior case is adhered to. The two genera of synaptids (Holothuria) are treated as one
taxon. When dealing with the earlier faunal records many of the taxa have undergone revision and
in all cases we follow the Plymouth Marine Fauna (Marine Biological Association 1957). For this

CARTHEW AND BOSENCE: RECENT SHELL-GRAVELS

249

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PALAEONTOLOGY, VOLUME 29

table 2. Table indicating the different methods of recording faunal occurrences used by different
authors in their published data. Thus Ford (1923), Smith (1932) . . . etc. in column 1 published
quantitative data. Allen (1899) and Holme (1966) recorded their data as listed in columns 2 and 3.
To compare results from the surveys in columns 1-3 the data were transformed to quantitative
(column 4), semi-quantitative (5), or qualitative (6) states.

Published (original) date

Transformed data

1

2

3

4

5

6

Quantitative Abundance
is published by the

Allen (1899), some of

Holme II

underlisted authors

Crawshay’s (1912)

(1966)

Quantitative

Semi-quantitative

Qualitative

Ford (1923)

0

0

0

0

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Smith (1932)

1

1-2

1

1

Holme I (1953)

few

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5

2

Holme II (1961)

numerous

10-99

55

3

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Probert ( 1973)

abundant

100

550

4

This survey

—

—

5500

5

study each species has been assigned a number which is in the order that species appear in the
Plymouth Marine Fauna (see Appendix 1).

Statistical analysis

Because of the size of the data (185 taxa and 379 samples) and the many different ways in which
comparisons are to be made, multivariate statistical analysis was considered essential. Several
multivariate methods are now in common usage in the analysis of species/samples matrices
including Principal Components Analysis, Polar Coordination, Correspondence Analysis, and
Detrended Correspondence Analysis. All of these methods display results as eigenvalue plots
whereby species with the most similar occurrences or samples with the most similar species plot
close together. The most dissimilar species and samples, in contrast, plot far apart. The relative
merits of these methods have been discussed by Gauch et at. (1977), Gauch (1982), Hill (1973,
1974), Hill and Gauch (1980), and Orloci (1978). They are also compared with examples by Spicer
and Hill (1979) and Spicer (1981). The latter authors consider Correspondence Analysis (Hill 1973)
to be most suitable for species/sample data as plots of these are complementary. A brief non-
mathematical explanation of the technique is given in Hill (1973) and Spicer and Hill (1979).
Detrended Correspondence Analysis (DECORANA: Hill 1979) is an improved version of Corre-
spondence Analysis.

The program gives eigenvalues for the first four axes and the number of iterations required to
reach stability. The eigenvalue gives the amount of variance on each axis up to a maximum of 1-00
on each axis. In practice it was found that most of the variance was accounted for on the first two
axes and little further information could be observed from plotting the third or fourth. In Probert’s
(1973) data, all the variance was confined to the first two axes. Sample scores have been zeroed.
Because the sample scores are the mean scores of the species that occur in them, the species scores
will have a broader range and there will always be scores below zero for species (Hill 1979). All
default options in the program were used except when sample data were transformed.

This technique proved robust and the program simple to run. Some samples had to be removed
because they showed so much variation that all other samples clustered together. For example,
sample 339 contained just five Ensis siliqua , a species found only at four out of the remaining 378
stations. The program allows entry of quantitative data, which, once entered, can be transformed
to semi-quantitative or presence/absence form (Table 2) prior to analysis. The quantitative state
was only used in an analysis of our data and those of Ford (1923). A semi-quantitative
transformation (Table 2) was used for the majority of analyses. The intermediate abundances were

CARTHEW AND BOSENCE: RECENT SHELL-GRAVELS

251

calculated linearly between the desired semi-quantitative scores (e.g. 10-21). Abundances greater
than 5500 (only found in the ‘dead’ data) were all transformed to 5. The DECORANA program
was entered and run on the CDC computer at Imperial College, London.

COMMUNITY COMPOSITION AND DISTRIBUTION

Our data have been analysed in a number of ways to study the relationships between the live and
dead faunas of the shell-gravels. First, the entire past and Recent live and dead species occurrences
have been compared semi-quantitatively (text-figs. 3 and 4a). Information from this analysis
compared the shell-gravel community with those from the surrounding sea-floor and the dead
fauna from the shell-gravels. Secondly, the occurrences of bivalves have been analysed as they
represent the dominant components of both the live and dead faunas (text-figs. 4b, c, 5, 6). Thirdly,
our live and dead faunas from the shell-gravels were analysed quantitatively to study in detail the
live fauna and its relation to today’s dead fauna (text-fig. 7).

i

6 00

5 OO

4 00

300

2 00

100

0

0 100 200 300 400 5 00

C

2

text-fig. 3. Contoured distribution of samples. The position
of sample plots is based on their contained fauna so that
samples with similar faunas plot close together and samples
with dissimilar faunas plot far apart. The first and second
axes shown are derived from the Detrended Correspondence
Analysis program. Scale in ‘standard deviations’ (s.d. ). The
distribution of samples, initially plotted as points, has been
contoured on a grid of 0-2 s.d. spacing, so that density is the
number of samples falling within a circle of 0-2 s.d. radius
centred on each grid intersection. The three diagrams show
the distribution when all samples (live and dead), bivalve,
gastropod, and echinoderm data are represented in different
ways, and can thus be regarded as ‘overlays’, a, density
distribution of live samples compared with dead samples; first
contour at one sample per intersection, the next at 5 samples,
and then at increments of 5 samples, b, distribution contoured
by survey; text-fig. 1 and Table I gives dates of each survey.
The contour is drawn at 2 samples per intersection; this omits
some of the outlying, single points, c, distribution contoured
by substrate. Contour at 2 samples per intersection.

252

PALAEONTOLOGY, VOLUME 29

Live and dead faunas from shell-gravels and surrounding areas

A semi-quantitative analysis (Table 2) of the fauna from all the surveys together with our dead
material is illustrated in text-figure 3. Three main clusters are visible separating out on the first
axis. The central cluster, containing samples with intermediate ordinations, is the densest, whilst
samples with higher ordinations on axis 1 cluster with considerable variation along the second axis.
Because the position of each sample plot is based on the species it contains, neighbouring plots of
samples and clusters of samples have similar faunas. Therefore, separate clusters indicate groups of
stations with similar faunal associations. The location of samples and the occurrence of clusters
can be discussed with respect to the possible causes of clustering such as a faunal change through
time, substrate differences, water depth, etc. A simple, graphical way of comparing the importance
of these various controls is by constructing overlays which contour author’s samples (text-fig. 3b),
substrate types or depths (text-fig. 3c). The contouring of samples by author/time (text-fig. 3b)
indicates that no single sampling programme coincides with one cluster. The uppermost cluster
comprises samples from Ford (1923), Holme (1961, 1966), and Probert (1973). The lowest cluster
contains stations of Allen (1899), Crawshay (1912), and Holme (1961, 1966). The central cluster con-
tains samples collected by Allen (1899), Ford (1923), Smith (1932), Holme (1961, 1966), and our
live faunas from the shell-gravels. In addition, this central cluster contains our samples based on
dead shell-gravel faunas which plot in a restricted area within this cluster. This indicates that
similar faunas have been retrieved by different authors, sampling at different periods of time. Also,
it indicates that our dead fauna is similar to live faunas sampled over the last ninety years. This
contouring also allows us to see that the different sampling techniques and recording, together with
our transformation of these data, are not responsible for the clustering of stations (but see Allen
(1899) and Crawshay (1912) below). The central cluster, for example, contains samples from a
range of dredges, grabs, semi-quantitative, and quantitative recording of data (Table 1).

The important effect of substrates on faunal occurrences has been studied by indicating the
sediments recorded at each station (text-fig. 3c). As various authors have used different quantitative
or descriptive terms for describing substrates and these have had to be compared, only the following
substrate categories were used: muds (’mud’, ‘sandy mud’, ‘muddy sand’), sands (‘silty sand’,
‘sand’), and gravels (‘shelly-gravel’, ‘coarse shelly-gravel’). Other ambiguous terms (e.g. ‘sand and
shell’ or ‘mud, sand, gravel, and shell’) have not been used. Unfortunately, Crawshay (1912) made
few records of substrate types.

When sample and substrate clusters are compared (text-fig. 3a, c) there is a very close correlation.
The dense central cluster is almost entirely made up of faunas from the inshore and Eddystone
shell-gravels. Similarly, the lower cluster is mostly offshore shell-gravels and sands. The upper
cluster consists of muddy stations (with high ordinations on axis 2) and sandy stations (with low
ordinations on axis 2) with an overlap in the centre.

Water depth has a similar pattern to substrate as there is a direct, but imprecise, relation between
the two in this area of the Channel. Grain size generally decreases inshore. Finer particles are
apparently winnowed in the offshore and deposited in sheltered nearshore sites. However, inshore
there are also sand and gravel areas. The difference between the samples from the central and
bottom clusters is in water depth and distance from shore. The lower clustered sands and gravels
samples by Allen (1899) and Crawshay (1912) are from more offshore sites (text-fig. 1b) then the
Eddystone and inshore (Plymouth Sound and Stoke Point) shell-gravels of the central cluster.
Apart from this separation there is no other pattern which may be explained by the spatial siting of
samples. Therefore, the main control on clustering of stations appears to be substrate type as has
been commented on by previous authors (Ford 1923; Jones 1950; Holme 1966).

The other principle way of analysing these data is to study species occurrences (see Methods).
For this analysis, rare species (occurring in less than five of the 354 live samples) are omitted as are
those species which do not show a substrate preference. Substrate preference was defined here as
those species which occur more than 50% of the time in any one substrate.

When occurrences of species are analysed (text-fig. 4a), a pattern similar to that displayed with
substrate appears. Both the living species on sand and, to a lesser extent, the living species on

CARTHEW AND BOSENCE: RECENT SHELL-GRAVELS

253

(o)

7 00

82

148®

146 |
164

76

-1,141

■ ■

72

_59 H 42

400E7_@5?

77^U58 48 |

■ 165
• 53

0176

56

©45

2 00 -

137©

200

I

4 00

I

600

800

67

(b)

2

f

(c)

I

0 gravel species
■ sand
• mud

text-fig. 4. Plot of species as defined by their sample
occurrence. Thus species which occur in the same
samples plot together and species which occur in
different samples plot far apart, a, the same data base
of all samples (live and dead), bivalves, gastropods,
and echinoderms semi-quantitatively as used in text-
fig. 3. Although all species are used in the calculations,
only those that show a substrate preference (as listed
in Appendix 1) are drawn; the number on the plot is
the species number and refers to Appendix 1 and
Table 3. b, distribution of species; the complementary
plot to text-fig. 5, using the same data base of
all samples (live and dead), bivalves only, semi-
quantitative. As in text-fig. 4a, only bivalves that
show substrate preference have been drawn (listed in
Table 3). c, distribution of species; the complementary
plot to text-fig. 6, using the same data base of all
samples (live and dead), bivalves only, treated as
presence-absence occurrences. The species numbers
are listed in Table 3.

254

PALAEONTOLOGY, VOLUME 29

gravel plot in distinct fields. The gravel, sand, and mud species as defined by this analysis are
similar to substrate/species lists of Ford (1923) and Holme (1966) and are presented in Table 3.

The majority (29 out of 50) of the taxa which are not substrate specific by our definition (above)
are taxa which appear to avoid gravel (i.e. occur in sands and muds, e.g. Thyasira flexuosd) or
appear to avoid muds (i.e. occur in sands and gravels, e.g. Aequipecten opercularis and Ophiothrix
fragilis). The remaining taxa have too few occurrences (5-9) or too little substrate data for any
meaningful pattern to emerge.

When viewing both the sample (text-fig. 3) and species (text-fig. 4) plots the shell-gravels and
their faunas plot as distinct fields. The substrate plot (text-fig. 3c) contains both the inshore areas
of Plymouth Sound, Stoke Point, and Bigbury Bay together with those from Eddystone. This
confirms the distinctness of this fauna through time and the commonest members of this community
are listed in Table 3.

The observation of major palaeoecological importance, however, is that the dead fauna plots
centrally within this cluster and therefore gives a good representation of the community over at
least the last ninety years. These samples are not only similar to one another but their ordination
indicates an averaging of the fauna over the last ninety years. The dead fauna can therefore be
described as ‘time-averaged’ in the sense of Walker and Bambach (1971) or Warme et al. (1976).
The author (or time) contouring of the shell-gravel samples (text-fig. 3b) illustrates shifts in faunal
dominance over the last ninety years.

The earliest surveys (Allen 1899; Crawshay 1912) have low ordinations on axis I and these
samples have relatively few infaunal molluscs but are dominated by epifaunal Anomia spp. (species
number 11), Solaster papposus { 155), Marthasterias glacialis ( 158), Opliiactis balli ( 161), and Echinus

table 3. Substrate preferences of fauna (species occurring at five or more
samples, 50% or more of which are in any one substrate). Numbers refer to
species list (Appendix 1) and text-fig. 4.

Species

Species

Species.

Gravel species

No.

Sand species

No.

Mud species

No.

Glycymeris glycymeris

4

Modiolus barbatus

6

Abra nitida

67

Modiolus phaseolinus

7

Arctica islandica

23

Mya truncata

82

Lima loscombi

19

Diplodonta rotundata

25

Thracia convexa 91

Astarte sulcata

21

Lucinoma borealis

26

Philine sp.

148

A. triangularis

22

Acanthocardia echinata

33

Laevicardium crassum

35

Dosinia lupinus

42

Cardium scabrum

37

Venerupis aurea

48

Gouldia minima

39

Mysia undata

53

Dosinia exoleta

41

Gari fervensis

59

Venus casina

44

Mactra stultorum

63

V. ovata

45

Abra prismatica

66

V. fasciata

46

Hinia reticulatus

141

Venerupis rhomboides

49

Cylichna cylindracea

146

Lutraria augustior

56

Astropecten irregularis

150

Gari costulata

58

Anseropoda placenta

153

G. tellinella

60

Amphiura filiformis

164

Solecurtus scopula

62

Acrocnida brachiata

165

Spisula solida

64

Echinocardium cordatum

176

Arcopagia crassa

69

Tellina pygmaea

71

Ensis arcuatus

77

Thracia villosiuscula

92

Calliostoma zizyphinum

99

Hinria incrassata

140

Echinocyamus pusillus

174

CARTHEW AND BOSENCE: RECENT SHELL-GRAVELS

255

esculentus (171). This is clearly different from all later surveys which show a predominance of
infaunal bivalves (Table 3). It is possible here that the infauna was not well sampled because of the
use of an unmodified Naturalist’s dredge. This is the only indication we have of sampling procedure
affecting our results. The later survey of Ford (1923) sampled gravels with a similar fauna to that
found today dominated by: Musculus murmur at us, Parvicardium ovale , Callista chione, Venus oval a,
V. fasciata , Venerupis rhomboides, Lutraria angustior (L. magna of Ford), Gari costulata, G.
tellinella, Spisula elliptica , Tellina pygmaea , Ensis arcuatus , and Lunatia alderi.

Workers in the intervening periods (Smith 1932; Holme 1966) sampled a community resulting
in higher ordinations on the second axis. Smith’s (1932) centrally plotting samples are dominated
by Lima subauriculata, Astarte triangularis , Gouldia minima, Venus fasciata, Ophiura texturata,
and Echinocyamus pusillus. Similarly Holme’s (1966) samples are characterized by Aecpiipecten
opercularis, Thracia villosiuscula, Calliostoma papillosum, Asterias rubens, Ophiocomina nigra,
Amphiura chiajei , Ophiura albida, and Pseudocucumis mixta.

The samples of dead material from the three shell-gravel sites overlap almost completely with
the samples of the live faunas from these areas. The common live and dead taxa from these
centrally clustering samples include: Glycymeris glycymeris, Aecpiipecten opercularis, Cardium
scabrum, V. ovata, Venerupis rhomboides, Gari tellinella, Gouldia minima, Tellina donacina, T.
pygmaea, Arcopagia crassa, Venus casina, Laevicardium crassum, Cytharella linearis, and Nucella
lapillus, all of which are regarded as typical of the Boreal offshore gravel community of Jones
(1950).

The tight grouping of the dead samples appears to result also from a gastropod dominated dead
fauna which are not recorded live: Diadora sp., Acmaea virginea, Tricolia pullus, Alvania punctura,
Rissoa inconspicua. R. parva, R. membranacea, Bittium reticidatum, C. coarctaca, and Gibbula
cineraria', and bivalves Notirus irus and Sphenia binghami. This fauna dominated by dead gastropods
has also been recorded in previous studies of this nature (Cadee 1968; Bosence 1976). The evidence
suggests that the gastropods arrive on storm-derived weed from nearby rocky areas. Many of the
shells are small and robust and probably last a long time in the shell-gravels. In addition to the
above exotic taxa there are some molluscs in the dead fauna which are normally found in muddy
or sandy substrates: Thyasira flexuosa, Abra prismatica, Spisula subtruncata, Venurupis aurea,
Nucula sp., Corbula gibba, Turritella communis, and Lunatia alderi. These exotic taxa may represent
transported shells or short-term fluctuations in the live community not recorded in the faunal
surveys of muddy or sandy patches within the shell gravels. The latter explanation is considered
more likely as these patches are seen in bottom photographs, some of these shells are thin and
fragile and unlikely to survive much transport and there is a good historic record of the fauna from
this area.

The shell-gravel community and death assemblage can, therefore, be seen to be distinct from the
communities of the surrounding sea-floor areas. The Boreal offshore sand association (Jones 1950;
Holme 1966) accounts for many of the station plots with high axis 1 ordinations and low axis 2
ordinations. Similarly, the Boreal offshore muddy sand association is present in stations with high
ordinations on axes 1 and 2.

Although the shell-gravel community has fluctuated in faunal dominance over the last ninety
years, the accumulating dead shelly fauna provides an accurate record of the time averaging of the
live fauna.

Live and dead bivalve faunas; semi-quantitative data

Because of the poor preservation potential of the echinoderms as macrofauna and the over-
representation of gastropods in the dead fauna, it was considered useful to carry out comparisons
of all stations using only the bivalve fauna. A semi-quantitative analysis of these data (text-figs. 4b,
5) indicates that the bivalves on their own can be used in the differentiation of present-day
substrate-defined communities and that the shell-gravel community is well represented in the dead
material. The clustering along the first axis (text-fig. 5a, b, c) is very similar to that of the combined
mollusc and echinoderm fauna and both eigenvalues have almost the same variance as before
indicating little loss of information. The position and nature of clusters is similar to those from the

256

PALAEONTOLOGY, VOLUME 29

i

text-fig. 5. Contoured distribution of samples. Explanation as for
text-fig. 3, but the data base is of all samples (live and dead), bivalves
only, treated as semi-quantitative occurrences, a, density distribution
of live bivalve samples compared with dead bivalve samples. Contours
as for text-fig. 3a. b, distribution of samples by survey. Contour at 2
samples per intersection, c, distribution of samples by substrate.
Contour at 2 samples per intersection.

previous analysis with highest ordinating stations on axis 1 being the sand and mud substrate
stations of Ford (1923), Holme (1961, 1966), and Probert (1973). Axis 2 again separates out mud
(with low ordinations) and sand (with high ordinations) stations with considerable intermediate
overlap. The inversion of the ordinations compared with previous analyses (text-figs. 3, 4b) is not
significant as it is only the relative distance apart of the stations which indicate similarities and
differences.

The shell-gravel stations remain as separate clusters (text-fig. 5b, c) with the more offshore sands
and gravels of Allen (1899) and Crawshay (1912) plotting the low ordinations on axis 1.

The dead bivalve samples (text-fig. 5a) completely overlap the spread of live faunal samples from
the shell-gravels. The common fauna of the central samples of the live and dead bivalves is: Venus
ovata, Tellina pygmaea , Gari tellinella, Venerupis rhomb aides, Arcopagia crassa , Venus fasciata ,
Glycymeris glycymeris, and T. donacina. The spread of our live faunal samples from the central
cluster is by samples with abundant S. elliptica, and, to a lesser extent, Laevicardium crassum and
Lutraria angustior. Smith’s (1932) samples have lower axis 1 ordinations caused by the occurrence
of Astarte triangularis together with Modiolus barbatus , M. phaseolinus , Aequipecten opercularis.

CARTHEW AND BOSENCE: RECENT SHELL-GRAVELS

257

Lima subauriculata , and Astarte sulcata. Ford’s (1923) stations ordinate high on both axes away
from the central cluster by the occurrence of the following, often sand-living, taxa: Dosinia lupinus ,
S. subtruncata, C. gibba, Callista chione, and Parvicardium ovale. In palaeoecological studies, it is
usually assumed that the total fauna should be assessed to differentiate benthic communities. Here,
the evidence suggests that, in the absence of data on other groups, the benthic communities can be
differentiated using only the bivalves.

Presence-absence data

The data on bivalve occurrences have been transformed to a qualitative state (Table 2) to evaluate
the effect that this loss of information may have on community recognition. The analysis is
presented in text-figures 4c and 6. Again, the samples can be seen to occur in three clusters
separating out along the first axis. However, in this case the sand and mud samples are no longer
differentiated on the basis of their faunas and therefore the boreal offshore sand and muddy sand
associations can no longer be recognized.

The shell-gravel faunas, however, still plot as a separate cluster with Smith’s (1932) samples

text-fig. 6. Contoured distribution of samples. Explanation as for
text-fig. 3, but the data base is of all samples (live and dead), bivalves
only, treated as presence-absence occurrences, a, density distribution
of live bivalve samples compared with dead bivalve samples. Contours
as for text-fig. 3a. b, distribution of samples by survey. Contour at
2 samples per intersection, c, distribution of samples by substrate.
Contour at 2 samples per intersection.

258

PALAEONTOLOGY, VOLUME 29

plotting slightly off-centre (through the presence of A. triangularis and Goulciia minima). Allen’s
(1899) and Crawshay’s (1912) offshore dredge samples remain distinct.

The results presented here indicate that there is considerable information in the qualitative data
in that some of the live communities are differentiated and the live and dead bivalve faunas are
very similar. The evidence therefore suggests that in the absence of quantitative data considerable
information can still be obtained from qualitative data and its use should not be discounted.
Buzas (1972) came to similar conclusions when comparing quantitative and qualitative data on
foraminiferal distributions. The relative merits of these methods of analysis is discussed further in
Spicer (1981).

Present-day live and dead shell-gravel faunas

The analysis compares the present-day shell-gravel faunas sampled quantitatively by us in 1980-
1981. The raw data indicate that whilst the bivalves are well represented in both the live and dead
faunas there are few live gastropods ( Gibbula umbilicus , Lacuna pallidula , and Lunatia alderi) or
echinoderms (Astropecten placenta , Asterias rubens, Echinocyamus pusillus, and Spatangus pur-
pureus). However, dead gastropods are abundant and at Eddystone, twenty-two species are found
dead but none alive. The dead echinoderm fauna is always dominated by E. pusillus.

The diversity (species numbers) of the bivalves can be compared from the three shell-gravel sites
(Plymouth Sound, Stoke Point, and Eddystone) as sample sizes are constant. The fewest samples
were taken at Stoke Point (12 live and 7 dead) and therefore these can be compared with faunas
from the same numbers of samples from other areas (Table 4).

These figures confirm, along with other studies, that the diversity of the dead fauna is higher
than that of the live. It can also be seen that the Eddystone faunas today are considerably less
diverse than the Plymouth Sound and Stoke Point faunas.

At any one site only a few species are living abundantly. Glycymeris glycymeris (max. 46
individuals) is abundant at Stoke Point whilst Spisula solida is abundant in all samples from
Plymouth Sound (max. 2430). This was also found to be the case in 1923 when Ford sampled
here. At Eddystone V. fasciata (max. 10) and G. glycymeris (max. 7) are the most abundant.
These bivalves were also abundant in Ford’s (1923) survey but were only occasionally found by
Allen (1899).

table 4. Average occurrence of the live bivalve fauna in shell-gravels from the survey of 1980 1981. Data
have been combined and averaged for samples taken in November 1980, January, March, May 1981. The
average occurrence of each live species, and the standard deviation thereof, is compared between the three
areas sampled. Specimens marked * are unique to the area concerned.

Plymouth Sound
(15 samples)

Av./lOl

s.d

Stoke Av./lOl

(12 samples)

s.d.

Eddystone Av./lOl

(13 samples)

s.d.

Spisula elliplica

309

(650)

Glycymeris glycymeris

6

(13)

Venus fasciata

2-3

(3-1)

Venus fasciata

14

(11)

Venus fasciata

3-6

(3-4)

Nucula hanleyi

1-6

(1-6)

Venerupis rhomboides

4

(5)

V. ovata

3-5

(3-1)

Gouldia minima

1-2

(1-2)

Nucuta hanleyi

3

(5)

Nucula hanleyi

M

(1-9)

Glycymeris glycymeris

0-92

(1-5)

Venus ovata

1-5

(1-7)

Tellina crassa

1-1

(2)

Venerupis rhomboides

0-58

(15)

Tellina pygmaea

1

(2)

Gari tellinella

0-91

(1-5)

Venus casina

0-58

d-5)

Gari tellinella

1

(2-3)

Gardium scabrum

0-5

(1)

V. ovata

0-5

(117)

Laevicardium crassum

0-62

(2-5)

Laevicardium crassum

0 41

(0-9)

Thracia villosiuscula

0-42

(1-4)

*Cardium exiguum

0-62

(2-5)

Venerupis rhomboides

0-38

(1-1)

Arcopagia crassa

0-25

(0-62)

Arcopagia crassa

0-56

(1-4)

Tellina pygmaea

0-25

(0-86)

Spisula solida

0 16

(0-57)

Gouldia minima

018

(0-75)

Gouldia minima

0-25

(0 86)

Tellina donacina

016

(0-57)

*Ensis sp. (juv.)

018

(0-54)

Venus casina

008

(0-28)

Laevicardium crassum

0-08

(0-28)

Cardium scabrum

012

(0-3)

* Pec ten maximus

0-08

(0-28)

Glycymeris glycymeris

012

(0 5)

* Lut r aria august ior

006

(0 25)

CARTHEW AND BOSENCE: RECENT SHELL-GRAVELS

259

The dead assemblage is both more diverse and more abundant and many species occur in
hundreds and some in thousands within each 10 1 sample. S. solida dominates the Plymouth Sound
death assemblage (average 301 1 individuals per sample) but is less common elsewhere (28/sample
at Eddystone and Stoke Point). Conversely the following are very abundant (over 500/sample) at
Eddystone: Anomia sp., Pallolium tigerinum , P. simile , Cardium exiguum, Gouldia minima , V. ovata ,
and V. fasciata but only occur in tens from the other two areas.

I

3 60 -

▲

3-20 -
2 80 -
2-40 -
200 -

160 -

♦

120 -

A

♦4A

♦

A

A

A

EDDYSTONE

STOKE POINT

PLYMOUTH

SOUND

0

*

Live

A

♦

A

Dead

A

0

O

V

#

A ***

text-fig. 7. Distribution of samples in shell-
gravels based on contained species. The first and
second axes are derived from the Detrended Corre-
spondence Analysis program, and the scale is in
standard deviations. The data base is made up of
samples from the last survey, of 1980-1981, of
live and dead samples of bivalves, treated fully
quantitatively. The plot shows the relation between
provenance of the samples, and live and dead
bivalve numbers.

0-80 -

0 40 -

0 -
0

0-40 080 120

1-60 200

2

Although visual assessment of the raw data picks out some of the differences between the bivalve
faunas from these three shell-gravel sites when the total faunal occurrences are compared by
correspondence analysis, they are found to have a considerable amount of similarity. The fully
quantitative comparison of live and dead faunas from these three areas is illustrated in text-figure
7. The three areas plot in overlapping fields spread by variation along axis 1. This coincides with
shallow-to-deep water and inshore to offshore variation from Plymouth Sound (low ordinations)
to Eddystone (high ordinations).

When the shell-gravel fauna is viewed on its own and not in relation to faunas from the
surrounding substrates, it is seen that the dead fauna does not plot as a single central grouping but
plots with the live fauna from that area. Therefore, when considered in relation to the surrounding
faunas the live and dead shell-gravel community is a distinct grouping: when considered in isolation
each area has its own live faunal variation which is reflected in the accumulating shelly material.

260

PALAEONTOLOGY, VOLUME 29

Qualitative and semi-quantitative comparisons of the faunas from these three areas were also
undertaken. These analyses show a similar separation of the live faunas but the dead faunal
separation is lost and all dead faunal samples plot in a separate field with little variation. These
analyses stress the importance of quantitative palaeoecological data to obtain the maximum
information concerning the live fauna.

DISCUSSION

This analysis demonstrates a considerable degree of confidence in community reconstruction from
dead material because the relative abundances of the time-averaged living species are preserved in
the dead assemblages. This result differs from our previous work (e.g. Bosence 1979a, b) because of
scale. When communities are sampled in detail on a scale of tens of hundreds of metres, with
sampling over a short period (less than a year), then major differences between live fauna and dead
material are found. There appears to be considerable post-mortal mixing from adjacent areas and
from different live faunas. If, however, the sampling is on a larger scale, of kilometres or tens of
kilometres and over a long period of time, then the correspondence between live and dead faunas
becomes more precise; the fluctuation and vagaries of live populations have been ironed-out. The
dead fauna may bear no relation to any community at any one instant, but to the community’s
median position over a period of time; or, ‘time-averaged’ in the sense of Walker and Bambach
(1971).

The presentation of these fluctuations in community composition will depend on sedimentation
rates. Although sedimentation rates from the English Channel shell-gravels have not been studied,
data from algal gravels from the west or Eire, which have many taxa in common (Bosence 1976,
1980) have molluscan production rates of 15 g/CaC03/m2/yr. Assuming density of material of
2-5 g/cm3 and 60% porosity, this would give rise to an accumulation rate equivalent to 6 mm every
100 years. Therefore one shell thickness may have been deposited during the eighty-year period
of sampling in these shell-gravels. Farrow et al. (1984) give similar rates for shell-gravels from the
Scottish shelf averaging 3-31 mm/ 100 yrs. Very slow sedimentation rates are also suggested from
the radiocarbon dating of shells from the British shelf carried out by Wilson (1982) and Sturrock
(1982) who have dates ranging from 10 920+ 150 to 960 + 50 years B.P.

This information on sedimentation rates illustrates the impossibility of preserving information
on population fluctuations or on any biotic interactions (cf. McCall and Tevesz 1983). A caveat
must arise here as to the limits of the usefulness of time-averaged data; whilst soft substrate
‘communities’ may be recognized, and possibly their long-term changes recognized, the dynamic
nature of communities will be lost.

The fluctuations in the benthic fauna recorded over the last ninety years coincide with fluctua-
tion in the planktonic communities in the Western Channel. Southward (1962, 1980) records a
Sagitta elegans community in the 1920s which was replaced by S. setosa in the 1930s to 1960s.
The Celtic Sea S. elegans community reappeared in the late 1960s and has continued to today. The
changes in planktonic communities have been correlated with changes in water temperature in
the Western Channel (Southward 1980) with S. elegans inhabiting the warmer Celtic sea waters.
Holme (1983) has shown how the arrival of predatory starfish (Luidia ciliaris and L. sarsi ) in
the late 1960s possibly from the Celtic Sea is thought to have caused a decline in Ophiothrix beds
in this area. Our data indicate fluctuations in faunal dominance coincident with these previously
recorded changes.

CONCLUSIONS

1. Three major communities can be recognized by multivariate statistical analysis of semi-
quantitative faunal records from the area offshore from Plymouth. These are the ‘Boreal offshore
muddy sand’, ‘Boreal offshore sand’ (Jones 1950), and the shell-gravel communities.

2. The above communities can also be differentiated on the basis of the bivalve fauna only. The

CARTHEW AND BOSENCE: RECENT SHELL-GRAVELS

261

shell-gravel community can be differentiated from the sand and mud communities using just the
presence/absence data of the bivalves.

3. The dead shell-gravel faunas are indistinguishable from the live shell-gravel faunas in this
analysis and therefore the shell-gravel community is being preserved as a distinct and recognizable
assemblage. This agrees with Holme’s (1961, p. 443) statement that: ‘There is no evidence that dead
shells are transported any appreciable distance from the areas in which they originally lived.’

4. Despite the shifts in the composition of the live faunas over the last ninety years the present-
day dead fauna show less spread, or greater homogeneity, than the live faunas. The accumulating
death assemblage can be said to be ‘time-averaging’ (Walker and Bambach 1971 ) the changing live
faunas.

5. The historic records of the live shell-gravel faunas over the last eighty years indicates
fluctuating populations with similar faunas in 1932 and 1966, and in 1923 and 1980.

6. There are minor qualitative and quantitative differences between the faunas from the shell-
gravel sites of Eddystone, Stoke Point, and Plymouth Sound. A quantitative analysis of live and
dead faunas from these three locations indicates a different live fauna and death assemblage from
each site, the death assemblages being more similar to the live fauna from each site than to live or
dead faunas from other sites, i.e. differences in occurrences and abundances between sites are
preserved in the dead faunas.

7. In terms of Wilson’s (1982) model of shell-gravel formation this correspondence between live
and dead faunas suggests that the gravels are in the mature stage of shell-gravel development. The
gravels are inhabited by live fauna which can tolerate the coarse substrate, with additional dead
shells derived from nearby rocky areas.

Acknowledgements. Our thanks go to Dr Norman Holme (Marine Biological Association, Plymouth) for
helpful discussion and logistical support throughout the course of this work and to Joy Mellows-Facer who
undertook the lengthy programme of sampling material for the last faunal survey. We also acknowledge with
thanks the co-operation and support provided by Professor J. E. Denton, FRS Director, Marine Biological
Association, Plymouth. Our thanks also go to Drs Paul Grant (Imperial College, London) and Bob Spicer
(Goldsmiths’ College, London) for invaluable assistance with multivariate programs and to Drs Simon Kelly
and Simon Conway-Morris (University of Cambridge) for helpful discussion on earlier drafts of this paper.
Finally, we wish to thank Sheila Ripper for drafting the text-figures.

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Typescript received 23 January 1985
Revised typescript received 16 June 1985

RICHARD CARTHEW

Department of Earth Sciences
University of Cambridge
Downing Street
Cambridge CB2 3EQ

DAN BOSENCE

Department of Geology
Goldsmiths’ College
Rachel McMillan Building
Creek Road
London SE8 3BU

264

PALAEONTOLOGY, VOLUME 29

APPENDIX 1

List of species, authors, and numbers used in faunal analysis (text-fig. 4),together with total live and dead
occurrences, occurrence by sample for each author and substrate, and substrate occurrences for each live species.

Occurrence by sample, i.e. presence/absence

Species — i o

BIVALVIA

1. Nucula sp.

126

24

3

1

49

7

10

5

6

21

31

37

18

19

2. Striarca lactea (Linnaeus)

2

25

5

1

1

2

3. Area tetragona (Poli)

5

8

2

3

2

4. Glycymeris glycymeris (L.)

52

24

3

16

11

1 1

2

9

39

1

4

5. Modiolus modiolus (L.)

9

7

1

4

5

6. M. barbatus (L.)

1

1

1

1. M . phaseolinus ( Philippi)

21

9

19

1

1

7

1

1

8. Musculus marmoratus (Forbes)

1 i

25

7

4

3

3

1

2

9. Mytilus edulis L.

2

1

1

1

1

10. Ostrea edulis L.

1

1

1

1

11. Anomia sp.

41

22

11

30

10

5

3

12. Chlamys varia ( L.)

1

1

13. C. distorta (da Costa)

2

12

2

1

1

14. Aequipecten opercularis (L.)

63

22

18

30

6

1

7

1

17

11

3

11

15. Pallolium tigerinum (Muller)

15

21

7

8

5

3

2

16. P. simile (Laskey)

2

10

2

2

17. Pec ten maximus (L.)

29

4

11

16

1

1

9

3

6

18. Lima hians (G melin)

2

1

2

1

19. L. loscombi Sowerby

11

4

5

4

2

6

1

2

20. L. subauriculata (Montagu)

1

1

1

2 1 . Astarte sulcata (da Costa)

23

4

15

4

12

4

22. A. triangularis (Montagu)

18

6

18

18

23. Arctica islandica (L.)

9

1

1

5

2

1

5

2

1

24. Thyasira flexuosa (Montagu)

53

3

40

7

2

4

20

20

8

25. Diplodonta rotundata (Montagu)

12

6

8

4

1

7

2

1

26. Lucinoma borealis ( L.)

26

3

1

10

8

7

15

4

7

27. Myrtea spinifera (Montagu)

12

3

11

1

1

4

6

28. Kellia suborbicularis (Montagu)

9

3

5

4

2

2

3

29. Lepton squamosa (Montagu)

3

3

2

1

3

30. Mysella bidentata (Montagu)

37

30

1

1

5

17

13

3

31. Tellimya ferruginosa (Montagu)

9

7

1

1

4

3

1

32. T. substriata (Montagu)

4

3

1

2

1

33. Acanthocardia echinata (L.)

49

1

2

1

30

6

9

1

1

27

9

6

34. Parvicardium ovale (Sowerby)

9

6

6

3

4

2

3

35. Laevicardium crassum (Gmelin)

24

12

6

4

2

1

4

7

15

2

4

36. Cardium exiguum Gmelin

2

16

1

1

1

1

37. C. scabrum Philippi

17

23

10

1

1

12

1

3

38. C. tuberculatum Jeffreys

1

1

1

39. Gouldia minima (Montagu)

34

23

1

2

7

13

11

31

2

40. Callista chione (L.)

2

3

2

2

4 1 . Dosinia exoleta (L.)

14

11

1

2

11

8

2

42. D. lupinus (L.)

53

1

27

12

12

1

4

27

8

10

43. Venus verrucosa L.

3

2

1

1

1

1

1

44. Circomphalus ( Venus) casina (L.)

29

14

1

12

4

7

3

3

21

2

2

45. Timoelea ( Venus) ovata (Pennant)

82

25

2

5

46

11

1

3

14

42

13

6

12

Substrate

U

o

tL.

O

X

0

1

a

CARTHEW AND BOSENCE: RECENT SHELL-GRAVELS

265

Occurrence by sample, i.e. presence/absence

VO

VO

OV

Species

Live

occurrences

Dead

occurrences

Allen

Crawshay

Ford

Smith

Holme 1959

Holme 1961

Probert

This paper

Gravel

46. Claunirella (Venus) fasciata (da Costa)

84

24

3

3

22

1 1

1

3

41

73

47. Chamelea ( Venus) striatula (da Costa)

43

43

48. Papina ( Venerupis) aurea (Gmelin)

9

10

2

5

2

49. P . rhomboides ( Pennant)

44

25

3

2

17

3

1

2

16

32

50. Venerupis pullastra ( M ontagu )

2

2

51. V. saxatilis ( Fleuriau)

1

1

52. Notirus irus (L.)

3

53. Mvsia undata (Pennant)

6

1

1

4

54. Lutraria lutraria ( L.)

23

19

1

3

1

55. L. angustior Philippi

2

11

1

1

2

56. L. magna (da Costa)

9

9

7

57. Gari depressa (Pennant)

2

2

58. G. costulata (Turton)

12

1

3

5

1

2

6

59. G. fervensis (Gmelin)

1 1

3

4

1

4

2

60. G. tellinella (Lamark)

39

25

20

2

1

7

9

30

61 . Solecurtus chamasolen (da Costa)

22

11

5

6

3

62. 5. scopula (Turton)

6

4

6

4

63. Mactra corallina ( L.)

31

28

1

2

64. Spisula solida ( L.)

50

24

3

24

23

38

65. S. subtruncata (da Costa)

22

7

22

66. Abra prismatica (Montagu)

36

3

1

23

6

3

3

67. A. nitida (Muller)

7

4

3

68. A. alba (Wood)

87

71

1

6

3

6

1

69. Arcopagia crassa (Pennant)

28

18

1

1

13

2

2

3

6

26

70. Tellina donacina L.

12

12

4

1

2

4

1

2

71. T. pygmaea Loven

33

15

17

7

2

7

27

72. T. fabula Gmelin

15

3

9

1

2

3

73. T. squalida Montagu

1

1

74. Donax vittatus (da Costa)

3

3

75. Phaxas pellucidus (Pennant)

105

76

12

10

7

3

76. Ensis ensis ( E.)

29

23

2

2

1

1

4

77. E. arcuatus (Jeffreys)

16

2

12

1

1

2

10

78. E. siliqua (L.)

4

2

1

1

2

79. Hiatella arctica ( L.)

19

9

16

i

2

8

80. H. striata (Fleuriau)

9

8

i

2

81 . Corbula gibba (Olivi)

46

12

43

3

2

82. Mva truncata L.

6

6

83. Sphenia binghami (Turton)

5

84. Barnea parva (Pennant)

1

1

1

85. Pholadidea loscombiana Turton

1

1

1

86. Lyonsia norwegica Macgillivray

4

1

1

2

1

87. Pandora pinna (Montagu)

3

1

2

88. Cochlodesma praetenue (Montagu)

1

1

1

89. Thracia phaseolina (Lamark)

2

2

90. T. pubescens (Montagu)

1

i

91. T. convexa (Wood)

5

3

2

92. T. villosiuscula (Macgillivray)

10

11

3

6

1

6

GASTROPODA

93. Emarginula reticulata Sowerby

94. E. conica Lamark

95. Diodor a apertura (Montagu)

9 13 7 2

111 1

8

Substrate

1

19 1 1

7 2

1 2

4 1

10 8

1

2

2 3

7

4 1

3 8

21 6
2 2

8 8

26 3

7

32 23

4 1

1 1
9 4

2

39 22

16 3

2

1

4

3

20 13

3

2

3

1 1
I

1 3

3

6

10

7

2

1

1

4

1

3

7

2

5

5

6

24

3

3

29

4

4

1

4

8

3

1

7

1

Unassoc’d

266

PALAEONTOLOGY, VOLUME 29

Species

Occurrence by sample, i.e. presence/absence

23 o Q

VO

VO

Ov

Substrate

O

-d

3

s

gastropoda (cont.):

96. Patella intermedia Jeffreys

97. Patina pellucida (L.)

98. Acmaea Virginia (Muller)

99. Calliostoma zizyphinum (L.)

100. C. papillosum (da Costa)

101. Cantharidus montgui (Wood)

102. C. striatus (L.)

103. Monodonta lineata (da Costa)

104. Gibbula magus ( L.)

105. G. cineria (L.)

106. G. umbilicalis (da Costa)

107. G. tumida (Montagu)

108. Tricolia pullus (L.)

109. Lacuna pallidula (da Costa)

1 10. Littorina saxatilis (Olivi)

111. L. littoralis ( L.)

112. A Ivania crassa (Kanmacher)

113. T. punctura (Montagu)

1 14. Rissoa crassa (da Costa)

115. R. inconspicua Alder

116. R. parva (da Costa)

117. R. membranacea (Adams)

118. Turrit ella communis Risso

1 19. Aporrhais pespelecani (L.)

120. Bittium reticulatum (da Costa)

121 . Triphora perversa (L.)

122. Clatlirus clathrus (L.)

123. C. lurtonis (Turton)

1 24. Eulima glabra (da Costa)

125. Balds alba (da Costa)

126. Lunatia catena (da Costa)

127. L. alderi (Forbes)

128. L. montagui (Forbes)

129. Calyptraea chinensis (L.)

1 30. Capulus ungaricus ( L.)

131. Erato voluta (Montagu)

132. Trivia sp.

1 33. Lamellaria perspicua (L.)

1 34. Simnia patula ( Pennant)

135. Trophon muricatus (Montagu)

136. Ocenebra erinacea ( L.)

137. Coins gracilis ( da Costa)

138. Buccinum undatum L.

139. Coins jeffreysianus (Fischer)

140. Hinia incrassata (Strom)

141. H. reticulatus (L.)

142. Cytharella coarcta (Forbes)

143. C. linearis (Montagu)

144. Philbertia gracilis (Montagu)

145. Acteon tornatilis (L.)

146. Cylichna cylindracea (Pennant)

2

13

8 12 3 5

7 4 3

2 2

2
3

12

15

1 16

1 1

13

1 5

1

3 1 I

I 3

1

1

1

15

10

15 6 2 2

3 4 3 3

15

1 7 1

2

1 1

1

4 5 2 2

2 2

36 17 1 1

2

1 1

5 2 5

1

8 8 6 2

5 3 2

8 13 5

1

1 10 1

17 1 16

1 1

20 12 8

6 14 2 2

1 1 1

8

1 16 1

1 3 1

I

15

1

9 2

1

2

16 2 1 4 2

2

1

2

7 4

1

9 2 4

1

15 2 6

1 1 I

I

1

1 2

1 1

9 15 12 4 3

1 1

1

1 4

1 3 2

1 3 2

3 4

8 1

1

4 5 6

3 2

17 11

1

I

1

9 3 3

CARTHEW AND BOSENCE: RECENT SHELL-GRAVELS

267

Species

Occurrence by sample, i

.e. presence/absence

Live

occurrences

Dead

occurrences

Allen

Crawshay

Ford

Smith

Holme 1959

Holme 1961, 1966

Probert

This paper

Gravel

Substrate

C 3

£ S

Unassoc’d

1 47. Scaphander lignarius ( L. )

4

4

1

l

i

148. P Inline sp.

12

9

1

2

3

7

1

ECHINODERMATA

149. Antedon bifida (Pennant)

2

2

2

150. Astropecten irregularis (Pennant)

26

12

5

i

8

2

13

2

5

151. Luidia sarsi Diiben and Koren

4

2

2

1

1

152. L. ciliaris (Philippi)

15

15

3

1 53. Anseropoda placenta (Pennant)

13

6

5

2

3

8

1

1 54. Porania pul villus ( M idler)

11

3

8

1

1

2

1 55. Solaster papposus (L.)

25

13

12

4

5

5

1 56. Henricia sanguinolenta ( M idler)

11

5

6

5

3

157. Asterias rubens L.

49

15

19

3

1 1

i

10

16

i

5

1 58. Marthasterias glacialis ( L. )

27

14

13

6

10

5

1 59. Ophiothrix fragilis ( Abildgaard)

48

16

13

10

1

5

3

10

19

i

9

1 60. Ophiocomina nigra (Abildgaard)

83

9

63

2

9

29

9

10

161 . Ophiactis halli (Thompson)

44

1 1

32

1

13

5

7

162. Amphiura chiajei Forbes

1

1

1

163. A. securigera (Diiben and Koren)

2

2

1

1

164. A.filiformis (Midler)

47

1

27

5

7

7

3

23

9

8

165. Acrocnida brachiata (Montagu)

7

1

2

4

5

1

166. Amphipholis squamata (Delie Chiaje)

1

i

1

167. Ophiura texturata Lamark

69

14

12

25

4

9

5

14

31

7

1 1

168. O.albida Forbes

34

10

15

6

3

12

7

3

4

169. O. affims Liitken

17

1

2

1

10

2

1

3

10

1

1

1 70. Psammechinus miliaris (Gmelin)

17

13

2

1

1

4

6

5

171. Echinus esculentus L.

39

12

26

1

10

6

7

172. E.acutus Lamark

16

7

9

2

3

4

173. Echinocyamus pusillus (Midler)

90

25

7

4

31

21

6

4

17

57

13

1

13

1 74. Spatangus purpureus ( M idler)

30

7

14

4

1

1

3

16

3

4

175. Echinocardium cordatum (Pennant)

61

2

37

10

8

4

1

33

10

14

176. E. fla vescens ( M id ler )

5

4

1

4

1

1 77. E. pennatifidum (Norman)

2

i

1

2

178. Holothuria forska/i Dclle Chiaje

1

1

1

179. Cucumaria elongata Diiben and Koren

30

22

1

3

5

3

8

11

6

1 80. C. hyndmani Thompson

1

1

181. C. lac tea (Forbes)

6

6

3

3

1 82. Thyone fusus ( M idler)

10

1

2

2

1

4

3

1

4

183. T. raphanus Diiben and Koren

2

i

1

1

1

184. Pseudocucumis mixta Ostergren

3

3

3

I Leptosynapta inhaerans (Midler)

M

12

I ]

8

1

1 5

10

4

1 Lahidoplax digitata (Montagu)

268

PALAEONTOLOGY, VOLUME 29

APPENDIX 2

Details of locations of stations (text-tig. 2) as Decca positions (as read)

and transits.

Author’s station
number

Depth

Red Green Purple

Direction of towing

Eddystone: Allen (1899)

55

64 m

All-7 D 33 0 A 74-4

A 1 17

87

60 m

A 10 5 D 30-6 A 74-65

A 10 5

88

60 m

All-7 D 30-5 A 72-7

Eastwards

89

60 m

A 10 0 D 31-5 A 76-0

A 10 0

Stoke Point
1

32nr

D 33-8 A 72-2

Line up gun and

point

2

35 -]- m

D 33-8 A 72-2

Stoke Campsite just

open

3

23]- m

D 32-0 A 70-3

All towing to land

Author’s station
number

Depth

Transits

Direction of towing

Plymouth Sound Ford ( 1923)

23

14 m

Duke Rock buoy on Bovi-
sand Point

Western Breakwater Light-

Towards Plymouth

house on New Gravel
buoy

47

15 m

Mewstone on 4th block-

house from lighthouse
western end of break-

water

Towards Plymouth

Left-hand victualling yard

chimney on Barn Point
light beacon

90

14 nr

New Ground buoy under

inner end of Batten
Breakwater

Towards Plymouth

Top of Mewstone on 2nd

block-house west end of
breakwater

Qu 3

15 nr

Line buoy with left-hand
side of Fort

Tall flats on east end of

Towards Plymouth

Drakes Island.

EARLY EOCENE INSECTIVORES (MAMMALIA)
FROM THE PEOPLE’S REPUBLIC OF MONGOLIA

by D. E. RUSSELL CUld D. D ASHZEVEG

Abstract. The early Eocene insectivores of the Tsagan-Khushu locality in Mongolia are described. Two new
genera and species of Nyctitheriidae, Bumbanius rarus and Oedolius perexiguus , and two new genera and
species of Palaeoryctidae, Naranius infrequens and Tsaganius ambiguus are described and compared. A panto-
lestid similar to Palaeosinopa and an unidentified form bearing a resemblance to Hyracolestes are also dis-
cussed. This study indicates that the early Eocene insectivores of Mongolia were not strongly endemic and
probably participated in the Holarctic faunal distribution through Europe and North America.

The early Eocene part of the Mongolian Naran-Bulak Formation, the Bumban Member, has
furnished a varied fauna. Elements of this assemblage have been described (Dashzeveg, 1976, 1977,
1979n, b\ Dashzeveg and McKenna 1977) in articles that establish its relationship to the Holarctic
fauna known in the Ypresian of Europe and the Wasatchian of North America. An analysis of the
faunas of the Naran-Bulak Formation was presented by Dashzeveg (1982). Continuing research
and screen-washing techniques by one of us (D. D.) have produced the small mammals described
below.

The material was collected from two quarries in the Bumban Member at Tsagan-Khushu (see
text-figs. 1, 2). At Quarry 1 the fossiliferous sediments consist of lenses of sandy gravel conformably
overlying the compact green clays of the Naran Member. Tapiroids {Homogala. y), hyracotheres
{Hyrac other ium), hyopsodont condylarths ( Hyopsodus ), eurymylids ( Gomphos ), rodents (Ctenodac-
tylidae), primates ( Altanius ), and lizards, birds, small gastropods, and ostracods have been found.
Quarry II, also situated near the limit of the Naran and Bumban Members, was discovered 250 m
south of Quarry I. Again, the fossiliferous sediments consist of sandstone and gravel; rodents,
condylarths, primates, tapiroids, and other groups have been recovered from here, as well as
salamander and bird remains.

The specimens described here (and measured in millimetres) are the property of the Mongolian
Academy of Sciences, Institute of Geology, Palaeontology and Stratigraphy Section and bear the
catalogue numbers of the latter (prefixed PSS).

SYSTEMATIC PALAEONTOLOGY

Order Lipotyphla Haeckel, 1866
Family Nyctitheriidae Simpson, 1928
Bumbanius gen. nov.

Type species. Bumbanius rams n. sp.

Diagnosis. Dental formula ?-?-4-3. P/2 and P/3 unreduced and biradicular; P/2 subequal to P/3.
P/4 with large low paraconid, large high metaconid, and small talonid slightly basined lingually,
with single median cusp at extremity of anteroposteriorly directed cristid obliqua. M/1 -M/3 all
approximately same length; cusps rather massive; paraconid large and low situated; strong antero-
cingulum; metaconid largest trigonid cusp; oblique groove present between summit of metaconid
and anterior extremity of cristid obliqua; wide basined talonid; hypoconid biggest (and highest)
talonid cusp, with hypoconulid intermediate and entoconid smallest; entoconid situated obliquely

| Palaeontology, Vol. 29, Part 2, 1986, pp. 269 291.]

270

PALAEONTOLOGY, VOLUME 29

text-fig. 1. Sketch map of the Nemegt Basin, Mongolian People’s Republic, showing the situation of Tsagan-
Khushu and the other Palaeogene localities of Naran-Bulak and Ulan-Bulak (modified from Gradzinski et al.
1969), with the region indicated in a general map of Mongolia.

at posterolingual corner of talonid, slightly posterior with respect to hypoconid; M/3 hypoconulid
short but prominent.

Etymology. Named for the Bumban Member of the Naran-Bulak Formation.

Bumbanius rarus sp. nov.

Text-figs. 3 and 4

Holotype. Specimen PSS 20-96, right mandibular fragment with M/1 -M/3.

Referred material. PSS 20-88, right mandibular fragment with P/4 and alveoli of P/2-P/3; PSS 20-66, right

RUSSELL AND DASHZEV EG: EOCENE INSECTIVORESFROM MONGOLIA

271

n

o •

- o.

o -

2

o o

© e

3

—

4

o o
o o

5

<8>

text-fig. 2. Stratigraphic sections showing the position of the fossiliferous
deposit within the Naran-Bulak Formation at the outcrops of Tsagan-
Khushu. i, at Quarry I; n, at Quarry II; 1, green clay of the Naran Member;
2, fossiliferous lenses of reddish sand and sandstone; 3, red clay of the
Bumban Member; 4, Quaternary sands and gravels; 5, fossil locality.

mandibular fragment with P/4-M/1; PSS 20-69, left mandibular fragment with M/2; PSS 20-131, right
mandibular fragment with M/3; PSS 20-57, left maxillary with M1/-M2/ and roots of P3/-P4/ and M3/; PSS
20-68, left M2 /.

Locality and horizon. Tsagan-Khushu, Nemegt Basin, People’s Republic of Mongolia; Naran-Bulak Forma-
tion, Bumban Member, Quarry I (PSS 20-66, PSS 20-69, PSS 20-57) and Quarry II (PSS 20-88, PSS 20-96).

Age and distribution. Early Eocene of the Naran-Bulak Formation at Tsagan-Khushu.

Diagnosis. As for genus.

Etymology, rarus, Latin; so named because of its relative infrequency in the fauna.

Description. The mandible is long and low and is preserved (in composite) between the posterior alveolus of
P/1 and the level of M/3; a single mental foramen is visible below the posterior root of P/3 and the symphysis
extends to below the anterior part of P/2. P/2 and P/3 are not known, but from the ridges separating the 4
empty alveoli in front of P/4 both of these teeth must have possessed 2 roots; the crown length of each was
not much less than that of P/4. With respect to the vertical axis of the mandible, the crowns of P/4- M/3 are
tilted lingually; with respect to the vertical plane of the symphysis, the teeth are vertical and the mandible is
tipped labially.

P/4 (text-fig. 3a, c) is dominated by a high, narrow protoconid; the well-detached metaconid is nearly as
high as the protoconid; a vertical anterior crest on the protoconid joins at its base a large, rather transverse

212

PALAEONTOLOGY, VOLUME 29

paraconid, situated low on the crown. A short anterocingulum is present. The talonid is short and basined
only lingually, being divided by an anteroposteriorly directed cristid obliqua. The posterolingual limiting crest
of the talonid is variably developed, but no cusp is formed; only a single median cuspule is present at the
extremity of the cristid obliqua.

text-fig. 3. Bumbanius rarus gen. et sp. nov. a and c, PSS 20-88, right P/4; a , lingual
view; c, occlusal view, x 20. b and d, PSS 20-69, left M/2; b, lingual view; d , occlusal
view, x 20. e and /, PSS 20-96, right M/1 -M/3, holotype; e , lingual view; /, occlusal
view, x 20. All specimens are from Tsagan-Khushu, Naran-Bulak Formation, Bumban
Member, MPR, and are housed in the Institute of Geology, Ulan Bator.

RUSSELL AND D ASHZEVEG: EOCENE INSECTIVORES FROM MONGOLIA

273

The molar trigonids (text-fig. 3 b-f) are of moderate height; a moderately strong but crestiform paraconid,
situated well below the metaconid, projects anteriorly and connects with the sharp anterior vertical crest of
the protoconid. The trigonid basin is well developed and closed lingually to a variable degree according to
the tooth in the molar series. The talonid is long and broadly basined; the talonid cusps decrease in size
from the hypoconid to the entoconid; the hypoconulid and entoconid are joined by a higher crest than
that between the hypoconid and the hypoconulid. The anterocingulum is consistently present and (in
one out of three specimens) can continue labially below the protoconid; postero-cingular development is
very slight.

A left maxillary, PSS 20-57 (text-fig. 4), with M1/-M2/ and the roots of P3/-P4/ and M3/ is considered as
possibly referable to B. rams. It occludes fairly well with the only left molar in the collection, PSS 20-69.
From the roots of P3/ this tooth was principally elongate with little lingual expansion of the protocone. Apart
from the evident fact that the P4/ was an approximately triangular tooth, little can be said of it except that it
was proportionally similar to the P4/ of Leptacodon : narrow but rounded lingually, with a metastylar lobe
considerably longer and larger than that of the parastyle.

text-fig. 4. Bwnbanius varus gen. et sp. nov. PSS 20-57, left Ml/-
M2/, occlusal view, x20. From Tsagan-Khushu, Naran-Bulak
Formation, Bumban Member, MPR.

Ml/ and M/2 are transversely elongate with an anteriorly directed parastyle, a larger metastylar lobe, and
complete absence of a mesostyle. The labial border is gently indented; slight basining occurs labial to the
metacone. The paracone is considerably higher and more voluminous than the metacone; they are well
separated at their base. A sharp crest connects the metastyle and the metacone; a slighter, labially directed
crest extends between the summit of the paracone and a point posterior to the parastyle. The conules are well
developed, with the paraconule being the larger and higher. Crests diverge from the paraconule to join the
lingual base of the paracone and the anterior tip of the parastyle. The premetaconule crista is rather weak
and extends to the anterolingual side of the metacone; the postmetaconule crista extends posterolingually at
the base of the metacone and disappears before reaching the metastyle. A deep trigon basin is formed between
and labial with respect to the conules. The protocone is as high as the paracone and has a long sloping lingual
surface. Far below the summit of the protocone a small and somewhat cuspate hypocone occurs at the lingual
extremity of a strong posterior cingulum. The anterior cingulum is short and weak. From the position of its
roots, M3/ was a triangular tooth with a strongly sloping posterolabial border.

A second specimen of the upper dentition, PSS 20-68, appears to be an upper M2/ referable to B. varus. It
has been damaged labially, but size and most of its features are compatible. Some differences translate
individual variation within the species and the specimen is of interest for this reason. Cingular development

274

PALAEONTOLOGY, VOLUME 29

is stronger, with the hypoconal shelf being wider; both it and the antero-cingulum extend farther lingually

than on the tooth of PSS 20-57. Also, the premetaconule crest is

more pronounced, as were, apparently, the

conules.

Measurements.

Length

Width

PSS 20-57; Ml/

2-15

2-45

M2 /

2-35

2-9

PSS 20-66: P/4

1-8 est.

105

M/1

1-8 est.

1-2

PSS 20-69: M/2

1-9

1-25

PSS 20-88: P/4

1-9

10

PSS 20-96: M/1

1-9

1-2

M/2

1-9

1-2

M/3

1-9

1-2

PSS 20-131: M3/

1 -85 est.

1-2

Comparisons. P/4 differs from that of Leptacodon (only L. tener and L catalus) in having a larger
paraconid and metaconid and in having an anteroposteriorly directed cristid obliqua. M/1 differs
from that of Leptacodon in having a more anteriorly directed paraconid. M/l-M/3 differ from those
of Leptacodon in the placement of the entoconid slightly posterior with respect to the hypoconid
and situated obliquely at the posterolingual corner of the talonid; it is separated by a U-shaped
notch (not a V) from the trigonid. Also, the hypoconulid is higher and slightly larger than the
entoconid. B. rarus is bigger than Leptacodon but very close in size to Praolestes.

Apart from size Praolestes also shows a similarity that could translate familial affinity; on the
generic level, however, it is very distinct. The P/4 of Bumbanius differs in being longer and lower
with its paraconid larger and situated much lower on the crown, its metaconid larger and relatively
much higher above the top of the paraconid, and it differs in the point of contact of its cristid obliqua
(which is anteroposteriorly oriented), far below the median side of the metaconid, being more labial.
However, in occlusal view, for example, the morphology of both the trigonid and talonid in the
two forms follows a similar pattern. The talonid appears to be longer in Bumbanius , but it is
damaged in Praolestes. Both animals show a well-developed oblique groove across the posterior
trigonid wall of M/1.

Concerning the referred upper dentition, P3/ has a weaker lobe than in Leptacodon and the tooth
as a whole is situated less obliquely than in the latter; in PSS 20-57 (text-fig. 4) the labial border of
P3 / follows the orientation of the same border of P4/, which would indicate the presence of a wider
snout.

While similar in general morphology to the upper teeth of Leptacodon , those of PSS 20-57 possess
a higher protocone with a lingually longer sloping surface; the paracone, on the other hand, is lower
and less slender; the metacones in the two taxa are more closely alike. The anterior cingulum is
weaker than in the upper molars of Leptacodon , as is the labial cingulum labial to the paracone; in
contrast, it is more basined labial to the metacone than in Leptacodon.

An interesting comparison can be made with the type mandible of Adunator lehmani from the
middle(?) Palaeocene of Walbeck, Germany. The general configuration of P/4-M/3 is similar in
the two forms. Differences in B. rarus include, for P/4, a bigger metaconid and a reduced talonid
basin; for M/l-M/3, higher cusps in general, larger paraconid, a broader trigonid basin, hypoconid
situated posteriorly with respect to the entoconid, entoconid smaller and hypoconulid bigger,
and a narrower notch between the entoconid and the metaconid. The M/3 is relatively bigger in
Bumbanius.

The two animals are subequal in size and share, among other features, an oblique groove parallel
to the anterior end of the cristid obliqua that extends to the summit of the metaconid.

Pending knowledge of the upper teeth in Adunator , present evidence suggests that it and Bumba-
nius could be members of the same family.

Some resemblances in Bumbanius may be also noted to Centetodon, but as with many of the
above comparisons the characters are probably mostly primitive for lipotyphlans.

RUSSELL AND DASHZEVEG: EOCENE INSECTIVORES FROM MONGOLIA

275

Oedolius gen. nov.

Type species. Oedolius perexiguus n. sp.

Diagnosis. Dental formula 3- 1 -4-3. P/1 small and uniradicular. P/2 and P/3 larger than P/1,
biradicular and subequal in size. P/4 with small, low paraconid, lack of metaconid, lack of
talonid basining and with a single, small median cusp at posterior extremity of tooth. M/l-M/3 all
approximately same length (or, M/3 the longest); cusps slender and moderately high; paraconid
low but prominent; strong anterocingulum; protoconid and metaconid subequal; strong oblique
groove present below summit of metaconid, emphasized by anterior part of cristid obliqua. Molars
relatively narrow; hypoconid most voluminous talonid cusp but equalled in height (or exceeded) by
hypoconulid; entoconid small, situated obliquely at posterolingual corner of talonid, slightly pos-
terior with respect to hypoconid. M/3 hypoconulid short to moderately developed but prominent.

Etymology. Oedolius, from the name of the locality of Oedol, not far from Naran-Bulak.

Oedolius perexiguus sp. nov.

Text-fig. 5

Holotype. Specimen PSS 20-103, left mandibular fragment with M/l-M/2 and talonid of P/4.

Referred material. PSS 20-71, left mandibular fragment with bases of M/2-M/3; PSS 20-74, right mandibular
fragment with M/2; PSS 20-76, left mandibular fragment with damaged P/4-M/2 and alveoli of P/1 -P/3; PSS
20-77, right mandibular fragment with P/4 and alveoli of P/ 1 -P/3; PSS 20-78, right mandibular fragment with
talonid of M/3; PSS 20-80, left mandibular fragment with M/2-M/3; PSS 20-86, left mandibular fragment
with damaged M/2-M/3 and talonid of M/1; PSS 20-87, left mandibular fragment with M/3; PSS 20-92, right
mandibular fragment with M/3 and talonid of M/2; PSS 20-94, left mandibular fragment with M/1, trigonid
of M/2 and alveoli of 1/1 P/4; PSS 20-102, right mandibular fragment with M/2-M/3; PSS 20-104, left
mandibular fragment with P/4-M/1; PSS 20-108, right mandibular fragment with M/3; PSS 20-111, right
mandibular fragment with P/4-M/1.

Locality and Horizon. Tsagan-Khushu, Nemegt Basin, People’s Republic of Mongolia; Naran-Bulak Forma-
tion, Bumban Member; Quarry 1 (PSS 20-71, PSS 20-74, PSS 20-76, PSS 20-77, PSS 20-78, PSS 20-80, PSS
20-102, PSS 20-103, PSS 20-104) and Quarry II (PSS 20-86, PSS 20-87, PSS 20-92, PSS 20-94).

Age and distribution. Early Eocene of the Naran-Bulak Formation at Tsagan-Khushu.

Diagnosis. As for genus.

Etymology, perexiguus , Latin; very small.

Description. The mandible is long and low; mental foramina occur below P/1 or P/2 and below the posterior
side of P/3; the latter is much the smaller. The symphysis extends posteriorly to the level of P/2. The alveoli of
three incisors are present, in decreasing proclivity from 1/1 to 1/3, and appear to have been all about the same
size. From the alveolus the canine was large and single rooted; a single rooted, relatively large P/1 followed it.
In PSS 20-94 the P/2 and P/3 were only slightly smaller than the P/4, but in PSS 20-76 the mandible is
considerably shorter and the P/2 and P/3 are accordingly quite smaller teeth; below the premolar alveoli,
however, the mandible is higher than in PSS 20-94. A third specimen, PSS 20-77, displays the tooth and jaw
proportions of PSS 20-94. In all specimens the P/2 and P/3 are subequal in size. With respect to the vertical
axis of the mandible the crowns of M/l-M/3 are tilted lingually; with respect to the vertical plane of the
symphysis the teeth are vertical and the mandible is tipped labially.

P/4 (text-fig. 5c) is essentially a single cusped tooth; the paraconid is very small and situated very low on
the crown and there is no metaconid. The dominant protoconid is moderately high and recurved along its
anterior border. A sharp crest descends posterolingually from its summit, delimits the lingual side of the
talonid and joins the single, median cuspule at the rear of the talonid; the latter is completely unbasined and
slopes labially from the lingual crest.

In the molars (text-fig. 5 a-d) the metaconid and protoconid are moderately high and are subequal. An
anterior crest on the protoconid joins the labial base of the paraconid crest, with which it makes a rather
sharp angle. The paraconid is low, about as high as the hypoconulid, and projects anteriorly. The metaconid

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PALAEONTOLOGY, VOLUME 29

text-fig. 5. Oedolius perexiguus gen. et sp. nov. a and c, PSS 20-80, left
M/2- M/3; a, lingual view; c, occlusal view, x 20. b and d, PSS 20-103, left
talonid of P/4, M/1 M/2, holotype; b , lingual view; d, occlusal view, x 20.
e, PSS 20-77, right P/4, lingual view, x 20. All specimens are from Tsagan-
Khushu, Naran-Bulak Formation, Bumban Member, MPR, and are housed
in the Institute of Geology, Ulan Bator.

is situated slightly posterior with respect to the protoconid and is traversed obliquely by a strong groove that
extends from its summit to the labial base of the tooth. The cristid obliqua forms the lingual border of this
groove and reaches high on the metaconid. The talonid is a little wider than the trigonid in M/1 and a little
narrower in M/2. The hypoconid is the major cusp, with the large and medianly placed hypoconulid being
subequal in height. The entoconid is the smallest of the three and is situated at the posterolingual corner of
the tooth opposite the hypoconid. The talonid is deeply basined but nearly lacks a lingual wall. A broad U-
shaped notch separates the entoconid and the metaconid. The hypoconulid of M/3 is narrow but prominent
(in 3 out of 4 specimens). A noteworthy tongue and groove effect is achieved by the fit of the hypoconulid of
the preceding tooth between the paraconid and the large anterior cingulum of the succeeding one; this is true

for P/4-M/3.
Measurements.

Length

Width

PSS 20-77: P/4

1 25

0-55

PSS 20-94: M/1

1-4

0-8

PSS 20-102: M/2

1 -25 est.

0-9

M/3

1-5

0-9

PSS 20-111: P/4*

1 25

0.55

PSS 20-74: M/2

1 35

0-85

PSS 20-108: M/3

1 35

0-9

PSS 20-87: M/3

1-35

0-85

PSS 20-92: M/3

1 -3 est.

0-9

PSS 20-76: P/4

10

0-55

PSS 20-104: P/4

105

0-5

M/1

11

0-75

PSS 20-103: M/1

1-4

0-9

PSS 20-80: M/2

14

0-9

M/3

1-5

0-8

* Associated with M/1, but the molar is damaged and was not measured.

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Comparisons. P/4 of O. perexiguus differs from that of B. ranis by its smaller paraconid, absence of
metaconid, and absence of talonid basining. The molars differ by being narrower and by having
more slender cusps; they differ also in the angle made by the anterior protoconid crest and the
paraconid crest, by the protoconid and metaconid being subequal, by the cristid obliqua being
stronger anteriorly and reaching higher on the trigonid, and by more separation of the hypoconulid
and the entoconid. Oedolius is considerably smaller than B. rams.

The P/4 (text-fig. 5e ) of O. perexiguus differs from that of Leptacodon by its smaller paraconid,
lack of metaconid, lack of talonid basining, and presence of a small, single, median talonid cusp.
M/1 -M/3 (text-fig. 5 a-d) differ from those of Leptacodon by having a slightly thinner and higher
protoconid and metaconid, by the small size and oblique placement of the entoconid, slightly
posterior with respect to the hypoconid (it is anterior in Leptacodon ), and the presence of a wide U-
shaped notch between it and the metaconid, and by the relatively large size of the medianly placed
(not closer to the entoconid) hypoconulid. O. perexiguus is about the same size as Leptacodon but
the molars are a little narrower.

Praolestes (except for paraconid development) is much closer to B. rarus than to O. perexiguus.
Hyracolestes is like neither, nor are the various erinaceids and dormaaliids that are known; the
same can be said for the divers Chinese Palaeocene and Eocene forms that are either not comparable
due to lack of lower dentitions or are dissimilar. None of the North American or European
nyctitheres are as close to O. perexiguus as is Leptacodon.

Principally because of the unbasined talonid of the P/4 of Oedolius and its lack of a metaconid
comparison with palaeoryctids and pantolestids was made. Certain points of resemblance exist with
Thylesia among the former but nothing notable in lower molar morphology suggests a relationship
to pantolestids. Oedolius may not fit with certitude in the concept of the Nyctitheriidae as it is
presently known, but for time being, lacking a better designation, we place it in that family.

The same could be said concerning the single (and damaged) specimen of Kashanagale from the
late Palaeocene Gashato locality (Szalay and McKenna 1971 ). Although the latter was described as
an anagalidan, we doubt that attribution. The M/3 is shorter in Kashanagale than in Bumbanius
and the cristid obliqua does not extend as high on the trigonid walk but otherwise the morphology
of M/2 and M/3 (the only teeth comparable) is quite similar.

Nyctitheriidae gen. indet.

Text-fig. 9/

Material. PSS 20-60, isolated right upper M 1/; from Quarry I, Tsagan-Khushu.

PSS 20-60 (text-fig. 9 f), is little worn hut it has undergone postfossilization abrasion along the labial
border, particularly at the extremity of the metastyle, which has been reduced also by breakage at its base.
Occlusionally, nearly the total length of the metastyle is preserved, as the wear facet is intact. In basal outline
the metastyle undoubtedly projected more labially than its present extension; the parastyle was also prominent
but probably followed the present contour. There is wear along the anteroposterior crests of the paracone-
metacone, but even taking that into account the paracone is the higher and the more tubular of the two and
the metacone the more elongate anteroposteriorly; furthermore, the two cusps differ considerably in orien-
tation, with the paracone sloping labially and the metacone being nearly vertical. The posterolingual side of
the metacone forms, with the metastyle, a high shearing surface; a pronounced notch separates the two.
Conules are strongly developed and situated approximately opposite each other; the paraconule is much the
larger and is connected to the base of the paracone by a low crest and to the anterior side of the parastyle by
the preparaconular crest. The metaconule is a sub-circular, pointed cusp and is completely isolated from both
the metacone and the metastyle. A sharp indentation in the tooth outline occurs at this point, marking the
limit of the hypoconal shelf, although a basal cingulum persists for a short distance along the base of the
metacone. The hypoconal shelf is quite wide and supports not only a large hypocone, but also (labial with
respect to the latter) a second well-developed cusp. The hypocone extends hngually beyond the level of the
protocone. A short but prominent anterocingulum occurs at the anterolingual corner of the protocone and
produces, with the hypocone, a squared look to the lingual basal profile of the tooth. The protocone has
undergone much wear, coupled perhaps with breakage, but appears to have been originally lower than the
labial cusps.

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PALAEONTOLOGY, VOLUME 29

Measurements. Length Width

PSS 20-60: Ml/ 3 1 est. 3-3 est.

Comparisons. PSS 20-60 is much larger than Bumbanius and Oedolius and incompatible with Nara-
nius and Tsaganius. The upper teeth referred to Bumbanius represent a much more primitive
stage of development (more transversely elongated, little shearing adaptation of the metastyle, less
cingular expansion, and the anterocingulum more labially situated). No close relation is evident.

Comparison with the pantolestids and leptictids (including the Pseudorhyncocyoninae of Europe),
both of which resemble to some degree PSS 20-60, was unfruitful, although a rather striking
similarity was found in the upper DP4/ of Leptictis , even to the presence of two cusps on the
hypoconal shelf. PSS 20-60 is not a deciduous tooth and is not related to the Proteutheria. In basic
morphology it strongly resembles Eocene nyctitheres, but no one known form is significantly close.
Despite the presence of an enlarged hypoconal lobe in the enigmatic Sarcodon , there is no pertinent
resemblance between it and PSS 20-60. It is hoped that additional material of this taxon will be
found that will enable a fuller description to be made and its affinities more precisely deduced.

A fragmentary left lower molar, PSS 20-70 (text-fig. 9b, c), with the talonid and metaconid
preserved, shows characters strongly reminiscent of those of the lower molars of B. rams. Its size,
however, is much greater than that of the latter and thus suggests a possible affinity with the upper
molar, PSS 20-60.

The Talonid of PSS 20-70, very well preserved, differs from that of the lower molars of B. rarus
in that the hypoconulid is relatively larger, situated more medianly, and in consequence further
from the entoconid. It is intermediate in height between the hypoconid (the highest and biggest)
and the entoconid. The latter, also, is relatively larger, as is the hypoconid which is expanded
anteriorly. The cristid obliqua differs in orientation, being directed more lingually and extends
toward the summit of the metaconid emphasizing a strongly marked oblique groove. This groove
and the disposition and size of the talonid cusps is consistent with our assignment of Bumbanius,
and this specimen, to the Nyctitheriidae.

Mention should also be made of Sarcodon and Hyracolestes with respect to PSS 20-70. While
there is no question of the latter being referable to Sarcodon, it is approximately the same size as
the M/1 in AMNH 21732, the posterior trigonid wall appears to be crossed by a similar groove
extending between the cristid obliqua and the summit of the metaconid, and the trigonid cusps are
quite similarly distributed and have like proportions. The hypoconid was probably the highest
talonid cusp in Sarcodon (it is broken in the single specimen known) and the hypoconulid is large
and intermediate in height. But in strong contrast to PSS 20-70 the entoconid of Sarcodon is much
closer to the hypoconulid. Apart from this feature, there is nothing in the (admittedly too meager)
sample of each that would deny relationships between them.

Also furnishing speculation for affinity is the morphology of comparative parts of the first
molar in Hyracolestes. Though the animal was smaller than that represented by PSS 20-70 and the
talonid is damaged (hypoconid broken off; entoconid possibly reduced by erosion) the available
evidence does suggest that, possibly, PSS 20-70 and Hyracolestes were related. At the same time the
hypothesis arises that Sarcodon and Hyracolestes might share a common relationship.

Lipotyphla indet.

Text-fig. 6

Material. PSS 20-62, fragment of a right maxillary with M2/-M3/ and the lingual half of Ml/; from Quarry I,
Tsagan-Khushu.

The presence of the maxillary fragment PSS 20-62 indicates the existence of a lipotyphlan in the fauna of
Tsagan-Khushu that is not represented in the collection by lower teeth. Its size is not compatible with the
species of either Bumbanius or Oedolius. The heavy wear that the teeth of PSS 20-62 have undergone does not
facilitate analysis.

The maxillary fragment (text-fig. 6) contains only M2/-M3/ and the lingual half of Ml/; no alveoli of the

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279

text-fig. 6. Lipotyphla indet., PSS 20-62, right M 1/-M3/,
occlusal view, x 20. From Tsagan-Khushu, Naran-Bulak
Formation Bumban Member, MPR.

premolars remain. The teeth are transversely elongate with expansion of a posterior cingular shelf on Ml/
and M2/; apparently no hypocone was developed. On M2/ the cingulum is nearly continuous across the base
of the protocone. The anterior cingulum is rather weak although a marked concavity occurs between the
labial limit of the cingulum and the base of the parastyle. The metaconule was apparently crestiform and
included in the postprotocrista; it does not seem to have had a premetaconular crest directed toward the base
of the metacone. The paraconule was probably larger and seems to have been situated more labially. Between
the conules the bottom of the trigon basin is raised in a transverse, low rounded ridge that extends between
the protocone and a point between the bases of the paracone and metacone. The latter cusp is considerably
the smaller of the two and is inclined posteriorly; the paracone is more vertical. Both have long, sloping
lingual surfaces. Wear has produced a deep, U-shaped groove between them, but originally their bases were
probably much closer. Relative to the transverse diameter of the teeth their labial length is rather short. A
shallow ectoflexus separates the styles in M2/ and is barely indicated in M3/. From the position of the roots
the parastyle of Ml / was rather strongly directed anteriorly and the metastyle labially. In M2/ the parastyle is
of moderate dimensions and is also directed anteriorly; the metastyle is directed posterolabially and is con-
nected to the metacone by a short crest. The occlusal surface of the parastyle has been worn off. M3/ remains
a rather large tooth despite the absence of a metastyle and practically no posterior cingular development.

Measurements. Length Width

PSS 20-62: M2/ 1 65 2-55

M3 / 145 2-1

Comparisons. Due to a superficial resemblance to various Proteutheria, PSS 20-62 was compared
with leptictids and pantolestids, but no affinity to these groups is evident. Palaeoryctids can also
be eliminated, and among the Lipotyphla, only the Nyctitheriidae or the Geolabididae seem to
show a relationship. Although not strikingly similar, PSS 20-62 most resembles Leptacodon among
nyctitheres. Comparison with early Eocene geolabidids is not possible since upper molars have
not been described for Centetodon patratus and C. neashami. The earliest available information is
furnished by the middle Eocene C. pulcher and C. bembicophagus. The lingual or protoconal root
is not yet, or only incipiently, divided in these species, contrasting with the condition in younger
members of the genus and agreeing with the condition in PSS 20-62. C. pulcher upper molars are
distinguished by marked but narrow pre- and postcingula and a broad labial shelf. Also, a small
but distinct hypocone is present. In PSS 20-62 the labial shelf is narrower, the precingulum less
developed, and the postcingulum is wider and lacking a hypocone. The upper molars of the middle
Eocene Centetodon are more transversely elongate than those of Leptacodon but less than in

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PALAEONTOLOGY, VOLUME 29

PSS 20-62. A slight lingual cingulum encircling the protocone occurs in PSS 20-62 and is variably
present in C. pulcher. Although rather heavily worn, it would appear that the paracone-metacone
were connate at their base in PSS 20-62, as in Centetodon rather than in Leptacodon. Centetodon is
characterized by a flaring postmetacrista, which in PSS 20-62 is extremely short and little developed,
but in Leptacodon it takes a different form with more of a notch between the metastyle and the
metacone. A small stylocone, just posterior to the parastyle, occurs in C. pulcher and a suggestion
of a similar feature might occur in PSS 20-62; on the other hand, it could be an artifact of wear. It
does not appear in Leptacodon.

Comparison was also made with various dormaaliids, in particular with Scenopagus and Macro-
cranion , but many of the dissimilarities that separate PSS 20-62 and Leptacodon can also be cited
for these forms. The paracone-metacone are not connate in dormaaliids and the hypocone is
generally high and prominent.

The Asian Tupaiodon , although more likely an erinaceid, was also examined and found very
different.

In conclusion, the facts tend to indicate the possible attribution of PSS 20-62 to the Geolabididae,
but the evidence is still weak and uncertain. For the moment, we will refer the specimen to
Lipotyphla indet.

Order Proteutheria

Family Palaeoryctidae (Winge, 1917) Simpson, 1931
Subfamily Didelphodontinae Matthew, 1918
Naranius gen. nov.

Type species. Naranius infrequens n. sp.

Diagnosis. Dental formula 3- 1-4-3. P/1 uniradicular, P/2 and P/3 small, biradicular, and subequal
in size. P/4 with minute basal paraconid, no anterocingulum, no metaconid, no talonid basining
but talonid traversed medianly by a crest with a moderately developed cusp at its posterior extremity.
M/1 and M/2 of approximately same length; M/3 longest; cusps moderately slender and moderately
high; paraconid relatively high and small; strong anterocingulum; protoconid and metaconid sub-
equal; no oblique groove on posterior surface of metaconid; cristid obliqua contact low on trigonid
and slightly labial with respect to protoconid-metaconid notch; hypoconid biggest (and highest)
talonid cusp, with hypoconulid intermediate and entoconid smallest; entoconid situated at postero-
lingual corner of talonid, opposite hypoconid. M/3 with long, narrow talonid and large prominent
hypoconulid.

Etymology. Named after the Naran stream.

Naranius infrequens sp. nov.

Text-fig. la-g

Holotype. Specimen PSS 20-73, left mandibular fragment with P/3-M/1 and alveoli of P/1 and P/2.

Referred material. PSS 20-64, isolated right M/1; PSS 20-72, left mandibular fragment with P/2-P/3; PSS 20-
75, left mandibular fragment with P/4-M/2; PSS 20-79, right mandibular fragment with M/3; PSS 20-81, left
mandibular fragment with talonid of M/2 and M/3; PSS 20-82, left mandibular fragment with talonid of M/2
and M/3; PSS 20-83, right mandibular fragment with talonid of M/1 and damaged M/2; PSS 20-84, right
mandibular fragment with damaged M/2 and M/3; PSS 20-90, right mandibular fragment with damaged M/2
and talonid of M/3; PSS 20-91, edentulous left mandibular fragment; PSS 20-93, right mandibular fragment
with talonid of M/1, damaged M/2, and alveoli from posterior side of canine to anterior root of M/1; PSS 20-
97, right mandibular fragment with M/2-M/3; PSS 20-105, left mandibular fragment with damaged M/2; PSS
20-106, left mandibular fragment with talonid of M/2 and M/3; PSS 20-109, right mandibular fragment with
damaged M/2 and M/3; PSS 20-1 12, right mandibular fragment with talonid of M/2 and roots of M/3; PSS
20-1 13, right mandibular fragment with M/1 and damaged M/2; PSS 20-121, right mandibular fragment with
P/4-M/2 (all without enamel).

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text-fig. 7. Naranius infrequens gen. et sp. nov. a , PSS 20-126, left M1/M2/, occlusal view, x 20. b
and c. PSS 20-72, left P/2-P/3; b , lingual view; c, occlusal view, x20. cl and e, PSS 20-73, left P/3-
M/1, holotype; d, lingual view; e, occlusal view, x 20. f and g, PSS 20-97, right M/2-M/3;/, lingual
view; g, occlusal view, x 20. All specimens are from Tsagan-Khushu, Naran-Bulak Formation,
Bumban Member, MPR, and are housed in the Institute of Geology, Ulan Bator.

Locality and horizon. Tsagan-Khushu, Nemegt Basin, People’s Republic of Mongolia; Naran-Bulak Forma-
tion, Bumban Member, Quarry I (PSS 20-64, PSS 20-72, PSS 20-75, PSS 20-79, PSS 20-81, PSS 20-82, PSS
20-83, PSS 20-84, PSS 20-105, PSS 20-106, PSS 20-109, PSS 20-1 12, PSS 20-113) and Quarry II (PSS 20-90,
PSS 20-91, PSS 20-93, PSS 20-97).

Age and distribution. Early Eocene of the Naran-Bulak Formation at Tsagan-Khushu.

Diagnosis. As for genus.

Etymology, infrequens , Latin; rare.

Description. The mandible is long and low; mental foramina occur below the anterior border of P/2 and below
the posterior part of P/4; the latter is much the smaller. The symphysis extends posteriorly to the level of P/2.

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PALAEONTOLOGY, VOLUME 29

The alveoli of three incisors are preserved; all three teeth appear to have had about the same proclivity with
1/2 apparently the largest. From the alveolus the canine was large and single rooted; a relatively large, single
rooted P/1 closely followed it. P/2 and P/3 (text-fig. lb, c) are considerably smaller than P/4 and apparently
smaller than P/1. They are biradicular, subequal in size, and morphology with a small, unbasined talonid
traversed medianly by a slight anteroposterior crest terminating posteriorly in a minute cusp. In orientation
the premolars continue the vertical axis of the mandible, but the molars are tipped lingually; with respect to
the vertical plane of the symphysis the premolars are tipped and the molars vertical.

P/4 (text-fig. Id, e ) is essentially a single cusped tooth; a minute paraconid occurs low on the crown and a
metaconid is lacking. The dominant protoconid is moderately high and recurved. A posterolingual crest
descends the protoconid but is not continued by the talonid crest. The latter, oriented slightly obliquely,
divides the unbasined talonid into unequal parts and terminates in a moderately high median cusp.

In the molars (text-fig. Id-g) the protoconid and metaconid are moderately high and are subequal. The
anterior crest of the protoconid joins the labial base of the paraconid, with which it makes a flat angle. The
paraconid is relatively high situated but is small and projects little anteriorly. The protoconid is posterior with
respect to the metaconid. Cristid obliqua contact with the posterior trigonid wall is low. The talonid is slightly
wider than the trigonid in M/1 and subequal in M/2. The hypoconid is the principal talonid cusp, with the
large and medianly placed hypoconulid being only a little less high. The entoconid is the smallest of the three,
but it is considerably higher than that of Oedolius perexiguus. It is situated at the posterolingual corner of the
tooth, but being round it does not give the impression of being obliquely placed; it is slightly posterior with
respect to the hypoconid. The talonid is deeply basined but lacks a lingual wall; a broad U-shaped notch
separates the entoconid and the metaconid. M/3 is characterized by a long, narrow talonid, with no (or
extremely little) lingual prominence of the entoconid.

The fragment of maxillary, PSS 20-126 (text-fig. la), containing Ml/ and M2/ and two alveoli of P4/, might
be a little large for attribution to N. infrequens, but it occludes fairly well and the teeth are of corresponding
morphology. Ml / and M2/ are strongly transversely elongated and narrow anteroposteriorly lingual to the
paracone and metacone. The latter are moderately high and slender and situated close together; the paracone
is the bigger and higher of the two. It is unconnected with the parastyle, which in Ml/ is directed anteriorly;
strong transverse wear has eliminated details on the parastyle. In M2/ this style forms a large lobe, directed
anterolabially; a simple cuspule crowns its occlusal surface. The metacone and metastyle are connected by a
high crest that is slightly concave anterolabially in Ml/; the stylar lobe, directed posterolabially, is devoid of
cusps or cingula. In M2/ the lobe is directed more labially and the crest from the metacone is notched where it
is joined by the postmetaconular crest (but in neither tooth is a deep notch developed in the metacrista as it is
in Cimolestes). A deep, asymmetrical labial notch (ectoflexus) is formed between the stylar lobes. The para-
conule is faintly developed, being little more than a minor elevation in the preprotocrista; a short, faint crest
is visible at the base of the paracone, testifying to the probable former presence of a postparaconular crest.
The metaconule is more prominent, but again, it is not cuspate and forms an elongate thickening in the
postprotocresta; there is no trace of a premetaconular crista. The protocone is subequal in height to the
paracone; in lingual view it is nearly vertical and in M2/ it even leans slightly posteriorly. A slight, but long
basal precingulum is present as well as an even longer postcingulum; the latter develops a narrow shelf
lingually, on which occurs, squaring the posterolingual corner, a cuspule.

From the two remaining alveoli, P4/ was as wide (transversely) as the anterior part of the first molar.
Presumably, the two labial roots were widely spaced; indicating a rather triangular tooth.

Measurements.

Length

Width

PSS 20-72; P/2

0-5

0-35

P/3

0-5

0-4

PSS 20-73: P/3

0-5

0-3

P/4

11

0-6

M/1

1-4

0-85

PSS 20-106: M/3

1 45

0-9

PSS 20-81: M/3

1 -5 est.

0-95

PSS 20-79: M/3

1-55

0-9

PSS 20-84: M/2

1-25

0.85

M/3

1-5

0-85

PSS 20-113: M/1

1 45

0-85

M/2

1-45

0-85 es

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PSS 20-109: M/2

1-2

1-2

M/3

1-4

-

PSS 20-82: M/3

1-5

0-95

PSS 20-64: M/1

1 4 est.

0-85

PSS 20-75: P/4

1-2

0-6

M/1

1-2

0-8

M/2

1 -2 est.

0-85

PSS 20-97: M/2

14

10

M/3

1-55

10

PSS 20-126: Ml /

1-4

2-0

M2 /

1-25

2-2

Comparisons. Except for being less than half the size of the late Cretaceous Procerberus formicarum
the lower molars of N. infrequens are quite similar. Less resemblance can be seen in the Cretaceous
species of Cimolestes but Batodon tenuis (recently referred to the Geolabididae; Novacek 1976;
Krishtalka and West 1979) is also similar and is of a comparable size; the latter differs in possessing
a P/2 and P/3 more anteriorly inclined, P/4 with a small metaconid, M / 1 -M /2 with a larger but lower
situated paraconid, an apparently weaker entoconid, and sometimes a V-shaped notch between the
entoconid and the metaconid instead of an open U. The M/3 has a shorter talonid and a more
prominent entoconid.

Among the early Tertiary forms the middle Palaeocene Palaeoryctes puercensis is too advanced
morphologically, but a species from Silver Coulee (late Palaeocene) shows a little more similarity.
Differences include premolar loss, P/3 bigger, P/4 with a relatively large and high situated paraconid,
considerably higher trigonids, and M/3 with a shorter talonid. The relatively low crowned N.
infrequens is not close to these forms.

Mention could be made of certain similarities in the type specimen of the middle Palaeocene
Avunculus , but most of these can be regarded as familial in nature. The same comment can be made
for Thelvsia (late Palaeocene). None of the other forms presently classified as palaeoryctids shows
a significant similarity to a closer degree. Palaeoryctidae from the late Palaeocene of Morocco were
cited in preliminary note (Cappetta et al. 1978), but the lower molar illustrated seems to be better
placed in the Nyctitheriidae.

Concerning Eocene taxa, a non-molariform P/4 prompted research among the Pantolestidae;
Bessoecetor diluculi (sometimes referred to Propalaeosinopa ) in particular possesses morphological
aspects reminiscent of those found in N. infrequens , but general differences are too great for affinity.
Closer similarity is present in the various species of Centetodon , especially in the lower molars; their
trigonids are often much like those in N. infrequens, as is the feeble entoconid development on the
talonid. The hypoconulid tends to be more lingual in position, however, and the P/4 more molari-
form. So far, nothing resembling the distinctive upper molars of the Geolabididae has been found
in Mongolia; we prefer to regard N. infrequens as referable to the Palaeoryctidae. None of the
described insectivores from China or elsewhere in Asia shows a relationship to N. infrequens.

Comparison of the possibly referable maxillary, PSS 20-126, reveals (as for the lower dentition)
more similarity with late Cretaceous palaeoryctids than with younger forms. Also, as with the lower
molars, Cimolestes resembles less our specimen than does Procerberus , having stronger conules, a
slightly greater stylar shelf development, and a more pronounced notch (in labial view) in the
metacrista. Anteroposterior narrowness of the upper molars lingual to the paracone-metacone is
variable in both Procerberus and Cimolestes, but the latter tends to have more sharply pointed
cusps and to be slightly more adapted for shearing. N. infrequens would be more like Cimolestes in
this respect. Little is known of the upper molars of Batodon , but, like N. infrequens, they are more
transversely elongate than in Cimolestes and Procerberus. They differ from those of N. infrequens
in having stronger conules, a wider labial shelf, and a shallower ectoflexus in M2/. In all three
Cretaceous genera variably developed anterior and posterior cingula are present; they are sometimes
absent and sometimes form an uninterrupted shelf across the lingual side of the protocone. Although

284

PALAEONTOLOGY, VOLUME 29

nothing corresponding exactly to the cuspule in the position of a hypocone (when is a hypocone
recognizable?) in the upper molars of N. infrequens was noted in the genera in question, the
morphology seen in N. infrequens is not surprising for a palaeoryctid.

The early Tertiary species of Palaeoryctes and Cimolestes differ considerably in upper molar
characters, while the other palaeoryctids are even further removed (in the instances where the upper
teeth are known, for example Didelphodus , Acmeodon , Aaptoryctes). Those of Centetodon differ in
having a lower, less tubular paracone-metacone, stronger conules, a more developed labial shelf
and, especially, by the progressive development of two lingual roots. Although a hypocone is
lacking, a cuspule can sometimes develop at the lingual extremity of the posterocingulum in a
fashion similar to that in N. infrequens.

Tsagcmius gen. nov.

Type species. Tsaganius amibiguus n. sp.

Diagnosis. Dental formula ?- 1-4-3. P/1 uniradicular. P/2 biradicular and small. P/3 almost as large
as P/4. P/4 with anterocingulum well below level of paraconid; distinct paraconid reaching to
about half the height of protoconid; strong metaconid nearly as high as protoconid; talonid not
basined and traversed medianly by a crest terminating posteriorly in a large cusp. M/1 and M/2
relatively short and of approximately same length; M/3 longest; cusps high and slender; paraconid
moderately high and small; strong anterocingulum; protoconid and metaconid subequal; no oblique
groove on posterior surface of metaconid; cristid obliqua contact low on trigonid and labial with
respect to the protoconid-metaconid notch; talonid relatively short; hypoconulid highest cusp
with hypoconid slightly lower and entoconid lowest; entoconid situated at posterolingual corner
of talonid, opposite hypoconid. M/3 with narrow talonid and short and moderately prominent
hypoconulid.

Etymology. From tsagan , Mongol; meaning white.

Tsaganius ambiguus sp. nov.

Text-fig. 8 a-f

Holotype. Specimen PSS 20-89, left mandibular fragment with talonid of P/4, M/I M/3.

Referred material. PSS 20-67, right mandibular fragment with talonid of M/1, M/2 M/3, and alveoli of P/4;
PSS 20-1 15, left mandibular fragment with P/4 and alveoli of P/1 -P/3 and M/l-M/2.

Locality and horizon. Tsagan-Khushu, Nemegt Basin, People’s Republic of Mongolia. Naran-Bulak Forma-
tion, Bumban Member, Quarry I (PSS 20-67, PSS 20-115) and Quarry II (PSS 20-89).

Age and distribution. Early Eocene of the Naran-Bulak Formation at Tsagan-Khushu.

Diagnosis. As for genus.

Etymology, ambiguus , Latin; meaning uncertain or enigmatic.

Description. The mandible is long and low; mental foramina occur below the posterior part of P/2 and below
the anterior part, or middle of M/1 . The symphysis extends posteriorly to the level of P/2. Only the alveoli of
the anterior premolars are preserved; P/1 was apparently about the size of P/2 but possessed a single root;
P/2, biradicular, was considerably smaller than P/3, which was apparently nearly as big as P/4.

Lacking the entire row of alveoli one cannot, of course, be certain of the identity of the teeth that occupied
those that remain. The above interpretation is, we think, the most probable, but in the case where the most
anterior preserved alveolus would be that of the canine we would suppose that the P/1 is lost; the two small
alveoli that follow almost certainly belong to a two-rooted tooth and this tooth would be P/2.

P/4 (text-fig. 8c, /) has a well-developed trigonid with a distinct paraconid that is nearly vertical in orien-
tation. Like all the trigonid cusps (and those of the molars) it is slender and approaches a tubular aspect. In
height it probably equalled that of the hypoconulid (which is damaged in PSS 20-115), reaching to about
halfway up the protoconid. A short but distinct anterocingulum occurs labial with respect to the paraconid

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285

and well below it. The talonid is rather short and the terminal cusp (preserved in the holotype) is a large, high
cusp fitting snugly between the anterior cingulum and the base of the paraconid of M/I . The anteroposterior
crest traversing the talonid is rather low and divides it into unequal parts.

In the molars (text-hg. 8 a-d) the paraconid and metaconid are of subequal size, but the posteromedian
crest of the metaconid is characterized by a slight concavity in unworn specimens (visible in anterior or
posterior view). The anterior crest of the protoconid forms a nearly straight line with the crest of the paraconid;

text-fig. 8. Tsaganius ambiguus gen. et sp. nov. a and h, PSS 20-89, left talonid of P/4, M/1 -M/3,
holotype; u, lingual view; />, occlusal view, x 20. c and d , PSS 20-67, right talonid of M/1, M/2-M/3;
c, labial view; d , occlusal view, x 20. e and /, PSS 20-1 15, left P/4; e, lingual view; /, occlusal view,
x 20. All specimens are from Tsagan-Khushu, Naran-Bulak Formation Bumban Member, MPR,
and are housed in the Institute of Geology, Ulan Bator.

as the crests connecting the protoconid and metaconid form an even straighter line, the trigonid in occlusal
view forms a distinctive narrow V in contour. The paraconid is moderately high, relatively small, and projects
little anteriorly. The paraconid and metaconid are opposite each other. Cristid obliqua contact with the
posterior trigonid wall is low. Talonid trigonid widths are subequal in M/1; the talonid is slightly the narrower
in M/2. The hypoconid is relatively small, although remaining the principal talonid cusp in volume; the
medianly placed hypoconid is slightly higher, however. The entoconid is small and barely cuspate; in occlusal
view it terminates a straight crest from the hypoconulid and is situated opposite the hypoconid. A fairly wide
U-shaped notch separates the entoconid and the metaconid. The talonid of M/3 is narrow but only a little
longer than those of the preceding molars. Its minute and nearly crestiform entoconid produces a bulge in the
lingual border of the talonid and maintains, with the moderately prominent hypoconulid, a straight connecting
crest.

The P/4 and the molars are tipped lingually with respect to vertical axis of the mandible.

286 PALAEONTOLOGY, VOLUME 29

Measurements.

Length

Width

PSS 20-67: M/2

0-9

0-65

M/3

0-9

0-65

PSS 20-89: M/1

10

0-7

M/2

0-95

0-73

M/3

103

0-6

PSS 20- 115: P/4

0-95

0-6

Comparisons. At first glance Tsaganius appears quite close to Naranius , but detailed examination
reveals a large number of distinctive characters. The difference in size of P/2 and P/3 and the
tricuspid trigonid of P/4 are immediately notable. The molars differ less, but the anteroposteriorly
narrow, symmetrically sided V of the trigonid occlusal surface, and its more slender cusps are
noteworthy; on the talonid the high hypoconulid and the weaker entoconid also constitute differ-
ences, and the M/3 talonid is shorter and less linear lingually. The far posterior position of the
posterior mental foramen is unusual in insectivores (cf. Thelysia Gingerich, 1982, a possible palaeo-
ryctid), although typical of Pantolestidae.

Among the Cretaceous palaeoryctids, Batodon furnishes the most similarities, but differs in having
P/2 and P/3 of subequal length, in lacking an anterocingulum on P/4, in possessing a definite
angulation at the junction of the anterior protoconid crest and the paraconid crest, and a larger
talonid; in M/3 the talonid is both longer and wider with a strong notch between the entoconid
and the hypoconulid. Nevertheless, its small size, its slender trigonid cusps and molar talonid
configuration, and the comparable molariform state of its P/4, lead one to envisage a similar sort
of ancestor for Tsaganius. There are no described intermediate forms from the Palaeocene; in fact,
we know of no other taxon that approaches so closely the dental morphology (as it is known today)
of T. ambiguus.

Family Pantolestidae Cope, 1884, gen. indet.

Text-fig. 9 a

Material. PSS 20-95, isolated right upper Ml / or M2/ (probably the latter); from Quarry II, Tsagan-Khushu.

This isolated tooth is much larger than those of the insectivores described above and breakage coupled with
its disassociated state has hindered its analysis.

PSS 20-95 (text-fig. 9a) is little worn and moderate in transverse elongation with respect to its anteroposterior
diameter. The summit of the paracone is broken but it was probably higher than the metacone. The two cusps
are joined at their base, but, from the lingual base of the metacone, they are connate only to about midway
on this cusp. Both paracone and metacone are relatively low and support strong anterior and posterior crests,
the former extending to the parastyle and the latter to the metastyle. There is no notch in this metastylar wing
separating it from the metacone; an elongage wear facet, extending along its length and pinching out near the
summit of the metacone, indicates its use as a shearing surface. The metacone, in fact, is compressed labio-
lingually; it is oriented sub-vertically. The paracone is more inflated and slopes more abruptly labially. A
moderately wide labial shelf exists labial to the metacone but it was probably very reduced opposite the
paracone (the area is broken away). The metastyle is directed posteriorly and not at all labially. Little can be
said of the shape of the parastyle, except that it probably did not extend farther anteriorly beyond its present
state. The paraconule is higher, bigger, and more lingually situated than the metaconule; the preparaconular
crest connects with the tip of the parastyle; a postparaconular crest is absent and there is no linkage with the
paracone. The metaconule is more crestiform and possesses a strong premetaconular crest that is directed
anterolabially to the lingual groove separating the bases of the paracone and metacone. The postmetaconular
crest is strongly developed and extends to below the posterior side of the metacone; it does not follow the
base of the metastylar wing. Loss of the protocone area is unfortunate. The anterior cingulum is slight and
reaches to below the front of the paraconule. A hypoconal shelf and a strong hypocone are developed
posteriorly. The tooth is moderately indented posteriorly at the end of the hypoconal shelf, and anteriorly
about midway between the paraconule and the parastyle.

Measurements.

Length Width
PSS 20-95: M2/? 4-9 est. 6 0 est.

RUSSELL AND DASHZEVEG: EOCENE INSECTIVORES FROM MONGOLIA

287

Comparisons. In view of the incomplete nature of the tooth, identification can only be approximate.
However, PSS 20-95 is of comparable size to North American Palaeosinopa and displays a mor-
phology that is significantly similar. Gingerich (1980) pointed out that the two principal differences
separating the late Palaeocene Palaeotomus from the late Palaeocene species of Palaeosinopa (P.
dorri ) lay in the greater anteroposterior width of the lingual part of M 1 / in Palaeosinopa and a
more labial position of the hypocone. These features in PSS 20-95 show a probable resemblance
(the area is damaged) to Palaeosinopa in hypocone position and a lingual width that is about
intermediate between the two. These observations suggest a closer affinity to Palaeosinopa than to
Palaeotomus , which is also consistent with the age of Tsagan-Khushu; apart from Palaeosinopa
dorri , Palaeosinopa is a typical early Eocene form.

PSS 20-95 is longer anteroposteriorly than the comparable tooth of P. dorri (metastylar develop-
ment especially is greater), but is less elongate transversely. The known teeth of P. dorri are in an
advanced stage of wear and it is not possible to compare paracone and metacone formation. The
labial cingulum, however, is more marked and there seems to be no sharp premetaconular crista in
the P. dorri M2/. Wasatchian material referred to Palaeosinopa is extremely variable as regards
details. In specimens referred to P. veterrima, for example, the hypocone is strong on one specimen
and absent on another; the premetaconular and postmetaconular crests are sharp and well defined
on one and vague or absent on another; stylar and cingular development is also variable. In other
specimens the paraconule is weaker than the metaconule, instead of the reverse, and the lingual
width of a given tooth varies. This situation negates excessive reliance on particular details and
renders necessary considerable caution when working with incomplete or inadequate samples. It is
nevertheless possible to say that the basic morphology of PSS 20-95 resembles that of Palaeosinopa
more than that of any other genus known to us.

In Europe the upper teeth of P. osborni , from the Ypresian of France, have not yet been studied,
the later Eocene Cryptopithecus and Dyspterna are quite different and the middle Eocene Buxolestes
lacks any development of a shearing metastyle; but Pagonomus (late Palaeocene) shows a metastylar
flare quite similar to that of PSS 20-95. However, the paracone and metacone are less connate and
the tooth of less massive aspect.

The diminutive pantolestid from the late Palaeocene of North America, Bessoecetor (or Pro-
palaeosinopa ), should be cited for the size and shape of its upper molar metastyle, thereby constitut-
ing another link between PSS 20-95 and this group. It is not as similar as Pagonomus , however.

The wide flaring of the metastyle in PSS 20-95, more than in typical Palaeosinopa , might indicate
a generic difference, as might the basally connate paracone and metacone. But the latter are found
to an even greater degree in a specimen from Bear Creek (AMNH 22221), referred to P. cf.
didelphoides. For the moment, it is not possible to go further than a designation of Pantolestidae
gen. indet. for PSS 20-95, while keeping in mind an intriguing similarity with Pagonomus and an
affinity with Palaeosinopa.

An isolated left lower M/3, PSS 20-128 (text-fig. 9 g, h), from Quarry I might be referable to the
same taxon as PSS 20-95. It is of comparable size; the trigonid is moderately high and supports a
well excavated trigon basin. The paraconid is large, high, and crestiform and is separated from the
anterior protoconid crest by a deep notch; another notch occurs between the median crests of the
protoconid and metaconid. The latter is only slightly higher than the paraconid, while the protoconid
is by far the highest cusp. Vertically, along its posterolingual border, the metaconid is inflated into
a rounded ridge. The talonid is of moderate proportions (approximately the same length as the
trigonid); the hypoconid is the highest cusp and forms a strong V labially in occlusal view. The
hypoconulid is a cusp nearly as big, projecting posteriorly. By far the smallest of the three talonid
cusps is the entoconid, crestiform and situated opposite the hypoconid. The anterior crest of the
entoconid is parallel to the cristid obliqua and both are oriented posterolabially. The cristid obliqua
contacts the posterior trigonid wall below the notch.

Following the apparent affinity deduced for the upper molar, PSS 20-95, the relationships of PSS
20-128 also appear to lie within the Pantolestidae. Comparison with specimens of Palaeosinopa
from Bitter Creek, Wyoming, and of P. incerta , both Wasatchian, shows a particular similarity (see

288

PALAEONTOLOGY, VOLUME 29

text-fig. 9. a , Pantolestidae gen. indet., PSS 20-95, right Ml/ or M2/, occlusal view, x 10-5. b and c,
Nyctitheriidae gen. indet., PSS 20-70, partial left M/1 or M/2; b , lingual view; c, occlusal view, x 15. d and
e , cf. Hyracolestes sp., PSS 20-124. left M/1 or M/2; d , occlusal view; e, lingual view, x 1 5. /, Nyctitheriidae
gen. indet., PSS 20-60, right Ml/, occlusal view, x 15. g and /;, Pantolestidae gen. indet., PSS 20-128, left
M/3; g, lingual view; /?, occlusal view, x 10. All specimens are from Tsagan-Khushu, Naran-Bulak Forma-
tion, Bumban Member, MPR, and are housed in the Institute of Geology, Ulan Bator.

Sown and Schankler (1982) for an excellent discussion of the latter and other early insectivores).
Minor differences include: the talonid cristid obliqua and the anterior crest of the entoconid are
oriented less posterolabially, the talonid basin is a little wider, the metaconid has less of a vertical
bulge posteriorly, and the paraconid is smaller.

In some creodonts the trigonid cusps have a similar aspect, although they tend to be more inflated.
Usually the cristid obliqua is directed more anteroposteriorly, the hypoconid does not project
labially and forms a massive crest, the talonid basin is deeper, and the region containing the
entoconid and hypoconulid is diversely modified but in no way closely resembles that seen in PSS
20-128. The supposition that this tooth belongs to the same taxon as PSS 20-95 is supported by the
evidence available, but proof, of course, is lacking.

Another isolated lower molar, PSS 20-63, entirely lacks enamel. It appears to have had a mor-
phology similar to that of PSS 20-128 described above, but nothing of decisive value can be deduced
from it.

RUSSELL AND DASHZEVEG: EOCENE INSECTIVORES FROM MONGOLIA

289

Order indet.

Family indet.
cf. Hvracolesties sp.

Text-fig. 9 d, e

Material. PSS 20-124, isolated left lower M/1 or M/2, from Quarry I, Tsagan-Khushu.

This tooth (text-fig. 9 d, e), excellently preserved, represents an animal with a largely carnivorous diet. The
trigonid is high with a wide, lingually open basin. The paraconid is large, high, and crestiform and is separated
from the anterior crest of the protoconid by a marked notch. A vertical crest occurs at its most anterior point.
The protconid is by far the highest of the trigonid cusps and slopes dorsolingually so that (in posterior view)
its tip is situated in line with the hypoconulid. The metaconid is well below the protoconid but is higher than
the paraconid. A notch occurs at the midline between the median crests of the metaconid and protoconid. A
strong anterocingulum crosses obliquely the base of the protoconid and extends posteriorly on the lingual
base of the cusp. The talonid is narrow but nearly as long as the trigonid. While constituting the principal
talonid cusp the hypoconid is small with little labial projection; the cristid obliqua is only moderately oriented
anterolingually and contacts the posterior wall of the trigonid well below the notch. The hypoconulid is large,
nearly as big as the hypoconid and is as high. The entoconid is a little lower, is situated slightly posterior with
respect to the hypoconid, and is crestiform. Its anterior crest (parallel the cristid obliqua) closes the deep
talonid basin except just behind the metaconid. A strong posterocingulum extends from the tip of the
hypoconulid labially to below the hypoconid, forms a sharp angulation (in occlusal view) at the posterolabial
corner of the tooth, and nearly meets the posterior extension of the anterocingulum.

Measurements. Length Width

PSS 20-124: M/1 or M/2 2-6 1-5

Comparisons. PSS 20-124 is close in size to Bumbanius rams but it differs markedly by its narrower
talonid, by its higher paraconid, and the presence of a notch between the latter and the protoconid.
It is quite different from the other insectivores known at Tsagan-Khushu.

The carnivorous aspect of the tooth prompted comparison first of all with the Hyaenodontidae,
but talonid details are unlike any seen in that group. The M/1 of miacids was also examined.
Usually the trigonid in these forms is lower and more inflated. The talonid is usually shorter and
the size and disposition of the talonid cusps is different. Simpsonictis tenuis (middle Palaeocene,
North America) is the closest in morphology, but its talonid is distinctly wider. A labial cingulum
is present, however, as in PSS 20-124.

While certainly not identical the M/1 of Hyracolestes ermineus bears some resemblance to PSS
20-124. Unlike the preceding forms it is about the same size. The trigonid cusps are of similar
proportions, although the protoconid is less inflated lingually and does not seem to slope dorsolingu-
ally (but the summit of the cusp is lacking in the holotype). The talonid is also of similar proportions
but the hypoconid has been broken off and the entoconid worn off, which inhibits a precise
comparison. No cingula are present on the holotype of Hyracolestes ; even the presence of an
anterocingulum is unsure as the area is worn. A referred specimen of Hyracolestes from the upper
part of the Doumu Formation (Qianshan Basin, Anhui Province, China) is poorly preserved and
shows little that is not indicated on the type. The remains of an anterocingulum occur, however.

The relationships of PSS 20-124 are far from clear. For the moment it is not possible to refer it
to either a family or to a known genus. There is a possibility that it might be related to Hyracolestes ,
but more complete material of both are needed. Except for the resemblance seen in Simpsonictis it
is not likely that PSS 20-124 is related to the Miacidae and it surely bears no affinity to the
Hyaenodontidae.

CONCLUSIONS

For the most part relatively minor details separate Bumbanius and Leptacocion , although differences
indicating generic distinction do exist (entoconid and hypoconulid size and relations, in particular).
Excepting, principally, the placement of the paraconid in the known teeth of Praolestes , there is

290

PALAEONTOLOGY, VOLUME 29

sufficient similarity between it and Bumbanius to suspect the existence of a common relationship
within the Nyctitheriidae.

Oedolius shows a closer relationship to Bumbanius than to any other known genus and the two
together suggest the presence in Asia of a group that is still undefined. Additional material may
someday provide evidence for new suprageneric taxa to include the slowly accruing material and
knowledge of Asiatic insectivores, but for the moment we will content ourselves with assignment of
Bumbanius and Oedolius to the Nyctitheriidae.

Two specimens (PSS 20-62 and PSS 20-60), consisting of upper teeth, testify to the diversity of
lipotyphlan insectivores in the Tsagan-Khushu fauna, but they have been left unnamed.

The greatest similarity to Naranius among existing taxa is to be found among the late Cretaceous
Palaeoryctidae of North America, Procerberus and Batodon , in particular. Whether or not these,
or closely related genera, inhabited Asia in the Cretaceous is not yet demonstrated. It would appear,
however, that Naranius is a primitive, relatively low-crowned descendant of stock that was dentally
closely similar to them. Given the lack of evidence from the Palaeocene of Asia it is not possible to
speculate profitably on the point of origin of Naranius' s ancestors. The same must be said for
Tsaganius, with even more emphasis on the apparent relationship it shares with Batodon.

The pantolestid specimen, from what can be deduced of its morphology, suggests affinity with
late Palaeocene and Eocene North American and European forms.

In summary, it should be noted that the new insectivores from the early Eocene of Mongolia do
not show signs of particularly strong endemism. Quite the contrary, they uniformly indicate a
relationship to North American late Cretaceous or late Palaeocene forms. To what extent this
translates the intercontinental exchange that produced the appearance of Wasatchian/Ypresian
Holarctic genera such as Hyracotherium and Hyopsodus , or how much is due to previous exchange
cannot yet be determined. Whatever the moment of dispersal, it is clear to us that the taxa described
here are rather closely related to others in North America and Europe and did not develop in
isolation.

The principal aim of these descriptions is to put the taxa on record and available for discussion.
It is too early for a coherent taxonomy of the Eocene insectivores of Asia.

Acknowledgements. The authors would like to express their appreciation to Dr T. M. Brown and Professor
P. D. Gingerich for having read the manuscript and considerably improved it by their judicious remarks.
Dr P. M. Butler examined the specimens after the manuscript was written and kindly sent extensive comments.
Our conclusions are, for the most part, concordant. The figures were drawn by Mesdemoiselles J. Crapart
and S. Vrain, the SEM photos taken by Madame C. Weber, and the manuscript typed by Madame S. Guignes.

REFERENCES

bown, t. m. and schankler, d. 1982. A Review of the Proteutheria and Insectivora of the Willwood Formation
(lower Eocene), Bighorn Basin, Wyoming. Geol. Surv. Bull. 1523, i-iv, 1-79.
cappetta, h., jaeger, j. j., Sabatier, m., siGE, b., sudre, j. and vianey-liaud, m. 1978. Decouverte dans le
Paleocene du Maroc des plus anciens mammiferes eutheriens d’Afrique. Geobios , 1 1 (2), 257-262.
dashzeveg, d. 1976. Novyye mezonikhidy (Condylarthra, Mesonychidae) iz paleogena Mongolii (New
mesonychids (Condylarthra, Mesonychidae) from the Palaeogene of Mongolia). In Kramarenko, n. n.
(ed.). Paleontologiya i biostratigrafiya Mongolii , Sovmestnaya Sov. — Mong. Paleont. Eksped. 3, 14-31.
[In Russian ]

1977. O pervoy nakhodye Hyopsodus Leidy, 1870 (Mammalia, Condylarthra) v Mongol' skoy Narodnoy
Respubliye (On the first occurrence of Hyopsodus Leidy, 1870 (Mammalia, Condylarthra) in the People’s
Republic of Mongolia). In barsbold, r (ed.). Fauna, flora i biostratigrafiya mezozoya i kaynozoya Mongolii.
Sovmestnaya Sov. — Mong. Nauchno-Issled. Geol. Eksped. 4, 7-13 [In Russian.]

1979 a. Nakhodka girakoteriya v Mongolii (Discovery of a hyracothere in Mongolia). Paleontol. Zh. 3,
108 1 13. [In Russian].

— 19796. Nakhodka ITomogalax (Perrisodactyla, Tapiroidea) v Mongolii i ego stratigraficheskoye znach-
eniye (A find of Homogalax (Perissodactyla, Tapiroidea) in Mongolia and its stratigraphic significance).
Byulletin Moskovskogo Obshchestva Ispytateley Prirody , Otdel Geol. 54 (6), 105-1 1 1 . [In Russian.]

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1982. La faune de Mammiferes du Paleocene inferieur de Naran-Bulak (Asie Centrale) et ses correlations
avec l’Europe et FAmerique du Nord. Bull. Soc. Geol. Fr. (7), 24 (2), 275-281.

— and mckenna, m. c. 1977. Tarsioid Primate from the early Tertiary of the Mongolian People's Republic.
Ada. Palaeont. Polonica, 22 (2), 1 19-137.

gingerich, p. d. 1980. A new species of Palaeosinopa (Insectivora; Pantolestidae) from the late Paleocene of
Western North America. J. Mamm. 61 (3), 449-454.

— 1982. Aaptoryctes (Palaeoryctidae) and Thelysia (Palaeoryctidae?): new insectivorous mammals from the
late Paleocene and early Eocene of Western North America. Contrib. Mas. Paleont ., Univ. Michigan. 26 (3),
37-47.

gradzinski, r., KAZMiERCZAK, j and lefeld, j. 1969. Geographical and geological data from the Polish-
Mongolian Palaeontological Expeditions. Results Polish Mongol. Palaeont. Exped. I. Palaeont. Pal 19,
33-82.

krishtalka, L. and west, R. m. 1979. Paleontology and geology of the Bridger Formation, southern Green
River Basin, southwestern Wyoming, Part 4. The Geolabididae (Mammalia, Insectivora). Contrib. Biol.
Geol., Milwaukee Pub. Mus. 27, 1-10.

novacek, m. j. 1976. Insectivora and Proteutheria of the later Eocene (Uintan) of San Diego County,
California. Contrib. 5c/., Nat. Hist. Mus., Los Angeles Co. 283, 1 -52.
szalay, f. s. and mckenna, m. c. 1971. Beginning of the age of mammals in Asia: the late Paleocene Gashato
fauna, Mongolia. Amer. Mus. Natur. Hist., Bull. 144 (4), 269-318.

D. E. RUSSELL
Institut de Paleontologie
UA 12CNRS
8, rue Buffon
75005 Paris, France

Typescript received 25 January 1985
Revised typescript received 22 July 1985

D. DASHZEVEG

Institute of Geology
Academy of Sciences
Ulan Bator,

Mongolian People’s Republic

THE LATE TRIASSIC REPTILE
TERATOSAURUS^ A RAUISUCHIAN,
NOT A DINOSAUR

by MICHAEL J. BENTON

Abstract. Teratosaurus, based on a maxilla from the late Triassic of Germany, is shown to have been a
rauisuchian, and not a dinosaur. The Family Teratosauridae, based on skull remains and skeletons from
around the world, is not an early radiation of carnivorous dinosaurs: it consists of the skeletons of
prosauropod dinosaurs and the skulls and teeth of rauisuchians, or unidentifiable archosaurs. Other records
of middle Triassic dinosaurs are also suspect. The Rauisuchia was a widespread and important group of large
carnivores in the middle and late Triassic, and they had no close relationship with any dinosaurs.

According to most current classifications of the dinosaurs, there was an extensive group of large
carnivorous forms present in the middle and late Triassic (240-208 Ma), variously named
Teratosauridae, Palaeosauridae, Zanclodontidae, or Gryponychidae (Romer 1956; Colbert 1964;
Charig et al. 1965; Olshevsky 1978; Lambert 1983). Colbert (1970) elevated this assemblage to the
Infraorder Teratosauria. This group has been viewed as an early major radiation of carnivorous
dinosaurs that did not bear a close relationship to the typical Jurassic and Cretaceous carnosaurs.
The genus Teratosaurus was established in 1861 (Meyer 1861) on the basis of a maxilla bearing
large dagger-like teeth. Subsequently, further isolated carnivorous teeth and partial jaws, as well as
large amounts of postcranial material, were associated with this genus. I show here that the type
jaw of Teratosaurus belongs to a rauisuchian, a group of thecodontians that were distributed
world-wide in the middle and late Triassic. The skeletons belong to a different group the
prosauropod dinosaurs (Walker 1964; Charig et al. 1965).

Teratosaurus suevicus Meyer, 1861
Type specimen. British Museum (Natural History), BMNH 38646
First description. Meyer 1861 : 258-271, pi. 45.

Locality. Heslach, near Stuttgart (Strobel and Wurm 1977) ‘on the other side of the valley' from the site of
an earlier dinosaur find (Meyer 1861). Possibly the old quarry centred at 3510554007 (map sheet 7220), labelled
‘Stbr.’ (Steinbruch, quarry); now filled and used as a Sportplatz.

Age. Mittlerer Stubensandstein, Mittelkeuper, Middle Norian, Upper Triassic (Brenner 1973).

The specimen (text-fig. 1 ) is a right maxilla (Walker 1964), not a left one, as was originally assumed
(Meyer 1861; Huene 1908). The specimen measures 235 mm long (or 245 mm with a small additional
piece at the front). In lateral view (text-fig. la), the remains of six teeth (2-7) may be seen. A
detached flake of bone (not shown here) fits over the first two teeth, and it contains a third small
tooth (1) in front of them. In medial view (text-fig. 16), five teeth are seen below the edge of the
jaw. At the front of the maxilla is a ledge which covers a deep socket (ps) for reception of the
premaxilla. There are various pits (v?) on the inside of the maxilla which may be blood vessel
and/or nerve openings. The most interesting area is the tooth-bearing portion. On the inside of the
maxilla (text-fig. 16) can be seen an apron or pedestal that overlies the teeth. There is a line of holes
(rp), one for each tooth, and the bone below is characterized by small pits, 1 mm in diameter. The

| Palaeontology, Vol. 29, Part 2, 1986, pp. 293-301. |

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PALAEONTOLOGY, VOLUME 29

text-fig. 1. Teratosaurus suevicus, type specimen, BMNH 38646. Left maxilla, a ,
lateral view; b , medial view. The surface of the bone is much cracked and it has
been repaired with glue, and coated with thick varnish in places. The upper
portion (stippled) is partly unprepared- it consists of whitish-grey sandstone and
glue. The teeth and tooth-sockets are numbered 113 from the front. ANT,
anterior; ps, socket for the premaxilla; rp, tooth replacement pit; s, the serrated
zones of the anterior and posterior tooth edges; v?, blood vessel or nerve opening (?).

BENTON: TERATOSAURUS

295

lateral edge of the maxilla comes lower than this medial ledge, and it is visible in medial view. The
holes are replacement pits through which new tooth buds passed from the medially lying dental
lamina to become fixed in the bone of the jaw. The pitted bone appears to be highly vascular and
was probably constantly remodelled as new teeth passed through it, and the teeth grew into
occlusion. The lower edge of the medial apron is scalloped at the midline of each tooth.

Seven teeth are preserved in one form or another in this specimen in the anterior sockets (1-7).
The posterior six sockets (8-13) have no teeth in them. There appears to be some sort of variation
in tooth size: 1, 2, 4, and 7 are small and barely erupted, 6 is a little larger, and 3 and 5 are the
largest. The roots of full-sized teeth are very long, 50-60 mm for a crown length of 40-50 mm. In
cross-section the teeth are oval and laterally compressed at the level of the jaw margin, and their
long axes run from anteromedial to posterolateral. Just below the jaw edge the posterior margin of
the tooth becomes pinched into a sharp knife-like edge with 3 serrations per mm. The front edge of
the tooth remains rounded down to a slight ‘shoulder’ half-way down the crown (text-fig. 1 a, s),
where this edge also becomes sharp and serrated.

DISCUSSION

Teratosaurus a rauisuchid

The teeth described here (BMNH 38646) are indistinguishable from those of typical rauisuchids
such as Rauisuchus and Prestosuchus (Huene 1935-1942) (specimens in the Bayerische Staats-
sammlung fur Palaontologie und historische Geologie, Miinchen). The maxilla is virtually identical
in shape with that of other rauisuchians such as Ticinosuchus (Krebs 1965), Saurosuchus (Sill 1974),
Heptasuchus (Dawley et cd. 1979), and a new undescribed rauisuchid from SW Germany (R. Wild,
pers. comm., specimens in Staatliches Museum fur Naturkunde in Stuttgart, SMNS). This specimen
shows two synapomorphies of the Rauisuchia: evidence of a movable joint between the maxilla
and premaxilla, and a supplementary fenestra between maxilla and premaxilla (Benton 1 984<r/)
Within the Rauisuchia, Teratosaurus may be a rauisuchid (Bonaparte 1981; Galton 1985) or a
poposaurid (Chatterjee 1985).

After 1861 many more fossil remains from the middle and late Triassic of Germany were
assigned to Teratosaurus : teeth and skeletons (Huene 1908, 1915, 1932). Several authors (Colbert
1964; Walker 1964; Charig el al. 1965) have noted that the skeletons are very like those of
prosauropod dinosaurs such as P/ateosaurus, and they placed the Teratosauridae in the Prosauro-
poda (Palaeopoda: Colbert 1964) or left them as ‘Saurischia incertae sedis' (Charig et al. 1965).
However, there is no evidence for association of any of the skeletons with the teeth (Charig et al.
1965). It is likely that all ‘ Teratosaurus ’ skeletons belong to true prosauropods such as Plateosaurus ,
and that all Teratosaurus teeth belong to rauisuchids, or are indeterminate. Teratosaurus teeth are
known from the Unterer and Mittlerer Stubensandstein of numerous localities in Baden-
Wiirttemberg (specimens in the Stuttgart and Tubingen collections). Teeth named as Teratosaurus
have also been described from the middle Triassic of Germany (Fraas 1900) and England (Huxley
1870), but they cannot be identified to generic level.

Other Triassic ‘ carnosaurs'

The genera other than Teratosaurus that have been called middle to late Triassic or early Jurassic
carnosaurs include such forms as Palaeosaurus and Cladeiodon from England, Palaeosaurus ,
Zanclodon , and Gresslyosaurus from Germany, Orosaurus, Aetonyx , and Gryponyx from South
Africa, Zatomus from North America, and Sinosaurus from China (Romer 1956). The type
specimens of Palaeosaurus and Cladeiodon from England, and Zatomus , are teeth and, as such,
they cannot be assigned with certainty to a particular group of dinosaurs or thecodontians: they
are effectively indeterminate (Charig et cd. 1965). Palaeosaurus from Germany is an anchisaurid
prosauropod renamed Efraasia (Galton 1973). The type specimens of the several species of
Zanclodon are teeth, again indeterminate. Gresslyosaurus is a large prosauropod dinosaur, and
Orosaurus has been synonymized with the large prosauropod Euskelosaurus (Van Heerden 1979).

296

PALAEONTOLOGY, VOLUME 29

Aetonyx and Gryponyx are also prosauropod dinosaurs, probably identical to Massospondylus
(Galton and Cluver 1976). Sinosaurus was based on a maxilla with teeth (dinosaur or thecodontian?)
and postcranial remains very like those of a melanorosaurid prosauropod (Charig et al. 1965). This
leaves no convincing evidence of large carnivorous dinosaurs in the Triassic.

Other doubtful early dinosaurs

Many other remains of early ‘dinosaurs' have been described from the middle and late Triassic of
Germany in particular, and these have given the impression of a long early evolution of the group.
In reviews of Triassic dinosaurs, Huene (1914u, 1932) noted the following earliest forms, listed here
in stratigraphic order:

Lower Muschelkalk (Anisian): Thecodontosaurus primus , Zanclodon silesiacus, Tanystropheus
antiquus , unnamed coelurosaur ‘femora’ (Huene 19146).

Upper Muschelkalk (Ladinian): Tanystropheus conspicuus, Procerosaurus cruralis, Teratosaurus
schuetzii, Thecodontosaurus latespinatus.

Lettenkeuper (Upper Ladinian): Zanclodon laevis , Zanclodon crenatus , Avipes dillestedtianus, and
two ‘typical coelurosaur teeth’ (Huene 1932).

Schilfsandstein (Carnian): Thecodontosaurus subcylindrodon.

70° N

0(

19,20/

11,12*

2 1,24,28

70° S

text-kig. 2. The distribution of rauisucliians plotted on a palaeogeographic map for the Triassic (Cox 1974).
The modern continental outlines are shown with dashed lines, and the outlines of the Triassic supercontinent
Pangaea are shown with a solid line. • = Lower and Middle Triassic rauisuchians. a = Upper Triassic
rauisuchians. The numbers correspond to the twenty-nine genera of rauisuchians listed in Table 1.

BENTON: TERATOSAURUS

297

Most of these species were based on single teeth or isolated damaged bones. Nevertheless, it now
seems clear that none of these specimens is dinosaurian. Those named as T any strophe us,
Procerosaurus , Thecodontosaurus latespinatus , and Z. laevis belong to the prolacertiform Tanystro-
pheus (Wild 1973). The other species of Zanclodon , Thecodontosaurus , and Teratosaurus noted
above, as well as the ‘coelurosaur teeth’, are based on single teeth which could be prolacertiform or
thecodontian. Avipes is based on a bundle of three incomplete ‘metatarsals’. If that anatomical
interpretation is correct, and this is not certain, they do not have any diagnostic characters of a
dinosaur. The Lower Muschelkalk ‘coelurosaur femora’ (Huene 1914 b) seem to be more like the
distal ends of two humeri of a placodont such as Cyamodus (pers. obs.)!

The Rauisuchia

The Rauisuchia includes several reptiles from the middle and late Triassic (Table 1; text-figs. 2, 3).
These are characterized by the following features (Krebs 1976; Benton 1984c; Benton and Norman
1986):

1. Extra slit-like antorbital fenestra between premaxilla and maxilla.

2. Movable joint between maxilla and premaxilla.

3. Main antorbital fenestra is low in front.

4. Tall orbit with a ‘stepped’ postorbital/jugal bar behind.

5. Lacrimal forms a heavy ‘eyebrow ridge’ over the orbit.

6. Centra of dorsal vertebrae are very constricted in ventral view.

7. Reduced contact between pubis and ischium.

text-fig. 3. The skulls of some rauisuchids drawn to unit length. These are all reconstructions since no
complete rauisuchid skull is known. The maxilla of Teratosaurus is shown (reversed) for comparison, a ,
Ticinosuchus (Krebs 1965); b , Luperosuchus (Romer 1971); c, Heptasuchus (Dawley et at. 1979); d ', Saurosuchus
(Sill 1974; Bonaparte 1981); e, Teratosaurus , BMNH 38646. The scale bars are 50 mm long. Note that
Ticinosuchus (a) may have had the typical rauisuchid narrow fenestra between maxilla and premaxilla (Sill 1974).

298

PALAEONTOLOGY, VOLUME 29

table 1. The genera of rauisuchians (Krebs 1976; Galton 1977; Bonaparte 1981, 1984; Chatterjee 1985)
arranged in stratigraphic sequence (Oslen el at. 1982; Tucker and Benton 1982).

LOWER TRIASSIC
Scythian (Spathian)

1 . ? Wangisuchus, Er-Ma-Ying Series, China.

2. IFenhosuchus, Er-Ma-Ying Series, China.

MIDDLE TRIASSIC
Anisian

3. ‘ rauisuchid Yerrapalli Formation, India.

4. Vjushkovisaurus , Donguz Series, Orenburg Region, USSR (Ochev 1982).

5. Stagonosuchus , Manda Formation, Tanzania.

6. ‘ Mandasuchus\ Manda Formation, Tanzania.

Anisian/Ladinian

7. Ticinosuchus, Grenzbitumenhorizont, Switzerland.

8. 1 Ticinosuchus ’, Grenzbitumenhorizont equivalent, Besano, North Italy (Pinna and Arduini

1978).

9. ‘ Ticinosuchus ’, Fissure fillings, Gliny, Poland.

Ladinian

10. ‘ poposaurid ’, Broinsgrove Sandstone Formation, England.

1 1. lArizonasaurus , Holbrook Member, Arizona, USA.

12. ‘ Anisodontosaurus' , Holbrook Member, Arizona, USA.

13. Luperosuchus, Chanares Formation Argentina.

14. ‘ Teratosaurus \ Lettenkeuper, South West Germany (Fraas 1900).

15. undescribed form, Lettenkeuper, South West Germany (Wild 1980).

UPPER TRIASSIC

Middle-Upper Carnian

16. Rauisuchus, Santa Maria Formation, Brazil.

17. Prestosuchus , Santa Maria Formation, Brazil.

18. IProcerosuchus , Santa Maria Formation, Brazil.

19. Poposaurus, Popo Agie Formation, Wyoming, USA.

20. Heptasuchus, Popo Agie Formation, Wyoming, USA.

21. 'rauisuchid', Chinle Formation, Arizona, USA.

22. 'rauisuchid'. Lower Wolfville Formation, Nova Scotia, Canada.

23. 'rauisuchid', Argana Formation, Argana, Morocco (Dutuit 1979).

24. unnamed forms, Dockum Formation, Texas, USA.

25. Saurosuchus, Ischigualasto Formation, Argentina.

Upper Carnian-Lower Norianf?)

26. 'rauisuchid'. Lower Elliot Formation, South Africa (Galton 1985).

Middle Norian

27. Teratosaurus , Stubensandstein, South West Germany.

28. Postosuchus , (Upper) Dockum Formation, Texas, USA (Chatterjee 1985).

Upper Norian-'Rhaetian'

29. ? Fasolasuchus , Upper Los Colorados Formation, Argentina.

8. Pubis attaches to an anteroventral facet on the ilium, rather than a ventral one.

9. Pubis has a distal ‘foot’ which is small in rauisuchids, but large in poposaurids.

The Rauisuchia contains two families, the Rauisuchidae and the Poposauridae which are
distinguished from each other on the basis of characters of the skull and limbs (Chatterjee 1985). It
is not possible at present to decide whether Teratosaurus was a rauisuchid or a poposaurid.
Poposaurids may have been facultatively bipedal, and rauisuchids were large, 2-5 m long
quadrupeds. They were powerful meat-eaters, and probably the top carnivores in their respective

BENTON: TERATOSAU RUS

299

faunas. The Rauisuchia ranged in age from the latest Scythian to the Norian (latest early Triassic
to late Triassic) (Table 1), and they radiated virtually world-wide during that time: rauisuchians
are known from all continents except Australia and Antarctica (text-fig. 3). The Rauisuchia clearly
fall within a group containing the phytosaurs, crocodiles, and aetosaurs— these all have the
‘crocodile-normal’ tarsus in which the astragalus forms a distal peg which fits into a' deep socket on
the calcaneum, and the two elements can rotate about his joint (Krebs 1976; Chatterjee 1982).
Further, the Rauisuchia show close affinities with the Aetosauria, a late Triassic group of
herbivorous archosaurs (Benton 19846). All of these forms (termed the Pseudosuchia) share several
synapomorphies in comparison with crocodiles and phytosaurs:

1. Frontal bone extends well forward and lies mainly in front of the orbits.

2. Iliac blade is oriented subhorizontally, rather than vertically.

3. Proximal distance between the ischia is less than that between the pubes.

4. Acetabulum is horizontal and faces downwards so that the femur fits directly into it. This
gives all pseudosuchians a kind of erect gait that differs from the erect gait of dinosaurs, birds, and
some early crocodile-like animals (Benton 1984a; Bonaparte 1984; Parrish 1984).

The Dinosauria

The Pseudosuchia, including the rauisuchians, probably did not have any close relationship with
the dinosaurs at all. The pseudosuchians and crocodiles form a completely separate evolutionary
line from the dinosaurs, and their allies.

Until recently, and with only a few exceptions (e.g. Bakker and Galton 1974; Bonaparte 1976),
the dinosaurs were thought to have evolved as several separate lineages that derived from ancestors
in the middle Triassic, or earlier. However, a remarkable consensus of opinion has now been
reached that the dinosaurs are a monophyletic group by several workers who have independently
carried out cladistic analyses of the archosaurs (Benton 1984c; Norman 1984; Parrish 1984; Paul
1984; Sereno 1984; reviewed, Benton 19846). The closest sister-groups of the Dinosauria are
Lagosuchus , the Ornithosuchidae and, controversially, the Pterosauria (Padian 1984).

In conclusion, there is no evidence for an early radiation of large carnivorous dinosaurs in the
Triassic. The ‘Teratosauria’ has been shown to be an unnatural assemblage of prosauropod
skeletons, rauisuchian jaws, and unidentifiable teeth. The earliest dinosaurs were rare medium
sized and small primitive forms and theropods from the late Triassic (middle-late Carnian) of the
USA, Brazil, Argentina, Scotland, and India. A number of important reptile groups — rhynchosaurs,
and many lineages of mammal-like reptiles and thecodontians— died out at the end of the Carnian
(Benton 1986), and the theropods and prosauropods radiated subsequently in the Norian (Benton
1983). The rauisuchians, and other remaining thecodontians died out at the end of the Triassic,
and the theropods and the prosauropods continued to radiate in the early Jurassic, together with
the ornithopods. The first large carnivorous theropod dinosaurs (‘carnosaurs’), appeared in the
early and middle Jurassic.

Acknowledgements. I thank Rupert Wild for information about the new German rauisuchian, and A. R. I.
Cruickshank, T. S. Kemp, D. B. Norman, and A. D. Walker for helpful comments on the manuscript.

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krebs, b. 1965. Die Triasfauna der Tessiner Kalkalpen. XIX. Ticinosuchus ferox nov. gen. nov. sp. Schweiz.
Palaontol. Abh. 81, 1-140.

- - 1976. Pseudosuchia. Handb. Palaoherpetol. 13, 40-98.

Lambert, D. 1983. Collins Guide to Dinosaurs, 256 pp. Collins, London.

meyer, H. von. 1861. Reptilien aus dem Stubensandstein des oberen Keupers. Palaeontographica, 7, 253-346.
norman, d. b. 1984. A systematic reappraisal of the reptile order Ornithischia. In reif, w.-e. and westphal, f.
(eds.). Third Symposium on Mesozoic Terrestrial Ecosystems, Tubingen 1984 , Short Papers, 157-162.
Attempto, Tubingen.

ochev, v. G. 1982. Pseudosuchia from the Middle Triassic of the southern Ural forelands. Paleontol. J. 1982,
95-101.

olsen, p. e., mccune, a. and Thomson, k. s. 1982. Correlation of the Early Mesozoic Newark Supergroup by
vertebrates, principally fishes. Am. J. Sci. 282, 1 -44.

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301

Olshevsky, G. 1978. The Archosaurian Taxa, 50 pp. G. & T. Enterprises, Toronto.
padian, k. 1984. A functional analysis of flying and walking in pterosaurs. Paleobiology , 9, 218-239.
parrish, j. m. 1984. Locomotor grades in the Thecodontia. In reif, w.-e. and westphal, f. (eds. ). Third
Symposium on Mesozoic Terrestrial Ecosystems, Tubingen 1984 , Short Papers , 169 I 73. Attempto, Tubingen.
paul, G. s. 1984. The archosaurs: a phylogenetic study. In reif, w.-e. and westphal, f. (eds.). Ibid. 175-180.
Attempto, Tubingen.

pinna, g. and arduini, p. 1978. Un nuovo esemplare di Ticinosuchus ferox Krebs, rinvenuto nel giacimento
Triassico di Besano in Lombardia. Natura , Soc. ital. Sci. nat., Mas. civ. Stor. nat. Acquar. civ. Milano , 69,
73-80.

romer, a. s. 1956. Osteology of the Reptiles , 772 pp. University of Chicago, Chicago.

1971. The Chanares (Argentina) Triassic reptile fauna. VIII. A fragmentary skull of a large thecodont,
Luperosuchus fractus. Breviora , 373, 1-8.

sereno, p. c. 1984. The phylogeny of the Ornithischia, a reappraisal. In reif, w.-e. and westphal, f. (eds.).
Third Symposium on Mesozoic Terrestrial Ecosystems , Tubingen 1984 , Short Papers, 219-226. Attempto
Tubingen.

sill, w. D. 1974. The anatomy of Saurosuchus galilei and the relationships of the rauisuchid thecodonts. Bull.
Mus. comp. Zool. 146, 317-362.

strobel, w. and wurm, f. 1977. Erlauterungen zu Blatt 7220 Stuttgart-Siidwest. Geol. Karte Baden- Wiirttemb.
1:25 000, 7220, 1 191.

tucker, M. e. and benton, M. J. 1982. Triassic environments, climates and reptile evolution. Palaeogeogr.,
Palaeoclimatol., Palaeoecol. 40, 361-379.

van heerden, J. 1979. The morphology and taxonomy of Euskelosaurus (Reptilia: Saurischia; late Triassic)
from South Africa. Navors. Nas Mus. Bloemfontein, 4, 21-84.
walker, a. d. 1964. Triassic reptiles from the Elgin area: Ornithosuchus and the origin of carnosaurs. Phil.
Trans. R. Soc. Loud. 248, 53 1 34.

wild, r. 1973. Die Triasfauna der Tessiner Kalkalpen. XXIII Tanystropheus longobardicus (Bassam) (Neue
Ergebnisse). Schweiz. Palaontol. Abh. 95, 1-162.

1980. The fossil deposits of Kupferzell, Southwest Germany. Mesozoic vertebr. Life, 1, 15-18.

MICHAEL J. BENTON
Department of Geology,
The Queen’s University of
Belfast BT7 INN,

Typescript received 31 January 1985 Northern Ireland

NOTE ADDED IN PROOF

The Er-Ma-Ying Series of China (see Table 1) may in fact be Middle Triassic (Anisian) in age
(Zhen et at. 1985). Welles (1984) describes Teratosaurus suevicus as 'a very large theropod, probably
ancestral to megalosaurs, and is here included in the Megalosauridae’, a view that is not accepted
here.

welles, s. p. 1984. Dilophosaurus wetherilli (Dinosauria, Theropoda), osteology and comparisons. Palaeonto-
graphica (A), 185, 85- 180.

zhen s., zhen b., mateer, n. j. and lucas, s. G. 1985. The Mesozoic reptiles of China. Bull, geol Inst.
Uppsalla, N. S., 11, 133-150.

NEW LATE PALAEOZOIC HYOLITHA (MOLLUSCA)
FROM OKLAHOMA AND TEXAS, AND THEIR
PALAEOENVIRONMENTAL SIGNIFICANCE

by JOHN M. MALINKEY, ROYAL H. MAPES and THOMAS W. BROADHEAD

Abstract. Recovery of over 900 hyoliths from fourteen localities in Oklahoma and Texas greatly increases
the number of late Palaeozoic hyolith occurrences in North America; they include Lirotheca wilsoni Malinky
and Mapes, 1983 and Darwinites grafordensis gen. et sp. nov. Many of the hyoliths lack opercula and
taxonomically important features of the aperture, or they are crushed; these specimens are indeterminate. In
Oklahoma the hyoliths are restricted to the dark grey to black, non-fissile, phosphatic shale members ( =
'core’ shales) of Pennsylvanian cyclothems. These shales are thought to be the most offshore facies of the
cyclothem. The occurrence of hyoliths in dark grey, locally phosphatic, shale members of cyclothems farther
south in Texas further supports the assignment of these shales to offshore, slightly oxygen-poor marine
environments rather than to shoreline lagoons.

Late Palaeozoic hyoliths are little known because of their rare occurrence and generally poor
preservation. Hyoliths range from early Cambrian to late Permian, but are only abundant in the
Lower Palaeozoic. Bulk sampling of shales in Oklahoma and Texas to recover bactritoid cephalo-
pods (Mapes 1979) has demonstrated that hyolith abundance and diversity are greater in the late
Palaeozoic than was previously believed.

The first record of a Pennsylvanian hyolith is Hyolithes carbonaria Walcott, 1884, probably from
the Ely Limestone in eastern Nevada. Walcott termed the unit from which he recovered his specimen
the ‘Lower Carboniferous limestone’, although subsequent investigations have demonstrated that
unit to be early Pennsylvanian rather than late Mississippian in age (Larson and Langenheim 1979).
No other Pennsylvanian specimens were known (Yochelson and Saunders 1967) until Lirotheca
wilsoni Malinky and Mapes, 1983 was discovered in the Eudora Shale Member of the Stanton
Formation in south-eastern Kansas and in the Wolf Mountain Shale Member of the Graford
Formation in north-central Texas. The facies in which that species was discovered represents an
offshore, oxygen-poor, though otherwise normal marine environment at the Kansas locality (Heckel
1975) and probably at the Texas locality as well (Malinky and Boardman 1983, 1984). L. wilsoni
was the first hyolith to be recovered from an oxygen-stressed environment in the late Palaeozoic,
and the first North American hyolith to be assigned to a genus other than Hyolithes Eichwald,
1840. Now over 900 additional specimens have been recovered from localities in Oklahoma and
Texas. These specimens enhance our knowledge of the palaeoecology and palaeoenvironmental
preferences of late Palaeozoic hyoliths, and help to clarify the concept of Hyolithes Eichwald,
1840. Our purpose is to document these occurrences and briefly discuss their palaeoenvironmental
significance.

PALAEOENVIRONMENTAL SIGNIFICANCE

Pennsylvanian strata in the northern Midcontinent are dominated by transgressive-regressive lithic
sequences, or cyclothems. The furthest offshore unit of each cyclothem usually consists of a fissile
black phosphatic shale facies at the base and a non-fissile grey shale facies at the top (text-fig. 1).
These facies constitute the ‘core’ shale (Heckel and Baesemann 1975), so called because it usually

I Palaeontology, Vol. 29, Part 2, 1986. pp. 303-31 2. |

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PALAEONTOLOGY, VOLUME 29

occupies a central position between an underlying transgressive limestone and an overlying regres-
sive limestone. The black facies is thought to represent an anoxic, offshore, marine environment,
deposited below a layer of anoxic water at maximum transgression; the grey shale is interpreted as
a dysaerobic offshore facies, emplaced with the partial return of bottom oxygen at the start of
regression (Heckel 1977). The lithic character and stratigraphic position of northern Midcontinent
‘core’ shales provides for their easy recognition; in the southern Midcontinent, however, and
particularly in Oklahoma, the distinctive lithic character of the ‘core’ shales is lost at some localities
because the black fissile facies is absent. Additionally, these southern Midcontinent cyclothems
are usually dominated by shale which further obscures their cyclicity. The identification of ‘core’
shales in the southern Midcontinent is therefore made more difficult because of lithic similarities
between ‘core’ shales and the nearshore shales, and because of the absence of limestones.
Such shale-dominated cyclothems in this region define the terrigenous-detrital facies belt (Heckel
1968).

text-fig. 1. Diagram showing distribution of Hyolitha and other commonly occurring macroinvertebrates
within Midcontinent Pennsylvanian cyclothems. Relative thickness of vertical lines indicates relative abun-
dance of taxa; thick lines indicate common taxa; thin lines indicate scarce taxa. 'Tubes’ refer to problematic
organisms of uncertain affinities now under study. Lithologic symbols standard. Cyclothem modified after

Heckel (1977).

The palaeontological character of northern Midcontinent ‘core’ shales is distinctive; the abun-
dance and diversity of conodonts attains a maximum in the black ‘core’ shale, and several conodont
taxa are restricted to that facies (Heckel and Baesemann 1975). In contrast, the distribution of
conodonts in some ‘core’ shales from the terrigenous-detrital facies belt may be irregular and does
not follow the patterns seen elsewhere. The ‘core’ shale interval in these cyclothems was recognized
by Boardman et at. (1984), using the distribution of macrofaunal assemblages throughout the
cyclothem. They amplified and applied the community succession model of Calver (1968), which
was derived from faunal distribution in Westphalian cyclothems of Great Britain, to cyclothems in

MALINKY, MAPES AND BROADHEAD: LATE PALAEOZOIC HYOLITHA

305

the terrigenous-detrital facies belt. They determined that the Caneyella, Dunbarella- ammonoid-
radiolarian community, which usually occurs in a black, phosphatic shale, occupied the most offshore
position, whereas the Trepospira , Sinuitina-ammonoid-Anthraconeilo community, in medium to dark
grey shales, occurs in facies marking the start of regression. This latter community has been divided
into two, including the Sinuitina- juvenile ammonoid - Anthrciconeilo subcommunity which includes
rare corals, trilobites, echinoderms (including blastoids), and sponges; molluscs are common and
include gastropods, bivalves, cephalopods, scaphopods, rostroconchs, and polyplacophorans;
faunal diversity is high, but the abundance of organisms varies among localities.

The majority of hyoliths collected to date from localities in the terrigenous-detrital facies belt were
discovered within dark grey ‘core’ shales containing the Sinuitina- juvenile ammonoid -Anthrciconeilo
subcommunity (text-fig. 1), although the relative abundance of hyoliths in that community is highly
variable among localities. Hyolith occurrences in the Smithwick Formation (Atokan) and the
Deese Group (Desmoinesian) have not been investigated in the same detail as those from other
Midcontinent localities. These two units apparently represent a wide range of environments (Fay el
al. 1979; Kier et al. 1979), although cephalopods, trilobites, blastoids, and other fauna at the
same position as the hyoliths suggest that the hyolith-bearing units represent offshore marine
environments.

The apparent restriction of Midcontinent Pennsylvanian hyoliths to known ‘core' shales in the
terrigenous-detrital facies belt in Oklahoma probably reflects a genuine preference for that environ-
ment. Numerous early and more recent palaeontological studies of the limestones and other near-
shore units in cyclothems (e.g. Mudge and Yochelson 1962; Moore 1964), and recent petrologic
and petrographic studies of the limestones (see Heckel 1984, bibliography) have failed to locate
hyoliths. Thus, the occurrence of hyoliths only in ‘core’ shale members of Midcontinent Penn-
sylvanian cyclothems provides an additional tool for the recognition of such ‘core’ shales in areas
where other evidence is inconclusive or ambiguous.

The cyclic nature of Pennsylvanian strata in north-central Texas has long been recognized,
although the furthest offshore unit has been in dispute. Diversely fossiliferous shales above the
basal fluvial/deltaic package in these cyclothems have formerly been interpreted as lagoonal in
origin (Erxleben 1975), with the overlying limestone regarded as the most offshore facies. Malinky
and Boardman (1983, 1984) suggested that the fossiliferous shale is a ‘core’ shale, depositionally
similar to those from northern Midcontinent localities. This interpretation is base upon high faunal
diversity, the presence of phosphate nodules at many localities, and diagenetic patterns in the
limestone members of these cyclothems. Hyoliths have been recovered only from the diversely
fossiliferous shale members of Texas cyclothems, such as the Wolf Mountain Shale (Graford
Formation; Missourian), the Finis Shale, Bluff Creek Shale, and Wayland Shale (all Graham
Formation; Virgilian). Their occurrence in the shale facies suggests that such units are ‘core’ shales
and supports the assignment of these shales to offshore marine environments rather than to marginal
marine lagoons.

SYSTEMATIC PALAEONTOLOGY

Introductory comments. Outside Eastern Europe and the Soviet Union the taxonomy of the Hyolitha has long
been neglected, and remains particularly underdeveloped in North America. The generic name Hyolithes
Eichwald, 1840 has been extensively used for many North American hyolith species; at one time it encompassed
over 360 species (Sinclair 1946). This broad generic concept is the result of a vague and generalized original
description of Hyolithes by Eichwald (1840, p. 97) in which only the sub-triangular transverse outline of the
shell and the presence of apical septae were noted. Much of the original description consisted of discussion of
possible affinities, a matter still of argument. Consequently, a variety of organisms possessing shells with
generally sub-triangular transverse sections came to be included in Hyolithes. All species now encompassed
by that genus warrant re-examination.

Syssoiev (1958, 1959) emended Hyolithes but still retained a variety of transverse shapes within the
genus. We prefer a generic concept more closely conforming to Eichwald’s original specimens as illustrated
by Fisher (1962, p.W123, fig. 61.\a-d). We consider Hyolithes to have a broad, depressed dorsum.

306

PALAEONTOLOGY, VOLUME 29

grading into a pronounced longitudinal sulcus at each edge of the dorsum, and rounded lateral margins. The
venter is slightly inflated and the ligula is low and ventrally curved. The dorsal apertural margin has a flare
and the transverse section is sub-triangular. The apical end of the shell curves dorsally. The operculum is
unknown.

The standards of quality for type specimens of Hyolithes species have changed. Now only specimens
retaining well-preserved apertural detail should be used as types. The apertural features, as well as a number
of other characters of the conch and operculum, have been used for generic and specific level taxonomy
(Marek 1 966c/) although we judge that a well-preserved conch lacking an operculum, or even the internal
mould of the conch, can be confidently identified to genus and species in some taxa.

Repository. All specimens are housed in the National Museum of Natural History, Washington, DC.

Phylum MOLLUSC A
Class hyolitha Marek, 1963
Order hyolithida Matthew, 1899
Family hyolithidae Nicholson fide Fisher, 1962
Genus darwinites gen. nov.

Type species. Darwinites grafordensis gen. et sp. nov.

Diagnosis. Hyolith having a small ligula on the ventral apertural margin, a low dorsal ridge
with flattened flanks, and a depressed sub-triangular transverse section; the aperture is expanded
noticeably, and the mould tapers rapidly to a pointed apex.

Discussion. The absence of longitudinal sulci and an apertural flare on the dorsum of Darwinites
clearly distinguish it from Hyolithes. Furthermore, Darwinites possesses a dorsum with a narrowly
rounded median keel, whereas the dorsum on Hyolithes is rounded. The low ventral shelf, narrowly
rounded dorsal ridge, and conical shape of Darwinites separate it from Lirotheca Malinky and
Mapes, 1983 (from the Pennsylvanian of Kansas). Furthermore, the dorsal ridge on Lirotheca is
inflated rather than depressed and the ventral ligula is larger. These features support generic status
for Darwinites.

Etymology. This genus is named for Darwin R. Boardman in recognition of his work in field and laboratory
studies of Midcontinent stratigraphy and palaeontology.

Darwinites grafordensis gen. et sp. nov.

Text-fig. 2a-c

Diagnosis. See genus.

Material. Three specimens: holotype, USNM 390488, loc. V-2, Virgilian; paratype, USNM 390487, loc.
M-3, Missourian; and paratype, USNM 390489, loc. V-3, Virgilian. See Appendix for locality details.

Description. The dorsum possesses a low median dorsal ridge, with a narrowly rounded crest and flattened
flanks adjacent to it. The lateral margins are broadly rounded and the venter is flat with a small ligula along
the apertural margin. The transverse shape is depressed, and the mould tapers rapidly toward the apex. The
apex curves slightly toward the dorsum.

Closely spaced transverse lirae occur on the internal mould of the dorsum (text-fig. 2a), and a faint sulcus
is present along each edge of the venter near the apertural end. The operculum has a single set of clavicules
(monoclaviculate). The conical shield is large and flattened, whereas the cardinal shield is smaller and indistinct.
Other details of the mould and the shell are unknown.

The three specimens occur as limonitized internal moulds and only the holotype is well preserved. The
holotype is 2-5 mm long, with an apertural width (W) of 2-5 mm and apertural height (H) of 17 mm. The
paratypes are comparable in size.

Discussion. Darwinites is monospecific. D. grafordensis is the second hyolith species to be discovered
in the Midcontinent Pennsylvanian of North America, and only the second North American hyolith

MALINKY, MAPES AND BROADHEAD: LATE PALAEOZOIC HYOLITHA

307

text-fig. 2. SEM photomicrographs of Midcontinent Pennsylvanian Hyolitha. All specimens are internal
moulds. A-c, Darwinites grafordensis gen. et sp. nov. a, lirae on left flank of dorsum, holotype, USNM
390488, Virgilian, loc. V-2, x 240; b, dorsum, holotype, x 20; c, dorsum, paratype, USNM 390487,
Missourian, loc. M-3, x 20. d, Lirotheca wilsoni Malinky and Mapes, 1983: dorsum showing prominent
moulds of clavicles on operculum, hypotype, USNM 390490, Virgilian, loc. V-2 x 10. e-h, Hyolitha
incertae sedis. e, lirae on left flank of dorsum, USNM 390468, Desmoinesian, loc. D-l, x 240; f, dorsal
view showing fragmentary monoclaviculate operculum, USNM 390466, Desmoinesian, loc. D-l, x 8-2; g,
dorsal view showing fragmentary operculum, USNM 390495, Virgilian, loc. V-3, x 5-4; h, venter, USNM

390485, x 5-0.

taxon assigned to a genus other than Hyolithes. Similarly preserved species belonging to closely
related genera include L. wilsoni Malinky and Mapes, 1983. Differences between those genera have
been noted above.

Etymology. The species is named for the Graford Shale, in which hyoliths were first discovered in Texas.

Genus lirotheca Malinky and Mapes, 1983
Types species. Lirotheca wilsoni Malinky and Mapes, 1983, p. 348.

Diagnosis. Hyoliths having a narrowly rounded dorsum with a prominent flare along the dorsal
apertural rim and a ventral ligula; the dorsum has a narrowly rounded median keel; the transverse
section is inflated and sub-triangular.

308

PALAEONTOLOGY, VOLUME 29

Discussion. Differences between this genus and Hyolithes Eichwald, 1840 were noted by Malinky
and Mapes (1983), while differences between it and Darwinites were discussed above. The occurrence
of Lirotheca at new localities in Oklahoma and Texas extends its geographic range from south-
eastern Kansas, and its discovery in Virgilian strata extends its stratigraphic range from Missourian
only into the Desmoinesian and Virgilian.

Lirotheca wilsoni Malinky and Mapes, 1983
Text-fig. 2d

1983 Lirotheca wilsoni Malinky and Mapes, p. 348, fig. 1a-c, f, g.

Diagnosis. See genus.

Material. Four specimens: hypotypes, USNM 390490 and 390491, loc. V-2, Virgilian; USNM 390492, loc. D-
1, Desmoinesian; and USNM 390493, loc. V-3, Virgilian. See Appendix for locality details.

Description. The dorsum is inflated and possesses a narrowly rounded median keel with inflated flanks adjacent
to it. The lateral margins are rounded, and shallow indentations occur on the apertural rim along the lateral
margins. A shallow sinus also occurs along the aperture where the dorsal keel and apertural rim intersect, and
the entire apertural rim is flared. The venter is flat, and the ventral ligula is strongly curved toward the venter.
The apex curves slightly toward the dorsum.

Faint transverse lirae cover much of the dorsum. The lirae are straight across the flanks of the dorsal ridge
but curve on the ridge crest to create a shallow sinus. Transverse lirae also cover much of the venter. A sulcus
is present along each margin of the venter; each extends from the shelf about three-quarters the length of the
mould toward the apex.

The operculum is monoclaviculate with well-developed clavicles near the dorsal edge. The conical shield on
the ventral side is flat whereas the dorsal cardinal shield and furrows are inconspicuous. No lirae occur on the
operculum.

Discussion. The recovery of these larger, well-preserved specimens of L. wilsoni affords the oppor-
tunity to supplement the description of the holotype and paratypes, especially concerning details
of the operculum. On the holotype the clavicles are covered with sediment, whereas on these speci-
mens the clavicles are well exposed, so that their monoclaviculate nature is certain. The holotype
from the Eudora Shale in Kansas is smaller than the specimens described above, and may repre-
sent a juvenile.

Class hyolitha incertae sedis
Text-fig. 2e-h; Table 1

Material. More than 900 specimens, with a distribution among localities shown in Table 1. See Appendix for
locality details.

Description. The dorsum on specimens included under this heading varies from depressed to inflated, and the
keel on the dorsum varies from angular to narrowly rounded. The lateral margins on most are also narrowly
rounded, and the venter ranges from flat to slightly inflated. The transverse section varies from inflated to
depressed sub-triangular. All specimens are elongate, reflecting a low angle of apical expansion.

The apex varies from straight on most specimens to curved, either dorsally or ventrally, or to the left or
right when viewed from the dorsum. A few specimens have fragmentary monoclaviculate opercula; otherwise
no apertural detail is known.

Most specimens are preserved as limonitized internal moulds. The moulds are generally smooth, although
on a few specimens they show faint, closely spaced, transverse lirae near the apertural end. Some specimens,
particularly those from the Deese Group, retain shells, but they are crushed, partially dissolved, and preserve
little detail. All other features of these specimens are unknown.

Discussion. Specimens included under this heading are regarded as incertae sedis below the class
level because they lack the apertural features necessary to confidently assign them at lower taxo-
nomic levels. Three orders are currently included in the class Hyolitha: the Hyolithida, Orthothecida,

MALINKY, MAPES AND BROADHEAD: LATE PALAEOZOIC HYOLITHA 309

and Toxeumorphida (Peel and Yochelson 1984). The Hyolithida are distinctive because of the ligula
along the ventral apertural rim; their opercula are subdivided into cardinal and conical shields
separated by furrows, and the interior of the opercula possesses one or more pairs of processes
termed clavicles (Marek 1966a, p. 71, fig. 10a-c); transverse sections are sub-triangular. The
Orthothecida lack the ventral ligula, and their opercula have neither shields nor interior clavicles
(Marek 19666, p. 91, figs, a, b); transverse sections on some are kidney-shaped whereas on others
they are sub-triangular like those of hyolithids (Marek 1966a, p. 59, fig. 3). The Toxeumorphida
are poorly known, although available specimens suggest strongly that their transverse shapes are
circular. All the current specimens have sub-triangular transverse sections, so that the Toxeumor-
phida are probably not represented.

table 1. Distribution of hyoliths listed under Hyolitha incertae sedis in
southern Midcontinent ‘core’ shales. Details of localities are given in the
Appendix. Sample weights are approximate. All specimens have been de-
posited at the National Museum of Natural History (USNM).

Locality

Sample weight ( kgm )

Number of specimens

Number

A- 1

2000

19

390463

A-2

270

7

390464

D 1

136

571

390465-390469,
390481, 390483,
390484, 390494

D-2

22-7

1

390470

D 3

109

5

390471

D-4

680

3

390472

D 5

109

33

390473

M- 1

0-5

1

390474

M-2

0-5

2

390475

M3

680

47

390476, 390495,
390496

V-l

45

1

390477

V-2

432

195

390478, 390482

V-3

432

134

390479, 390485,
390486

V-4

108

4

390480

Except for the few specimens retaining fragmentary opercula (text-fig. 2f, g), no Pennsylvanian
specimens can be confidently placed in either the Hyolithida or Orthothecida. The specimens with
opercula are undoubtedly hyolithids because the remains of clavicles are clearly evident on the
opercula, despite poor preservation otherwise. Among the other specimens the lack of well-preserved
apertural characteristics preclude distinction between the Hyolithida and Orthothecida. By them-
selves, transverse outline, lirae, or other features of the moulds cannot be used to diagnose or
recognize hyolith taxa at any level (Marek 1966a). Better preserved specimens from Oklahoma and
Texas may demonstrate that several taxa are present in the Midcontinent Pennsylvanian .

Acknowledgements. Partial support for this study was provided by the Smithsonian Institution in the form of
a Postdoctoral Fellowship to J. M. M. Thanks are due to the Ohio University Research Committee and to

310

PALAEONTOLOGY, VOLUME 29

the donors of the Petroleum Research Fund, administered by the American Chemical Society, for partial
support to R. H. M. (PRF No. 15821-AC2). We thank E. L. Yochelson (U.S. Geological Survey) and R. E.
Grant (National Museum of Natural History) for their comments on the manuscript. Heidi Wolff assisted
with the SEM.

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calver, m. a. 1968. Distribution of Westphalian marine faunas in northern England and adjacent areas.
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— 1975. Stratigraphy and depositional framework of the Stanton Formation in southeastern Kansas. Bull.
Kans. Univ. geol. Surv. 210, 45 pp.

— 1977. Origin of black phosphatic shale facies in Pennsylvanian cyclothems of Mid-Continent North
America. Bull. Am. Ass. Petrol. Geol. 61, 1045-1068.

1984. Factors in Mid-Continent Pennsylvanian limestone deposition. Tulsa geol. Soc. Spec. Pubis, 2,
25-50.

— and baesemann, j. f. 1975. Environmental interpretation of conodont distribution in Upper Penn-
sylvanian (Missourian) megacyclothems in southeastern Kansas. Bull. Am. Ass. Petrol. Geol. 59, 486-
509.

kier, r. s. et al. 1979. The Mississippian and Pennsylvanian (Carboniferous) Systems in the United States—
Texas. Prof. Pap. U.S. geol. Surv. 1 1 10-S, S1-S45.

larson, E. R. and langenheim, R. L. 1979. The Mississippian and Pennsylvanian (Carboniferous) Systems in
the United States— Nevada. Ibid. 1 1 10-BB, BB1 -BB19.
malinky, j. m. and boardman, d. r. 1983. Recognition of offshore ‘core’ shale deposition in cyclothems of
Texas and northern Midcontinent. Abstr. Progm geol. Soc. Am. 15, 5.

1984. Depositional significance of faunal and diagenetic trends in Pennsylvanian cyclothems,
North-Central Texas. Ibid. 16, 583.

and mapes, R. H. 1983. First occurrences of Hyolitha (Mollusca) in the Pennsylvanian of North America.
J. Paleont. 57, 347-352.

mapes, r. h. 1979. Carboniferous and Permian Bactritoidea (Cephalopoda). Paleont. Contr. Univ. Kans. 64,
75 pp.

and furnish, w. m. 1981. The Pennsylvanian ammonoid family Welleritidae. J. Paleont. 55, 317-330.

marek, l. 1966u. The Class Hyolitha in the Caradoc of Bohemia. Sb. geol. Ved. Praha ( Paleontol .), 9,
51-113.

19666. New hyolithid genera from the Ordovician of Bohemia. Cas. narod. Mus. 135, 89-92.
moore, R. c. 1964. Paleoecological aspects of Kansas Pennsylvanian and Permian cyclothems. Bull. Kans.
Univ. geol. Surv. 164, 287-380.

mudge, M. M. and yochelson, E. L. 1962. Stratigraphy and paleontology of uppermost Pennsylvanian and
lowermost Permian rocks in Kansas. Prof. Pap. U.S. geol. Surv. 323, 213 pp.
peel, J. s. and yochelson, E. l. 1984. Permian Toxeumorphida from Greenland: an appraisal of the molluscan
class Xenoconchia. Lethaia , 17, 21 1-221.

Sinclair, g. w. 1946. Notes on the nomenclature of Hyolithes. J. Paleont. 20, 72-85.
syssoiev, v. a. 1958. The superorder Hyolithoidea. Osn. Paleont. Akad. Nauk SSSR , 2, 184-190.

1959. The systematics of the hyolithids. Dokl. Akad. Nauk SSSR, 125, 397-400.

MALINKY, MAPES AND BROADHEAD: LATE PALAEOZOIC HYOLITHA 311

tucker, j. k. and mapes, r. h. 1978. Coiled nautiloid cephalopods from the Wolf Mountain Shale (Penn-
sylvanian) in North-Central Texas. J. Paleont. 52, 596-604.
walcott, c. d. 1884. Paleontology of the Eureka District, Nevada. Monogr. U.S. geol. Surv. 8, 298 pp.
yochelson, E. L. and saunders, w. b. 1967. A bibliographic index of Late Paleozoic Hyolitha, Amphineura,
Scaphopoda and Gastropoda. Bull. U.S. geol. Surv. 1210, 271 pp.

JOHN M. MALINKY
Department of Paleobiology
National Museum of Natural History
Washington, DC 20560, USA

ROYAL H. MAPES

Department of Geology
Ohio University
Athens, Ohio 45701, USA

THOMAS W. BROADHEAD
Department of Geological Sciences

Typescript received 6 March 1985 University of Tennessee

Revised typescript received 13 September 1985 Knoxville, Tennessee 37996, USA

APPENDIX

List of localities

ATOKAN

A-l: Smithwick Formation. Shale exposed 5-6 km east and 1-4 km south of US Highway 190 and county
road FM 1121 junction, near Rochelle, McCulloch Co., Texas (Speck Mountain 7-5' quad.; Mapes and
Furnish 1981).

A-2: Atoka Formation. Shale exposed on the north bank of Delaware Creek approximately 100 m east
of state highway 48, approximately 2 4 km north of Wapanucka, Johnston C., Oklahoma (NW1/4 SW1/4
SW1/4, sec. 1, T2S, R8E, Wapanucka 7-5' quad ).

DESMOINESIAN

D-l:Deese Group. Limited shale exposure in cutbank of unnamed stream on the Daube Ranch, near
Mannsville, Johnston Co., Oklahoma (SW1/4 SW1/4 SE1/4, sec. 31, T3S, R4E, Mannsville 7-5' quad; loc. P-
10 of Mapes 1979).

D-2: Atwood Shale (Lower Wewoka 2). Shale exposed on north side of state highway 12, 3-8 km south-
west of the junction of state highways 12 and 48 in Allen, Pontotoc Co., Oklahoma (SW1/4 SE1/4, sec. 13,
T5N, R8E, Lake Holdenville 7-5' quad.).

D-3: Wewoka Shale. Shale exposed in the east bank of unnamed stream at the shoreline of Lake Okmulgee
in Okmulgee State Recreation Area, 9-6 km west of Okmulgee, Okmulgee Co., Oklahoma (NE1/4 SE1/4
SW1/4, sec. 18, T13N, R12E, Lake Okmulgee 7-5' quad ).

D-4: Wewoka Shale. Shale exposed 3-2 km east and 3-2 km south of Homer, Pontotoc Co., Oklahoma.
Shale crops out 120 m east of north-south road in a gully (Sl/2 NW1/4 SW1/4, sec. 4, T3N, R7E, Francis
7-5' quad.; loc. P-8 of Mapes 1979).

D-5: lake Neosho Shale Member of Altamont Formation. Shale not in place; exposed in a now overgrown
vacant lot adjacent to and parallel with US Highway 51, 0-2 km south of 129th St. exit. Broken Arrow, Tulsa
Co., Oklahoma (NE1/4 NE1/4, sec. 32, T19N, R14E, Broken Arrow 7-5' quad.).

MISSOURIAN

M-l: unnamed shale (probably equivalent to Exline). Shale exposed in stream bank south-west of Mound
Valley, Labette Co., Kansas (centre line west, SE1/4 NW1/4, sec. 25, T6N, R7E, Mound Valley 7-5' quad.).

M-2: Tackett Shale (probably equivalent to Exline). Shale exposed in a series of gullies 2-4 km north of
Sasakwa, Seminole Co., Oklahoma (centre line west, SE1/4 NW1/4, sec. 25, T6N, R7E, Sasakwa 7-5' quad.).

312

PALAEONTOLOGY, VOLUME 29

M-3: Wolf Mountain Shale Member of Graford Formation. Shale exposed in a construction site for a
housing project on west side of Lake Bridgeport; exposure is 0 8 km west and 0-8 km south of the junction of
US Highway 380 and the Lake Bridgeport bridge. Wise Co., Texas (Wizard Wells 7-5' quad.; loc. 3 of Tucker
and Mapes 1978; and see Malinky and Mapes 1983).

VIRGILIAN

V- 1 : Finis Shale Member of Graham Formation. Shale exposed 0-8 km north-east of oil storage tanks on
Curtis Ranch, 1-9 km east of US Highway 281, 3-5 km south-east of Jacksboro, Jack Co., Texas (Jacksboro
Northeast 7-5' quad.).

V-2: Bluff Creek Shale Member of Graham Formation. Shale exposed 1-6 km south-east of end of a private
road near a pond dam; the road is located 9-6 km north-east of Whon, along the road connecting Whon and
Trickham, Coleman Co., Texas (Speck Mountain 7-5' quad.).

V-3: Bluff Creek Shale. Exposure located near a pond dam 0-69 km east of county road FM 568 and 17-5
km south of Bangs, Brown Co., Texas (Bangs 7-5' quad.).

V-4: Wayland Shale Member of Graham Formation. Shale exposed on south-west side of hill 0-2 km north
of road connecting Whon and Trickham, and 2-6 km east of intersection of that road and the private road
leading to locality V-l, Coleman Co., Texas (Speck Mountain 7-5' quad.).

TAXONOMY, PHYLOGENY, AND VARIABILITY OF
PSEUD/ SOGRAPT US BEAVIS

by r. a. cooper and ni yunan

Abstract. Manubriate isograptids from the Castlemainian and Yapeenian (Arenig) of New Zealand, Austral-
ian, and Chinese collections are described and analysed in terms of population systematics. Pseudisograplus
manubriatus (T. S. Hall, 1914) is divided into five subspecies, of which P. m. koi , P. m. harrisi , P. m. Janus, and
P. m. texanus are new; P. bellulus sp. nov. and five other Pseudisograplus species are described. A tentative
phylogenetic scheme is constructed from their stratigraphic occurrence and a cladogram of pseudisograptids
and other forms with manubriate features. Similarities in proximal structure and thecal form link the pseudiso-
graptids with the glossograptids, and the monophyletic suborder Glossograptina Jaanusson, here taken to
include Apiograptus (syn. Exigraptus ), Kalpinograptus (syn. Apoglossograptus), and Pseudisograplus, is down
graded to family rank. The paraphyletic Pseudisograplus is a sister group to the monophyletic subfamily
Glossograptinae.

Details of proximal development and structure of the manubrium are described for P. m. Janus and P.
bellulus, using pyritized specimens preserved in full relief. From this data and that gleaned from flattened
specimens of other taxa it is concluded that the manubrium structure described by Bulman, and taken to be a
paradigm for the group, is in fact rare and atypical

Pseudisograptus manubriatus is an extraordinary species, even among isograptids, for its wide
range of morphologic variation. Previous workers have referred to or described this variation (Hall
1914; Harris 1933; Cooper 1973, 1979; Cooper and McLaurin 1974) and four informal forms were
erected by Cooper and McLaurin (Forms A-D) who remarked (p. 78): ‘although [the forms] are
linked by intermediates and are unlikely to prove to be distinct taxa, they do appear to represent
end points along different lines of variation’. In this study we approach the problem from the point
of view of population systematics and revise the entire group of manubriate isograptids, here
referred to as the manubriate complex. The group is united by possession of a manubrium. The
study is based on the original collections from New Zealand of Cooper (1973; with locality details),
supplemented in all cases by additional material; collections from Willey’s Quarry, Macedon,
Victoria, made by several workers; and new material from Zhejiang Province in China, including
pyritized specimens in full relief which allows proximal development and structure of the manubrium
to be described in detail and analysed.

The stratigraphic ranges of the taxa discussed are shown in text-fig. 4. The ranges of British
species within the Isograptus caduceus gibberulus Zone (as redefined by Jenkins 1982) is un-
known (Jenkins 1982, p. 240), and their range is shown throughout the interval correlated with
that zone (upper Castlemainian to lower Yapeenian). The earliest form, P. hastatus, appears in
the lower part (I. victoriae maximus) of the Castlemainian Ca3 zone of Australasia. The main
radiation took place in the early Yapeenian and by the end of the Yapeenian all pseudisograptids
had disappeared.

Geographically the group is rather less widespread than isograptids of the victoriae and caduceus
groups. Apart from the Australian, Texan, and Chinese species discussed herein, the group is
represented in Alaska (P. gracilis; Carter and Tailleur 1984, fig. 6) and the Basin Ranges, USA (P.
dumosus; listed by Ross and Berry 1963, p. 94), and Kazakhstan (Tsai 1974 lists forms here
attributed to P. manubriatus koi and P. dumosus). Kalpinograptus is known from NW China
(Xinjiang; Jiao 1977) and Alabama (Finney 1978 as Apoglossograptus), and Apiograptus is known
from Sweden (Cooper and Lindholm 1984). The glossograptids are world-wide.

[Palaeontology, Vol. 29, Part 2, 1986, pp. 313-363, pis. 24-27.|

314

PALAEONTOLOGY, VOLUME 29

MANUBRIATE MORPHOLOGY, VARIATION, AND ANALYSIS

A feature of all isograptid populations described to date is the wide range of intraspecific morpho-
logic variation (Cooper 1973; Cooper and Fortey 1982). Failure to appreciate this wide range can
lead to invalid splitting of taxa (Beavis and Beavis 1974). The range of morphologic variation
displayed by the manubriate species, however, and particularly P. manubriatus , is exceptionally
great. It is more important than ever to adequately describe the variation and adopt a population
approach to the systematics of the group. We have used statistical analysis of measurable characters
to describe this variation quantitatively and discuss below the measured characters and techniques
used. The most useful features for taxonomic purposes relate to the proximal portion of the
rhabdosome (Cooper and Fortey 1982, 1983) and we have therefore concentrated on this region.

The manubrium

The term manubrium has come into general use for the structure produced by the initial downward
growth of proximal thecae prior to the upward flexure of stipes in isograptids. Because it is regarded
as apomorphous (a defining character) for the manubriate complex and because its size and shape
have been found to be useful in discriminating taxa it is here defined with more precision than in
the past. It is comprised of the proximal portions of initially downward growing thecae (th 1 2 and
beyond). Its base is taken at the level of the sharp upward flexure in the dorsal stipe margin (text-
fig. 2a) at the point of origin of the third or later thecal pair. Beyond this point the two thecal series
grow independently outward and upward as the stipes proper. The structure of the manubrium is
known from three species preserved in relief: P. bellulus sp. nov., P. manubriatus texanus ssp. nov.,
and P. m.janus ssp. nov.

text-fig. 1. Manubrium development in Pseudisograptus manubriatus koi
(strongly developed) and P.l geniculatus (weakly developed). Corymbograptus
retroflexus is shown for comparison, with initially downward growing stipes which
do not form a manubrium.

The manubrium results from a lengthening of the sicula and proximal thecae and delay in point
of upward flexure of the dorsal stipe margins, together with a concentration of thecal origins. It is
distinguished from analogous (not homologous) structures in other didymograptids in which down-
ward initial growth of stipes is not accompanied by elongation of proximal thecae and the rhabdo-
some has a proximally concave ventral outline (text-fig. 1).

In all manubriate species for which data are available the growth paths of the sicula and first
theca overlap each other in mid-length, as seen in bilateral view, but recurve so that their apertural
regions are directed away from each other. This curved growth path is followed and often accentu-
ated by subsequent thecae. The alternate superposition of one theca on another in the two thecal
series results in a plaited arrangement of proximal thecae— clearly illustrated by Bulman (1968,

COOPER AND NI: PSEUDISOGRAPTUS

315

fig. 1) and reaching its most elaborate state in P. m. janus where the first five thecae are plaited
(text-fig. 18). The extensive overlap of one thecal series on the other, illustrated by Bulman
in the specimen from Texas ( P . m. texas ) and for a time taken as a paradigm for the group (Beavis
1972; Cooper and McLaurin 1974) is now known to be rare; with the exception of Kalpinograptus ,
there is generally no overlap in specimens other than that from Texas.

Development of the manubrium takes place entirely on the reverse side of the rhabdosome and
the two sides (obverse and reverse) can appear very different, as in P. m. janus. Other features of
the manubrium, such as the left- or right-hand origin of thecae and the tendency for the stipe dorsal
margin to grow around in a loop at the point of flexure, are discussed with the species concerned.

Morphologic terms

Rhabdosome characters referred to in the descriptions below are shown in text-fig. 2. Sicula length ,
proximal stipe width , distal stipe width are in general use and need no explanation. The manubrium
is that structure involving the proximal portions of thl2, 21, and all subsequent thecae with initially
downward growth; width and length (= height) of the manubrium are measured as indicated. The
free proximal length of the sicula is measured from the apex to the top of the manubrium. In most
manubriate species the sicula passes apically into a stout nema and the apex of the sicula is
sometimes difficult to determine. From the few well-preserved specimens available the apex of the
sicula passes via a slight constriction into the nema and this constriction is generally visible even in
fully flattened specimens. The possible margin of error in determining the apex of the sicula is only
a small proportion (about 5 %) of total sicula length but is a considerable portion (about 20 %) of
the free proximal sicula length. For this reason, free proximal sicula length was not used for
multivariate analysis.

text-fig. 2. Terms and measured characters used in the descriptions: fsl,
free proximal portion of the sicula; si, sicula length; ml, manubrium length;
mw, manubrium width; ma, manubrium angle; sw, stipe width; sa, stipe

divergence angle.

The manubrium angle is the angle subtended by the manubrium shoulders. Stipe divergence angle
is the ventral (external) angle measured between the chords joining the distal extremity with the
point of proximal flexure (i.e. base of manubrium shoulder) in the dorsal stipe margin. The term
supradorsal is used as defined by Cooper (1973) to refer to that portion of the sicula and proximal
thecae lying above the point of flexure in the dorsal stipe margins. The term infradorsal is introduced
here to refer to that portion below the point of flexure.

The term advanced manubriate thecal form (text-fig. 3) refers to the outline form of thecae, par-
ticularly in the distal part of the rhabdosome, characteristic of Apiograptus and the P. manubriatus -
P. tau group and, of course, of the glossograptid — Kalpinograptus group. Apertural margins
are extended into an outwardly directed ventral process in the manubriate species, homologous
with the apertural spine in glossograptids. The apertural margin is inclined to the stipe axis at a

316

PALAEONTOLOGY, VOLUME 29

high angle and is undulating, suggesting the presence of lateral lappets as described by Skevington
in isolated material of P.l geniculatus. Thecal ontogeny in glossograptids has been discussed by
Finney (1978). The term simple manubriate thecal form refers to thecal outline form in the P.
dumosus-P. gracilis group and in P. hastatus. Distal thecae are relatively straight and apertural
margins are highly inclined but lack a ventral process or suggestion of lateral lappets.

advanced
manubnate form

text-fig. 3. Thecal form: simple manubriate (Pseudi-
sograptus gracilis), and advanced manubriate ( P.
manubriatus koi) Ihecal form contrasted with iso-
graptid thecal form ( Isograptus victoriae victoriae).

Thecal spacing was found to be difficult to measure precisely in rhabdosomes with curved stipes
and to show relatively little variation where it could be measured; it is therefore not used in the
statistical analysis. Thecal inclination similarly can seldom be measured in any precise way in
flattened rhabdosomes and is also not used in analysis.

Isograptid symmetry was defined by Cooper and Fortey (1982) for rhabdosomes with the sicula
and first theca symmetrically disposed on either side of the rhabdosome midline. The term maeandro-
graptid symmetry is used here for rhabdosomes which, in contrast, have the rhabdosome midline
passing through the sicula and th 1 1 and l2 arranged more or less symmetrically on either side, as
exemplified by Maeandrograptus schmalenseei.

The terms obverse and reverse need clarification when being used for pericalycal rhabdosomes
(Bulman 1968, p. 214). As used here reverse refers to that side of the rhabdosome on which th 1 2
grows across the sicula in its early development from th 1 1 . In pericalycal forms such as Cryptograp-
hs (Bulman 1970, fig. 62.3) the distal growth path of th 1 2 may recross the sicula on the obverse
side. On the obverse side of the rhabdosome the sicula is not obscured by the ‘crossing canals’.

The terms pericalycal and platycalycal also need clarification. Pericalycal, as defined by Bulman
(1970, p. V10), refers to ‘mode of development of scandent (monopleural) rhabdosomes associated
with dicalycal th 1 1 and left-handed origin of thl2, sicula becoming largely enclosed on both sides
during subsequent development’. Emphasis was laid by Bulman (1968) on two features: first, thl2
grows sinistrally, its distal portion (in Cryptographs ) wrapping around the obverse side of the
sicula opposite to that of thl1; secondly, development is of artus type (thl1 dicalycal) enabling (or
causing) the two thecal series to develop on opposite sides of the sicula and thereby envelop it. In
contrast platycalycal development refers to the ‘normal’ development mode in which all proximal
budding takes place on the reverse side of the rhabdosome, leaving the sicula free on the obverse
side, e.g. Glyptograptus , Isograptus, etc. The distinction becomes blurred in such monopleural
rhabdosomes as Cryptographs marcidus and Glossograptus ciliatus, both described from isolated
growth stages by Finney (1978), in which development is of ‘normal’ isograptid type (thl2 dicalycal)
but the sicula becomes enveloped by the two thecal series from the second or third thecal pair
onwards. Should precedence be given to a development of sinistral mode and artus type, or to the
envelopment of the sicula? Bulman appears not to have regarded envelopment of the sicula as of
over-riding importance because he comments (1968, p. 214) that P. manubriatus from Texas ‘is
fundamentally platycalycal, though it simulates the pericalycal type to some extent in that the
proximal portions of th4 1 to th6 1 seem to originate on the obverse side of the rhabdosome and
possibly enclose or cover some portion of the sicula. This is probably induced by the semicircular

COOPER AND NI: PSEUDISOG RA PTUS

317

course of th22 and does not constitute a true transition between the two types.’ The proximal
structure of Finney’s species can be regarded as a more extreme expression of this feature (discussed
in detail herein), and therefore would not have been regarded by Bulman as ‘truly’ pericalycal. In
this discussion we use the term pseudopericalycal for forms in which the sicula is enveloped by the
developing thecal series but in which development is of ‘normal’ isograptid type and dextral; it is
known in C. marcidus , G. ciliatus, and probably in Kalpinograptus, and is incipiently developed in
the Texan P. manubriatus. Pericalycal development has been described in C. tricornis (Bulman 1945)
and in G. holmi, Paraglossograptusl sp., and Skiagraptus sp. (= Bergslroemograptus crawfordi
(Harris) of Finney and Chen 1984), all described by Whittington and Rickards (1969). However,
strict definition of the term pericalycal must await resolution of the problem raised by Finney’s
(1978) reinterpretation of the proximal development of C. tricornis and G. holmi.

Measured characters

To quantitatively describe morphologic variation the characters listed below were used. They are
readily measured and assumed to have undergone either no change, or standard change from
specimen to specimen, on flattening.

Sicular length , with a possible 5 % error in determining the apex (mentioned above). Free proximal
sicula length , with a possible 20 % error (mentioned above); this feature must be used with caution
but it is nevertheless a conspicuous and distinctive feature of the rhabdosome in all species. Infra-
dorsal sicula length gives a measure of the proximal ‘depth’ of the rhabdosome. However, it is
merely sicula length from which has been subracted the manubrium length plus the free proximal
sicula length; it is therefore totally dependent on the other two characters and is not used with them
in multivariate analysis. Manubrium height : because of the tendency in rhabdosomes with highly
divergent stipes for the dorsal stipe margin to grow around in a loop and overlap the base of the
manubrium, the point of intersection between the manubrium shoulders and the dorsal stipe margin,
taken as the base of the manubrium, may not in fact be the true base of the manubrium as revealed
in growth stages. The true manubrium length in Pseudisograptus manubriatus koi ‘form D' is
therefore likely to be a little greater than measured in mature rhabdosomes. Manubrium width', as
with manubrium length, true manubrium width in P. m. koi ‘form D’ is likely to be greater than
measured. Manubrium angle : variation in this feature has been noted by most previous workers; it
is very largely a consequence of manubrium length and width and is not therefore used with them
in multivariate analysis. Proximal stipe width is measured immediately after the initial flexure of
stipes. Distal stipe width is measured in the distal region of mature rhabdosomes, but proximal to
the still-growing distal extremity. Stipe divergence angle : by convention this is measured ventrally
(externally), so the wide variation seen in some species, such as P. m. koi (80°), is only a small
proportion of the total divergence angle (280-360°). Thus the coefficient of variation for this
character is misleadingly low (7) since it is inconceivable that a specimen with stipes diverging at
less than 180° would still be called an isograptid; a more appropriate value (60) is achieved by
measuring the included angle (0-80°). It should be noted that the high coefficients quoted by Cooper
(1973) were inadvertently arrived at by measuring the included angle, although the actual divergence
angle was given as an excluded (ventral) angle.

Rhabdosome astogeny and allometry

The change in rhabdosome proportions with astogeny (heterauxesis) in isograptids was discussed
by Cooper (1973, pp. 92-94). The rhabdosome grows by terminal addition of thecae. Cooper
inferred from growth stages that only the three to six most recently formed thecae at the growing
(distal) end of the stipe had not reached their full length and should be regarded as immature. Older
thecae preceding the distal six had completed their growth and measurements based on them are
free of the effects of astogeny.

We now have quantitative evidence supporting this inference. If any of the measured features
continued to grow throughout growth of the rhabdosome they should show a significant positive

318

PALAEONTOLOGY, VOLUME 29

correlation with stipe length which, up to the genetically determined maximum, changes continu-
ously by the distal addition of new thecae, and is the main contributor to allometric change.

The correlation of stipe length with other measured characters in six pseudisograptid taxa is
given in Table 1 . The only significant positive values are with proximal stipe width (in P. dumosus)
and sicula length (in P. m. manubriatus and P. m. harrisi ); most values are low or even negative.
Certainly there is no consistent pattern which one would expect if either sicula length or stipe width
increased throughout growth of the rhabdosome. P. m. manubriatus and P. dumosus are represented
by small populations and we suspect that these values, like the negative values for stipe width and
manubrium length in P. m. koi, and for manubrium width (which cannot change with growth) in
P. gracilis are due to chance. We therefore feel confident that the measured characters reflect mature
rhabdosome dimensions and are free from allometric effects.

table 1. Correlation of stipe length with sicula length, manubrium width, manubrium length, and
proximal stipe width in six pseudisograptids. Values significant at the 95 % level are in italics

N

Sicula

length

Manubrium

width

Manubrium

length

Proximal
stipe width

P. hastatus (T. S. Hall)

22

0-269

0-156

0-182

0-224

P. gracilis (Ruedemann)

18

-0-223

- 0-442

-0-079

-0-151

P. dumosus (Harris)

22

0-258

0-242

0-043

0-562

P. m. manubriatus (T. S. Hall)

13

0-640

-0-046

-0-050

0-382

P. m. koi ssp. nov.

50

-0-058

-0-008

-0-273

-0-290

P. m. harrisi ssp. nov.

30

0-391

0-306

0-052

-0-059

Statistical methods

The basic univariate statistics for each character— minimum and maximum values, mean, standard
deviation, and coefficient of variation are given in the appendix. Frequency distribution histo-
grams depict the variation for each character and provide the simplest test of whether or not a
sample represents a single population. Histograms of sicula length and manubrium size (text-fig.
14a, c) measured on specimens from Jimmy Creek, for example, suggest that two populations
are represented (P. m. koi and P. m. janus). Character correlation matrices are given in the
appendix and bivariate plots of selected characters are shown in text-figs. 15, 24, and 28. The
bivariate plots provide a convenient way of discriminating taxa in the hastatus and dumosus groups
(text-figs. 24, 28).

A more comprehensive way of showing the distribution of specimens throughout a population in
terms of their total morphologic variation is multivariate principal components analysis (PCA),
which uses all measurements on all specimens (complete data sets only). Because the variates
(character states or measurements) have various scales (e.g. stipe divergence ranges from about
270° to 360° whereas manubrium width ranges from about 0-7 to about 2-5 mm) the analysis was
based on the correlation matrix rather than the dispersion matrix.

The two major axes generally together account for about 70 % or more of the total variance in
the taxa studied by this method (P. manubriatus group, P. gracilis , P. hastatus , P. dumosus , and P.
jiangxiensis) and lower order axes have therefore not been used. A plot of the principal components
gives a more representative idea of the distribution of specimens in terms of the total morphologic
variation than any univariate or bivariate plot, and often reveals clustering. Two groups are clearly
distinguished in plots of manubriatus- like specimens from Jimmy Creek {P. m. koi and P. m. janus;
text-fig. 6) and groups can be similarly recognized in plots of the P. dumosus and P. hastatus groups

COOPER AND NI: PSEUDISOG RA PTUS

319

(text-figs. 25, 29). PCA is thus useful for taxonomic discrimination. Measurements on a single
character in different populations may overlap in range, producing a single unimodal curve and
giving the false impression of a single population; multivariate analysis helps reveal populations
and identifies the characters most useful in discriminating them.

Only five of the measured characters have been used in PCA— sicula length, manubrium width,
manubrium length, proximal stipe width, and stipe divergence angle (except for P. dumosus where
rhabdosome width, measured at the level of the base of the manubrium, was used instead). Free
proximal sicula length and manubrium angle are not used for reasons explained above, and
infradorsal sicula length is not used with manubrium length because together they become highly
dependent on sicula length. Distal stipe width also will obviously be highly dependent on proximal
stipe width and is omitted. All characters are equally weighted.

In view of the phylogenetic approach to taxonomy and classification advocated below it should
be noted that PCA is basically phenetic, i.e. there is no distinction between primitive (plesiomorphic)
and derived (apomorphic) characters. The distribution of specimens depends on their overall mor-
phology as represented by the measured characters, whereas in the evolutionary and phylogenetic
(cladist) methods emphasis is placed on selected ‘key’ (apomorphic) characters (see discussion
below). PCA is used here, however, only at the level of distinguishing population (species or
subspecies) pairs and not for dealing with large groups of taxa, for which purpose there are
better techniques available. Primitive characters will tend to falsely enhance the similarity among
specimens seen by PCA, thereby reducing the discriminatory power of the method, unless there is a
simultaneous secondary loss of two or more primitive characters in the one set of specimens that is
not taxonomically significant but due to chance (sampling) or environmental factors, etc.; PCA
would regard this as significant and group the specimens accordingly. All characters used herein
are continuous variates and such a situation is most unlikely to arise.

To obtain a measure of the degree of overlap between populations in multidimensional space a
GENSTAT non-hierarchial classification program was used. This reclassifies specimens to that class
(‘taxon’) in which they fit best. It does so by attempting to maximize the total of the Mahalanobis D2
distances between classes. A population with a considerable morphologic overlap on a second
population will have a relatively high percentage of its members reclassified into the second popu-
lation. Thus a multivariate estimate of the percentage overlap between populations is obtained.
This helps in deciding whether or not two populations are sufficiently distinct to separate as different
subspecies or species, and to which of two species an odd, morphologically intermediate specimen
should be referred. It is therefore particularly useful in the study of high variance populations such
as the manubriate isograptids.

RELATIONSHIPS, PHYLOGENY, AND CLASSIFICATION

Relationships

From the following descriptions and discussion a tentative cladogram, showing the inferred relation-
ships between taxa, can be constructed (text-fig. 4). Synapomorphies (shared derived characters) are
specified in the caption.

The entire group is characterized by the possession of a manubrium. Those species with a
weakly developed manubrium ( PP geniculatus , PP aggestus , PP menaiensis , and PP angel) are only
tentatively included, as a discrete sub-group. Of forms with a well-developed manubrium, P. hastatus
alone lacks marked outward deflection of proximal thecae and has distal thecae which differ little
from those of Isograptus\ it is thus an isograptid of I. victoriae type with a manubrium suggesting
that the I. victoriae group is the outgroup for comparison with pseudisograptids. The remaining
pseudisograptids can be split into those with advanced manubriate thecal form and those with
(primitive) simple manubriate thecal form. In the first category, one group includes Kalpinograptus
(= Apoglossograptus) and the Glossograptina which share a fully developed pseudopericalycal
proximal structure, and Apiograptus which has only a partially developed pseudopericalycal struc-
ture. If this grouping is correct, then scandency has either evolved independently in Apiograptus

320

PALAEONTOLOGY, VOLUME 29

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text-fig. 4. Stratigraphic ranges of pseudisograptid and related taxa and a cladogram showing
relationships between taxa. Shared derived characters (synapomorphies) specified by numbers:
1, presence of manubrium; 2, manubrium well developed; 3, strong outward deflection of
proximal thecae, plaiting of proximal thecae, and simple manubriate form; 4, advanced manu-
briate thecal form; 5, pseudopericalycal structure partially developed; 6, pseudopericalycal
structure fully developed; 7, expanded manubrium and shortened stipes.

and the Glossograptina or it is apomorphic for the group and has been secondarily lost in Kalpino-
graptus. A second group includes P. tan and the P. manubriatus complex; it retains the (primitive)
platycalycal structure and exhibits prothecal folds.

The second category also includes two species groups: in the first (P. dumosus s.l. and
P. jiangxiensis) the manubrium is relatively expanded and stipes diminished in size; in the second
(P. bellulus and P. gracilis) the primitive states for these features are retained.

Phylogeny. From the cladogram and stratigraphic ranges a tentative scheme of phylogenetic re-
lationships can be derived (text-fig. 5). The earliest known manubriate isograptid, P. hastatus is
also that which deviates least in morphology from isograptids of the I. victoriae lineage, previously
suggested to be ancestral to the manubriate group (Cooper 1973). An ancestor at about the level of
victoriae or maximus could have given rise to an early manubriate form by elongation of the sicula
and proximal thecae and delay in the point of upward flexure of the stipes, thus producing a simple
manubrium in an otherwise isograptid rhabdosome. A slight modification of distal thecae by Thecal
neoteny’ would have given rise to a lower distal angle of inclination and a more inclined apertural
margin. The result would have been a rhabdosome like that of P. hastatus. The strong outward
deflection of proximal thecae, characteristic of manubriate species, was a later derived character.
The I. victoriae lineage is thus tentatively taken as ancestral to the manubriate group.

The position of the geniculatus group of species is quite uncertain and the four species here
included may not comprise a natural grouping at all. With their weakly developed manubrium they
are shown to have diverged at an early stage but they bear little resemblance to early Australasian
manubriate species and may have been independently derived.

COOPER AND NI: PS E U D ISOG RA PTU S

321

All other manubriate forms are thought to have been derived from P. hastatus or a closely related
coeval form. One major branch gave rise to the P. manubriatus complex and its derivatives, and to
the Apiograptus-Kalpinograptus glossograptid group. The other branch produced P. gracilis and P.
bellulus in one fork and the dumosus-jiangxiensis group in the other fork.

The most rapid diversification took place in the early Yapeenian, a time of extreme plasticity in
the P. manubriatus complex. However, except for the glossograptines (which appear in the Darri-
wilian with Glossograptus , Cryptograptus , and Paraglossograptus) and the Llandeilo form Kalpino-
graptus, the manubriate stock had disappeared by the early Darriwilian.

Classification

There has been much recent discussion on principles and methods of biological classification and
three main approaches to the practice have emerged, two of which are based on evolutionary
relationships. The first, the cladistic method, adheres strictly to phylogeny (genealogy) whereas the
second, the evolutionary method, incorporates both phylogeny and an estimate of anagenetic
distance between taxa. Of particular interest to us here is the treatment of paraphyletic taxa (i.e. a
group that includes a common ancestor and some, but not all, of its descendants); evolutionary
taxonomists accept such groups as valid taxa whereas cladists reject them. Throughout this dis-
cussion terms and concepts used are as defined by Wiley (1981).

322

PALAEONTOLOGY, VOLUME 29

As far as the classification of graptolites is concerned, various approaches of earlier workers were
discussed by Cooper and Fortey (1982) and a plea was made to adopt a phylogenetically based
scheme. Their attempt at classification of the dichograptoids represents a first step towards such a
scheme. In this work we are dealing mainly with lower taxonomic levels but the same phylogenetic
principles apply. However, we recognize the usefulness of distinguishing and naming one class of
paraphyletic taxa — stem groups— at least as an interim measure. It is convenient, for example, to
be able to refer to the Anisograptidae, a stem group for several distinct lineages currently grouped
under Dichograptidae. In this account, Pseudisograptus is a stem group.

If our inferred phylogeny (text-fig. 5) is correct, there are several important implications for
classification and taxonomy:

1. Status of Glossograptina. Jaanusson (1960) raised Lapworth’s Family Glossograptidae to
suborder rank, stressing the ‘considerable morphological discontinuity’ which separates it from the
diplograptids. Bulman (1963, p. 408) accepted this ranking and commented that the structural
differences of both the glossograptids and diplograptids ‘from the specialised isograptids in sicula,
budding, and thecae are in my estimation so great as to eliminate this group from possible ancestry
(cf. Thomas I960)’. We are not concerned here with the relationships of the diplograptids but would
claim that from the evidence now available the morphological gap separating the glossograptids
from Pseudisograptus is much less than was formerly thought. Further, the ancestor of the glosso-
graptids is most likely to be a pseudisograptid. This means that the glossograptids, including
Kalpinogratus (following Finney 1978), plus Apiograptus (included here) form a sister group to
Pseudisograptus, and the entire Pseudisograptus- glossograptid complex is a sister group to the
remaining Isograptidae. The high ranking of the glossograptids no longer seems necessary, nor is it
desirable when the rank of its sister groups is considered; it is here suggested that it be downgraded
to family group rank and include the following genera: G/ossograptus, Paraglossograptus, ICrypto-
graptus, Lonchograptus , Nanograptus, Kalpinograptus , and Apiograptus. The key character for the
group is the presence of pseudopericalycal structure. Cryptograptus differs in several respects (Finney
1978, p. 491) but is tentatively included since it is now known to include forms with comparable
proximal structure (e.g. C. marcidus ).

2. Pseudisograptus is a paraphyletic taxon because it includes the common ancestor and some,
but not all, of its descendants (glossograptids are excluded). This seems preferable to the alternative
of establishing new genera for the gracilis-dumosus, hastatus , and angel groups which would be
necessary to maintain monophyletic taxa. Furthermore, all the genera would need their own family
group names to match the family group status of the glossograptids.

3. Going further back in ancestry, if we are correct in assuming that the I. victoriae lineage (at
about the stage of victoriae I maximus) is ancestral to the manubriate complex then, if cladist prin-
ciples are strictly applied, members of the lineage beyond this stage ( maximus , maximo diver gens,
divergens) form a sister group to that which includes the glossograptids and must be of equally high
rank; members below this stage ( lunatus , victoriae ) belong in a different group of equally high rank.
The problem is in fact circumvented by the grouping of all members of the I. victoriae lineage by
Cooper (1973) and Harris (1933) within a single species which cannot therefore be subdivided. But
the status of the group represented by I victoriae and its descendants must have rank equal to, or
higher than that of, the entire manubriate complex (including the glossograptids).

Conclusions

The glossograptids (including Kalpinograptus and Apiograptus) form a monophyletic group, here
distinguished as subfamily Glossograptinae. Its sister group is the paraphyletic Pseudisograptus, sole
occupant of the new subfamily Pseudisograptinae. The two subfamilies are grouped in the family
Glossograptidae, a monophyletic sister group to the Isograptidae which contains the sole subfamily
Isograptinaei’CMS'w Cooper and Fortey (1982) but excluding Pseudisograptus. This arrangement mini-
mizes the number of paraphyletic taxa and retains the most useful groupings of species and genera.
Corynoides and Corynites are grouped in Glossograptinae, following Finney ( 1 978).

COOPER AND NI: P S E U D / SOG RA PTU S

323

Family glossograptidae Lapworth, 1873 (emend.)

Subfamily glossograptinae Lapworth, 1873

Genera Glossograptus, Apiograptus , Kalpinograptus , Lonchograptus , Nanograptus , Paraglosso-
graptus , Corynoides , Corynites , ICryptograptus
Subfamily pseudisograptinae (subfam. nov.)

Genus Pseudisograptus
Family isograptidae Harris, 1933 (emend.)

Subfamily isograptinae

Genera Isograptus , Skiagraptus, Cardiograptus , 1 Paracardiograptus , lOncograptus

SYSTEMATIC PALAEONTOLOGY

Repositories of specimens. Abbreviations used are as follows: P, Museum of Victoria, Division of Natural
History and Anthropology, Melbourne, Australia; PR, New Zealand Geological Survey, Lower Hutt, New
Zealand; NIGP, Nanjing Institute of Geology and Palaeontology, Nanjing, China; VG, Department of
Geology, Victoria University of Wellington, New Zealand.

Fossil locality numbers cited for New Zealand are those of the New Zealand Fossil Record File.

Family glossograptidae Lapworth, 1873 (emend.)

Diagnosis (revised). Stipes reclined to scandent; initial downward growth of stipes involving at least
the first two thecal pairs; in earlier forms pronounced downward growth results in formation of a
manubrium, but in later scandent forms only the first two thecal pairs retain this downward growth.
Distal thecae are of relatively low inclination and of manubriate (or glossograptid) thecal form,
with a pronounced ventral process in later forms.

Discussion. As conceived here the Family is a broad one, but it embraces forms each of which is
thought to be more closely related to others in the group than to members of another family. It is
comprised of two subfamilies: Glossograptinae and Pseudisograptinae.

Subfamily glossograptinae Lapworth, 1873

Diagnosis. Stipes reclined to scandent, initially monoserial or monoserial throughout; proximal
structure pseudopericalycal; thecae of advanced manubriate form.

Discussion. The subfamily basically represents the Glossograptina of Jaanusson (1960) expanded
only to include Apiograptus and Kalpinograptus. If Cryptograptus is correctly included, then the
diagnosis should be emended to include forms with artus-type development, true pericalycal struc-
ture, and thecae which lack an apertural process. The presence of ‘normal’ development in C.
marcidus (Hall) (see Finney 1978) suggests that artus development (and true pericalycal structure)
in C. tricornis (Carruthers) (see Bulman 1945) was secondarily derived. The position of Bergstroemo-
graptus Finney and Chen, 1984 is unclear; it combines glossograptid features of proximal structure
with a thecal morphology which, at least superficially, resembles that of isograptids. For the time
being, it is left incertae sedis.

Subfamily pseudisograptinae subfam. nov.

Diagnosis. Stipes reclined; manubrium present; thecae of simple to advanced manubriate form;
development of isograptid type; proximal structure platycalycal; prothecal folds present in some
species.

Discussion. The subfamily contains one genus, Pseudisograptus.

Genus Pseudisograptus Beavis, 1972
[= Arienograptus Yu and Fang, 1981; ? = Xiushuigraptus Yu and Fang, 1983]

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PALAEONTOLOGY, VOLUME 29

Type species. Didymograptus caduceus var. manubriatus T. S. Hall, by original designation.

Diagnosis. As for subfamily.

Discussion. Beavis’s (1972) diagnosis was based on P. manubriatus texanus which is now known to
be a somewhat aberrant form. The above emended diagnosis therefore makes no special reference
to curvature and overlap of proximal thecae, and includes forms with no evidence of prothecal
folds. It agrees with the diagnosis of Jenkins (1982). The key feature of Pseudisograptus is the
presence of a manubrium; this feature can be regarded as a synapomorphy of the genus. The low
inclination of distal thecae also appears to be synapomorphic. Those manubriate species in which
isograptid symmetry is weak or lacking (P. tau and P. aggestus ) are here interpreted as having lost
the feature, present in their ancestors.

Arienograptus Yu and Fang, based on A. jiangxiensis (described below) is here synonymized with
Pseudisograptus. Xiushuigraptus Yu and Fang, with X. songxiensis as sole species, appears to
represent a growth stage of a species such as P. m. janus', it is tentatively placed in synonymy with
Pseudisograptus.

The genus, as employed here, contains all known manubriate isograptid species.

Species. Species and subspecies included in the genus are listed together with an indication of the main name
changes introduced here: P. m. manubriatus (T. S. Hall, 1914), P. m. koi ssp. nov. ( = P. manubriatus Forms B
and D of Cooper and McLaurin 1974 and Cooper 1979), P. m. harrisi ssp. nov., P. m. janus ssp. nov. (= P.
manubriatus Form C of Cooper and McLaurin 1974), P. m. texanus ssp. nov. ( = P. manubriatus, sensu Bulman
1968), P. bellulus sp. nov., P. dumosus (Harris, 1933) (= P. dumosus Forms A and B of Cooper 1973),
P. gracilis (Ruedemann, 1947) (= P. hastatus Form B of Cooper 1973), P. jiangxiensis (Yu and Fang, 1981)
(= P. dumosus Form C of Cooper 1973), P. tau (Harris, 1933) (= Maeandrograptus tau of previous authors),
PP. aggestus (Harris, 1933) ( = M . aggestus of Harris 1933), PP geniculatus (Skevington, 1963), P.? angel
Jenkins, 1982, and P .? menaiensis Jenkins, 1982.

These species are discussed below in the sequence that reflects related groups, rather than in alphabetical
order.

Pseudisograptus manubriatus ( T. S. Hall, 1914) ,v./.

Analysis of populations

New Zealand. The New Zealand population comes from a single locality in Jimmy Creek, Aorangi
Mine, north-west Nelson, from strata thought to span a relatively short time interval. Its end
members are so different that the average graptolite taxonomist would have no hesitation in
separating them as distinct species. Compare, for example, text-fig. 12c and bb. The specimen of
text-fig. 12c has curved stipes that are relatively narrow, of uniform width and (for isograptids)
relatively low divergence angle, and a prominent manubrium; in the specimen of text-fig. 12bb the
converse applies for each character. Furthermore, from the growth stages it is clear that the different
rhabdosome forms result from different developmental ‘pathways’ and are not the result of late
stage differences in development. On grounds of mature rhabdosome morphology and astogeny,
therefore, it would seem that the two forms represent distinct species. Certainly, the differences
between them are of the kind and order of magnitude of those generally taken as separating
graptolite species. How, then, can they be included within a single subspecies?

The basic question to be answered is do the specimens all belong to a single population or can
they be sorted into two or more populations? From inspection it is clear that the end members are
linked by intermediates but what is the frequency distribution of specimens throughout the entire
range of variation? To find out, we measured nine characters on each of the fifty-five manubriatus -
like specimens from Jimmy Creek. Apart from a small group of six specimens, here separated out
as P. janus, there is no clear evidence in the frequency distribution for any character of more than a
single population, and most are strongly unimodal indicating a single population (text-fig. 14). The
intermediate forms are more abundant than the end members for every measured character. In
the PCA plot, based on five measured characters and accounting for 88 % of the total variation.

COOPER AND NI: PS E U D I SOG RA PT U S

325

the specimens plot as a compact group with no obvious within-group clustering, as might be
expected if more than one population was present (text-fig. 6).

We conclude that, despite the wide range of rhabdosome forms present in the Jimmy Creek
population, only a single taxon is represented. It has the greatest range of variability of any
graptolite species with which we are familiar, reflected in the exceptionally high coefficients of
variation for each measured character (7-30; see Appendix).

text-fig. 6. PCA plot of specimens from Jimmy Creek, north-west Nelson, New Zealand, showing two
groups, Pseudisograptus manubriatus janus ssp. nov. and P. m. koi ssp. nov.

Australia. From inspection it was clear that the sixty measured specimens from Willey's Quarry,
Macedon, Victoria, represented a range of morphological variation as great or greater than the
material from Jimmy Creek. The measured characters were histogramed and it was immediately
obvious that two groups could be distinguished on the basis of sicula length, those with siculae
shorter than 6.5 mm (Group 1) and those with siculae longer than 6-5 mm (Group 2) (text-fig. 7);
the same two groups are also suggested by manubrium length. No unequivocal groups emerged
from a PCA plot, but when the Group 1 specimens with short siculae are distinguished on the plot
they make up a distinct group with no overlap on the Group 2 specimens with long siculae (text-
fig. 8). Thus the pattern of distribution derived from sicula length is consistent with that based on
the two major PCA axes (derived from all measured characters), strongly suggesting that two
populations are present.

Group 1, with short siculae, includes forms ranging from those that resemble Hall’s (1914, pi.
17, fig. 12) figure of the type to forms matching those referred to P. m. koi in New Zealand. Could
this group itself be comprised of more than one population? To test this possibility the same
procedure was employed. Those forms with short broad manubria, as in the type form, are readily
separated on a histogram of manubrium angle (Text-fig. 14d). On a PCA plot they form a loose

326

PALAEONTOLOGY, VOLUME 29

Willeys Quarry, entire sample (n = 58)

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text-fig. 8. PCA plot of all specimens from Willey's Quarry, Victoria. Those with short siculae
(Group 1) occupy a field with no overlap on that of specimens with long siculae (Group 2).

but largely distinct group (text-fig. 9). A few specimens (e.g. text-fig. 13c) are transitional in
morphology and could be referred to either group, suggesting an overlap between groups. Group 1
is therefore taken as comprising two adjacent or overlapping populations, here referred to P. m.
manubriatus and P. m. koi ssp. nov.

Group 2, with long siculae, appears to represent a single taxon, here recognized as P. m. harrisi
ssp. nov. with the exception of two specimens (text-fig. 13h, i) which match well with New Zealand
specimens of P. m. janus. On the PCA plot of Group 2 forms, the two specimens lie in one corner
(text-fig. 20).

COOPER AND NI: PSEUDISOGRA PTUS

327

First component (35%)

text-fig. 9. PCA plot of Group 1 specimens (short siculae) from Willey’s Quarry, Victoria.

Thus the Willey’s Quarry specimens are referred to four different pseudisograptid taxa.

The four Australasian populations recognized (P. m. manubriatus , P. in. koi , P. in. harrisi , and P.
m. j anus) are centres of clustering within a continuum representing the full morphological range of
the species, sensu lato. No clear morphological gaps separate any one population from all others;
each population is linked to at least one of its sister populations by specimens transitional in
morphology between the two. For this reason they are best regarded as subspecies rather than as
distinct species, and are interpreted as populations that had not become genetically isolated.

Pseudisograptus manubriatus manubriatus (T. S. Hall, 1914)

Plate 24, figs. 7 and 8; text-fig. 10

1914 Didymograptus caduceus var. manubriatus T. S. Hall, pp. 108-109, pi. 17, fig. 12 ( non fig. 13 =
Pseudisograptus hastatus).

1933 Isograptus manubriatus (T. S. Hall); Harris, pp. 102 104, pi. 6, fig. 1/and /;; text-figs. 41-43.

1968 Isograptus manubriatus (T. S. Hall); Skevington, fig. 2.

1974 Pseudisograptus manubriatus (T. S. Hall) Form A, Cooper and McLaurin, p. 78, fig. 1 a-d.

Identity of Pseudisograptus manubriatus. Hall (1914) established his new variety, Didymograptus caduceus
var. manubriatus var. nov. with the following statement: 'Differs from the typical form by the immense size of
the sicula, which at the point of separation of the branches is as wide as the branch itself. Thecae 10 in 1 cm.
Branches diverging at 130° to 140°, and varying from 2 to 3 mm. in width. There is considerable range in the
width of the branches, and the angle of divergence, but the great size of the sicula is remarkable. The variety
is common at the recorded localities.’ Two specimens were figured (pi. 17); that of fig. 12 is from a 'quarry in
hard blue slate, one mile west of school on road from Woodend to Macedon' and labelled 'Type’; that of
fig. 13 is from ‘similar rock Steiglitz District’, and labelled ‘Cotype’.

The specimen from Steiglitz was referred by Harris (1933, p. 23) to his new species Isograptus hastatus,
effectively establishing the specimen from Macedon as lectotype. Harris discussed the type locality and

328

PALAEONTOLOGY, VOLUME 29

text-fig. 10. Pseudisograptus manubriatus manubriatus (T. S. Hall), from Willey’s Quarry, Victoria, a, mature
rhabdosome, P 98216b; b, proposed neotype, P 103870; c, mature rhabdosome, P 42706.9; d, growth stage,
P 42706.8; e, P 103878; f, P 103877; G, growth stage, P 103874. All x 3.

concluded that it was most probably a disused quarry known as Willey's Quarry, ‘less than 1 mile west of the
main Gisborne to Macedon Road, on the southern slope of the divide, about 38| miles from Melbourne’.
This conclusion is accepted here.

Harris makes no reference to having examined Hall's ‘Type’ specimen, the whereabouts of which is now
unknown (Cooper 1973; Beavis and Beavis 1974). Efforts to locate the specimen by Museum staff have been
unsuccessful and it is now considered lost. Harris figured eight specimens, representing growth stages, from
Willey’s Quarry, and a mature specimen from an ‘isolated slab about 1 mile west of the old school site
on the Main Divide, 3 miles south of Woodend’, in his plate 6. A further four specimens from Willey’s Quarry
(his text-figs. 4 1 44) include two growth stages and two mature specimens.

Both Hall and Harris commented on the wide range of variation in rhabdosome morphology in the species,
but Hall's material, of course, included forms now ascribed to P. hastatus. Harris commented (p. Ill) that
‘the range of variation is too great to be illustrated’ but referred in his caption (p. 1 14) to varieties with long
and short ‘sicular regions’. Both varieties were said to be ‘equally common’. Stipe divergence angle was also
said to be variable.

A wide range of morphological variation is present among forms ascribed to the species. In New Zealand
three informal forms were recognized by Cooper (1979) and Cooper and McLaurin (1974), all of which were
thought to be distinct from the ‘type form’.

In the present work, four subspecies are recognized among material from Willey's Quarry and a fifth in
Texas. The identity of the nominate subspecies, P. m. manubriatus , is in some doubt because Hall’s figure
(1914, pi. 17, fig. 12) does not show sufficient morphological detail; it also appears to represent a specimen
lying within one subspecies but near the morphological boundary with a neighbouring subspecies. This doubt
can only be removed by designation of a neotype, and this course is proposed here.

EXPLANATION OF PLATE 24

Figs. 1-6, 9-12. Pseudisograptus manubriatus koi ssp. nov. from the Yapeenian of Jimmy Creek, Aorangi
Mine, north-west Nelson, New Zealand. 1, PR 527, x4. 2, growth stage, PR 411, x6-5. 3, PR 508, x4.
4, PR 354, x4. 5, growth stage, PR 561, x4. 6, PR 348, x4. 9, PR 350, x4. 10, PR 355, x4. 11, PR 375,
x4. 12, PR 530, x4. The specimens of figs. 12 and 13 correspond to Form D of Cooper (1979), all others
correspond to Form B.

Figs. 7, 8. P. m. manubriatus (T. S. Hall) from the Yapeenian of Willey’s Quarry, Macedon, Victoria. 7,
neotype, P 103870, x4. 8, topotype, P 42706.9, x 3-75.

PLATE 24

COOPER and NI, Pseudisograptus

330

PALAEONTOLOGY, VOLUME 29

Neotype. Specimen P 103870 from Willey’s Quarry, Macedon, Victoria, is here proposed as neotype (text-fig.
10b). A detailed comparison with Hall’s figure is not possible because the figure lacks morphological detail;
for example, the free proximal portions of the sicula and first theca do not show in Hall’s figure and no details
of rhabdosome structure are visible. However, in general outline the proposed neotype is a good match, except
that the manubrium appears to be somewhat shorter and broader. Of the four subspecies recognized at
Willey’s Quarry, Hall's specimen most closely matches that of which the proposed neotype is clearly a member.
It also accords with the prevailing concept of the ‘type form’ of P. manubriatus (Bulman 1968; Cooper and
McLaurin 1974, Form A) in so far as rhabdosome outline is concerned. Beavis (1972) differed, claiming that
the Texan specimen ‘differs in several respects from the Victorian material, notably in the greater length and
narrowness, relatively of the thecae; the two forms may be provincial variants or the differences may reflect
the degree of compression, since the Texan specimens are in high relief’. However, from the topotypes figured
here it can be seen that the differences specified are minimal, although it is conceded that on other grounds
(proximal rhabdosome structure) the Texan material can be accorded separate subspecific status.

The proposed neotype is the only topotype specimen known to us in which the proximal region is preserved
in sufficient relief to clearly define the growth paths (at least distally) of proximal thecae, a feature crucial to
its distinction from the Texan subspecies. The neotype is preserved in obverse view.

Measured material. Fifteen specimens: P 98216a (transient to P. m. koi), 98216b, 98223c, 98226a-d, 42706,
103870, 103877, 103878, and four other specimens, together with several incomplete or poorly preserved
specimens, from Willey's Quarry, Macedon, Victoria.

Horizon. Yapeenian; Willey’s Quarry, Chinamen’s Creek, and several other localities in Victoria.

Description. The rhabdosome is relatively small and compact; the manubrium is short and broad. The base of
the manubrium makes a sharp angle with the dorsal stipe margin and in some specimens, such as the neotype
(text-fig. 10b), it is clear that the dorsal stipe margin overlaps laterally on to the manubrium, growing around
in a loop in the manner described by Cooper and McLaurin (1974, p. 80) in P. manubriatus , and here in P. m.
janus.

The sicula averages 4-8 mm (range 4-3-5-9 mm) in length, its free proximal portion averaging 1 -2 mm (range
0-8-2 0 mm; V = 28). Forms with long siculae tend to be those with long free proximal portions (see
Appendix). Manubrium length is also variable (0- 5-0-9 mm; V = 27), averaging 0-7 mm; manubrium width
averages T9 mm (range T7-2-4 mm). The angle subtended by the manubrium shoulders ranges from 90° to
130°. Some details of proximal structure are seen in the neotype which is preserved in partial relief. The two
thecal series are arranged symmetrically on either side of the rhabdosome midline and do not overlap each
other as in the specimen from Texas described by Bulman (1968). Proximal thecae are long and recurved near
their distal ends. The manubrium is comprised of the proximal portions of at least the first five pairs of thecae.

Stipes diverge from 310 to 335° and have generally straight dorsal margins which, in some specimens, show
undulations suggesting the presence of prothecal folds. They reach 13 mm in length, are 2.6 mm (range 2-2-
3-2 mm) wide proximally, and 3-1 mm (range 2-5-3 8 mm) wide distally. Stipe width is significantly negatively
correlated with manubrium length and positively correlated with stipe divergence angle; forms with broad
stipes tend to have more highly diverging stipes and shorter manubria.

Variation in stipe width does not interfere with the smoothly rounded ventral rhabdosome profile. Increase
in stipe width is accommodated by a displacement of the dorsal stipe margin towards the rhabdosome midline
(and encroachment on to the manubrium). In a few specimens there are considerable irregularities in the line
of the dorsal stipe margin but these are not reflected in the ventral stipe margin; the apertural margins of
thecae are aligned along a smooth curving line.

Thecae are spaced about five in 5 mm. They have a highly inclined apertural margin extended into a ventral
process (advanced manubriate form).

Discussion. The subspecies forms a small group within the Willey’s Quarry material. Modal forms
are readily distinguished from the other subspecies, particularly P. m. harrisi and P. m. janus, by
their short squat manubria (text-fig. 14d). In Willey’s Quarry there are a few specimens that have a
relatively long sicula and/or a deep infradorsal region; they are transitional in morphology towards
P. m. koi or P. m. harrisi.

In gross rhabdosome morphology P. m. texanus closely matches the nominate subspecies;
the distinction lies in their proximal structure. As seen in the neotype the two thecal series are
symmetrically arranged on either side of the rhabdosome midline and are not superposed as in
P. m. texanus.

COOPER AND NI: P S EU D I SOG RA PTU S

331

Pseudisograptus manubriatus harrisi ssp. nov.

Plate 25, figs. 9 and 13; text-fig. 1 1

1933 Isograptus manubriatus (T. S. Hall) ( pars ); Harris, pp. 102-104, ?pl. 6, fig. lb, g , i; text-fig. 44
(non pi. 6, fig. 1/, /;; text-figs. 41-43 = P. manubriatus manubriatus ; non pi. 6, fig. la, c, d, e, ?
= P. m. koi).

Holotype. P 98222 from Willey’s Quarry, Macedon, Victoria.

Measured material. Thirty-four specimens: P 42706, 98212, 98214, 98215, 98218, 98220a, 98220b, 98221, 98222,
98224, 98225a, 98229, 98217, 103880, 103881 and nineteen other specimens, from Willey’s Quarry, Macedon,
Victoria.

Horizon. Yapeenian.

Name. After W. M. Harris of Victoria, the first worker to elucidate relationships among the Victorian
isograptids.

Description. The rhabdosome is relatively large and is variable in shape, ranging from an open V-shape to
forms with nearly parallel stipes. The manubrium is generally large and wedge-shaped; its top is defined by a
destinct break in slope from the free proximal portion of the sicula and th 1 1 . In forms with nearly parallel
stipes the proximal portions of the stipes encroach upon the manubrium, reducing its apparent overall size
(text-fig. 1 1 h) The apex of the sicula is generally clearly marked, the nema being a thin thread in most
specimens; in a few it is stout and passes gradually rather than abruptly into the sicula apex.

The sicula averages 81 (range 6-8 10 0 mm) in length, its free proximal portion averaging 21 mm but

text-fig. II. Pseudisograptus manubriatus harrisi ssp. nov., from Willey’s Quarry, Victoria. A, holotype,
P 98222; b, P 103880; c, specimen transitional towards P. m. janus and with pronounced prothecal folding,
P 98225a; d, specimen transitional towards P. m. janus, P 103886; E, immature stage, P 98220a; F, P 103883e;
G, P 103883d; h, P 98221; i, immature stage, P 98220. All x 3.

332

PALAEONTOLOGY, VOLUME 29

varying widely (1-4 mm; V = 35). Forms with long siculae tend to have long free proximal portions. The
manubrium length also varies widely, averaging 2-1 mm (range 1 -3 mm; V = 24); manubrium width is 1-9
mm (range 1 -2-2-4 mm). The angle subtended by the manubrium is 37-46° in most specimens. Structure of
the manubrium is unknown. Interthecal septa can be traced a short distance from the ventral margin in the
proximal region of the rhabdosome and suggest that the structure resembles that in P. m. manubriatus, with
no marked thecal curvature and overlap of thecal series as in P. m. texanus. The infradorsal region is long
and gives a ‘deep’ aspect to the proximal region. Infradorsal sicula length averages 3-7 mm.

Stipes in most specimens diverge at 320-330° and are either straight or have a slight dorsally-convex
curvature. Undulations of the dorsal stipe margin suggest that prothecal folds are irregularly developed. Stipes
reach 19 mm long, are 2-9 mm (range 2-4-3-4 mm) wide proximally and 3-1 mm (range 2-6-4-5 mm) wide
distally. Distal stipe width is significantly correlated with manubrium length: forms with high distal stipe
width tend to have shorter manubria (see Appendix). In most specimens the intersection between the
manubrium shoulder and dorsal stipe margin is sharp and acutely angled.

Thecae are spaced nine or ten in 10 mm. They are of advanced manubriate form with a highly inclined
apertural margin extended into a ventral process.

Discussion. The chief distinguishing features of the subspecies are the heavy, highly diverging stipes
and large rhabdosome, the extended infradorsal region, and particularly the long sicula. It varies
considerably in most characters, particularly manubrium width (V = 16), length (V = 24), free
proximal sicula length (V = 35), and distal stipe width (V — 17) resembling P. m. koi in this respect.
At first glance the specimens sometimes appear to be tectonically stretched members of other forms,
such as P. m. koi. However, many slabs are available with randomly oriented specimens in which
tectonic stretching would be immediately apparent; the effects of such distortion at Willey’s Quarry,
with the exception of a few slabs (not used), are regarded as not significant.

From P. m. koi , the subspecies is distinguished by its much longer sicula and greater infradorsal
length (text-fig. 14a, e). P. m.janus has a generally larger manubrium and shorter infradorsal length
(text-fig. 14c, e). From P. m. manubriatus and P. m. texanus the subspecies is readily distinguished
by its larger manubrium and longer sicula (text-fig. 14a, c). P. m. harrisi is the most common form
at Willey’s Quarry, and is clearly represented among Harris’s material by his text-fig. 44. Specimens
of his pi. 6. figs. 16, g, i are tentatively included; the manubrium of the mature specimen (fig. If) is
obscured and its identity is uncertain. The subspecies is unknown outside Victoria.

Pseudisograptus manubriatus koi ssp. nov.

Plate 24, figs. 1-6, 9-12; Plate 25, figs. 3 and 4; text-figs. 12 and 13a-g, j

1973 Isograptus manubriatus (T. S. Hall) (pars ); Cooper, pp. 84-88, text-fig. 22 a-g, l-n , p (non text-
fig. 22h-k = P. m.janus ; non text-fig. 22o, q = P. m. manubriatus).

1974 Isograptus manubriatus (T. S. Hall); Tsai, p. 94, pi. 9, figs. 11-15 (non figs. 7-10); text-fig. 29.

1979 Pseudisograptus manubriatus (T. S. Hall) Forms B and D, Cooper, pp. 78-79, pi. 15, figs. a-c,f,

g ; text-fig. 60a, 6, d (non pi. 15, fig. /;; text-fig. 60c = P. m. janus).

Holotype. PR 508, from Jimmy Creek, north-west Nelson, New Zealand (text-fig. 12g).

EXPLANATION OF PLATE 25

Figs. 1, 6. Pseudisograptus jiangxiensis (Yu and Fang). 1, developmental stage, PR 564, x6-5. 6, immature
rhabdosome, PR 410, x6-5.

Figs. 2, 7. P. dumosus (Harris). 2, Form B, PR 414, x 5-3. 7, Form A, P 103885, x 6-5.

Figs. 3, 4. P. manubriatus koi ssp. nov. Growth stages, PR 567 and PR 563, x 6-5.

Figs. 5,8,10-12. P. m.janus ssp. nov. 5, PR 420, x 6-5. 8, PR 403, x 4. 10, PR 420, x4. 11, PR 533, x4. 12,
immature rhabdosome, PR 562, x4-4.

Figs. 9, 13. P. m. harrisi ssp. nov. 9, P 103881, x 3-3. 13, P 103883b, x 3-3.

Figs. 1-6, 8, 10-12, from the Yapeenian of Jimmy Creek, Aorangi Mine, north-west Nelson, New Zealand.
Figs. 7, 9, 13, from the Yapeenian of Willey’s Quarry, Macedon, Victoria.

PLATE 25

COOPER and NI, Pseudisograptus

334

PALAEONTOLOGY, VOLUME 29

Measured material. Sixty specimens: PR 9-13, 311, 317, 319, 321, 324, 330, 348-350, 352, 355, 360, 363, 367,
375, 380-382, 385, 394, 395, 398, 399, 404, 405, 407, 408, 411, 416, 417, 419, 426- 428, 430, 431, 434, 508-51 1,
515-524, 526-528, 530, from Jimmy Creek, north-west Nelson, New Zealand.

Horizon. Yapeenian in New Zealand and Victoria.

Name. Koi , a spike-shaped Maori digging tool, alluding to the spike-shape of the free proximal portion of the
sicula and first theca.

Description. The sub-species displays extreme morphologic variation. The rhabdosome is relatively large and
ranges from a wide open U-shape to forcipiform with parallel or even converging stipes. The manubrium is
wedge-shaped and generally prominent, but in forms with parallel stipes it is partly obscured by the base of
the stipes. The top of the manubrium is generally marked by a distinct break in slope from the free proximal
portion of the sicula and th 1 1 . The apex of the sicula is sometimes difficult to distinguish from the base of the
nema (see p. 315). The nema is stout and up to several centimetres long; a narrow strip of peridermal film
adheres to the side in some specimens and in one the nema is forked (text-fig. 12m).

The sicula averages 5-4 mm (range 45-6-2 mm) in length, its free proximal portion averaging 1-5 mm (range
10-2-3 mm). The manubrium averages 1 -6 mm (range 0-7-2-6 mm) in length and 1 -5 mm (range 0-7-21 mm)
in width. The angle between its shoulders is 40-50 in most specimens (text-fig. 14d). Manubrium width is
significantly correlated (0 49) with manubrium length; where manubria are wide they tend also to be long
(text-fig. 15a). Few details of proximal structure can be interpreted reliably from the flattened material, but
proximal thecae of the two thecal series appear to be symmetrically arranged about the bilateral plane (as in
P. m. manubriatus and P. m. j anus) rather than overlapping (as in P. m. texanus).

Stipes range widely in divergence angle (280-360°) and curvature (from straight to strongly curved) (text-
fig. 12). In forms with low stipe divergence angle (text-fig. 12a) the base of the manubrium generally passes
smoothly into the dorsal stipe margin. In forms with high stipe divergence, the dorsal stipe margin commonly
grows around in a loop, overlapping the base of the manubrium (Cooper and McLaurin 1974, p. 80). This
has the effect of reducing the apparent width of the manubrium and increasing proximal stipe width; indeed
stipe divergence angle has significant negative correlation with manubrium width ( — 0-664) and significant
positive correlation with proximal stipe width (0-721) (text-fig. 15b).

Stipes grow up to 15 mm long. In forms with straight stipes, stipe width is generally greatest at about mid
stipe (where the ‘distal’ stipe measurement was made) and tapers slightly both proximally and distally; in
forms with curved stipes, stipe width is approximately uniform. The result is that the ventral rhabdosome
margin is always curved, whether or not the dorsal stipe margins are curved.

Thecae are extremely long; distal thecae are of low inclination (20-30°) and of advanced manubriate form.
Apertural margins are highly inclined to the stipe axis and each bears a prominent ventral process. Thecal
spacing is 5 0-6-5 in 5 mm.

Growth stages are distinctive, passing through a characteristic dumb-bell-shaped stage with the proximal
portions of the sicula and thl 1 protruding prominently.

A few specimens, particularly those with wide open-shaped rhabdosomes, show a slight proximal a sym-
metry; the bilateral plane of symmetry is deflected towards one side (presumably the stipe1 side) and there is a
consequent weakening of the isograptid symmetry (e.g. text-fig. 12b, g). At its extreme, this tendency results
in the complete loss of isograptid symmetry and acquisition of maeandrograptid symmetry. One specimen
with maeandrograptid symmetry (text-fig. 12d) also differs from most other members of the population in the
low inclination of its proximal thecae. In these features it approaches P. tau (Flarris) and suggests an origin
for that species. The specimen is linked with other members of the population via forms with proximal thecae
of low inclination (text-fig. 12b).

text-fig. 12. Pseudisograptus manubriatus koi ssp. nov., from Jimmy Creek, north-west Nelson, New Zealand.
A selection of rhabdosomes to show the range in rhabdosome form, a, PR 354; b, PR 319; c, PR 355; d,
specimen with maeandrograptid symmetry, PR 554; e and F, growth stages, PR 567 and PR 563; G, holotype,
PR 508; h, PR 417; i and j, immature specimens, PR 9 and PR 356; k, PR 515; l, PR 527; m and n, growth
stages, PR 582 with branching nema and PR 418; o, PR 348; P, specimen with longest stipes observed, PR
524; q, PR 550; r, PR 531; s, PR 350; t, PR 581; u, PR 578; v, PR 399; w, PR 370; x, growth stage, PR 560;
y, PR 13; z, PR 367; aa, PR 428; bb, PR 375; cc, PR 556. Growth stages match mature forms as follows: i, J,
and n represent a relatively open rhabdosome, such as k; e, f, and t represent the typical (modal) form, such
as w; m represents a strongly reclined form, such as y; u and x represent a form with parallel stipes, such as b.

All x 3.

COOPER AND NI: P S EU D I SO G RA PTU S

335

336

PALAEONTOLOGY, VOLUME 29

text-fig. 13. Pseudisograptus manubriatus koi ssp. nov. and P. m. j anus ssp. nov., from Willey’s Quarry,
Victoria, a-g and j, P. m. koi: a, P 103879; b, specimen transitional towards P. m.janus , P 103882; c, specimen
transitional towards P. in. manubriatus , P 98216a; d and e, immature specimens P 103874.1 and P 103876; f,
growth stage, P 42706.4; g, P 103875; j, P 103873. Hand i, P. m.janus: h, P 103872; i, P 103871. All x 3.

Fifteen specimens from Willey’s Quarry, Victoria, lie within the range of the Jimmy Creek material in all
measured characters, the mean value of each character agreeing well in the two localities. The Victoria
specimens show a similarly wide morphological spread but the extreme members (i.e. Form D of Cooper
1979, and the wide open U-shaped forms) are not present (text-fig. 13a-g and j). However, a larger sample
population from Willey’s Quarry would be likely to include a wider morphologic range than that shown by the
specimens to hand.

EXPLANATION OF PLATE 26

Figs. 1 -7. Pseudisograptus manubriatus janus spp. nov., from the Ningkuo Formation, Fentoushan, Jiangshan,
Zhejiang Province, China. 1, holotype, reverse view, NIGP 84733, x 12. 2, proximal part of manubrium
showing origins of th 1 -, th21, and t h 3 1 , reverse view, NIGP 84736, x 50. 3, same, obverse/lateral view of
manubrium (stipe2 side) showing envelopment of earlier thecae by th32, x 25. 4, detail of base of manubrium
of holotype on stipe2 side, NIGP 84733, x 15. 5, proximal part of manubrium, obverse view, showing
strongly impressed growth rings (normal to axis of growth) on the sicula and the envelopment of earlier
thecae by thd1, th32, and th42, NIGP 84736, x 25. 6, same, detail in lateral view of the origin, prothecal
fold, and prothecal invagination of t h 3 1 , x 70. 7, same, apical view showing ’crossing canal’ formed by
thl2, and broken sicula and th 1 1 , x 30.

Fig. 8, Pseudisograptus bellulus sp. nov., from the same locality, but about 1 m higher in section. Rhabdosome
complete except for apical portion of sicula and thl *, lit from below to show thecal outlines, NIGP 84735,
x 12.

PLATE 26

COOPER and NI, Pseudisograptus

338

PALAEONTOLOGY, VOLUME 29

Discussion. With its wide range of morphological variation (discussed above) it is not surprising
that peripheral members of the subspecies approach sister subspecies in morphology. The distinction
from P. m.janus is discussed with that form. In the Willey’s Quarry material the subspecies is most
easily distinguished from P. m. manubriatus by the proportions of its manubrium, reflected in
the manubrium angle (text-fig. 14d). From P. m. harrisi it is distinguished by its shorter sicula
length (text-fig. 14a) and ’shallower’ proximal region, as reflected in its shorter infradorsal length
(text-fig. 14e).

P manubnatus manubnatus

Free sicular length (mm)

Manubnum length * width (mm)

10 20 30 40 50 60 70 80 90 100 110 120 130 140 150

Manubnum angle (degrees)

COOPER AND NI: P S EU D / SOG RA PT U S

339

The range of forms figured by Tsai (1974, pi. 9, figs. 11-15, non figs. 7-10) from the Isograptus
gibberulus (I. victoriae ) Zone of Kazakhstan matches the Nelson forms well, and they are here
included in the subspecies.

Pseudisograptus manubriatus janus ssp. nov.

Plate 25, figs. 5, 8, 10 12; Plate 26, tigs. 1-7; Plate 27; text-figs. 13h, i, 16, 17

1973 Isograptus manubriatus (T. S. Hall) s.l. ( pars ); Cooper, pp. 84-88, text-fig. 22h-k (non text-fig.
22 a-g, l-q).

77777A

P manubriatus manubnatus

_JZZZL_

2 / / A -

Proximal stipe width (mm)

Stipe divergence angle (degrees)

text-fig. 14. Frequency histograms for Pseudisograptus
manubriatus subspecies of a, sicular length; b, free proximal
sicular length; c, manubrium size; d, manubrium angle; e,
infradorsal length; f, proximal stipe width; and G, stipe
divergence angle. Localities (J.C., Jimmy Creek, north-west
Nelson, New Zealand; W.Q., Willey’s Quarry, Victoria) and
numbers of specimens measured are given in parentheses.

340

PALAEONTOLOGY, VOLUME 29

1974 Pseudisograptus manubriatus (T. S. Hall) s.l. Form C, Cooper and McLaurin, pp. 77-80, text-
fig. le-g (non text-fig. 1 a-d).

1979 Pseudisograptus manubriatus (T. S. Hall) sd. Form C, Cooper and McLaurin; Cooper, pp. 78-
79, pi. 15, fig. h; text-fig. 60c.

Holotvpe. Specimen NIGP 84733 (text-fig. 17f) from the Ningkuo Formation at Fentoushan, near Jiangshan,
Zhejiang Province, China.

Material. Six measured specimens: PR 10, 340, 402, 403, 420, 533, and several immature specimens and growth
stages, all flattened, from loc. S2/f540 of Cooper (1979, p. 97), Jimmy Creek, north-west Nelson, New
Zealand; two specimens, P 103871, 103872, from Willey’s Quarry, Macedon, Victoria, similarly flattened; eight
specimens, NIGP 84731 84734, 84736-84739, from Fentoushan, near Jiangshan, Zhejiang Province, China,
pyritized and preserved in full relief in shale. The Chinese material is preserved as an internal cast and reveals
growth line details of the internal surface of the rhabdosome.

Horizon. The New Zealand and Victorian material is from the Yapeenian. The Chinese material is from
horizons 9 and I I in the section measured by Han Nairen et at. (1984) in the Ningkuo Formation, Fentoushan
Section, near Jiangshan; it is associated with Pseudotrigonograptus ensiformis and (at horizon 1 1 only) Cardio-
graptus ampins and Didymograptus hirundo , equivalent to Yapeenian in age.

Name. Janus the Roman God with two faces, alluding to the different appearance of obverse and reverse
aspects.

Description. The rhabdosome is large and V-shaped and resembles the V-shaped forms of P. manubriatus s.l.
The sicula is very long, averaging 7-4 mm (range 6-2-8-6 mm) and the free proximal portion averages T6 mm
(range 10-2-5 mm). The apex of the sicula passes into a stout nema which sometimes has a narrow adhering

3 .0 r

E

E

2.5 -
2.0 -

1.5 -
1.0 -

0

A

i i i_

1 .0 2.0 3.0

manubrium length (mm)

3.5
1 3.0

40

2 5 -

2.0 -

1.5 -

B

260

280

300 320

Stipe divergence angle

340

360

text-fig. 15. Pseudisograptus manubriatus koi ssp. nov. from Jimmy Creek, north-west Nelson, New Zealand.
A, manubrium width plotted against manubrium height, showing weak (but significant) positive correlation
(r = 0-490); b. proximal stipe width plotted against stipe divergence angle for fifty specimens, showing moder-
ate positive correlation (r = 0-721).

EXPLANATION OF PLATE 27

Figs. 1-9. Pseudisograptus manubriatus janus ssp. nov., from the Ningkuo Formation, Fengzu, Jiangshan,
Zhejiang Province, China. 1, proximal part of manubrium, reverse view, NIGP 84734. x25. 2, specimen in
reverse view but in which the proximal portion has broken away to reveal impression of obverse side, NIGP
84731, x 13. 3, detail of the origin, prothecal invagination, and lateral ‘flange’ of th4L NIGP 84734, x 65.
4, lateral/reverse view of proximal part of manubrium showing origins of th22, th32, and th42, NIGP 84734,
x25. 5, complete specimen, the manubrium of which was removed and is shown in figs. 1, 3, 4, 7, and 8,
reverse view, NIGP 84734, x 16. 6, growth stage, obverse view, NIGP 84732, x 12. 7, detail of origin of
t h 3 1 , lateral view, NIGP 84734, x 55. 8, same, lateral view of manubrium, x 25. 9, lateral/reverse view
showing origin of th2 1 and the continuity of its growth (on right-hand side) around the prothecal invagina-
tion, NIGP 84736, x 120.

PLATE 27

COOPER and NI, Pseudisograptus

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PALAEONTOLOGY, VOLUME 29

strip of periderm as in P. m. koi. The manubrium is massive and shaped like a narrow wedge, averaging
2-2 mm (range 2-0 -2-5 mm) wide and 3-3 mm (range 2-8-3-7 mm) long.

The stipes are sharply flexed and straight, reach 9-5 mm in length, and diverge at 290° (range 267-300 ). In
a few specimens (text-fig. 16n) the dorsal stipe margin appears to grow around in a loop and recross its earlier
path, as in P. m. koi. They are widest in their mid regions where they average 2-3 mm (range 2- 1 -2-8 mm);
proximally they average 2-2 mm (range 1 -9-2-5 mm). The dorsal stipe margins of some specimens show
undulations suggestive of prothecal folds, irregularly developed.

Form and inclination of distal thecae are like those of P. m. koi. Thecae are spaced about five in 5 mm.

Growth stages are distinctive and readily distinguished from those of the coeval P. m. koi by their long
sicula and gradually expanding manubrium.

text-fig. 16. Pseudisograptus manubriatus janus ssp. nov. b from Fentoushan, China; all others from Jimmy
Creek, north-west Nelson, New Zealand, a-j, growth series: a, PR 434; b, Z8; c, PR 575; d, PR 558; e, PR
389; f, PR 542; G, PR 572; h, PR 538; i, PR 576; j, PR 562; k, specimen transitional towards P. m. koi , PR
402; l, largest specimen, PR 420; m, PR 533; N, PR 10; o, PR 340. All x 3.

Description of Chinese material— rhabdosome morphology. In the most advanced growth stage (text-fig. 17f)
the manubrium is massive and stipes are barely developed. The specimen also shows the proximal, free
portions of the sicula and th 1 1 . The sicula is at least 8 mm long, and 0-6 mm wide at the aperture. The sicula
apex is not well defined as the sicula grades into the nema. The origin of thl 1 is also not clear but is high on
the sicula, at least 1 mm above thl2 and the top of the manubrium. Theca l1 grows down in contact with the
sicula, the apertural regions of the two forming a symmetrical pair. Thl1 is 7-5 mm long and of similar
apertural width to the sicula.

The massive wedge-shaped manubrium varies in size and proportion among the four relatively mature
unflattened specimens available. In the largest of these (text-fig. 17f, holotype) it measures 2-8 mm in length
and about 2T mm in width, and incorporates the proximal portions of the first seven or eight pairs of thecae.

COOPER AND NI: P S E U D ISOG R A PTU S

343

text-fig. 17. Pseudisograptus manubriatus janus ssp. nov., from Ningkuo Formation, Fentoushan, near Jiang-
shan, China, a-c, NIGP 84734: a, detail of manubrium clearly showing prothecal invaginations and initial
upward growth of thl2, x 15; b, complete specimen in reverse view, x 10; c, obverse/lateral view showing
continuity of growth around prothecal invagination for th3 1 and th4x, x 15. D, growth stage, NIGP 84732,
x 10; e, reverse view, obverse impression revealed where proximal portion has broken away, NIGP 84731,
x 10; f, holotype, reverse view, NIGP 84733, x 10; g, growth stage, NIGP 84739, x 10. h-k, NIGP 84736: h,
growth stage similar to that of d, obverse view, showing envelopment of thl2 and th22 by th32, x 10; i,
obverse/lateral view (stipe1 side) of proximal part of manubrium, x 15; j, reverse view of same, x 15; k,

obverse/lateral view (stipe2 side), x 15.

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PALAEONTOLOGY, VOLUME 29

The manubria of other rhabdosomes are smaller and incorporate fewer thecae. Variation in the angle enclosed
by the shoulders of the manubrium and in other proportions is best observed from the figures (text-fig. 17a-
k). The obverse and reverse aspects of the manubrium differ to a remarkable degree. In obverse aspect the
first three pairs of thecae grow down parallel to the sicula, flexing sharply outward near their distal ends. The
fourth pair overlap the third pair and grow in towards the sicula (text-fig. 17k) before also swinging outwards
to form part of the diverging reclined stipes. Growth lines on the sicula lie approximately normal to the
growth axis whereas growth lines on all early thecae are strongly inclined to the growth axis, indicating that
their apertures were directed away from the sicula throughout their development.

On the reverse side of the rhabdosome the growth paths of th2 1 , th22, th3 1 , t h 3 2 , and (in holotype only)
th4 1 completely overlap those of earlier thecae until near their distal ends, where they swing sharply away
from the rhabdosome’s midline and clearly reveal their plaited arrangement (text-fig. 17f). As a consequence,
thecae are strongly flattened in cross-section and the manubrium has a triangular profile (text-fig. 19c).
Rhabdosomal growth stages have the characteristic dumb-bell outline (text-fig. 17d, g) of manubriate isograp-
tids, and closely resemble those of flattened specimens here referred to the species. As on the obverse side,
growth lines are strongly inclined to the thecal growth axis.

The junction between the two thecal series (i.e. between th32 and th3 1 or th4') is straight and lies more or
less in the rhabdosome's bilateral plane, as in P. manubriatus s.l., but unlike P. m. texanus in which the line of
junction is strongly displaced to the stipe1 side (Bulman 1968, fig. 1).

Thecal apertures are not well preserved but, from outline impressions, had a pronounced ventral process.

The stipes are barely developed, even in the most mature specimen (text-fig. 17f); their initial angle of
divergence can be estimated at about 310-320°.

Proximal structure and development. Development is of isograptid type and dextral mode. Thl2 originates on
thl1, about I mm down and on its left-hand side (text-fig. 17a, b, f, j). It grows initially up and across thl1
and the sicula before growing down on the right-hand (stipe2) side of the rhabdosome. It is thus left-handed
in origin and dextral in mode of development in the sense of Cooper and Fortey (1982, pp. 173-174),
resembling Dicranograptus and the later diplograptids (Bulman 1970, pp. V78-81). It gives rise to tlG1 which
grows across to the stipe1 side and down. The downward growth is interrupted by a deep invagination in the
dorsal wall, forming a ‘recumbent' fold in the protheca (text-fig. 17c, i), following which the theca rapidly
expands to extend well across the rhabdosome midline on the reverse side (text-fig. 17j).

TIG1 arises on the right-hand side of th2 1 (i.e. on the reverse side of the rhabdosome) and immediately
develops a prothecal fold with a deep invagination. It expands rapidly to envelope th2 1 completely on the
reverse side, the fuselli reaching to the midline of the rhabdosome.

Thd1 arises on the dorsal side of th3 1 (i.e. in the normal position) and immediately forms a similar prothecal
fold to that of th3 1 . It expands rapidly and soon completely envelops tlG1 on the obverse side, even encroaching
on to th2 1 in one specimen (text-fig. 17i). This theca thus overlaps earlier thecae, but on the opposite side of
the rhabdosome to that of its predecessors. On the reverse side of the rhabdosome it either grows down beside
th3 1 (text-fig. 17b, e) or eventually overlaps it completely (text-fig. 17f).

We have no detailed growthline data on the development of th5x and th6 1 but their prothecal folds appear
to be less pronounced than those of preceding thecae. In text-fig. 17a, b, and e the downward growth of th5 1
is brief before it swings around to become part of the upward growing and diverging stipe1. In text-fig. 17b,
th6 1 commences its upward growth almost immediately after its origin. It is thus the last theca on the stipe1
side to form part of the manubrium; subsequent thecae grow out along the stipe for their entire length.
However, in text-fig. 17f the downward growth of early thecae prior to their outward deflection is more
pronounced, and more thecae become incorporated in the manubrium. Thus th6 1 and probably th7 1 grow
initially downwards, as part of the manubrium before bending sharply upwards.

In the axillary region, where the dorsal stipe margin joins the shoulder of the manubrium, there is a lateral
overlap of thecae.

In the holotype (text-fig. I7f) the first upward growing theca on the stipe1 side (th8‘) appears to originate
on the right-hand side of its parent th7 1 (i.e. on the reverse side of the rhabdosome); it laps on to the prothecal
portion of th6 1 in its upward growth. The dorsal stipe margin thus traces a loop, growing around and
recrossing the line of its earlier path, a feature noted by Cooper and McLaurin (1974, p. 80).

On the stipe2 side of the rhabdosome th22 arises on the dorsal side of thl2, forms a small prothecal fold
with a deep invagination, then rapidly expands to completely envelope thl2 and reach across to the rhabdo-
some’s midline (text-fig. 17a, j). Th32 similarly arises on the dorsal side of t h 2 2 , forms a prothecal fold with
deep invagination, and expands rapidly to completely envelope th22, after which it grows down in contact
with th3 1 on the reverse side of the rhabdosome. The sicula, thl 1 , thl2, th2*, and th22 are thus all completely

COOPER AND NI: P S EU D I SOG RA PTU S

345

enveloped on the reverse side of the rhabdosome by the pair th3 1 and t h 3 2 . In the holotype th32 is eventually
joined by th4 1 and this pair together overlap all earlier thecae.

Th42, like its opposite number th4', arises with a prothecal fold on the dorsal side of its parent theca and
then expands rapidly on the obverse side of the rhabdosome to eventually completely overlap th32. On the
reverse side it grows down in contact with th32.

text-fig. 18. Thecal diagram for Pseud-
isograptus manubriatus janus ssp. nov.,
based on specimens from the Ningkuo
Formation, Fentoushan, near Jiangshan,
China.

The origins of th52 and th62 are not well preserved in any specimens but, from the specimen of text-fig. 17f,
they are assumed to be essentially like that of their opposite numbers, th5 1 and th6! . In this same specimen,
th72 is the last theca with a significantly downward growing component. Only a fragment of the proximal
portion of th82 is preserved but it appears to arise on the obverse side of the rhabdosome (i.e. right-handedly)
as does its counterpart, th8 1 . In the specimen of text-fig. 17b, however, the first upward growing theca of each
stipe originates left-handedly, indicating an opposite sense of torsion.

As a consequence of the tendency for proximal thecae to overlap earlier thecae and curve towards the
rhabdosome midline half-way down the manubrium, growth stages take on a characteristic dumb-bell shape
(text-fig. 17d, g; Cooperand McLaurin 1974, text-fig. 1/).

External morphology of prothecal folds. The prothecal folds described above differ from the ‘normal’ prothecal
folds seen in sinograptids in that they produce only a slight protrusion or node in the dorsal rhabdosome
margin. Instead of growing up and around in an inverted U-shape, the protheca curves around towards the
rhabdosome’s midline before doubling sharply back on itself to leave a deep invagination in its dorsal margin.
At the same time it expands laterally, with later fuselli lapping on to earlier fuselli to form a flange analogous
with the involute spire of nautiloids (text-fig. 19a). The structure shows well in the prothecae of th4 1 and th32
in text-fig. 17a and of th3 1 in text-fig. 17i. An alternative interpretation of this structure is possible and is
shown in text-fig. 19b.

It is worth noting that the plate-like structure formed by the invagination in the dorsal prothecal wall is
clearly visible in our specimens because they are internal moulds. This structure may not be very apparent
where the periderm is preserved and morphology can be inferred only from the external surface.

Discussion. The flattened Nelson and Victorian specimens bear the distinctive massive manubrium
and long sicula of the Ningkuo Formation specimens and share similar growth stages. No Chinese
specimens have developed stipes but, from the incipient stipes present, stipe divergence angle was
probably somewhat greater (325-330°) than in the Australasian specimens (267-300°). However,
apart from this possible difference, specimens from the three regions match well and are here
included in the same sub-species. The Nelson specimens represent the informal Pseudisograptus
manubriatus Form C of Cooper and McLaurin (1974) and Cooper (1979).

The unflattened material from the Ningkuo Formation ( P . bellulus and P. m. janus), together with

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PALAEONTOLOGY, VOLUME 29

the Texan specimen of P. m. texanus described by Bulman, provides the only detailed morphologic
information on the proximal structure of manubriate species, and in particular, the structure of the
manubrium. It is perhaps surprising that such an elaborate structure should show variation in such
a fundamental feature as the number of thecae involved in its formation. The variation is, however,
in keeping with the variation in size and proportions of the manubrium in flattened material of this
and all other manubriate species.

B

C

text-fig. 19. Pseudisograptus manubriatus janus ssp. nov. a and B, prothecal morphology based on
th4 1 in specimen X33. a, the developing protheca envelops the preceding theca (th3 1 , outlined by
dashed line) and expands laterally near its origin such that later fuselli lap on to earlier fuselli to
produce a flange; b, alternative interpretation in which the ‘flange’ represents a sharp re-entrant loop
in the growth path of the developing protheca— this interpretation requires that there is minimal
envelopment of the preceding theca and is, in our view, less likely, c, transverse section of rhabdosome
at the level of th5\ based on specimen of text-fig. 17f.

The number of thecae involved in the manubrium, and hence the point of flexure in the dorsal
stipe margin that defines the manubrium base, is determined by the growth paths of the first few
pairs of thecae. Those specimens in which the sicula and proximal thecae continue their downward
growth to a greater than average length before deflecting outwards allow room for a greater than
average number of thecae to assume initially downward growth and thus produce a longer and
larger manubrium. An interesting implication of this control, or influence, on subsequent thecal
growth pattern by earlier-formed thecae is that a feed-back mechanism probably exists to guide
later thecal zooids in the growth direction of their thecae and, particularly, when to make the sharp
flexure and assume upward growth. Feed-back is presumably provided by the thecal zooid ’feeling’
ahead, and can be regarded as a special case of the feed-back mechanism that guides the growth
paths of thecae at the distal end of the stipe. The sicula and initial thecae of P. m. janus, and indeed
of all manubriate species, play an important role in influencing the size, shape, and subsequent
development of the rhabdosome.

In New Zealand P. m. janus is most readily confused with P. m. koi which is found in the same
beds. It is most easily distinguished by the size and characteristic wedge-shape of its manubrium.
Manubrium size (length x width) is larger than the largest manubria in P. m. koi. There is relatively
little variation in stipe divergence angle (unlike P. m. koi, which ranges widely) and the stipes are
always straight (not commonly curved as in koi). Sicula length is generally greater than that of P.
m. koi, and manubrium length + infradorsal length (a measure of the ‘depth’ of the proximal region)
is also greater (text-fig. 14a, c, e, g).

On the PCA plot, janus plots as a group distinct from koi (text-fig. 6) but with a relatively wide
scatter. One specimen (shown at the top of the group) is morphologically transitional towards the
koi group, raising the question of whether or not it should be placed with the latter. On the
reclassification test, however, no change was made to the original assignment, so it is here included
with janus.

COOPER AND NI: P S EU D I SOG R A PTU S

347

First component ( 50%)

text-fig. 20. PCA plot of the specimens with long siculae (Group 2; Pseudisograptus manubriatus
harrisi ssp. nov. and P. m. janus ssp. nov.) from Willey’s Quarry, Victoria, together with the six
specimens of P. m. janus from Jimmy Creek, north-west Nelson, New Zealand, showing slight overlap

in their fields of morphology.

From P. hastatus, P. m. janus is distinguished by its much larger manubrium, longer sicula, and
strong outward deflection of proximal thecae. From P. m. manubriatus the subspecies is readily
distinguished by its longer sicula and manubrium size and proportions.

Pseudisograptus manubriatus texanus ssp. nov.

1968 Isograptus manubriatus (T . S. Hall); Bulman, pp. 212-214, figs. 1 and 2.

Diagnosis. Pseudisograptus with the size and outline of P. m. manubriatus but with the second thecal
series overlapping the first in the proximal region, causing the line of junction between the two on
the reverse side to be strongly displaced towards the stipe1 side, as seen in reverse view.

Holotype. SM A60314, in the Sedgwick Museum, Cambridge, from the Port Pena Formation, Marathon,
Texas, is here nominated as holotype.

Horizon. Berry (1960) gives the range of P. manubriatus in the Marathon section as Zones 8, Isograptus , and
9, Paraglossograptus tentaculatus.

Name. From Texas, the region from which the type, and only specimen, comes.

Discussion. From Bulman’s illustration, the Texas form is indistinguishable from P. m. manubriatus
in size and rhabdosome outline shape. The only significant point of difference lies in the incipient
pseudopericalycal structure and symmetry of the manubrium; the second thecal series overlaps the
first in the proximal region such that the line of junction between the two on the reverse side (i.e.
between th22 and th3 1 ) is strongly displaced towards the stipe1 side. Thus the origins of th4 1 and
th5 1 which form part of the manubrium are obscured from view on the reverse side, and the reverse
face of the manubrium is composed entirely of thecae of stipe2, apart from th3 1 .

Although at first glance the proximal structure looks very different from that of other manubriate
species, such as P. m. janus and P. m. manubriatus , it can be simply derived from them by displacing

348

PALAEONTOLOGY, VOLUME 29

the growth paths of proximal thecae about the rhabdosome midline axis in an anticlockwise
rotational sense. Such a rotation would result in the early thecae of the first thecal series overlapping
subsequent thecae at the base of the manubrium, as shown by Bulman’s Fig. 2c. The structure
could be brought about by a relatively minor alteration in the development programme of the
rhabdosome. The final result, however, is distinctive and appears to be unique among pseudiso-
graptid species. It may eventually warrant separation of the Texan material as a distinct species.

So far as is known the subspecies is confined to the Texan material, but its presence in Victoria
is hinted at by a specimen from Chinaman’s Creek in Victoria (Cooper and McLaurin 1974,
text-fig. 1 d) in which the thecal series may be superposed.

Pseudisograptus bellulus sp. nov.

Plate 26, fig. 8; text-fig. 21

Diagnosis. Pseudisograptus with the general size and shape of P. hastatus , but with a ventrally
expanding manubrium, reaching about 2-2 mm wide at the base; simple prothecal folds present.

Holotype. NIGP 84735, from the Ningkuo Formation, Fentoushan, near Jiangshan, Zhejiang Province, China;
the only available specimen, preserved in full relief in pyrite as an internal mould in reverse aspect.

Horizon. Bed 1 1 in the Fengzou section, Fentoushan, measured by Han Nairen et al. (1984). It is associated
with P. m. janus , Didymograptus hirundo , Cardiograptus amplus , and Pseudotrigonograptus ensiformis , and
represents the C. amplus Zone, equivalent to upper Yapeenian.

Name. Bellulus , elegant.

Description. The rhabdosome has the general size and shape of the earlier P. hastatus. The sicula is at least
5-2 mm long with a free proximal portion of at least 1-2 mm. The manubrium is 1-6 mm long, has concave
shoulders, and expands towards its base, reaching 2-2 mm wide. The shoulders have an undulating profile
resulting from prothecal folding.

Only the proximal portions of the stipes are preserved, and they measure 1.9 mm in width. Stipe divergence
angle is 300°.

Development is of dextral mode and isograptid type. The exact point of origin of th 1 1 on the sicula cannot
be seen but is at or near the top of the preserved portion of the sicula in our single specimen (text-fig. 21).
Till2 arises on the reverse side of th 1 1 , at least 1-2 mm down and, as in P. m. janus, grows up and across to
the stipe2 side of the rhabdosome before commencing its downward growth. Th2' arises in similar fashion to
that in P. m. janus, growing down for 2-2 mm and completely overlapping thl 1 before turning sharply outwards.
Th3‘ and th4 1 have weak prothecal folds; th4‘ makes a sharp flexure to commence upward growth of the stipes.
On the stipe2 side, th22 grows down symmetrically opposite to th3 1 and partially overlaps the preceding thl2.

41

text-fig. 21. Pseudisograptus bellulus sp. nov., holo-
type, NIGP 84735 from the Ningkuo Formation,
Fentoushan, near Jiangshan, China, in full relief
(internal mould), x 15.

COOPER AND NI: PSEUDISOG RA PTUS

349

Th22, th32, and th42 all appear to have weakly developed prothecal folds; th42, like its counterpart th4 1 ,
makes the sharp upward flexure to commence upward stipe growth.

Compared with P. m. janus and P. m. texanus , relatively few thecae of the two thecal series overlap each
other, and only the sicula, thl1, and th 1 2 show the plaited arrangement characteristic of Pseudisograptus. As
in P. m. janus and P. m. manubriatus , but unlike P. m. texanus , the two thecal series do not overlap each other
in the proximal region, their line of junction being represented by the contact between thl2 and th2 1 ,
approximately in the bilateral plane of the rhabdosome.

Discussion. Although only a single specimen is available, it is preserved in full relief with good
growth lines, and proximal development and structure are clearly portrayed. The species in outline
form most closely resembles P. hastatus from the early part of the upper Castlemainian, Ca3. It
differs in the expanding manubrium which reaches a width considerably greater than that reached
by P. hastatus. In the attitude of its proximal thecae, however, it more closely matches the smaller
P. gracilis from the upper Ca3, inferred to be its nearest relative. Nothing is known of its range of
morphologic variation. Because the probability of P. bel/ulus belonging to either P. gracilis or P.
hastatus is in both cases less than 0 001 (using the /-test on manubrium width), it is here regarded
as a distinct species.

Pseudisograptus gracilis (Ruedemann, 1947)

Text-fig. 22a-e

1947 Isograptus caduceus var. gracilis Ruedemann, p. 351, pi. 57, figs. 15 and 16.

1973 Isograptus hastatus Harris, Form B, Cooper, pp. 82-84, text-fig. 20 a-e (non text-fig. 20/-/).

1979 Pseudisograptus hastatus (Harris), Form B, Cooper, p. 78, pi. 14, figs, r, k\ text-fig. 59a, b.

Measured material. Eighteen specimens: VG 94, 95, 152, 156, 158; PR 282, 289, 300, 307, 310. 424, 583-588,
and several incomplete specimens, from loc. S2/f552 of Cooper (1979, p. 99), Aorangi Mine track, north-west
Nelson, New Zealand.

Horizon. Castlemainian I. v. maximodivergens Zone in New Zealand, equivalent to the upper part of Ca3 in
Victoria.

Description. The rhabdosome is of smaller overall size than that of P. hastatus and has straighter stipes. Sicula
length averages 3-7 mm (range 3-4-4-3 mm) and is 0-6 mm wide at the aperture. The manubrium averages
1-3 mm (range 0-71-8 mm) in width. Although in several specimens a distinct break in slope below the sicula
apex can be seen, the top of the manubrium cannot be determined in many specimens in which the outline of
the free proximal portion of the sicula and first theca passes smoothly into the manubrium. Supradorsal sicula
length averages 21 mm, i.e. just over half the length of the sicula. The manubrium comprises the proximal
portions of at least the first three pairs of thecae beyond thl 1 , but details of its structure are unknown. From
traces of the interthecal septa (see Cooper 1973, text-fig. 20 d) it is likely that the two thecal series are
symmetrically arranged about the bilateral plane rather than being superposed on each other as in P. m.
texanus. The apertural portions of proximal thecae are directed away from the rhabdosome midline more
strongly than in P. hastatus.

Stipes are short, up to 6 mm long, and bear no more than nine or ten thecae after their point of proximal
flexure. They average 1-2 mm (range 10-1-3 mm) in width proximally and are generally parallel sided. Thecae
are spaced about 3-3 in 3 mm and, like P. hastatus , lack a ventral apertural process.

Discussion. The species is erected for those forms referred to as I. hastatus Form B by Cooper
(1973, 1979). Ruedemann’s I. caduceus var. gracilis from the Glenogle shale of British Columbia
closely matches the New Zealand material, although unfortunately the precise stratigraphic
horizon was not given. Ruedemann’s name, gracilis, thus appears to be the oldest available name
for the species.

The species most closely resembles P. hastatus with which it was formerly included. Both possess
a prominent wedge-shaped ‘manubrium’ and overlap in the range of several of their measured
characters, particularly in dimensions of the ‘manubrium’ (text-fig. 23a) and stipe divergence angle.
From the larger samples of the two forms now available, P. gracilis is most readily distinguished
from P. hastatus by its narrower stipes (text-fig. 23b) and outwardly directed apertures of proximal

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PALAEONTOLOGY, VOLUME 29

text-fig. 22. Pseudisograptus gracilis (Ruedemann) and P. hastatus (T. S. Hall), a-e, P. gracilis, from the
upper Castlemainian Ca3 Zone, Aorangi Mine Track, north-west Nelson, New Zealand: A, VG 152; b, growth
stage, PR 424; c, PR 584; d, immature specimen, PR 307; e, mature rhabdosome, VG 94. f-m, P. hastatus,
from the lower Castlemainian Ca3 Zone, Anthill Creek, north-west Nelson, New Zealand (locality details in
Cooper 1973): f, growth stage, PR 605; G, immature rhabdosome, PR 608; h, PR 120; I, PR 615; j, PR 124; k,
PR 613; l, PR 1 18; m, specimen with traces of interthecal septa, PR 122. a-e, x 5; f-m, x 3.

1 P gracilis (n = 18)

1 P gracilis (n - 17)
2. P hastatus (n - 21)

text-fig. 23. Frequency histogram for Pseudiso-
graptus gracilis (Ruedemann) and P hastatus (T. S.
Hall) of A, manubrium size; b, proximal stipe width;
and c, sicular length. Numbers of specimens meas-
ured are given in parentheses.

COOPER AND NI: PSEUDISOG RA PTUS

351

thecae. When sicula length is plotted against stipe width (text-fig. 24), two clear groups result; on
the PCA plot the two species form clearly distinguishable groups with non-overlapping fields
(text-fig. 25), agreeing with the reclassification test which made no change to the original specific
assignment. There seems little doubt that P. gracilis was derived from the earlier P. hastatus.

text-fig. 24. Sicular length plotted against stipe
width for thirty-nine specimens of Pseudisograptus
gracilis (Ruedemann) and P. hastatus (T. S. Hall).

Pseudisograptus hastatus (Harris, 1933)

Text-fig. 22f-m

1914 Didymograptus caduceus manubriatus T. S. Hall (pars), pi. 17, fig. 13.

1933 Isograptus hastatus Harris (pars), p. 104, text-figs. ?33, 34-36.

1973 Isograptus hastatus Harris, Form A, Cooper, pp. 82-84, text-fig. 20/-/ (non text-fig. 20 a-e =
Pseudisograptus gracilis).

1979 Pseudisograptus hastatus (Harris), Form A, Cooper; Cooper, p. 78, text-fig. 59c, d.

Holotype. GSV 63654, Museum of Victoria, figured by Harris (1933, text-fig. 36) and refigured by Cooper
(1973, text-fig. 20A:). Type locality is 'Sandy Creek Road near Bagshot, Bendigo’.

Measured material. Twenty-two specimens: PR 114, 116, 1 18-122, 124-127, 166, from loc. S2/f565 of Cooper
(1979, p. 100); PR 602, 609, 613, 616, from loc. M25/f49; PR 603, 608, 611, 615, from loc. M25/f50;
PR 605-607, from loc. M25/f51; all in Anthill Creek, Aorangi Mine area, north-west Nelson, New Zealand.

Horizon. Uppermost part of Castlemainian lunatus Zone in New Zealand, equivalent to the lower part of Ca3
in Victoria.

Description. The rhabdosome is comparable in size and, except for its manubrium, in shape to small members
of the co-occurring Isograptus victoriae maximus population. The sicula averages 4-9 mm (range 4-4-5-7 mm)
in length. There is no clearly defined free proximal portion of the sicula, as in later pseudisograptids; the apex
passes smoothly into the shoulders of the manubrium. The height of the manubrium cannot therefore be
determined, but its width is rather variable, averaging 1-4 mm (range 11-1-8 mm; V = 14). Supradorsal length
of the sicula averages 2-7 mm (range 2-2-3-2 mm), i.e. about half the overall length of the sicula. The

352

PALAEONTOLOGY, VOLUME 29

manubrium comprises the proximal portions of at least the first two pairs of thecae beyond thl *, but details
of its structure are unknown. Proximal thecae are relatively straight, and their apertural portions are directed
away from the rhabdosome midline less strongly than in all subsequent pseudisograptid species.

Stipes reach 9 mm in length, average 1-9 mm (range 1 -6-2-2 mm) in proximal width, and diverge at about
310° (range 285-330°). They taper gradually throughout their length and are curved proximally before
becoming straight distally, giving the rhabdosome a rounded rather than V-shaped proximal outline. Thecae
are spaced about 5-5 in 5 mm; their apertures are inclined at a high angle, giving deep 'thecal excavations’,
and are simple, not extended into a ventral process as in P. manubriatus.

First component (56%)

text-fig. 25. PCA plot of specimens of Pseudisograptus gracilis (Ruedemann) and P. hastatus (T. S.
Hall) from Aorangi Mine, north-west Nelson, New Zealand (locality details in Cooper 1973).

Discussion. Specimens grouped informally by Cooper (1973, 1979) as I. hastatus Form A are here
given full specific status. They include forms which closely match Harris’s holotype (see Cooper
1973) and are particularly interesting as they apparently represent the earliest known manubriate
species, and are presumed to be ancestral to the manubriate stock. Although a larger sample
population is available for study, little is known of the early development of the rhabdosome or of
its proximal structure. However, the manubrium, judging from its size, is well developed.

Of the four specimens figured by Harris, three (his text-figs. 34-36) are from the upper Castle-
mainian, Ca3, and match the New Zealand specimens from the equivalent beds (upper part of I. v.
lunatus Zone). One specimen (his text-fig. 33) is from the Yapeenian (loc. Ba71) and represents a
growth stage. Because the age would be anomalous and the figure (at x 1) does not allow critical
assessment, inclusion of the specimen in the species is here queried. So far as is known, P. hastatus
is confined to the lower part of Ca3.

The distinction from P. gracilis is discussed under that species. From P. manubriatus s.l. it is
distinguished by the lack of a break in slope at the top of the manubrium, its relatively straight
proximal thecae, the lack of a thecal ventral apertural process, and a generally more isograptid
appearance.

COOPER AND NI: PSEUDISOGRAPTUS

353

Pseudisograptus dumosus (Harris, 1933)

Plate 25, figs. 2 and 7; text-fig. 26a-k

1933 Isograptus dumosus Harris, p. 94, pi. 6, fig. 2 a-c; text-figs. 37-39.

1933 Isograptus caduceus velata Harris, pp. 93-94, text-fig. 40.

1973 Isograptus dumosus Harris, Forms A and B, Cooper, pp. 78-82, text-fig. 18 e-p (non text-fig.
1 Sa-d = P . jiangxiensis Yu and Fang).

1979 Pseudisograptus dumosus (Harris), Forms A and B, Cooper; Cooper, pp. 77-78, pi. 14, figs, g , /;;
text-fig. 58c-/.

Lectotype. GSV 63651 in the Museum of Victoria, nominated and figured by Cooper (1973, p. 78, text-fig.
18o). Type locality is ‘Ba71, Gisborne Creek’, Victoria.

Measured material. Form A, twenty-two specimens: VG 89, 140; PR 27, 280, 281, 306, 423, 429, 432-434,
587-589, 591-597, and 599, all from loc. S2/f552 of Cooper (1979, p. 99), Aorangi Mine Track, north-west

text-fig. 26. a-k, Pseudisograptus dumosus (Harris), a-f. Form A, from the Castlemainian Ca3 Zone, Aorangi
Mine Track, north-west Nelson, New Zealand (locality details in Cooper 1973): a and b, immature rhabdo-
somes, PR 598 and PR 590; c, PR 433; d, PR 429; e, PR 594; f, PR 591 g-k. Form B, from the Yapeenian of
Jimmy Creek, north-west Nelson, New Zealand, except for i which is from Willey’s Quarry, Victoria: g, PR
412; h, PR 413; t, P 103885; J, PR 28; k. PR 414. l-r, Pseudisograptus jiangxiensis (Yu and Fang), from the
Yapeenian of Jimmy Creek, north-west Nelson, New Zealand: m, PR 559a; n, advanced growth stage, PR
564; o, PR 366; p, PR 369; q, PR 600; r, PR 384. All x 5.

354

PALAEONTOLOGY, VOLUME 29

Nelson, New Zealand. Form B, ten specimens: PR 28, 42, 315, 316, 339, 353, 374, 377, 412-415, from loc.
S2/f540 of Cooper (1979, p. 97), Jimmy Creek, north-west Nelson, New Zealand.

Horizon. Castlemainian maximodivergens Zone in New Zealand, equivalent to the upper part of Ca3 in
Victoria; and Oncograptus Zone, Yapeenian.

Description. Two informal forms are recognized: Form A from the maximodivergens Zone (upper Ca3) and
Form B from the Oncograptus Zone (Ya).

The rhabdosome of Form A is small and compact with stipes barely developed beyond the manu-
brium. The sicula averages 3-7 mm (range 3-3-41 mm) in length. The apex of the sicula and first theca
protrude about 1 mm above the manubrium which expands rapidly to a basal width averaging 1 -7 mm (range
I -4-2-1 mm). The manubrium averages only 1-4 mm (range 1-01-6 mm) in length and is thus relatively broad
and squat. The stipes are generally comprised of fewer than four thecae each and average 1-1 mm (range 0-8-
1-5 mm) in width; they diverge at about 314° (range 270-340°). The ventral margin of the rhabdosome is
rounded. Width of the rhabdosome at the level of the base of the manubrium is 4- 1 mm (range 3 0-4-8 mm).

A I P dumosusB (n-tO) YAPEENIAN

3 P. jiangxiensis (r> = 12) B 2 P dumosus B (n = 10)

text-fig. 27. Frequency histograms for Pseudisograptus dumosus (Flarris) Forms A and B, Cooper and P.
jiangxiensis (Yu and Fang) of a, sicular length and B, manubrium width. Number of specimens measured are

given in parentheses.

Form B has slightly larger overall rhabdosome dimensions with longer stipes bearing up to six thecae each.
The sicula averages 4-0 mm (range 3-3-4-8 mm) in length; the manubrium averages 2 1 mm (range 1 -7-2-4
mm) in width and 1-4 mm (range 11-1-6 mm) in length and has similar squat proportions to that of Form A.
Stipe width is similar but rhabdosome width is appreciably wider, averaging 4-7 mm (range 4 0-5-9 mm).

Traces of interthecal septa can be seen in a few specimens of each form (text-fig. 26a-k) and show that the
two thecal series were symmetrically arranged about the plane of bilateral symmetry as in other Australasian
Pseudisograptus species.

Discussion. Specimens of P. dumosus from the upper Ca3 Zone in New Zealand were informally
designated Form A by Cooper (1973, 1979) and those from the Oncograptus Zone (Yapeenian)
Form B. Although the mean values of most of the measured characters are appreciably different in
the two forms, there is considerable overlap in range of all characters (text-figs. 27 and 28). On the
PCA plot (text-fig. 29) there is also considerable overlap of the fields of the two forms and this is
reflected in the reclassification test: seven of the twenty specimens of Form A were reclassified in
Form B, and one of the eight specimens of Form B was reclassified in Form A. Because of this
relatively high proportion of reassigned specimens it is unwise to recognize the forms as distinct
subspecies. The two forms have biostratigraphic value and are retained here as intraspecific informal

COOPER AND NI: PS E U D I SOG RA PTU S

355

Rhabdosome width (mm)

text-fig. 28. Sicular length plotted against rhabdosome width for forty-one specimens of Pseudiso-
graptus dumosus (Harris) Forms A and B, Cooper and P . jiangxiensis (Yu and Fang), from the
Upper Castlemainian and Yapeenian of Aorangi Mine, north-west Nelson, New Zealand.

groups. The specimens described and figured by Harris (1933), including the lectotype (Cooper
1973, text-fig. 18o), most closely match Form A, but are from the Yapeenian of Victoria and may
represent the smaller end of the Form B range.

Harris erected the variety Isograptus caduceus var. velata with a minimum of description and
only one figure (at natural size). He grouped it with the manubriate species, especially with P.
dumosus (Harris 1933, p. 105). Although few details can be seen in his figure, the form of the
rhabdosome matches well with Form B (text-fig. 26k) and the variety is here synonymized accord-
ingly. The specimens figured by Tsai (1974, pi. 9, figs. 8, 9) as I. manubriatus from the I. gibberulus
(/. victoriae) Zone of Kazakhstan more closely match P. dumosus Form B and are here included in
the species.

Pseudisograptus jiangxiensis (Yu and Fang, 1981)

Plate 25, figs. 1 and 6; text-fig. 26l r

1973 Isograptus dumosus Harris, Form C, Cooper, pp. 78-82, text-fig. 18 a~d ( non text-fig. 18 e-p).

1979 Pseudisograptus dumosus (Harris), Form C, Cooper; Cooper, pp. 77-78, text-fig. 58a, b.

1981 Arienograptus jiangxiensis Yu and Fang, pp. 29-30, pi. 1, figs. I, 2; text-fig. 3.

1981 Arienograptus zhejiangensis Yu and Fang, pp. 30-31, pi. 1, figs. 3, 4; text-fig. 4.

356

PALAEONTOLOGY, VOLUME 29

text-fig. 29. PCA plot of specimens of Pseudisograptus dumosus (Harris) Forms A and B, Cooper,
with widely overlapping fields, and P . jiangxiensis (Yu and Fang) with a discrete field of morphology.

Measured material. Twelve specimens: PR 315, 338, 366, 384, 400, 410, 425, 538, 559, 575, 600, and 601, from
loc. S2/f540 of Cooper (1979, p. 97), Jimmy Creek, north-west Nelson, New Zealand.

Horizon. Yapeenian, lower Oncograptus Zone in New Zealand, equivalent to Yal in Victoria. The species was
described from the Glyptograptus austrodentatus Zone and Cardiograptus ampins Zone of the Ningkuo shale.

Description. The rhabdosome is composed of little more than an enlarged manubrium; its outline is like that
of P. dumosus but is more massive and ‘deeper’, with a greater distance between the base of the manubrium
and ventral rhabdosome margin and relatively shorter stipes. There are twelve thecal apertures in the infrador-
sal ventral margin whereas in P. dumosus (both Form A and Form B) there are only nine or ten. The sicula
and th 1 1 protrude slightly, giving a rather pointed outline to the ventral margin rather than a smoothly
rounded curve as in P. dumosus.

The sicula averages 5-2 mm (range 4-6-6 0 mm) in length and, as in th 1 1 , its ventral margin is extended into
a denticle-like process. Its free proximal portion is 1-2 mm long, generally about 1-3 mm. Ventrally concave
recurvature of the distal portions of proximal thecae is more marked than in P. dumosus , and imitates the
caduceus condition. The manubrium is broader than that of P. dumosus (text-fig. 27b) and expands more
rapidly; it averages 31 mm (range 2-8-3-3 mm) in width and 1-5 mm (range 1-2-17 mm) in length. Manubrium
structure is unknown but traces of interthecal septa in some specimens (text-fig. 26n-p) suggest that, as in P.
dumosus , the two thecal series lie symmetrically to either side of the rhabdosome’s plane of bilateral symmetry.

Stipes are short and possess only two or three thecae each beyond the base of the manubrium. They average
T3 mm (range 11-1-5 mm) in width and diverge at about 322° (range 305-330°).

Discussion. The Nelson material was originally described informally as P. dumosus Form C by
Cooper (1973, 1979). The distinction from P. dumosus has been outlined in the description above.
Apart from the differences in rhabdosome shape, the wider manubrium serves to distinguish P.
jiangxiensis from dumosus. On the PCA plot (text-fig. 29) P. jiangxiensis forms a group distinct

COOPER AND NI: P S EU D I SOG RA PTU S

357

from P. dumosus and the reclassification test made no changes to the original assignment. Although
we have only a comparatively small sample to go by, there seem good grounds for the recognition
of the specimens as a distinct species. The species is confined to the lower Yapeenian, in the same
beds as P. dumosus Form B.

Yu and Fang (1981) erected the genus Arienograptus with A. jiangxiensis as type species. Their
figures show an incompletely developed rhabdosome that, allowing for the different modes of
preservation, matches well with growth stages from Nelson (text-fig. 26l-p). The main point of
difference concerns the growth paths of proximal thecae; the Chinese specimens are all preserved in
reverse view, whereas at least one of the Nelson specimens (text-fig. 26p) shows the obverse view.
We therefore regard the Nelson specimens as belonging to Yu and Fang’s species and their genus
Arienograptus as a junior synonym of Pseudisograptus. Their species A. zhejiangensis is a later growth
stage, closely matching Nelson specimens (e.g. Cooper 1973, text-fig. 18c) and is synonymized
accordingly. Their account of proximal development has th 1 2 budding off th22 before l h 2 1 ; if
correct, this would be unique among the dichograptids. Unfortunately, the feature cannot be verified
from their published illustrations.

NOTES ON OTHER MANUBRIATE SPECIES
Pseudisograptus tau (Harris, 1933)

The species Maeandrograptus tau Harris is clearly morphologically related to P. manubriatus koi , particularly
those variants with wide open rhabdosomes and loss, or partial loss, of isograptid symmetry (text-fig. 12d).
P. tau seems to have gone a stage further and has acquired maeandrograptid symmetry; the rhabdosome’s
midline passes through the sicula in specimens figured by Cooper (1973, text-fig. 24/?, d). The species has
a prominent manubrium and is therefore excluded from Maeandrograptus Moberg and included here in
Pseudisograptus. Harris (1933) gives the horizon as Yapeenian- the species is found together with P. m.
manubriatus at Willey’s Quarry, Ya2.

Pseudisograptus ? aggestus (Harris, 1933)

Harris based this species on two specimens from the upper Castlemamian at Yandoit. The holotype was
refigured by Cooper (1973); although the stipes are undeveloped (or broken off), the distal portions of proximal
thecae have lower inclination than in other manubriate species and are somewhat crowded in the proximal
region. If the New Zealand specimens (text-fig. 30a, b) are correctly assigned to the species, then a more
advanced growth stage is available for study. The stipes are barely reclined, 2-1 mm wide and reach 4 4 mm
long. Thecae are long and narrow, of very low inclination, and of manubriate type. The manubrium is weakly
developed, 0-6 mm long, and 1-5-2 0 mm wide. The free proximal portion of the sicula and first theca
protrude 1-01-3+ mm above the top of the manubrium. Isograptid symmetry is weak or lacking altogether.

/

text-fig. 30. a and b, Pseudisograptus ? aggestus (Harris) from the upper Castlemainian Ca3 (I. v.
maximodivergens Zone) of Aorangi Mine Track, north-west Nelson, New Zealand (locality S2/f522
of Cooper 1973). Two specimens thought to represent the mature rhabdosome of the species other-
wise known only from the immature holotype: A, PR 570; B, PR 569. Both x 5.

358

PALAEONTOLOGY, VOLUME 29

Because it has a manubrium the species is precluded from Maeandrograptus Moberg. It is morphologically
closest to P.l geniculatus (Skevington), the two species sharing a weakly developed manubrium and stipes
that are barely reclined. P.l geniculatus has good isograptid symmetry, however, and its proximal thecae are
more highly inclined. The inclusion of aggestus in Pseudisograptus would presume that the lack of good
isograptid symmetry is a secondary loss feature, as in P. tau. The species can be less certainly linked with
other Pseudisograptus species, however, and its generic reference is less certain. It is confined to the upper
Castlemainian, Ca3.

Pseudisograptusl geniculatus

With its barely reclined stipes and weakly developed manubrium, this species at first sight does not look much
like other manubriate species. Its proximal structure can be interpreted as manubriate (text-fig. 1b) and this
feature, together with the form of its thecae and presence of prothecal folds, is the basis for its tentative
inclusion in Pseudisograptus. The species is known from the D. hirundo Zone of Oland (Skevington 1963,
pp. 67-70).

British pseudisograptids

In his revision of the isograptids of England and Wales, Jenkins (1982) referred a number of species to
Pseudisograptus. His P.l menaiensis and the similar P. angel include the only comparatively well-preserved
material; they differ from the Australasian species in possessing a barely developed manubrium, and thecae
(particularly in the proximal part of the stipes) of relatively high inclination. As recognized by Jenkins, P.l
menaiensis is reminiscent of isograptids of the caduceus group, but it has a much longer sicula and proximal
thecae than in any caduceus group form; this feature, together with the sigmoidal curvature of proximal thecae
and the weakly developed manubrium, suggest that both P.l menaiensis and P. angel are pseudisograptids.
The British species, together with P.l geniculatus , however, appear to form a distinct European group which
may, as Jenkins pointed out, have been independently derived and not belong to Pseudisograptus at all. Until
more is known of these British forms, they are tentatively retained within Pseudisograptus , following Jenkins.

The forms described by Jenkins as P. Stella , P. n. sp. A, and P. n. sp. B are either too poorly preserved or
too fragmentary to allow their morphologic affinity with other species to be assessed.

COMMENTS ON RELATED GENERA

Apiograptus and Exigraptus

On the basis of its generally isograptid symmetry and similarities in development and thecal morphology,
Apiograptus Cooper and McLaurin, 1974 was regarded by its authors as being most closely linked with
Pseudisograptus , particularly with P. m. janus (formerly P. manubriatus Form C). The biserial, incipiently
monopleural rhabdosome can be derived from that of P. m. janus or a similar form by a continuation of the
tendency of the dorsal stipe margin to grow around in a loop and recross the path of its earlier growth (Cooper
and McLaurin 1974, pp. 82 83). Proximally, in material from Chinaman's Creek, Victoria, the stipes enclose
the manubrium in pseudopericalycal fashion but distally they are apparently dipleural; two specimens of
uncertain affinity described by Beavis (1962) from Bendigo, and which may represent the genus, have a
monopleural distal stipe arrangement.

With its glossograptid thecal form, Harris and Thomas (1935) were led to include the type species, A.
crudus , in Glossograptus albeit tentatively. Cooper and McLaurin pointed out (p. 75) that Glossograptus could
only be derived from Apiograptus if there were a change from isograptid to dichograptid ( = artus) development
type and platycalycal to pericalycal mode. It is particularly interesting therefore that G. ciliatus from the
Athens Shale described by Finney (1978, fig. 4) has dextral isograptid development differing from that generally
accepted for Glossograptidae (Bulman 1970, fig. 62); further, its proximal structure is just what would be
expected if the ' Apiograptus trend' was continued a stage further; the base of the manubrium is defined by
th5 1 instead of a later theca, and the second thecal series develops on the reverse side of the rhabdosome. The
loop is right-handed, rather than left-handed as it appears to be in Apiograptus ; in P. m. janus , however, the
loop is either right- or left-handed and sense of rotation may not be significant.

On the other hand, the features linking Apiograptus with P. manubriatus (isograptid symmetry, similarity in
development and in thecal morphology) are now known to be plesiomorphic (primitive) for the group which
includes Kalpinograptus and the glossograptids and therefore are not useful for subdivision of the group.
Although its proximal structure remains to be confirmed by the discovery of unfiattened specimens, we feel

COOPER AND NI: PSEU DISOG RAPTUS

359

Apiograptus is best regarded as a sister group to the Glossograptina sensu Jaanusson (text-fig. 4), being
distinguished from them by its less ‘advanced’ pseudopericalycal structure.

The genus Exigraptus Mu in Mu et al., 1979, with E. clavus as type species, is closely similar to Apiograptus.
The three differences cited by Mu et al. (1979, p. 164) are likely to be significant at the species level rather
than genus level:

1. Exigraptus is dipleural. Monopleural stipe arrangement in Apiograptus applies only to the proximal
region, as determined from the specimen figured by Cooper and McLaurin (1974, text-fig. 2c); distally the
stipes appear to be in dipleural arrangement. It seems likely to us that there will be some variation in this
character among species of the genus and that it will not be a reliable basis for generic distinction.

2. Maeandrograptid symmetry. The specimens of A. crudus figured by Cooper and McLaurin have proximal
symmetry ranging from isograptid to maeandrograptid and in this feature resemble P. manubriatus koi.
Proximal symmetry is thus not a diagnostic character.

3. Thecal llexure. Proximal thecae in Exigraptus are more sharply flexed than in A. crudus and there are
fewer downwardly directed thecae; this seems to be the most significant point of difference. However, among
the specimens from Chinaman’s Creek figured by Cooper and McLaurin there is considerable variation in the
number of downwardly directed thecae suggesting, again, that the Chinese material differs at the level of
species rather than genus. There may well be a similar range of variation among Chinese material, as suggested
by the slab figured by Chen (1982, pi. 1) which contains an array of forms ranging from those with wide
rhabdosomes, rounded proximal ends, and many downwardly directed thecae, listed as Exigraptus globosus
sp. nov. (surely conspecific with A. crudus), to those with narrower rhabdosomes and squarer proximal ends,
listed as E. clavus Mu, E. uniformis Mu, E. confertus sp. nov., and E. latus sp. nov. (A population study is
clearly needed to verify the presence of the five species as opposed to a single, variable population.)

For these reasons we think Exigraptus is best regarded as a synonym of Apiograptus.

Kalpinograptus and Apoglossograptus

Kalpinograptus Jiao, 1977, with K. spiroptenus as type species, is a manubriate form with a rhabdosome
generally shaped like that of P. manubriatus s.l. It comes from the Saergan Formation of Kalpin, Xinjiang,
where it is associated with Nemagraptus exilis and Pseudoclimacograptus scharenbergi minor and represents an
interval considerably younger than that of the species discussed here. The structure of the first few thecae
appears to be generally similar to that of P. manubriatus, but it is not clear from Jiao’s diagrams or illustrations
whether the sicula and first three thecae are platycalycal (as in manubriatus) or whether th 1 2 wraps around
the ‘obverse’ side of the sicula in a pericalycal fashion; from Jiao’s figs. 5 a and 5b it would appear that they
are platycalycal. In any case, subsequent development differs from that of manubriatus in that the two thecal
series develop on either side of the sicula, enveloping it and producing a pseudopericalycal structure as in
Glossograptus ciliatus and Cryptograptus marcidus (Finney 1978).

The first thecal series expands across the sicula, th 1 1 , and th 1 2 on the reverse side of the rhabdosome to
form the manubrium; on the obverse side the manubrium is formed by the second thecal series. In P. m.
texanus, the only pseudisograptid with comparable manubrial asymmetry, it is the other way round; the
second thecal series expands across the sicula on the reverse side. Kalpinograptus thus shares affinities with
the manubriate isograptids and the glossograptids.

From the Athens Shale of Alabama, Finney (1978) has described closely similar forms (but including more
mature rhabdosomes) as Isograptus lyra Ruedemann, referring them to his new genus Apoglossograptus (a
nomen nudum). Growth stages figured by Finney (1978, fig. 8 a-d) show that the structure is pseudopericalycal;
th 1 2 grows around to that side of the sicula opposite thl ', and does not overlap it on the reverse side as in
pseudisograptids. The distinctive arrangement of stipes and the large proximal boss produced by overlapping
thecae in the manubrium, as well as thecal morphology and rhabdosome shape, are features shared with K.
spiroptenus and it seems most probable to us, on the basis of the published evidence by Jiao ( 1977) and Finney
(1978), that the two are congeneric.

Origin of the glossograptids

Finney (1978) has shown that in at least two species of glossograptids (G. ciliatus and Cryptograptus marcidus)
development is of isograptid type, thus demonstrating that development type in glossograptids is not ex-
clusively of artus (= ‘dichograptid’) type (Bulman 1970). A case was also made for the reinterpretation of
development type and mode in G. holmi and C. tricornis. Discussion of this problem is beyond the scope of this
paper but we feel that Finney has established that artus development type is not likely to be a synapomorphy for
the group, and that derivation from an ancestor with isograptid development type (the primitive state) is

360 PALAEONTOLOGY, VOLUME 29

more likely. The derivation of artus type from isograptid type in other lineages has already been suggested
(Cooper and Fortey 1983).

The two objections to the hypothesis of Harris and Thomas (1935) that the glossograptids were derived
from the manubriate stock raised by Cooper and McLaurin (1974, p. 75), namely artus development and
pericalycal structure, no longer apply, and the hypothesis is accepted here, at least as a working model. The
glossograptids have, during their early development, an initially downward growth of proximal thecae (up to
the third thecal pair in G. ciliatus) which can be regarded as homologous with that in pseudisograptids,
supporting the hypothesis. Species such as C. tricornis (Bulman 1944; Finney 1978), where this initially
downward growth is confined to the first two thecal pairs, would be interpreted as having partially lost the
feature.

Acknowledgements. We thank Ian Raine and George Scott for helpful discussion and advice with the computer
work, and Richard Fortey for valuable comments on the manuscript. Our colleague, Han Nairen generously
allowed us access to Chinese specimens of P. m.janus. Peter Jell forwarded collections and type material held
by the Museum of Victoria. John Simes took the SEM photographs. The participation of Ni in this project
was made possible by the financial assistance received from the Department of Scientific and Industrial
Research, Wellington, New Zealand.

REFERENCES

beavis, f. c. 1962. Glossograptus crudus from the Bendigo East, Victoria. Aust. J. Sci. 24, 485-486.

1972. The manubriate isograptids. Geol. Mag. 109, 193-204.

— and beavis, s. 1974. The Victorian isograptids and isograptid-like graptoloids. Proc. R. Soc. Viet. 86,
175-213.

berry, w. b. n. 1960. Graptolite faunas of the Marathon Region, West Texas. Pubis Bur. econ. Geol. Univ.
Tex. 6005, 129 pp., 20 pis.

bulman, o. m. b. 1945- 1947. A monograph of the Caradoc (Balclatchie) graptolites from limestones in Laggan
Burn, Ayrshire. Palaeontogr. Soc. (Monogr.), 70 pp., 10 pis. (1945, 1-42, pis. 1-3; 1946, 43-58, pis. 4-6;
1947, 59-78, pis. 7-10).

— 1963. The evolution and classification of the Graptoloidea. Q. J! geol. Soc. Lond. 119, 401-418.

— 1968. The mode of development of Isograptus manubriatus (T. S. Hall). Geol. Mag. 105, 21 1-316.

— 1970. Graptolithina. In Moore, R. C. (ed.). Treatise on Invertebrate Paleontology , Part V (2nd edn.),
xxxii + 163 pp. Geological Society of America and University of Kansas Press, New York and Lawrence,
Kansas.

carter, c. and tailleur, i. l. 1984. Ordovician graptolites from the Baird Mountains, Western Brooks Range,
Alaska. J. Paleont. 58, 40-57.

chen, x. 1982. Early Ordovician Exigraptus and Glyptograptus from Xingan, N. Guangxi and the origin of
the biserial Axonophorous graptolites. Acta palaeont. sin. 21, 505-514.
cooper, r. a. 1973. Taxonomy and evolution of Isograptus Moberg in Australasia. Palaeontology , 16, 45-1 15.
1979. Ordovician geology and graptolite faunas of the Aorangi Mine area, north-west Nelson, New
Zealand. Palaeont. Bull. Wellington , 47, 127 pp., 19 pis.

and fortey, r. a. 1982. The Ordovician graptolites of Spitsbergen. Bull. Br. Mus. nat. Hist. (Geol.), 36,
1 57-302.

— 1983. Development of the graptoloid rhabdosome. Alcheringa, 7, 201-221.

— and lindholm, K. 1984. The phylogenetic relationships of the graptolites Tetragraptus phyllograptoides
and Pseudophyllograptus cor. Geol. For. Stockh. Fork. 106, 279-291.

and mclaurin, a. n. 1974. Apiograptus gen. nov. and the origin of the biserial graptoloid rhabdosome.
Spec. Pap. Palaeont. 13, 75-86.

finney, s. c. 1978. The affinities of Isograptus, Glossograptus, Cryptograptus, Corynoides and allied graptolites.
Acta palaeont. pol. 23, 481-495.

and chen, x. 1984. Bergstroemograptus n. gen. crawfordi (Harris) from the Ordovician of western
Newfoundland. Can. J. Earth Sci. 21, 1 194-1 199.

hall, T. s. 1914. Victorian graptolites. Part IV; some new or little known species. Proc. R. Soc. Viet. 27,
104-118.

han nairen, Li luozhao and jin yushu 1984. New observations on the Ningkuo Formation, Lower Ordovi-
cian, from Jiangshan, Zhejiang. Jl. Gudin College Geol. 4, 1 -8.

Harris, w. j. 1933. Isograptus caduceus and its allies in Victoria. Proc. R. Soc. Viet. 46, 79- 1 14.

COOPER AND NI: P S EU D I SOG R A PTU S

361

and thomas, n>. e. 1935. Victorian graptolites (New Series) Part III. Ibid. 47, 288-313.
jaanusson, v. 1960. Graptoloids from the Ontikan and Viruan (Ordovician) Limestones of Estonia and
Sweden. Bull. geol. Instn Univ. Upsala , 38, 289-366.

jenkins, c. J. 1982. Isograptus gibberulus (Nicholson) and the isograptids of the Arenig series (Ordovician) of
England and Wales. Proc. Yorks, geol. Soc. 44, 219-248.
jiao, Q. 1977. Kalpinograptus, a new-graptolite from the Saergan Formation in Kalpin of Xinjiang. Acta
palaeont. sin. 16, 287 292.

lapworth, c. 1873. On an improved classification of the Rhabdophora. Geol. Mag. 10, 500-504, 555-560.
mu, a. t., ge, m. y., chen, x., Ni, y. n. and yin, y. k. 1979. Lower Ordovician graptolites of southwest China.
Palaeont. sin. 15, 92-98.

ross, R. J. jun. and berry, w. b. n. 1963. Ordovician graptolites of the Basin Ranges in California, Nevada,
Utah and Idaho. Bull. U.S. geol. Surv. 1134, 177 pp., 13 pis.
ruedemann, r. 1947. Graptolites of North America. Mem. geol. Soc. Am. 19, 652 pp., 92 pis.
salter, j. w. 1863. Note on Skiddaw Slate fossils. Q. Jl geol. Soc. Lond. 19, 79-84.

skevington, d. 1963. A correlation of Ordovician graptolite bearing sequences. Geol. For. Stockh. Fork. 85,
298-319.

1968. The affinities of Oncograptus , Cardiograptus , and allied graptolites from the Lower Ordovician.
Lethaia , 1, 31 1-324.

thomas, D. E. 1960. The zonal distribution of Australian graptolites. J. Proc. R. Soc. N.S.W. 94, I 58.
tsai, D. T. 1974. Graptolity Rannego Ordovika Kazakhstana. Izdatel'stvo Nauka, Moscow.

Whittington, H. b. and Rickards, R. b. 1969. Development of Glossograptus and Skiagraptus, Ordovician
graptoloids from Newfoundland. J. Paleont. 43, 800-817.
wiley, E. o. 1981. Phylogenetics: the theory and practice of phylogenetic systematics. John Wiley, New Y ork.
yu, j.-h. and fang, y.-t. 1981. Arienograptus , a new graptolite genus from the Ningkuo Formation (Lower
Ordovician) of South China. Acta palaeont. sin. 20, 27-32.

1983. In Regional Palaeontology of Zhejiang Province , 406 407.

ROGER A. COOPER
New Zealand Geological Survey
PO Box 30 368, Lower Hutt
New Zealand

NI YUNAN

Institute of Geology and Palaeontology
Academia Sinica
Nanjing

Peoples Republic of China

Typescript received 20 March 1985
Revised typescript received 23 September 1985

362

PALAEONTOLOGY, VOLUME 29

APPENDIX

The number of measured specimens (N), minimum value (Min), maximum value (Max), mean value (Mean),
standard error of the mean (x), standard deviation (s), 95 % confidence limits (95 % c.l), and coefficient of
variation (V) are given below for each measured character of each species, together with the correlation matrix
(coefficients significant at the 95 % level are underlined). The minitab program was used to generate these

Statistics. Pseudisoqraptus hastatus

Measured character

N

Min.

Max.

Mean

3X

s

95S C.l.

V

Correlation matrix
1 2 3

4

i

Sicular length

21

4.4

5.7

4.9

.09

.41

4. 8-5. 1

8

2

Manubrium width

21

i.i

1. 8

1.4

.04

.19

1.4-1. 5

14

.420

3

Supradorsal length

22

2.2

3.2

2.7

.07

.33

2. 6-2. 9

12

.675

.447

4

Stipe divergence

18

285

330

312

3

15

305-319

4

.025

.239

-.267

5

Proximal stipe width

22

1.6

2.2

1.9

.04

.17

1. 9-2.0

8

.468

.498

-.046.

.456

Pseudisoqraptus qracilis

N

Min.

Max.

Mean

3X

s

95S C. 1.

V

1

2

3

4

1

Sicular length

17

3.6

4.3

3.7

.056

.22

3.6-3. 9

6

2

Manubrium width

18

0. 7

1.8

1.3

.05

.21

1.2-1. 4

16

-.220

3

Supradorsal length

18

1.8

2.6

2.1

.048

.20

2. 0-2. 2

10

.637

-.427

4

Stipe divergence

16

270

340

306

5.2

21

295-317

7

-.153

.405

-.078

5

Proximal stipe width

18

1.0

1. 3

1.2

.018

.08

1.1-1. 2

7

-.274

-.537

.013

-.132

Pseudisoqraptus

dumosus form

A

N.

Min.

Max.

Mean

sx

s

95S C. 1.

V

1

2

3

4

5 6

1

Sicular length

23

3.3

4.1

3.7

.046

.22

3. 6-3. 8

6

2

Manubrium width

22

1.4

2.1

1.7

.048

.23

.16-1.8

14

-.008

3

Manubrium length

22

1.0

1.6

1.4

.037

.17

1.3-1. 5

12

■ 431

.097

4

Stipe divergence

15

270

340

314

7

25

328-300

8

-.255

.069

.335

5

Proximal stipe width

21

0.8

1.5

1.1

.036

.17

1.0-1. 2

15

.076

-.454

.000

.132

6

Rhabdosome width

21

3.0

4.8

4.1

.11

. 5

3. 9-4. 3

12

.083

. 304

■ 587

.263

.218

Pseudisoqrptus dumosus form

B

N.

Min.

Max.

Mean

sx

s

953S C.l.

V

1

2

3

4

5 6

1

Sicular length

10

3.3

4.8

4.0

.14

.45

3. 7-4. 3

11

2

Manubrium width

10

1. 7

2.4

2.1

.077

.25

1.9-2. 3

12

■ 702

3

Manubrium length

10

1.1

1.6

1.4

.047

.15

1.3-1. 5

11

.478

.243

4

Stipe divergence

7

285

345

316

10

26

292-339

8

-.663

-.560

.080

5

Proximal stipe width

9

0.9

1.5

1.1

.057

.17

0.9-1. 2

15

.472

■ 702

.067

■ 606

6

Rhabdosome width

9

4.0

5.9

4.7

.23

.69

4. 2-5.2

15

.566

■ 842

.364

-.205

COOPER AND NI: PSEUDISOGRA PTUS

363

Pseudisoqraptus .jianqxiensis

N.

Min.

Max.

Mean

sx

s

95% C. 1.

V

1

2

3

4

5

6

1

Sicular length

12

4.6

6.0

5.2

. 13

.45

4. 6-5. 5

9

2

Manubrium width

11

2.8

3.3

3.1

.052

.17

3.0-3. 2

5

-.177

3

Manubrium length

11

1.2

1.7

1.5

.049

. 16

1.4-1. 6

11

.428

-.447

4

Stipe divergence

7

305

330

322

2.6

7

316-329

2

■ 970

-.430

■ 689

5

Proximal stipe width

9

1.1

1.5

1.3

.035

. ii

1.2-1. 4

8.5

-.378

.371

-.450

-.351

6

Rhabdosome width

10

5.0

6.2

.58

.11

.38

5. 5-6.0

7

.401

-.409

.05

.015

.455

Pseudisoqraptus

manubriatus harrisi

N.

Min.

Max.

Mean

3x

s

95% C. 1.

V

1

2

3

4

5

6

i

Sicular length

30

6. 8

0.0

8. 1

.13

. 74

7. 8-8. 4

9

2

Manubrium width

29

1.2

2.4

1.9

.06

.30

1. 8-2.0

16

. 190

3

Manubrium length

29

1.0

3.0

2. 1

.09

.51

1.9-2. 3

24

.138

.417

4

Free prox. length

29

1.0

4.0

2.1

. 14

. 73

1.9-2. 4

35

.597

.141

-.200

5

Stipe divergence

30

275

353

323

3

14

318-328

4

-.018

-.232

-.428

065

6

Prox. stipe width

30

2.4

3.4

2.9

0.5

. 26

2. 8-3.0

9

. 162

.377

.071

-.056

.192

7

Distal stipe width

19

2.6

4.5

3.1

.14

.53

2. 8-3. 4

17

.024

■ 630

.304

-.028

.348

Paeudisoqraptus manubnatus koi (Jimmy Creek)

N.

Min.

Max.

Mean

sx

s

95% C.l.

V

1

2

3

4

5

6

i

Sicular length

50

4.5

6.2

5.4

.055

.39

5. 2-5. 5

7

2

Manubrium width

50

0.7

2. 1

1.5

.047

. 33

1.4-1. 6

22

. 232

3

Manubrium length

50

0. 7

2.6

1.6

0.69

.49

1.5-1. 8

30

■ 461

■ 490

4

Free prox. length

50

1.0

2.3

1. 5

.046

.33

1.4-1. 6

22

.225

, 288

-.136

5

Stipe divergence

50

280

360

321

3.4

24

314-328

7

-. 145

-.664

-.532

-. 279

6

Prox. stipe width

50

1.4

3.0

2.0

.054

.38

1.9-2. 2

19

.213

-.595

-.401

-.290

. 721

7

Distal stipe width

50

1.9

3.3

2.4

.049

.34

2. 3-2. 5

14

.236

-.600

-. 328

-.403

.696

. 880

Pseudisoqraptus

manubriatus manubriatus

N.

Min.

Max.

Mean

sx

s

95% C. 1.

V

1

2

3

4

5

6

1

Sicular length

12

4. 3

5.9

4. 8

. 14

.50

4. 5-5.0

10

2

Manubrium width

13

1. 7

2.4

1.9

.09

. 33

1.7-2. 1

17

-. 179

3

Manubrium length

13

0.5

0.9

0.7

.05

.19

. 56-. 79

27

.425

-.470

4

Free prox. length

12

0.8

2.0

1.2

. 10

. 34

1.0-1. 4

28

. 768

.371

-.057

5

Stipe divergence

13

310

335

320

4

14

312-329

4

-.451

-. 188

-■ 579

-.112

6

Prox. stipe width

13

2.2

3.2

2.6

.09

.32

2. 4-2. 8

12

.189

.425

-.633

.484

■ 602

7

Distal stipe width

8

2.5

3.8

3.1

.2

.4

2. 7-3.4

13

.500

.459

-.633

.651

.687

.382

THE FIRST ARTICULATED FRESHWATER TELEOST
FISH FROM THE CRETACEOUS OF NORTH AMERICA

by LANCE GRANDE

Abstract. Chandlerichthys strickeri n. gen. et sp., represented by two articulated specimens, is described
from Middle Cretaceous deposits of the north slope of Alaska. This is the first articulated teleost species
positively of Cretaceous age that has been found in freshwater deposits of North America. Although
preservation is insufficient to permit detailed morphological description of the skull and caudal skeleton, it
appears to be an osteoglossomorph.

During August 1984 Mr Gary Strieker, a geologist for the USGS, discovered a nearly complete,
but poorly preserved, fish from freshwater deposits of Albian or Cenomanian age on the North
Slope of Alaska (text-fig. 1 ). The specimen (text-figs. 2 and 3), described here, was discovered on a
large sandstone block with another partial specimen (text-fig. 4). Mr Strieker spent several hours at
the locality looking for additional specimens but could find none. Because the specimens are
preserved as little more than thin carbon film, a detailed description of the skull and caudal
skeleton is not possible. The specimens were nevertheless thought to be worthy of description
because of their locality and geologic age. This locality is the first known freshwater Cretaceous
deposit in North America to produce an articulated teleost skeleton (with the possible exception of
Ostariostoma wilseyi Schaeffer, 1949, which is thought to be either Paleocene or Late Cretaceous).
The only other nearly complete articulated fishes of any kind described from Cretaceous freshwater
deposits of North America are two non-teleost species. Paleopsephurus wilsoni MacAlpin, 1947 and
Protoscaphirhynchus squamosus Wilimovsky, 1956. Paleopsephurus appears to be a polyodontid
(although Gardiner (1984) believes it to be the sister-group to Acipenseridae), and Protoscaphirhyn-
chus (described as an acipenserid) is a non-teleost actinopterygian of unknown affinity (also
discussed in Gardiner 1984).

SIGNIFICANCE OF FRESHWATER CRETACEOUS TELEOSTS

The Cretaceous is a very significant period for studies of the freshwater teleost fauna of North
America, because between Jurassic and Paleocene times there is a complete change in the fauna.
Prior to the Cretaceous the North American freshwater fish fauna is primarily non-teleost, and the
few teleosts present (i.e. ichthyodectids, incertae sedis) (Schaeffer 1967, Schaeffer and Patterson
1984) have not been found to be closely related to any Paleocene to Recent teleosts. The well-
documented Paleocene freshwater fish fauna is made up primarily of teleost species that belong to
modern groups such as Clupeidae (Grande 1982), Hiodontidae, Esocidae, Percopsidae, Cyprinoidea,
Gonorynchidae, and Osteoglossidae (Wilson 1980 and pers. comm.), and Ictaluridae (Lundberg
1975, p. 11). This newly discovered fish Chandlerichthys strickeri n. gen. et sp. represents a clue to
which freshwater teleosts were in North America between the Jurassic and the Paleocene.

METHODS

The type was examined wet (soaked in water) and in daylight or low, diffuse electric light. When
the specimen is examined dry or under bright microscope light, observed morphological detail

IPalaeontology, Vol. 29, Part 2, 1986, pp. 365-371. |

366

PALAEONTOLOGY, VOLUME 29

WOLF CREEK SQUARE LAKE

text-fig. 1 . Map showing locality (star) for Chandlerichthys strickeri n. gen. et sp.

text-fig. 2. Chandlerichthys strickeri n. gen. et sp., holotype (USNM 336567), standard length 108 mm, from
Cretaceous freshwater deposits of the north slope of Alaska.

GRANDE: ARTICULATED CRETACEOUS TELEOST

367

A B

text-fig. 3. C "handler ichthys strickeri n. gen. et sp.. A, enlarged photograph of head region of specimen in
text-fig. 2, b, drawing of lower jaw from text-fig. 3a showing teeth on dentary. ang, angular; art, articular;

de, dentary.

text-fig. 4. Chandlerichlhys strickeri n. gen. et sp., referred and only other known specimen (USNM 336567),
standard length, 57 mm. Originally from same block of matrix as holotype. Dashed line represents probable

body outline where specimen is broken.

decreases significantly (due to mica in the matrix, low relief of the bones, and low contrast between
fish and dry matrix).

Standard length was measured from the anterior tip of the snout to the posterior end of what
appears to be the third hypural. Preanal length was measured from the tip of the snout to the base
of the most anterior anal fin ray. All other counts and measurements were made as outlined by
Hubbs and Lagler ( 1949).

368

PALAEONTOLOGY, VOLUME 29

Osteoglossoidei Notopteroidea Lycopteridae Hiodontidae

All names for exclusively fossil taxa are preceded by a dagger symbol. The osteoglossomorph
classification used here is shown in text-fig. 5.

SYSTEMATIC DESCRIPTION

Division teleostei ( sensu Patterson and Rosen, 1977)

Supercohort osteoglossomorpha (sensu Patterson and Rosen, 1977)

Cohort, order and family incertae sedis
Chandler ichthys gen. nov.

Diagnosis. It is unlike any other known teleost in the following combination of characters: Very
deep bodied (body depth = 57% of standard length) with median fins set far back on body, caudal
fin slightly forked, with eighteen principal rays (1, 8, 8, 1) and a very small head and narrow caudal
peduncle; pectoral fin with numerous (20) but weakly developed rays.

Etymology. Chandler — after the Formation where the type specimen was discovered, ichthys— a fish.

Type and only species'. Chandlerichthys strickeri sp. nov.

Chandler ichthys stricken n. gen. et sp., text-figs. 2*4
Diagnosis. As for genus, only species; known size range 57-108 mm si.

Type specimen. USNM 336567 (text-figs. 2 and 3), a completely articulated fish poorly preserved as a carbon
film on a gray micaceous medium-grained sandstone. Standard length, 108 mm.

Referred specimen. USNM 336568 (text-fig. 4), a partial specimen preserved like holotype. Standard length,
57 mm.

Locality. Freshwater deposits of the Killik Tongue of the Chandler Formation (Nanushauk Group), Arctic

GRANDE: ARTICULATED CRETACEOUS TELEOST

369

Slope of north Alaska, latitude 68 13'7"N and longitude 153°25'45" on the south bank of the Colville River
(text-fig. 1).

Brosge and Whittington (1966) interpreted the sandstone, siltstone, shale and coal of the Killik tongue as
having been deposited in fluvial and related environments. Although several marine phases of the Nanushuk
Group have also been identified (May 1979), the fossil fish described here was collected among channel and
splay deposits in a fluvial sandstone within a meter or two of coal beds in either direction (Strieker, pers.
comm.). Geologic maps of the area are still in preparation by the USGS. Roehler (in press: fig. 10) illustrates
the type locality and refers to it as part of the Upper Delta Plain consisting of channels, splays, and coals.
Plant fossils indicate that the climate of the Alaskan North Slope during Albian time was subtropical to
warm temperate (Scott and Smiley 1979, p. 97).

Age. Albian, or possibly earliest Cenomanian.

Etymology, strickeri — after Mr Gary Strieker, the geologist who discovered the specimen.

Description (of holotype except where noted). Deep bodied, laterally compressed teleost. Total length 129 mm,
standard length 108 mm (referred specimen, 57 mm). Other measurements as percentage of standard length:
body depth (57%), head length (29%), prepectoral (29%), predorsal (64%), pre anal (77%), caudal peduncle
depth (14%), caudal peduncle length (21%), dorsal fin base (19%), and anal fin base (20%).

Meristic data: vertebrae 37 preural (18 caudal, 19 precaudal); ribs 17 pairs; principal dorsal fin rays 12;
dorsal pterygiophores 12; principal anal fin rays 14; anal pterygiophores 14; pectoral rays 20; pelvic probably
weak or absent (not preserved on specimen); predorsal bones 11; caudal fin 1, 8, 8, 1 (one unbranched and
eight branched rays in each lobe).

Median fins are relatively posterior in position, both well behind the midpoint of the body (text-fig. 2) (only
dorsal and upper lobe of caudal preserved on referred specimen). Anal insertion well behind dorsal insertion
and about vertical with posterior end of dorsal fin base. Principal dorsal fin rays are preceded by four or five
small unbranched accessory rays, and anal is preceded by two or three. Caudal fin is slightly forked with
rounded lobes. Vertebral column is arched over the abdominal area. There are two ural centra, the first of
which is slightly longer than the first preural centrum, and the second of which is reduced in size. Preservation
of scales was insufficient to allow their description, but they appear to be not as heavy as in Osteoglossidae.
No scutes or fin spines were observed. Eye appears large (base on preserved pigment) and the head and
caudal peduncle are very small in proportion to the rest of the body. The head has an anteriorly pinched-off
profile that is not due to distortion. This profile is also apparent in the referred specimen (text-fig. 4). There
appear to be a few caniniform teeth preserved in the lower jaw, which is deep and more osteoglossid-like than
hiodontid-like (text-fig. 3). Anterior arm of preopercle less than half the length of the vertical arm. Orbit
extends posterior to jaw articulation.

DISCUSSION

Of the known major teleost groups. Chandler ichthys appears to most closely resemble Osteoglosso-
morpha. As in primitive osteoglossomorphs (e.g. hiodontoids and the osteoglossoid Phareodus ),
there are sixteen branched caudal rays, posteriorly set median fins, caniniform teeth set in a deep
dentary, and a large eye. The moderately forked tail is similar to that of hiodontoids and Phareodus
and unlike Recent osteoglossoids, which all have a posteriorly rounded caudal fin. Chandler ichthys
also lacks any recognizable character that would place it in another teleost group (i.e. no scutes,
fin-spines, weberian apparatus, etc.). Remnants of scales are broken up with irregular edges,
suggesting that they may have been reticulate as in osteoglossoids. The general body shape of
Chandler ichthys is similar to that of the osteoglossoid Phareodus (e.g. Grande 1984, fig. II 34a) and
Yungkangithys (a deep bodied lycopterid illustrated in Chang and Chou, 1977, fig. 10). Unlike
Phareodus there is no enlargement of the anterior pectoral rays; unlike Yungkangichthys , the
predorsal bones point anterodorsally, and the vertebrae are not massive. The vertebral number
(39) is low for Osteoglossomorpha, but some fossil hiodontoids and Osteoglossomorpha incertae
sedis approach this number. Greenwood, 1970, lists lycopterids with as few as forty-three; Takai
1943, lists some lycopterid species with as few as forty. Kipalaichthys sekirskyi Casier 1965, from
the Lower Cenomanian of Zaire and placed in Osteoglossomorpha by Tavern (1979), also has
a low number of vertebrae (38-40). The arch of the vertebral column over the abdominal area

370

PALAEONTOLOGY, VOLUME 29

(text-fig. 2) is unlike other known osteoglossomorphs, and possibly related to the extremely small
head. Other osteoglossomorphs (e.g. Phareodus in Grande 1984, figs. II. 36a-h) have a nearly
straight vertebral column. Whether Chandler ichthys belongs in Osteoglossoidei or Notopteroidei
(Hiodontoidea + Notopteroidea) cannot be confidently determined based on the available specimens.
Admittedly, placement of Chandler ichthys even in Osteoglossomorpha rests largely on overall
resemblance and biogeography.

There is a possibility that the downturned anterior curvature of the vertebral column in the
holotype is pathological. This area of the vertebral column is missing in the second specimen. The
peculiar body outline with the very deep body, narrow caudal peduncle, and pinched-off head
profile is not likely to be pathological, though, because the second specimen (text-fig. 4) also shows
this.

Osteoglossomorpha, a group of 'primary freshwater fishes’ (Darlington 1957; Patterson 1981),
are represented today in North America by only two living species (Hiodon alosoides and H.
tergisus ), and no living Osteoglossoidea or Notopteroidea. The fossil record, however, is more
diverse. Well preserved Osteoglossoidea are abundant in Eocene freshwater deposits of the western
United States. With at least two species of Phareodus. Fossil Hiodontoidea are represented in
western North America by species described from Paleocene (Wilson 1980), Eocene (Cavender
1966; Wilson 1977, 1978; Grande 1979) and Oligocene (Cavender 1968) freshwater deposits. All of
the North American hiodontoids are in Hiodontidae, which are restricted to North America.
( Chetungichthys brevicephalus Chang and Chou (1977) from Late Mesozoic deposits of China was
identified as '?Osteoglossiformes, ?Hyodontidae’; due to the uncertainty of the original identification,
and to the lack of morphological evidence in type description, this species is not included in the
family here. Specimens were not available for this study.) The Hiodontidae are thought by most
ichthyologists (e.g. Greenwood 1970; Patterson and Rosen 1977; Taverne 1979) to be most closely
related to the fossil family Lycopteridae (text-fig. 5). The Lycopteridae are known from Upper
Jurassic to Lower Cretaceous time, and are known only from eastern Asia in lacustrine deposits
(Greenwood 1970; Takai 1943; Liu et al., 1963; Gaudant 1968; Chang and Chou 1976).

Additional material is needed for a more positive taxonomic placement of Chandlerichthys.
Unfortunately, it seems unlikely that such material will come to light in the near future, given the
difficult access to the type locality.

Acknowledgement. I thank Drs David Bardack and Colin Patterson for reading the manuscript and providing
me with their valuable comments. I also thank Mr Gary Strieker for discovering and sending me the specimen
described here, and Dr Dean Henrickson for originally telling me about the existence of the specimen.

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casier, E. 1965. Poisons fossiles de la Serie du Kwango (Congo). Ann. Mus. Royal de I'Afr. Centrale, Ser. 8,
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cavender, t. 1966. Systematic position of the North American Eocene fish ‘ Leuciscus ' rosei Hussakof. Copeia,
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chang, M. M. and CHOU, c. c. 1976. Discovery of Plesiolycoptera in Songhajiang-Liaoning Basin and origin of
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gardiner, b. g. 1984. 14. Sturgeons as living fossils. In eldredge, n. and Stanley, s. m. (eds. ). Living fossils,
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gaudant, j. 1968. Recherches sur 1’anatomie et la position systematique du genre Lycoptera (poisson
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— 1984. Paleontology of the Green River Formation, with a review of the fish fauna. Second Edition. Bull.
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may, F. E. 1979. Dinoflagellate and acritarch assemblages from the Nanushuk Group (Albian-Cenomanian)
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and rosen, d. e. 1977. Review of ichthyodentiform and other Mesozoic teleost fishes and the theory and

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Schaeffer, B. 1949. A teleost from the Livingston Formation of Montana. Amer. Mus. Novitates 1427, 1-16.

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distribution. Amer. Mus. Novitates 2796, 1 -86.

scott, r. a. and smiley, c. J. 1979. Some Cretaceous plant megafossils and microfossils from the Nanushuk
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Univ. Tokyo, Sec. II, 6, (1 1), 207-270.

ta verne, l. 1979. Osteologie, phylogenese et systematique des Teleosteens fossiles et actuels du super-ordre
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80, 2e Ser 43 (3), 1 68 pp.

wilimovsky, n. j. 1956. Protoscaphirhynchus squamosus, a new sturgeon from the Upper Cretaceous of
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wilson, M. v. H. 1977. Middle Eocene freshwater fishes from British Columbia. Life Sci. Contrib., Roval
Ontario Mus., 113, 1-61.

1978. Eohiodon woodruffi n. sp. (Teleostei, Hiodontidae), from the Middle Eocene Klondike Mountain

Formation near Republic, Washington. Can. J. Earth Sci. 15, 679-686.

— 1980. Oldest known Esox (Pisces: Esocidae), part of a new Paleocene teleost fauna from western Canada.
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Typescript received 21 March 1985
Revised typescript received 27 June 1985

LANCE GRANDE
Department of Geology
Field Museum of Natural History
Roosevelt Road at Lake Shore Drive
Chicago, Illinois 60605

THE NEMATULARIUM OF
PSEUDOCLIMACOGRAPTUS SCHARENBERGI
(LAPWORTH) AND ITS SECRETION

by CHARLES E. MITCHELL and KAREN J. CARLE

Abstract. The nematularium of Pseudoclimacograptus scharenbergi (Lapworth) is a three-vaned structure
derived from its hollow nema. The apex of the structure is sealed. The vanes are solid, lack a thickened rim, and
comprise thin, irregular lamellae that parallel the semicircular vane outline. Each lamella consists of a body
of anastomosing fibrils overlain by a dense outer pellicle. Although the thecae have a bandaged cortex, the
vanes lack cortical layers. The nematularium is strikingly irregular in shape and lamella geometry compared to
P. scharenbergi thecae. The structure of the nematularium is inconsistent with its secretion by an enveloping
epithelium but is explained well by the pterobranch model. Both the nema and the nematularium were probably
secreted externally to soft tissue (nematocaulus) confined within the lumen of the nema. A similar mode of
secretion could have produced most of the other structures derived from the nema of planktic graptolites. This
‘naked’ nematularium could not have added to the colony's buoyancy but would have added preferentially
to the viscous drag forces that slowed its rate of sinking. Thus, the nematularium and a variety of other
structures evolved by planktic graptolites may have helped these graptolites to maintain their preferred depth
in the oceans.

Palaeobiologists continue to be frustrated in their attempts to understand many of the most
fundamental features of graptolite biology. During the first one hundred years of study, even the
zoological affinities of graptolites were obscure. Kozlowski (1938, 1949, 1966), Bulman (1944-1947,
1955, 1970, and elsewhere), and Beklemishev (1970) have given graptolites a comfortable home
among the Hemichordata. Yet considerable debate remains about the closeness of this suggested
relationship with the pterobranch hemichordates in particular, and about how graptolites secreted
their skeletons. Recently, Andres (1977, 1980), Crowther (1978, 1981), Crowther and Rickards
(1977), and others have generated considerable interest in the pterobranch model of peridermal
secretion originally supported by Beklemishev (1970 and earlier) with their discovery that the cortical
layers in a wide range of graptoloids were deposited as distinct strips or bandages covering the
surfaces of the thecae. Alternatively, Kirk (1972), Urbanek and Towe (1974, 1975), Urbanek (1976,
1978), Bates and Kirk (1978), Urbanek et at. (1982), and others have argued in favour of a non-
pterobranch model in which all of the peridermal components, including the fuselli, were produced
beneath an enveloping epithelium (the extrathecal tissue model).

Relying on data from the ultrastructure of the thecae or thecal clathria and lacinia, the debate has
reached in impasse. The ultrastructure and patterns of growth of the nema and its associated
structures provide a critical test of the pterobranch and epithelial models. Several diplograptid
graptolites, including Pseudoclimacograptus scharenbergi { Lapworth), produced a three-vaned, float-
like organ (a type of nematularium) at or near the apex of the colony’s nema. Urbanek et al. (1982), in
their study of the Cystograptus vesiculosus nematularium, have proposed that the graptoloid nema
and the terminal nematularium were produced by an enveloping epithelium similar to that associated
with the thecae in the extrathecal tissue model. Crowther (1978, 1981) and Crowther and Rickards
( 1 977), however, note that the nema of most nematophorous graptolites was hollow and, as suggested
by Kozlowski (1971) and Hutt (1974), probably contained tissue (called the nematocaulus by Hutt)
capable of secreting the nema and associated structures. Indeed, a dual mode of peridermal secretion
of exactly this sort exists in the pterobranch Rhabdopleura (see Schepotieff 1 906, 1 907; Hyman 1 959).

IPalaeontology, Vol. 29, Part 2, 1986, pp. 373-390, pis. 28, 29.|

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PALAEONTOLOGY, VOLUME 29

The black rind of their stolon is secreted from within by the gymnocaulus (the organ that occupies the
central lumen of the stolon, and from which the zooids bud).

The pterobranch model and the extrathecal tissue model each lead to different expectations for the
formation and ultrastructure of the diplograptid nematularium. The pterobranch model, with its
double mode of secretion, implies that the graptoloid nema and nematularium must have been
produced by the nematocaulus from within as an external cuticle in like fashion to the pectocaulus of
Rhahdopleura. Ultrastructurally, the tissue of a nematularium should resemble that of the nema
rather than the fusel li and should include no multi-layered cortical tissue or cortical bandages since
these components of cortical periderm were produced by the cephalic disc of differentiated zooids.
Alternatively, the extrathecal tissue model implies that the nema and nematularium were secreted
from without by the external epithelium. The ultrastructure of the nematularium in this case should be
similar not only to the nema but also to the thecae.

Our intent in this paper is to report the results of our investigation of the peridermal structure and
ultrastructure of the nematularium of P. scharenbergi and to compare these observations with the
expectations generated by the different models of graptolite peridermal secretion. We also present a
revised interpretation of the function of these float-like structures.

MATERIAL AND METHODS

We obtained several complete and numerous fragmentary specimens of nematularia from a silty limestone
sample in the collections of the Museum of Comparative Zoology, Harvard University. The sample is from the
‘ Climacograptus band’ of the Balclatchie beds exposed in Laggan Burn, Ayrshire, Scotland. The three-
dimensionally preserved graptolite fauna of this Caradoc unit has been described by Bulman (1944-1947).
Bulman also recovered specimens of the nematularia, and tentatively referred them to the species Climacograptus
brevis Elies and Wood. Neither Bulman’s specimens nor ours were recovered attached to rhabdosomes. Their
referral to P. scharenbergi is based on reports of similar, but flattened, structures at the apex of the nema of this
species preserved in shales (Bulman 1964; see also text-fig. 1).

The limestone sample was soaked in an approximately 10% solution of hydrochloric acid for about one
month, with the spent solution being periodically exchanged for fresh as the carbonate dissolved. When all
reaction ceased the highly siliceous residue was carefully washed to remove the remaining Ca++, and a dilute
hydrofluoric acid solution was then added. After about two weeks the sample had become completely reduced to
an oozy sediment that was again carefully washed to remove the fine organic detritus. The freed graptolites were
pipetted from this residue. Additional details concerning the processing of graptolite-bearing limestone samples
can be found in Bulman (1944-1947) and especially in Wiman (1895).

Specimens used for light and transmission electron microscopy were dehydrated in a graded series of acetone,
embedded in Spurr’s Low Viscosity Resin, and sectioned on a Sorvall MT-2B Ultramicrotome with glass knives.
The thin sections were picked up on copper grids and viewed on a Zeiss EM-9 TEM. Light micrographs were
taken on a Zeiss Photomicroscope III using Panatomic-X film. Specimens for SEM study were mounted on
aluminum stubs using gum tragacanth, coated lightly with gold/palladium, and examined at 20 kV using an
AMRAY 1000A SEM. Micrographs were taken on Polaroid 4X5 land film type P55 Positive-Negative, handled
according to package directions.

DESCRIPTION OF THE NEMATULARIUM

Nematularium form. The nematularium consists of three vanes radiating at roughly 120° to one
another from the central nema (text-fig. 2; PI. 28, figs. 1, 3-6; PI. 29, fig. 2). The vanes are very thin and
delicate. The overall size of the nematularium varies from specimen to specimen but ranges up to
about 1 -5 mm in width and 5 0 mm in length. The proportions of the structure are also somewhat
variable. The length; breadth ratio ranges from about 5:1 to approximately 2-5:1. Individual vanes
within a nematularium are generally all of different lengths: that is, they extend to different distances
down the nema. At the apex of the structure all three vanes unite to form a triangular cap that
completely occludes the end of the nema (PI. 28, fig. 1). The nematularium has a central lumen
(40-45/xm in diameter) that corresponds to the lumen of the nema (PI. 28, figs. 4, 6; PI. 29, figs. 1 , 2).

MITCHELL AND CARLE: SECRETION OF GRAPTOLITE NEMATULARIUM

375

text-fig. 1 (left). Complete rhabdosome of Pseudoclimacograptus scharenbergi showing a nematularium at the
tip of the nema, approx, x 2 (reconstructed in part from Bulman 1964, hg. 5c).

text-fig. 2 (right). P. scharenbergi nematularia (sample location and horizon as in Plate 28). a, SEM of tip of
a slender nema showing terminal bulb and two lateral swellings, x 60 (specimen accidentally destroyed), b ,
nematularium, MCZ 9432, viewed in transmitted light, x 33 (specimen subsequently sectioned for transmission

electron microscopy).

The vanes themselves are solid and exhibit no traces of being the collapsed remnants of a globular,
hollow vesicle (PI. 29, fig. 2).

Under transmitted light (text-fig. 2b) the vanes show narrow, irregular growth lines that more-or-less
parallel the outline of the vane and are sub-parallel to the length of the nema. The growth lines are
roughly concentric about what appears to be their point of origin from the nema. These centres are at
different locations along the nema for each of the three vanes and are further from the apex of the
structure the longer the vane. The concentric arrangement of the thin growth lines is commonly
interrupted by variations in width of the growth increment, by pinching out of individual lamellae,
and in some cases by what appear to be periodic shifts along the nemal axis of the centre about which
the growth lines are concentric. Thus, the locus of most active growth in an individual vane appears to
have shifted abruptly from time to time. As Bulman (1944-1947, p. 65) noted, the edge of each vane is
markedly more opaque but not thicker than the remainder. This condition contrasts sharply with the
situation in the nematularium of Cystograptus penna and C. vesiculosus (Jones and Rickards 1967;
Urbanek et al. 1982) where the vanes have a thickened rim.

Individual growth lamellae are narrow compared to the width of fuselli in the thecae of P.
scharenbergi. They average 18 pm in width (range 10-30 pm) while the fuselli of distal metathecae
have an average width of 70 pm (range 50-120 pm). In addition to being much narrower than
the fuselli the growth bands are also much longer. Individual bands commonly extend from one end

376

PALAEONTOLOGY, VOLUME 29

of a vane to the other, over a distance of as much as 5 mm. Apart from the similar microfuselli
of the C. vesiculosus nematularium, we know of no other peridermal structures in which the
constituent growth bands are even approximately of the proportions of these nematular growth
lamellae. A potential exception, but as yet unproved, may be the growth lamellae of the nema itself
(see Berry 1974).

Among graptolite colonial structures, nematularia are highly atypical. Both in the arrangement of
the constituent growth lamellae and in the overall form of the structure, they are strikingly less
regular than are the thecae and other principal structures of graptoloid rhabdosomes.

Nematularium growth stage. Our collections include one specimen that we interpret as an early
growth stage in the formation of the P. scharenbergi nematularium (text-fig. 2a). This specimen is a
small distal fragment of a nema, the tip of which is bulbous and may be sealed. It also bears two
localized swellings located a short distance down the nema, on nearly opposite sides. The walls of the
swellings and the bulbous tip appear to be thin and somewhat collapsed; they consist of narrow
growth lamellae that parallel the outline of the swellings. Structures like these were described as early
stages in the growth of the similar virgular apparatus of Climacograptus parvus by Ruedemann
(1908). Unfortunately, our specimen was destroyed accidentally during handling of the SEM stub on
which it was mounted.

Nematularium ultrastructure. Under SEM examination the vanes appear slightly shrunken and
cracked. The surfaces of the nematularium are irregularly pitted, probably as a result of their
diagenetic history. Where well preserved the vane surfaces reveal subparallel fibrils (about 0- 1 5-0- 1 8
/i m in diameter) that, like the growth lamellae, are concentric with the edge of the vane. Also present
are minute oval pits whose long axis is parallel to the fibrils. These pits are similar to those associated
with sheet fabric (Crowther 1981 ).

The nematularia exhibit no traces of either cortical deposits in general or bandaging in particular.
The broken ends of several nematularia examined with the SEM reveal the layered fibrillar structure
of the periderm (PI. 28, figs. 2, 6). Individual growth lamellae are crescentic or chevron-shaped,
overlapping, and comprise sub-parallel, anastomosing fibrils. The fibril diameter is approximately
015-0T8 jum. TEM cross-sections corroborate this picture of lamella geometry and show that each
growth lamella consists of a body of a loosely-packed, fibrillar mesh enclosed in a thin, electron-dense
outer pellicle (PI. 29, fig. 3). Under SEM examination this outer pellicle is seen to consist of densely
packed, sub-parallel fibrils.

A comparison of cross-sections of the nema just proximal to the nematularium (PI. 29, fig. 1 ) and of
the nematularium proper (PI. 29, fig. 2) confirms that the vanes are produced by a progressive
elaboration of the walls of the nema. Both nema and nematularium enclose a relatively spacious

EXPLANATION OF PLATE 28

Figs. 1-7. Pseudoclimacograptus scharenbergi (Lapworth) nematularia, isolated from silty limestone of the
‘ Climacograptus band’, Laggan Burn, Ayrshire, Scotland. 1,3,6, MCZ 9430: I, apical view showing sealed
apex where the three vanes join at about 120°, x 190; 3, lateral view showing blunt apex with vanes tapering
proximally, and third vane and nema broken away, x 47; 6, enlarged view of broken proximal end showing
overlapping, chevron-shaped growth lamellae in end view of broken vertical vane above the triangular central
lumen, x 470. 2, 4, MCZ 9431: 2, high magnification view of surface near proximal end of specimen in fig. 4,
showing subparallel arrangement of fibrils on outer surface (= pellicle) and more irregular, mesh-like
arrangement of fibrils below, x 5200; 4, proximal view showing merging of nematularium with nema (note
three-lobed central lumen), x 230. 5, 7, MCZ 9429: 5, lateral view showing irregular surface and no signs of
cortical bandaging, x 72; 7, high magnification view of vane surface and edge in upper left area of specimen,
showing parallelism of fibrils and vane edge (at top of figure) as well as numerous minute elliptical pits like
those typical of sheet fabric (large irregular pits and hummocks are probably preservational artifacts), x 1 500.

All SEMs.

PLATE 28

MITCHELL and CARLE, Pseudoclimacograptus nematularium

378

PALAEONTOLOGY, VOLUME 29

lumen, 40-45 jum in diameter. There is a great similarity between the nematularium growth lamellae
and those of the nemata studied by Berry (1974, especially pi. 8).

The structural basis of the growth lines visible in the vanes under transmitted light is apparent in
TEM cross-sections. The three regions between the vanes consist of approximately four growth
lamellae. In contrast the vanes consist of a large number of growth lamellae. In their broader portions
we estimate (the irregular lamellae are difficult to count accurately) that the vanes are comprised of
thirty or more growth lamellae. Plate 29, fig. 3 shows the junctions of several lamellae (arrowed);
these junctions are staggered at intervals, and it is this overlap that results in the appearance of
growth lines when the vanes are viewed in transmitted light. Ideally, a vane seen in cross-section
resembles a stack of bowls that become narrower and deeper towards the top of the stack. The
innermost growth lamellae, adjacent to the central lumen, are broadly crescentic with a curvature
similar to that of the lumen wall. Growth lamellae located successively further out into the vanes
become more chevron-shaped and overlap one another extensively.

Not all lamellae in the nematularium have a pellicle of the same thickness. Those of the outermost
four or five lamellae in the vanes and all lamellae of the nema have a pellicle that is substantially
thicker than that of the lamellae found in the inner portions of the vanes. The outer lamellae, with
their thicker pellicle, usually extend about one-third the circumference of the nematularium
(PI. 29, fig. 2); they make up most of the thickness of the structure between the vanes and reach nearly
completely around each vane. In the axial area of a vane, adjacent to the lumen, the lamellae have a
thin pellicle and are asymmetrical; they occupy only about one-sixth of the circumference of the
lumen and extend from the region between the vanes to just past the vane axis, towards the next inter-
vane region. An idealized reconstruction of this structure is illustrated in text-fig. 3.

A GROWTH MODEL FOR NEMATULARIA
Growth of the P. scharenbergi nematularium

We propose that the structure of the nematularium indicates that it was secreted by an organ, the
nematocaulus, that lay within its central lumen and within the nema. We further propose that this
secretion occurred in distinct pulses. Six principal factors dictate this mode of secretion:

1 . Growth lamellae are irregularly offset and change geometry markedly from the inner to the
outer portions of the nematularium vanes.

2. The number of growth lamellae in the vanes and in the regions between the vanes are greatly
different, yet the outermost lamellae in the vanes enclose most or all of each vane and lap on to the
intervane areas.

3. The outer pellicles of the outermost several lamellae in the vanes and in the regions between the
vanes are markedly thicker than those in the inner portions of the vanes. However, they appear
identical to those of the nema just below the nematularium and to the lamellae of the nemata
illustrated by Berry (1974, pi. 8).

4. This zone with thicker pellicles coincides with the more opaque edges of the vanes, which appear
to be present in all nematularia regardless of the size of the vanes or the size of the structure as a whole.

5. The apex of all of the nematularia examined are sealed, regardless of the state of maturation of
the structure.

EXPLANATION OF PLATE 29

Fig. 1 -3. Pseudoclimacograptus scharenbergi (Lapworth) nematularium. MCZ 9432, sample location and
horizon as in Plate 28. 1, light micrograph of cross-section of nema just proximal to base of nematularium,
x 650. 2, light micrograph of cross-section of proximal end of nematularium showing arrangement of growth
lamellae surrounding its central lumen, x 1150. 3, TEM of portion of vane of nematularium in cross-section,
x 10000. pe, pellicle.

PLATE 29

MITCHELL and CARLE, Pseudoclimacograptus nematularium

380

PALAEONTOLOGY. VOLUME 29

text-fig. 3. Reconstructed and idealized cross-section of the Pseudoclimacograptus
scharenbergi nematularium showing the structure and geometry of growth lamellae, approx,
x 250 (based on cross-sections illustrated in Plate 29).

6. In none of our specimens is the external surface covered by any secondary (cortical) peridermal
material.

Text-fig. 4 presents schematically our interpretation of the growth of the P. scharenbergi
nematularium. The outer, more opaque lamellae were derived directly from the pre-existing nema
during the early phases of nematularium growth. This opaque rim comprises lamellae with a
thick pellicle and appears to be present on all vanes throughout all stages of nematularium growth.
Growth commenced with the secretion of small, wedge-shaped lamellae in three linear zones arrayed
around the circumference of the nema and between the epithelium of the nematocaulus and the pre-
existing periderm. As each new layer was secreted, it fused with the last-secreted layer in inter-vane
regions. The formation of new lamellae pushed the pre-existing lamellae outwards with the result that
the periderm between the inter-vane areas buckled outward to form the vanes. As succeeding layers
were added internally, each outer layer was pushed further outwards, stretched and buckled to an
even greater extent. Why did the layers fuse only in the three inter-vane areas? These areas may have
been the most active sites of periderm secretion or the sites where secretion occurred first at a given
level of the nematularium. The newly secreted and still unpolymerized periderm fused with the
previously secreted layer before it began to push the previous layer outward and before secretion was
initiated in the vane areas.

This scheme requires only the existence of a simple secretion-inducing morphogen that diffused in a
proximal-to-distal direction along the axis of the nematularium to regulate growth. The immature
nematularium pictured in text-fig. 2 a shows that all three vanes originated along a single spiral
pathway and could, therefore, have originated from a single morphogen gradient. The configuration

MITCHELL AND CARLE: SECRETION OF GRAPTOLITE NEMATULARIUM

381

of vane lengths, widths, and level of origin along the nema, together with their positioning at about
1 20° to one another shows numerous parallels with the phenomena of phyllotaxis. This configuration
indicates that the apparently high degree of order exhibited in the nematularium’s form may have
arisen, as it does in phyllotaxis, as a forced consequence of the physical constraints of growth and the
requirement that elements of finite size be added where there is sufficient room for them to grow
(Thompson 1948; Wardlaw 1953; see also Gould and Katz 1975). Thus, we need not invoke any ad
hoc or particularly complex regulatory mechanism to explain the nematularium’s growth.

text-fig. 4. Idealized cut-away views of the Pseudoclimacograptus scharenbergi nematularium illustrating its
derivation from the nema and subsequent growth by the addition of new lamellae in generative zones beneath the
vanes. The boundaries of approximately every second lamella are shown. Lamellae with similar added
patterning were formed synchronously. The longitudinal stripes added to the outer lamella emphasizes its three-

dimensional form and do not indicate growth lines.

Application of the model

If our model for nematularium growth in P. scharenbergi is correct it should also be applicable to
most or all of the other float-like nematularia found among the nematophorous graptolites. We base
this conclusion on two lines of reasoning:

1. Nematularia occur sporadically among a wide variety of graptolites including the dendroid
Rhabdinoporaflabelliformis (Bulman and Stormer 1971), anisograptid dendroids (Jackson 1974), and
in representatives of all of the graptoloid families (see Ruedemann 1904, 1908; Bulman 1964; Muller
and Schauer 1969; Kozlowski 1971; Rickards 1975; Finney 1979). This wide but scattered
occurrence of nematularia means that, although they evolved independently in several different
lineages, the capacity to develop these structures was a general, shared feature of the nematophorous
graptolites as a group.

2. In reconstructing the mode of secretion of the P. scharenbergi nematularium we have based
many of our inferences on several fundamental similarities between the anatomy and skeletal
structures of graptolites and pterobranchs. If these similarities are indeed true homologies, as we
believe them to be, then the proposed mode of secretion should be a widely shared capacity among the
graptolites — a capacity based on the nature of the nema of the nematophorous graptolites.

In all but a very few cases, nematularia are known only from small numbers of non-isolated,
flattened specimens. Although we can point out some features of these organs that are consistent with
our explanations, their structures and patterns of growth are not known well enough to permit us to
determine the details of their morphogenesis. Thus, they do not constitute a test of our model. Only
two other nematularia have been studied from isolated preparations.

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PALAEONTOLOGY, VOLUME 29

Finney (1979) described a vesicular structure associated with a Dicellograptus specimen from the
middle Ordovician Athens Shale in Alabama; Finney (pers. comm.) has since discovered additional
specimens of this nematularium in the Athens Shale. The structure was a hollow, apparently single-
walled globe that was attached to the end of a somewhat expanded, hollow nema of a young
Dicellograptus. The minute vesicle was only 0-4 mm in diameter, had no external opening, and lay
about 0-8 mm from the apex of the prosicula. This configuration agrees well with the mode of
secretion that we have proposed for the P. scharenbergi nematularium. It is of the same magnitude
as the hollow nodes developed in the early growth stage of the nematularium described above and
likewise may have formed externally, around a localized enlargement of the nematocaulus. The
periderm of the Dicellograptus nematularium appears to be structureless because it formed by a
simple ballooning outward of the layered nema, without the secretion of additional periderm to form
a more elaborated structure like that of the P. scharenbergi nematularium. As Kozlowski (1971) and
Finney (1979) noted, the ‘attachment discs’ of many dendroid and dichograptid species described by
Ruedemann probably represent hollow vesicles of this sort.

It is more difficult to interpret the mode of growth of the Cystograptus vesiculosus nematularium.
Although Urbanek et al. (1982) believed that it provided an example of secretion beneath an
epithelial membrane, they did not give any detailed reconstruction of how this structure, with its
thickened rim, grew. Since this apparatus appears to have no central lumen in the region they studied,
it must have been formed by a mechanism somewhat different from that which we envisage as
responsible for most other graptolite nematularia.

Urbanek et al. (1982) concluded that the ultrastructure of both the vanes and the thickened rims of
the C. vesiculosus nematularium was quite distinct from the ultrastructure of the diplograptid nema.
From this they inferred that the nematularium was not a highly modified derivative of the nema but
rather a replacement for the nema. If this is true then it may not be unduly troubling that this
nematularium type has a different morphogenetic pattern from that of P. scharenbergi , Finney’s
Dicellograptus specimens, and nematularia of the scopaeculare type (see Muller and Schauer 1969, for
a classification of nematularium forms), all of which are unambiguously derived from a normal and
intact nema.

A solution to the exact mode of secretion of the C. vesiculosus nematularium must await more
detailed information about its growth stages, its relationship to the nema and prosicula, the timing of
growth, and of its enclosure by the upward growing rhabdosome. The form of the C. vesiculosus
nematularium is not easily explained by the extrathecal tissue model either. The thickened rim of the
vanes was probably present throughout the ontogeny of the apparatus (Jones and Rickards 1967
observed thickened rims on the immature vanes of C. penna). Accordingly, it seems unlikely that the
nematularium could have been secreted by external addition of growth increments without also
undergoing extensive and continuous remodelling. The cross-sections figured by Urbanek et al.

( 1 982) show no signs of such remodelling. Data from other species that possess a nematularium with
thickened rims and no central nema (such as Petalograptus speciosus and others with an apparatus of
the vinculare and bullare type; see Kozlowski 1971) may also be relevant.

IMPLICATIONS FOR THE MODE OF PERI DERMAL SECRETION

In the introduction we outlined the features of the two models of peridermal secretion that provide
the best explanation of the data available on colony form and construction (see text-fig. 5). Our data
on the growth of the Pseudoclimacograptus scharenbergi nematularium are inconsistent with the
extrathecal tissue hypothesis but fit well with the pterobranch hypothesis. If our model is
corroborated in studies of other nematularia, we believe that it, taken together with the data on
cortical bandaging described by Crowther and Rickards (1977), Crowther (1978, 1981), and Andres
(1977, 1980), will require the extrathecal tissue hypothesis to be abandoned as a general explanation
for graptolite peridermal secretion. In this section we develop the argument that underlies this
conclusion.

MITCHELL AND CARLE: SECRETION OF GRAPTOLITE NEMATULARIUM

383

text-fig. 5. Ideogram of relationships between the graptolite zooids and the
rhabdosome of a pseudocliinacograptid as predicted from a, the extrathecal
tissue hypothesis and b , the pterobranch hypothesis. The rhabdosome is shown
in cross-section, as is the nematularium in b. The prosicula and lower portion
of the nema are black; thecal periderm is indicated by chevroned fuselli and soft
tissues are stippled. The median septum is omitted for clarity, a, zooids
reconstructed as bryozoan-like, according to the suggestions of Urbanek (1978);
note that the nema is a solid rod the secretion of which is unrelated to the
funiculus-like stolon of the siculozooid; the nematularium is enveloped in
secretory extrathecal tissue and its primary periderm coated with cortical
bandages, b, zooids are reconstructed as pterobranch-like; the nema is secreted
by an internal extension of the stalk of the siculozooid; the nematularium is
‘naked’ and bears no secondary cortex.

Like all diplograptids the rhabdosome of P. scharenbergi has a thick cortical layer covering the
fusellar periderm and obscuring the fuselli. Unfortunately, preservation in our Balclatchie graptolite
sample shows a strong bias against the robust species with their thick cortex. Colonies of
Amplexograptus leptotheca , Climacograptus brevis, and the nematularia are moderately well
preserved, but those of larger species, such as Orthograptus apiculatus and P. scharenbergi , are poorly
preserved. Both A. leptotheca and C. brevis exhibit clear cortical bandaging but all the rhabdosome
surfaces of the P. scharenbergi specimens we examined are corroded and fractured. The cortical
structures have been obliterated for the most part, although a few specimens exhibit vague traces of
bandaging. Broken edges of the thecae reveal that diagenesis has destroyed all traces of the fibrillar
nature of both the fusellar and cortical tissues.

Crowther (1981) observed bandaging in Bulman’s P. scharenbergi material (particularly in P. s.
stenostoma). The closely related species P. sp. aff. P. caudatus, from strata of the C. pygmaeus Biozone

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PALAEONTOLOGY, VOLUME 29

text-fig. 6. Composite SEM of young rhabdosome of Pseudo-
climacograptus sp. aff. P. caudatus (Lapworth) (despite its nearly
straight supragenicular walls, this species has a strongly zig-zag
median septum and an early astogeny identical to that of P.
scharenbergi ), MCZ 9433, from lower Viola Springs Formation
(Alberstadt’s 1973 section O, 47 m above outcrop base), upper
Climacograptus pygmaeus Zone (probably coeval with P. linearis
Zone of Welsh succession). Note strikingly bandaged cortex with
nearly all bandages radiating from thecal apertures or from the
sicular aperture; note also that some bandages extend across the
apertural selvage on to the infragenicular wall, x 60.

(Caradoc) in the Viola Springs Formation of Oklahoma, shows a strikingly bandaged cortex (text-fig.
6). Andres (1980) also figured micrographs of a Pseudoclimacograptus species that is strongly
bandaged. In both of these species, bandages densely coat the entire periderm and virtually all
bandages radiate from a thecal aperture or from the sicular aperture.

There is a sharp contrast between the periderm of the P. scharenbergi and other diplograptid
nematularia on the one hand, and the periderm of the corresponding rhabdosomes on the other.
(Urbanek et a/. 1982 did not report on the ultrastructure of the thecate portion of the C. vesiculosus
rhabdosome, but the peridermal fabrics of its nematularium were like those described here.) The
major differences include the following:

1. Nematularia appear to be either structureless or to consist of thin, irregular, microfuselli-like
growth increments of great length. The thecal fuselli, in contrast, are relatively much shorter and
extend only one half the circumference of the theca.

2. Nematularia completely lack cortical deposits in general and bandaged cortex in particular.
Diplograptid rhabdosomes, including those of P. scharenbergi , have a thick, multi-layered, and
usually bandaged cortex that overlies the notably regularly arranged fuselli.

3. Growth lamellae of nematularia are formed approximately parallel to the longitudinal axis of
the structure and are extremely long ( up to several millimetres). In contrast, the fuselli of diplograptid

MITCHELL AND CARLE: SECRETION OF GRAPTOLITE NEMATULARIUM

385

thecae and median septa are short (of the order of 0-5 mm) and are formed nearly perpendicular to the
longitudinal axis of these structures.

4. Nematularia are markedly irregular, both in their overall size and shape and in the arrangement
of their constituent growth lamellae. Graptolite colonies and their constituent thecae exhibit
outstanding regularity in their form (shape, growth gradients, branching pattern, and the like) and
arrangement of fuselli.

In summary, the nematularia and rhabdosomes differ in the suite of peridermal tissues that
constitute the structure, in their geometric arrangement, and regularity. The existence of such
differences could not have been predicted from the extrathecal tissue model of graptolite peridermal
secretion. On the contrary, this model leads one to expect more substantial similarities than we
observed. For example, in an effort to reconcile the presence of cortical bandages with his extrathecal
tissue hypothesis, Urbanek (1978) postulated that the bandages were a low mass means of
strengthening the rhabdosome. Yet, despite the probability that a means for producing a high
strength, low mass periderm would have been at a similar or even greater premium on the P.
scharenbergi or C. vesiculosus nematularium compared to the rhabdosome proper, the nematularia
lack a bandaged cortex or any cortex at all. We suggest that the striking contrasts outlined above are
not compatible with the hypothesis that both the rhabdosome and nematularium were secreted in the
same manner under a common extrathecal membrane.

However, these contrasts between the fabric, structures, and peridermal tissues present in the
nematularia and the thecate portions of the rhabdosome are precisely what we should expect given
the pterobranch hypothesis. In this case the rhabdosome is the product of a dual mode of secretion.
The thecate part of the rhabdosome was secreted by the mobile, pterobranch-like zooids and so
exhibits fabrics, tissues, and geometries reflective of this mode of origin: regularly arranged, short
fuselli deposited around the growing edge of the lengthening thecal tube; cortical tissues deposited
secondarily in parallel-sided bandages comprised of densely packed fibrils that are themselves parallel
to the edge of their bandage. The nema and nematularium were secreted by soft tissue associated
solely with this organ and so exhibit a different set of fabrics, tissues, and geometries reflective of this
mode of origin: highly elongate, somewhat irregular lamellae that parallel the length of the vanes and
the nema; absence of secondary (externally added) cortical deposits; lamellar geometries suggestive
of internal formation adjacent to the nematularium’s lumen. Andres’s (1980) observations of
bandaging on the nema of diplograptids is not in conflict with our proposals but rather indicates that
secondary, cortical deposits may be added to the outside of the nema in regions near the thecate
portion of the rhabdosome during colony growth.

Rickards (1975), Rickards and Crowther (1978), Crowther and Rickards (1977), and Crowther
(1978, 1981) have suggested that the nematocaulus may have extended from the tip of the nema to
cover its outer surface. This also does not seem possible in the case of the P. scharenbergi nematularia
at least. As we noted above the apex of the nema was apparently sealed during the entire ontogeny of
the nematularium.

FUNCTION OF THE NEMATULARIUM

The nematularium growth model that we suggest requires a dramatically different view of the
function of these structures than has previously been considered. The most commonly accepted
hypothesis is that the nematularium functioned as a float and was either hollow and gas-filled (as
seems plausible for the organ described by Finney ( 1 979) or was solid and enveloped in vacuolated or
ciliated soft tissue (Rickards 1975; Urbanek el al. 1982). Our model of the P. scharenbergi
nematularium postulates a naked structure with a relatively small amount of soft tissue confined to its
central lumen. Urbanek et ah (1982, p. 225) stated that naked 'floats’, as implied by the radical
pterobranch hypothesis of Andres (1980), could not have aided the buoyancy of the colonies; this
applies equally well to our model. Given Andres’s model, Urbanek et al. (1982) suggested that
nematularia could only have functioned as stabilizers to prevent rotation or as a kind of sail. They
further suggested, and we agree, that neither proposal seems particularly plausible. However, a
different function is likely.

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PALAEONTOLOGY, VOLUME 29

As a consequence of their small size and the low velocities at which they probably moved through
the water column (as is common for zooplankton, many of which follow a vertical diurnal migration
through the photic zone; see Banse 1964), graptolite colonies must have lived in a world
dominated by the high viscous forces characteristic of hydrodynamic situations with low Reynolds
number. The magnitude of such forces are determined by size, surface area, and shape. Under these
circumstances, body forces, such as the inertial forces generated by the acceleration of the colony’s
mass due to gravity, will be relatively low or even negligible. Hence, buoyancy (essentially a body
force of sign opposite to that of the gravitational force) may also have been of little importance in the
dynamics of colony motion and stability. Drag forces are the dominant forces in highly viscous
situations. (For a qualitative review of these relationships see Shapiro 1961.)

The extremely thin-vaned nematularium must have contributed relatively much more to the
colony’s surface area than to its mass. The frictional drag experienced by a colony is a consequence of
shear forces that arise due to motion through a viscous fluid. These forces are proportional to the
surface area of the colony and tend to retard motion. Sinking occurs as a consequence of gravity,
which generates an inertial body force proportional to the mass of the colony. Thus, the effect of the
addition of a nematularium must be to preferentially increase the colony’s frictional drag. Drag for
planktic colonies would enhance depth stability by tending to slow movement up or down in the
water column. Erdtmann (1976) and Kaljo (1978) (following on from the earlier suggestions of Berry
1962, among others) provided substantial evidence from the facies associations of graptoloids which
indicated that they lived a depth stratified existence. Given this ecology, a mechanism that allowed
planktic graptolites to maintain their preferred depth (as opposed to simply remaining afloat in the
pleuston) by utilizing passive drag may have been of considerable ecological and evolutionary
significance to graptoloids.

It is possible to estimate the mass and viscous drag that a nematularium would have contributed
to a mature P. scharenbergi colony, given a few simple assumptions about the velocity of colony
motion and periderm density. Unfortunately, we lack sufficient information about graptolite
palaeobiology and palaeoecology to define criteria by which to judge the significance of the drag
enhancement when simply computed in this isolated fashion. Accordingly, we have not undertaken
these calculations.

Considerable qualitative support for the suggestion that drag enhancement was the primary
function of nematularia can be deduced from among the range of graptolite colonial structures.
Many graptolites display organs that must have added principally to colony drag. In several cases
these novel structures could scarcely have had any other function and do not appear to be an outcome
of constructional constraints on form (i.e. they do not appear to be primarily a reflection of the
Bautechnischer aspekt of form, in Seilacher’s 1970 terminology).

Several multi-branched, horizontal dichograptids such as Loganograptus logani , L. kjerulfi, and
Tetragraptus headi possess a central webbing that connects the proximal regions of their many stipes
(summarized by Bulman 1964, 1970). Lenz (1974) described a similar membrane-bearing
rhabdosome of Cyrtograptus. In the anisograptid Clonograplus callavei , the sides of the stipes are
drawn out as lateral flanges. Specimens of Rhabdinoporaflabelliformis often possess an apical bundle
of fibres (Bulman 1972) corresponding to a much-divided nema (Hutt 1974 described a young growth
stage of either Adelograptus hunnebergensis or C. teneUus that exhibited a nema divided into three
separate branches) as do several Silurian diplograptids grouped by Muller and Schauer (1969) as the
scopaeculare flotation apparatus.

Speculation that the membrane structures strengthened the rhabdosome, or that these and the
scopaeculare- type nematularia were covered by vacuolated or ciliated soft tissue (Bulman, 1964)
remains possible, but it is certain that these structures would have added preferentially to the viscous
drag forces acting on the colony and, accordingly, would have slowed vertical motion. The
problematic virgellarium of Linograptus posthumus (Urbanek 1963), and the large proximal spines
and webbed spines of Climacograptus bicornis , C. longispinus , C. papilio , C. ensiformis, and others, as
well as the large paddle-shaped vane of Monograptus pala (see Bulman 1964; Riva, 1974) must have
had similar effects. Furthermore, as Bulman (1970, p. V94) noted, if the functional significance

MITCHELL AND CARLE: SECRETION OF GR APTOLITE NEMATULARIUM

387

(assuming they were adaptations in the narrow sense) of these diplograptid and monograptid
proximal-end structures was to aid buoyancy, the colonies must have possessed a reversed
orientation compared to that usually considered likely for graptoloids (the thoughts of Kirk 1969 not
withstanding; see Rickards 1975 on her suggestions). If these structures served primarily to enhance
drag and depth stability, their proximal position imposes no such inversion.

Finally, a variety of suggestions have been offered to account for the independent evolution of
retiolitid colony forms. Kirk (1979) stressed the importance of selection for reduction in rhabdosome
mass as an aid to increased mobility. Other plausible suggestions include selection for an
economizing of the energy and material expended during periderm construction. Regardless of
whether or not these suggestions are correct, again it is certain that the reduction of the colony’s
periderm to a series of rods would also have had a great effect on the ratio of frictional drag forces
to inertial body forces. This effect arises from the inescapable negative allometry between surface
area (proportional to frictional drag forces) and volume (proportional to mass and so to inertial
forces). Hence, the relative increase in surface drag forces compared to reduction in periderm
mass would greatly retard the colony’s rate of sinking. The development of a lacinia must have
further added to this effect, as both Kirk (1972) and Rickards (1975) noted, yielding immobile
holoplanktic colonies.

In summary, we believe that a wide variety of characteristics of both dendroids and graptoloids can
be interpreted as primarily having affected colony drag. These include: 1 , evolutionary trends toward
peridermal reduction or reduction accompanied by formation of clathria and lacinia; 2, astogenetic
shape changes which accompanied the progressive elaboration of spines and lacinia or the
development of a nematularium; and 3, the frequent acquisition of one of a wide range of structures
(spines, genicular flanges, clathria, lacinia, proximal webs and vanes, and a variety of nematularia)
that preferentially add to a colony’s surface area. These features of graptolite colonies evolved not
only very commonly, but also independently by convergence and parallelism in many different
lineages. All of these features must have affected differentially the drag forces experienced by planktic
colonies; such features were probably adaptations to enhance the depth stability of graptolite
colonies.

CONCLUSIONS

The graptolite nematularium, by virtue of its distance from the thecae and its anatomical association
with the nema, offers unique insights into the method of graptolite peridermal secretion. Data on the
suite of peridermal fabrics and their geometry match the predictions of the pterobranch model, while
conflicting sharply with the predictions of the extrathecal tissue model. Thus, we advocate the
acceptance of the pterobranch model and the rejection of the extrathecal tissue model as a general
explanation for the secretion of graptolite periderm.

This corroboration of the pterobranch model has important implications for our understanding of
graptolite palaeobiology and evolution. Through their work on pterobranch and graptolite
peridermal ultrastructure, Towe and Urbanek (1972), Urbanek and Towe (1974, 1975), and
Urbanek (1976, 1978) have stimulated a great deal of interest in and debate about the nature of the
graptolite zooid and its phylogenetic relationship to pterobranchs. Urbanek ( 1976, 1978) suggested
that the many structural and constructional similarities between coenecia of pterobranchs and
graptolite rhabdosomes, as well as the inferred anatomical similarities, are all analogous homoplasies,
and so indicate no close relationship between these groups. This view has become progressively less
tenable as additional information about graptolite and pterobranch periderm has accumulated.
Armstrong et al. (1984), in contrast to suggestions by Dilly (1971 ), showed that the fibrillar material
comprising the bulk of the periderm in both groups is probably collagen. Andres (1980) has shown
that the very different density of the fibrillar fabrics employed by pterobranchs and graptoloids is
bridged among the benthic graptolites, such as the crustoids and tuboids. Hutt’s (1974) work on the
early growth stages of A. hunnebergensis and Clonograptus tenellus and our work on the P.
scharenbergi nematularium demonstrate that the nema and associated structures are probably

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PALAEONTOLOGY, VOLUME 29

homologous with the pterobranch pectocaulus and that the mode of peridermal formation is wholly
similar in the two groups. Thus, this work reaffirms the close phylogenetic relationship between the
Graptolithina and the Pterobranchia that Kozlowski (1949, 1966) forcefully developed and that
Crowther (1981) and others have recently stressed.

Our model of nematularium formation has additional implications for graptolite palaeobiology.
The frequent and independent evolution of nematularia among nematophorous graptolites indicates
that these structures served an important function in the ecology of these species. This function
apparently was to enhance depth stability through their disproportionate contribution to the
colony’s drag. The depth stratification model of graptolite ecology supported by Erdtmann (1976)
and Kaljo (1978), among others, now appears more likely to be a useful model. The maintenance of a
preferred depth through drag (perhaps, but not necessarily, in combination with lophophore-
generated currents) may have been a pervasive factor in graptolite evolution. Further study of
graptolite structure and palaeoecology employing these concepts will probably provide data essential
to our understanding of the major features of graptolite evolutionary history.

Acknowledgements. We conducted much of the research embodied in this paper while graduate students
at Harvard University. We thank Drs Stephen Jay Gould and Robert M. Woollacott (Museum of
Comparative Zoology, Harvard University) for their support of this project. Ronald Eng and Felicita
d’Escrivan also provided valuable assistance in the preparation of a number of the scanning electron
micrographs.

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dilly, p. n. 1971 . Keratin-like fibers in the hemichordate Rhabdopleura compacta. Z. Zellforsch. mikrosk. Anat.
117, 502-515.

MITCHELL AND CARLE: SECRETION OF GR APTOLITE NEMATULARIUM

389

erdtmann, b.-d. 1976. Ecostratigraphy of Ordovician graptoloids. In bassett, m. g. (ed.). The Ordovician
System. Pp. 621-643. Proc. Paleont. Symp. Birmingham, 1974, Univ. Wales Press, Nat. Mus. Wales,
Cardiff.

finney, s. c. 1979. Mode of life of planktonic graptolites: flotation structure in Ordovician Dicellograptus sp.
Paleobiol. 5,31 39.

gould, s. j. and katz, m. 1975. Disruption of ideal geometry in the growth of receptaculitids: a natural
experiment in theoretical morphology. Ibid. 1, 1-20.

hutt, J. 1974. The development of Clonograptus tenellus and Adelograptus hunnebergensis. Lethaia , 7, 79-92.
hyman, L. H. 1959 The Invertebrates , Vol. V , The smaller coelomate groups, 609 pp. MacGraw Hill, New York.
jackson, d. e. 1974. Tremadoc graptolites from Yukon Territory, Canada. Spec. Pap. Palaeont. 13, 35-
58, pi. 5.

jones, w. d. v. and rickards, r. b. 1967. Diplograptus penna Hopkinson, 1869, and its bearing on vesicular
structures. Palaeont. Z. 41, 173-185.

kaljo, d. l. 1978. On the bathymetric distribution of graptolites. Acta palaeont. pol. 23, 523-531.
kirk, n. h. 1969. Some thoughts on the ecology, mode of life and evolution of the Graptolithina. Proc. geol.
Soc. Lond. 1959, 273-292.

— 1972. Some thoughts on the construction of the rhabdosome in the Graptolithina, with special reference to
extrathecal tissue and its bearing on the theory of automobility. Univ. Coll. Wales , Aberystwyth , Dept. Geol.
Pub!. 1, 1-21, pis. I -5.

— 1979. Thoughts on coloniality in the Graptolithina. In larwood, c. and rosen, b. r. (eds.). Biology and
systematics of colonial organisms , 411-432. Academic Press, London and New York.

kozlowski, r. 1938. Informations preliminares sur les Graptolithes du Tremadoc de la Pologne et sur leur
portee theorique. Annls Mus. zool. pol. 13, 183-196.

— 1949. Les Graptolithes et quelques nouveaux groups d’animaux du Tremadoc de la Pologne. Palaeont. pol.
3, i-xii, 1-235, pis. 1-42.

1966. On the structure and relationships of graptolites. J. Paleont. 40, 489-501.

— 1971. Early development stages and the mode of life of graptolites. Acta palaeont. pol. 16, 313-343,
pis. 1-3.

lenz, a. c. 1974. A membrane-bearing Cyrtograptus, and an interpretation of the hydrodynamics of
cyrtograptids. Spec. Pap. Palaeont. 13, 205-214.

muller, a. h. and schauer, M. 1969. Uber schwebeenrichtungen bei Diplograptidae (Graptolithina) aus dem
Silur. Freiberger ForschHft , C245, 5-26.

rickards, R. b. 1975. Palaeoecology of the Graptolithina, an extinct class of the phylum Hemichordata. Biol.
Rev. 50, 397-436.

— and crowther, p. r. 1978. New observations on the mode of life, evolution and ultrastructure of
graptolites. In larwood, c. and rosen, b. r. (eds.). Biology and systematics of colonial organisms , 397-410.
Academic Press, London and New York.

riva, j. 1974. Late Ordovician spinose climacograptids from the Pacific and Atlantic faunal provinces. Spec.
Pap. Palaeont. 13, 107-126, pis. 19 and 20.

ruedemann, r. 1904. Graptolites of New York, Pt. I. Graptolites of the lower beds. Mem. N.Y. St. Mus. nat.
Hist. 7, 455-803, pis. 1-17.

— 1908. Graptolites of New York, Pt. II, Graptolites of the higher beds. Ibid. 11, 1 583, pis. 1 -31 .
schepotieff, A. 1906. Die Pterobranchier. Anatomische und histologische Untersuchungen fiber Rhabdopleura
normanii Allman und Cephalodiscus dodecaloplius M’lnt. I Tiel. Rhabdopleura normanii Allman. 1. Die
Anatomie von Rhabdopleura. Zool. Jb. Abt. Anat. 23, 463-534, pis. 25-33.

— 1 907. Die Pterobranchier. Anatomische und histologische Untersuchungen fiber Rhabdopleura normanii
Allman und Cephalodiscus dodecaloplius M’lnt. I Tiel. Rhabdopleura normanii Allman. 2. Knospungsprozess
und Gehause von Rhabdopleura. Ibid. 24, 193-238, pis. 17-23.

seilacher, A. 1970. Arbeitskonzept zur Konstruktionsmorphologie. Lethaia , 3, 393-396.
shapiro, a. h. 1961. Shape and flow: the fluid dynamics of drag, 186 pp. Doubleday, Garden City, New York.
Thompson, d. w. 1948. On growth and form (2nd edn.), 1,116 pp. Cambridge University Press, Cambridge.
towe, k. m. and urbanek, a. 1972. Collagen-like structures in Ordovician graptolite periderm. Nature , Lond.
237, 443-445.

urbanek, a. 1963. On generation and regeneration of cladia in some Upper Silurian monograptids. Acta
palaeont. pol. 8, 135-254.

1976. The problem of graptolite affinities in the light of ultrastructural studies on peridermal derivatives in
pterobranchs. Ibid. 21, 3-36, pis. I 7.

390

PALAEONTOLOGY, VOLUME 29

urbanek, a. 1978. Significance of ultrastructural studies for graptolite research. Ibid. 23, 595-629, pis. 27-30.
— koren’, t. n. and mierzejewski, p. 1982. The fine structure of the virgular apparatus in Cystograptus
vesiculosus. Lethaia , 15, 207-228.

and towe, k. m. 1974. Ultrastructural studies on graptolites. 1. The periderm and its derivatives in the
Dendroidea and in Mastigograptus. Smithson. Contr. Paleobiol. 20, 1 -48. pis. 1 -30.

1975. Ultrastructural studies on graptolites. 2. The periderm and its derivatives in the graptolites.
Ibid. 22, 1-48. pis. 1-24.

wardlaw, c. w. 1953. A commentary on Turing's diffusion-reaction theory of morphogenesis. New Phytol.
52, 40 47.

wiman, c. 1895. Uber die Graptolithen. Bull. geol. Instn Univ. Upsala , 2, 239-316, pis. 9-15.

CHARLES E. MITCHELL

Department of Geological Sciences
State University of New York at Buffalo
Amherst, New York 14226, USA

KAREN J. CARLE

Typescript received 18 April 1985
Revised typescript received 8 August 1985

Department of Biology
Osborn Memorial Laboratory
Yale University, New Haven
Connecticut 0651 1, USA

ELLISITES, AN UPPER ORDOVICIAN H ELIOLITI D
CORAL INTERMEDIATE BETWEEN COCCOSERIDS

AND PROPORIDS

by OWEN A. DIXON, THOMAS E. BOLTON and PAUL COPPER

Abstract. The Upper Ordovician heliolitid corals Ellisites labechioides gen. et sp. nov. and E. astomata
(Flower) combine vesicular skeletal plates with zones of strongly dilated vertical trabeculae. In these characters
they provide the first evidence of a phylogenetic link between the Coccoseridicae and Proporicae. They are
referred to a new family, the Ellisitidae, and included in the Coccoseridicae, which necessitates taxonomic
modification of the latter to include genera with vesicular skeletal plates. They show features most related to
Coccoseris Eichwald, 1855, and to two of three species considered to have been erroneously referred to the
stromatoporoid Dermatostroma Parks, 1910. Their substantially vesicular skeletal development can lead them
to be mistaken for strongly cystose labechiid stromatoporoids.

Recent publications (e.g. Bogoyavlenskaya and Boyko 1979, p. 31) have explored the relation-
ships, real or apparent, between some heliolitid corals and some stromatoporoids. Nestor (1981)
proposed that the close similarity between the dense trabecular skeleton of protaraeids (Helio-
litoidea) and the fibro lamellar skeleton of lophiostromatids (Stromatoporoidea) was evidence
of common origin. Similarly, he likened the cystose skeletons of proporids (Heliolitoidea) to those
of labechiids (Stromatoporoidea). Stearn (1982) argued generally against these and other such
morphological links. He suggested that the occurrence and stratigraphic distribution of stromato-
poroids supported their evolution as a separate, unitary group, despite the \ . . plethora of linking
forms . . .’ (ibid., p. 515) illustrating morphological continuity between stromatoporoids and several
other groups. The proposed relationship has also been rejected recently by Scrutton (1984, p. 1 14).

A new family of heliolitid corals that provides new information on one of these ‘links’ occurs in
Upper Ordovician rocks on Anticosti Island, Quebec. It is significant for the resemblances it bears
to several taxa of heliolitid corals and stromatoporoids. Its skeletal structures relate it unequivocally
to the heliolitid Coccoseris Eichwald, 1855, and, in turn, to some species formerly referred to the
stromatoporoid Dermatostroma Parks, 1910. Its morphological variability extends to forms appear-
ing deceptively like primitive labechiid stromatoporoids. It also significantly occupies an intermediate
position, not previously recorded (Nestor 1981, pp. 24-25), between heliolitids of substantially vesicu-
lar structure (Proporicae) and those strongly trabecular (Coccoseridicae or Protaraeida).

The few occurrences of fossils now considered to belong to this family are widely spread in North
America, from Texas to eastern and northern Canada. Well-preserved material belonging to two
species, one of them new, has been collected from Anticosti Island (text-fig. 1 ). In particular, specimens
have been found in coral-rich limestones and shales near the top of the Vaureal Formation (Ashgill-
Richmondian; Nowlan and Barnes 1981 ) of western and north-eastern Anticosti Island, in a bioherm
in member 4 of the Ellis Bay Formation (Lake 1981; Ashgill-Gamachian; McCracken and Barnes
1981) of central Anticosti Island, and through the lower two-thirds of the Ellis Bay Formation, north-
eastern Anticosti Island (text-fig. 2). The objectives of this paper, therefore, are to describe these
taxa and to evaluate both their systematic relationships as a new group of heliolitid corals, and their
deceptive mimicry of labechiid stromatoporoids.

Further information on the bio- and lithostratigraphic setting of these corals can be found in Bolton
(1972, 1981 ) and Petryk (1979, 1981).

[Palaeontology, Vol. 29, Part 2, 1986, pp. 391-413, pis. 30-34.|

392

PALAEONTOLOGY, VOLUME 29

O n^895,8(C) ISOMERSET
l^W\ ^j)V89513 (A)/ ISLAND

(^C\'S^§986P(C> 1 MELVILLE
Y\f 189865(A)] PENINSULA

84617, 85487

SOUTHAMPTON^0 r— s_. . a,

ISLAND (A) \ \ AKPATOK

I \ ^-ISLAND

| 12.5303 (A) \ (A)

I *25275,25281, 25283 (A)

81821 (A,C)*

MILES

text-fig. 1. Map of North American occurrences of Ellisites gen. nov. Five-digit numbers denote Geological
Survey of Canada (GSC) locality numbers. For Iocs. 1 1 6 in the upper Ordovician Vaureal and Ellis Bay forma-
tions of Anticosti Island, see Appendix.

SYSTEMATIC PALAEONTOLOGY

The repositories of the specimens quoted are denoted by the following abbreviations: GSC, Geological Survey
of Canada, Ottawa; IU, Paleontology Collections, Indiana University, Bloomington; ROM, Royal Ontario
Museum, Toronto; UM, Museum of Paleontology, University of Michigan, Ann Arbor; NMBM, New
Mexico Bureau of Mines, Socorro.

Order heliolitida Freeh, 1897
Suborder heliolitina Freeh, 1897
Superfamily coccoseridicae Kiaer, 1899

Diagnosis (emended after Hill 1981). Corallum encrusting, laminar or subglobular; longitudinal
skeletal elements commonly greatly thickened and porous or aporose; horizontal skeletal elements
thin and abundant to absent; tabularia with twelve contiguous septa composed of monacanths? (or
rhabdacanths) directed upward adaxially; in some, septa long, thick, filling lurnina; in some, septa
short with flat tabulae present; in some, septa ill-defined, with vertical septal and axial trabeculae
filling or partly filling lurnina; coenenchyme of longitudinal trabeculae commonly so thick that no
tubular lurnina occur; in some, trabeculae outline tubules that may be crossed by subhorizontal
diaphragms; in some, thick trabeculae combined with vesicular plates in coenenchyme and tabularia.

Family ellisitidae fam. nov.

Diagnosis. Corallum incorporating vesicular transverse skeletal elements and aporose, pinnately
fibrous, longitudinal skeletal elements.

Occurrence. Ashgill (Edenian to Gamachian) of North America.

DIXON, ET AL.\ UPPER ORDOVICIAN HELIOLITID CORAL

393

WESTERN VAUREAL EASTERN

text-fig. 2. Stratigraphic setting of Anticosti Island collecting localities
for Ellisites gen. nov. Western Anticosti and Vaureal River sections after
McCracken and Barnes (1981, p. 62). Eastern Anticosti section based on
unpublished data of P. Copper, from the Schmitt Creek-Mill Bay area
(Vaureal Formation) and Table Head-Fox Point-Prinsta Bay area (Ellis
Bay Formation). Limestones predominate in blank parts of the sections.

Genus ellisites gen. nov.

Name. From the Ellis Bay Formation, in which it occurs abundantly.

Diagnosis. Coenenchymal, septal, and axial trabeculae weakly differentiated, all vertical; tabularia
outlined by rings of slightly larger trabeculae and filled by axial and septal trabeculae in zones of
trabecular dilation; tabularia largely undefined in non-trabecular zones, may be represented by
columns of incomplete tabulae merging with coenenchymal vesicles.

Contained species. Type species: E. labechioides sp. nov. from the Upper Ordovician (Ashgill) Vaureal and
Ellis Bay formations of Anticosti Island and possibly Stony Mountain Formation, southern Manitoba (this
paper).

E. astomata (Flower, 1961) from the Upper Ordovician of Anticosti Island, Akpatok Island, Bray Island,
north-eastern and southern Manitoba (this paper), and western Texas.

E. glyptum (Parks, 1910) from the Upper Ordovician (Ashgill) of south-western Ohio, north-eastern
Manitoba, Melville Peninsula, and Somerset Island.

Ellisites labechioides sp. nov.

Plate 30; Plate 31, figs. 1-3, 5 and 6; Plate 32, figs. 1 and 2; text-fig. 3a
v 1981 Labechia n. sp. aff. L. mirabilis-L. banksi group; Bolton, p. 42, pi. 1, fig. 4; pi. 2, figs. 1 and 2.

394

PALAEONTOLOGY, VOLUME 29

Derivation of name. Labechioides refers to the morphological likeness to labechiid stromatoporoids.

Type locality and horizon. Loc. 1 1: coastal tidal flat exposure (exposed at low tide) and bluffs to the west of
Lousy Cove, north to Table Head, north-eastern Anticosti Island. Ellis Bay Formation: biostrome 0-5 m
thick, enclosed by calcareous shale, situated 24-5-26 0 m below the Ellis Bay/Becscie formational boundary
as defined by Cocks and Copper (1981).

Material , horizons , and localities. Holotype, nineteen paratypes, and numerous other specimens from Anticosti
Island. Holotype, GSC 77880 (loc. 1 1), from Ellis Bay Formation. Paratypes from upper Vaureal Formation
include: GSC 67013 and 77892 (loc. 3a), 67022 (loc. 3b), 77893 (loc. 3c), 67023 (loc. 4), and 77894 and 77895
(loc. 5). Paratypes from Ellis Bay Formation include: GSC 77881 (loc. 9), 77882 (loc. 10), 77883 (loc. 11),
77884 (loc. 15), and 67016, 77885-77891 (loc. 16). Other specimens from Iocs. 12, 13, and 14. Hypotype,
GSC 77917, from Penitentiary Member, Stony Mountain Formation, Stony Mountain, southern Manitoba.
Upper Ordovician (Richmondian-Gamachian).

Diagnosis. Ellisites with strongly vesicular coenenchyme and thin zones of short dilated trabeculae;
trabeculae prismatic, 0-25 -0-40 mm in diameter, composed of fibres diverging upward at 20-30°
from vertical. Vesicles moderately convex, with width : height ratios of 2-4 : 1 to 2-8 : 1 . Corallites
weakly defined, 1 -5- 1 -7 mm in diameter, with centres 1 -8-2-2 mm apart.

Description. Most specimens from western and central Anticosti Island are laminar sheets with flat, broad
domal, or cylindrical forms mimicking surfaces encrusted, some even irregularly nodose. Corallum thicknesses
generally vary from 1-0-5 0 cm, and the largest specimen is 9-0 cm across, except at locality 4 where specimens
up to 28-0 cm in diameter and 8-5 cm high have been collected from Vaureal Formation bioherms. The Ellis
Bay Formation specimens from the north-east coast are mainly domal to rounded colonies, 15-0-20-0 cm in
diameter and 1 0-0 1 5-0 cm high (maximum 24-0 cm diameter by 20-5 cm height). Each corallum has a thin
basal epitheca less than 0- 1 mm thick that parallels the substrate in minute detail (PI. 30, fig. 1 ). The remainder
of the corallum consists of two basic skeletal structures in different proportions in different growth zones:
arched vesicles and vertical pillar-like trabeculae.

Vesicles generally predominate in the skeleton, particularly in juvenile parts (PI. 30, fig. 1; PI. 31, figs. 1 and
2). They are moderately convex with average width : height ratios generally between 2-4 : 1 and 2-8 : 1. Vesicle
size varies considerably and this is particularly expressed in alternating growth zones (PI. 30, fig. 6; Bolton
1981, pi. 1, fig. 4). ‘Light’ zones have average values for vesicle width : height (apparent dimensions, as
measured in vertical section) between 0-5 : 0-2 mm and 0-75 : 0-35 mm in different specimens. The largest
vesicles are up to 2-0 mm wide and 0-6 mm high and tend to occur toward the base of the corallum. Generally
thinner ‘dark’ zones have vesicles one-half to one-third the size of those in the ‘light’ zones — width : height
averages between 0-25 : 0- 1 mm and 0-3 : 0-1 mm in different specimens. Convexity does not change consistently
from one zone to another; more variation can be seen from one specimen to another than from zone to zone.

Short vertical trabecular rods are concentrated in ‘dark’ zones in juvenile parts of coralla and are usually
more frequent and more pervasive in later growth stages (PI. 30, figs. 1 and 4). They form thin layers 0-2-0-5
mm thick in which they are expanded laterally and commonly are in contact with adjacent trabeculae along
part of their length. Their margins remain sharp and clear, and resulting polygonal prisms (PI. 30, fig. 5;
PI. 31, fig. 3) average about 0-3 mm (range 0-25 0-4 mm) in diameter. The trabeculae consist of pinnately

EXPLANATION OF PLATE 30

Figs. 1-6. Ellisites labechioides gen. et sp. nov. from Anticosti Island. 1, paratype, GSC 77885, loc. 16, Ellis
Bay Formation, member 4; longitudinal section showing encrusting basal epitheca, and astogenetic change
from mainly vesicular (below) to mainly trabecular (above); upper surface extensively bored, x 5. 2,
paratype, GSC 77882, loc. 10, Ellis Bay Formation; exterior surface with sediment-filled calices surrounded
by rings of papillae (ends of trabeculae), x 9. 3, paratype, GSC 67023, loc. 4, upper Vaureal

Formation; longitudinal section showing column of broader vesicles (tabulae) bordered by smaller vesicles
(coenenchyme), x 10. 4, paratype, GSC 77887, loc. 16, Ellis Bay Formation, member 4; longitudinal
section showing characteristic V-shaped arrangement of fibres in trabeculae, x 10. 5, 6, holotype, GSC
77880, loc. 11, Ellis Bay Formation; tangential section (5) showing zone of fully dilated prismatic trabeculae
(upper right) between zones mainly of vesicular plates, and longitudinal section (6) with zones of smaller
vesicles and isolated trabeculae alternating with zones of larger vesicles mostly free of trabeculae, both x 10.

PLATE 30

DIXON, BOLTON and COPPER, Ellisites

396

PALAEONTOLOGY, VOLUME 29

arranged calcite fibres diverging upward at 20-30° from the axes of trabeculae (PI. 30, fig. 4; PI. 31, fig. 5). In
later parts of the corallum where trabecular zones are more crowded, some trabeculae continue from one
zone to the next and reach lengths up to 3-5 mm. Trabeculae have acute to rounded terminations at the top,
and longer ones pinch and swell in penetrating 'light' and 'dark’ zones respectively, but the lateral extensions
do not coincide with associated vesicle margins as in the swelling pillars of Labechia (e.g. L. venusta Yavorsky,
1955 in Nestor 1966, pi. 2, tig. 1). A few short isolated trabeculae occur in 'light’ zones and in some specimens
trabeculae are so weakly developed in ‘dark’ zones that they remain as isolated short spindle-shaped or
longer tapering rods concentrated at particular levels (PI. 31, figs. 2 and 6). Growth of trabeculae was generally
initiated on arched upper surfaces of vesicles (PI. 31, fig. 5). Some are shorter than the vaulted spaces beneath
vesicles; others penetrate one or more vesicles vertically. Both penetration of vesicles by trabeculae and,
conversely, interruption of vertically aligned trabeculae by complete vesicles are common. The latter, however,
is probably only apparent and can result commonly from the plane of section being parallel to, but slightly
offset from, the axes of trabeculae that pinch and swell along their length.

The coenosteum contains corallites that are most clearly shown by calices on the exteriors of several
specimens (PI. 30, fig. 2; PI. 32, fig. 1) but can rarely be discerned in transverse sections of most specimens.
Where sections are cut tangential to the upper surfaces of zones of dilated trabeculae, corallite walls are
defined by regularly disposed rings of contiguous trabeculae surrounding clusters of axial trabeculae that
appear smaller and separated because they are intersected nearer their narrow terminations (text-fig. 3a). Each
ring comprises thirteen to sixteen trabeculae, some slightly elongate radially; the latter are suggestive

text-fig. 3. a, Ellisites labechioides gen. et sp. nov.; paratype, GSC
77894, from upper Vaureal Formation, loc. 5, Anticosti Island. Tracing
of tangential section near upper surface of trabecular zone. Corallites
shown by clusters of isolated smaller (axial) trabeculae surrounded by
larger (septal, coenenchymal) trabeculae. See also Plate 31, fig. 3. b,
E. astomata (Flower); hypotype, GSC 77900, from upper Vaureal
Formation, loc. 3c, Anticosti Island. Tracing of tangential section
showing clusters of smaller trabeculae in corallite centres, surrounded
by larger trabeculae. See also Plate 34, fig. 1. Scale bars 1 0 mm.

EXPLANATION OF PLATE 31

Figs. 1-3, 5, 6. Ellisites labechioides gen. et sp. nov. from Anticosti Island. 1, 2, paratype GSC 77886, loc. 16,
Ellis Bay Formation, member 4; tangential (1) and longitudinal (2) sections through zones mainly of
vesicular plates, with a thin zone of small vesicles with isolated trabeculae in fig. 2, x 10. 3, paratype GSC
77894, loc. 5, upper Vaureal Formation; tangential section, x 10 (compare with text-fig. 3). 5, paratype,
GSC 77889, loc. 16, Ellis Bay Formation, member 4; longitudinal section showing trabeculae initiated on
upper surfaces of vesicles and penetrating subsequent vesicles, x 20. 6, paratype, GSC 77888, loc. 16, Ellis
Bay Formation, member 4; tangential section showing a zone of isolated rounded trabeculae and a non-
trabeculate vesicular zone, x 10.

Fig. 4. Coccoserid Dnalitesl speleana (Hill). GSC 77918, Fossil Hill, west of Mandurama, New South Wales,
Kalimna Limestone Member of Fossil Hill Limestone; longitudinal section showing upwardly converging
septal trabeculae, x 10.

PLATE 31

DIXON, BOLTON and COPPER, Ellisites

398

PALAEONTOLOGY, VOLUME 29

of septal trabeculae but the twelvefold septal pattern typical of heliolitids is at best obscure. In longitudinal
section there is no clear indication of inclined trabeculae that might represent septa.

Corallites average 1-5— 1 -7 mm in diameter (outside the ring of trabeculae) and have calices about 1-2-1 -4
mm in diameter. Their centres are spaced 1 -8—2-2 mm apart, corresponding to numbers of corallites ranging
from eighteen to thirty-six per cm2 in cross-section. Corallites are indistinguishable in zones of full dilation of
trabeculae: a uniform array of polygonal prisms belies the presence of corallites and of coenenchymal, septal,
and axial trabeculae. Corallites are, at most, vaguely expressed in vesicular zones. Longitudinal sections of
some specimens show slight but repeated depressions in the layers of vesicles. Beneath these depressions are
indistinctly bounded columns of slightly larger vesicles incorporating marginal ones that dip gently into the
depression and inosculate with axial vesicles that are horizontally based. In several specimens (e.g. PI. 30, fig.
3; PI. 32, fig. 2), where these minor depressions are not expressed, smaller and larger vesicles are very weakly
segregated into columns, with larger vesicles in columns of a size and spacing comparable to corallite size and
spacing in trabecular zones. If these columns of larger vesicles represent corallites, then the vesicular
incomplete tabulae represented are usually scarcely distinguishable from horizontally based coenenchymal
vesicles.

Discussion. E. labechioides sp. nov. differs from the other species on Anticosti Island, E. astomata ,
in having a predominantly vesicular coenosteum with only thin zones of short trabeculae, and in
having the pinnate trabecular fibres consistently much more narrowly divergent upwards. It differs
for similar reasons from Melville Peninsula specimens referred by Bolton (1977, p. 29, pi. 3) to
Coccoseris astomata Flower. Relationships and similarities are discussed further below. The
southern Manitoba specimen (GSC 77917) varies in that the trabecular fibres are more broadly
divergent, more like E. astomata.

Ellisites astomata (Flower, 1961)

Plate 32, figs. 3-7; Plate 33; Plate 34, fig. 1; text-fig. 3b

1961 Coccoseris astomata Flower, pp. 56-57, pis. 16-18.
v 1975 Coccoseris astomata Flower; Dixon, p. 176 (pars).
v 1975 stromatoporoids, Cumming, p. 38 (pars).
v 1975 Coccoseris cf. C. astomata Flower; Norford in Trettin, p. 49.
v 1976 Coccoseris astomata Flower; Bolton in Workum et al., p. 170, pi. 1, figs. 5 and 6.
v 1977 Coccoseris astomata Flower; Bolton (pars), p. 29, pi. 3, figs. 2, 3, 5; non pi. 3, figs. 1 and 4.

Type locality and horizon. Holotype, NMBM 670, is from near the crest of Scenic Drive, El Paso, Texas.
Second Value Formation, Montoya Group; Edenian -lower Maysvillian.

EXPLANATION OF PLATE 32

Figs. 1 and 2. Ellisites labechioides gen. et sp. nov. Paratype, GSC 77895, loc. 5, Anticosti Island, upper
Vaureal Formation. 1, exterior surface showing corallite calices, x 5. 2, longitudinal section through
mostly vesicular coenosteum with very thin zones of trabeculae and smaller vesicles; vesicles are in vaguely
defined columns, with larger ones (apparently tabulae in corallites) segregated from somewhat smaller ones
(dissepiments in coenenchyme, appearing slightly darker on photograph), x 5.

Figs. 3-7. E. astomata (Flower) from Anticosti Island, upper Vaureal Formation. 3, 4, hypotype, GSC
77901, loc. 5, longitudinal section (3) showing growth interruptions: trabeculae to right terminate beneath
a thin zone of fibro-normal calcite that forms a base for succeeding vesicular plates while trabeculae to left
continue across horizon of interrupted growth, x 10; exterior surface (4) showing corallite calices as clusters
of smaller papillae (axial trabeculae) in slight depressions, surrounded by larger papillae (?septal and
coenenchymal trabeculae), x 5. 5, 7, hypotype, GSC 77902, loc. 5; tangential section (5) of a thin zone of
trabeculae showing their initiation on vesicular plates (below), expansion to contiguity (centre), and acute
terminations (top left), x 10; longitudinal section (7) of alternating vesicular and thin trabecular zones in
the lower part of a colony, and the base of an overlying entirely trabecular zone, x 10. 6, hypotype, GSC
77899, loc. 3c; longitudinal section of specimen with nodular growth surfaces and marked growth zonation;
nodes are underlain by pillars of continuous trabecular construction while intervening depressions show
alternating thin trabecular layers and thicker lenses of vesicular plates, x 4.

PLATE 32

DIXON, BOLTON and COPPER, Ellisites

400

PALAEONTOLOGY, VOLUME 29

Material , horizons, and localities. Nine hypotypes and other specimens from the Upper Ordovician
(Richmondian) upper Vaureal Formation of Anticosti Island: GSC 77896 (loc. 1), 77897 (loc. 2 = GSC loc.
36269), 77898 (loc. 3a = GSC loc. 36146), 77899 and 77900 (loc. 3c = GSC loc. 76087), 77901 and 77902
(loc. 5), 77903 (loc. 6), and 77904 (loc. 8). Other specimens from loc. 7. Fifteen hypotypes from other
localities: Upper Ordovician (Edenian) Bad Cache Rapids Formation, Melville Peninsula, GSC 42920 and
42921 (GSC loc. 89865); Upper Ordovician (Edenian) Baillarge/Bad Cache Rapids Formation, Bray Island,
GSC 78027 (GSC loc. C-2845); Upper Ordovician (Edenian) beds, Akpatok Island, GSC 41177; Upper
Ordovician (Edenian Maysvillian) Thumb Mountain Formation, Somerset Island, GSC 77905 (GSC loc.
89513); Upper Ordovician (Edenian Maysvillian) Bad Cache Rapids Group— Portage Chute Formation,
Churchill River, GSC 77919 (GSC loc. 25275); Upper Ordovician (Richmondian) Churchill River Group —
Caution Creek Formation, South Knife River, GSC 77907 (GSC loc. 25303) and mouth of Chasm Creek,
GSC 77908 (GSC loc. 25281), Chasm Creek Formation, member 1, mouth of Chasm Creek, GSC 77909-
7791 1 (GSC loc. 25281), and Churchill River, GSC 77912 (GSC loc. 25283), and Angling River, GSC 77906
(GSC loc. 81821), north-eastern Manitoba; Upper Ordovician (Edenian) Bad Cache Rapids Group, 0-6 km
west of Coral Harbour, Southampton Island, GSC 77913, and 77914 (GSC Iocs. 84617 and 85487).

Diagnosis. Ellisites with thick zones of fully dilated trabeculae and subordinate sectors of vesicular
coenosteum or, rarely, with vesicles obscure; trabeculae prismatic, 0-2-045 mm in diameter,
composed of fibres diverging upward at 50-60° from vertical, vesicles moderately convex, with
width : height ratios of 21 : 1 to 2-5 : 1; corallites obscure, 1-5—1 -9 mm in diameter, with centres
1-6-2-3 mm apart.

Description. Five of the Anticosti Island hypotypes are parts of lamellar sheets up to 3-5 cm thick and 10 0 cm
wide, and a sixth and seventh are upwardly expanding domal forms up to 4-5 cm high and 8 0 cm across. A
thin basal epitheca defines the base of the colony and is intimately moulded to the surface of the encrusted
substrate. The remainder of the corallum is constructed of arched vesicles and strongly dilated vertical
trabeculae in fairly discrete growth zones.

A vesicular zone typically follows the basal epitheca and other vesicular sectors occur in trabecular zones
higher in the colony (PI. 32, figs. 3 and 6). Vesicles are moderately convex with average width : height ratios
between 2-1:1 and 2-5 : 1. Average width : height values (apparent values, as measured in longitudinal section)
range from 0-55 : 0-25 mm to 0-75 : 0-3 mm in different specimens. Vesicles attain maximum widths of 1-5 mm
and heights of 0-9 mm, usually in the basal zone of a corallum. Vesicular zones tend to be discontinuous
laterally, mainly forming lens- or wedge-shaped sectors that fill substrate and colony surface irregularities
(PI. 32, figs. 3 and 6). Vesicles are obscure in some specimens and were not recorded in the holotype (Flower
1961, pp. 56-57).

Zones of strongly dilated vertical trabeculae up to 15 mm thick form the bulk of the corallum in these
specimens. The trabeculae either arise as discrete pillars directly from the surface of a layer of vesicles (PI. 33,
fig. 5) or are rooted in an initial thin layer of fibro-normal calcite covering a layer of vesicles (PI. 32, fig. 3;
PI. 33, fig. 6). The trabeculae typically expand abruptly to contiguity with adjacent trabeculae (PI. 32, fig. 7;
PI. 33, fig. 5) and remain fully dilated for most of their length. In the main trabecular zones they form sub-
parallel, vertical, polygonal prisms only locally interrupted by vesicular plates in discontinuous layers one
or a few vesicles thick (PI. 32, fig. 3). The prisms average 0-3-0-35 mm in diameter (range 0-2-0-45 mm), and

EXPLANATION OF PLATE 33

Figs. 1-6. Ellisites astomata (Flower). 1, hypotype, GSC 77913, GSC loc. 84617, Southampton Island, Bad
Cache Rapids Formation; tangential section showing mostly contiguous prismatic trabeculae with well-
preserved fibrous microstructure, x 10. 2, 3, hypotype, GSC 77914, GSC loc. 85487, Southampton Island,
Bad Cache Rapids Formation; longitudinal (2) and tangential (3) sections showing fully dilated prismatic
trabeculae with fibrous microstructure (note diagenetic loss of some microstructure in fig. 3, compared to
fig. 1), x 10. 4, hypotype, GSC 77904, loc. 8, Anticosti Island, upper Vaureal Formation; tangential
section with prismatic trabecular skeleton (lower area) and vesicular sector penetrated by isolated rounded
papillae (ends of trabeculae), x 20. 5, 6, hypotype, GSC 77906, GSC loc. 81821, Angling River, north-
eastern Manitoba, Chasm Creek Formation; longitudinal sections showing sectors of vesicular plates
interrupting prismatic trabeculae (5), x 10; and a sector of vesicular plates penetrated by papillate ends of
trabeculae in the same corallum (6), x 20.

PLATE 33

DIXON, BOLTON and COPPER, Ellisites

402

PALAEONTOLOGY, VOLUME 29

terminate as acute papillae at the top (PI. 32, tig. 6; PI. 33, figs. 4 and 5). They consist of pinnately arranged
calcite fibres diverging upward at angles of 50-60° from the axes of trabeculae (PI. 33, figs. 2 and 5). Both V
and U-shaped arrangements of fibres are evident in longitudinal sections; the former is shown where trabeculae
are cut along their axes, the latter in trabeculae cut parallel to their axes but off-centre.

Short conical denticle-like structures are scattered through vesicular sectors (PI. 32, figs. 5 and 7), a few
rising from the surface of any one vesicle and not reaching the vesicle above. Similar short denticles arise
from thin fibro-normal layers resting locally directly on the basal epitheca. These denticles appear to represent
trabeculae that were 'aborted' without developing into zones of fully dilated prisms. Some of these short
denticles show the distinctive trabecular pinnate fibrous structure, while others are composed of dark granular
calcite. The differences are attributed to recrystallization, as similar variations can be seen both within the
thin layers of fibro-normal calcite and from one trabecular prism to another in the principal layers (PI. 32,
fig. 3; PI. 33, figs. 2 and 3); all are interpreted as originally of fibrous structure.

The presence of corallites can be detected with certainty as calices on the upper surfaces of several specimens
(e.g. PI. 32, fig. 4). Corallites appear to be differentiated clearly only at the upper surfaces of layers of
trabecular prisms where the trabeculae terminate in small acute papillae. The latter are readily reduced by
abrasion to tubercle-like form and calice walls become defined by rings of larger tubercles enclosing slightly
depressed axial clusters of smaller ones (PI. 32, fig. 4). None of the tubercles in a ring is distinctly elongate
radially, analogous to radial elongation of septal trabeculae in some other coccoserids. In two specimens
corallite diameters are 1 -5 and T9 mm, calice diameters 1 T and 1 -5 mm, and corallite centres average 1 -6 and
2-3 mm apart.

In transverse section the trabecular prisms appear as a mosaic of sharply delimited polygons with little
suggestion of corallite structure (PI. 33, figs. 1 and 3). One specimen from Anticosti Island (text-fig. 3b) shows
numerous clusters of six to twelve generally smaller trabeculae (~0-2 mm diameter) surrounded by larger
ones ( ~ 0-35 mm diameter). The clusters are ill-defined but their centres average about T9 mm apart (based
on seventy measurements), i.e. distances of the same order as the spacing of corallites on other specimens.
Another specimen from Akpatok Island (PI. 34, fig. 1) is similar. No other indication of corallite structure
has been recognized in transverse sections.

In longitudinal section the trabecular prisms are uniformly vertical with no indication of inclination such
as seen in septal trabeculae of many coccoserids. No trace of corallite structure is evident in sectors of
vesicular plates.

Discussion. This species differs from E. labechioides sp. nov. in having a coenosteum composed
predominantly of thick zones of contiguous vertical trabeculae, vesicular plates mostly in
discontinuous sectors, and trabeculae with pinnate fibres consistently more broadly divergent
upward.

Flower (1961, pp. 56-57) considered his holotype of C. astomata from the late Edenian-early
Maysvilhan Second Value Formation of western Texas to be anomalous (for a heliolitid coral) in
showing no clear evidence of corallites, merely slight and obscure variations in size and aspect of
the trabeculae. Corallites are certainly obscure in E. astomata but are evident as calices on some
well-preserved surfaces of specimens from Anticosti Island (PI. 32, fig. 4), north-eastern Manitoba,
and Southampton Island, and are suggested internally on three specimens by ill-defined but
appropriately spaced clusters of small trabeculae enclosed by slightly larger ones (PI. 34, fig. 1;
text-fig. 3b).

Flower’s holotype compares closely with all the material ascribed to E. astomata in this paper,
except in one character. Vesicular plates are not mentioned in Flower’s description, nor are any
evident in the excellent accompanying photographs (ibid., pis. 16-18) of the well-preserved
specimen. However, the Canadian specimens studied vary in this regard. Many from Anticosti
Island have conspicuous vesicular sectors; others from there and elsewhere (see below) have only
minor or obscure vesicles. The repetition of vesicular sectors is evidently astogenetic and probably
reflects environmentally induced growth variations. The holotype is interpreted, therefore, to be an
anomalous representative of a species that occurs widely in North America but that usually
possesses some vesicular skeletal plates.

An encrusting form (GSC 41 177) assigned to C. astomata from the Edenian beds of Akpatok
Island, with trabeculae 0-20-0-24 mm (range 0-1 4-0-44 mm) in diameter, displays minute basal
vesicles; a similarity to Dermatostromal escanabaense was noted (Bolton in Workum et al. 1976,

DIXON, ET AL.\ UPPER ORDOVICIAN HELIOLITID CORAL

403

p. 170, pi. 1, fig. 6). The specimen is here included in E. astomata. Bolton (1977, p. 29, pi. 3, figs. 1 -

5) referred fossils from the lower Upper Ordovician (Edenian) Bad Cache Rapids Formation of
Melville Peninsula to C. astomata. These specimens too have prismatic trabeculae with broadly
divergent fibres characteristic of Flower’s species. Significantly, they also have local basal sectors
of vesicular plates (‘. . . suggesting a stromatoporoid affinity for the species’— Bolton 1977, p. 29)
as in the Anticosti Island specimens of E. astomata. Among the Melville Peninsula specimens, two
hypotypes (GSC 42920, 42921) have smaller trabeculae (diameters of 0-25-0-45 mm) than the third
(diameters of 0-75-0-9 mm). In the context of the Anticosti Island material the former closely
resemble E. astomata ; the latter is not represented. A domal colony (GSC 78027) from the Edenian
Baillarge/Bad Cache Rapids Formation of Bray Island, Foxe Basin (Trettin 1975, p. 49) has
trabeculae 0-24-0-4 mm in diameter and in the sections prepared has no clearly developed vesicles.
It is assigned to E. astomata and is one of the specimens showing clusters of small trabeculae
(presumably within corallites) surrounded by slightly larger ones. One specimen (GSC 77905) listed
as C. astomata by Dixon (1975, p. 1 76) from the Edenian-Maysvillian Thumb Mountain Formation
of Creswell Bay, Somerset Island (GSC loc. 89513) has trabeculae 0-28-0-40 mm in diameter, with
rare basal vesicles, and is consistent with the Anticosti Island forms of E. astomata. Similarly, one
laminar colony (GSC 77906; PI. 33, fig. 5) collected from the Richmondian Chasm Creek Formation,
Churchill River Group, of the Nelson-Angling rivers area, north-eastern Manitoba (Cumming
1975, p. 38; GSC loc. 81821), has trabeculae averaging 0-32 mm (range 0-24 0-48 mm) in diameter
with vesicular areas at various levels identical to the Anticosti Island forms of E. astomata. A thin
laminar colony (GSC 40949), collected from the Maysvillian-Richmondian Mount Kindle
Formation, Mount Kindle, Franklin Mountains, District of Mackenzie (Norford and Macqueen
1975; GSC loc. 69793), has poorly preserved trabeculae ranging from 0-16 to 0-40 mm in diameter
with no vesicular areas, and is questionably referred to E. astomata. Relationships and similarities
are discussed more fully below.

SEDIMENTARY AND PA L AEOEN VI RONM ENT A L ASSOCIATIONS

The best evidence of lithological and palaeoenvironmental setting is from the coastal exposures of
north-eastern Anticosti Island (Iocs. 6-15); most collecting localities inland are isolated bedding
plane exposures or isolated exposures of more resistant biohermal/biostromal limestone that
provide less information on prevailing depositional environments.

Generally colonies are small and scarce in the upper Vaureal Formation. E. labechioides and E.
astomata occur together in the Vaureal Formation in a bioherm (loc. 3c) and in biostromal nodular
lime mudstone (loc. 5) rich in Palaeophyllum, tabulate corals ( Calapoecia , Paleofavosites , Catenipora ,
Propora , and others), and aulacerid stromatoporoids. E. astomata alone has been collected from
other Vaureal Formation bioherms (loc. 1) along with abundant Paleofavosites and common
Palaeophyllum , Calapoecia , and aulacerid stromatoporoids. In the north-eastern exposures it is
commonly associated with very large Paleofavosites colonies in both argillaceous calcarenite (loc.

6) and nodular grey calcareous shale with thin calcarenite interbeds (Iocs. 7 and 8).

Ellisites is most abundant, largest, and best developed in the lower-middle Ellis Bay Formation.
E. labechioides occurs in profusion in the Table Head Creek Prinsta Bay sections of the lower-
middle Ellis Bay Formation (Iocs. 10-13). In one biostrome, tabulate corals (favositids, heliolitids)
and aulacerid stromatoporoids are packed in a calcareous shale matrix and the biostrome is
underlain and overlain by thin-bedded limestone and dark calcareous shale. The species also occurs
in soft calcareous shale (Iocs. 9, 14, 15) along with abundant tabulate corals and aulacerids. In its
highest stratigraphic occurrence it occurs in both a bioherm and its capping shale (loc. 16), together
with abundant large Palaeophyllum , Paleofavosites , stromatoporoids, and common smaller tabulates
( Propora and Catenipora).

The majority of specimens, therefore, occur in argillaceous sediments or in sequences in which
shales predominate (text-fig. 2). The association suggests mainly turbid, low energy, marine shelf
environments with a substantial influx of fine terrigenous elastics. The environments represented

404

PALAEONTOLOGY, VOLUME 29

through the upper Vaureal and lower-middle Ellis Bay formations on eastern Anticosti Island were
shallow enough, however, to be strongly agitated periodically. Terrigenous silt and quartz sand
were introduced and trough cross bedding is conspicuous in sandstone and associated calcarenite
beds within the predominantly argillaceous succession. Some coral and stromatoporoid colonies
show evidence of being rolled or damaged; some recovered partially and resumed growth; some are
incorporated in channel-fill sandstones.

Ellisites is commonly associated with other corals and stromatoporoids and evidently successfully
exploited their skeletons as substrates for support. Roughly estimated, up to 40% of the Ellisites in
the Ellis Bay Formation encrusted aulacerid stromatoporoids, up to 10% encrusted the tabulate
coral Calapoecia , and the remainder grew either directly on sea-floor sediments or on objects that
are no longer attached. They show evidence both of directly encrusting hard substrates and of
expanding laterally over, and intertonguing with, loose sediment.

THE COCCOSERID PROPORID CONNECTION

The three superfamilies of the Suborder Heliolitina Freeh, 1897, have been distinguished largely by
the nature of their coenenchyme (Hill 1981, p. F602). The Helioliticae Lindstrom, 1876, are
characterized by open vertical diaphragmated tubules; the Proporicae Sokolov, 1949, by dissepi-
ment-like plates; and the Coccoseridicae Kiaer, 1899 (— Protaraeida Bondarenko, 1967), by thick
clinogonally fibrous longitudinal trabeculae.

The Anticosti Island corals described here do not fit unequivocally into any one of these groups
as presently recognized. Their coenosteum is, however, most allied to that of the Coccoseridicae in
having longitudinal skeletal elements (monacanthine trabeculae) greatly thickened, both as fully
dilated longitudinal trabeculae in the coenenchyme and as upwardly directed trabeculae completely
filling tabularia. The group differs from previously known Coccoseridicae in combining this
distinctive trabecular structure with substantial zones or sectors of vesicular plates, the latter much
resembling the coenenchyme of Proporicae. The obscurity of corallites in zones of vesicular plates
is, however, a distinct difference from the Proporicae, in which corallites consistently have clearly
defined walls. The group is therefore placed in the Coccoseridicae and considered to include early
heliolitinid corals with characters suggesting a direct relationship between the Coccoseridicae and
Proporicae. It conveniently forms the connection sought by Nestor (1981, pp. 24-25) who
commented that \ . . phylogenetic relationships between the trabecular and cystose heliolitids are
more obscure, as evidence of the existence of transitory forms between Protaraeida and Proporida
is lacking’.

CLOSE RELATIONSHIPS

Related genera

Ellisites appears to be most closely related to forms variously assigned to Coecoseris Eichwald,
1855, or Protaraea Milne- Edwards and Haime, 1851. Whether Coecoseris and Protaraea are
synonymous or are distinct genera has long been argued in the literature. Recently both Bondarenko
(1980) and Sokolov and Tesakov (1984) contributed to the discussion by re-examining lectotype
material of C. ungerni Eichwald and reassessing it in the context of available literature. Bondarenko
recognized Coecoseris as a valid genus; Sokolov and Tesakov concluded that Coecoseris is a junior
synonym of Protaraea. The latter authors contended that Milne-Edwards and Haime’s description
of the Richmondian material defining their new genus Protaraea does not conform to the description
of the designated type species, the Trentonian Poritesl vetustus Hall, 1847. They considered that
the latter belongs either to Esthonia or to a new genus, and that Milne-Edwards and Haime’s
genotypic material more likely belongs, as indicated earlier by Foerste (1909), to Protaraea
richmondensis Foerste, 1909. The problem may not be resolved further without complementary re-
examination of the type material of Hall (1847) and Milne-Edwards and Haime (1851), as suggested
by Hill (1981, p. F622).

DIXON, ET AL.\ UPPER ORDOVICIAN HELIOLITID CORAL

405

As interpreted by Sokolov and Tesakov (1984), Protar aea (= Coccoseris) is characterized by a
skeleton composed entirely of contiguous trabeculae, with corallites distinguishable only as calices
on the surfaces of colonies. The only two species they considered clearly distinguishable differed
from each other in arrangement of septal trabeculae and spacing of corallites: P. ungerni has
vertical septal trabeculae and more widely spaced corallites, and P. richmondensis has inclined
septal trabeculae and more closely spaced corallites. They considered at least eight other named
species to be questionable pending further study. In contrast, Bondarenko (1980) regarded
Coccoseris as a genus with closely spaced corallites and with entirely vertically arranged septal
baculi (trabeculae) differentiated from axial and coenenchymal trabeculae on well-preserved external
surfaces. The only other coccoserid with solely vertically oriented trabeculae was included in a new
genus, Neotumularia Bondarenko, characterized by widely separated corallites and axial trabeculae
markedly inhomogeneous in size. Neotumularia also lacks vesicular skeletal plates. Dualites
Bondarenko, 1980, with closely spaced corallites, and Micrastites Bondarenko, 1980, with distant
corallites, both have septal trabeculae inclined rather than vertical, and neither was reported to
have vesicular skeletal plates. Plate 31, fig. 4 and text-fig. 4 represent a specimen (GSC 77918) from
the late Early to early Middle Caradoc Cliefden Caves Limestone Group (Kalimna Limestone
Member, Lossil Hill Limestone: Webby and Packham 1982, p. 306; Webby and Kruse 1984,
p. 165) of New South Wales that may equate with what Bondarenko (1980, p. Ill) designated D. (?)
speleana (formerly C. speleanus Hill, 1957). The transverse and longitudinal sections display the
characteristic appearance of inclined septal trabeculae; no transverse or longitudinal sections of
Ellisites showed any such indication of inclined trabeculae. Very rarely a well-preserved exterior
surface of Ellisites shows a few small radiate markings (PI. 34, fig. 3) reminiscent of the crude
septal pattern seen in the transverse section of Dualites.

Sokolov and Tesakov (1984) considered that C. astomata Llower belongs ‘beyond all shadow of
doubt’ to P. ungerni as both have striking features in common: all trabeculae are vertically arranged
and contiguous, and in consequence corallites are distinguishable only as calices on the surfaces of
corallites. Lorms herein assigned to E. astomata are clearly most similar to P. ungerni in the
character of the trabecular skeleton but, importantly, all the North American material (except for
Llower’s) has vesicular skeletal elements which are not reported in P. ungerni. Ultimately, topotypic
material of Blower’s C. astomata should be examined to see if the absence of vesicular skeletal

text-fig. 4. Coccoserid Dualitesl speleana (Hill).
GSC 77918, Lossil Hill, west of Mandurama, New
South Wales; Kalimna Limestone Member of
Fossil Hill Limestone. Tangential section showing
the radial pattern produced by inclined septal
trabeculae, x 10. See also Plate 31, fig- 4 and Plate
34, fig. 3.

406

PALAEONTOLOGY, VOLUME 29

plates is consistent in the Texas species. If such is the case, then all the other North American
specimens herein assigned to E. astomata would more appropriately be considered a new species of
Ellisites.

Flower (1961, p. 57) commented on the superficial resemblance of C. astomata to a stromato-
poroid. Of specimens herein referred to Ellisites , the first to be described were originally included
in the stromatoporoid genera Labechia Milne-Edwards and Haime, 1851 (by Foerste 1910), and
Dermatostroma Parks, 1910. D. corrugation Parks, 1910 and D. glyptum Parks, 1910 from Ohio,
and DP. escanabaense Galloway and Ehlers, 1961, from Michigan, all have a skeleton made up
solely of contiguous prisms of fibrous calcite indistinguishable in character from zones of prismatic
trabeculae in Anticosti Island Ellisites. The uncertain systematic position of these three species has
long been recognized. Galloway and St Jean (1961, p. 68) considered that they possessed \ . . no
internal characteristics of typical Dermatostroma' and indeed posed the question \ . . is
Dermatostroma a stromatoporoid?’ (ibid., p. 8). Nestor (1981, p. 23) suggested that these three
species be transferred to the Protaraeida because of their pinnate fibrous microstructure, rather
than a fibro-lamellar structure as in typical Dermatostroma and its close relative Lophiostroma
Nicholson, 1891. Their heliolitid coral affinity is now confirmed by recognition of corallites in
Anticosti Island specimens of two species. Previously described specimens of the three species of
Dermatostroma (above) lack vesicular skeletal plates.

Except for C. astomata Flower the few species ascribed to Coccoseris in the literature bear less
resemblance to the Anticosti Island species. Although internal skeletal details in some previous
species are somewhat obscured by diagenetic effects, their corallites tend to be more distinct, both
as slightly depressed calices externally and as inclined septal trabeculae in longitudinal section.

Status of Ellisites glyptum (Parks)

The name corrugata (um) was used by Foerste (July 1910, p. 86) for Richmondian specimens
assigned to Labechiaifl) from the ‘. . . Whitewater bed, along Dutch Creek, near Wilmington,
Ohio . . .’. One large specimen from the same locality was distinguished as L. (?) corrugataglypta
because of its irregular, vermiform surface ridges, and was subsequently designated a new species,
D. glyptum Foerste (1916, p. 298). Parks (October 1910) used material from the same Ohio locality
(specimens presented to the University of Toronto by A. J. Foerste) to establish his new genus and
species D. glyptum and D. corrugation , both of which had distinctive vermiculate surface ridges.

EXPLANATION OF PLATE 34

Fig. 1. Ellisites astomata (Flower). Hypotype, GSC 41177, Akpatok Island, unnamed Upper Ordovician
limestones; tangential section showing regularly spaced clusters of smaller trabeculae representing corallite
centres (compare text-fig. 3b), x 10.

Figs. 2-1. E. glyptum (Parks). 2, 3, hypotype, GSC 77915, GSC loc. 81821, Angling River, north-eastern
Manitoba, Chasm Creek Formation; tangential section (2) showing prismatic trabeculae with fibrous
microstructure, x 10; and exterior surface (3) showing one of several radial markings which superficially
resemble astrorhizal systems, but which are consistent in size and configuration with outlines of inclined
septal trabeculae within a corallite (compare with text-fig. 4), x7-5. 4, 6, hypotype, ROM 17071 (817
H.R.) (holotype of Dermatostroma corrugation Parks), Dutch Creek near Wilmington, Ohio, Whitewater
Formation; tangential (4) and longitudinal (6) sections showing prismatic trabecular structure (note that
the two growth laminae on fig. 6 grew in opposite directions), x 10. 5, holotype, ROM 17070 (816

H.R.), Dutch Creek near Wilmington, Ohio, Whitewater Formation; tangential section showing fibrous
microstructure in several trabeculae, x 10. 7, topotype, IU302-15, Dutch Creek near Wilmington, Ohio,
Whitewater Formation; longitudinal section showing fibrous microstructure in trabeculae of two thin
growth laminae, x 10.

Figs. 8 and 9. Coccoseris ? escanabaense (Galloway and Ehlers). Holotype and only known specimen, UM
39449 and thin sections IU308-98 and 308-99, Escanaba River, Delta County, Michigan, Middle Ordovician;
tangential (8) and longitudinal (9) sections, x 10.

PLATE 34

DIXON, BOLTON and COPPER, Ellisites and Coccoseris ?

408

PALAEONTOLOGY, VOLUME 29

His holotypes in the Royal Ontario Museum differ from those illustrated by Foerste (1910, pi. 1,
fig. 11; 1916, pi. 1, fig. 2). Both of Parks’s species subsequently were assigned to DP. glyptum
(Foerste) by Galloway and St Jean (1961, p. 72).

Our re-examination of these species and their nomenclatural problem made use of the following
type specimens (Foerste’s types not being located):

Type 816 H.R., University of Toronto Paleontology Collections (designated liolotype, ROM 17070, of D.
glyptum Parks 1910, p. 34).

Type 817 H.R., University of Toronto Paleontology Collections (designated liolotype, ROM 17071, of D.
corrugatum Parks 1910, p. 35).

Type 7665, slide 01-21, University of Michigan, Museum of Paleontology (designated topotype of DP
glyptum (Foerste, 1910) by Galloway and St Jean 1961, p. 73, pi. 10, fig. 2).

Slide 302-15, Indiana University Paleontology Collections (designated topotype of DP glyptum (Foerste,
1910) by Galloway and St Jean 1961, p. 73, pi. 10, fig. 4 a, b).

Slide 309-39, Indiana University Paleontology Collections (topotype of DP. corrugatum (Foerste, 1910)
from collection of Galloway and St Jean). The topotype illustrated by Galloway and St Jean (1961) is
designated slide 308-98 (apparently in error) on their p. 72, pi. 10, fig. 3a, b. The same number is quoted for a
slide of the holotype of DP escanabaense (ibid., p. 74) and the thin section of DP escanabaense also bears
number 308-98 (apparently correctly).

Type 39449, slides 01-23 and 01-24, University of Michigan, Museum of Paleontology; slides 308-98, 308-
99, and a fragment. Indiana University Paleontology Collections (designated holotype and only known
specimen of DP. escanabaense Galloway and Ehlers, in Galloway and St Jean 1961, pp. 73-74, pi. 11, fig. la,
b\ pi. 13, fig. 3).

We consider Foerste’s descriptions and illustrations (1910, pp. 86-87, pi. 1, fig. 11; 1916, pp.
298-299, pi. 1, fig. 2) of the exteriors of two specimens to be inadequate to establish species
characteristics. As the repository of his illustrated specimens is not known, we recommend that
Foerste’s trivial name corrugata (or corrugataglypta) be suppressed in favour of Parks’s first
designated name glyptum , for which an original description, illustrations, and usable holotype and
topotype material are available.

According to our present understanding of intraspecific variability in Ellisites , holotype 816
H.R. (PI. 34, fig. 5), holotype 817 H.R. (PI. 34, figs. 4 and 6), topotype 7665 and slide IU 302-15
(PI. 34, fig. 7) belong to the same species, as suggested earlier by Galloway and St Jean (1961,
p. 72), and should be referred to E. glyptum (Parks), as explained above. In addition, slide IU 309-
39, although described by Galloway and St Jean (1961, pp. 71-72) as DP. corrugatum (Foerste),
was considered by them to be probably the same species as DP. glyptum (Foerste), the latter
differing only in having vermiform surface ridges. We concur and regard this specimen as E.
glyptum (Parks). The surface ridges noted appear to be merely growth interference at the edges of
several encrusting sheets. Vesicular skeletal plates do not appear in these Ohio specimens probably
because of the very thin encrusting character of the coenosteum. Topotype 7665 has recognizable
calices on its upper surface.

Among specimens assigned in published literature to C. astomata Flower, most conform to the
group of Anticosti Island specimens herein designated E. astomata (Flower), as summarized
previously. Three others, however, are distinctly different, and their re-examination and comparison
with Parks’s types suggest that they belong to E. glyptum (Parks). Along with the previously cited
specimens of E. astomata from the Edenian Bad Cache Rapids Formation of Melville Peninsula
(Bolton 1977), is a third (GSC 42919: ibid., pi. 3, figs. 1 and 4) with distinctly larger trabeculae
(0-75-0-9 mm diameter) and rare basal vesicles. Another specimen (GSC 77916), from the Edenian-
Maysvillian Thumb Mountain Formation of the Hunting River area, Somerset Island (Dixon
1975 — GSC loc. 89518), has trabeculae 0-56-0-84 mm in diameter. Along with the previously cited
specimen of E. astomata from the Richmondian Chasm Creek Formation, Churchill River Group,
of the Nelson-Angling rivers area, north-eastern Manitoba (Cumming 1975, p. 38; GSC loc.
81821), is another colony (GSC 77915; PI. 34, fig. 2) with rare vesicles at various levels and larger
trabeculae ranging in diameter from 0-38 to 0-8 mm. One surface of this 22-0 cm wide and 3-5 cm

DIXON, ET A L. \ UPPER ORDOVICIAN HELIOLITID CORAL

409

thick colony displays minute radial markings (PI. 34, fig. 3) of a size, spacing, and arrangement
corresponding to outlines of septal trabeculae. These three specimens with larger trabeculae
compare most closely with E. glyptum (Parks).

The holotype of DP. escanabaense is a coccoserid coral and is considered at present not to belong
to Ellisites. The skeleton has solely vertical trabeculae with diameters (0-3-04 mm) and arrangement
of fibres similar to those of E. labechioides , but in contrast, the trabeculae are wholly contiguous
and the colony lacks evidence of vesicular skeletal plates (PI. 34, figs. 8 and 9). The specimen is
tentatively referred to Coccoseris and appears to be closest to forms ascribed to P. (= Coccoseris)
ungerni by Sokolov and Tesakov (1984).

Evolution

Present collecting suggests that species of Ellisites have distinctive stratigraphic ranges. From
known North American occurrences, E. astomata first appeared in the Edenian-Maysvillian and
ranged up into the Richmondian. It occurs on Anticosti Island in the uppermost Vaureal Formation
(Richmondian) along with the first E. labechioides. E. labechioides alone occurs in the lower-middle
Ellis Bay Formation (Gamachian), where it has been found as high as beds 15 m beneath the
Ordovician-Silurian boundary.

Ellisites may have evolved from a Coccoseris/ Protaraea ancestor in the mid-Ordovician by
beginning to incorporate vesicular plates in the buildup of its trabecular skeleton. The order of
stratigraphic occurrence of Anticosti Island species of Ellisites suggests further that forms such as
E. labechioides with predominantly vesicular skeletons are more likely to have evolved from earlier
species such as E. astomata (or E. glyptum) with predominantly trabecular skeletons. The vesicular
character in this group therefore appears to be a later rather than an earlier development in the
evolution of the Coccoseridicae. The hypotype of E. labechioides (GSC 77917) from the Stony
Mountain Formation of southern Manitoba, although differing somewhat from Anticosti material,
conforms to this interpreted sequence in being a predominantly vesicular Ellisites at the younger
end of the stratigraphic range of the genus in interior North America.

STROMATOPOROID RESEMBLANCES

Vesicular plates are a common space-filling device employed by various organisms in building
skeletons from a basal surface. Rudist bivalves, richthofeniid brachiopods, cryptostome bryozoans,
cystimorph rugose corals, proporid heliolitid corals, and labechiid stromatoporoids have all
included these elements in calcareous skeletons. Only in the skeletons of some stromatoporoids
and some heliolitid corals are such vesicular plates combined with vertical, rod-like trabeculae.
This combination in the Ellisitidae has implications not only for the relationship of this group to
the Proporicae but also for the discrimination of some of these corals from the conspicuously
cystose labechiid stromatoporoids. Cystostroma Galloway and St Jean in Galloway, 1957 is part of
a group including Rosenella Nicholson, 1886, Aulacera Plummer, 1843, Labechia Milne-Edwards
and Haime, 1851, and others (see Galloway 1957, p. 420) in which a fundamentally cystose skeleton
contains pillars developed to different degrees, from short denticles to long continuous rods to
absent. Larger, wholly vesicular zones of the coenosteum of E. labechioides sp. nov. (PI. 30, fig. 3;
PI. 31, fig. 2; PI. 32, fig. 2) strikingly resemble some illustrations of Cystostroma in the literature
(e.g. the upper Ordovician C. cliefdenense Webby, 1969, pi. 177, figs. 2 and 5; the middle-upper
Ordovician C. concinnum Ivanov in Bogoyavlenskaya, 1973, pi. 3, fig. 1, with small sporadic villi or
slender tubule-like pillars: Webby 1979a, p. 87).

The remarkable likeness of some of these corals to labechiids and the difficulty of distinguishing
them is also illustrated by the specimens of E. labechioides referred by Bolton (1981, p. 42, pi. 1, fig.
4; pi. 2, figs. 1 and 2) to Labechia n. sp. aff. L. mirabilis-L. banksi group. Coenostea from the late
Ordovician of Kolyma Basin, north-eastern USSR, consist of intergrowths of what have been
defined as L. mirabilis Yavorsky and C. rarum Yavorsky (1961, pi. 19, figs. 2-6; pi. 20, figs. 1 and
2) that in many aspects appear similar to Ellisites, but the impersistent pillars are non-tubercular.

410

PALAEONTOLOGY, VOLUME 29

L. banksi Webby, 1979 similarly exhibits Cystostroma-like bands within normally cystose —
denticulate— discretely pillared coenostea (Webby 1979 b, p. 244).

Labechiids and other stromatoporoids, however, possess characteristic astrorhizal systems that
cannot be explained in terms of a corallite structure. Astrorhizae have not been distinguished in
any of the numerous well-preserved specimens of Ellisites. Minute radial grooves on the exterior of
one of the specimens referred to E. glyptum (PI. 34, fig. 3) bear a superficial resemblance to
astrorhizae, but their size and configuration are consistent with them being the outlines of inclined
septal trabeculae (their margins possibly emphasized by ground water solution). A comparable
pattern of very similar size and character is shown by inclined septal trabeculae in a tangential
section of a coccoserid from New South Wales (text-fig. 4).

Labechia developed long pillars in a cystose skeleton. The pillars are composed of \ . . loosely
aggregated granular material . . (Galloway and St Jean 1961, p. 7), different from the pinnate
fibrous microstructure of Ellisites , although diagenesis can reduce the latter to a dark granular
texture not readily distinguishable from pillars in labechiids. Labechia shows some tendency for
pillars to fuse along lateral surfaces (Bogoyavlenskaya 1971, p. 32) but far short of the extent
shown by Elllisites. In most labechiids the initiation of pillars is staggered, although some (e.g. the
Wenlock L. communis Yavorsky, 1963, pi. 9, fig. 3) show short pillars tending to begin at common
levels. In all astogenetic stages of most genera (some species of Aulacera being exceptions), pillars
appear to be the same in length, width, and number (Galloway 1957, p. 371). In contrast, Ellisites
shows marked astogenetic change: most trabeculae begin at corresponding levels, and constitute
sharply defined growth zones that are generally more frequent with maturity (e.g. PI. 30, figs. 1 and
4; PI. 31, fig. 2). Finally, some labechiids show differentiation of cysts into columns (e.g. by size in
Cystostroma: see Bogoyavlenskaya 1973, p. 19). An analogous feature in Ellisites is the differentia-
tion, in sectors of vesicular plates, of what are interpreted as columns of incomplete tabulae (in
corallites) with intervening dissepiments (in coenenchynre).

In summary, the skeletons of Ellisites and labechiid stromatoporoids are very similar in combining
vertical rod-like trabeculae and vesicular plates and in the character and disposition of these
skeletal structures. In some well-preserved specimens of Ellisites , the presence of corallite calices,
the internal arrangement of trabeculae suggestive of corallites separated by coenenchynre, and the
absence of astrorhizal systems are characteristics of heliolitid corals rather than stromatoporoids.

CONCLUSIONS

1 . Dermato stromal escanabaense Galloway and Ehlers, D. corrugatum Parks, and D. glyptum
Parks are interpreted as heliolitid corals rather than stromatoporoids, and are therefore excluded
from Dermatostroma Parks.

2. D. glyptum and D. corrugatum are considered to be synonymous and are removed to a new
genus, Ellisites , as E. glyptum , through comparison with material designated E. labechioides sp.
nov. and E. astomata (Flower) from Anticosti Island.

3. Ellisites gen. nov. is placed in the Ellisitidae fam. nov., in the superfamily Coccoseridicae, and
is interpreted as a phylogenetic link between this group and the Proporicae.

4. Earlier species such as E. glyptum and E. astomata (both Edenian to Richmondian) have
predominantly trabecular skeletons with minor vesicular plates; the younger E. labechioides
(Richmondian-Gamachian) has a strongly vesicular skeletal construction that deceptively mimics
the characteristic cystose structure of labechiid stromatoporoids.

Acknowledgements. This study was financially assisted by Operating Grants of the Natural Sciences and
Engineering Research Council of Canada. The authors thank Colin Stearn for comments and suggestions on
the manuscript in its final stages, Edward W. Hearn for photographic work on Anticosti Island collections,
and Julie Hayes for manuscript typing. The loan of type specimens was kindly arranged by J. Waddington
(Royal Ontario Museum), J. St Jean (University of North Carolina), and P. D. Gingerich (University of
Michigan).

DIXON, ET A L.: UPPER ORDOVICIAN HELIOLITID CORAL

41 I

REFERENCES

Bogoyavlenskaya, o. v. 1971. Ordovikskie i siluriyskie labekhiidy Tuvy. Paleont. Zh. 1971 (3), 32-38. [In
Russian.]

— 1973. Ordovikskie stromatoporoidei zapadnogo sklona Urala. Ibid. 1973 (4), 18-24. [In Russian.]

— and boyko, e. v. 1979. Sistematicheskoye polozheniye stromatoporat. Ibid. 1979 (1), 22-35. [In Russian.]
bolton, t. e. 1972. Geological map and notes on the Ordovician and Silurian litho- and biostratigraphy,

Anticosti Island, Quebec. Geol. Surv. Pap. Can. 71-19, 44 pp.

— 1977. Ordovician megafauna, Melville Peninsula, southeastern District of Franklin. Ball. geol. Surv.
Can. 269, 23-75.

1981. Ordovician and Silurian biostratigraphy, Anticosti Island, Quebec, In lesperance, p. j. (ed. ).
Subcommission on Silurian Stratigraphy , Ordovician- Silurian Boundary Working Group , Field Meeting ,
Anticosti-Gaspe , Quebec , 1981. Vol. II: Stratigraphy and Paleontology , 41-59.

Bondarenko, o. b. 1967. K. istorii razvitiya geliolitoidei v Kazakhstane. Vest. Mosk. Univ., ser. 4, Geol. 22
(3), 39-50. [In Russian.]

— 1980. O statuse rodov Protaraea-Coccoseris-Diplastraea-Tumularia (korally Ordovika). By ul. Moskov.
O-va Ispyt. Prirodv Otd. Geol. 55 (6), 102-1 13. [In Russian ]

cocks, l. r. m. and copper, p. 1981. The Ordovician Silurian boundary at the eastern end of the Anticosti
Island. Can. J. Earth Sci. 18, 1029-1034.

cumming, l. m. 1975. Ordovician strata of the Hudson Bay Lowlands. Geol. Surv. Pap. Can. 74-28, 93 pp.
dixon, j. 1975. Ordovician and Silurian fossils from the Lang River and Allen Bay Formations of Prince of
Wales and Somerset Islands, Northwest Territories. Bull. Can. Petrol. Geol. 23, 172-184.
flower, r. h. 1961. Montoya and related colonial corals. Mem. Inst. Min. Technol. New Mex. 7, 97 pp.
foerste, A. F. 1909. Preliminary notes on Cincinnatian fossils. Bull, scient. Labs Denison Univ. 14, 209-228.

— 1910. Preliminary notes of Cincinnatian and Lexington fossils of Ohio, Indiana, Kentucky and Tennessee.
Ibid. 16, 17-100.

1916. Notes on Cincinnatian fossil types. Ibid. 18, 285-355.

galloway, s. j. 1957. Structure and classification of the Stromatoporoidea. Bull. Am. Paleont. 37, 343 480.

— and st jean, j. 1961 . Ordovician Stromatoporoidea of North America. Ibid. 43, 1-103.
hall, j. 1847. Palaeontology of New York , Vol. 1. In Natural History of New York , Part VI, xxiii + 338 pp.
Carroll and Cook, Albany.

hill, D. 1957. Ordovician corals from New South Wales. ./. Proc. R. Soc. N.S. W. 91, 97- 107.

— 1981. Rugosa and Tabulata. In robinson r. a. and teichert, c. (eds.). Treatise on Invertebrate
Paleontology , Part F, Coelenterata , Supplement 7, xl + 762 pp. Geological Society of America and University
of Kansas Press, New York and Lawrence, Kansas.

lake, j. h. 1981. Sedimentology and paleoecology of Upper Ordovician mounds of Anticosti Island, Quebec.
Can. J. Earth Sci. 18, 1562-1571.

mccracken, a. d. and barnes, c. r. 1981. Conodont biostratigraphy and paleoecology of the Ellis
Bay Formation, Anticosti Island, Quebec, with special reference to Late Ordovician-Early Silurian
chronostratigraphy and the systemic boundary. Bull. geol. Surv. Can. 329, 51-134.
milne-edwards, j. and haime, j. 1851. Monographic des polypiers fossiles des terrains paleozolques. Archs
Mus. Hist. nat. Paris, 5, 1-502.

nestor, h. e. 1966. Wenlockian and Ludlovian Stromatoporoidea of Estonia. Inst. geol. akad. nauk Estonskoy
SSR, 87 pp.

1981. The relationships between stromatoporoids and heliolitids. Lethaia , 14, 21 25.
norford, b. s. and macqueen, r. w. 1975. Lower Paleozoic Franklin Mountain and Mount Kindle
Formations, District of Mackenzie: their type sections and regional development. Geol. Surv. Pap. Can.
74-34, 37 pp.

nowlan, g. s. and barnes, c. r. 1981. Late Ordovician conodonts from the Vaureal Formation, Anticosti
Island, Quebec. Bull. geol. Surv. Can. 329, 1 -50.
parks, w, a, 1910. Ordovician stromatoporoids. Univ. Toronto Stud, geol Ser. 7, 1-52.

petryk, a. a. 1979. Stratigraphie revisee de Pile d’Anticosti. Min. Energie Ress., Dir. gen. Energie, Serv.
Exp I or., publ. DPV-71 1, 24 pp.

— 1981. Stratigraphy, sedimentology and paleogeography of the Upper Ordovician-Lower Silurian of
Anticosti Island, Quebec. In lesperance, p. j. (ed.). Subcommission on Silurian Stratigraphy, Ordovician
Silurian Boundary Working Group, Field Meeting, Anticosti-Gaspe, Quebec, 1981, Vol. II: Stratigraphy and
Paleontology, 1 1 -39.

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PALAEONTOLOGY, VOLUME 29

scrutton, c. T. 1984. Origin and evolution of tabulate corals. Palaeontogr. am. 54, 110-118.

SOKOLOV, B. s. and tesakov, yu. i. 1984. Populyatsionnyi, biotsenoticheskiy i biostratigraficheskiy analiz
tabulat. Podol'skaya model'. Akad. nauk SSSR , Sibir. Otdel ., Inst. Geol. Geofiz. 577 . [In Russian.]
stearn, c. w. 1982. The unity of the Stromatoporoidea. Proc. Third N. Amer. Paleont. Corn. 2, 51 1-516.
trettin, h. p. 1975. Investigations of Lower Paleozoic geology, Foxe Basin, northeastern Melville Peninsula,
and parts of northwestern and central Baffin Island. Bull. geol. Surv. Can. 251, 143 pp.
webby, B. D. 1969. Ordovician stromatoporoids from New South Wales. Palaeontology , 12, 637-662.

1979a. The Ordovician stromatoporoids. Proc. Linn. Soc. N.S.W. 103, 83-121.

19796. The oldest Ordovician stromatoporoids from Australia. Alcheringa , 3, 237-251.

-and kruse, p. d. 1984. The earliest heliolitines, a diverse fauna from the Ordovician of New South
Wales. Palaeontogr. am. 54, 164 168.

-and packham, G. H. 1982. Stratigraphy and regional setting of the Cliefden Caves Limestone Group
(Late Ordovician), central-western New South Wales. J. geol. Soc. Aust. 29, 297-317.
workum, r. h., bolton, t. e. and barnes, c. R. 1976. Ordovician geology of Akpatok Island, Ungava Bay,
District of Franklin. Can. J. Earth Sci. 13, 157-178.

yavorsky, v. i. 1961. Stromatoporoidea Sovetskogo Soyuza, Pt. 3. Trudy vses. nauchno-issled. geol. Inst.
(n.s.), 44, 63 pp. [In Russian.]

1963. Stromatoporoidea Sovetskogo Soyuza, pt. 4. Ibid. 87, 160 pp. [In Russian.]

OWEN A. DIXON

Ottawa-Carleton Centre for Geoscience Studies
Department of Geology
University of Ottawa
Ottawa, Canada KIN 6N5

THOMAS E. BOLTON
Director General's Office
Geological Survey of Canada
Ottawa, Canada K1A 0E8

PAUL COPPER
Department of Geology

Typescript received 15 May 1985 Laurentian University, Sudbury

Revised typescript received 20 September 1985 Ontario, Canada P3E 2C6

APPENDIX

ANTICOSTI ISLAND LOCALITIES

Studied material was collected by T. E. Bolton— ‘BF’ collections (numbers in parentheses) at localities 2, 3, 4,
and 16; by O. A. Dixon— 'J', 'M\ and 'Q' collections at localities 1, 5, and 16; by R. Sanschagrin — locality 3c;
and by P. Copper— ‘A’ collections at localities 3c and 6 to 15.

1. Main highway, 40 km from Port Menier, at Ste Marie River. NTS Lac Faure 12E/13W, 3795 : 1890.
Upper Vaureal Formation (M2-74). Ellisites astomata.

2. GSC loc. 36269. Jupiter River road (1958), 0-8 km south of main highway. NTS Anse de la Sauvagesse
12E/14, 6475 : 1245. Upper Vaureal Formation (BF82A). E. astomata.

3a. GSC loc. 36146. Main highway, 77-6 km from Port Menier. NTS Anse de la Sauvagesse 12E/14, 7025 :
1290. Upper Vaureal Formation (BF18). E. astomata , E. labechioides.

3b. GSC loc. 66774. Main highway, 1-6 km east of Jupiter River road (1964). NTS Anse de la Sauvagesse
12E/14, 7110: 1210. Upper Vaureal Formation (BF188). E. labechioides.

3c. GSC loc. 76087. Main highway, 11 km east of Beaver Cove road. NTS Anse de la Sauvagesse 12E/14,
7388 : 1080. Upper Vaureal Formation (BF229D; A14). E. astomata , E. labechioides.

4. GSC loc. 76091. Loon Lake Bear Lake road, just south of junction with main highway. NTS Lac
Wickenden I2E/1 1, 7545 : 1020. Upper Vaureal Formation (BF229B). E. labechioides.

DIXON, ET AL.\ UPPER ORDOVICIAN HELIOLITID CORAL

413

5. McDonald Fire Tower-Jupiter River road, 11 km south of main highway. NTS Lac Wickenden 12E/1 1,
8430-8445 : 0650-0690. Upper Vaureal Formation (Q 10-74). E. astomata, E. labechioides.

6. Coastal cliff, waterfall, and tidal flat exposures in Mill Bay, 1-2 km east of Schmitt Creek. NTS Broom
Bay 1 2E/8, 6780 : 7052( A202), 6620-6750 : 6960-7300( A365a). Upper Vaureal Formation, loose collection
from cliffs (A202) and approximately 7-8 m below top (A365a). E. astomata.

7. Coastal exposures in Mill Bay, I km west of Schmitt Creek. NTS Broom Bay 12E/8, 6470-6580 : 6960-
7020. Upper Vaureal Formaton, 3-5 m below top (A364/1 ^Copper) or basal Ellis Bay Formation
(Bolton). E. astomata.

8. Tidal flat exposures at base of Prinsta Point cliff, 2 km north of Prinsta River. NTS Cap de la Table
12F/5, 7453:6811. Upper Vaureal Formation, uppermost 2 m (A133 — Copper) or basal Ellis Bay
Formation (Bolton). E. astomata.

9. Prinsta Point, loose blocks from cliff about 8-5 m above tidal flat. NTS Cap de la Table 12F/5, 7443 :
6775. Ellis Bay Formation, at least 19-5 m above base (A212). E. labechioides.

10. Shoreline and tidal flat exposures at base of waterfall, Prinsta Bay, about 2 km east of Prinsta River
mouth. NTS Cap de la Table 12F/5, 7615 : 6618. Ellis Bay Formation, 20-21 m below Ellis Bay/Becscie
formational boundary of Cocks and Copper ( 1981 ) (A 138; A213). E. labechioides.

1 1 . Coastal cliff and tidal flat exposures from west of Lousy Cove creek toward Table Head. NTS Cap de la
Table 12F/5, 8085-8087 : 6488-6495. Ellis Bay Formation, approximately 25 m below Ellis Bay/Becscie
formational boundary of Cocks and Copper (1981 ) (A219). E. labechioides.

12. Coastal cliffs about 1 km south of Table Head Lighthouse. NTS Cap de la Table 12F/5, 8052 : 6596.
Same horizon as locality 1 1 (A220). E. labechioides.

13. Tidal flat exposure, north side of mouth of Table Head Creek. NTS Cap de la Table 12F/5, 8092 : 6478.
Same horizon as locality 1 1 (A315; A357/2). E. labechioides.

14. Low cliff exposures, south side of mouth of Table Head Creek. NTS Cap de la Table 12F/5, 8096 : 6468.
Ellis Bay Formation, 21 m below Ellis Bay/Becscie formational boundary of Cocks and Copper (1981)
(A218). E. labechioides.

15. Low cliff exposures, east side of Prinsta River mouth. NTS Cap de la Table 12F/5, 7448 : 6645. Ellis Bay
Formation, 15 m below Ellis Bay/Becscie formational boundary of Cocks and Copper (1981) (A135). E.
labechioides.

16. GSC Iocs. 84385 and 92401. Vaureal River, 3-8 km south-south-west from Vaureal Falls. NTS Carleton
Point 12E/10, 2045 : 8630. Ellis Bay Formation, member 4 (BF403; J2-74). E. labechioides.

ARCHOSAUR PREDATION ON AN EAST
AFRICAN MIDDLE TRIASSIC DSCYNODONT

by A. R. I. CRUICKSHANK

Abstract. A description is given of two sets of tooth impressions on the shaft of a kannemeyeriid dicynodont
femur from the Middle Triassic (Anisian) Manda Formation of the Ruhuhu Valley, Tanzania. A brief analysis
of the dentition is attempted and it is concluded that these impressions were probably made by a rauisuchid
thecodontian, for which the name Mandaodonites coxi is proposed.

The fauna of the Middle Triassic Manda Formation, in the Ruhuhu Valley of Tanzania is
becoming better known (Stockley 1932; Anderson and Cruickshank 1978), but as yet formalized
descriptions of the archosaur component of the fauna is restricted to two genera established over
forty years ago by von Huene (1938, 1939). One, Stcigonosuchus , is a large rauisuchid and the other,
Parringtonia , is a representative of the smaller Erpetosuchidae (Krebs 1976). The remnants of both
these forms are incomplete and contain only scraps of skull material. Thus comparisons of their
dentitions with the phenomena described below are not possible. More complete material is
available, but awaits formal description (Attridge et al. 1964; Charig 1957, 1967, 1971). Other
evidence for the large archosaurs in the Manda Formation and evidence for relationships with
possible prey species is of some interest and has prompted the descriptions which follow. The tooth
impressions recorded here have been given ichnogeneric and ichnospecific names purely as a device
to aid reference later on when the entire fauna will be reviewed.

While preparing the skull and post-cranial skeleton of a kannemeyeriid dicynodont (Cruickshank,
1986) it was noted that the right femur was badly split and that the matrix-filled crack ran
obliquely across the long axis of the shaft of the bone (text-fig. 1). Careful cleaning away of this
matrix revealed that the crack was in fact a linear series of depressions of variable diameter (text-
fig. 2; Table 1 ), most obvious on the ventral surface of the femur where about 16 of these markings,
oval, round, or irregular in outline, could be seen. On the dorsal surface about 17, similar but less
deep, markings are preserved. At one point on the shaft and at the ends where the lines of marks
cross the edges of the femur, the opposing depressions meet right through the bone (text-fig. 2b, c).
Thus the head of the femur is pulled obliquely away from the shaft of the bone. When traced on to
paper the lines of depressions follow sigmoidal curves (text-fig. 3).

SYSTEMATIC PALAEONTOLOGY

Class REPTILIA
Subclass DIAPSIDA
Infraclass archosauria
Order thecodontia
Family rauisuchidae
Ichnogenus Mandaodonites gen. nov.

Diagnosis. A dentition of conical, variable-sized teeth giving a sigmoidal curve when impressed into
a resistant substrate. Each tooth row is at least 16 00 cm long; teeth are inferred to average 6T2
mm in diameter on one row and 7-47 mm in the other. Maxima and minima are 10-5 mm and 3-5
mm. The teeth may occur in triplets, reflecting replacement cycles.

Derivation of name. From the Manda Formation, Songea District, Southern Province, Tanzania.

IPalaeontology, Vol. 29, Part 2, 1986, pp. 415-422.]

416

PALAEONTOLOGY, VOLUME 29

Type Ichnospecies. Mcindaodonites coxi sp. nov.

Diagnosis. As for genus.

Derivation of name. In honour of Professor C. B. Cox, who has worked extensively on the Manda fauna and
for his incisive contributions to vertebrate palaeontology.

Holotype. Impressions in specimen number T1225, a dicynodont right femur, in the collections of the
University Museum of Zoology, Downing Street, Cambridge, England.

Horizon and locality. The material was collected by Nowack (1937) from his locality 328, which lies between
the M’himbasi and N’datira Rivers, to the east of the mission at Litumba, Songea District, Tanzania. Each of
Nowack’s localities has produced several individual fossils, the numbering of which follows the scheme
introduced for the CUMZ collections of fossil tetrapods.

Method. Preparation was by dental mallet, with extra detail worked out with an industrial airbrasive machine.
However, the bone was softer than the matrix in most places and thus little could be added with this technique.

text-fig. 1. Dorsal (left) and ventral (right) views of dicynodont femur, CUMZ
T1225, showing oblique lines of impressions on the shaft of the bone. Crack-patterns
on the bone surface, other than the presumed tooth marks, are semi-diagrammatic.
Note, however, the series of radial and concentric cracks centred on tooth position
10 on the ventral surface. Scale bar is 5 cm.

CRUICKSHANK: ARCHOSAUR PREDATION

417

In analysing the impressions several techniques were attempted. In the first, the outlines of the impressions
were transferred to paper using a kind of 'brass rubbing’ method. Paper was placed over the impressions and
rubbed with a soft (B) pencil. The outline thus obtained was transferred to another piece of paper using
carbon paper. However, it was difficult to obtain a satisfactory, true, outline of the 3-D object on flat paper
using this method, and eventually a photocopy was made of the femur on a Sharp photocopier for analysis.
From these diagrams tooth number and jaw outline were obtained (text-figs. 2 and 3; Table 1), and as
discussed below, an attempt at reconstruction of the tooth row was possible. The second investigation
involved casting the impressions to see if further detail of tooth morphology could be obtained. De Trey
Reprosil silicone-based elastomeric impression material was syringed into the depressions, and when cured,
backed by a rigid thermoplastic material. This gave a reasonably good reproduction of the tooth impressions,
especially the form of one tooth from the dorsal surface of the femur, and here called position 10 on the
reconstruction. However, a softer silicone rubber, GEC RTV 700, gave a reproduction of greater fidelity and
did not require the rigid backing. The illustrations of the casts are taken from a combination of both attempts
(text-figs. 2 and 3).

Transverse diameters of the depressions were measured using a pair of dividers and an engineer’s metal
rule (Table 1 ).

table 1. Mandaodonites coxi gen. et sp. nov. Measurement
of tooth impression diameters.

Ventral surface of femur Dorsal surface of femur

Tooth position 1

4-5 mm

1

7 0 mm

2

5-5

2

9-5

3

6-5

3

4-0

4

60

4

80

5

6-5

5

90

6

90

6

4-5

7

7-5

7

5-5

8

7-0

8

4-5

9

50

9

50

10

70

10

50

1 1

100

1 1

100

12

10-5

12

4-5

13

9-5

13

3-5?

14

100

14

60

15

80

15

4-5

16

7-0

16

7-0

17

7-0?

X

= 7-47 mm

X

= 612 mm

Numbered from head end of femur. Measurements to
nearest half mm.

DESCRIPTION OF MATERIAL

The holotype of Mandaodonites coxi is a series of impressions forming a pair of sigmoidal curves
laying on the opposite sides of the shaft of a dicynodont femur. The impressions on the dorsal
surface are much less well marked than those on the ventral surface. Perhaps seventeen tooth
positions can be represented on the dorsal surface and sixteen on the ventral. On the dorsal surface
the diameter of the impressions ranges from 10 0 mm to 3-5 mm, with a mean of 612 mm. Tooth
position 10, a 5-0 mm diameter mark, coincides with a break in the femur and this impression links
with the corresponding mark on the ventral surface (also number 10). It also seems to retain the

418

PALAEONTOLOGY, VOLUME 29

14 10 3

text-fig. 2. a, Mandaodonites coxi gen. et sp. nov. Interpretation of the impressions on the ventral
surface of the femur and here assigned to the premaxillary/maxillary dentition. Numbered from the
head end of the femur. Premaxillary tooth marks may be represented by positions 1-3. Reversed
left-for-right. b , ‘outer’ view of silicone rubber cast of impressions from ventral surface. Not all the
impressions are represented on this cast, c, similar representation of the cast taken from the dorsal
surface, d , interpretation of the impressions on the dorsal surface of the femur. The symphysis of the
dentary is assumed to cover tooth positions 1-3.

‘Upper’ tooth position 14 and ‘Lower’ tooth position 10 indicate that their originals were conical
and recurved. ‘Upper’ tooth positions 13; 4-6; 7-8; 9-11; 12-14 may be grouped into replacement
triplets. ‘Lower’ tooth positions 1-3; 4-6; 7-9; 10-13; 16-17 may be similarly grouped.

Arrows on dotted lines link opposing points on the dentition, (p-line drawn parallel to reconstructed
jaw centre-lines. Scale bar is 5 cm. Heavy arrow points toward head of femur.

CRUICKSHANK: ARCHOSAUR PREDATION

419

best shape of any of the preserved impressions, and hence would seem to have been made by a
recurved conical tooth of crown height 17 0 mm. The apex of the tooth curves towards the distal
end of the femur and indicates the orientation of the dentition, reinforcing the interpretation given
below. No fine detail of any of the teeth is preserved. Of the other tooth impressions on the dorsal
surface of the femur, the three anteriormost, i.e. those nearer the head of the femur, are well
marked. The fourth to seventh positions are faintly seen, and the eighth and ninth positions
are shallow with moderate diameters. Position 10 has pierced the bone to contact the opposing
number, as indicated above, as do positions 16/17. Positions 11 and 12 are complex, but as
they also coincide in part with the same break in the femur which affects 10, damage to the bone
might account for this complexity. All the remaining tooth positions are moderately to well
seen, and almost of constant diameter. It is possible that tooth positions 10-12 represent a
Triplet’ of replacing teeth, as do 15-17 of this side. Similar Triplets’ are better seen on the opposing
dentition.

Although the impressions on the ventral surface are the more deeply incised, they do not seem to
be as well preserved. About sixteen positions can be identified. The size range of their diameters is
much the same as for the dorsal surface, but the mean is 7-47 mm. It would seem that all the teeth
on the jaw ramus represented by these marks left impressions, with positions 9-1 1 being the most
deeply incised. Tooth position 14 shows some slight recurvature, in the same direction as number
10 on the opposite side.

In both sets of impressions the marks are almost all round, or slightly oval, with the long axes of
the latter cases running obliquely across the line of the dentitions, in an anterobuccal-posterolingual
direction. This seems to follow the situation in known rauisuchids, where the dentitions are
adequately described (M. J. Benton pers. comm.). The overall impression gained from an
examination of these marks is that they represent the effect of a powerful dentition being closed on
the shaft of the femur of this dicynodont.

Interpretation of the dentition and the bite. When the impressions are reconstructed to give
complete outlines of the tooth rows of each jaw, an interpretation of the dentitions can be given as
follows. Tooth position 10 on the dorsal surface of the femur is offset from its counterpart on the
ventral surface by about 10 cm medially and T5 cm posteriorly, the orientation being based on the
known recurvature of the impressions at tooth positions 10 on top and bottom surfaces. This then
gives the relative positions of the two tooth rows, the one fitting inside the other when the
reconstructions are made (text-fig. 3). In establishing bilateral symmetry for the tooth rows, not
only must this offset be taken into account, but they must also be reconstructed with a smooth
profile at the symphysis and premaxillae. When these two factors are taken into account the main
portions of the reconstructed jaw rami are almost parallel, and with the more abrupt curvature
being at the front, reinforces the interpretation of the lower jaw having made the marks on the
dorsal surface and vice versa.

It therefore follows that the bite was made with the right side of the jaw, with the prey lying on
its back and the femur probably still attached to the carcase. If it were otherwise, then the
presumption is that the femur would have been separated from the body of the dicynodont, a
situation which seems unlikely from further analysis. Thus although the distal condyles of the
femur span 14 cm, the reconstructed dentitions are only very slightly less at the back, and it is
therefore quite possible to fit the femur into the mouth of a predator of this dimension, with the
epipodials having been ripped off. The head of the femur is more than 16 cm wide at its greatest,
and it is felt that, even allowing for the uncertainties of this reconstruction, this would have been
too much to have been taken into the mouth. Even if the femur had been inserted into the mouth
head first, then there would have to be tooth marks on the trochanter major area of the femur, and
none are seen.

Therefore the dicynodont was probably lying on its back, having had the epipodials of the right-
hind limb removed before the bite affecting the femur was made. The lesser depth of the impressions
towards the head of the femur are thought to be the result of the jaws not being able to close with
the leg bone jamming them open.

420

PALAEONTOLOGY, VOLUME 29

on jaw outlines indicate corresponding points on the lines of impressions. ‘Lower’ jaw fitting

inside ‘Upper’. Scale bar is 5 cm.

IDENTITY OF THE PREDATOR

Unlike the mosasaur tooth marks on an ammonite shell, where several bites had been made on
that prey (Kauffman and Kesling 1960), here there is evidence for only one bite, albeit one of
substantial force. As can be seen from text-fig. 1, the crack in the femur has split the anterior edge
away from the main body of the bone. It could be argued that these depressions were alternatively
the result of hard nodules or similar pieces of rock pushing into the bone and so causing the crack
(Brain 1981). Other phenomena causing cracking in bone are sun-damage caused by exposure to
the elements before burial, and tectonic events post-burial. In this specimen, when the femur was
cleaned, there was no evidence of any kind of hard objects on or near the impressions. It is
therefore considered unlikely that these impressions, in a long line, on both surfaces of the shaft of
the femur, could have been caused by such hard objects as rocks or nodules. However, there are
both circular and radial cracks centred on some of the pits which do indicate that they were caused
by some object pressing very hard on the bone, and of which no direct evidence remains, e.g.
positions 10-12 on the ventral surface of the bone. These can be distinguished from sun-cracks on
the surface of the bone, which are formed as marks of varying width, but at the same time forming
a grid-like pattern on the bone surface (Kitching 1977, pi. 4). Tectonic damage seems unlikely as
the femur in its overall form and proportions seems to be undisturbed away from the line of the
depressions and pits. In summary, the main damage is entirely localized around the centres of the
depressions and the best explanation seems to be that the two rows of impressions were caused by
opposing rows of teeth closing with some force on the shaft of the femur.

CRUICKSHANK: ARCHOSAUR PREDATION

421

Another problem is to assign these marks to one or other taxonomic group, as the perpetrator.
Possible contenders for the maker of these impressions, in the Manda Formation, would lie within
the Cynodontia (Crompton 1956, 1972), the stereospondylous Amphibia (Howie 1970), and the
thecodontian Archosauria (von Huene 1938, 1939). The cynodonts provide an unlikely solution to
the problem, as they seem not to have had a dentition which could have made these marks, and
although their tooth rows are sigmoidal in outline, they were shorter than those represented here.
In any case the larger of the cynodonts in the Manda Formation are ‘gomphodonts’ and hence
probably herbivores and the presumed carnivores (Aleodon Crompton and Cricodon Crompton)
are too small. The stereospondyl amphibians are also an unlikely cause of the damage as their
dentitions are not only very much longer than is represented here, but their maxillae are straight,
as opposed to having the sigmoidal curve preserved in these tooth rows. Their teeth are closely
packed, transversely oval, and very much shorter anteroposteriorly than those which made the
marks preserved here. The remaining group, the archosaurs, are represented by two described
genera (and the unknown forms) in the Manda Formation and of which only the larger genus
would be appropriate (Stagonosuchus Huene).

table 2. Tooth counts for known rauisuchids are as follows (data
from Bonaparte (1971), Romer (1971), Krebs ( 1 976), and Dawley
et at. (1979)).

PMX

MX

DENT

Rauisuchus

6

Ticinosuchus

6?

9 =

15?

17

Prestosuchus

3

—

12

Saurosuchus

4

13? =

17?

10

Luperosuchus

4?

9? =

13?

— (from reconstruction)

Heptasuchus

3

9? =

12?

—

The biggest problem in assigning these tooth marks to the archosaurs is the sigmoidal tooth row
as indicated by the impressions on this femur (text-figs. 2 and 3). Most thecodontians have arcuate
dentitions rather than sigmoidal (Krebs 1976). However, Ornithosuchus (Walker 1964) and the
crocodilians do have slightly sigmoidal dentitions, the latter more so than the former. It is unlikely
that this set of impressions was made by a crocodilian, as not only is the Manda Formation too old
for all known crocodilians (Anderson and Cruickshank 1978), but the tooth-row impression left
here is too long for their early representative. Ornithosuchus is also an upper Triassic genus and
hence it or a relative would be unlikely candidates. The Ornithosuchidae appear to have a ‘diastema’
in their upper tooth rows, of which there is no evidence here. However, it could also be argued that
a thecodontian biting into a very resistant object would have the tooth-row distorted by the
pressure of the bite acting through hinge points in the skull (Walker 1972), and so produce an
impression with a sigmoidal outline.

In summary, the upper tooth row ranges from twelve to seventeen positions and the lower
ranges from ten to seventeen positions. The tooth positions recorded for Mandaodonites lie within
the ranges for the known rauisuchids, but notwithstanding this interpretation, it is also very
possible that one or other of the undescribed forms from the Manda Formation might have made
these impressions and whose identity is wholly unknown.

Mandaodonites co.xi is seen as representing a medium-sized thecodontian, possibly a rauisuchid,
which preyed on the pig-sized dicynodonts of the Manda Formation. The dicynodont skull
associated with the femur is edentulous, which may indicate that it belonged to a nocturnal animal
(Cruickshank 1978). If this was so, then perhaps Mandaodonites was also nocturnal, unless it
surprised the dicynodont in its daytime cover.

422

PALAEONTOLOGY, VOLUME 29

Acknowledgements. Messrs. T. B. Hamilton, Dental Surgeon, and M. Moore of Teviotdale Design, Hawick,
for making casts of the impressions. Dr Alec Panchen for the use of his airbrasive machine and discussion; Dr
Alick Walker for the use of his literature and discussion and Drs M. J. Benton and T. S. Kemp for discussion.
Dr J. Hopson contributed encouraging confirmation on rauisuchid jaw morphology. Finally and particularly.
Dr K. A. Joysey for giving me access to the fossil collections in the University Museum of Zoology in
Cambridge and permitting me to describe this material.

REFERENCES

anderson, j. m. and cruickshank, a. r. i. 1978. The biostratigraphy of the Permian and the Triassic. Part 5.

A review of the classification and distribution of Permo-Triassic tetrapods. PalaeontoL afr. 21, 15-44.
attridge, j., ball, H. w., charig, a. j. and cox, c. b. 1964. The British Museum (Natural Historyj-University
of London joint palaeontological expedition to Northern Rhodesia and Tanganyika, 1963. Nature, Lond.
201,445-449.

bonaparte, j. f. 1971. Annotated list of the South American Triassic tetrapods. In haughton, s. h. (ed.).

I.U.G.S. Second Gondwana Symposium, 1970, pp. 665-682. C.S.I.R., Pretoria.
brain, c. K. 1981. The hunters or the hunted? An introduction to African cave taphonomy. The University
Press, Chicago.

charig, a. j. 1957. New Triassic archosaurs from Tanganyika, including Mandasuchus and Teleocrater. Ahstr.
Diss. Univ. Camb. 1955-1956, 28-29.

— 1967. Subclass Archosauria. In Chapter 28, Reptilia (The Fossil Record, Part 11), pp. 708-718. The
Geological Society of London.

— 1971. Faunal Provinces on land: evidence based on the distribution of fossil tetrapods, with especial
reference to the reptiles of the Permian and Mesozoic. In middlemiss, f. a., rawson, p. f. and new all, g.
(eds.). Faunal Provinces in Space and Time, pp. 111-128. Geological Journal Special issue no. 4. Seal House
Press, Liverpool.

Crompton, a. w. 1956. Some Triassic cynodonts from Tanganyika. Proc. zool. Soc. Lond. 125, 617-669.

— 1972. Postcanine occlusion in cynodonts and tritylodonts. Bull. Br. Mus. (Nat. Hist ), 21, 30-69.
cruickshank, a. r. i. 1978. Feeding adaptations in Triassic dicynodonts. PalaeontoL afr. 21, 121-132.

— 1986. Biostratigraphy and classification of a new Triassic dicynodont from East Africa. Modern Geology,
10, in press.

dawley, r. m., zawiskie, j. m. and cosgriff, j. w. 1979. A rauisuchid thecodont from the Upper Triassic
Popo Agie Formation of Wyoming. J. Paleont. 53, 1428-1431.
howie, a. a. 1970. A new capitosaurid labyrinthodont from East Africa. Palaeontology , 13, 210-253.
huene, f. von. 1938. Ein grosser stagonopide aus der jiingeren Trias ostafrikas. N. Jb. Miner. (B), 80,
264-272.

— 1939. Ein kleiner Pseudosuchier und ein Saurischier aus den Ostafrikanischen Mandaschichten. Ibid. 81,
61-69.

kauffman, e. g. and kesling, r. v. 1960. An Upper Cretaceous ammonite bitten by a mosasaur. Contrib.
Mus. of Paleont., Univ. Michigan. 15, 193-248.

kitching, j. w. 1977. The distribution of the Karroo vertebrate fauna. Mem. Bernard Price Institute Pal.,
Witwatersrand Univ. 1, 1-131.

krebs, b. 1976. Thecodontia: Pseudosuchia, 40-120. In kuhn, o. (ed.). Encyclopaedia of Paleoherpetology.
Part 13. Gustav Fischer Verlag, Stuttgart.

nowack, E. 1937. Zur kenntniss der Karru-formation im Ruhuhu-graben (D.O.A.). Neues Jb. Min. Geol.
Paldont. (abt. B), 78, 380-412.

romer, a. s. 1971. The Chanares (Argentina) Triassic reptile fauna. VIII. A fragmentary skull of a large
thecodont, Luperosuchus fractus. Breviora, 373, 1-8.

stockley, g. m. 1932. The geology of the Ruhuhu coalfields, Tanganyika Territory. Q. Jl geol. Soc. Lond. 86,
610-622.

walker, A. d. 1964. Triassic reptiles from the Elgin area: Ornithosuchus and the origin of carnosaurs. Phil.
Trans. R. Soc. Lond. (B), 248, 53-134.

— 1972. New light on the origin of birds and crocodiles. Nature, Lond. 237, 257-263.

A. R. I. CRUICKSHANK

72 Thirlmere Road
Hinckley, Leicestershire
LE10 0PF, UK

Typescript received 12 July 1985

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Palaeontology

VOLUME 29 ■ PART 2

CONTENTS

A revision of Semionotus (Pisces: Semionotidae) from the Triassic
and Jurassic of Europe

AMY R. MCCUNE 213

A new genus of inadunate crinoid with unique stem morphology from
the Ashgill of Sweden

STEPHEN K. DONOVAN 235

Community preservation in Recent shell-gravels, English Channel
RICHARD CARTHEW and DAN BOSENCE 243

Early Eocene insectivores (Mammalia) from the People’s Republic
of Mongolia

D. E. RUSSELL and D. DASHZEVEG 269

The late Triassic reptile Teratosaurus — a rauisuchian, not a dinosaur
MICHAEL J. BENTON 293

New late Palaeozoic Hyolitha (Mollusca) from Oklahoma and Texas,
and their palaeoenvironmental significance
JOHN M. MALINKY, ROYAL H. MAPES and

THOMAS R. BROADHEAD 303

Taxonomy, phytogeny, and variability of Pseudisograptus Beavis

R. A. COOPER and N I YUNAN 313

The first articulated freshwater teleost fish from the Cretaceous of
North America

LANCE GRANDE 365

The nematularium of Pseudodimacograptus scliarenbergi (Lapworth)
and its secretion

CHARLES E. MITCHELL and KAREN J. CARLE 373

Ellisites , an Upper Ordovician heliolitid coral intermediate between
coccoserids and proporids

OWEN A. DIXON, THOMAS E. BOLTON and PAUL COPPER 391

Archosaur predation on an east African Middle Triassic dicynodont
A. R. I. CRUICKSHANK 415

Primed in Great Britain at the University Printing House , Oxford
by David Stanford, Printer to the University

ISSN 0031 0239

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