Amencan Museum
ovitates
PUBLISHED BY THE AMERICAN MUSEUM OF NATURAL HISTORY
CENTRAL PARK WEST AT 7QTH STREET, NEW YORK, N, Y. 10024
NUMBER 2328 JULY 19, 1968
Hinge Grades in the Evolution of
Crassatellacean Bivalves as Revealed
by Permian Genera
By Dona_Lp W. Boyvp! anp Norman D. NEWELL?
ABSTRACT
The origin and affiliation of the conservative bivalve superfamily Crassa-
tellacea Férussac, 1822 (=Astartacea d’Orbigny, 1844), have been uncertain.
Some authors have regarded these mollusks as lucinoids. Others have placed
them with the cyrenoids, or in a separate order of the Heterodonta, the “Astarte-
donta.”
Our discovery of numerous exceptionally well-preserved examples of the
Crassatellacea of Permian age in Wyoming clarifies some problems of the early
history of the group, showing how, by the acquisition of additional hinge teeth
after Permian time, the hinge of living crassatellaceans became modified in sepa-
rate lines from basically lucinoid to a more advanced hinge grade.
Representatives of post-Paleozoic Crassatellidae and Astartidae through con-
vergent evolution resemble one another more closely than do their Paleozoic
ancestors, the new subfamilies Oriocrassatellinae and Astartellinae. Members of
these Paleozoic subfamilies are sufficiently dissimilar to suggest a diphyletic
origin for the Crassatellacea.
The Bernard and Munier-Chalmas hinge formula and its implication of dental
homologies are discussed, and a simplified, more objective hinge notation based
on the Steinmann system is employed.
Two new species, Oriocrassatella elongata and Astartella aueri, are described.
1 Professor of Geology, University of Wyoming, Laramie.
2 Chairman and Curator, Department of Fossil Invertebrates, the American Museum
of Natural History; and Professor of Geology, Columbia University.
2 AMERICAN MUSEUM NOVITATES NO. 2328
Examples of hinge transposition of cardinal and anterior lateral teeth, but not
the posterior laterals, are recorded in both. This partial transposition of hinge
teeth, recorded for the first time in Paleozoic bivalves, indicates that the posterior
laterals are genetically independent of the other hinge teeth.
INTRODUCTION
A systematic search for Permian bivalves in the Rocky Mountains of
the United States has extended over many decades. Following a discov-
ery by Carl C. Branson (1930) of a diversified but poorly preserved
pelecypod assemblage in the Park City (Phosphoria) Formation at Bull
Lake, in the Wind River Mountains of Wyoming, one of the present
authors (Newell) made several exploratory trips to that area in search
of more satisfactory specimens of what appeared to be an unusually
varied assemblage. His interest in this subject stimulated some of his
students, notably A. G. Fischer and K. W. Ciriacks, to make additional
exploration for well-preserved representatives of the Bivalvia in western
Wyoming. Their work was rewarded by only limited success.
Ciriacks did, however, have access to extensive collections obtained
during a large program of field research by the United States Geologi-
cal Survey. Those collections were disappointing because of the imper-
fect preservation and the scarcity of instructive individuals showing
critical morphological details. Ciriacks’ (1963) outstanding research and
publication on the available collections of Permian pelecypods from
Wyoming and Idaho provided a tantalizing glimpse of a distinctive and
varied fauna. Furthermore, he showed that the Park City sequence in
the Wind River Mountains is mainly of early Guadalupian age, that
is, more or less equivalent to the Word, Brushy Canyon, and Cherry
Canyon formations of western Texas pertaining to the zone of advanced
species of Parafusulina.
More recently, Benjamin Weichman, while a graduate student at the
University of Wyoming, discovered exceptionally well-preserved silicified
bivalves of limited diversity in the lower member of the Park City For-
mation along Beaver Creek Canyon, in the southeastern part of the
Wind River Mountains. Boyd and Newell undertook extensive sampling
from this locality, processing the fossils at the University of Wyoming
and at the American Museum of Natural History. The resulting col-
lection of bivalves, now divided between the University of Wyoming at
Laramie, and the American Museum of Natural History, Department
of Fossil Invertebrates, is the most remarkable thus far obtained from
Permian rocks in the Rocky Mountains.
The present paper is the first of several contributions undertaken
1968 BOYD AND NEWELL: HINGE GRADES 3
jointly by us on the systematics of Permian bivalves. Faunal and eco-
logical summaries necessarily must be deferred until the basic taxonomic-
phylogenetic studies are well advanced.
The abbreviations used in this paper for various institutions are:
A.M.N.H., the American Museum of Natural History, specimens catalogued in
the Department of Fossil Invertebrates
A.M.N.H.:F.I., used without the abbreviation “No.” means a fossil locality,
recorded by the Department of Fossil Invertebrates, the American Museum
of Natural History
A.M.N.H.:L.1, the American Museum of Natural History, specimens cata-
logued in the Department of Living Invertebrates
U.L, the University of Indiana, Bloomington
U.W., the University of Wyoming, Laramie
ACKNOWLEDGMENTS
Mr. Benjamin Weichman, who discovered the fossil locality (A.M.N.H.:
F.I. 2010) that has yielded our extraordinary collection, communicated
his find to Boyd. Mr. and Mrs. John Auer, on whose ranch the discov-
ery was made, have shown great interest in our work and have encour-
aged us in many ways. Dr. Heinrich Toots, then a graduate student at
the University of Wyoming, aided in the arduous labor of collecting
the samples, and Mr. G. Robert Adlington of the American Museum of
Natural History prepared the outstanding photographs reproduced
herein. Mrs. Margaret Boyd undertook the sorting of specimens and
the compiling of biometrical data. Mr. and Mrs. Dan Steger of ‘Tampa,
Florida, and Mr. Thomas L. McGinty of Boynton Beach, Florida, con-
tributed juvenile specimens of Hybolophus speciosus (Adams), a common
living Caribbean crassatellid, for comparison with the Permian speci-
mens of Oriocrassatellaa and Dr. A. S. Horowitz, of the University of
Indiana at Bloomington, lent us specimens of Cypricardella subelliptica
Hall. To all these persons we extend our thanks. The studies of Aus-
tralian and Kashmirian examples of Procrassatella by Newell were made
possible by a grant from the National Science Foundation (Grant
B-15567) to the American Museum of Natural History.
THE BEAVER CREEK MATERIAL
The Beaver Creek collection was obtained from a limestone ledge
64 feet above the Tensleep Sandstone in the northeast quarter of sect.
15, T. 30 N., R. 97 W. Approximately 2 tons of limestone was leached
in muriatic acid, yielding predominantly bivalves and very few repre-
sentatives of other groups (brachiopods, echinoderms, trilobites, bryo-
4 AMERICAN MUSEUM NOVITATES NO. 2328
LEFT VALVES
ade
| ‘
Yl... |
0 4 6 8 1012 12+ 0 2 4 6 8 10 12 12+
MEASUREMENT DIN MM.
Fic. 1. Frequency histogram of length of cardinal armature, D, based on
more than 700 specimens of Oriocrassatella elongata, new species, showing closely
similar distribution of the two valves, with a suggestion of several age classes.
Evidently there was very little postmortem sorting of the shells. See also figure
18 for the precise usage of variate D.
zoans, gastropods, nautiloids, and scaphopods). This assemblage suggests
that the bivalve fauna lived under ecological conditions that were in-
compatible with the dominantly brachiopod-bryozoan association so
characteristic of the Phosphoria-Park City formations in western Wyo-
ming. Because these fossils were collected near the eastward transition
from carbonate rocks to redbeds and gypsum (Maughan, 1964), it can
1968 BOYD AND NEWELL: HINGE GRADES 5
be assumed that deposition was at shallow depth near shore and that
the waters may have been hypersaline or variable in salinity. Because
right and left valves of the pelecypod species occur in approximately
equal numbers and in various stages of growth (fig. 1), it is concluded
that there was comparatively little sorting or movement of the material
after death.
The Beaver Creek locality has provided thousands of silicified speci-
mens of several pelecypod species. Unbroken valves are rare, but com-
plete hinge plates are common. Of the several new pelecypod species
in the collection, noteworthy are the crassatellaceans described herein.
It is generally agreed that the superfamily Crassatellacea of the sub-
class Heterodonta embraces two families, the Crassatellidae and the
Astartidae. The pre-Cretaceous record of the Crassatellidae is very poor.
Crassatellids reported in Permian strata of the Americas include only a
single external mold from Greenland (Newell, 1955), two fragmental
specimens from Wyoming (Ciriacks, 1963), and a few unpublished speci-
mens from the Permo-Carboniferous of southern Brazil. Knowledge of
Permian crassatellids has been based largely on Australian (e.g.,
Etheridge, 1907; Dickins, 1956; Newell, 1958) and Russian (Yakovlev,
1928) examples preserved as molds. The rarity of well-preserved speci-
mens in the past has prevented a confident interpretation of hinge
morphology. By contrast, we have assembled and studied more than
700 hinges of the new crassatellid species, from the Beaver Creek lo-
cality, a collection some 10 times greater than all the Permian specimens
thus far reported over the world. The excellent Wyoming material thus
has revealed certain fundamental differences between crassatellids of
the Paleozoic and those of the post-Paleozoic.
The family Astartidae is represented in the Beaver Creek collections
by a new species closely related to Astartella subquadrata Girty, a frequent
component of Permian collections from the southwestern United States.
Our silicified material has provided 268 specimens retaining the hinge.
These reveal certain intriguing contrasts between astartid and crassa-
tellid hinge patterns, and, as with the crassatellids, we find basic dif-
ferences between Paleozoic and post-Paleozoic astartids.
The incentive for a detailed analysis of the hinge provided by our
crassatellaceans has led us to review the conventional heterodont hinge
notation. The current status of heterodont hinge analysis appears to be
one of confusion and inconsistency. The following brief discussion of
the heterodont hinge was deemed necessary, therefore, before the par-
ticular problem of crassatellacean dentition was discussed.
6 AMERICAN MUSEUM NOVITATES NO. 2328
THE HETERODONT PELECYPOD HINGE
HETERODONT HINGE FORMULA OF BERNARD AND MuNIER-CHALMAS
A method of designating homologous bivalve hinge teeth was devised
independently and synthesized late in the nineteenth century by Bernard
and Munier-Chalmas. Their notation has been widely recommended,
but it has not been universally adopted in practice. In many cases their
method of naming teeth is difficult to apply because homologies among
dissimilar bivalves commonly are not readily demonstrable; the homolo-
gous teeth must be recognized and correlated before the notation can
be applied.
According to the original plan of Bernard and Munier-Chalmas
(Bernard, 1895, 1896a, 1896b, 1897, 1898), cardinal teeth were assigned
Arabic numbers and lateral teeth were given Roman numerals. These
categories were numbered from a median position outward (cardinals)
and from a ventral position upward (laterals). Growth studies of the
hinges of various living species indicated to those investigators that a
few primary lamellae along the anterodorsal margin became differen-
tiated during growth into anterior laterals and cardinals in a charac-
teristic manner. Bernard and Munier-Chalmas were not successful,
however, in correlating anterior and posterior lateral teeth, and they
were necessarily vague about the treatment of the posterior laterals.
Cardinal tooth 1 is a modified part of anterior lateral Al; 2, of AII;
and so on. Both 2 and 3 commonly divide to form 2a, 2b, and 3a, 3b,
respectively. On the other hand, tooth 4b, although correlated with
AIV, is not, in our experience, accompanied by 4a; and 5b apparently
does not have a counterpart in 5a. Details of these ontogenetic modi-
fications presumably were empricially determined, but they have never
been well documented and need to be confirmed.
The notation of Bernard and Munier-Chalmas for cardinal eck of
the cyrenoid hinge grade
RV 3a -- 1 -- 3b
LV 2a -— 2b -- 4b
specified three cardinals in each valve, whereas lucinoids characteristi-
cally possess only two
RV 3a - 3b
LV 2 —— 4b
But, if growth series are lacking, how can these teeth be identified?
Casey (1952, p. 123) has shown that a bifid, or chevron-shaped, tooth
2 may be produced in more than one way and that the limbs of the
1968 BOYD AND NEWELL: HINGE GRADES 7
chevron should be given a notation that reflects the origins of the re-
sulting teeth. Such complications suggest that the system of Bernard and
Munier-Chalmas, with its stress on homologies, may be misapplied when
used for bivalve taxa in which ontogeny and phylogeny are poorly
known.
The recognition of homologies and the tracing of phylogenetic trends
in bivalve teeth are complicated by the fact that non-occluding, or
incompletely occluding, ridges and furrows along the hinge plate com-
monly are excluded from consideration in the dental notation by most
investigators. An obsolescent or poorly developed tooth ridge, or the
shell margin itself, commonly is not specified in the dental formula.
Indeed, many students of heterodont bivalves designate as teeth only
those that are completely embraced by a socket, or furrow, of the com-
plementary valve. In this narrow definition, a weakly or incompletely
occluding ridge may not be accepted as a hinge tooth. This is not
only illogical but fails to provide for the recognition of newly appearing
or obsolescent teeth.
Semantic difficulties aside, it is well established that teeth of the
heterodonts are “variable” and that new elements may be added and
old ones lost during evolution. It has not been demonstrated, however,
that these historical events are recapitulatory in ontogenies of living
bivalves, as supposed by Bernard. In fact, it may be that they are rarely
recapitulatory.
SIMPLIFIED PLAN FOR HINGE ILLUSTRATION AND NOTATION
In the present study, an effort is made to find a flexible, objective
method of recording the morphological details of the hinge teeth that
can be readily converted to a modified version of the Bernard system
whenever homologies are secure.
The conventional orientation in illustrating bivalve hinges and the
arrangement of dental formulas are extremely confusing. Furthermore,
the idea that dental homologies in related bivalves can be ascertained
by matching hinge teeth in numerical sequence certainly is not war-
ranted unless supported by independent evidence such as graded growth
series or stratigraphic sequences.
Consequently, we find merit in illustrating matched pairs of valves
(figs. 2A, B, 3B, C, 6A, 10B, D) in a manner that facilitates direct com-
parison with a simplified and objective notation. For use with poorly
understood groups, our proposed method has the merit of being free
from implications of uncertain homologies by the avoidance of speci-
8 AMERICAN MUSEUM NOVITATES NO. 2328
Fic. 2. Hybolophus speciosus (Adams), A.M.N.H. No. 28472, recent, dredged
by T. L. McGinty at 20 fathoms, Gulf of Mexico, near Destin, Florida. Com-
pare with Oriocrassatella elongata, new species (fig. 3B, C). A. Right valve.
B. Left valve. Both X2. C. Right valve. <1.
Abbreviations: C, cardinals; e, elastic-ligament area; L, laterals; r, resilifer.
fication of homologues during preliminary studies. The two valves of
a shell are illustrated beak to beak, with the right valve above the left
valve (fig. 2A-C). Conventionally, the Bernard formula places the left
valve below, and our suggested orientation is a concession to this con-
vention. Thus, the posterior parts of both valves lie on the left. The
notation system, a simplification of that of Steinmann as interpreted
by Dall (1913), has been devised to be directly compared with such
illustrations.
The right-valve hinge is expressed by the upper of two lines of sym-
1968 BOYD AND NEWELL: HINGE GRADES 9
Fic. 3. Oriocrassatella elongata, new species, from A.M.N.H.:F.I. 2010, Grandeur
Member, Park City Formation, Permian, Wyoming. A. Latex impression of
interior of left valve, the holotype, A.M.N.H. No. 28473, showing position of
muscle insertions. We interpret numerous papilli over the umbonal region as
borings of parasites. X 1.5. B. Right valve, A.M.N.H. No. 28475. x2. C. Left
valve, the holotype, A.M.N.H. No. 28473. X 1.5.
Abbreviations: aa, anterior adductor; apr, anterior pedal retractor; C, cardinals;
e, external ligament groove; L, laterals; pa, posterior adductor; pe, pedal ele-
vator; ppr, posterior pedal retractor; r, resilifer; s, septum.
bols, and, in both lines, the symbols are arranged from left to right
to reflect a traverse along the hinge from the posterior extremity to the
10 AMERICAN MUSEUM NOVITATES NO. 2328
anterior extremity. The arabic numeral (1) represents teeth or poten-
tially articular ridges. Inconspicuous or dubious teeth are indicated
between parentheses. A zero (0) represents a space between two teeth
or ridges. Generally, but not invariably, these spaces function as sockets
or grooves. In any case, they indicate the position of an articulating
ridge or prominence on the opposite valve. Vertical lines, discontinuous
in case of doubt, are used to delimit the cardinal from the lateral series.
For the crassatellaceans, the letters r, s, n, and e are added to represent
the position of the resilium, the septum, the nymph, and the elastic
ligament, respectively.
THE CRASSATELLACEAN HINGE
CHARACTERISTICS OF THE HINGE
Bernard’s research on the ontogeny and comparative morphology of
the hinges of bivalve mollusks was cut short by his early death, and,
to our knowledge, his work has not been subsequently brought under
critical review. Essential documentation of his views about dental homol-
ogies among living crassatellaceans is lacking, so we are unable to con-
firm or deny his conclusions. However, we note that Bernard and many
subsequent investigators have recognized certain peculiarities in the
dentition of crassatellaceans. Some authors have placed the superfamily
with the lucinoids, others with the cyrenoids. Davies (1935), following
Bernard (1895) and Lamy (1917), considered the Crassatellacea Férussac,
1822 (=Astartacea d’Orbigny, 1844), to be of lucinoid derivation, super-
ficially assuming a cyrenoid aspect as a result of evolutionary acquisition
of an additional cardinal tooth in the right valve.
Davies (op. cit.) segregated the Crassatellacea and Carditacea known
to him from other lucinoids on the basis of their hinge characteristics,
and Korobkov (1954) applied the ordinal name “Astartedonta” to these
bivalves. Our studies indicate, however, that this segregation would
undesirably dismember the lines usually classed as Astartidae and Cras-
satellidae, and distribute them between two of Korobkov’s orders, the
Lucinodonta and the Astartedonta. Consequently, although we ac-
knowledge the utility of “lucinoids” and “cyrenoids” as grades of hinge
complexity, there is little to commend them as bases for separate taxa.
It appears to us more probable that they represent iterative rather than
phyletic grades of complexity. As is shown below, the characteristics
of ancestral crassatellaceans do, indeed, ally them with primitive luci-
noids. But post-Paleozoic forms achieve a more advanced evolutionary
status superficially similar to, but not quite like, the cyrenoid grade.
1968 BOYD AND NEWELL: HINGE GRADES 11
Furthermore, the hinges of later members of the Crassatellidae and the
Astartidae resemble one another more than they do those of their Pale-
ozoic ancestors—an example, apparently, of evolutionary convergence.
Thus, some doubt is cast on the integrity of the superfamily Crassa-
tellacea as usually constituted.
CRASSATELLID DENTAL FORMULAS
In the notation suggested above, the hinge of Hybolophus speciosus, a
living crassatellid (see fig. 2), can be characterized as follows:
Posterior RV 10 (1)(er10101 1 0 1 anterior
LV 10 1 er 1010] (1)01
Bernard and later students have supposed that the right-valve cardi-
nals correspond to 5b, 3b, and 3a, and the two left-valve cardinals, to
4b and 2. We cannot find convincing documentation in the literature
that this notation is firmly based on studies of ontogenetic develop-
ment, or that these teeth are homologous with those of other hetero-
donts conventionally given the same numerals. Rearranged to correspond
with the above scheme, the Bernard notation reads
RV PIII --- (PI) er 5b —- 3b - 3a AIlI --- AV
LV PIV ---- PII er -- 4b -- 2 —- | (AIT) ---- AIV
There has been little agreement, however, about the lateral teeth.
For example, Darragh (1956a, p. 98) cited only two laterals, AII and
PI, in Eucrassatella, although he mentioned AI and PII (zbid, pp. 100,
102) in comments on certain species of that genus. Authors using the
Bernard system have not specified as lateral teeth all the eight ridges
indicated as such in our interpretation of Hybolophus (above). Lamy
(1917, p. 200) utilized AI, AII, AIII, PI, PIT, and PIV. In several dia-
grams he designated a strong posterior lateral between PII and PIV as
PI. It is not clear whether he so intended, because, in the Bernard sys-
tem, the position between PII and PIV should be occupied by PIII.
There is precedent, however, in one of Bernard’s diagrams (1895, p.
121) for the misplacement of a lateral tooth where he places AII above
AI. We assume that this position was unintentional.
Recent crassatellids (indeed, all the post-Paleozoic crassatellids known
to us) possess more cardinals and laterals than does the Paleozoic Orio-
crassatella (fig. 4). Furthermore, the strong septum that divides the resilium
from the ligament in Oriocrassatella is obscure or lacking in post-Paleo-
zoic crassatellids in which the ligament and the resilium are in contact.
In living crassatellids, as in all the astartids known to us, the antero-
12 AMERICAN MUSEUM NOVITATES NO. 2328
Fic. 4. Hinge features of Ortocrassatella. A. Right valve. B. Left valve.
Abbreviations: C, cardinal tooth; e, position of elastic ligament; L, lateral
tooth; r, resilifer; s, septum.
dorsal margin of the right valves overlaps that of the left. The reverse
situation exists in Oriocrassatella. The homologies of Hybolophus and Orio-
crassatella are not at all evident and will remain uncertain until inter-
mediate forms, if they exist, are discovered.
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14 AMERICAN MUSEUM NOVITATES NO. 2328
In Newell’s 1958 interpretation of the hinge of the tooth of Oriocrassa-
tella, AIl was taken to be the anterodorsal margin of the left valve;
lateral AI and cardinal 3a (not observed) were inferred from sockets of
the left valve. The formula suggested was
Posterior RV PIT] --- esr 3b - 3a Al anterior
LV —-—— PII esr 4b -- 2 — — AII
In the light of the more complete information now at our disposal,
we favor the following as diagrammatically representing the hinge struc-
ture of the Permian genus (fig. 5A, D):
Posterior RV 10 (1); esr 101 1
LV 101 esr(1)010 ;, (1) 01
anterior
ASTARTID DENTAL FORMULAS
Although astartids lack the internal ligament of crassatellids, the
dentition of modern representatives of the two families is similar. We
interpret the hinge of a Recent shell (Astarte castanea; see fig. 6A) as
Posterior RV 10 (1)/ n 101 0 (1) 1 0 1 anterior
LV 101 nQ101 0 (1) 01
Davies (1935, p. 156), following Bernard’s interpretation of the hinge
in the Astartidae, derived the following formula, reversed here for
convenience
Posterior RV PIII --- 5b —- 3b - 3a AI anterior
LV ---- PII -- 4b —- 2 -—- — AII
By contrast, Nicol (1955, p. 157) interpreted the hinge in Astarte as
cyrenoid. He designated the large central tooth on the right valve as
the pivotal tooth 1, and termed the bracketing teeth of the left valve
2b and 2a. He (ibid, fig. 4, p. 157) showed a posterior cardinal on the
right valve which he designated 3b. The lack of an anterior cardinal 3a
in his diagram is perplexing, because the left valve (his fig. 1) shows an
appropriate anterior socket.
In the present study, a survey of Cenozoic astartids in the collections
of the American Museum of Natural History indicates that the shell
shown in figure 6A is characteristic in possessing three cardinal teeth
in the right valve. The anterior cardinal, omitted from Nicol’s diagram,
is recognizable in nearly all right valves examined. The posterior car-
dinal, although commonly well developed, is virtually absent from three
Eocene species examined. Both of these teeth are generally small. In
cases in which one is especially poorly developed, the corresponding
1968 BOYD AND NEWELL: HINGE GRADES 15
socket is more conspicuous than the tooth.
The hinge of the Paleozoic genus Astartella is
Posterior RV 10 (1); n (1) 01 O 1 0 1 anterior
LV 101 n 0 10(1);(0)01
If this is interpreted as lucinoid, workers using Bernard’s notation might
express the cardinal arrangement as
Posterior RV (5b) -- 3b --- anterior
LV ---- 4b —- (2)
It appears that Astarte characteristically has the anterior cardinal in
the right valve, whereas Astartella has the anterior cardinal in the left
valve, as do members of the Myophoriidae and of the Scaphellinidae.
The outer anterior lateral of the right valve extends to the beak, an
unusual and primitive feature in heterodonts.
INTRODUCTION OF NEW TEETH IN THE CRASSATELLACEAN HINGE
The lucinoid hinge grade appears at least as early as the middle
Ordovician (McAlester, 1965), whereas the cyrenoid hinge was rare or
lacking before the Mesozoic. These differences in stratigraphic distri-
bution lend support to the view of Bernard, Davies, and others that
the cyrenoid hinge was derived by elaboration of the lucinoid hinge.
Bernard concluded that the splitting of the pivotal (central and prin-
cipal) cardinal tooth in left valves of lucinoids gave rise to two teeth
separated by a new socket. The latter receives a new pivotal cardinal
tooth of the right valve. If this change has been a phyletic as well as
an ontogenetic innovation, it may have been heralded by a broadening
and bilobation of tooth 2 before actual bifurcation. Bilobation of the
pivotal tooth of the left valve is a characteristic feature of many late
Paleozoic pelecypods (e.g., Schizodus) and suggests a possible pattern in
a trend toward multiplication of hinge teeth.
Bernard, Davies, and others have supposed that the three cardinal
teeth of living crassatellacean right valves correspond to 5b, 3b, and
3a, whereas the two cardinal teeth of left valves were designated as 4b
and 2. We have given thought to Nicol’s (1955) view that the central
cardinal on the right valve may be cyrenoid 1 rather than the lucinoid
3b, and we are unable, at this time, to resolve this problem. The Per-
mian crassatellaceans here under consideration clearly are similar to
lucinoids in possessing two cardinal teeth in each valve, whereas the
post-Paleozoic forms generally have a third tooth, commonly identified
as 5b, at the posterior end of the right-valve series. This tooth is repre-
16 AMERICAN MUSEUM NOVITATES NO. 2328
Fic. 6. A, B. Astarte castanea Say, ALM.N.H.:L.I. Nos. 29370a, 29370b, 29370c,
shallow waters near Atlantic Highlands, New Jersey. Note crenulate cardinal
teeth and inner margin and well-developed socket in left valve for 3a. X2.
C-E. Asiartella vera Hall, A.M.N.H. No. 28506, from A.M.N.H.:F.I. 18, Graford
Shale, Pennsylvanian, near Martin’s Lake, Bridgeport, Texas. C, D. X2.
E. X1.
Abbreviations: C, cardinals; L, laterals; n, nymph.
sented in the Paleozoic in Astartella but not in Ortocrassatella. Although
Astartella has the cardinal just cited, it has only two, not three, cardinals
in the right valve. The pivotal tooth of the Paleozoic forms is perceptibly
bifid in the genus Oriocrassatella. The evolutionary bifurcation of this
tooth and the appearance of a new pivotal tooth, 1, in the opposite
valve conceivably could result in hinge development very similar to
that which characterizes living crassatellaceans.
According to this interpretation, the crassatellaceans would consist of
Paleozoic lucinoids, and post-Paleozoic forms of cyrenoid aspect lacking
one tooth typical of the cyrenoid dentition. This suggestion is perhaps
1968 BOYD AND NEWELL: HINGE GRADES 17
more attractive for the crassatellids than for the astartids, because the
pivotal tooth in Astartella is not bifid.
In any case, the two families require a manipulation of different
teeth, in order to derive for both a cyrenoid post-Paleozoic hinge from
a Paleozoic lucinoid ancestor. The cyrenoid pivotal tooth would origi-
nate within the posterior cardinal socket of the right valve in astartids
but in the anterior cardinal socket in crassatellids. The two primary
astartid teeth of the right valve would then change numbers in transi-
tion from Paleozoic to post-Paleozoic (5b to 3b, and 3b to 3a), whereas
the enumeration of crassatellid cardinal teeth of the right valve (3a and
3b) would remain constant. Finally, the two teeth of the left valve would
originate from a splitting of the posterior cardinal (4b) of Astartella, but
from the anterior cardinal (2) in Oriocrassatella.
Even for crassatellids, the preceding hypothesis is suspect, because both
Paleozoic and post-Paleozoic left valves have only two cardinals. It
recognizes an evolutionary trend toward an increase in the number of
cardinal teeth and suggests that a shift in hinge symmetry is accom-
plished by a splitting of the Paleozoic pivotal tooth of the left valve
to accommodate a new pivotal tooth in the right valve. However, this
interpretation requires the disappearance of a pre-existing tooth, the
left posterior cardinal. In the interest of simplicity, it would appear
more likely that steps in the development of the cyrenoid hinge involved
only the appearance of new teeth rather than contemporaneous appear-
ance and disappearance. In our present state of knowledge, it is more
reasonable to suppose that the two cardinals of the left valve in Orio-
crassatella are homologous with those in modern crassatellids, than that
the posterior one has disappeared while the anterior one evolved into
two. Likewise, although it is possible that the two teeth of Paleozoic
right valves are homologous with the anterior and posterior elements
of the three-toothed post-Paleozoic right valves, it appears more likely
that they are homologous with the anterior and central ones, leaving
the posterior rather than the middle one as a post-Paleozoic innovation.
The preferred latter (but not necessarily correct) solution might be as
follows in the Bernardian notation:
RiGHuT VALVES
Hybolophus PIT - (Pl)e r 5b —-— 3b - 3a ATII - AV
Oriocrassatella PUI - (Pl)e sr ---- 3b - 3a ATI
LEFT VALVES
Hybolophus PIV - PIler — 4b —
Ortocrassatella PIV - PII es r —- (4b) --
_— (All) — AIV
_— (AII) - AIV
NO po
18 AMERICAN MUSEUM NOVITATES NO. 2328
This alternative invites speculation that the posterior tooth in ques-
tion, commonly designated as 5b, developed as a wall related to the
posterior margin of the resilifer. The border of the resilium in Orio-
crassatella is reflected in a few valves by an obscure shelf along the
anterior margin of the resilifer (fig. 5A). This shelf occupies a position
analogous to that of the posterior cardinal in post-Paleozoic specimens.
Cardinal 5b in living species is more variable in size and orientation
than the other cardinals, and the left valves lack a corresponding socket
in some species.
HinGeE TRANSPOSITION IN Oriocrassatella AND Astartella
The phenomenon of hinge transposition involves an exchange of part
or all of the dental elements by the two valves of a pelecypod shell.
Thus teeth normally found in a left valve are found in the right, and
so forth. Popenoe and Findlay (1933) have discussed the situation and
have cited numerous examples.
The present study is the second in which transposed dentition has
been recognized in Paleozoic pelecypods, and the first in which partial
transposition has been recorded in Paleozoic material. Newell (1939)
reported the correlated transposition of cardinals and posterior laterals
in some imperfect valves of Pleurophorus albequus Beede from the Texas
Permian. He noted that in other reported instances of transposition, all
involving Tertiary and Recent heterodonts, the cardinals and anterior
laterals are transposed independently of the posterior laterals. That is,
in cases in which the posterior laterals were transposed, the other teeth
were unchanged, and vice versa. He cited a previous suggestion (Popenoe
and Findlay, 1933) that such incomplete transposition would be under-
standable in view of Bernard’s observation that the heterodont cardinal
and anterior lateral teeth develop from the same lamellae, whereas the
posterior laterals develop from different lamellae. Presumably, the poste-
rior laterals are governed by a separate genetic field from that of the
other hinge teeth. Our present collections support such a hypothesis.
Three left valves of more than 700 specimens of Oriocrassatella elongata
of Permian age from Beaver Creek, Wyoming, are abnormal in posses-
sing a partially transposed dentition. They exhibit the two cardinal
teeth and an anterior lateral tooth typical of right valves. The resilifer,
septum, ligament furrow, and posterior lateral teeth and socket are
identical with those of other left valves of the species (fig. 5B, C).
Weaver (1963) reported the same type of transposition, affecting cardi-
nals and anterior margin, in a left valve of Crassatella collina from the
undifferentiated Sacate-Gaviota Formation of the California Tertiary.
1968 BOYD AND NEWELL: HINGE GRADES 19
Fic. 7. A-C. Cypricardella subelliptica Hall, type species of Cypricardella Hall,
Salem Limestone, Mississippian, Indiana; shown for comparison with Astartella
Hall. A. Left valve, U.I. No. 8130, Salem Limestone, Mississippian, Cleveland
Quarry, sect. 20, T. 7 N., R. 1 W., Monroe County, Indiana. X20. B. Left
valve, A.M.N.H. No. 7641:1, one of Hall’s syntypes, Salem Limestone at Sper-
gen Hill, Indiana, showing close external similarity to Astartella. X2. C. Right
valve. A.M.N.H. No. 7641:2, one of Hall’s syntypes, Salem Limestone at
Sperges Hill, Indiana. X10. D-G. Astartella aueri, new species, from A.M.-
N.H.:F.I. 2010, Grandeur Member, Park City Formation, Permian, Wyoming,
illustrating transposition of hinge teeth. D. Normal left valve, A.M.N.H. No.
28504. 3. E. Transposed left valve, A.M.N.H. No. 28509. x3. F. Normal
right valve, A.M.N.H. No. 28497. <4. G. Transposed right valve, A.M.N.H.
No. 28508. 4.
Abbreviations: C, cardinal teeth; n, nymph.
Darragh (1965b) observed the same phenomenon in two valves in a
collection of 540 Eucrassatella specimens from the Tertiary of south-
eastern Australia.
The Beaver Creek collection of Astartella aueri includes three valves
with the same type of partial transposition described above. In one
mature left valve, the anterior lateral teeth, anterior socket, and pre-
sumably the large cardinal tooth are those of a right valve, whereas
the posterior lateral teeth are normal for a left valve (fig. 7D, E). In
two right valves, the anterior laterals, anterior cardinal tooth, large
socket, and large cardinal are those of a left valve, whereas the posterior
hinge area is normal for a right valve (fig. 7F, G). The three astartid
‘EX “GIG8Z ‘ON “H'N'W'V ‘['€x ‘F1S68 ‘ON “H'N'W'V ‘1 '€X ‘H
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JO} JOYOOS aj}0u ‘Joyos payepnuaio Surmoys ‘/0GZ “ON “H'N'W'V ‘4[e4 YoeT “Dp ‘Surmod ‘ueruog ‘uoneuo0g
AWD ye “equey sinepuriy ‘O10e Ta H'N'W'V Woy ‘sowods mou “anv opyanjsy ‘[-J ‘zx Wog ‘uoTNMUAp
yewuou surmoys ‘Z/T'Z09ZI “ON “H'N'W'V ‘24]e4 148 [euON] ‘gq ‘uoNMUap pasodsuen SuIMmoyUs ‘1/T'ZO9ZI “ON
‘HA NW'Y es 148ry “y ‘sure ‘Sutis0q ‘si9uJ0D psojpooMA ‘suU2I00}sIa[g ‘uosduINg suay aunisp “gq ‘VW “g ‘Oly
20
1968 BOYD AND NEWELL: HINGE GRADES 21
valves with transposed dentition were found in the course of an exami-
nation of 268 Astartella hinges from the Beaver Creek locality. Popenoe
and Findlay (1933) reported the ratio of occurrence of transposition in
astartids as 1/130 for Astarte and 1/3 for Goodallia. The transposition
of the anterior lateral and cardinal dentition in a right valve of Astarte
lens Stimpson is shown in figure 8A. A normal right valve of the same
species is shown in figure 8B.
PrrE-PENNSYLVANIAN CRASSATELLACEANS
The Crassatellidae are characterized in living species by a wholly in-
ternal alivincular ligament in adults, whereas the Astartidae retain the
more primitive, external, opisthodetic, parivincular ligament. Both fam-
ilies may have been in existence in mid-Paleozoic times, since repre-
sentatives have been reported from Mississippian and Devonian rocks.
Although it is not our aim in this paper to undertake a thorough inves-
tigation of the pre-Permian members of these families, some comments
are in order by way of placing the Permian material in perspective.
The name Cypricardella Hall (type C. subelliptica Hall, Salem Lime-
stone, Mississippian, subsequent designation, S. A. Miller, 1889) is
commonly applied to North American and European crassatellacean bi-
valves of Devonian and Mississippian age. Many of the species bear a
close external resemblance to Astartella Hall, the latter name being con-
ventionally used for Pennsylvanian and Permian astartids.!
1The status of the two genera is complicated by the fact that both apparently were
published in 1858, and we have been unable to determine which actually was released first.
It appears, however, that there are adequate morphological grounds for distinguishing
the two on hinge characteristics.
Diagnoses of Cypricardella and the two species C. nucleata and C. subelliptica were pub-
lished in article 1, volume 4, of the Transactions of the Albany Institute. The volume in
which this publication appears covers the work of the Institute for the period 1856-1863.
Although the date 1858 is commonly attributed to article 1, the date of impression of
the whole volume is 1864, and we are unable to confirm an earlier release of the section
containing the publication of Cypricardella.
The date of the first use of the name Astartella Hall is clear. It was described as a
new genus on page 715 of Report on the Geological Survey of the State of Iowa, volume 1,
part 2. Two species of Cypricardella, C. nucleata and C. subelliptica, were described in the
same volume on pages 663-664, but the genus Cypricardella was not described as new in
this publication. In volume 1, part 1, there are three letters of transmittal from James
Hall to the Governor of Iowa. The third and last of these is dated September, 1858. It
is possible, but not probable, that Cypricardella as stemming from the Albany publication
has a few weeks’ or months’ priority over Astartella. If the Iowa publication, on the other
hand, was released before the Albany publication, then both genera would date from
1858, and we are adopting this conclusion.
22 AMERICAN MUSEUM NOVITATES NO. 2328
The hinge characters of Cypricardella have not been well known, and
we have attempted to investigate the type species, C. subelliptica Hall,
with topotypes from the Salem Limestone of Indiana, lent to us by
Dr. Alan Horowitz of the University of Indiana. The shells are quite
small and were prepared mechanically for us by Mr. Frank Lombardi
of the American Museum of Natural History (fig. 7A—C).
The cardinal teeth of the Indiana Cypricardella appear to us as
Posterior RV 0 1 O anterior
LV 101
For comparison, Astartella is
Posterior RV (1) 0 1 O anterior
LV 0 1 0 (1)
and the post-Paleozoic Astarte is
Posterior RV 1 0
LV 01
(1) anterior
0 (1
1 0
1
0
All three genera have a lunule, escutcheon, external opisthodetic liga-
ment, and concentric ornamentation. In all, the left valve overlaps the
right behind the beaks, but the right overlaps the left in front of the
beaks. Thus it is tempting to view the three genera as stages in a phy-
logeny independent of the crassatellid lineage and characterized by the
addition of cardinal teeth in the right valve. Furthermore, the similarity
of the Indiana Cypricardella and Astartella to the Myophoriidae in the
location of the anteriormost cardinal tooth on the left valve is note-
worthy.
Chavan (1952) thought that Cypricardella might be a crassatellid. He
has pointed out to us (personal communication) that C. subelliptica re-
sembles his C. baudeti from Visé, in Belgium, in the possession of a wide
space between the principal cardinal tooth and the ligament nymph.
Interpreting this to be a resilifer, he concludes that Cypricardella pos-
sessed both internal and external ligament elements. If so, the genus
would be allied with the crassatellids, as indicated in his diagnosis of
the hinge of C. baudetz. He recognized (1952, p. 119) two cardinals in
each valve, the anteriormost of these being in the right valve. We have
not recognized the anterior tooth in the Indiana material.
Haffer (1959) has discussed Devonian shells which he referred to
Cypricardella. Although he regarded the genus as an astartid, his diagnosis
of the teeth was similar to Chavan’s in the recognition of an anterior
cardinal on the right valve. He (1959, fig. 17) showed a socket in the
left valve between the anterior cardinal and the margin, whereas in
1968 BOYD AND NEWELL: HINGE GRADES 23
left valves of the Indiana Cypricardella the anterior cardinal is the en-
larged dorsal end of the anterior lateral (fig. 7A).
Another genus of interest in the early history of crassatellaceans is
the Devonian Crassatellopsis of Europe. Beushausen’s (1895) illustrations
suggest cardinals like those of Astartella, with the anteriormost in the
left valve. However, Haffer’s diagrams (1959, fig. 16) indicate three car-
dinals, with the anteriormost on the right valve. Obviously, much more
information is needed on these early forms.
CRASSATELLACEAN SUBFAMILIES
Although evidence at hand resolves neither the basic question of the
phylogenetic relationship between the Astartidae and the Crassatellidae,
nor the problem of recognizing homologous teeth in different genera,
it does show that Paleozoic representatives of these two families differ
in important ways from post-Paleozoic forms. We are emphasizing these
differences by assigning the Paleozoic and post-Paleozoic species to
separate subfamilies. Thus, the Oriocrassatellinae, new subfamily, and
the Crassatellinae, include, respectively, the Paleozoic and the post-
Paleozoic crassatellids, whereas the Astartellinae, new subfamily, and the
Astartidae receive, respectively, the Paleozoic and the post-Paleozoic
astartids.
ORIOCRASSATELLINAE AND CRASSATELLINAE
In order to gain an understanding of the family characteristics of the
Crassatellidae, and to ascertain which features have been subjected to
appreciable evolutionary changes subsequent to Permian time, we have
studied some 26 post-Paleozoic species of the Crassatellidae in the col-
lections at the American Museum of Natural History. We have not en-
deavored to confirm the specific identification or even generic assign-
ments indicated on the museum labels, as we were interested primarily
in general comparisons. The specimens examined include representatives
of Cretaceous, Eocene, Oligocene, Miocene, Pliocene, and Recent age.
The Recent specimens are from Australia, Tasmania, Timor, and the
Gulf of Mexico; all are from low latitudes and warm waters. The fossil
material is from Europe and North America. Useful data on Cenozoic
members of the Crassatellidae also were gleaned from the publications
of Lamy (1917), Darragh (1965a, 1965b), and Boreham (1965).
The 26 post-Permian species have several features in common which
set them apart from those of Permian Oriocrassatella. ‘Their external
shape is variable, but all exhibit a lunule, escutcheon, and a third
posterior cardinal tooth in the right valves; all these are lacking in the
24 AMERICAN MUSEUM NOVITATES NO. 2328
Paleozoic forms. The lamellar ligament in the geologically younger
species has become merged with the resilium as an essentially internal
feature, with the corresponding disappearance of the septa. In most of
the Crassatellinae the posterior cardinal of the right valve diverges at
a low angle from the posterior side of the pivotal tooth near its ventral
end, but in one species it projects anteriorly from that tooth almost
parallel with the valve length. The posterior cardinal tooth in the right
valve has a corresponding socket in the left valve in several Cretaceous
and Eocene species, but this socket was not observed in the younger
species studied. Another feature typical of post-Paleozoic crassatellids
examined is the presence of transverse ridges and grooves (striae) on
the sides of the cardinal teeth.
An easily recognizable and consistent characteristic of the Crassatel-
linae is a lateral socket of the right valve which embraces the antero-
dorsal margin of the left valve. In Oriocrassatella, the anterodorsal margin
of the left valve simply overlaps the margin of the right valve. Many,
but by no means all, of the post-Paleozoic species possess concentric
ridges over the umbonal area or over the entire shell, whereas most of
the Paleozoic species are unornamented.
Several additional features not present in Oriocrassatella are found in
post-Paleozoic crassatellids. The posterior cardinal of the left valve and
the central cardinal of the right valve are inclined anteriorly in Mio-
cene and Recent species studied, whereas in the pre-Miocene forms one
or both of these teeth are inclined posteriorly. The ventral margin in
most of the Cretaceous and Eocene species studied is crenulate, but
crenulation was noted in only one of the post-Eocene species, a recent
form from Ceylon. The inner margin of the valves and the teeth of all
known species of Oriocrassatella are smooth.
In early ontogeny, recent crassatellids appear to have both external
and internal ligament elements, but expansion of the ligament during
growth is inward. Fresh or wet-preserved living crassatellids have not
been available to us, but dry specimens show that the triangular fibrous
resilium is bordered posteriorly by a band of uncalcified lamellar liga-
mental material evidently corresponding to the originally external
lamellar ligament. Although a septum does not separate the two ele-
ments in living forms, the corresponding areas on the hinge plate are
topographically distinct, and the resilifer is outlined as a depression in
the ligamental area (fig. 2). In some, but not all, of the post-Paleozoic
species, as well as in Oriocrassatella, the resilium does not extend to the
ventral margin of the resilifer. The internal ligament somewhat resembles
the internal ligaments of Mactra or Lutraria. However, none of the mem-
1968 BOYD AND NEWELL: HINGE GRADES 25
bers of the Crassatellidae is known to be a deep burrower, and none
is sinupalliate. Muscle scars, both adductor and pedal, are similar in
position in all the crassatellids that we have examined (fig. 9). They
consist of subequal adductors, one posterior and one anterior pedal
retractor, and one pedal elevator.
ASTARTELLINAE AND ASTARTINAE
A survey was made by us of 16 Holocene species of Astarte from var-
ious localities of the British Isles, the Mediterranean, and the east and
west coasts of North America in order to gain an understanding of
modern representatives of the Astartinae. In addition, 13 Tertiary and
Fic. 9. Musculature in’ Oriocrassatella elongata, new species, as interpreted on
latex internal mold of a right valve.
Abbreviations: aa, anterior adductor; apr, anterior pedal retractor; pa, posterior
adductor; pe, pedal elevator; ppr, posterior pedal retractor. Approximately X 2.
one Pleistocene species were examined. They represent localities in Eu-
rope and the east and Gulf coasts of North America. Specimens of five
Mesozoic species were studied, although their hinges are too poorly pre-
served to permit an unequivocal determination of the presence or ab-
sence of minor teeth.
The right valves of post-Paleozoic species (Astartinae) are character-
ized by three cardinals (fig. 6A), whereas those of Paleozoic species
(Astartellinae) have two (fig. 6C). In Astartella and, we believe, in the
topotype material of Cypricardella subelliptica (fig. 7A), the anterior car-
dinal tooth is in the left valve at the anterior margin of the hinge plate.
In Astartella this tooth is formed, rather inconspicuously, by an inward
thickening of the valve edge (fig. 10D). A cardinal tooth is not present
in this position in the Astartinae. In that group, the anterior cardinal
is in the right valve, and its socket intervenes between the valve edge
and the front cardinal of the left valve (fig. 6A).
26 AMERICAN MUSEUM NOVITATES NO. 2328
Fic. 10. Astartella auert, new species, from A.M.N.H.:F.I. 2010, Grandeur
Member, Park City Formation, Permian, Wyoming. A. Beak view of articulated
shell, A.M.N.H. No. 28483, showing lunule, escutcheon, and ligament cleft;
right valve overlaps anteriorly and left valve overlaps posteriorly. x4. B.
Right valve, A.M.N.H. No. 28482. 3. C. Left valve, A.M.N.H. No. 28486,
photographed by transmitted light; the radial dark lines commonly are not
visible on the surface. <3. D. Left valve, the holotype, A.M.N.H. No. 28479.
x 3.
Abbreviations: C, cardinal teeth; L, lateral teeth; n, nymph.
Dr. K. Nakazawa, of the University of Kyoto, Japan, has pointed
out to us that this difference would be achieved if the anterodorsal
marginal ridge of the left valve of Astartella migrated upward during
evolution while the anterior cardinal lengthened ventrally. Support for
this idea is found in the juvenile valve of a living species of Astarte
figured by Haffer (1959, pl. 12, fig. 9). It appears to recapitulate the
adult condition of Astartella in regard to the relationship of the anterior
lateral and the anterior cardinal on the left valve. It is interesting to
note that, if the postulated evolutionary modification is valid, the outer
anterior lateral tooth on the left valve in the Astartinae is not homol-
ogous with that in the Astartellinae.
Two minor shell features known in both the Astartellinae and the
Astartinae appear to be more frequent in the latter group. Minute
crenulations on the inner ventral valve margin are present in the ma-
1968 BOYD AND NEWELL: HINGE GRADES 27
jority of Tertiary species and in about half of the Holocene species
examined. One collection of modern specimens of Astarte castanea in-
cludes some valves with crenulations and some without. Prominent
striations are common on the sides of the major cardinal teeth and
sockets in Tertiary species studied and are somewhat less prominent in
Holocene examples.
Both subfamilies have external, opisthodetic ligaments reflected by
nymphs and adjacent narrow but sharply defined ligament grooves.
EVOLUTIONARY CONVERGENCE OF CRASSATELLIDAE
AND ASTARTIDAE
The Beaver Creek Permian collection has provided the necessary
quantity and quality of specimens for an ample understanding of the
stage of evolution of Permian crassatellid and astartid hinges. The
Astartidae and the Crassatellidae are represented by Astartella and Orio-
crassatella, both of which probably lie in the lines of evolution culminat-
ing in living representatives of these families.
From the evidence cited above, it appears that hinge features of the
two families converged after the Permian period. In fact, if only the
Paleozoic record were available for consideration, the two families prob-
ably would never have been combined in the same superfamily. Astartella
differs from Ortocrassatella mm lacking an internal ligament and in pos-
sessing a lunule and escutcheon, in the overlap of the right valve on
the left in front of the beaks, and the fact that the anteriormost car-
dinal is borne by the left valve.
The hinge of Oriocrassatella (figs. 3B, C, 4, 5A, D) may be diagrammed
as
Posterior RV 1 O (1)
LV 101
esr 101 1
esr(1)010; (1) 01
anterior
whereas the hinge of Astartella (fig. 6C, D) is
Posterior RV. 10 (1)[n (1) 01 0
LV101 /|n 0 10()
1 O 1 anterior
(1) 01
Our impression of the post-Paleozoic record of the two families is
based largely on Tertiary and Recent collections. However, we also
have examined excellent Cretaceous crassatellids as well as some in-
adequate Jurassic and Cretaceous astartids. The post-Paleozoic specimens
of both families possess lunule and escutcheon, three cardinal teeth in
the right valve, and two cardinals in the left; the anteriormost cardinal
is borne by the right valve, and the right valve overlaps the left in front
28 AMERICAN MUSEUM NOVITATES NO. 2328
of the beaks. The increased similarity of the hinges among the post-
Paleozoic astartids and crassatellids is due mainly to the addition of
many features in the crassatellids, whereas the main change in astartid
hinge character was the addition of an anterior cardinal tooth on the
right valve and a corresponding socket on the left valve. The astartids
remained constant in ligament character, whereas the post-Paleozoic
crassatellids lost the distinctive septum which separated the elastic and
compressional ligament parts. Both the astartids and crassatellids added
teeth during their evolution, producing modern representatives which dis-
play dentition not readily assignable to either the lucinoid or the cyre-
noid heterodont hinges, the “astartedont” dentition. For convenience
the formulas of Hybolophus and Astarte are repeated here
Hybolophus
Posterior RV__1 ‘O (1) erlO101 1 0 1 anterior
LV 101 er 1010 (1) 0 1
Astarte
Posterior RV 10(1) | n 101 0 (1) 1 0 1 anterior
LV 101 n0101 01) {| 9!
TAXONOMY
SUPERFAMILY CRASSATELLACEA FERUSSAC, 1822
FAMILY CRASSATELLIDAE FERUSSAC, 1822
ORIOCRASSATELLINAE BOYD AND NEWELL, NEW SUBFAMILY
Diacnosis: Extinct Crassatellidae differing from Crassatellinae in ab-
sence of lunule and escutcheon, in possessing strong septate nymphs
that intervene between resilium and parivincular (external), opisthodetic
elastic ligament, in having only two cardinal teeth in each valve, with
posteriormost cardinal in left valve, and in overlap of left valve on
right valve in front of beaks.
HincE ForMuLa:
Posterior RV___1 ‘O (1) esr 101 1 anterior
LV 101 esr(1)010 | (1) 01
Rance: Mississippian-Permian, cosmopolitan.
GENUS ORIOCRASSATELLA ETHERIDGE, 1907
Type Species: Oriocrassatella stokesi Etheridge, 1907, monotypic.
SupyectivE| Synonymy: Procrassatella Yakovlev, 1928; type species,
Schizodus planus Golowkinsky, 1868, monotypic.
Diacnosis: Lenticular, ovoid, or elongate, with obliquely truncate
‘(9G61) suppor ;
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30 AMERICAN MUSEUM NOVITATES NO. 2328
posterior margin, pedal and siphonal margins closed, beaks orthogyre
to prosogyre; resilium (as inferred from growth lines) appreciably above
ventral margin of resilifer, each half covered apically by a convex deck;
arrangement and relative prominence of teeth as indicated in subfamily
formula; left anterior (pivotal) cardinal tooth more or less bifid; left
posterior cardinal bladelike, or obsolescent, forming anterior margin of
resilium and commonly reflected by corresponding furrow upon or be-
hind posterior cardinal of right valve.
Rance: Mississippian-Permian, cosmopolitan. ‘Table 1 shows the rela-
tive stratigraphic positions of species as interpreted from the literature.
We have relied mainly on Dickins’ (1963) correlation of Australian and
Russian stages.
Discussion: When Etheridge (1907) created the genus Oriocrassatella
for Australian Permian shells, only imperfect right valves were avail-
able for study. Although he properly rejected the possibility that the
resilifer might be a dental socket, it remained for Yakovlev, in 1928, to
recognize that a septum separates a dorsal ligament groove from a tri-
angular resilifer. These observations were made on late Permian (Ka-
zanian) forms from the Russian platform. Etheridge had mistaken the
septum of his specimens for a cardinal tooth, and he speculated that
the furrow behind it might be a socket. He concluded that Oriocrassatella
lacked lateral teeth, whereas Yakovlev recognized lateral teeth in his
material of Procrassatella which was more complete and better preserved
than the Australian specimens of Oriocrassatella. Noting apparent differ-
ences in hinge features in the Russian and Australian specimens,
Yakovlev proposed a new genus, Procrassatella, for the former.
Dickins (1956) emended the diagnosis of Oriocrassatella, calling atten-
tion to a posterior lateral tooth in newly collected Australian material
as well as a septum separating the ligament furrow from the resilifer.
After studying good specimens of the type species of both Procrassatella
and Oriocrassatella, Newell (1958) concluded that the Russian and Aus-
tralian Permian crassatellids are too similar to be placed in separate
genera. Consequently he regarded Procrassatella as a junior synonym of
Orwocrassatella—a conclusion that is sustained here.
Oriocrassatella elongata Boyd and Newell, new species
Figures 1, 3, 5, 9, 11-21
Diacnosis: Elongate, on average about 1.7 times as long as high;
ventral profile approximating equiangular spiral, with greatest convexity
at anterior extremity; dorsal profile concave on both sides of beak ex-
cept in juveniles, in which margins nearly straight, forming obtuse angle
1968 BOYD AND NEWELL: HINGE GRADES 31
at beak (figs. 11, 12); profile of posterior part of valve commonly ob-
liquely truncate; surface with rounded siphonal ridge from umbo to
posterior extremity of valve; ornamentation lacking; irregular growth
varices prominent on peripheral parts of large valves; without pedal or
siphonal gape; very short and narrow gape into ligament furrow behind
beaks of articulated shell (fig. 13E).
Dental formula as given in discussion of subfamily Oriocrassatellinae.
eore
9 Tea
er eal
Rie tll
aN
Fic. 11. Oriocrassatella elongata, new species, from A.M.N.H.:F.I. 2010, Gran-
deur Member, Park City Formation, Permian, Wyoming. A. Two views of the
holotype, A.M.N.H. No. 28473, a left valve. B-F. Growth series of left valves.
B. A.M.N.H. No. 28518. C. A.M.N.H. No. 28491. D. A.M.N.H. No. 28477.
E. A.M.N.H. No. 28490. F. A.M.N.H. No. 28489. All xX 1.
Left anterior cardinal sulcate and slightly bifid, projecting well beyond
plane of commissure (figs. 5D, 13B); left posterior cardinal obsolescent,
bladelike, and probably not preserved to full height in most specimens,
extending slightly beyond plane of commissure in some specimens; right
posterior cardinal (fig. 5A) narrow, and right anterior cardinal forming
low, rounded ridge along anterior border of major socket.
In each valve, resilifer and cardinal teeth situated on ventrally pro-
jecting hinge plate, except for right anterior cardinal which rests on re-
entrant at anterior extremity of hinge plate; resilifer separated from
narrow ligament furrow by sharply defined but slender septum which
32 AMERICAN MUSEUM NOVITATES NO. 2328
Fic. 12. Ortocrassatella elongata, new species, from A.M.N.H.:F.I. 2010, Gran-
deur Member, Park City Formation, Permian, Wyoming. A. Two views of a
right valve, ALM.N.H. No. 28517. B-F. Growth series of right valves. B. A.M.-
N.H. No. 28481. C. A.M.N.H. No. 28475. D. A.M.N.H. No. 28487. E. A.M.-
N.H. No. 28488. F. A.M.N.H. No. 28476. All x1.
originates apically in a vestigial nymph (fig. 13C-—E) forming posterior
wall of resilifer; anterior border of resilifer in right valves formed by
posterior cardinal (fig. 5A). Anterior edge of resilifer in left valves de-
limited by posterior cardinal tooth; arched cover, or deck, over apex
of resilifer in each valve connecting proximal ends of septum and
adjacent cardinal tooth (fig. 5A, D); ligament furrow and posterior
lateral socket of both valves separated by broad, low rise, and axially
aligned parallel with posterodorsal margin.
Posterior and anterior adductor scars below distal ends of lateral
teeth; anterior scar somewhat higher than long, whereas larger posterior
scar slightly elongate; small, deep, pedal retractor scar adjacent to
posterodorsal margin of anterior adductor scar; umbonal pedal elevator
scar, just anterior to apex of umbonal cavity beneath large cardinal in
left valve (fig. 3A) and beneath corresponding socket in right valve,
varying in shape and clarity (fig. 9); pallial line, lacking sinus, faintly
1968 BOYD AND NEWELL: HINGE GRADES 33
Fic. 13. Oriocrassatella elongata, new species, from A.M.N.H.:F.I. 2010, Gran-
deur Member, Park City Formation, Permian, Wyoming. A. Right valve,
A.M.N.H. No. 28481, showing prominent cardinal tooth; this is not the mate to
B. B. Left valve, the holotype, A.LM.N.H. No. 28473, showing prominent car-
dinal tooth. Both X1. C-E. Articulated specimen, A.M.N.H. No. 28480.
C. Posterior aspect. D. Dorsal aspect. Both <1. E. External ligament region;
nymphs (n) are visible within lanceolate ligament opening (e), <3.
defined in most valves and sharply defined in few; larger valves (e.g.,
greater than 20 mm. in height) thickened in anteroventral area.
VariaTIon: More than 700 silicified specimens, about evenly divided
between left and right valves, were studied. Most specimens consist only
AMERICAN MUSEUM NOVITATES NO. 2328
TABLE 2
MEASUREMENTS (IN MILLIMETERS) OF RIGHT VALVEs OF Ortocrassatella elongata,
New SPECIES
(See fig. 7 for indication of variates C and D.)
Length Height Convexity Cc D
60 31 13 2.8 7.7
58 30 13 4.2 11.4
58 30 13 3.7 9.3
56 28 15 3.9 10.2
55 29 14 3.4 10.9
53 26 12 2.3 7.7
51 30 11 2.7 9.3
51 27 12 3.1 7.6
51 27 11 3.2 8.6
51 26 11 2.9 8.1
51 26 11 2.2 7.4
49 26 11 2.3 7.8
48 25 10 pas 6.8
44 25 10 2.1 7.5
43 26 9 3.0 7.2
41 21 8 1.7 5.1
40 24 9 1.9 7.4
40 21 7 1.5 5.3
38 23 8 1.7 59
38 21 11 1.3 6.5
37 25 8 2.3 6.7
33 20 7 1.3 9.3
29 17 5 1.0 4.9
28 16 6 0.5 3.8
27 16 6 1.0 3.3
26 16 5 1.0 4.0
25 15 6 0.8 3.7
25 15 5 0.9 3.5
24 15 5 1.0 3.6
24 14 6 1.1 3.2
24 14 5 1.0 3.5
23 15 5 0.9 3.5
23 14 5 0.9 2.8
23 14 5 0.8 3.3
23 13 5 0.8 Suid
23 13 5 0.8 3.0
23 13 4 0.7 3.2
22 13 5 0.6 3.1
22 13 4 0.9 3.3
21 14 5 0.9 3.6
21 12 5 0.6 2.9
20 14 4 0.6 3.1
1968 BOYD AND NEWELL: HINGE GRADES 35
TABLE 2—(Continued )
Length Height Convexity Cc D
20 13 4 0.9 2.6
18 12 4 0.7 3.0
18 12 4 0.7 2.8
18 11 4 0.9 3.0
17 11 4 0.7 2.4
15 11 4 0.8 2.6
12 8 2 0.4 1.8
of the sturdy hinge plate; approximately 20 specimens of each valve
are essentially complete.
Measurements of the length, height, and convexity were made on all
valves possible (figs. 15-17; tables 2, 3). The length and height were
measured by placing the specimen on graph paper and reading the
appropriate intervals to the nearest millimeter. The dorsal extremity
was defined by the profile of the umbones. The measure of com-
plexity from the plane of commissure was obtained with calipers after
the valve convex was placed surface upward on a table. The interval
measured was the maximum distance between the plane of commis-
sure and the valve exterior, measured normal to the plane of com-
missure. Because the cardinal teeth of the right valve do not project
significantly beyond the plane of commissure, the entire right valve was
allowed to rest on the table. However, left valves were placed so that
the anterior cardinal, a prominent projection in large valves, projected
beyond the edge of the table and did not influence the measurement.
To determine the variability in the concavity of the posterodorsal
shell profile, measurement C was made (figs. 18, 19). C is the greatest
distance between the arc of the valve margin and a tangent drawn be-
tween the umbo and the posterodorsal extremity.
To determine the size distribution in the collection, measurement D
was selected, as illustrated in figure 18. In right valves, this is the recti-
linear distance along the hinge plate between the septum and the pos-
terior distal corner of the anterior cardinal. On left valves, it is the
rectilinear distance along the edge of the hinge plate between the septum
and the anterior distal corner of the anterior cardinal. Dimension D
was chosen because it can be measured on nearly every identifiable
specimen in the collection (fig. 1). The observed range in D was 1.6
mm. to 12.0 mm. in right valves and 1.2 mm. to 13.1 mm. in left valves.
The utility of D as an index of size is shown by a plot of D against
AMERICAN MUSEUM NOVITATES NO. 2328
TABLE 3
MEASUREMENTS (IN MILLILETERS) OF LEFT VALVES OF Ontocrassatella elongata,
New SPECIES
(See fig. 7 for indication of variates C and D.)
Length Height Convexity Cc D
66 35 13 2.7 12.1
66 35 13 2.5 10.0
58 30 12 2.4 9.9
58 29 12 2.4 10.4
56 28 10 2.1 9.4
55 30 11 2.1 9.4
55 30 11 2.1 9.1
34 30 11 2.7 9.5
53 29 12 2.1 10.3
53 28 12 1.3 7.8
53 28 10 2.0 9.4
52 28 9 1.9 8.2
52 26 9 1.7 8.6
51 27 9 1.6 9.6
49 27 8 1.6 7.8
46 28 9 2.3 8.1
46 26 9 1.2 7.7
46 26 8 1.5 8.1
44 23 8 1.1 6.3
44 23 8 0.8 6.8
43 24 8 0.9 7.5
39 22 7 0.4 6.3
39 21 5 1.2 5.8
37 20 6 0.8 6.1
34 21 6 1.1 6.0
33 20 6 0.7 5.3
33 19 6 0.6 5.4
32 18 5 0.5 5.5
31 19 6 0.9 5.0
30 19 6 0.5 5.1
29 18 6 0.7 4.7
27 15 5 0.5 4,2
26 16 5 0.6 3.9
26 16 4 0.4 3.8
26 15 5 0.4 3.9
25 16 4 0.5 3.6
25 15 ) 0.8 4.1
23 14 5 0.4 3.7
23 14 4 0.6 3.8
22 14 4 0.4 3.8
22 13 4 0.6 3.8
21 13 5 0.4 3.3
1968 BOYD AND NEWELL: HINGE GRADES 37
TABLE 3—(Continued )
Length Height Convexity Cc D
20 12 4 0.1 3.2
19 13 4 0.3 3.1
19 12 4 0.3 3.1
19 12 3 0.4 3.0
17 11 3 0.3 2.6
16 10 3 0.1 2.5
14 10 2 0.2 1.9
the length in complete valves (fig. 20). Nearly the same pattern was
obtained when D was plotted against the height or convexity.
To express the position of the beak along the length of a valve, the
partial length, PL, parallel to the shell length between the anterior ex-
tremity and the beak was measured on complete valves (figs. 18, 21).
One aspect of shape variability difficult to measure is the cross profile
of the posterior part of a valve. This profile, although typically sub-
angular, varies from arcuate to angular (fig. 13C-E).
Growth lines are prominent on large valves. The finest lines distin-
guishable average 0.1 mm. between crests. More prominent varices oc-
cur on peripheral parts of many large valves and are irregularly spaced
on a single valve. For example, one valve exhibits seven such major
growth lamellae, spaced as close as 1.5 mm. and as far apart as 7.1
mm. These marks represent changes in the rate of expansion of the valve
margin, and they coincide with changes in the spiral angle of the sur-
face profile. They are separated by sets of laminae representing an ex-
pansion of the valve convexity accompanied by relatively little increase
in height and length. Major growth interruptions are especially prom-
inent on peripheral parts of large valves, in which the successive margins
of the shell cross the siphonal ridge. In such cases, the outer part of a
lamina may not be in contact with the adjacent younger lamina. Several
valves of similar size were compared in regard to the spacing and num-
ber of prominent growth lines, but no correlation was recognized. Con-
sequently, growth interruptions may not be related to regular cycles.
Some variation of features of the hinge is apparent but is not extreme.
One variable is the degree of furrowing of the large cardinal in the left
valve. At most, the sulcus of the ventral part of the tooth produces a
slightly bifid aspect. Australian specimens of the genus also have been
described as having a bifid anterior cardinal in the left valve (Dickins,
1956, p. 33; 1961, p. 125). This tooth also varies in inclination, best
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1968 BOYD AND NEWELL: HINGE GRADES 39
507 Height mm.
40 x
°
HR x °
e
x
x KR
a
3 oO ® eo e
e
e ee
ese
x e
eee
e
e
e oe
20
Length mm.
20 40 60 80
0
Fic. 15. Height/length variation in three species of Oriocrassatella. Solid
circles: Oriocrassatella elongata, new species. Open circles: Oriocrassatella plana
(Golowkinsky). Crosses: Oriocrassatella stokest Etheridge. Data on O. plana and
O. stokest are from published tables and from measurements on latex replicas
and published illustrations. For measurements of O. elongata, see tables 2 and 3.
expressed in terms of the position of the posteroventral corner of the
tooth relative to the beak. In this sense, the corner of the tooth varies in
position from anterior to the beak, directly beneath the beak, or posterior
to the beak. In small valves, this point is most commonly anterior or
ventral. Examples of all three conditions are found among larger valves.
The right posterior cardinal varies both in thickness and in inclina-
tion relative to the beak. The ventral end of this bladelike tooth ranges
Convexity mm.
20
10
Length mm.
10 30 50 70
Fic. 16. Convexity/length variation of left valves of Oriocrassatella elongata,
new species. Data are in table 3.
40 AMERICAN MUSEUM NOVITATES NO. 2328
e
Convexity mm,
15
e
eo e
eoee
Frequency
1-3 @ eeeee @
4-6 @
10 7-10@ ®O@e cece
ee e@eece
©ece@e@ee
e20@@ ©
ee@@eoe
5 ee@@eece eco
OOOece
eoo0e @
eoee
e
Height mm.
10 20 30 40
Fic. 17. Convexity/height variation in 181 left valves of Ortocrassatella
elongata, new species. Measurements were rounded to the nearest millimeter.
from anterior, directly below, or slightly posterior to the beak. The pos-
terior inclination is uncommon in small, but common in large, valves.
The upper end of the septum is commonly expanded in varying de-
grees at the expense of the ligament furrow, which narrows correspond-
ingly (fig. 5A, D).
The relative lengths of the resilifer and the left anterior cardinal in-
fluence the configuration and orientation of the ventral margin of the
shelflike hinge plate. The free margin varies from straight to irregularly
convex, and its orientation varies with growth (figs. 11, 12). The large
cardinal tends to lengthen faster in early growth than does the resilifer,
so smaller valves (e.g., with height less than 20 mm.) have the ventral
margin of the shelf inclined anteriorly. In later growth stages, the ven-
1968 BOYD AND NEWELL: HINGE GRADES 41
Fic. 18. Diagram of Oriocrassatella elongata, new species, indicating principal
variates used for linear measurements.
Abbreviations: C, convexity of posterodorsal profile; D, arbitrary measure of
cardinal armature; H, height; L, length; PL, anterior partial length.
tral expansion of the resilifer proceeds faster than the lengthening of
the large cardinal, causing the ventral margin of the hinge plate to be-
come parallel to valve length and, in some cases, to be convex outward
below the resilifer.
Comparisons: Of the several described species of Oriocrassatella, O.
elongata, new species, is most similar to O. plana (Golowkinsky) from the
31C mm.
0
Fic. 19. Ratio of variate C to length in left valves of Oriocrassatella elongata,
new species. Data are in table 3; for indication of C, see figure 18.
42 AMERICAN MUSEUM NOVITATES NO. 2328
127, D mm :
8 teat
e “8 :
4 rT | "3.
oe
Length mm.
20 40 60
Fic. 20. Ratio of variate D to length in left valves of Oriocrassatella elongata,
new species. Data are in table 3; for indication of D, see figure 18.
Russian Kazanian. The hinge features are notably similar, but O. elongata
differs in its greater relative length of large valves (1.8/1 versus about
1.6/1), in having a marked concavity of the posterodorsal profile, and
in having greater prominence of the beaks which are situated slightly
closer to the anterior margin than in other species (figs. 15, 21). Orio-
crassatella plana was assigned to Schizodus by its author (Golowkinsky,
1868), and Yakovlev (1928) used it as the type species for Procrassatella.
Only one specimen outside Russia, an external mold of a right valve
from Greenland, has been referred to the species (Newell, 1955).
Oriocrassatella elongata differs in the same respects noted above from
the Australian mid-Permian and early Permian O. stokesi and O. queens-
landica, and from Reed’s (1932) early Permian O. lapidaria, O. brenensis,
and O. intermedia from Kashmir. The specimen of O. stokesi illustrated by
Newell (1958, fig. 2) has both the septum and the ligament furrow
notably wider than the corresponding features on O. elongata, whereas
O. queenslandica is distinguished by an exceptionally thick septum (Dickins,
1961). Reed’s illustrations of the Kashmir species are not adequate for
a comparison of hinge features, but photographs taken by Newell of
1968 BOYD AND NEWELL: HINGE GRADES 43
257 Anterior Partial Length mm. == 00 ies
x :
x
xx
20 x x
x x x 8 °
x e e
08 © eee
x e e@ e006 606 e
15 °o exe
eo bd
° °
ee °
e ° ®
10 g
ee 0°
@oe
bar
5
Length mm.
20 40 60 80
Fic. 21. Comparison of the placement of the beaks in three species of Orio-
crassatella. Solid circles: Oriocrassatella elongata, new species. Open circles: Orio-
crassatella plana (Golowkinsky). Crosses: Oriocrassatella stokest Etheridge. Data
on Q. plana and O. stokesi are from published tables and from measurements
on latex replicas and published illustrations. For measurements on 0. elongata,
see tables 2 and 3. Anterior partial length is the dimension PL indicated in
figure 18. Measurements were rounded to the nearest millimeter.
rubber casts of some of Reed’s specimens have been examined. The cast
from the specimen illustrated by Reed (1932, pl. 7, fig. 1) shows the
right posterior cardinal not sharply separated from the anterior one.
The septum is more robust and the resilifer is narrower than in O. elongata.
Rubber casts from specimens of Oriocrassatella intermedia (Reed) illustrated
in figures 3 and 4 of his plate 7 (Reed, ibid.) show several differences
in comparison with O. elongata. The Kashmir specimens have a narrower
left anterior cardinal, a wider right posterior cardinal, a more bladelike
right anterior cardinal, and a more robust septum, than in O. elongata.
Ortocrassatella compressa Maxwell, another Australian species of upper
Carboniferous and earliest Permian age, is characterized by slight shell
biconvexity and by strong concentric lamellae. It was described (Max-
well, 1964, p. 13) as having only one cardinal tooth on each valve, but
illustrations suggest that the species is based on imperfect molds, and
the details of the hinge may not be fully known.
Occurrence: A single right valve figured by Ciriacks (1963, pl. 12, figs.
1-3) is the only Permian crassatellid cited in the literature from the con-
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44
1968 BOYD AND NEWELL: HINGE GRADES 45
tinental Americas prior to the present study. It was confidently referred
to O. elongata. Ciriacks listed the specimen as from the Grandeur Member
of the Park City Formation at Willow Creek, Wyoming. This locality
is only a few miles north of Beaver Creek, where the present collection
was obtained from the upper part of the Grandeur Member. The strati-
graphic placement of our collection (A.M.N.H.:F.I. 2010) was made for
us in the field by Mr. Edwin K. Maughan of the United States Geo-
logical Survey, an authority on the stratigraphy of the Park City For-
mation.
CATALOGUED SPECIMENS: Holotype, A.M.N.H. No. 28473; topotypes,
A.M.N.H. Nos. 28474-28478, 28480, 28481, 28484, 28485, 28487-
28491, 28516-28518, and U.W. Nos. A1582-A1585.
FAMILY ASTARTIDAE D’ORBIGNY, 1844
ASTARTELLINAE BOYD AND NEWELL, NEW SUBFAMILY
Diacnosis: Extinct Astartidae differing from Astartinae in having
only two cardinal teeth in each valve and in having anteriormost car-
dinal on left valve.
DENTAL FORMULA:
Posterior RV
1 0 (1)
Lv 101
Rance: Devonian? Mississippian to Upper Permian, cosmopolitan.
ASTARTELLA HALL, 1858
Type Species: Astartella vera Hall, 1858, monotypic.
Astartella aueri Boyd and Newell, new species
Figures 7D-G, 8C-J, 10, 22-24
Description: Laterally compressed shells, with beaks prominent and
prosogyre; lunule and escutcheon prominent, essentially unornamented;
beak near valve apex, not incurved; escutcheon steepening greatly to-
ward beak, its anterior part apparently an extension of hinge plate;
dorsal margin strongly concave in front of beaks and gently convex be-
hind beaks; anterior and posterior extremities coinciding with points
where posterodorsal and anterodorsal arcs intersect semicircular lower
margin; ornamentation consisting of concentric ridges, with finer con-
centric lines in troughs; ridges of left valve crossing escutcheon border
before dying out, ridges of right valve terminating abruptly at border,
with situation reversed on lunule (fig. 10A); arrangement and relative
46 AMERICAN MUSEUM NOVITATES NO. 2328
TABLE 4
MEASUREMENTS (IN MILLIMETERS) OF Ricut VALVEs oF Astartella aueri,
NEw SPECIES
(Specimens were selected from a larger size-graded series by means of a table of
random numbers.)
Length Height Convexity
15.2 14.2 4.9
14.3 13.3 4.0
14.1 12.9 3.4
13.8 12.5 3.3
13.7 12.7 4.0
12.7 11.8 3.8
12.7 11.8 3.7
12.7 11.8 3.2
10.7 9.3 2.6
9.8 8.6 1.9
8.8 7.8 ost
8.8 7.3 2.1
8.6 7.5 2.1
8.4 7.5 2.0
8.3 8.1 2.1
7.4 6.6 2.0
6.9 6.2 1.8
6.9 6.0 2.0
6.4 5.6 1.8
6.4 5.6 1.6
5.8 4.5 1.5
5.4 4.7 1.7
5.3 4.7 1.4
4.4 3.9 1.2
4.1 3.8 1.1
prominence of teeth as indicated in subfamily formula; anterodorsal
margin of left valve serving as lateral tooth, fitting into socket on right
valve, posterodorsal margin of right valve received by socket on left
valve; two cardinal teeth on left valve; left anterior cardinal formed by
inward thickening of valve margin; left posterior cardinal triangular
and inclined backward, with greatest relief near mid-length; on right
valve, anterior cardinal narrow but well developed; obsolescent right
posterior cardinal, formed by slight ridge along inner edge of nymph,
typically less prominent than corresponding groove behind left posterior
cardinal.
Narrow ligament nymphs separated from escutcheon by narrow liga-
ment furrow; ligament opisthodetic, external, about one-third of length
1968 BOYD AND NEWELL: HINGE GRADES 47
TABLE 5
MEASUREMENTS (IN MILLIMETERS) OF LEFT VALvEs oF Astartella aueri,
NEw SPECIES
(Specimens were selected from a larger size-graded series by means of a table of
random numbers.)
Length Height Convexity
15.7 15.0 4.0
15.3 14.5 5.0
13.9 12.7 3.0
13.9 11.8 3.5
13.6 12.2 4.7
13.2 12.3 3.5
13.1 12.1 3.4
13.0 12.1 4.5
12.4 10.9 2.7
12.1 11.8 3.6
10.9 10.1 2.8
10.9 9.9 3.0
9.4 8.0 2.7
9.1 7.8 2.6
8.5 7.7 1.8
7.9 7.7 1.8
7.7 7.0 2.2
7.6 6.6 1.5
7.4 6.5 aa
7.1 6.7 1.4
6.9 6.1 1.6
6.5 6.3 1.5
6.4 5.8 1.3
6.0 4.9 1.6
5.1 4.3 r2
of escutcheon; deep anterior adductor scar beneath lower end of lunule;
posterior adductor scar faint, slightly larger than anterior scar; small,
elongate, anterior pedal retractor scar behind and above anterior ad-
ductor; very faint posterior pedal retractor scar near dorsal margin of
posterior adductor; pallial line faint, without sinus; umbonal cavity
roofed by hinge plate; ventral edge of hinge plate declined forward.
VarIATION: The size distribution in 25 right and 25 left valves, chosen
by a table of random numbers, is shown in tables 4 and 5. The variation
in height relative to length is shown in figures 8G—J and 23. The spacing
of concentric ridges varies greatly and erratically (fig. 8D-F).
Valve convexity is variable, although the species is notably compressed
compared with other Paleozoic astartids (fig. 24). A very shallow sulcus
48 AMERICAN MUSEUM NOVITATES NO. 2328
Height mm.
16
12
Length mm.
4 8 12 16
Fic. 23. Height/length ratio in left valves of Astartella aueri, new species.
Data are in table 5.
is commonly present parallel to the posterodorsal margin and near it,
but in some valves this is represented only by a slight flattening of the
surface.
The left anterior cardinal varies in prominence with the degree of
thickening of the valve edge in the critical area. The degree of thicken-
ing varies from prominent to imperceptible. The curvature of the major
cardinal on the left valve increases as the tooth lengthens because the
ventral component of inclination increases during growth. In a number
of valves the sides of the major cardinal teeth and sockets are striated
(fig. 8C). Incomplete transposition of the dentition is illustrated by one
left valve and two right valves (fig. 7E, G). In each case, transposition
has not affected the posterior laterals.
Several valves exhibit vestiges of minute crenulations on their inner
ventral margins (fig. 22J). This feature is common in astartids from the
post-Paleozoic but rare in those from the Paleozoic. In a few valves, a
radial pattern is faintly visible as closely spaced black lines. These are
found in translucent areas and appear to be opaque features beneath the
1968 BOYD AND NEWELL: HINGE GRADES 49
Convexity mm.
o 9 e
oo 0 s eo
2 ° e e
o 8
[o] ° e e e
s eee 6
6 6 e
ae) ° e ‘
o 0 ° ‘id
e e e
e e
e e
1 o
ee
Length mm.
2 4 6 8
Fic. 24. Comparison of convexity/length ratio. Closed circles: Astartella
aueri, new species. Open circles: Astartella subquadrata Girty. The samples in-
clude numerous specimens from the Kaibab Limestone of central Arizona and
the Park City Formation of Beaver Creek, Wyoming.
valve surface (fig. 10C). Typical spacing of the lines is represented by
one valve 8 mm. in height in which the black lines are five per 1 mm.
in the ventral area and eight per 1 mm. in the posteroventral area. A
similar pattern was illustrated by Girty (1915, pl. 18, fig. 9) on a speci-
men of Astartella concentrica (=vera) from the Wewoka Formation of
Oklahoma which has three or four costae per 1 mm. in the depressed
bands between concentric ridges. Girty (p. 143) wrote that, in some cases
and perhaps in all, “this appearance is due to exfoliation and is prob-
ably to be connected with the rows of granules with which the margin
is progressively marked.” Girty (1915) reported that the valves show
around their free edges a row of beading or dentition (fig. 6C, D).
Comparisons: Astartella vallisneriana (King), common in the Zechstein
of Europe, has the ornamentation more prominent and more closely
spaced, greater length relative to height, and a less concave and less
steep anterior slope from the beak, than the Wyoming specimens. Astar-
tella subquadrata Girty, of the Kaibab, San Andres, Yeso, Phosphoria,
and equivalent formations in the western United States is more convex
50 AMERICAN MUSEUM NOVITATES NO. 2328
and has a lower cardinal area (escutcheon) than does the new species.
When convexity is plotted against length, the two species form adjacent
but distinct patterns on a scatter diagram (fig. 24). Another distinctive
difference between the two is that the beak in the new species is at the
apex of the valve, whereas in A. subquadrata the beak is downcurved
over the cardinal area. Girty’s description did not mention dentition,
but silicified specimens from the Kaibab Formation at the American
Museum were compared by us with the Wyoming specimens, and we
found that the dentition is essentially the same. Astartella nasuta Girty
from the Permian of the southwestern United States has a notably
truncate posterior.
OccurRENCE: Phosphoria Formation (Grandeur Member), Beaver
Creek, Wyoming. The new species is also represented in American Mu-
seum collections from the San Andres and Yeso formations and the
Road Canyon Formation (“Word No. 1” limestone). In all three cases,
A. subquadrata is also present. Ciriacks (1963) reported two specimens of
A. subquadrata in the Grandeur Member of the Phosphoria Formation,
but none was encountered in the present collection.
CATALOGUED SPECIMENS: Holotype, A.M.N.H. No. 28479; topotypes,
A.M.N.H. Nos. 28482, 28483, 28486, 28492-28505, 28507-28515; and
U.W. Nos. A1586, A1587.
LITERATURE CITED
BERNARD, F.
1895. Premiére note sur le développement et la morphologie de la coquille
chez les lamellibranches. Bull. Soc. Géol. France, vol. 23, pt. 3, pp.
104-154.
1896a. Deuxiéme note sur le développement et la morphologie de la coquille
chez les lamellibranches (taxodontes). Jbzd., vol. 24, pt. 3, pp. 54-82.
1896b. Troisiéme note sur le développement et la morphologie de la coquille
chez les lamellibranches (anisomyaires). Ibid, vol. 24, pt. 3, pp.
412-449.
1897. Quatriéme et derniére note sur le développement et la morphologie
de la coquille chez les lamellibranches. Jbid., vol. 24, pt. 3, pp.
559-566.
1898. Recherches ontogéniques et morphologiques sur la coquille des
lamellibranches. Ann. Sci. Nat. (Zool.), Paris, vol. 8, pp. 1-208,
pls. 1-12.
BEuUSHAUSEN, L.
1895. Die Lamellibranchiaten des rheinischen Devon mit Ausschluss der
Aviculiden. Abhandl. K. Preussischen Geol. Landesanst., new ser.,
vol. 17, pp. 1-514, pls. 1-38.
BorenaM, A. U. E.
1965. A revision of F. W. Hutton’s pelecypod species described in the
1968 BOYD AND NEWELL: HINGE GRADES 51
“Catalogue of Tertiary Mollusca and Echinodermata (1873).”
Paleont. Bull. New Zealand Geol. Surv., no. 37, 127 pp.
Branson, C. C.
1930. Paleontology and stratigraphy of the Phosphoria formation. Missouri
Univ. Studies, vol. 5, 99 pp., 16 pls.
Casey, R.
1952. Some genera and subgenera, mainly new, of Mesozoic heterodont
lamellibranchs. Proc. Malac. Soc., vol. 29, pt. 4, pp. 121-176, pls.
7-9.
CuHavan, A.
1952. Mélanges paléontologiques, 2. Distinction et classement des Crassa-
tellidés. Cahiers Géol. Thoiry, vol. 14, pp. 117-120, 1 fig.
Crriacks, K. W.
1963. Permian and Eotriassic bivalves of the middle Rockies. Bull. Amer.
Mus. Nat. Hist., vol. 125, pp. 1-100, figs. 1-4, pls. 1-16.
Dai, W. H.
1913. Pelecypoda. Jn Zittel, K. A. von, Textbook of paleontology. Trans-
lated and edited by Charles R. Eastman. Revised edition. London
and New York, the Macmillan Co., vol. 1, pp. 422-507.
Darracu, T. A.
1965a. Revision of the species of Eucrassatella and Spissatella in the Tertiary
of Victoria and Tasmania. Proc. Roy. Soc. Victoria, vol. 78, pt. 1,
pp. 95-114, pls. 12-15.
1965b. Hinge transposition in Fucrassatella (Pelecypoda: Crassatellidae).
Ibid., vol. 79, pt. 1, pp. 89-90, pl. 7.
Davies, A. M.
1935. Tertiary faunas. London, Thomas Murby and Co., vol. 1, x + 406
pp., 565 figs.
Dicxins, J. M.
1956. Permian pelecypods from the Carnarvon Basin, Western Australia.
Bull. Australian Bur. Min. Res., no. 29, 42 pp.
1961. Permian pelecypods newly recorded from eastern Australia. Palaeon-
tology, vol. 4, pt. 1, pp. 119-130, pl. 16.
1963. Permian pelecypods and gastropods from Western Australia. Bull.
Australian Bur. Min. Res., no. 63, pp. 1-150, pls. 1-20.
ETHERIDGE, R., JR.
1907. Official contributions to the paleontology of South Australia.
Adelaide, South Australia House of Assembly, Supplement to Par-
liamentary Paper, no. 55, 1906, pp. 1-21.
Girty, G. H.
1915. Fauna of the Wewoka Formation of Oklahoma. Bull. U. S. Geol.
Surv., no. 544, 353 pp.
Gotowkinsky, N. A.
1868. O permskoe Formation. Materialen zur Geol. Russlands, vol. 1,
pp. 273-415.
Harrer, J.
1959. Der Schlossbau friih-heterodonter Lamellibranchiaten aus dem
rheinischen Devon. Palaeontographica, vol. 112, Abt. A, pp. 133-192,
14 pls.
32 AMERICAN MUSEUM NOVITATES NO. 2328
Koroskov, I. A.
1954. Handbook on and systematic guide to the Tertiary Mollusca. La-
mellibranchia. Leningrad, State Scient.-Tech. Publishing Agency
Oil and Mineral Fuel Lit., 444 pp., 96 pls. (In Russian.)
Lamy, E.
1917. Révision des Crassatellidae vivants du Muséum d’Histoire Naturelle
de Paris. Jour. Conchyl., vol. 62, no. 4, pp. 197-270, pl. 6.
McAtgsteEr, A. L.
1965. Systematics, affinities, and life habits of Babinka, a transitional
Ordovician lucinoid bivalve. Palaeontology, vol. 8, pp. 231-246,
3 pls.
Mauauan, E. K.
1964. The Goose Egg Formation in the Laramie Range and adjacent parts
of southeastern Wyoming. Prof. Paper U. 8. Geol. Surv., no. 501-B,
pp. B-53-B-60.
MaxwELL, W. G. H.
1964. The geology of the Yarrol region. Part 1, Biostratigraphy. Univ.
Queensland Papers, vol. 5, no. 9, 79 pp., 14 pls.
NEWELL, N. D.
1939. Transposed hinge in a Paleozoic pelecypod. Amer. Jour. Sci., vol.
237, pp. 178-180.
1940. Invertebrate fauna of the late Permian Whitehorse Sandstone. Bull.
Geol. Soc. Amer., vol. 51, pp. 261-336, 10 pls.
1955. Permian pelecypods of East Greenland. Meddel. om Grgnland,
vol. 110, no. 4, 36 pp., 5 pls.
1958. A note on Permian crassatellid pelecypods. Amer. Mus. Novitates,
no. 1878, pp. 1-16.
Nico , D.
1955. Morphology of Astartella, a primitive heterodont pelecypod. Jour.
Paleont., vol. 29, no. 1, pp. 155-158.
Popenog, W. P., AND W. A. FINDLAY
1933. Transposed hinge structures in Lamellibranches. Trans. San Diego
Soc. Nat. Hist., vol. 7, no. 26, pp. 299-318, pl. 19.
Reep, F. R. C.
1932. New fossils from the agglomeratic slate of Kashmir. Palaeont.
Indica, new ser., vol. 20, pp. 1-79, pls. 1-13.
Tuomas, G. A., AND J. M. Dickins
1954. Correlation and age of the marine Permian formations of Western
Australia. Australian Jour. Sci., vol. 16, pp. 219-223.
WANNER, C.
1940. Neue Permische Lamellibranchiaten von Timor. Jn Brouwer, H. E.,
Geological expedition of the University of Amsterdam to the Lesser
unda Islands in. . . 1937. Amsterdam, vol. 2, pp. 312-395.
WEAVER, D: W.
1963. Transposed hinge of a crassatellid. Jour. Paleont., vol. 37, no. 1,
pp. 294-296.
YAKovLev, N. N.
1928. Procrassatella, un genre nouveau du Permien. Ann. Soc. Paleont.
Russie, vol. 7, pp. 119-125.
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