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itteliana

Abhandlungen der Bayerischen Staatssammlung für Paläontologie
und historische Geologie

Begründet von Prof. Dr. Richard Dehm

PETER SPRECHMANN

The Paleoecology and Paleogeography of the Uruguayan Coastal Area

During the Neogene and Quaternary

JOHN H. OSTROM

The Osteology of Compsognathus longipes WAGNER

MÜNCHEN 1978

Zitteliana | 4 | 118 Seiten | 14 Tafeln | München, 1. August 1978 [isn 0373-9627

Herausgegeben von Prof. Dr. Dietrich Herm,
Bayerische Staatssammlung für Paläontologie
und historische Geologie München

Redaktion: Dr. Peter Wellnhofer
ISSN 0373 - 9627

Zitteliana

Abhandlungen der Bayerischen Staatssammlung für Paläontologie
und historische Geologie

Begründet von Prof. Dr. Richard Dehm

PETER SPRECHMANN

The Paleoecology and Paleogeography of the Uruguayan Coastal Area
te) © o . o J

During the Neogene and Quaternary

JOHN H. OSTROM

The Osteology of Compsognathus longifes WAGNER

MÜNCHEN 1978

ISSN 0373 - 9627

| Zitteliana | 4 | 118 Seiten 14 Tafeln München, 1. August 1978

Gesamtherstellung: Druck- und Verlagsanstalt Gebr. Geiselberger, Altötting

The Paleoecology and Paleogeography of the Uruguayan
Coastal Area During the Neogene and Quaternary')

PETER SPRECHMANN?)

With 16 text figures and plates 1—6

ABSTRACT

Miocene, Pleistocene and Holocene foraminiferal
and molluscan assemblages found in water wells and
outcrops distributed along nearly 700 km of the
coastal plain of Uruguay were analyzed. Marine
Miocene faunas were found only in the Chuy No. 364
well. Faunal associations using well data were cor-
related by ecostratigraphic unit. Depositional envi-
ronments of Neogene and Quaternary foraminiferids
and molluscan bearing strata were reconstructed. The
distributional pattern of the various faunas that today
populate the Rio de la Plata are analyzed in reference
to the salinity gradient of the estuary. Asa tool the
Curve of REMANE for foraminiferids and bivalves is

used, as well as the distributional pattern of gas-
tropods. Various criteria for the recognition of ancient
estuaries are proposed. The early Holocene paleogeo-
graphy in the Rio de la Plata was reconstructed.
A reconstruction of the Miocene and Quaternary
geological evolution in the southernmost part of the
Pelotas Basin (area of Chuy) since the Miocene is
attempted. This is characterized by the alternation of
marine (or marginal marine) and terrestrial depositio-
nal environments. The distribution of the paleozoo-
geographical littoral provinces of the eastern coast of
South America during the Miocene and lower Hol-
ocene is elucidated.

KIÜURZEASSUN.G

Es werden Foraminiferen- und Mollusken-Verge-
sellschaftungen aus dem Miozän, Pleistozän und Holo-
zän untersucht, die aus hydrogeologischen Bohrungen
und Aufschlüssen entlang einer Strecke von ca. 700 km
der Uruguayischen Küstenregion stammen. Die Asso-
ziationen aus dem Miozän kommen aus einer einzigen
Bohrung (Chuy Nr. 364). Die Fauna der Bohrungen
wird ökostratigraphisch gegliedert; daraus werden die
Ablagerungsräume im Neogen und Quartär rekonstru-
iert. Die gegenwärtige Zonierung verschiedener Fau-
nen auf Grund von Salinitätsgradienten im La-Plata-
Astuar wird untersucht. Hierzu dient die REMANE-
Kurve für die Foraminiferen und die Muscheln, sowie

die Verbreitung der Schnecken. Daraus ergeben sich
Kriterien für die Erkennung ehemaiger Ästuare. Die
Paläogeographie des Gebietes des La-Plata-Astuars
während des unteren Holozäns wurde rekonstruiert.
Die geologische Entwicklung im südlichen Teil des
Pelotas-Beckens (Chuy-Gebiet) während des Miozäns
und Quartärs wird rekonstruiert. Es ist gekennzeichnet
durch ein Ineinandergreifen mariner (oder marginal
mariner) und kontinentaler Verhältnisse.

Abschließend wird ein Überblick über die litoralen
paläozoogeographischen Provinzen an der Ostküste
Südamerikas während des Miozäns und Holozäns ge-
geben.

RESUMEN

Se estudian asociaciones de foraminiferos y de
moluscos del Mioceno, Pleistoceno y Holoceno ha-
lladas en perforaciones hidrogeolögicas y en aflora-
mientos situados a lo largo de casi 700 km de la planicie
costera del Uruguay. Unicamente se hallaron asocia-
ciones Miocenicas en la Perf. Chuy N° 364. La
fauna de las perforaciones se correlaciona ecoestrati-
gräficamente. Se reconstruyen los ambientes de

deposiciön de las secuencias del Neögeno y Cuartario
portadoras de foraminiferos y de moluscos. Asimis-
mo se analıza el padrön de distribuciön de la fauna

1) Fossil-Vergesellschaftungen No. 76. — No.75: BECKER,
G., Clausthaler Abh., 1979.

2) Dr. PETER SPRECHMANN, Institut und Museum für
Geologie und Paläontologie, Sigwartstr. 10, D-7400 Tübin-
gen, West-Germany.

que puebla actualmente el Rio de la Plata en base al
gradiente de salinidad, utilizändose la Curva de
REMANE de los foraminiferos y los bivalvos, y la
distribuciön de los gaströpodos en el estuario. Se
proponen varios criterios para la identificaciön de
estuariales antiguos. Se reconstruye la
paleogeografia de la regiön del Rio de la Plata
durante el Holoceno inferior. Por otra parte se

ambientes

describe la evoluciön geolögica acaecida en el extremo
sur de la Cuenca de Pelotas (ärea del Chuy) desde el
Mioceno, caracterizada por la alternancia de depösitos
marinos (o marginal marinos) y continentales. Final-
mente se analiza la distribuciöon de las provincias
paleozoogeogräficas litorales de la costa oriental de
America del Sur durante el Mioceno y Holoceno
inferior.

TABLEOKEONTENTS

I. Preface 5
II. Introduction: Geological ren 5
III. Geographical position and characteristics ei the bore- holes 5
IV. Methods and material 7
V. Marine Miocene . . 8
A. Location of Chuy No 364 B 8
B. Previous poleontological, geological and el er EHäl: 8
€. Distribution of the,micro- and macrofaunas . . . 0... 0. we 8
D. Microfaunal age . 11
E. Correlations 12
F. Paleoecology Er 12
1. General ee e: the Korn e associations nr 12
2. Analysis of microfaunal mixing 13
3. Possible depositional environments SR 15
4. Paleoecological results gen by Dre enkerali associations wre a al
VI. Quaternary ZR 18
A. General een al re oe on ee arnerg WELS
B. Distribution of the microfossils and macrofossils . . » » 2 2 2 2 2220.00 18
C. Ages of the fossil assemblages 30
D. Stratigraphy ; Sie: 31
E. Upper Pleistocene en Hiolocene Be of the Rio de IS Placa FERIONG: = nl
F. Paleoecology . . 32
1. The Rio de la Plata ee 32
a. Physical characteristics . u: 32
b. Previous work on living kararatnıkeridh And abrans Eu Say rn BE 033
c. Characteristics of the foraminiferal biocoenosis . 33
d. REMANE’s curve for the foraminiferal biocoenosis of the Rio delaPlatan.. 34
2. Paleoecological interpretation based on foraminiferids . . . : 34
3. Paleoecological conclusions of Eee environments based on Penie

foraminiferids : ee 35
4. Paleoecological i een oe mo Hasen EsenbiBe ge re A ee
a. Methods I RSS
b. Curve of REMANE for Ei: De ke ME Rio ae 15 Plata Eee 39
Life habits of the dominant genuine brackish-water species . . . 42

c. Distribution of the living ode in the Rio de la Plata a ze: its
zone of influence re 42
d. Reconstruction of een Astereile environments . 2 2220.20. 44
Identification of euryhaline bivalve and gastropod species . . . 48

e. Paleoecological reconstruction on molluscs from additional Tocaligee en the
Querandina Transgression 48
5. Depositional environments erened 5 weil anne ma in SP re 50
G. Biostratigraphy : a: 50
1. Ecostratigraphic eo laione : 50

2. Data showing that the et zones ben er de Vruguayan Or
nary are ne En: 50
H. Results of the Holocene Baleographyi in che Rio = la Plata resion, ee
VII. Conclusions about the Neogen-Quaternary evolution in the Chuyarea . . . .... 52
VIII. Distribution of the paleozoogeographical littoral provinces . . » 2 2 2220.20. 53
A. Miocene : Enke 54
B. Pliocene 57
C. Quaternary 58
IX. Faunal reference list . 59
A. Foraminiferids 59
B. Molluscs £ 62
X. Summary and et & 63
XI. Literature cited 65

TPRREFANCE

This study was a research program for the development
of micropaleontology and paleoecology in Uruguay with
the support of Dr. R. Mendez-Alzola.

The Alexander von Humboldt Foundation supported the
realization of this study by a research fellowship which was
carried out in the Institut und Museum für Geologie und
Paläontologie der Universität Tübingen. Dr. D. Herm acted
as academic supervisor and coordinator and Dr. J. Wendt
as referee. The publication of the results has been possi-
ble due to a financial support to the printing costs by the
Alexander von Humboldt Foundation.

In this thesis J. da Silva helped with the preparation of
bore-hole samples and evaluating lithological and stratigra-
phic data, A. Figueiras with the taxonomic determination
of macro- and micromolluscs, V. Scarabino with the taxo-
nomic determination of macromolluscs, H. Goso with the
stratigraphic interpretation of Chuy N° 364, S.C. Bender
Kotzian with the taxonomic determination of ostracods,
and Dr. M. Scherer in the X-ray diffraction analysis. Va-

luable SEM work and photos were made with the expert
help of Ms. R. Klett and Mr. W. Wetzel respectively.

Productive and beneficial suggestions, discussions and
criticism were also made by Drs. A. Seilacher, F. Frölicher,
F. Fürsich, Ch. Hemleben, W. v. Koenigswald, A. Liebau,
W. Reif and D. Hilgemann.

For the taxonomic determination of the foraminiferids,
comparisons were made with the collections of the Museo
Argentino de Ciencias Naturales “Bernardino Rivadavia”
(Buenos Aires) and Departamento de Paleontologia y Estra-
tigrafia-Instituto de Geociencias (Porto Alegre) with the
assistence of Drs. E. Boltovskoy, A. Bertels and M. Madeira-
Falcetta. 'The bore-hole samples were provided by the Ins-
tituto Geolögico del Uruguay.

To all the above institutions and persons many thanks are
due.

The largest helping of thanks are due to my wife Ana
Maria who typed the manuscript and also my entire family
and friends who kept me going and alive through these
years of work.

IINIROBDUCHON:
GCEOFOGIERZSETIING

During the Cenozoic, sedimentation in Uruguay
was predominately continental. Marine fossils were
only found in exposures from the Camacho Formation
(= Entrerriana) and Vizcaino Formation (= Queran-
dina); and in some subsurface (well) sequences attri-
buted to the Chuy Formation.

Features of regional geology in the area of study
were summarized by Bossı (1966), Bossı et al. (1975)
and DELAnEY (1967, 1969 ?).

In the course of the last twenty years several
schemes were presented in an attempt to explain the
geological evolution of Uruguay during the Tertiary
and/or Quaternary (Bossı, 1966, 1969; Bosst et al.
1975; Caorsı & GoNı, 1958; DELANEY, 1967, 1969?;
Francıs, 1975; GoNı & HorrsSTETTER, 1964; Goso,
1965, 1972; HARRINGTon, 1956; Paropız, 1969;
TRICART, 1972). Some of these schemes are summarized
in Table I. The analysis of these research publications
shows a progressive increase in knowledge of the
Uruguayan Cenozoic, although their conclusions were

repeatedly contradictory. Furthermore extended
regions were not even mapped in detail. No precise

biostratigraphical studies have been made.

The greatest amount of disagreement is present in
reference to relationships existing between stratigra-
phical units and their age (table I). The Camacho
Formation is a good example of this situation. Two
points of view have been given of its age: a) The
Camacho Formation is ancient, belonging to the
Miocene or lower Pliocene. This was the first opinion
and was Darwın’s, and traditionally was shared by
MENDEZ-ALZOLA, FRENGUELLI, SERRA, LAMBERT,
FIGUEIRAS & Brot, PAroDız, among others; b) The
Camacho Formation is modern, being placed within
upper Pliocene (Francıs, 1975; Montes, 1975) or into
the lower Quaternary (BERTELS & MADEIRA-FALCETTA,
1977; Cross, 1966a ; DELANEY, 1967, 1969?; ECOCHARD,
1970; Goso, 1972; TRrıcarT, 1972). The age given to
this marker horizon has direct implications in the
reconstruction of this area, as will be shown.

IMIGEOGRAPHICAT BOSTIIION
INIDIGELARACTERTSTIES ©E
IEIE- BORE-FIOTFES

The paleontological material analysed in this work
was obtained from drillings made during a search for
drinking water, and from an outcrop located in
Parque Lecocq. The wells were made by the “Insti-
tuto Geolögico del Uruguay”. The samples are
deposited in the “Secciön Hidrologia y Servicio de

Perforaciones” of the above mentioned institution.
Almost all of the wells were drilled by the cable-tool
method. There were no continuous cores available,
and the samples came from drill cuttings which were
in chip and/or powder form. As ToomEY & WINLAND
(1973) have shown, the information for an identifi-

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cation of facies and microfaunas can be obtained from
examination of drill cuttings. Nevertheless, this fact
reduces part of the available information, because the
sedimentary structures are not preserved, and a por-
tion of the macrofossils were broken.

The location of the bore-holes are shown in Fig. 1.
They are located on the Uruguayan coastal plain area.
The geographic inner limit of the coastal plain usually

SOR IANO N? 48372
RIO ruauar N® 445 /1 EM

CARMELO N® 235

forms the contact with the underlying crystalline
rocks. This contact is usually marked by a low
sloping topographic escarpment which occurs between
the 20 and 40 meter contour lines on the topographic
maps (DELANEY, 1967, 1969?).

For each well the geographic coordinates are given
according to the “Carta del Uruguay al Millonesimo”,
edited in 1971 by the “Servicio Geogräfico y Militar”.

PUEBLÖ SAN LUIS
N= 107271

CHUY’N? 364

18 DE JULIO N
Fi

LA CORONILLA a A 811

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VNE NS 291/1 SAN JOSE DE SEA
N DE LA CARRASCO LA PALOMA N? 482/1 FF
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o 50 100 km. 57° 58° 55° 54°

Fig. 1:

Bore-hole locations dealt with in the text.

IV.METHODS AND MATERIAL

140—150 cm? of sediment from each sample of
drill cutting was picked clean of all megafauna (mol-
luscs and barnacle plates). 35—40 cm® of the above
140—150 cm? was then inspected for microfauna.
This is equivalent to a core sample 4—5 mm high and
10 cm in diameter.

Samples were prepared in 15% H,O,, washed,
sieved (0,063 mm mesh net), and dried. In a smaller
number of samples, so marked in Chapter VI-B, the
tests were separated out by flotation in carbontetrach-
loride. The samples were then sieved as above. The
rest of the sediment was inspected under the binocular
microscope to check for any remaining microfossils in

the residue. All tests were removed, taxonomically
identified and counted. The photographs were made
with a Cambridge Stereoscan electron microscope
Type Mark 2 A.

The illustrated and photographed foraminiferids
are deposited in the Bayerische Staatssammlung für
Paläontologie und historische Geologie, Munich, N°.
1978 VIII. The bore-hole samples, the molluscs of
the wells, and remaining microfossils are deposited in
the Instituto Geolögico del Uruguay and the Depar-
tamento de Paleontologia, Facultad de Humanidades
y Ciencias, Uruguay.

V. MARINE MIOCENE

Marine Miocene faunas were found only in one
well: Chuy N° 364.

A. Location of Chuy N° 364

City of Chuy, Rocha County (Lat. 33°42’S, Long.
53°26’W) (fig. 1). Geomorphologically this region
belongs to the coastal plain of southen Brazil and
tectonically to the Pelotas Basin (DELANEY, 1965,
1966).

B. Previous paleontological, geological
and stratigraphical studies

This well has been the object of repeated studies, as
it presently gives the most complete information about
the evolution of the upper Tertiary and Quaternary of
Uruguay (ANTÖN & ARMSTRONG, 1973; BERTELS &
MADEIRA-FALCETTA, 1977; Bossı, 1966; CLoss, 1966a,
1970; Cross & MADEIRA, 1968a; ECOCHARD, 1970;
FıisuEirAs & Broccı, 1971, 1972/73; Francıs, 1975;
Goso, 1972; MaruMIan, 1970, 1972; MEDINA, 1962).

The following publications provide taxonomic de-
scriptons of the macro- and microfossils previously
found in Chuy N° 364: 1) Mepına (1962) studied
the macrofauna of a single fossil level, at depth of
124 m, 2) Cross & Mapeıra (1968a) studied the
microfauans of this well and described three fo-
miniferid bearing beds, and 3) FıcuEıras & Broccı
(1971, 1972/73) compiled a review of the molluscan
fauna of the Camacho Formation. They include in
this study the Chuy well. They also reviewed syste-

matically the species previously described by MEDInA
(1962), and proposed a modified taxonomy, hence-
forth used in this work.

C. Distribution of the micro- and macro-
faunas

The distribution of the Miocene micro- and macro-
faunas is shown in Table II. Remarks:

1) Mollusca: The species which were described
by MeoınaA (1962) are marked with “M” in Table II.
The species described by Fıcuziras & Broccı (1971,
1972/73) are marked with “FB” in the same Table.
The disintegration of the drill cuttings with H,O,
for micropaleontological porposes gave additional
material not previously cited. In Table II these fossils
are marked with “x”.

Some remarks are made about the systematics of molluscs
in Table II: a) Semele sp., was described as Semele bravar-
diana (in litt) by Fıcuzıras & Broccı (1972/73), b)
Ostrea sp., was previously cited as Ostrea patagonica by
FıguEiras & Broccı (1972/73), and c) Americuna sp.: is a
form that probably represents a new species. The genus
Americuna was described on the basis of a single living
species, Americuna besnardi (Cox, NewEıLı, Boyp et al.,
1969; KLAPPENBACH, 1962).

2) Brachiopoda: Mepına (1962) shows the
presence of Bouchardia transplatina Inzerınc, 1907,
at a depth of 124 m.

3) Bryozoa: The presence of the bryozoans
Cellaria and Discoporella between 124—125 m was
previously indicated by Cross (1966a) and Cross &
Mapeıra (1968a).

Faunal distribution in Chuy No 364

Depth/m

FORAMINIFERA

Ammonia beccarii var. parkinsoniana
Ampbhistegina gibbosa
Buccella peruviana, s. |.
Cancris sagra

Cassidulina curvata
Cassidulina laevigata
Cassidulina subglobosa
Cibicides aknerianus
Cibicides “pseudoungerianus”
Cibicides sp.?
Discorbinella® bertheloti f. boueana
Elphidium depressulum
Elphidium discoidale
Elphidium gunteri
Elphidium aff. sagrum
Elphidium cf. tuberculatum
Elphidium sp. A

Elphidium sp.

Fursenkoina sp.

Lagena laevis f. perlucida
Lagena sp.

Lenticulina rotulata
Marginulina gr. tenuis
Massilina secans
Miliammina fusca
Miliolinella subrotunda
Nonionella atlantica
Nonionella auricula

Nonion grateloupii

Nonion sp. A

Nonion sp. B

Oolina melo

Poroeponides lateralis
Pyrgo nasuta
Quingqueloculina agglutinata
Quinqueloculina patagonica
Quinqueloculina seminulum
Quingqueloculina vulgaris
Quinqueloculina sp. A
Quinqueloculina sp. B
Quinqueloculina sp. C
Quinqueloculina div. spp. indet.
Rotorbinella rosea
Textularia gramen
Textularia sp. A

References: Numbers of foraminiferids:

TABLE II

122 124 125 128
124 125 128 130
UO00
ee Fee ..
Ele] =
.. .. D .
+ (1) ee. (2—5)
— (6—10) — — (11—20)
(21—40) UDD (41-80)

L_] (81—160)

130
133

Depth/m

BIVALVIA

Adrana sp.
Americuna sp.
Amiantis purpurata
Anadara sp.

Cardita sp.

Chione doello-juradoi

Chione meridionalis burmeisteri

Chione sp.
Codakia sp.
Corbula caribaea
Corbula pulchella
Cyrtopleura lanceolata ornata
Diplodonta vilardeboana
Diplodonta sp.
Glycymeris sp.
Laevicardium sp.?
Lucina sp.
Mactra bonariensis
Mactra sp.
Mactrellona sp.
Nucula sp.
Nuculana sp.
Ostrea sp.
Plicatula sp.
Semele sp.
Solen sp.?
Tagelus plebeius entrerianus
Tellina sp.
Tivela (Eutivela) isabelleana
Tivela sp.
debris

GASTROPODA

Anachis sp.
Caecum (Micranellum) sp.
Calliostoma sp.
Epitonium sp.
Halistylus columna
Iselica anomala
“Marginella” sp.
Odostomia sp.
Olivancillaria urceus
Olivella (O.) puelcha
Olivella sp.
Polinices entrerriana
Tegula sp.
Turbonilla (Pyrgiscus) sp.
Turritella sp.

debris

POLYPLACOPHORA
Chaetopleura sp.

SCAPHOPODA

Dentalium sp.

TABLE II (continued)
Faunal distribution in Chuy N?° 364

113 115 117
115 117 120

FB FB

FB x

”

120
122

122
124

H"HMMH

124
125

»EMMEZ

130
133

TABLE II (continued)
Faunal distribution in Chuy N?® 364

Depth/m 113 115
115 117

BRACHIOPODA
Bouchardia transplatina

OSTRACODA?)
Bairdia

Buntonia
Caudites
Callistocythere
Cytherelloidea
Cytheretta
Cytheropteron
Krithe
Loxoconcha
Mutilus
Paradoxostoma
Procytheropteron
div. ssp. indet.
BALANOMORPHA

Balanus sp. (barnacle plates) B x

BRYOZOA
Cellaria sp.
Discoporella sp.
ECHINOIDEA-REGULARIA
spines
plates
CHONDRICHTHYES
teeths

OSTEICHTHYES
debris

OTOLITHS

117 120 122 124 125 128 130
120 122 124 125 128 130 133

M
x
x
x
x
x
x
x
x
x x
x
x
x
x x
x x x x x x
x x x x
x x x x x
x x x x
x
& x
x
x x x

D. Microfaunal age

No planktonic foraminiferal associations are
contained in the 122.10—133.00 m sequences in Chuy
N° 364. Age dating was based on benthic species,
which generally are not adequate for these purposes.

The microfauna of the 124—125 m sample is con-
sidered to be of Miocene age (Cross, 1966a, 1966b,
1970, 1971; Cross & MADEIRA, 1968a). The mala-
cological associations of this well were included in the
upper Miocene (FıGuEiras & Broccı, 1971, 1972/73).
On the other hand BERTELS & MADEIRA-FALCETTA

3) Additional abundant ostracods were found in the 122.
10—124.00 m level sample, and scarce specimens from the
124.00—125.40 m level. This material was also given to
Prof. Korzıan for taxonomic identification.

(1977) states that only Pleistocene foraminiferids are
present in this well.

It must be pointed out, that the subdivision of the
marine Miocene on the South American atlantic
borderland is very controversial.

In Argentina the known assemblages are characteri-
stic of shallow environments. MALUMIAN & Masıuk
(1973) distinguish between: 1) lower and middle
Miocene assemblages; and 2) upper Miocene-Pliocene?
assemblages. BERTELS (1975) also distinguishes between
two units: 1) the Superpatagonian, which is correlated
with the Aquitanian; and 2) the Entrerrian, which is
tentatively considered to belong to the Tortonian.

In southern Brazil the Miocene associations found in
the Pelotas Basin contain numerous planktonic fo-

raminiferal species, which are situated near the
boundary of the Globigerinatella insueta and Globo-
rotalia foshi barisanensis-Zones of the Trinidad se-
quences (Cross, 1966a, 1967, 1970). The Globorotalia
foshi barisanensis-Zone is equivalent to the Globoro-
talia foshi peripheroronda-Zone (Nocurı, 1975).

Species in the phylogenetic line Globigerinoides
bisphericus-Orbulina suturalis are also found. They
belong to the „Orbulina-Surface“ (Cross, 1966a,
19665, 1967). Globigerinoides bisphericus Toon, 1954
is considered by Nocuri (1975) to be a synonym of
Globigerinoides sicanus DE STEFANI, 1951.

The ages attributed to these zones is very controver-
sial. Some authors place them in the Aquitanian/
Burdigalian boundary; others in the Tortonian (Cross,
1966a, 1966b, 1967, 1970, 1971; Cross & MADEIRA,
1968a). Nocurı (1975) believes that the planktonic
foraminiferids found in the Pelotas Basin indicate a
lower Miocene age. TROELSEN & Quapros (1971)
analysed the calcareous nanoplankton found at a
depth of 716 m in the well N® 2-MO-1-RS, located
in the Pelotas Basin. They indicate a probable lower
Miocene age. BERTELS & MADEIRA-FALCETTA (1977,
p. 446) indicated that the transgression in the Pelotas
Basin took place in late Miocene times, i. e., approxi-
mately at Zone N 14 of Brow. This is supported by
the presence of Globorotalia acostaensis, Globigerina

nepenthes and other planktonic species. They also
state that the series described by Cross (1966a, 1970),
as well as other lower Miocene assemblages, were pro-
bably reworked from adjacent areas.

Elphidium cf. tuberculatum was found in Chuy
N°® 364 between 122.10—133.00 m. The first
reference of the existence of this species in South
America was given by MarumIan (1970), who makes
several remarks about the chronological worth of
Elphidium tuberculatum. This species indicates an
upper Miocene-Pliocene? age.

The associations found in Chuy N° 364 between
122.10— 133.00 m certainly belongtothe Miocene
for three reasons:

1) They are related with the faunas of the Pelotas
Basin, and those of the Entrerrian Stage (= Entrer-
riense) of Argentina;

2) Paleoclimatologically the associations of foramini-
ferids, gastropods and bivalves indicate warm waters.
The existence of these warm temperatures in the area
point out a Miocene age (see Chapter VIII); and

3) Marine Pliocene sediments seem to be absent in the
South American atlantic borderland (BArTELs, 1975;
BERTELS & MADEIRA-FALCETTA, 1977).

There are no objective facts that permit the assig-
ning of these assembleges of Chuy N° 364 to a certain
stage or epoch within the Miocene.

E. Correlations

The microfauna found in the 124—125 m sample
has been correlated with the Miocene sequences
belonging to the “Orbulina-Surface” from different
wells of the Pelotas Basin (Cross, 1966a, 1970; Cross
& MaADeıra, 1968a). On the other hand, the Mio-
cene sequences belonging to the wells drilled in the
Pelotas Basin were separated into four subdivisions,
named Mio 1, 2, 3 and 4 (Cross, 1970). The Miocene
foraminiferal associations belonging to Chuy N° 364
are similar to those of Mio 1.

The time-stratigraphic correlation between the Las
Flores N° 24 and Monte Veloz N? 1 wells (Buenos
Aires County, Argentina) is clear. The faunal sequen-
ces found in Chuy N° 364 between 122.10— 133.00 m
belong to the “Protelphidium” tuberculatum-zone.
This local informal zone (“hemerozona”) was pro-
posed by Marumian (1970) and represents the “Pa-
ranense-Entrerriense Transgression”.

F. Paleoecology

1. GENERAL CHARACTERISTICS OF THE
FORAMINIFERAL ASSOCIATIONS

Only benthic species were found, whereas the
planktonic foraminifera were completely absent.

For the most part the species found still exist today.
This offers an excellent opportunity to establish
paleoecological conclusions supported by present con-
ditions. It allows the utilization and evaluation of
ecological and biogeographical data that are available
from the living fauna today.

In analyzing the Miocene associations, data per-
taining to the present time foraminiferal fauna of
Brazilian oceanic coasts will be used repeatedly
(BoLrovskoy, 1959a, 1961, 1970a, 1976; BOLTOVSKOY
& Lena, 1966; CARVALHO & CHERMONT, 1952; CLoss
& BARBERENA, 1960a, 1960b, 1962; CusHMAN &
PARKER, 1931; MADEIRA-FALCETTA, 1974; NARcHI,
1956; PEREIRA, 1969; Roprıcuzs, 1968, 1971, 1972;

ROETTGER, 1970, 1973; Rısas, 1971; Tınoco; 1955,
1965/66, 1971, 1972). Almost all available informa-
tion is contained in papers based on the study of empty
tests.

Unfortunately only a few studies have differen-
tiated between foraminiferids bearing protoplasm at
collection time, and those which belong to the than-
atocoenosis.

Murray (1968, 1973, 1976) proposed two criteria
which are useful for characterizing foraminiferal asso-
ciations:

a. Diversity. In order to determine they diver-
sity the Fischer a index was used. Only samples with
more than 100 specimens were evaluated. The follo-
wing index values were obtained (fig. 2): «a = 6
(128.00—125.40 m), a = 5 (125.40—124.00 m) and
a = 8 (124.00—122.10 m).

b. Triangular plot of suborders. In
plotting this diagram the occurence of the suborders
Rotaliina-Miliolina-Textulariina is presented in per-
centile figures (fig. 2). This diagram although not a
triangle, is similar in information presented (MURRAY,
1973, fig. 103).

2. ANALYSIS OF MICROFAUNAL MIXING

The distribution of the microfauna in shallow
waters is affected to a large extent by displacement
and mixing (HErm, 1969; Lıesau, 1975). The forms
found in a certain fossil assemblage do not exactly
represent an ancient biotope. They do not automati-
cally identify an ancient biocoenosis, neither in its
qualitative or quantitative spectrum. The fossil fauna
is a post mortum association resulting in the inter-
action of sedimentological factors such as transport;
and fossil diagenesis. Through this mechanism a
vertically mixed condensate is formed which incor-
porates epi- and endobenthic elements mixing those
forms originating from the phytal with those of the
pelagic environments. Studies made in one and the
same region, in which living foraminiferids and empty
tests were examined separately, demonstrate this phe-
nomena clearly. Examples with special reference to
foraminiferids are summarized by BoLrovskoY (1965),
Borrovskoy & WRIGHT (1976), GRABERT (1971),
Pujos (1971) and Murray (1973, 1976). The transport
originated by the current and the wave action can
cause a selection or separation which is characteristic
for the fossil microfauna. In contrast, submarine
displacements or slumps can produce unmodified
unmixed allochthonous faunal spectra.

The analysis of mixed microfaunal assemblages
must be identified as to the autochthonous and alloch-
thonous components which generally are contained in
microfossil assemblages.

First it is necessary to establish the type of sediments

in which the foraminiferids were found, and the type
of preservation of its tests.

The sediment lithofacies were described by Antön
& ArmsTronG (1973). Between 133.00—130.00 m
loose quartz in size from coarse sand to granules was
found. They contain pebbles of the “San Miguel”
granophyre. The few foraminiferal tests that were
found show evident abrasion signs and are size sorted.
The sediments of the 130.00—128.00 m level of the
core sample was made up of coarse quartz sands to
granules sized particles. "They also contain gravels of
the “San Miguel” granophyre, which indicates the
proximity of the sediment source.

Grain size decreases gradually, whereas the number
of foraminiferal tests increases gradually. Between
128.00— 125.40 m loose coarse quartz sand to granule
deposites were found. Among 125.40—124.00 m fine
quartz sand to granule deposits were found. Between
124.00 and 122.10 m level the sample shows fine
quartzose sands. It is subangular and well sorted.

Preservation of the foraminiferal
tests: The difference between autochthonous and
allochthonous elements is primarily established with
the help of Amphistegina gibbosa as this species is an
excellent indicator for salinity, temperature and
bathymetry (see pages 15—16).

The tests from the adult specimens of this species
are found:

a) well preserved, frequently showing small frac-
tures.

b) with polished exterior wall.

c) poorly preserved with large fractures.

This preservation observed from the tests of Ampbi-
stegina gibbosa can be explained by the following: 1)
The tests come from a high energy biotope, where they
are exposed to rolling in the substrate while still alive.

2) In high energy environments the tests are affected by
postmortem transport. Only tests with thick and
resistent walls are preserved, the rest is destroyed. 3)
The effect of selective postmortem transport, that is
governed by sedimentological laws, and consequently
a size sorting.

At 122.10—125.40 m the tests of Ampbistegina
gibbosa constitute 12/o of the foraminiferal assembla-
ges. The type a) and b) of preservation could be ex-
plained with the concept of the “rolled-abraded”
foraminiferids (in German “Abroll” Foraminiferen)
introduced by Lıiesau (1975, p. 375) who specially
applied it to Amphistegina. The “rolled-abraded”
foraminiferids are forms adapted to live in the sedi-
ment and are subject to rolling during life. These are
adapted in life to a high energy biotope, where active
sediment transport takes place. Generally the tests of
the “rolled-abraded” foraminiferids are found in
great numbers, and almost always evidence of rolling
and abrasion is found. Therefore this preservation

CHUY No. 364 4 index

Stratigraphic section 0 ı00
Depth/m

0
7 Zozaz POLORES

TZ FT cHuYesstI

27
30

40 CHUY SU)

= CHUYcS.DI

RAIGON

CAMACHO

suborders

% 100 0

X Rotaliina
® Miliolina

Dominance WATER DEPTH
% 100 Shallow Depth

S 50
Variability ?

® Faunal dominance
% Faunal variability

Fig.2: Chuy N°® 364 stratigraphic section. Different paramenters used in the text are plotted
against the water depth. Key: a= mud, b = sandy silty mud, c = sandy mud, d = muddy
sandstone, e = very fine to fine sands, f = poorly sorted sands of fine to granule quartz sand,

logical section based on ANTON & ArMSTRONg’s (1973) rock descriptions].

g = coarse to granule sized quartz sand, h = terrestrial environments, i = bedrock. [Litho-

speakes for the fact that Amphistegina gibbosa is par-
authochthonous. The term par-authochtonous is used
according to HErM’s (1969, p. 83) definition.

With the adult tests, juvenile specimens of Amphi-
stegina gibbosa were also found. This fact confirms
that this species is a par-autochthonous form. The
presence of poorly preserved tests of Amphistegina
gibbosa with large fractures and abrasions also points
to the same cause as in 2) above.

The increase of the per cent fraction occurence of
Ampbistegina gibbosa between 125.40—133.00 m is
directly proportional to the size of the sediments
grains (fig. 2). That means thata selection takes place
after death in connection with the fossil diagenesis,
conserving the large and resistant tests, destroying the
small and fragile ones. A size sorting effect also takes
place.

Glauconitization of foraminiferids is frequent, and
is confirmed by X-ray diffraction analysis. Glau-
conite fills the chambers and pores. Only rare speci-
mens are filled with pyrite.

On the basis of these facts, the major part of the
species are considered to be par-autochthonous. On
the other hand, it is thought that Miliammina fusca,
Oolina melo, Lagena laevis f. perlucida and Lagena
sp. probably are allochthonous. This will be discussed
later (see pages 17).

The relationship between numbers of species and per
cent dominance gives additional criteria for the analy-
sis of microfaunal mixing. It shows the relationship
found, in each sample, between faunal variability and
faunal dominance. In the Miocene associations found
at 122.10—128.00 m stay within the normal variation
range of the curve established by Warrton (1964,
fig. 26), which is typical for autochthonous assembla-
ges.

3. POSSIBLE DEPOSITIONAL ENVIRONMENTS

In order to reduce the range of environmental pos-
sibilities the method proposed by Murray (1973) is
applied, taking also into consideration the limitations
indicated by Murray (1976). The summary diagram
for the a index and the summary triangular plot are
used (Murray, 1973, figs. 32, 101 and 102). The «
index is very useful because it clearly restricts the
environmental posibilities. The triangular plot,
however, is not so obvious because the samples exami-
ned lie near the Rotaliina corner.

Synthesising both criteria, the environmental pos-
sibilities are reduced to: normal marine shelf seas,
normal marine lagoons, and hypersaline lagoons.

In order to specify the environment the data given
by the microfauna is used, in relation to the following
factors:

a) Salinity. The « index values from 5 to 8
eliminate hypersaline environments.

The presence of the genus Ampbhistegina is most
important. All finds known from the Present come
from waters of normal marine salinity, or slight
hypersality (Larsen, 1976; Murray, 1973). The spe-
cies Ampbhistegina lessonii (and/or Amphistegina
radiata) was also found on the atlantic South Ameri-
can coast in normal marine environments (BOLTOVSKOY
& Lena, 1966; CLoss & BARBERENA, 1960b; Tınoco,
1965/66).

According to Murray (1973) the following genera
contained in the analysed microfauna are characteri-
stic for normal marine environments: Ampbistegina,
Cassidulina, Cibicides, Buccella, Nonionella, and
Textularia. The fauna also includes the genera Quin-
queloculina and Miliolinella (Miliolidae) which are
characteristic for salinities above 32 per mil. "The per
cent incidence of these genera are:

Depth/m 122 124 125

124 125 128

Normal marine genera 75 %/o 88 0/0 84 0/0
Miliolidae 7% 50/0 40/0
82 0/0 93 0/o 88 0/0

The remaining genera can be found in normal ma-
rine conditions and also in hyper and hyposaline
waters.

The presence of the bryozoan Discoporella gives an
additional argument for the existence of a normal
marine environment. Today this genus is virtually
restricted to sands of the continental shelf (DrıscoL,
Gısson & MiTcHELL, 1971).

In summary, the faunas studied indicate normal
marine salinities. Therefore Miliammina fusca is con-
sidered probably to be an allochthonous species,
because it proliferated in hyper and hyposaline
environments.

b) Temperature. Ampbistegina is also im-
portant for determination of ancient temperatures
during the Miocene, as was shown by HORNIBROOK
(1968) and Toop (1976).

There are two points of view concerning the
tolerance of Amphistegina to water temperature:

Murray (1973, p. 183—185) shows that Amphiste-
gina is a stenothermal genus. All occurences in the
oceans are encompassed by the 25°C surface-water
isotherms for the southern and northern summers.
The available information indicates that the critical
temperature needed by Ampbistegina for its reproduc-
tion seems to be close to 25°C. This genus can colo-
nize areas where the water temperature is lower, but
as it cannot reproduce, its colonization is temporary.

Larsen (1976, p. 18, 24) considers Amphistegina to
be a tropical to warm subtropical genus. Its distribu-

tion can be limited by the 14° C winter isotherm of
surface-water.

Murray and Larsen used different criteria for their
interpretation of the range of geographical distribu-
tion of Ampbhistegina. MURRAY considers the capacity
of reproduction as the basic criterion. LARSEN cited
laboratory experiments about the capacity of move-
ment of different species of Amphistegina to suport his
view.

At the present time, distribution of Ampbhistegina
along the South American atlantic area confirms
MurrAY’s point of view. Today Ampbistegina is
only found north of 23° S latitude (BoLTovskoy,
1961, 1965, 1976; BoLTovskoyY & LEnA, 1966; BoL-
TOVSKOY & WRIGHT, 1976; CLoss X BARBERENA, 1960b;
Rısas, 1971; RoprıGuzs, 1968, 1971, 1972; 'Tınoco,
1965/66, 1971, 1972). It is a region of tropical
warm waters, with mean annual temperatures higher
than 24° C (BarechH, 1954). The surface-water tem-
peratures range between 24°C in February and
21° C in August (BoLTovskor, 1976, fig. 2).

Furthermore, adult and juvenile tests of Amphiste-
gina gibbosa have been found in Chuy N° 364. This
indicates the existence of high enough temperatures
that the whole reproductive cycle of this species could
be completed.

Cibicides aknerianus and Cibicides “psendounge-
rianus” are the dominant species between 122.10 to
128.00 m. Cibicides aknerianus is a cosmopolitan
species (BoLTovskoY, 1970a). The present geographi-
cal range covers warm and cold water bodies. This
species is frequent along the coasts of the State of
Pernambuco (BoLTovskoy & LEnA, 1966) and in the
Malvin or Falkland Islands area (BoLrovskov, 1965,
1970a; BoLrovskoyv & WRIGHT, 1976). Cibicides
“psendoungerianus” is considered to be actually a
common form on the South Brazilian and Uruguayan
shelf seas, between 21—35° S latitudes. It is also
frequent in the littoral zone of Pernambuco (BoL-
TOVSKOY & LENA, 1966).

If we exclude the extinct forms, and the living ones
such as Miliammina fusca and Cassidulina subglobosa,
the remaining species belong to the present warm
water faunas of the South American atlantic shelf
areas. Most of them also live south of this parallel.

Rare specimens of Buccella peruviana, s. |. were
found in the Miocene assemblages. The highest per
cent occurence is 1,5/o in the 125.40— 128.00 m level.
This species is a characteristic living form in cold
water bodies. Today its northermost occurence lies at
21°46'S latitude (BoLrovskoy, 1961, p. 257, 338).
This species was also found in the Cabo Frio area
(Tınoco, 1955). Cassidulina subglobosa is considered
to be an indicator of the Malvinian current (PEREIRA,
1969).

It must be concluded that the analized microfaunas

indicate warm water temperatures equivalent to those
existing today in the Cabo Frio area. It must also be
pointed out that during the Miocene the world mean
annual temperatures were undoubtedly higher than
today (BRAsIER, 1975b; SCHWARZBACH, 1974).

c) Bathymetry. Ampbhistegina is also useful
for bathymetric zonation. Different opinions are
given in reference to its depth range. According to
Murray (1973) Ampbhistegina possesses excellent relia-
bility as a bathymetric indicator. All reported finds
of this genus came from shallow waters (5—20 m,
inner shelf). Borrovskoy & LEnA (1966) and BoL-
TOVSKOY & WRIGHT (1976) agreed with this point of
In contrast other evidence is given that
indicates that Amphistegina lived at somewhat greater
depth (Banpy, 1956, 1964; BrAsıER, 1975a; PoaG &
SIDNER, 1976; Tınoco, 1972). Additional data from
the literature is summarized by LArsen (1976, p. 18).

These apparent contradictions have been recently
explained. Toop (1976) concluded that different
species of Amphistegina have their major concentra-
tions in different environments and different depths.
Furthermore, there is a relationship between the shape
of the tests of Amphistegina and the environment
where it lives. Probably fragile and complanate tests
imply deeper water more distant from shore, than the
thick, heavy walled tests that would be more suitable
to withstand the turbulence. Larsen (1976, fig. 3)
found that different species of Ampbhistegina live
within distinct depth intervals. Shallow water spe-
cies are thick shelled (small diameter/thickness ratio)
while the deeper species are thin shelled. General-
izing, there is a variation from almost globular shal-
low species to almost plate-like depth species. This
means that there is a general tendency towards increa-
sing shape index with increasing depth (Larsen, 1976,
table 1). It is suggested that this is the consequence of
a relationship between the surface area to the amount
of incoming light, because this genus is dependant on
symbionts.

view.

The adult tests of Ampbhistegina found in Chuy
N’ 364 are thick or globular shaped and heavy wal-
led. 'That means that they belong to the shallow
water species, i. e. a shallow environment.

Other genera which are useful for bathymetric
zonation are Elphidium and Quinqueloculina. Sev-
eral Elphidium species are characteristic for shallow
environments, particularly Elphidium discoidale.
Quinqueloculina is regularly found on the inner shelf
(Banpy, 1964; BoLTovskoy, 1965; BoLTOvVskoyY &
WRIGHT, 1976; MurRAY, 1973; WALToN, 1964). The
remaining genera and/or species have a low reliability
as far as depth zonation goes.

Moreover the foraminiferal fauna is different from
that of the outer shelf. In the Miocene assemblages
planktonic foraminiferids are absent. The benthic

genera which are typically found in greater depths,
such as Nodosaria, Uvigerina, Fissurina, Gyroidina,
Lenticulina, Lagena, are nearly completely absent. In
their diversity the investigated associations are also
different from those of the outer continental shelf.

Summarizing, the assemblages indicate nearshore
shelf environments.

d) Substrate. The facies found between 122.10
— 133.00 m are made up of sandy deposits that were
accumulated during a progressive overlap.

Lists were made that established relationships
between the substrate type and the distributional
pattern of certain genera and/or species of benthic
foraminiferids (BoLTovskoy, 1965; BoLTovskoyv &
WRIGHT, 1976; Murray, 1973). Sometimes the data
offered are contradictory. This is also valid for Am-
phistegina (LARsEn, 1976, p. 17, 18; MurrAY, p. 185,
248). This difference originates in the fact that many
genera and/or species do not possess a strict depen-
ce on a certain facies type. Deposits formed by
unconsolided sands are characterized by a lack of or
low vegetation growth. This fact could partially
explain the absence of Peneroplis, Marginopora, Am-
phisorus, and other common genera that actually
develop in the warm water zone of the South Ameri-
can atlantic coast. These genera grow on sea flora,
especially seagrasses (BRASIER, 1975b; MuRRAY, 1973).
This fact could also explain the low abundance of
other Miliolids. It must be noted that sea grasses are
today, significantly, absent from the major part of the
South American coasts, except the tropical Atlantic
region and a few finds from Chile and Argentina.
This fact is related to the evolution of the seagrass
communities in this region (BRASIER, 1975b; HAarToG,
1970).

According to MurraY (1973) the genera Oolina and
Lagena live on muddy sediments. Therefore Oolina
melo, Lagena laevis f. perlucida and Lagena sp. could
be considered as allochthonous forms.

4. PALEOECOLOGICAL RESULTS SUPPORTED
BY FORAMINIFERAL ASSOCIATIONS

The foraminiferids indicate a normal marine shal-
low environment with warm waters. The substrate
probably had no sea flora cover.

No studies have been made of living foraminiferids
from normal marine lagoons in the South American
tropical region that could be used to establish rela-
tionships. Using available information, a normal
marine lagoon as a possible depositional environment
is rejected. The present living foraminiferal assem-
blages found in this type of lagoon differ clearly from
the associations found in the Chuy drilling (see
Murray, 1973, table 12).

The characteristics of the foraminiferal assemblages
of Chuy N° 364 are similar to the idealized depth

zonation on a continental shelf gived by MurRAY
(1973, p. 168). This shows a nearshore shelf environ-
ment, particularly within the turbulence zone. The
foraminiferal assemblage possess a low diversity
(«a = 5—8) and the triangular plot show an evident
predominance of Rotaliina (fig. 2). The values are
typical for this idealized depth zone. The value
number of the faunal variability and the faunal
dominance also indicates the same environment, ac-
cording to WALTon’s (1964) method.

This environment is related to a nearshore sedimen-
tation zone. The assemblages are par-autochthonous
and distinctive for high energy moving waters. A
rolling of the microfossils during life is evident. The
empty tests can also be worn down by rolling after
death. Subsequently glauconitization took place.
This type of fossilization can be explained at least in
the following ways:

a) A fraction of the test were transported to an
adjacent area, where somewhat lower energy condi-
tions exist. The test accumulated in a basin or a pan
situated on the shelf sea. This acted as a trap, where
a great number of tests, larger fossil debris, and
organic matter was accumulated. This process was
described by WHATLEY & Waur (1969). In this situa-
tion slight reduction conditions appear, which produce
the glauconitization.

b) Weak influence of hyposaline waters or fluviatile
sediments led to slight anaerobic conditions. In this
situation glauconitization took place as described by
SEIGLE (1970) in the Yabucoa Bay. Large fluviatile
SELLEY (1976,
p. 78) points out that glauconite occurs in ancient
sediments of marine origin.

influences prevent glauconitization.

In high energy waters a reworking of the foramini-
ferids took place. These reworked tests are mostly
glauconitized and subsequently rolled. This foramini-
feral preservation is typical for this kind of deposi-
tional environment.

The following events occured during a transgres-
sion. Information found at the 133.00— 130.00 m level
of the sample indicate the beginning of the transgres-
sion. The greatest water depth was reached at the
124.00—122.10 m level of core sample. Here the
foraminiferal assemblage has its major diversity and
abundance. The sandy deposits contain the finest
grain sizes, and are well sorted.

The foraminiferal assemblages also indicate the
existence of a transgressive sequence. This is shown
by an increase in the faunal variability, and a decrease
in the faunal dominance (fig. 2). Both concepts are
used according to WALToN’s (1964) criteria.

The fossil assemblages found between 122.10—
113.00 m contain only molluscan fragments and
barnacle plates. No microfossils are present. This
sequence may have been deposited during a regression.

VEQUATERNARY

A. General considerations and previous
works on foraminiferal microfaunas

During the Quaternary only local transgressions
took place in the South American atlantic borderland.
This fact explains the low number of papers referring
to Quaternary foraminiferids in this zone.

In Uruguay studies were made only by Cross
(1966a) and Cross & MaDEırA (1968a). Brief refer-
ences are also given by BERTELS & MADEIRA-FALCETTA
(1977) and Cross (1970).

The present knowledge of the Quaternary fo-
raminiferal associations found in Brazil is summarized
by BERTELS & MADEIRA-FALCETTA (1977). Quater-
nary sequences of bore-holes drilled in the Pelotas
Basin contain foraminiferal associations characterized
by low diversities. Only 15 benthic and a single
planktonic species were found (Cross, 1970).

In Argentina the exposures show littoral deposits,
lying subparallel to the shore, from Buenos Aires to

PUEBLO SAN LUIS (WELL) N°® 1072/1

Well location: Pueblo San Luis, Rocha County
(Lat. 33°36° S, Long. 53°43’ W). Length of drill column:
42 m.

the southernpart of the country. The foraminiferal
assemblages also have low diversities (BERTELS, 1975;
BERTELS & MADEIRA-FALCETTA, 1977; BOLTOVSKOY,
1959b; DE CarLı & Farınarı, 1975; MALuMIAn, 1970).

B. Distribution of the microfossils and
macrofossils

The distribution of the associations found in each
bore-hole and outcrop is given in Tables III—XVI.
The geographic location of the wells and exposures,
and the identified stratigraphic units, are also present-
ed. Complete lithological profiles of the bore-holes
are not given for the following reasons: 1) previous
publication, 2) no autorization was obtained for the
publication of the remaining geological sections.

Paleontology: Distribution of fossils is shown in
Table II.

Depth/m

TABLE III
Faunal distribution in San Luis N° 1072/1

21 25 28 29 30
25 28 29 30 32

FORAMINIFERA

Ammonia beccarü var. parkinsoniana o

Elphidium discoidale
Elphidium gr. excavatum
Elphidium galvestonense
Elphidium gunteri
Elphidium div. spp. indet.
BIVALVIA
Pitar (P.) rostrata

debris
GASTROPODA
Littoridina sp.

debris
OSTRACODA

BALANOMORPHA
barnacle plates

PLANTAE
debris

References: Numbers of foraminiferids:

. (il)
NE 10)

Lithostratigraphic units: These are estab-
lished using the criteria indicated in Chapter VII. The
following units were identified: Raigön Formation (42—

36m), Chuy (sensu lato) I (36—21 m), Libertad I (21—
17 m), Chuy (sensu lato) II (17—6 m), and Libertad II
(6-0 m).

CHUY (WELL) N? 364

Well location and previous studies: Distribution of Quaternary micro-
See Chapter V—A and V—B. and macrofauna: isindicated in Table IV.
TABLE IV

Faunal distribution inChuy N° 364

Depth/m 2 30 35 40
7 35 40 45

FORAMINIFERA

Ammonia beccariü var.
parkinsoniana

Bolivina striatula

Bolivina sp.

Buccella peruviana, s. |.

Bulimina cf. affınis

Buliminella elegantissima =

Cibicides “psendoungarianus”

Discorbis sp.?

Elphidium discoidale

Elphidium gr. excavatum

Elphidium gunteri

Elphidium sp. B .

Elphidium div. spp. indet. = oo Se

Fissurina laevigata .
Fissurina sp. .
Quinqueloculina sp.

(+)
BIVALVIA

Erodona mactroides

debris

OSTRACODA

Argilloecia
Bensonia
Callistocythere
Cyprideis
Cytherella
Cytheropteron x
Harmanites? x

BALANOMORPHA
Balanus sp. (barnacle plates) x x x

ECHINOIDEA-IRREGULARIA
spines x

PLANTAE
pollen x x

HMMM

(+) Cross & MapeırA (1968a) also recorded the presen-
ce of Elphidium galvestonense between 54.20—57.60 m.

References: Numbers of foraminiferids: e (1)
ei)
(21-40)

L___] (81—160)

45 54 57 60
50 57 60 63

MRMHMH

ee (2-5)
— — (11—20)

EEE (> 160)

63
66

Stratigraphy: See Chapter VII.

COSTA AZUL (WELL) N° 1060/1 54°09’ W) and attained the depth of 66 m. The lithofacies
well loeasion andprevioustecuchlen: of this well were described by Da SırvA (1975).

This bore-hole was drilled in Balneario Costa Azul, in the Paleontology: The distribution of the micro- and
property of O.S.E., Rocha County (Lat. 34°37’ S, Long. macrofauna is shown in Table V.

TABLE V
Faunal distribution in Costa Azul N® 1060/1

Depth/m 19 21 25 28
21 25 28 32

FORAMINIFERA

Ammonia beccari var. parkinsoniana zel®l .. . .
Buccella peruviana, s. |. Ki
Buliminella elegantissima —
Cibicides aknerianus .
Discorbis peruvianus . .
Discorbis gr. vilardeboanus ..
Discorbis williamsoni f. praegeri u .
Discorbis gr. sp. “A” .
Discorbis div. spp. indet.
Elphidium discoidale ——
Elphidium gr. excavatum _
Elphidium gunteri ..
Elphidium div. spp. indet. ..
Guttulina problema .
Oolina melo .
Poroeponides lateralis .
Pyrgo nasuta .
Pyrgo ringens patagonica .
Quinqueloculina seminulum .
Quinqueloculina sp. .
Rosalina sp. ? .

Textularia sp.

BIVALVIA

Amiantis purpurata
Brachidontes (B.) rodriguezi
Corbula caribaea

Corbula lyoni

Corbula sp.

Crassinella cf. maldonadoensis
Mactra patagonica

Mactra sp.

Mytilus sp.

Ostrea sp.

Plicatula cf. gibbosa x

TABLE V (continued)
Faunal distribution in Costa Azul N° 1060/1

Depth/m 19 21 25 28
21 25 28 32
GASTROPODA
Caecum sp. x:
Crepidula aculeata x
Epitonium aff. unifasciatum x
Halistylus cf. columna x x
Ocenebra cala x
Olivella (O.) cf. tehnelcha x:
OSTRACODA x x x
BALANOMORPHA
Balanus sp. (barnacle plates x x x
MALACOSTRACA
cheliped x
BRYOZOA >
ECHINOIDEA-CLYPEASTEROIDEA
Mellita sp. x
ECHINOIDEA-IRREGULARIA
spines x x:
References: Numbers of foraminiferids: .(i) oo (2-5)
(6-10) en ig=20)

(21—40) UDO (41—80)

LA PALOMA (WELL) N° 482/1

Well location and previous studies: La
Paloma City, Rocha County (Lat. 34°39’ S, Long. 54°09’ W),
in the Parque Andrecito. Length of drill column: 73.30 m.
The lithofacies were described by Da Sırva (1975) and

SCARABINO (1974).

Depth/m

FORAMINIFERA

Ammonia beccari var. parkinsoniana
Buccella pernviana, s.].

Discorbis williamsoni f. praegeri
Poroeponides lateralis
Quinqueloculina sp.

BIVALVIA

Abra uruguayensis
Amiantis purpurata
Brachidontes (B.) rodriguezi
Cardita (C.) plata

Chlamys tehnelcha
Crassinella cf. guadalupensis
Crassinella maldonadoensis
Glycymeris longior

Mactra isabelleana

Mactra cf. marplatensis
Mytilus platensis

Ostrea equestris

Ostrea puelchana

Ostrea sp.

Sphenia hatcheri

Strigilla (R.) cf. rombergii

GASTROPODA

Anachis isabellei

Anachis moleculina
Caecum (Caecum) sp.
Calliostoma sp.?
Crepidula aculeata
Crepidula protea
Halistylus columna
Odostomia (C.) aff. jadisi
Odostomia sp.?

Olivella (O.) tehnelcha
Tegula (A.) cf. patagonica
Turbonilla (Bartschella) sp.
Turbonilla (Strioturbonilla) sp.
Turbonilla sp.

Urosalpinx rushi
Vitrinellidae?

OSTRACODA

BALANOMORPHA
Balanus sp. (barnacle plates)

BRYOZOA
SERPULIDAE

PLANTAE
debris

References: Numbers of foraminiferids:

Paleontology: The first paleontological approach
of the well was given by Scarasıno (1974), who mainly
studied the macro-molluscs, which are marked with “S” in
Table VI. The disintegration of the drill cuttings with
HsO, for micropaleontological porposes gave scarce fora-
miniferids. Small and juvenile molluscs were also found,
which are marked with “x” in Table VI. The fossils are
mostly abraded and transported.

TABLE VI
Faunal distribution in La Paloma N° 482/1

39
5.8

5.8 7.8 9.09,5.210.07 410.97212:97 13.9
7.8 9.0 19:07 7319.97 12:9, 713.97 13.0

.o
x:
S
x x
x x
S S
x
x
S S x x
S S Ss x
x
S x
S S 5 x
S S
x x x x
x
x x
x
x
EX
S x
x S
S S x
x
x
x
x x
x
x
x
x x
x
x x x x
S
x
x

e (1) eo (2-5)

PUERTO LA PALOMA (WELL) N® 449/11

Well location and previous studies: La
Paloma, Rocha County (Lat. 34°39’ S, Long. 54°09' W).
The bore-hole was drilled in the Puerto Nuevo area. Length
of drill column: 8.50 m. Da Sırva (1975) and SCARABINO
(1974) described the lithofacies.

Paleontology: The macro-molluscs were described
by Scarasıno (1974), and mare marked with “S” in
Table VII. Micropaleontological study allowed identifica-

tion of foraminiferids and micro-molluscs. The latter are
marked in Table VII with “x”. "The microfossils of the
7.50—8.00 m drill cutting level were found in 140 cm? of
sediment. The tests were separated out by flotation in
CCl,. In this way more information about diversity and
faunal spectrum is obtained. The microfauna of the
remaining drill cutting was prepared in H,O, using
35—40 cm? of sediment.

TABLE VII
Faunal distribution nPuertoLaPaloma N? 449/11

Depth/m 0.0 0.5
0.5 2.5

FORAMINIFERA

Ammonia beccarü var. parkinsoniana

Baggina sp.?

Buccella peruviana, s. |. — oe.

Cibicides aknerianus

Dentalina communis

Discorbis pernvianus .
Discorbis williamsoni f. praegeri
Discorbis sp.

Elphidium discoidale

Elphidium gr. excavatum
Elphidium galvestonense
Elphidium gunteri .
Elphidium div. spp. indet.
Flintinella sp.

Guttulina plancii
Miliolinella subrotunda
Miliolinella sp.

Oolina melo
Poroeponides lateralis
Pyrgo nasuta

Pyrgo ringens patagonica .
Pyrgo sp.

Quinqueloculina angulata f. typica
Quinqueloculina atlantica
Quinqueloculina aff. frigida
Quinqueloculina intricata
Quinqueloculina seminulum
Quinqueloculina sp. D
Quinqueloculina sp. E
Quingueloculina div. spp. inder.
Textularia gramen

Textularia sp. B

References: Numbers of foraminiferids:

2:5 35 4.5 5.0 6:5 Re) 8.0
3.5 4.5 5.0 6.5 7:5 8.0 8.5
.o .. . n—
®
ee PET
..
o
.. DO
. ze
°
.. ® .. o .o o
.o
}
. o ..
.. .o .
.
o
} ® . L}
oo .o
o
.. -- -- -- LJ] I
}
. .. .. .
..
®
. ..
L}
o
. .. .. ® vo —— [
®
.. —_ o oo = .
.
®
. (1) .. (2-5)
— (6-10) eg (1-00)
(21—40) F=] (81160)

BEE (> 160)

TABLE VII
Faunal distribution nPuertoLaPaloma N? 449/11
(continued)

Depth/m 0.0 0.5 2.5 3.5 4.5 5.0 6.5 DE)
0.5 2.5 Sm 4.5 5.0 6.5 75 8.0

BIVALVIA

Brachidontes (B.) rodriguezi S S S S x
Cardita (C.) plata x

Crassinella guadalupensis

Crassinella maldonadoensis >
Diplodonta vilardeboana

Glycymeris longior S
Mactra isabelleana S S
Mactra marplatensis

Mactra sp. x

Mytilus platensis S S
Ostrea equestris? S

Ostrea puelchana S S S Ss
Ostrea sp. x

Petricola sp. x

Pleuromeris sanmartini x

Sphenia hatcheri x

GASTROPODA

Acmaea subrugosa S S S Ss
Buccinanops sp. x

Caecum (Brochina) sp. x x
Caecum sp. x x

Crepidula aculeata S x S S S S
Crepidula protea S

Diodora patagonica S S
Epitonium sp. 5

Halistylus columna S x x x S 5 x
Littoridina australis S

Ocenebra cala £ x S x

Olivella (O.) puelcha S S S

Olivella (O.) tehnelcha S

Tegula (A.) patagonica S S
Triphora sp. x Ss

Turbonilla sp. x

Urosalpinx rushi S S x S

POLYPLACOPHORA

Chaetopleura isabellei Ss
Chaetopleura sp. x

OSTRACODA x x x X x x x x
BALANOMORPHA

Balanus sp. (barnacle plates) x x x x x x x x

BRYOZOA x x x x x x >.<
ECHINOIDEA-IRREGULARIA

spines x x

ALGAE >= 5% x x x X x x

nunMa
Ce u 077
nu

HMWnM
[07]
un
(07)

LA CORONILLA (WELL) N°® 811
(Lat. 33°54’ S, Long. 53°31’ W). Unfossiliferous.

OCEANO ATLÄNTICO (WELL) N° 521/1
(Lat. 34°20’ S, Long. 53°48’ W). Unfossiliferous.

18 DE JULIO (WELL) N° 801/1
(Lat. 33°41’ S, Long. 53°33’ W). Unfossiliferous.

LAGUNA DEL SAUCE (WELL) N° 861/1

Located in the property of I.G.G.A.M. Uruguay; 8 km
north of the km. 119.5 of the national road N°® 5, in
Maldonado County. Unfossiliferous.

PIRIAPOLIS (WELL) N® 431/7

Well location and previous studies: Pi-
riäpolis City, Maldonado County (Lat. 34°53’ S, Long.
55°16’ W), in the Jardin de los Angeles district. Length of
drill column: 23 m. Mayria DE ScArABıno (1974) descri-
bed the lithofacies and molluscs of this bore-hole (Table
VIII). Littoridina australis was shown to be the dominant
species between 5.50—7.00 m.

Paleontology : No foraminiferids were found.

TABLE VIII
Faunal distribution in Piriäpolis N® 431/7

Depth/m 515 7.0

7.0 9.0
BIVALVIA
Anomalocardia brasiliana x x
Ostrea puelchana x
GASTROPODA
Littoridina australis x x
OSTRACODA x

SALINAS (WELL) N° 1034/1

Welllocation and previous studies: $a-
linas, Canelones County (Lat. 34°46’ S, Long. 55°49’ W),
in the place of the O.S.E. reservoir tank. Length of drill
column: 72.70 m. The lithofacies of this bore-hole were
studied by Da Sırva (1975).

Paleontology: The
found is shown in Table IX.

distribution of the fossils

TABLE IX
Faunal distribution in Salinas N°® 1034/1

Depth/m 28 31 32 34 37
31 32 34 37. 39

FORAMINIFERA
Ammonia beccarii var. parkinsoniana .. u ..
Bolivina striatula . _— .
Bolivina div. spp. indet. . .. _
Buccella peruviana, s.]. — ..
Buliminella elegantissima .. .. OO = ..
Cibicides aknerianus ..
Discorbis sp. .
Elphidium discoidale .. .. Blele .. ..
Elphidium gunteri .
Elphidium div. spp. indet. .. .. _— _ ..
Fissurina laevigata ..
Lagena laevis f. perlucida .
Lenticulina limbosa .
Nonionella atlantica ..
Nonion tisburyensis ..
Pyrgo nasuta ..
Pyrgo sp. . .
Reophax artica .
BIVALVIA

debris x x x x x
OSTRACODA x x x x
BALANOMORPHA
Balanus sp. (barnacle plates) x
ECHINOIDEA-IRREGULARIA

spines x
References: Numbers of foraminiferids: . (1) ee (2-5)

(6-10) el 20)

SAN JOSE DE CARRASCO (WELL) N® 442/1

Well location and previous studies:
San Jose de Carrasco, Canelones County (Lat. 34°51’ S,
Long. 55°58’ W). Length of drill column: 73 m. Mayria
DE ScArABINO (1974) described the lithofacies and the mol-

luscs belonging to the macrofauna.

These are marked on

Table X with “MS”. The micropaleontological study allow
the identification of foraminiferids; juvenile and micro-
molluscs. They are marked in Table X with “x”.

TABLE X
Faunal distribution inSan Jose de Carrasco N? 442/1

Depth/m 11 13 17 18
13 17 18 19
FORAMINIFERA
Ammonia beccari var. parkinsoniana . .. _——
Bolivina striatula .
Bolivina sp. . °.o
Buccella peruviana, s. ]. .. elle]
Buliminella elegantissima . ..
Discorbis williamsoni f. praegeri
Discorbis sp.
Elphidium discoidale .. — _—
Elphidium cf. discoidale .
Elphidium galvestonense ..
Elphidium div. spp. indet . ..
Miliolinella sp. o
Poroeponides lateralis . . °..
Quinqueloculina div. spp. indet. .. _
Triloculina sp. ..
BIVALVIA
Chlamys cf. tehnelcha MS
Chlamys sp. x
Mactra isabelleana MS MS MS
Mactra marplatensis x
Mactra sp. x x
Ostrea equestris MS MS MS
Ostrea pnelchana MS MS
Ostrea sp. x
Pitar (P.) cf. rostrata MS
debris MS MS MS MS
GASTROPODA
Anachis sp.? x
Buccinanops gradatum MS
Crepidula aculeata MS
debris x x x
OSTRACODA 5
BALANOMORPHA
Balanus sp. (barnacle plates) x x x x
BRYOZOA X x x
PLANTAE
debris x
References: Numbers of foraminiferids: .(l)
=. 676)

19 21
21 23
MS
x
MS
x
x
.o (2—5)
— — (11—20)
ODE] (41-80)

ARENERAS CALCAGNO

Location and previous studies: This ex-
posure is situated in Avenida Calcagno, 600 m, SE of the
Camino Carrasco, near Arroyo Carrasco, Canelones Coun-
ty (Lat. 34°52’ S, Long. 56°03’ W). The molluscs of this

outcrop were described by Fıcuziras (1962, 1967, 1973) and
DE Mara (1947), and were assigned to the Vizcaino For-
mation. The foraminiferids of this outcrop were studied by
SıcarDı (1969), as shown in Table XI.

TABLE XI
Faunal distribution in Areneras Calcagno

Dominant species: Elphidium discoidale,

Buccella peruviana, s. |.

Frequent species: Ammonia beccarii var. parkin-

soniana,

Discorbis williamsoni f. praegeri,

In decreasing frequency were also reported:
Buliminella elegantissima, Bolivina striatula, Poroeponi-
des lateralis, Qrinqueloculina seminulum, Oolina costata,
Pyrgo nasuta, Pyrgo ringens, Lagena laevis and Nonio-
nella sp. Fragmentary tests of Miliolidae and Nonionidae

were also reported.

PARQUE LECOCQ

Location and previous studies: This out-
crop is situated in the Zoolögico Municipal, in Parque Le-
cocq, Montevideo County (Lat. 34°47’ S, Long. 56°10’ W).
Da SırvA (1975) described the lithofacies and stratigraphy
of this locality. Exposures of similar characteristics were

described in the same area by CARDELLINO & FERRANDO
(1965, 1969). "The microfaunas found in 80 cm? of sedi-
ment from each sample are shown in Table XII. The tests
were separated in CC],.

TABLE XII
Faunal destribution in Parque Lecocgq

Depth/m below surface
scooped out by shovel 0.3 0.5

0.6 0.7 0.9 1.0 1.1 122

FORAMINIFERA

Ammonia beccarii var. parkinsoniana D .
Bolivina compacta

Bolivina cf. lomitensis

Bolivina cf. variabilis

Bolivina sp.

Discorbis pernvianus

Discorbis gr. vilardeboanus

Discorbis sp.

Elphidium discoidale ..
Elphidium galvestonense

Elphidium gunteri .
Elphidium div. spp. indet.

OSTRACODA x

BALANOMORPHA
Balanus sp. (barnacle plates)

References: Numbers of foraminiferids:

Ze 10)

° (1) eo (2—5)
Sri 0)

(21—40) UDO] (41-80)

The faunal spectrum of the molluscs is as follows:

BIVALVIA: Anomalocardia brasiliana, Brachidontes (H.)
darwinianus mulleri, Corbula caribaea, Corbula patago-
nica, Erodona mactroides, Mactra isabelleana, Mytilus
platensis, Ostrea cf. equestris, Ostrea puelchana, Ostrea
sp., Tagelus plebeins.

GASTROPODA: Acmaea subrugosa, Acteocina sp., Ana-
chis isabellei, Anachis paessleri, Austroborus Intescens,
Buccinanops globulosum, Crepidula acnleata, Crepidula
protea, Littoridina australis, Littoridina charruana, Odo-
stomia sp., Parodizia uruguayensis, Rissoa sp.?, Scolodon-

ta sp., Siphonaria (P.) lessoni, Triphora medinae.

Lithostratigraphic unit: Vizcaino Forma-

tion.

RINCÖON DE LA BOLSA (WELL) N° 754

Well location and previous studies:
This well was drilled in the Delta del Tigre disctrict, 193 m
to the south of the water reservoir tank, San Jose County.
Length of the drill column: 810 m. The lithofacies and stra-
tigraphy were described by Bossı (1966), CARDELLINO &
FERRANDO (1969) and Goso (1965). The following litho-
stratigraphic units were identified: Vizcaino Formation

(0—4 m); Raigön Formation (4—6 m); Fray Bentos For-
mation (6—95 m); Miguez Formation (95—801 m); Pre-
cambrian (801—810 m).

Paleontology: The disintegration of samples of
drill cuttings using H,O, only allowed the identification of
fossil assemblages in the strata belonging to the Vizcaino
Formation (Table XIII).

TABLE XIII
Faunal distribution in Rincön de la Bolsa N°® 754

Depth/m 1.5 2.8
2.8 4.0
FORAMINIFERA
Ammonia beccarii var. parkinsoniana ER _
Elphidium discoidale DODO ..
Elphidium cf. discoidale .
Elphidium gr. excavatum
Elphidium galvestonense _
Elphidium gunteri _— .
Elphidium div. spp. indet _ ..
BIVALVIA
Corbula caribaea x
Ostrea sp. x
debris x x
GASTROPODA
Littoridina sp.? x
debris x
OSTRACODA > x
BALANOMORPHA
Balanus sp. (barnacle plates) x
References: Numbers of foraminiferids:
e (1) .. (2-5)
=. (616) Sf 20)
(21—40) DUO (41-80)

Em (> 160)

JUAN LACAZE (WELL) N° 291/1

Well location and previous studies:
Juan Lacaze City, Colonia County (Lat. 34°26’ S, Long.
57°26’W). Length of drill column: 118 m. The lithofacies
and stratigraphy were described by Da Sırva (1975) and
SERRA (1943). Only shark teeth were identified between
20.70 and 21.70 m.

CARMELO (WELL) N° 245/1

Well location and previous studies:
Carmelo City, Colonia County, in the property of the Usina

de Filtraciön y Bombeo, O.S.E. (Lat. 33059’ S, 58°17' W).
Length of drill column: 45.30 m. The lithofacies and stra-
tigraphy of the bore-hole were described by Da Sırva
(1975) and SerrA (1943). The strata of the Vizcaino For-
mation are found between O0 and 19 m, and those of the
Fray Bentos Formation between 19 and 37 m.

Paleontology : Only molluscs were found, whose
distribution is shown in Table XIV. The presence of Ero-
dona mactroides in the 9 to 17 m drill cutting is given
according to SERRA (1943).

TABLE XIV
Faunal distribution in Carmelo N® 245/1

Depth/m

BIVALVIA

Brachidontes (H.) cf. darwinianus mulleri

Chione sp.

Erodona mactroides
Mactra isabelleana
Ostrea sp.

Pitar (P.) rostrata
Tagelus cf. plebeius

GASTROPODA

Littoridina australis
Littoridina charruana

BALANOMORPHA
Balanus sp. (barnacle plates)

CARMELO (WELL) N° 235

Well location and previous studies:
Carmelo City, 300 m north of Carmelo N° 245/1, Colonia
County. The lithofacies and stratigraphy were described
by Serra (1943).

0.0 7.5 9.0
7.5 9.0 17.0
x
x
x x x
x
x
x
x
x x
x x
x x

Paleontology: Fossils were found in strata of the
Vizcaino Formation, as indicated in Table XV.

TABLE XV
Faunal distribution in Carmelo N°® 235

Depth/m 1 3 % 11 15 18 23 31
7 11 15 18 23 26 37
BIVALVIA
Erodona mactroides x x x x x x x
Mytilus sp.? x
Ostrea sp. x
Tagelus cf. plebeius x x x
GASTROPODA
Littoridina australis x x x x
Littoridina sp.? x
MOLLUSCA
debris x x x x
PLANTAE
debris x

RIO URUGUAY (WELL) N° 445/1

Well location and previous studies:
In the nearness of the Rio Uruguay and Rio San Salvador
confluence, Soriano County. Length of drill column:

31.20 m. The lithofacies were studied by Da SırvA (1975).
Paleontology: The assemblages found are shown
in Table XVI.

TABLE XVI
Faunal distribution in Rio Uruguay N?° 445/1

Depth/m

BIVALVIA

Brachidontes (H.) cf. darwinianus mulleri x

Erodona mactroides
GASTROPODA
Littoridina australis

OSTRACODA

SORIANO (WELL) N° 483/2
Well location and previous studies:

Soriano City, Soriano County (Lat. 33°24’ S, Long.
58°19’ W). Length of drill column: 78 m. The lithofacies

10.0 20.0 25.0
20.0 25.0 31:2
x x x

x x
x

of this bore-hole were studied by Da SıLvA (1975).

Paleontology: See Table XVII.

TABLE XVII
Faunal distribution in Soriano N? 483/2

Depth/m 14.0
17.0
BIVALVIA
Erodona mactroides
debris x

26.0 43.0 48.0 51.0
26.7 48.0 51.0 51.5
x x x x

x x

C. Ages of the fossil assemblages

1) FORAMINIFERIDS:

Large differences were found between the micro-
faunas of the Miocene and the Quaternary in regard
to:

a)the faunal spectrum. Whereas the
Miocene assemblages indicate warm climate, the Qua-
ternary ones are typical of cold temperate waters,
being similar with the biocoenosis of this area.

b) their diversities. The Miocene assem-
blages are more diversified than the Quaternary ones.
During the Quaternary sedimentation took place in
estuarine and marginal marine environments, whereas
in the Miocene generally deeper water is indicated.

co) the preservation and coloration
of the tests (Cross, 1970 p. 35).

2) MOLLUSCS:

The faunal spectrum of the Quaternary associations
are analogous with the living ones.

In reference to age the fossil assemblages do not
allow for a more precise fine-stratigraphy within the
Quaternary strata.

3) THE AGE OF QUATERNARY FORMATIONS
WITH MARINE FOSSILS:

Chuy Formation: According to DELANEY
(1963, 1965, 1966, 1967, 1969?) the Chuy Formation
was deposited as a beach or bar deposit during the last
Pleistocene interglacial. BERTELS & MADEIRA-FALCETTA
(1977), GoXi & HorFsTETTER (1964), Goso (1972)
and Trıcarr (1972) also considers the Chuy Forma-

tion as belonging to the Pleistocene. Antön (1975)
also placed this formation in the Pleistocene, parti-
cularly in the Belgranense Stage. Cross (1970) indi-
cated a Pleistocene age, but considered a Holocene age
as possible. Holocene age is proposed by Cross &
Forrı (1971). Jost, Pınro & Loss (1972) considered
the top of the formation to probably be of lower
Holocene age, whereas Jost (1972) included this unit
in the upper Pleistocene, lower and middle Holocene.

There is a general agreement between previous
workers that the Chuy Formation was deposited
during a time of high sea level. The regional geologic
history during the upper Pleistocene and Holocene
(Chapter VI-E) shows: a) the existence of Holocene
high sea levels, b) the presence of previous transgres-
sive events. The age and extension of these Pleisto-
cene high sea level events is very controversial. On
the other hand new data shows that in many parts of
the world a widespread occurence of active sand dunes
can be observed between 18,000—16,000 y. BP in
coincidence with the peak of last glacial intensity.
New research is necessary to solve contradictions data
by C 14 dating. Taking into consideration the
available information, an upper Pleistocene
age seems to be probable for the Chuy Formation.

Vizcaino Formation (=Querandi-
na): This unit belongs to the Holocene, as is
indicated by geological and paleontological approach-
es (Bornas, 1957; Bossı et al. 1975; CALCATERRA,
1971; CARDELLINO & FERRANDO, 1969; DE MATA,
1947; FIGUEIRAS, 1961, 1962, 1967; ForTI, 1968, 1969;
GoNı & HorrstETTEr, 1964), and by radiometric
datings (Auer, 1974; DELANEY, 1967, 1969?; ÜRIEN
& Ewıng, 1974; VOGEL & LERMAN, 1969).

The above is dealt more extensively by SPRECH-
MANN (1978a).

D. Stratigraphy

In order to establish lithostratigraphic correlations,
the identification of stratigraphic units is indispen-
sable. Several handicaps are apparent in identifying
these units:

1) The cable-tool method used to drill the cores.

2) The lack of informations in establishing the
exact altitude of some bore-holes.

3) The imprecision with which some of the Tertiary
and Quaternary superficial stratigraphic units were

defined and described by their lithology.
4) In addition rapid facies changes are observed.

5) Thelack of geological maps with appropiate
scales and cross sections for the greater part of the well
region.

Classically, it is considered that the greater part of
the molluscan and foraminiferal faunas, found in the
Uruguayan Quaternary, were deposited in the Holo-
cene during a single transgressive event, the so called
“Querandina Transgression”, which was assigned to
the Vizcaino Formation. In this way a tacit time-
stratigraphic correlaction was established between
different exposures bearing fossils from the Queran-
dinense. Only few exceptions were marked: a) The
molluscan assemblages found in the ex-cementerio de
Nueva Palmira. The prevailing point of view is that
these molluscan assemblages belong to the Vizcaino
Some authors, however, have attributed
them to the Belgranense Transgression; b) the associa-
tions from the Arroyo La Palma outcrop, tentatively
attributed to the Belgranense by FıGueiras (1974); and
c) the foraminiferids found in the Quaternary strata
of Chuy N° 364 (Chapter VII). Cross (1970) pro-
posed a time-stratigraphic correlation of these strata
of Chuy N° 364 with bore-holes PJst-1-RS (Ponta
do Juncal), Cast-1-RS (Curral Alto), and Cist-1-RS
(Cassino) from the Pelotas Basin.

Formation.

For the solution of some of these questions of Qua-
ternary stratigraphy it would be very useful tool to
review the geological history of this region (Chapter
VI-E). Secondly it is indispensable to recognize and
use certain marker horizons as marker beds, to clarify
the chaotic situation existing in this area. With this
aim new ecostratigraphic correlations are proposed in
Chapter VI-G.

E. Upper Pleistocene and Holocene
history of the Rio de la Plata region

An understanding of geological evolution and de-
velopment of the Rio de la Plata area in the modern
Quaternary is necessary for biostratigraphical and
paleogeographical studies. Only data based on C 14
age dating are used.

35,000 years ago, during middle Wisconsin time
(PORTER, 1971), the shore line was situated not less than
120 m below the present level. The most probable
level has been estimated to be approximately 150 m
below present (BoLTovskoy, 1973; Cross, 1970; DE-
LANEY, 1966, 1967; Fray & EwınG, 1963; RICHARDS,
1966; RıcHARDS & BROECKER, 1963; RIıCHARDS &
Craıc, 1963).

15,300 y. BP the shore line was situated between
55 and 73 m lower than present (Auer, 1970, 1974;
BoLTovskoy, 1973; Fray & Ewıng, 1963; RICHARDS
& Craıs, 1963; ÜRIEN, 1967).

12,000 to 11,000 y. BP sea level was 110 to 140 m
below present. (Auer, 1970, 1974; BoLrovskoy, 1973;
Fray & Ewınc, 1963; RıcHARDs, 1966; RICHARDS &
Craıc, 1963; URIEN, 1967; ÜRIEN & OTTMANN, 1971).

Between 11,000 and 7,000 y.BP a transgressive
phase commenced, raising the sea level from minus
110 to 140 m to somewhat higher than the present.

The shore of 8,620 + 100 years ago can be found
18 m below ground surface. This was confirmed by
radiocarbon dating made on peats underlying sedi-
ments of the Querandina Formation from Boring 2,
in Delta of Rio Paranä near Campana, Buenos Aires
County, Argentina (Auer, 1970, 1974; VOGEL &
LERMAN, 1969).

According to URIEN & OTTMAnN (1971), the
delineation of the following episodes in the Rio de
la Plata area are possible:

1) During the culmination of the early Holocene
transgression, the waters flooded into the estuary, pen-
etrating to the site of the city Rosario (Argentina),
reaching a level 7 to 8 m higher than the present sea
shore.

2) Between 7,000 and 3,000 y. BP the advance of
the sea seems to have stabilized itself, showing only
small oscillations.. About 6,000 years ago the sea
retreated to approximately 30 m below present, and a
barrier complex formed, obstructing the estuary.
These waters then formed an enormous lagoon.

3) Afterwards the sea advanced once again back
into the Rio de la Plata estuary, but the climatic
conditions were more humid, therefore showed
increasing runoff. The marine phase was restricted to
the outer part of the estuary.

4) About 3,000 y.BP until present the sea level
tends progressively to regress, exposing the coastal
plains of today which border on the estuary.

Only few radiocarbon dates have been made for
this part of the South American atlantic coastal
region. According to Auer (1974) and VocEeL &
LERMAN (1969) some of them probably were carried
out on allochthonous shells.. There is no guarantee
that in every case the dates were corrected in relation
to contaminations, as were those of ERLENKEUSER (in:
EinsELE, HERM & SCHWARZ, 1974).

URrIEN & Ewıng (1974) stated that only the fol-
lowing evidence seems to hold: 1) The Holocene trans-
gression began at 11,000 + 500 y. BP, raising the sea
level from minus 139 m to its present level; and 2)
between 9,000 and 2,000 y.BP sea level oscillated, and
then stabilized.

Nevertheless the Holocene sea level fluctuations
described by UrıEn & OTTMann (1971) show clearly
the existence of the following events:

1) The first transgressive phase was reached and the
highest vertical rise attained i. e. penetration of marine
facies into the inner estuary.

2) A regression follows, and a barrier complex was
formed.

3) A second less extensive transgressive stage took
place.

In the inner estuary only fluvial facies existed.

4) The sea level reached its actual stand.

These succesive transgressive and regressive events,
and their amplitude are similar to the oscillation of
sea level curves reported by Auer (1974, Appendix),
EinsELE, HERM & SCHWARZ (1974, fig. 5), and EINSELE
et al. (1977). These curves are similar to other
Holocene sea level oscillations recorded from different
world regions. This is also true for the South Ameri-
can atlantic coasts, as reported in papers which based
their conclusions on radiocarbon dates (BIGARELLA,
1964; DELIBRIAS & LABOREL, 1971).

The most adequate explanation for sea level
changes, which occur during the late Quaternary in
the Rio de la Plata region, is eustasy. This explana-
tion does not reject the incidence of hydro-isostasy or
local epeirogenic movements.

At present it is not possible to correlate these
Holocene transgressive events in the Rio de la Plata,
with those reported in other regions. Reliable con-
clusions about this topic can be made only with radio-
carbon datings and field work on the Quaternary
terraces, together with an analysis of the cores from
this area. Nonetheless it is very significant that the
presence of two chronostratigraphic sequences, desig-
nated as Vizcaino 1 and Vizcaino 2 were recognized
by Goso (1965) and Bossı (1966).

F. Paleoecology

A paleoecological approach based on actualistic
method of ScHÄFER (1962) has to be supported by
recent researches, particularly those made in the same
geographical area. The studied area is related to the
Rio de la Plata estuary and its zone of influence, and
also with the Uruguayan and South Brazilian Atlantic
coasts.

1. TEIE/RIO’DE TA PLATATESTWARY

a) Physical characteristics

In the Rio de la Plata estuary, the tides are of low
amplitude. On the Uruguayan shore they may reach
60 cm, being somewhat greater on the Argentine coast,
with a 1 m mean average (OTTMANN & URIEN, 1967,
1972). The current systems in the estuary are
reported by URIEN (1967, 1972).

Records of the annual and daily water temperature
changes are given by Borrovskoy & Lena (1974a).
The highest summer mean water temperature was
27.5°C. The lowest mean water temperature for
the winter was 7°C. The daily change of the water
temperatures fluctuated between 0.3° Cand 7°C.

The value of salinities in the estuary show a net
longitudinal change, this was verified by measure-
ments made on surface and bottom waters. In the
inner estuary fresh water conditions are always
present, however in the outer zone marine salinities
are encountered. In the middle of the estuary great
fluctuation of the salinities are found. This longitu-
dinal zonation in salinity value is typical for positive
or normal estuaries. A vertical stratification also
occurs, i. e. higher the salinities are found in bottom
waters than in surface waters (ÖTTMANN & ÜRIEN,
1965a, 1965b; URIEN, 1967, 1972).

A considerable amount of suspended sediments is
carried by the estuarine waters, with average values of
150—300 mg/l. Frequently they exceed 600 mg/l
(OTTMANN & ÜRIEN, 1965a, 1966; URIEN, 1966, 1967).

The sediment distribution and bathymetry in the
estuary and in the adjacent shelf, were much analysed
in the past few years. Diverse physiographic charts
were also made (Bıscayz, 1972; OTTMANN & ÜRIEN,
1965b, 1966; URIEN, 1966, 1967, 1972; URIEN &
Ewınc, 1974; URIEN & OTTMAnN, 1971). ÜRIEN
(1972) described the sediment distribution and the
depositional environments. The actual sedimentary
pattern is mostly controlled by the estuarine environ-
ments, and correlated in a broad way with zones of
water salinities.

b. Previous work on living
foraminiferidsand thecamoebians.

A study of the thecamoebians in this estuary was
made by BorrovskoyY (1957b) and BoLrovskoy &
Lena (1974a). The foraminiferids of the Rio de la
Plata and its zone of influence were described by
BoLTovskoy (1957a, 1958, 1970a), and BoLTovskoy
& Lena (1971, 1974b). Additional references were
also given by BorLrovskoy (1954, 1959a, 1961, 1976)
and BoLrovskoy & WRIGHT (1976). The fauna from
the Arroyo Chuy was described by Cross & MADEIRA
(1962) and MaADEIRA-FAaLcETTA (1974), and of the
mouth of the Rio Santa Lucia by ScArABıno (1967).

c) Characteristics of the
foraminiferal biocoenosis.

The salinity is the controlling factor in the distribu-
tional pattern of the living foraminiferids in the Rio
de la Plata. The distribution of the foraminiferids is
correlated as well with the depositional environments
found in the estuary.

BoLTovskoy & Lena (1974b) defined three biofacies
for the living foraminiferal fauna of the Rio de la
Plata estuary (fig. 3):

1. Biofacies of Nonion tisburyensis. This
biofacies overlaps with: a) the inner-fluvial
environment, which corresponds to the upper

river delta front platform, and is characterized by the
presence of limnic conditions, and b) the outer-
fluvial environment, also called the
intermediate river (URIEn, 1972). In this
area fresh water conditions are mostly found. At
times of stormy winds, water bodies from the east can
be pushed into this area, raising the salinities. Mea-
surements indicate fluctuation in salinities ranging be-
tween 0.5 and 25 ®/oo. The most characteristic species
of this biofacies is Nonion tisburyensis. Thecamoe-
bians were also reported living (BoLTovskoY & LENA,
1971, 1974a, 1974b).

FORAMINIFERAL BIOCOENOSIS TREND
IN THE RIO DE LA PLATA

R®

CURVE OF REMANE FOR THE
FORAMINIFERAL BIOCOENOSIS

r4
3
& \.20
u
0} Ranges of
e den!
o species e
=
[2]
ge)
®
Q
®
10)

0 Salinity 35%o
Fig.3: Foraminiferal biocoenosis trend
in the Rio de la Plata (after BoLrovskoy & Lena, 1974b).
Key: 1 = Biofacies of Nonion tisburyensis, 2 = Biofacies
of “Rotalia beccarii parkinsoniana”, 3 = Biofacies of Bu-

liminella elegantissima. These biofacies overlap with the
following environments defined by URrIEn (1972): inner-
fluvial environment from line a to the west; intermediate-
fluvial environment between lines a and b; fluvio-marine
environment between lines b and c; and marine zone from
linectothe east. Curve of Remane for the fora-
miniferal biocoenosis of the Rio de la Plata
(d—.d’). Parallel lines indicate the distributional range
of living species (after BorLrovskoy & LEnAa, 1974b).

2. Biofacies of “Rotalia beccarii parkinso-
niana”. This corresponds to the fluvio-mari-
ne environment, or “Rio exterior”
(URIEN, 1967, 1972). The dominant species are Am-
monia beccarii var. parkinsoniana, which is distributed
within the whole biofacies; and Elphidium discoidale,
which prevails in the northern and southern coasts.
Miliammina fusca is present in smaller amounts.

3. Biofacies of Buliminella elegantissima.
This biofacies has boundaries which are similar with
those of the Rio de la Plata marine zone.
Buliminella elegantissima is the most frequent and
typical species, followed by Bolivina striatula.

BoLrovskoY & WRIGHT (1976, fig. 113) showed the
distributional patterns of the species which are cha-
racteristic for these biofacies in the Rio de la Plata
estuary. Epistominella exigna is the dominant species
in the shelf sea adjacent to the Biofacies of Bulimi-
nella elegantissima.

Borrovskoy & Lena (1974b) indicated that the
salinity has an additional effect on the distribution
of the living foraminiferids. The per cent fraction
occurence of the agglutinated species in the estuary
increases with the decrease of salinity. A zonation of
similar characteristics was observed in different margi-
nal marine environments and estuaries (Banpy, 1964;
BoLrovskoyY & BoLrovskoy, 1968; Cross, 1963;
Cross & MEDEIRos, 1965; ErLıson & NıcHors, 1970;
MurrAY, 1968, 1973; WALTON, 1964).

d. REMANE’s curve for the
foraminiferal biocoenosis of the
Rio de la Plata.

REMANE (1934, 1940, 1963, 1971) formulated
another criterion to reveal the relationship existing
between the water salinity and the number of species.
The most important characteristics of the curve are
present in Chapter VI-F-4.

REMAnE’s curve for foraminiferal biocoenosis of
the Rio de la Plata estuary (fig. 3, d—d’) was
plotted using the distributional ranges of living species
illustrated by BoLrovskoy & Lena (1974b, map. 17).

In Fig. 3 ReMAanE’s curve here presented was
correlated with the pattern of salinity zonation of this
estuary proposed by URrıen (1972), and with the
foraminiferal biofacies reported by BoLrovskoy &
Lena (1974b).

REMANE’s curve for living foraminiferids in the
Rio de la Plata shows clearly, that the number of
species decreases with reduction in water salinities.
This is similar with REMmANE’s curve of the living
foraminiferal faunas in the Balthic Sea (LuTzE, 1965,
fig. 28).

2. PALEOECOLOGICAL INTERPRETATION
BASED ON FORAMINIFERIDS.

The Uruguayan Quaternary foraminiferal assem-
blages provide information of the following environ-
mental factors:

a. Bathymetry: Theforaminiferids encounted
in the drill samples and outcrops are characteristic of
shallow environments (estuaries, bays, lagoons,
beaches, etc.). The water depth does not exceed 20 m
(Banpy, 1964; BoLTovskoy, 1965, 1970a, 1976; BoL-
TOVSKOY & WRIGHT, 1976; MurrAY, 1968, 1973;
WaLTton, 1964). The absence of Epistominella exigna
seems to confirm this point of view. At the Present
this is the dominant species in the open shelf areas
beyond the Rio de la Plata estuary (BoLTovskoy,
1957a; BOLTOvskoY & WRIGHT, 1976, fig. 113).

b. Temperatures: The foraminiferal associa-
tions are typical of cold-temperate water masses. The
species which indicate the influence of warm water
masses are Ammonia beccarii var. parkinsoniana,
Elphidium discoidale, Bolivina striatula and Poroepo-
nides lateralis. The cold water influence is shown
chiefly by Buccella peruviana, s. 1. (BoLrovskoy, 1954,
1965, 1970a, 1976; BoLTovskoY & WRIGHT, 1976).
This faunal spectrum is representative of the Argen-
tina Biogeographic Province, also called the “king-
dom” of Buccella pernviana, s. 1., defined for living
foraminiferal faunas. Most precisely they belong to
the northern sub-area of this biogeographical unit,
which is denoted as the North-patagonian subprovince
(BoLrovskoy, 1970a, 1976; BoLTovskoYy & WRIGHT,
1976). Other species which are frequent in the drill
cuttings, and that are characteristic of living assembla-
ges of the North-patagonian subprovince are Bulimi-
nella elegantissima and Miliolinella subrotunda.

c. Substrates: No correlations were postu-
lated in the Rio de la Plata region between the
distributional pattern of living foraminiferids and the
type of substrates. Material from the wells is inap-
propriate for this kind of study because the number of
drill cuttings where tests were found is not large
enough to establish a relationship of any kind.
Besides, changes in biotope are frequently found in
estuarine inhabitants. Their main biotope in brackish
water thus differs from that in the sea. This is parti-
cularly true for their substrate dependence (REMANE,
1971).

d. Salinities: In nearly all the estuaries the
salinity is the most important factor in determining
the extent of the foraminiferal biocoenosis. Only in
those environments, such as in the Baltic Sea (LUTZE,
1965), in which a thermohaline stratification occurs
salinity and temperature are the main factors that
control the foraminiferal distribution.

In an attempt to establish the Quaternary deposi-
tional environments, paleoecologic analysis is primarly
based on the identification of the tolerance of each
foraminiferal assemblage in relation with salinity.
Different criteria were described for recognizing
brackish foraminiferal assemblages (HıLTERMANN,
1963a, 1963b; Lurtze, 1965; MurrAY, 1968, 1973;
WALTon, 1964).

The foraminiferal biocoenosis of the Rio de la
Plata and Rio Quequen Grande were used to deter-
mine the range of the salinity tolerance for each
species found in the Quaternary well boring sequences
(BoLTovskoy, 1958, 1976; BoLTOvVskoY & BOLTOVSKOY;
1968; BoLTovskoy & Lena, 1971, 1974b; WRIGHT,
1968). In addition data from different biocoenosis
and biotopes of the South American atlantic area was
also evaluated to establish the salinity tolerance of
various species (CLoss, 1963, 1964; Cross & MADEIRA,
1962, 1967, 1968b; Cross & MEDEIRos, 1965, 1967;
Lena & L’Hoste, 1975). Likewise, the available
information about the distribution of foraminiferids
from different estuaries was used (BoLrovskoY, 1965;
BoLTovskoY & WRIGHT, 1976; ELLıson & NICHoLs,
1970; KAnE, 1967; LUTZE, 1965; MADEIRA-FALCETTA,
1974; Murray, 1968, 1973; PujJos, 1973).

Only those species found and recorded in the Uru-
guayan Pleistocene and Holocene were classified with
reference to their salinity tolerance within three Qua-
ternary biofacies:

1. Quaternary Biofacies of Buliminella
elegantissima: In this ecozone salinities are close to
marine. Those species which are capable of tolerating
small fluctuations in salinities, as well as some euryha-
line species, were included in this biofacies: Buliminel-
la elegantissima, Buccella peruviana, s. l., Poroeponi-
des lateralis, Bolivina compacta, Bolivina striatula,
Bolivina cf. lomitensis, Cibicides aknerianus, Dentali-
na communis, Discorbis pernvianus, Discorbis william-
soni f. praegeri, Fissurina laevigata, Guttulina proble-
ma, Lagena laevis f. perlucida, Lenticulina limbosa,
Miliolinella subrotunda, Nonionella atlantica, Oolina
melo, Pyrgo nasuta, Pyrgo ringens patagonica, Quin-
queloculina angulata f. typica, Quinqueloculina atlan-
tica, Quinqueloculina aff. frigida, Quinqueloculina
intricata, Quinqueloculina seminulum, Reophax artica
and Textularia gramen.

2. Quaternary Biofacies of Ammonia
beccariüi var. parkinsoniana: This overlaps the fluvio-
marine environment, and includes high and interme-
diate euryhaline species: Ammonia beccarii var. par-
kinsoniana, Elphidium discoidale, Elphidium gr. exca-
vatum, Elphidium galvestonense, Bolivina compacta,
Discorbis peruvianus, Lagena laevis f. perlucida, No-
nion tisburyensis, Oolina melo and Reophax artica.

3. Quaternary Biofacies of Nonion
tisburyensis: This biofacies contains species which are

able to dwell permanently or temporarly in fresh
waters: Nonion tisburyensis and Reophax artica.

This classification is based on studies made of the
biocoenosis and indicates the lowest salinity needed by
the species to survive, but does not indicate the lowest
allowable salinity needed for reproduction.

The most abundant species found in the drill cut-
tings which characterize the Quaternary biofacies, are
cosmopolitan. They are typical for these environ-
ments even if in different geographical areas.

The depositional environments are determinated
chiefly on the basis of the percentile occurence of the
dominant species for each biofacies, but not exclusi-
vely indicative of a single association.

A second method is a so used to evaluate the salinity
tolerance shown by the Quaternary associations. It is
based on the evaluation of the capacity of the genera
to withstand changes in salinities. The information
given by Murray (1973) is used (table XVIII).

In the wells and exposures shown in Table XVIII
foraminiferal assemblages were found that allow one
to make paleoecological interpretations. In each loca-
lity the sample with the greatest diversity was used.

3. PALEOECOLOGICAL CONCLUSIONS OF
DEPOSITIONAL ENVIRONMENTS BASED ON
BENTHIC FORAMINIFERIDS.

The analized foraminiferal assemblages indicate
shallow and cold temperate waters. Their salinity
tolerance was the greatest difference found between
assemblages.

In almost all the estuaries salinities, and other
physical characteristics (bathymetry, substrate, etc.)
gradually change in direction of its longitudinal ax;is.
The water salinities decrease in a gradational way and
a zonation is produced, which is particularly evident
in the channels. This type of zonation is herewith
called “estuarine front”.

A second latitudinal zonation is also present in the
estuarine environment, which is reflected as well in its
physical and biological characteristics. Shorewards
the limnic influence increases, asa consequence of rivers,
rivulets, marshes, lagoons and other marginal environ-
ments. This latitudinal or lateral zonation is here-
with designated the “lateral-marginal
zone ofinfluence”.

Along the longitudinal estuarine axis, the bound-
aries between facies and biofacies are gradual. In
contrast, along latitude these lateral changes are sud-
den, and therefore the environmental and faunal
limits are sharp (Erzıson & NicHots, 1970). "The pre-
sence of this double zonation makes paleoecological
reconstruction difficult.

TABLE XVII

Salinity tolerance of foraminiferal associations

Locality {3 Rotaliina Miliolina Genera Salinity
Chuy N° 364 2 100 %/o Ammonia 48 ®/o hyposaline
(40—35 m level, Bolivina 4 ®%o
drill cutting) Buliminella 27 ®/o

Elphidium 20 °/o
Costa Azul N® 1060/1 4.5 99 %/o 1% Buccella 60 ®/o slightly
(21—19 m level, Discorbis 6 °/o hyposaline
drill cutting) Ammonia 14 °/o

Elphidium 12 °/o
Puerto La Paloma N° 449/11 6 82 °/o 16 9/0 Buccella 46 °/o normal
(8.00—7.50 m level, Discorbis 3 %/o marine
drill cutting) Elphidium 7 ®/o

Poroeponides 23 %/o

Miliolinella 5 ®/o

Quinqueloculina 10 %o
Salinas N° 1034/1 * 99 %/o 1%/o Ammonia 4 °/o moderately
(34—32 m level, Bolivina 8 ®/o hyposaline
drill cutting) Buccella 4 °/o

Buliminella 32 ®/o

Elphidium 44 ®/o
Areneras Calcagno?) slightly

hyposaline

San Jose de Carrasco N° 442/1 3 81 %/0 19 %/o Ammonia 11 °/o slightly
(18—17 m level, Buccella 37 lo hyposaline
drill cutting) Elphidium 21 °o

Quinqueloculina 10 °/o

other Miliolidae 9 %/o
Parque Lecocq 2 100 °/o Ammonia 51 °/o hyposaline
(1 m below surface, Bolivina 6 ®/o
scooped out) Elphidium 40 °o
Rincön de la Bolsa N° 754 1 100 °/0 Ammonia 59 /o hyposaline

(2.30—1.50 m level,
drill cutting)

The Quaternary foraminiferal assemblages are in-
cluded in the following biofacies:

a. Quaternary Biofacies of Buliminella
elegantissima: Well La Paloma N° 449/11. Perhaps
Costa Azul N? 1060/1.

b. Transitional area between the
Quaternary Biofacies of Buliminella ele-
gantissima and Ammonia beccarii var. parkinsonia-
na: Salinas N° 1034/1, San Jose de Carrasco
N° 442/1, and Areneras Carrasco.

c. Quaternary Biofacies of Ammonia

beccarii var. parkinsoniana: Parque Lecocq, Rincön
de la Bolsa N° 754 and Chuy N° 364.

Elphidium 41 ®o

In each well or exposure only those samples carrying
the highest species diversity were considered. Nonion
tisburyensis was nearly completely absent in fora-
miniferal assemblages originating from drill cuttings.
This species characterizes a biofacies of living fora-
miniferids in the Rio de la Plata. Today this bio-
facies overlaps with the inner and intermediate-fluvial
environments. Furthermore, this biofacies presents
the highest standing crop for the estuarine biocoenosis
(BoLtovskov & LEnA, 1974b). Miliammina fusca was
not found, although it is frequent today in this bio-
facies.

The same authors have analysed the longitudinal

4) The information given by Sıcarpı (1969) about foraminiferids from this exposure is not sufficient to establish the
a index as well as the percentile occurence of the genera. However, the available data of the species composition shows

that the salinity was slightly hyposaline.

distribution in each environment of the calcareous and
arenaceous foraminiferids in the Rio de la Plata. The
per cent occurence of the arenaceous species increases
with a decrease in salinity. In the Quaternary fora-
miniferal assemblages only scarce specimenes of Tex-
tulariina were found. This absence is interpreted to
mean that the depositional environments were not
related with the inner and intermediate-fluvial estuari-
ne zone, at least in the drill samples that have supplied
foraminiferids. Nevertheless it must be pointed out,
that the “arenaceous pattern” does not always offer
total reliability, and can lead to errors in paleoecologi-
cal interpretations (LUTZE, 1965, p. 133).

The Quaternary foraminiferal assemblages indicate
an estuarine or lagoonal environment. Hyposaline,
normal marine and hypersaline marshes are rejected
on the basis of the absence of Textulariina in the
studied assemblages; and in the species composition,
because no “typical” marsch species were found
(MurrAY, 1973, p. 26—27, table 5).

Murray (1968, 1973, 1976) also pointed out the
difficulties that exist in distinguishing between estua-

RINCON DE LA BOLSA
PARQUE LECOCOQO

AN JOSE DE CARRASCO

EC ER 21 Ss

ZASIISSISSSTISIED

III

I ESSSIZZZZZ ES SI IS ISIIISLT

Fig. 4:

7
D

N = 2 B
877720 UN 92 EREURFUFLFUFFEFLFEFRFEFRFER |

Longitudinal distribution pattern of the Quaternary foraminiferal assemblages.

ries and lagunes and other marginal marine environ-
ments, using foraminiferal associations. It is thought
that almost all the foraminiferal associations were
deposited in an estuarine environment, because they
indicate a longitudinal distributional pattern. They
reveal a decrease of water salinities toward the head
of the estuary. The foraminiferal assemblages from,
La Paloma N° 449/11, Salinas N? 1034/1, San Jose
de Carrasco N° 442/1, Areneras Calcagno and Lecocq
correspond to the “estuarine front”. In contrast,
the foraminiferal assemblages from Chuy N° 364
could indicate an environment belonging to the
“lateral-marginal zone of influence”. Probably to a
lesser extent this is also valid for Costa Azul
N? 1060/1 and Rincön de la Bolsa N° 754.

In Fig. 4 the paleoecological results are shown by
the foraminiferids and are schematically illustrated.
The percentile occurence of each species is plotted in a
cumulative histogram. For every well only the
sample carrying the greatest foraminiferal diversity is
considered. Those species illustrated with dotted
signature indicate the marine influence and belong to

QUATERNARY FORAMINIFERAL ASSEMBLAGES

PUERTO LA PALOMA
COSTA AZUL

100

The
percentile occurence of species is shown in a cumulative histogram. Species illustrated with dotted
signature indicate the marine influence. Slanting lines represent areas chiefly fluvio-marine.
Key: 1 = Miliolidae, 2 = Buliminella elegantissima, 3 = Buccella peruviana, s. 1., 4 = other
species characteristic for the Quaternary Biofacies of Buliminella elegantissima, 5 = Ammonia
beccarüi var. parkinsoniana, 6 = Elphidium discoidale, 7 = other species indicating the Qua-
ternary Biofacies of Ammonia beccarii var. parkisoniana, 8 = Non indicative species.

the Quaternary Biofacies of Buliminella elegantissima.
Slanting lines represent areas chiefly fluvio-marine, and
are typical for the Quaternary Biofacies of Ammonia
beccarii var. parkinsoniana. The cumulative histo-
gram clearly shows the longitudinal zonation which is
characteristic for this estuarine environment. To-
wards the head of the estuary, the Quaternary Bio-
facies of Ammonia beccarii var. parkinsoniana gra-
dually replaces the Buliminella elegantissima one.

The depositional environment of Puerto La Paloma
N° 449/11 (8.00—7.50 m level, drill sample) pro-
bably was an open sandy beach. This is supported by
the lithofacies, and the fact that the foraminiferal
assiciation is similar to living ones in this biotope
(CLoss & BARBERENA, 1962; MADEIRA-FALCETTA, 1974;
MurRrAY, 1973).

In San Jose de Carrasco N® 442/1 (18—17 m
level, drill cutting) many abraded tests were found
due to the characteristics of the lithofacies which is an
angular quartzose sand. The environment was pro-
bably a sand beach exposed to waves and located on
the estuarine shore. This environment is a difficult
biotope for many anımal groups, because it is mobile
and unstable. The only permanent residents from the
benthic macrofauna belong to the infauna (HEDGPETH,
1957; HERM, 1969; Perkıns 1974; SEILACHER, 1953).
Destruction of foraminiferids and molluscs due to
abrasion is usual in this environment (EınsELE et al.,
1977; MurRAY, 1973).

The distribution of the foraminiferids in Chuy
N? 364 does not agree with the trend that is normal
in estuarine longitudinal zonation. This fact can be
explained in two ways: a) deposition took place in a
marginal marine environment, revealing estuarine la-
titudinal or lateral zonation; b) the foraminiferids
were deposited during a different transgressive event,
being older or younger.

The wells which are located in Colonia and Soriano
Counties, do not contain foraminiferids. "These bore-
holes are located in the innermost estuarine region.
The sequences of these bore-holes, that were consi-
dered as belonging to the Vizcaino Formation, pro-
bably were deposited in a hyposaline environment.
Foraminiferids usually are not adequate for paleoe-
cological reconstruction of these biotopes, because
only few species are able to survive there. This is
also valid for living foraminiferids of the Rio de la
Plata, and is clearly illustrated by REMANE’s curve
of this estuary (fig. 3, d-d’). Post mortal diageneti-
cal effects as i.e post depositional dissolutions, also
could have affected the microfaunas.

It is necessary to evaluate other fossil assemblages to
reconstruct the depositional environments of the se-
quences which are attributed to the Vizcaino Forma-
tion, namely the wells located in Colonia and Soriano
Counties. Mollusca are used for this purposes.

4. PALEOECOLOGICAL INTERPRETATION OF
MOLLUSCAN ASSEMBLAGES.

a. Methods.

The Quaternary malacological associations found in
the wells can be evaluated for paleoecological and
paleogeographical information. On one hand it
allows one to compare and check the paleoecological
conclusions that were given, by foraminiferal assem-
blages. On the other hand they offer a valuable addi-
tional information, particularly for those environ-
ments that are not suitable to foraminiferal life or pre-
servation.

The bivalves and gastropods in the wells are mainly
used to delineate the boundaries between the Quater-

Numbers of species

Salinity

m Marine species

Genuine brackish- water
species

N]
NN Fresh-water species

Fig.5: Graph of numbers of marine, fresh-water, and
genuine brackish-water species in different salinities [after
RemantE (1934, 1940, 1963, 1971)].

nary biofacies and/or environments. They also offer
information that allows one to verify and define the
range of the biofacies during the Querandina Trans-
gression.

For this purpose it was particularly useful to use
criteria that allow a discrimination between marine
and limnic organisms:

1. Marine and limnic environments have been colo-
nized by different species.

2. The curve that establishes a relationship between
the species number and the water salinities was made
by REMAnE (1934, 1940, 1963, 1971) (fig. 5). To-
wards the head of the estuary (inwards the estuary) —
with decreasing salinities — the number of species
decreases. With salinity of 18 %/oo approximately half
of the marine species survive. Limnic organisms are
already very scarce at a salinity of 3 %/oo'. The species
minimum is near the boundary of fresh water environ-
ments, with salinities in the range of 5—8 ®/oo (REMANE,
1934), 5—7 °/oo (REMANE, 1963, 1971), 4—6 °/oo (HıL-
TERMANN, 1963b) or by 5 °/oo (McLusky, 1971; PER-
Kıns, 1974). "The asymmetry on REMANE’s curve origi-
nates by the fact that fresh water species react with
much greater mortality with the increase of water sali-
nities than the marine faunas do with increase of fresh
water. Therefore marine environments are separated
from the limnic ones by a zone characterized by a low
species diversity, with salinities ranging between
5—8 %/oo.

3. Brackish waters are characterized by the presence
of some species which reach their highest abundance in
this environment, and which have been designated
“sgenuine brackish-water species” or “true estuarine
species” (HILTERMANN, 1963b; REMANE, 1934, 1940,
1963, 1971). Generally these species belong to genera
which are present in marine environments, with a few
belonging to limnic environments.

4. An additional useful way is to evaluate the vica-
riad species, i. e. closely related species whose distribu-
tion is allopatric.

b. Curve of REmaANnE for living
bivalves from theRio dela Plata
estuary.

To use the actualistic principle the first step is to
reconstruct REMANE’S curve for the living malaco-
logical assemblages of the intertidal and sublittoral
zones of the Uruguayan part of the estuary. With
this aim a review of the available literature about the
living molluscan faunas at the Uruguayan coasts was
made.

Some limitations of the reconstruction of the curve
that relates the species number to salinities are given:

1. Generally the available information is imprecise
in reference to the species range of dispersion.

2. Usually no discrimination is made between the
information based on living species, and those ob-
tained on the thanatocoenosis.

3. The presence of some species previously refered to
this area must be considered as fortuitous, or are
questionable.

4. The nonexistence in the literature of precise data
about the salinities that existed at the moment in
which the molluscs were capturated.

Notwithstanding these limitations, it was possible to
plot the curve of REMANE for the living bivalves
of intertidal and sublittoral zones of the Uruguayan
coast, within a very acceptable approximation (fig. 6).
For this purpose the number of bivalve species
reported from the following areas were counted:

RECENT BIVALVES

a: .

.
„nt

Numbers of species

SI Ei

Curve of REMANE for living bivalves from the
fresh-water species,

Fig. 6:
Rio de la Plata estuary. Key: I =
II = genuine brackish-water species, III = marine species.
Geographical setting of areas 1—6, as well as references
of column 7 of histogram are shown in pages 40. Lines a,
b and c are the boundaries between estuarine environ-
ments, as shown in Fig. 3.

Uruguayan oceanic region (fig. 6,
area 1): This covers the coasts of Rocha County in
all its extension, and those of County Maldonado,
from Portezuelo to the east. The characteristics of the
living communities of the sandy beaches in this area
were reported by ScAarABINo, MayTiaA & FAEDO
(1973).

The rocky substrates of this region are characterized
by the presence of the Mytilus platensis-Brachidontes
rodriguezi-Perna perna Community (SCARABINO,
Mayria & Caches, 1975).

To establish the number of bivalvian species of this
area, the information provided by the “Catälogo de
los moluscos marinos del Uruguay” was used (Fı-
GUEIRAS & Sıcarnı, 1968b, 1969, 1970a, 1970b), as
well as additional data by BARATTINI & URETA (1960)
and Fıcuriras (1975). A total of 109 species of
pelecypods belonging to the biocoenosis and thana-
tocoenosis were reported. They are tentatively clas-

sified as:

1. marine species, of the intertidial and upper sub-
littoral zones: 83(?)

2. middle and lower sublittoral marine species: 17 (?)
3. genuine brackish-water species: 5

4. not classified and doubtfull species: 4

This data is approximate, because the available in-
formation about the distribution and ecology of many
species is insufficient. Petricola pholadiformis can be
used to illustrate the point. According to FRr£y,
VoorHIEs & Howaron (1975) this species is one of the
best indicators for estuarine environments. Neverthe-
less, in the Rio de la Plata area, its distributional
range is reported as being only along oceanic coasts.

Area of Montevideo (fig. 6, area 2): The
bivalve species living in this zone are described by
SCARABINO, MayTia & Cachts (1975). In the
“sandy beach” physiographic unit, characterized by
sandy substrates with high organic matter the fol-
lowing bivalve species were found: Erodona mac-
troides, Mactra isabelleana and Tagelus plebeins.
These species live in the intertidal and upper sublit-
toral zones. In rocky substrates the Brachidontes
darwinianus Community is dominant, being fre-
quently associated with Mytella charruana. Both
species are also dwellers of the littoral sensu stricto
and upper sublittoral zones. Teısseıre (1927, 1928)
has reported already the presence of these five species
for the coasts of the Montevideo County. FIGUEIRAS
& Sıcarnı (1968b, 1969, 1970a, 1970b) also recorded
along coasts of Counties Montevideo and Canelones
the presence of the same five species, which were des-
cribed as euryhaline forms. They also reported the
presence of Macoma uruguayensis and Mactra petiti
in the same area. Therefore the Area of Montevideo

also includes the coasts of Canelones County, mainly
in its western region.

It must be pointed out, that the Brachidontes dar-
winianus-Mytella charruana Community, which lives
in the area of Montevideo, is substituted in the oceanic
region by another community, integrated by the
vicariad species Mytilus platensis-Brachidontes rodri-
guezi-Perna perna (SCARABINO, MAYTiA & CaAchHEs,
1975). This latter species invaded the Atlantic Uru-
guayan coasts only recently (FIGUEIRAS & SICARDI,
1968b, p. 265).

Goasts of the Colonia County: To
obtain the distributional range of the bivalve species
of this estuarine zone, the information detailed by
OLAZARRI (1966) was used. This autor described the
bivalves of Colonia County. For each analyzed
species a list of the localities in which it was found is
presented. In using REMANE’s curve only those
localities were considered which were located on, or
near the Rio de la Plata, and also those situated on
the Rio Uruguay, between Punta Gorda and Arroyo
Sauce. The localities in the inner part of the County
were excluded, because they could not provide any
information about salinity zonation. The localities in
question were grouped into four zones, along the
coasts of Colonia County:

Mouth of Arroyo Cufr& area (fig. 6,
area 3)

Artilleros area (fig. 6, area 4): localities of
Arroyo Artilleros, Balneario Santa Ana y Puerto
Platero.

Area of Colonia City (fig. 6, area 5):
localities of Playa Ferrando, Bahia de Colonia,
Playa La Arenisca, Barrancas San Pedro e Isla San
Gabriel.

Area of Carmelo and Nueva Palmi-
ra (fig. 6, area 6): localities of Punta Piedras, Playa
Sere, Balneario Zagarzazu, Punta Gorda, Nueva
Palmira and Brisas del Uruguay.

According to OLAzarrı (1966) the total number of
limnic bivalve species found in Colonia County is 24
(fig. 6, column 7). Fıcuziras (1965a, 1965c) presented
a review of freshwater pelecypods of the Uruguayan
territory. He described 29 species. No precise distri-
butional data is offered for many species. The total
number of species is close to that given by OLAZARRI
(1966), especially if it is considered that OLAZARRI
restricted his observations to Colonia County. The
total number of species previously referred to do not
include various subspecies which were reported by
both authors, because in some cases their allopatric
distribution are not evident.

The resultant histogram and curve (fig. 6) reveals a
very similar distribution as in REMANE’s curve
(ig. 5). They also are similar to that REMANE’s

curve which was exclusively plotted for molluscan
faunas (HıLTERMAnN, 1963b; REMAnE, 1934, 1940,
1963, 1971).

For ecological reconstruction, the salinities of each
area previously referred to must be estimated. For
this purposes the zonation of the salinities in the Rio
de la Plata reported by URIEN (1972) is used. This
allows one to establish the relationship existing bet-
ween the inner-fluvial, intermediate-fluvial, fluvio-
marine and marine environments of the estuary, i. e.
areas 1 to 6, of the histogram of Fig. 6. The bounda-
ries between these environments are graphically illu-
strated in the same figure. They also overlap with the
biofacies limits, which were defined using living fora-
miniferids.

The histogram and curve of Fig. 6 indicate the fol-
lowing conclusion:

Inthe oceanic region the species diversity is
very high (area 1). According to REMANE’s curve
it must have a relationship with euhaline and poly-
haline salinities.

In the inner-fluvial environment,
where limnic conditions are always present, the fauna
of fresh water bivalves is also diversified (areas 5 and
6).

Inthe intermediate-fluvialenviron-
ment the increasing salinities causes a quick decrease
of the number of limnic bivalve species. In the Arti-
lleros area eight fresh water species were reported
(area 4), and in the mouth of Arroyo Cufre only two
(area 3). These limnic bivalves coexist with Erodona
mactroides. REMANE (1963) and HıLTErMmann (1963b)
reported that the dominant fauna in oligohaline
waters is a limnic one, but with an evident decrease in
species diversity. The lowest diversity is reached in
the miomesohaline (= ß mesohaline). According to
REMANE (1971) fresh-water bivalves are rather intole-
rant of brackish water. Only a few reach the 5 %/o0
boundary, none transgress the 8 %/oo salinity limit.
Based on these data it can be concluded that the
bivalves of the Astilleros area indicates an approxi-
mate oligohaline environment; and those of the
Arroyo Cufre shows a miomesohaline one.

In the fluvio-marine environment
only seven bivalve species were reported of marine
origin. This faunal spectrum indicates mesohaline
salinities.

An examination of the range of distribution of the
genuine brackish-water species shows clearly that their
optimum lies in the mesohaline. The salinity ranges
from about 3 %/o0 to 18%/vo and is the habitat of over
90°%/ of the genuine brackish-water
(REMANE, 1971).

The genuine brackish-water species are here defined
according to REMANE’s (1934) wider definition:

organisms

“Genuine brackish-water species are those which
abound in brackish water and occur only occasionally
in the sea or fresh water”. Often great practical
difficulties exist in establishing if a species belongs to
this category, or if it is a euryhaline form. A classical
example is the case of Mytilus.

Erodona mactroides, Brachidontes darwinianus,
Mytella charruana and Tagelus plebeius are considered
to be genuine brackish-water species. SCARABINO,
MayTia & Caches (1975) included these species
within the “estuarine association”.

Probably Mactra isabelleana must also be consi-
dered a genuine brackish-water species. This species
is dominant in several exposures of the Querandinense
which are characterized by very low saline depositio-
nal environments. CALCATERRA (1971) reported that
Mactra isabelleana constitutes about the 60/0 of the
fossil assemblage in Cantera Ferrando. This species
is also dominant in Punta Francesa constituting 400/o
of the molluscan fauna, and in the ex cementerio de
Nueva Palmira, where its occurence goes to 90/n.
Borpas (1957) also considered Mactra isabelleana as
being an “estuarine species”. KLAPPENBACH &
SCARABINO (1969, p. 54) reported that this species
prefers waters of low salinity. It must be pointed out
that Teısseıre (1927, 1928) was the first who
recognized the palevecological value of these five
genuine brackish-water species.

Macoma uruguayensis and Mactra petiti are consi-
dered as euryhaline marine species. Their range of
distribution goes from Montevideo toward the east,
but they do not constitute dominant forms in this
environment.

Among these five genuine brackish-water species
there is one, Erodona mactroides, that has been
repeatedly mentioned as being useful for ecological
and paleoecological interpretations (CARCELLES, 1941;
Cross, 1963; Costa, 1971; FIGUEIRAS, 1965a; OLA-
ZARRI, 1966; TEISSEIRE, 1927, 1928).

Cross (1963) offers precise information about the
distributional pattern of Erodona mactroides, and its
direct correlation with water salinities. In Laguna de
los Patos this species is scarce in areas with relatively
high salinities (polyhaline), and is completely absent
in fresh water zones. It is frequent in salinities
ranging between 15—8/oo, and can be very abundant
in waters whose salinities fluctuate between 9—3 %oo.

In reference to the westernmost penetration of Ero-
dona mactroides in the Rio de la Plata, the most
accurate information is given by TEıssEıre (1927) and
OLAZARRI (1966). The former author indicated that
this species was found near Colonia City. OLAZARRI
(1966) described the presence of some big specimens in
the harbour of Colonia City, together with nayades,
emphasizing that Erodona mactroides never was

found living at the NW of this geographical area, on
the Uruguayan coast.

These biological data are in total agreement with
the physical parameters of water salinities, which were
described by URıEn (1972). The limnic sensu stricto
environment begins somewhat to the NW of Colonia
City, on the Uruguayan coast. There Erodona mac-
troides disappears in living assemblages. That means
that the maximum headward estuari-
ne penetration of Erodona mactroides in-
dicates the nearness of the boundary
between the inner-fluvialand inter-
mediate-fluvialenvironments.

The remaining genuine brackish-water species were
not found living on the Colonia County coasts
(OLAZARRI, 1966), not even in San Jose County. To-
wards the head of the estuary the maximum penetra-
tion was observed along the coasts of the area of
Montevideo (fig. 6, area 2), as was described by
FiGUEIRAS & SıcarDı (1968b, 1969, 1970a, 1970b) and
TeısseireE (1927, 1928).

Life habits of the dominant genuine
brackish-water species.

The life habits of Tagelus plebeius were extensively
described by Stantey (1970) as being a suspension-
feeder of the deep infauna.

No detailed biological studies have been made of
Erodona mactroides and Mactra isabelleana life
habits. However they have been tentatively estab-
lished using criteria formulated by Cox, NuTTAaıL &
TRUEMAN (1969), KAuUFFMAN (1969) and STANLEY
(1970).

Erodona mactroides is considered to be a suspen-
sion-feeder of the upper infauna, based on the functio-
nal morphology of its test, i. e., absence of a pallial
sinus and its taxonomic position within the Myacea.

Mactra isabelleana is a suspension-feeder of the
intermediate infauna.

Apparently no genuine brackish-water bivalve
detritus feeders exist in the Rio de la Plata. In
almost all estuaries the detritus-feeders are present as
characteristic forms. Suspension-feeding bivalves are,
however, generally rare in estuaries (BARNEs, 1974).

ec. Distribution of the living gastro-
podsintheRio de la Plata estuary,
anditszoneofinfluence.

The distributional pattern of the gastropod species
is as follows (fig. 7):

In the oceanic Uruguayan region the
presence of about 183 species of gastropods from the
biocoenosis and/or thanatocoenosis were reported
(FIGUEIRAS & Sıcarnpı, 1970c, 1971, 1972, 1973, 1974;

RECENT GASTROPODS

s3a19ads Jo sıoaquwinn

Fig. 7: Distribution of living gastropods in the Rio de la
Plata estuary, and its zone of influence. Key: I = fresh-
water gastropods, II = genuine brackish-water and/or
euryhaline limnic species, III = genuine brackish-water spe-
cies, IV = marine intertidal and upper sublittoral species,
V = middle and lower sublittoral marine species, and pe-
lagic forms. Location of areas 1—4 and their features are
given in pages 42,43. Lines a,b and c are the boundaries be-
tween estuarine environments, as shown in Fig. 3.

Sıcarpı, 1975). The taxonomic status and/or the
ecology of many of these species are little or not at all
known. These species were tentatively, and in an

approximate form, grouped as:

1. marine species which are typically from the middle
and lower sublittoral zones; and pelagic forms: 58(?)
(fig. 7, area 1). They live together with many species
of the next area.

2. marine intertidal and upper sublittoral species:
102 (?) (fig. 7, area 2)

3. genuine brackish-water and euryhaline species: 2.

4. unclassified and doubtful species: 21.

According to FıGuziras (1964) and FIGUEIRAS &
Sıcarpı (1971, 1972, 1974) the following species were
recorded from the littoral sensu lato of Monte-
video County (fig. 7, area 3): Littoridina
australis, Littoridina charruana, Littoridina isabellea-
na, Parodizia uruguayensis, Buccinanops deformis,
Cylichna (Cylichnella) bidentata, Caecum capitanum

and Meioceras tumidissimum. The presence of the last
two species in this region must still be confirmed
(KLAPPENBACH, 1964). Buccinanops deformis is a
marine stenohaline species (FIGUEIRAS & SICARDI,
1968a, p. 237). Cylichna (Cylichnella) bidentata is
not abundant.

Littoridina australis is the unique dominant gastro-
pod in this region, and is considered as an “estuarine
species” by Borpas (1957), OLIVER et al. (1972) and
SCARABINO, MAyTia & CacHts (1975). According
to the latter authors, this genuine brackish-water
species is found on sandy substrates with high a con-
tent of organic matter, in the intertidal and upper
sublittoral zones; and also in the “marshland” i. e.
in muddy sediments.

No precise data were published about the tolerance
of Littoridina australis in relation to decreasing water
salinities. PArovız (1962) indicates that its habitat is
always “brackish”. BaraTTını & URETA (1960)
considered that it is a typical species in “brackish”
and “limnic” environments. This point of view is
also supported by Fıcuzıras (1964), who writes that
the normal biotope of Littoridina australis lies ın
“brackish waters”. CamacHo (1966) considered
this species as an euryhaline form. CAsTELLANOs (1965)
has described Littoridina australis in Punta Lara
(Buenos Aires County), as being very abundant and
coexisting with numerous limnic species. Punta Lara
is located in the region were the boundary between
the inner-fluvialand intermediate-fluvial environments
is found.

Littoridina charruana, Littoridina isabelleana, and
Parodizia uruguayensis were also reported from the
coasts of the Montevideo County (BARATTINI &
URETA, 1960; FIGUEIRAS, 1964; PEREIRA DE MEDINA,
1959). The available information about these spe-
cies is mainly based on the thanatocoenosis. The lack
of ecological data of the biocoenosis makes it difficult
to decide if they are genuine brackish-water species or
euryhaline limnic ones.

Besides, it must be remembered that a more marked
tolerance of changes in salinity is found in the limnic
gastropods than in bivalves (REMANE, 1971).

Along the coasts of Colonia County (fig. 7,
area 4) the existence of 17 to 19 stenohaline fresh-
water gastropod species were reported (FIGUEIRAS,
1964, 1965c). This number must be considered as an
approximation due limitations previously cited.
Moreover, Littoridina australis, Littoridina charruana,
Littoridina isabelleana and Parodizia uruguayensis
are also present.

The distributional pattern of gastropod species from
the intertidal and upper sublittoral zones of the Uru-
guayan estuarine and oceanic regions, shows an
evident similarity with those of the bivalve fauna:

1.intheoceanic region a high species diver-
sity is present, indicating an euhaline and polyphaline
environment.

2.the fluvio-marine environment is
characterized by a low species diversity. The genuine
brackish-water species Littoridina australis is here do-
minant. Besides, in this environment were found
limnic euryhaline and marine species.

3.in the inner-fluvial environment
high species diversity is present.

4.no precise data areavailable for the interme-
diate-fluvial environment, which could
be fitted graphically into REMANE’s curve. It can be
inferred that the species diversity decreases, if the
highs of columns 3 and 4 on the histogram in Fig. 7
are interpolated.

Some facts about the distribution of the living mol-
luscs in the Rio de la Plata region must be given.
The salinity is the main environmental factor which
determines the distribution of the bivalves and gastro-
pods. This result is the same as that given for the
molluscan faunas in different estuaries (Davıss, 1972;
DörjJEs & Howarp, 1975; HEDGPETH, 1957; HILTER-
MANN, 1963b; McLusky, 1971; REMANE, 1934, 1940,
1963, 1971). Therefore they are valid correlations,
between the molluscan assemblages and environments,
based fundamentaly on the salinity tolerance of the
bivalve and gastropod species. Nevertheless, it must
be remembered that the distributional pattern of the
molluscan faunas is also subjected to other environ-
mental factors, as temperatures, type of sediment, cur-
rents and tides, bathymetry, water turbidity, food
availability, oxygen concentration, ionic concentra-
tion, flocculation of silt particles, etc. (Davies, 1972;
Dörjes & Howarnp, 1975; EMERY & STEVENSON,
1957; GREEN, 1968; HEDGPETH, 1957; McLusky,
1971; PARKER, 1955, 1959, 1975). In an estuarine
environment a faunal dislocation, like te one illustra-
ted by EmErY & STEvEnson (1957, fig. 2) can also
occur, as well as sediment and faunal mixings.

The fine sediments deposited in the estuarine en-
vironment display another particularly important
feature. Their interstitial water is more constant in
its salinity than the overlying water body. Although
the interstitial salinity reflects the salinity of the
overlying water, changes in the interstitial salinity
take place at a much slower rate. Many species
utilize this ameliorating effect of the substrate to
survive in this unstable environment (Barnes, 1974;
McLusky, 1971). This ameliorating effect also fa-
vours the paleoecological reconstruction because it has
a stabilizing result on the biocoenosis, and therefore
on the thanatocoenosis.

In short, the present day distributional pattern of
the molluscs in the Rio de la Plata estuary show very
evident trends, which will be used for the paleoecolo-
gical and paleogeographical interpretation.

d. Reconstruction of Quaternary
depositionalenvironments

The molluscan faunas deposited in Uruguay during
the Querandina Transgression have been referred to in
many publications. The most important are those of
Bornas (1957), Broccı (1967, 1970, 1973), CALcA-
TERRA (1971), DE MATA (1947), FiGUEIRAS (1961, 1962,
1967, 1973), Francıs (1975), FRENGUELLI (1930),
GoNı & HorrsTETTER (1964), IHErING (1907, 1923,

QUATERNARY

ELLE

SZEL

202

DER
SOLLE

27
L3
46

B A

100%

[=] Numbers of species

% genuine brackish-water
and euryhaline species

Fig. 8a: Distribution of Quaternary molluscs found in
bore-holes and Lecocq. The bore-holes are grouped in
areas A to D, as is explained in pages 45. Fig. 8b: Shows
the percentile occurence of genuine brackish-water and
euryhaline species in each area. Key: b = gastropods, c =
bivalves, d = polyplacophorids.

1930), KrAGLiEvIicH (1928, 1932), PaARoDız (1962) and
TeısseirE (1927, 1928). Recently Cross & Forri
(1971) and Forrı (1969) described molluscan faunas
of the same age from southern Brazil. The largest
part of this research concerns itself with taxonomy
and stratigraphy, whereas the paleoecological and
paleogeographical interpretation were somewhat
downgraded. The work of TeıssEire (1928) was the
exception in which the paleovecological data is still
of great use today.

MOLLUSCS

W200002

X 7

Numbers of species

wa u ne rn

DS
BD

POLY.-EU.

% genuine brackish-water o|
and euryhaline species

54 3 2 4

Fig. 9a: Distribution of molluscs recorded at exporsures
of Vizcaino Formation. These outcrops are located in
areas 1to5. Their geographic location are given in page 45.
Fig. 9b: Percentile occurence of genuine brackish-water
and euryhaline species. Key: a = Chilina sp.?, b = gastro-
pods, c = bivalves, d = polyplacophorids.

To establish the tolerance of certain species of water
salinity, the work of Frey, VooRHIES & HowArD
(1975), PARKER (1955, 1956, 1959, 1975) and STANLEY
(1970) were also taken into consideration.

The study of Quaternary malacological assemblages
begins with faunas recorded from wells
and in Parque Lecocg. The histogram of
Fig. 8a is designed to study the distribution of Qua-
ternary molluscs, and their relationship to REMANE’s
curve. Only those assemblages which allow one to
identify the “estuarine front” of the transgression
were used. The malacological faunas which were
deposited in the “lateral-marginal zone of influence”
were excluded. The bivalve and gastropod associa-
tions are grouped as follows:

Area A: species found in Costa Azul N° 1060/1,
La Paloma N° 482/1 and La Paloma N° 449/11.

Area B: San Jose de Carrasco N° 442/1 and
Parque Lecocgq.

AreaC :Carmelo N° 235 and Carmelo N? 245/1.

Area D: Bore-holes Rio Uruguay N° 445/1
and Soriano N? 483/2.

The distribution of the bivalve and gastropod spe-
cies is similar to those illustrated in the right half of
REMANE’s curve.

The species spectrum of area A is similar to that
reported for living assemblages of the oceanic region
of Uruguay. Brachidontes rodrignezi and Mytilus
platensis are also present. Both species make up a
living community, which was defined for the living
malacological faunas of the oceanic region of Uru-
guay. The area A assemblage indicate the prevalence
of marine conditions.

In area B the species diversity decreases. In
San Jose de Carrasco N° 442/1 the faunal spec-
trum indicates a polyhaline environment. In Lecocq
it suggests a greater fall of water salinity, which was
partially determinated by Rio Santa Lucia runoff.

The diversity and faunal spectrum in area C
corresponds predominately to a miomesohaline (= ß
mesohaline) environment, with a certain influence of
pliomesohaline (= a mesohaline) waters. According
to REMANE (1963) and HiLTERMANN (1963b) the plio-
mesohaline is characterized by the dominance of a
marine fauna, represented by few species. They
coexist with genuine brackish-water species, and with
some very tolerant limnic euryhaline ones. The mio-
mesohaline is the most optimum environment for the
genuine brackish-water species development, scarce
euryhaline and limnic forms also being present. The
associations in area D indicate miomesohaline sali-
nities.

The Brachidontes darwinianus Community is pre-
sent from Lecocgq towards the inner part of estuary.

This species is also recorded at Carmelo N° 245/1
and at Rio Uruguay N° 445/1. Today this com-
munity lives in the fluvio-marine environment.

The percentile occurence of genuine brackhish-water
and euryhaline species in areas A-D is illustrated
in Fig. 8b. It is minimal at area A. At San Jose de
Carrasco N° 442/1 it reaches 11°/o for bivalves.
From Lecocq towards the estuarine head or to the
NW, it is evident that there is an increase in the per-
centile occurence of these species, which are excellent
indicators for reduction in water salinity.

The given data are almost exclusively based on the
malacological assemblages found in the wells. This
fact may imply some limitations:

1. the number of specimens recorded from each drill
cutting is low, and could introduce a bias in reference
to species diversity,

2. the localities in which the wells are situated, are
not always the most appropriate in analyzing faunas of
the Querandina Transgression. The study of the mol-
luscan assemblages recorded from wells also can bring
adventages, because the drill samples generally con-
tain those species which are dominant in their associa-
tions.

To verify the authenticity and validity of any given
conclusions, a review of the available literature about
molluscan faunas recorded from the
Vizcaino Formation exposures will be
made. The re-examination of these faunas is offered,
in an attept to adjust the information in reference to
species diversity, and obtain additional data that are
not available through the wells.

A faunal study made with this method presents
several handicaps. The most relevant one is the multi-
plicity of criteria and methods used in faunal descrip-
tions by different researchers. All the consulted work
was not written with an aim towards paleoecological
results. It is not possible in many situations to decide
if the assemblages are autochthonous or allochthonous.
Besides, faunas collected in different facies are related.

A histogram is given that indicates species diversity,
in the following areas (fig. 9a):

Montevideo and Areneras de Carrasco (area 1).

Colonia City (area 2).

Carmelo and Nueva Palmira (area 3).

Soriano (area 4).

Fray Bentos and Mercedes (area 5).

The geographic extension of these areas, the impli-
cated exposures, and the bivalve and gastropod spe-
cies that they contain, are contained in SPRECHMANN
(1978b).

The resulting histogram (fig. 9a) possess a similar
configuration with the one prepared for the malacolo-
gical faunas recorded from the wells (fig. 8a).

The following conclusions are established on the
molluscan assemblages recorded from the Vizcaino
Formation exposures:

The area 1 (Montevideo and Areneras Carrasco)
is characterized by:

1. a high species diversity (fig. 9a),

2.the per cent occurence of the genuine brackish-
water species is small (fig. 9b); and

3. these associations possess predominantely a marine
species spectrum, indicating an euhaline-polyhaline
environment.

Area 2shows:
1. an evident decrease of the diversity (fig. 9a);

2.the per cent occurence of the euryhaline and ge-
nuine brackish-water species increases greatly;

3. these associations possess predominantelya marine
species coexist. This association is attributed to a
pliomesohaline environment.

The assemblage of area 3 is also included within
the mesohaline environment, but having lower salinity
than area 2.

Inarea 4a definite difference between the bivalve
and gastropod diversity is present. The former are
represented by eight species, whereas the latter only
possess two. The diversity, faunal spectrum and per
cent occurence of the genuine brackish and euryhaline
bivalve species, indicate pliomesohaline salinities
(fig. Ja—b). In contrast the gastropods reveal a mio-
mesohaline environment. They are only represented
by Littoridina australis, a genuine brackish-water
species, and Chilina sp.?, probably a fresh water snail.

For area 5 only Erodona mactroides was
reported, but the faunal content of the exposures in
this region are little known as yet. They are con-
sidered as belonging to the miomesohaline environ-
ment.

The Archaeogastropoda (excluding the Neritacea)
are the most intolerant gastropods as far as brackish
environments is concerned (REMANE, 1963). In
area 1, which is considered a euhaline-polyhaline
environment, five Archaeogastropod species were
reported, whereas in the remaining areas, only one
was found.

These results, carried out on the molluscan faunas
from different exposures could be affected by some
built in errors. The weakest aspect is the overevalua-
tion of the incidence and value of uncommon and rare
species. In the case of the histogram in Fig. 9a this
risk is grater, because the majority of the authors that
have described the molluscan faunas of the Vizcaino
Formation put a special emphasis on the description of
rare species. They gave special importance to repor-
ting even greater numbers of molluscan species in each

different exposure. This could even be enlarged by
taxonomic and nomenclatural disagreements.

To counteract this as much as possible, the percentile
occurence of genuine brackish-water species must be
evaluated. These data are not obtainable from
assemblages in drill cuttings. Data as to percentile
occurence of the recorded species in each fossiliferous
locality are not found in the literature. The unique
exception is a paper of CALCATERRA (1971). This
worker studied several exposures of the Vizcaino For-
mation which are located in Colonia and Soriano
Counties. For each outcrop the percentile occurence
of found specimens belonging to each species is pre-
sented. Only those species that constitute more than
1°/o of the assemblages in each outcrop were con-
sidered. Fig. 10 was plotted by using CALCATERRA’S
data. There the per cent occurence of genuine
brackish-water species in the following exposures is
offered: Cantera Ferrando (area i), Bahia de Colonia
(area 11), Arroyo San Pedro (area iii), Punta Francesa
(area iv), ex-cementerio de Nueva Palmira (area v),
Colonia Concordia (in Rincön del Catalän) (area vi),
and Pueblo Soriano (area vii). From an analysıs of
fig. 10, the fact stands out that the genuine brackish-
water species constitute more than 900/o of the assem-
blages located between Bahia de Colonia and Pueblo
Soriano. They make up the trophic nucleus of their
assemblages. Somewhat to the east, in Cantera Fe-
rrando, they constitute 65 %/o of the assemblages. This
evidence shows the value of genuine brackish-water
species, and this fact must be taken into consideration
for paleoecological and paleozoogeographical recon-
structions.

Fig. 11 is designed with this aim in mind, based also
on data of CALCATERRA (1971). For each locality the
percentile occurence is illustrated by the following:

1. marine species,

2. the recorded genuine brackish-water species: Tage-
lus plebeius, Mactra isabelleana and Erodona mactroi-
des,

3. limnic species.

The assemblages plotted in Fig. 11 can be grouped
as follows:

Brackish assemblage, with a moderate
marine influence: locality ıi.

Brackish “polyspecific” assembla-
ges. They have three dominant genuine brackish-
water species: localities ii and iv.

Brackish “*monospecific”
blages. A single genuine brackish-water species is
dominant: localities iii, v, viand vıı.

assem-

One of the greatest difficulties for paleoecological
reconstruction of an estuarine region, is to discriminate
between the “estuarine front” and the “lateral-mar-
ginal zone of influence”.

QUATERNARY MOLLUSCS

% genuine brackish-
water species

Fig. 10: Percentile occurence of genuine brackish-water
species from several exposures from the Vizcaino Formation
in Colonia and Soriano Counties (after CALCATERRA, 1971).
Exposure location is indicated on page 46.

On Fig. 11 criteria for the identification of the
associations deposited in the “estuarine front” are
given. It allows to select the representative assem-
blages for reconstruction of saline zonation during the
Querandina Transgression.

The assemblages ii and iv are comparable with the
living ones on the shores of Montevideo County.
Hence, they belong to the fluvio-marine environment,
and indicate mesohaline salinity. According to
SCARABINO, MAYTiaA & Cachts (1975) their faunal
spectrum is typical for sandy muddy sediments. The
absence of Brachidontes darwinianus mulleri and/or of
Mytella charruana is a consequence of the absence of
hard grounds in this area.

The brackish “monospecific”
semblages are considered as indicative of inter-
mediate-fluvial environments (oligohaline-mesohaline).
Only two brackish “monospecific”assemblages iden-
tify the “estuarine front”: the associations found in
the exposures of the ex-cementerio de Nueva Palmira
(fig. 11, area v), and in Pueblo Soriano (fig. 11, area
vi). On the contrary, the fauna recorded from loca-
lities iıı and vi were deposited in the “lateral-mar-
ginal zone of influence”.

as-

Detailed evidences allows one to establish, with
reasonable certainty the geographical setting of the
Transitional-area between fluvio-
and intermediate-fluvial
environments during the Querandina Trans-
gression. It was located approximately between
Punta Francesa and Nuava Palmira. The term
“Transitional-area” is used to underscore
the fact that the changes between the environments
are gradual. The faunal association of a “Transitio-
nal-area” is constituted by a combination of those
species from adjacent environments.

marine

The analysis of depositional environments provided
by malacological assemblages of bore-holes Carmelo
N° 245/1 and Carmelo N° 235 (fig. 13) permits
one to define even more closely the location of the
Transitional-area between fluvio-marine and inter-

100%

QUATERNARY MOLLUSCS

at] Marine species

IM Genuine brackish-water species
c d
iin. sp?
e

Fig.11: Faunal composition in the various exposures from
the Vizcaino Formation in Colonia and Soriano Counties
(after CALCATERRA, 1971). Key: a = marine species,
b = Tagelus plebeins, c = Mactra isabelleana, d = Ero-
dona mactroides, e = Chilina sp.?. Location of exposures
i — vilisshown on page 46.

mediate-fluvial environments. It allows one to deduce
that it was situated between Carmelo and Nueva
Palmira (fig. 12).

During the Querandina Transgression, the Tran-
sitional-area between intermediate-
fluvial and inner-fluvial environ-
ments was located somewhat to the north of Fray
Bentos, and a little east from Mercedes (fig. 12).

Identification of euryhaline bi-
valveand gastropod species

Several molluscan species found in the Rio de la
Plata estuary were defined as genuine brackish-water
species and marine euryhaline ones by the mala-
cologists that studied the living faunas of the region
(Chapter VI. F. 4. b—c). The analysis of the range of
distribution from the species found in the Querandina
Transgression allows one to infer that the following
species must be considered as marine euryhaline forms:
Anomalocardia brasiliana, Ostrea equestris, Pitar
rostratum, Acmaea subrugosa, Thais (S.) haemastoma

and Siphonaria (P.) lessoni.

ENVIRONMENTS OF THE

27 zZ

ST.

BUSCHENTAL

GR 3. ARROYO
72 = SAUCE > ARROYO
G & £ PANDO

Fig. 12:
lities of the Querandina Transgression. The following environments were identified: 1 = inner-
fluvial environment, 2 = Transitional-area between intermediate-fluvial and inner-fluvial en-
vironments, 3 = intermediate-fluvial environment, 4 = Transitional-area between fluvio-marine
and intermediate-fluvial environments, 5 = fluvio-marine environment, 6 = Transitional area

between marine and fluvio-marine environments, 7 = marine environment.

information about indicated localities.

QUERANDINA TRANSGRESSION

e) Paleoecological reconstruction on
molluscs from additional localities
ofthe Querandina Transgression.

The depositional environments of the strata of
various outcrops which were assigned to the Queran-
dina Transgression, are established on the basis of
their molluscan assemblages. For this purpose a
method of analysis is used, which defines following
parameters:

1.the faunal spectrum,

2. the number of present stenohaline-marine, euryha-
line-marine, genuine brackish-water, euryhaline-lim-
nic and stenohaline-limnic species, and their per cent
occurence.

3. determination of the number of dominant species
in each assemblage.

These data are compared with ones used for living
assemblages, and also for those plotted on Figs. 8, 9,
10 and 11.

This method is applied on the molluscan assem-
blages described by the named authors in localities
from:

ARROZAL 33

=
DEN Mi

VUELTA
DE LOS
NARANJOS

annovo/) EN

CHUY

VALIZAS

ARROvO[ ||) Ei
ESS,

Numerical decrease: Salinity decrease

Paleoecological reconstruction of estuarine environments as well as on additional loca-

See pages 49 for

Rio Grande do Sul (southernmost Brazil):
malacological associations from exposures E,, Es,
E,, E, and E,, located in the Santa Vitöria do Palmar
County (Cross & Forrı, 1971).

Uruguay: Arrozal 33 (SErRA, 1944), Vuelta de
los Naranjos, section II (SERRA, 1944), Arroyo Chuy
(FiGuEirAs, 1967), Arroyo Valizas (Broccı, 1970),
Arroyo Pando (Broccı, 1967), Buschental (KRAGLIE-
vıcH, 1932), Arroyo Sauce-Boca de los Ceibos (Teıs-
SEIRE, 1928).

Using the proposed criteria corresponding environ-
ments were established, as is illustrated in Fig. 12.
These environments are related with the shown
estuarine zonation during the Querandina Transgres-
sion. It must be remembered that the reconstruction
was approximate in determined environments. The
degree of correctness in this approach depends on the
realiability and accuracy with which faunal records
were made in each fossiliferous locality.

The depositional environments show the following
relationships with the estuarine ecozones (fig 12):

CARMELO N? 235

HR. SORIANO

$_ RIO URUGUAY
CARMELO N? 245 /1

[I RINCON DE LA BOLSA
4 SAN JOSE DE CARRASCO

1. The assemblages from the exposures E,, E,, Ar-
royo Valizas, Arroyo Pando and Sauce-Boca de los
Ceibos belong to the marine and “estuarine front”
depending on their geographic setting.

2. The molluscs of localities Arroyo Chuy, E,, Es, E,,
Arrozal 33 and Vuelta de los Naranjos were deposited
in the “lateral-marginal zone of influence”.

3. During the Querandina Transgression the Laguna
Merin was inhabited (settled), in the Arrozal 33
region, by a molluscan fauna which is characteristic
for the fluvio-marine environment. In contrast, today
in the inner part of the Laguna Merin the salinities do
not exceed values of 0.2/oo, reaching exceptionally up
to 1°/oo (CLoss & MEDEIROS, 1967; MADEIRA-FALCET-
TA, 1974).

4. Throughout the course of the lower Holocene
Transgression, the Laguna Merin was directly open
to the ocean in its southernmost part. 'The molluscan
assemblages from Santa Vitöria do Palmar County
and Laguna Merin display a zonation beginning with
marine environments that range to fluvio-marine, and

DEPOSITIONAL ENVIRONMENTS AND
ECOSTRATIGRAPHIC CORRELATIONS
OF BORE-HOLES AND LECOCA

n
=
> r

o nn

< ri &
S 3 5
“ =; =
z r z
= < a
° = 29

2 3 30

5 4

E s

o 3

"3 A

SALINAS
oeno
1} PirIaroLıs

Fig. 13: Depositional environments of bore-holes and Lecocg, and ecostratigraphic correlations.

Key: a =

= intermediate-fluvial environment, b = Transitional-area between fluvio-marine and

intermediate-fluvial environments, c = fluvio-marine environment, d = Transitional-area be-

tween marine and fluvio-marine environments, e

= marine environment. — 1 = environment

not identified, material lacking, 2 = environment tentatively established.

somewhat to the north into those of the intermediate-
fluvial environment (fig. 12). It is not the purpose of
this paper to make a detailed reconstruction of the
facies and paleogeography of the Laguna Merin
during the Querandina Transgression, or to determine
its relation with the coastal plain evolution. JosT,
SoLIanı Jr. & GopoLrHIn (1975) studied the paleogeo-
graphical evolution of this region during the Quater-
nary. They described the existence during the Flan-
drian Transgression of an inlet between the sea and
Laguna Merin, located in the proximity of the loca-
lity of Taim, which was designated as “Vertedouro
do Taim”. However, they did not mention the pre-
sence of any Holocene connexion between Laguna
Merin and the ocean, which was situated to the south
of “Vertedouro do Taim”.

5. DEPOSITIONAL ENVIRONMENTS
DETERMINED BY WELL DRILLING AND IN
PARQUE LECOCQ

The ancient environment of each Quaternary fossi-
liferous drill cutting from bore-holes, and from Le-
cocq, is represented on the basis of the evaluation of
foraminiferal and molluscan associations (fig. 13).
The conclusions which were established on those drill
cuttings carrying scarce fossiliferous material must be
considered as approximate.

G. Biostratigraphy

The paleoecological and paleogeographical recon-
structions previously presented have several different
biostratigraphic consequences:

1. ECOSTRATIGRAPHIC CORRELATIONS

It is not possible to make time-biostratigraphic cor-
relations using index fossils.. This is the usual situa-
tion working with Quaternary benthic assemblages.
Besides, there are no climatic fluctuations of great
enough extent to be used for time-stratigraphic corre-
lations.

The only way to establish biostratigraphic correla-
tion is by using ecostratigraphic units or ecozones.
These ecozones are correlated by their place in the
cycle of greatest salinity. A similar technique was
used by Israzıskı (1949) and KRUMBEIN & Sross
(1963, fig. 10—18), who made their correlations using
the method of position in the bathymertric cycle.

The ecostratigraphic correlations that are proposed
are illustrated on Fig. 13. The presented time-strati-
graphic horizon contain fossil associations carrying
different faunal spectra. For these correlations only
those assemblages are taken into consideration which
were deposited in the “estuarine front”. Only the

assemblages that indicate environments with the
greatest salinity for each estuarine region are used.
This stratigraphic position then may be considered to
be time equivalent at each well.

The fossil associations of San Luis N° 1072/1,
Chuy N° 364 and Piriapolis N° 431/7 show environ-
ments that are not in agreement with the cycle of the
greatest salinity for their geographical setting. They
could have been deposited in:

a) the “lateral-marginal zone of influence” being in
this case isochronous.

b) the course of an earlier or latter transgressive
event. For Chuy N° 364 it is shown that the fossil
assemblages were more ancient, being deposited during
the Pleistocene (Chapter VII).

The reliability of the provided correlations increa-
ses towards the head of the estuary. From Salinas to
the NW net differences between the contemporaneous
depositional environments are present, as a consequen-
ce of displacements of depositional environments
during the Querandina Transgression.. On the con-
trary, the depositional environments found in Costa
Azul N° 1060/1, La Paloma N° 482/1, and La Palo-
ma N° 449/11 correspond to a marine environment,
being coincident with the ones existing today in these
localities. Hence, a correlation supported on the
environmental displacement is not possible, due to the
absence of differentiated depositional environments.
The indicated correlation between these wells must be
considered as tentative.

The ecostratigraphic correlations illustrated in
Fig. 13 must be confirmed and verified by C 14 dating.

The above is dealt more extensively by SPRECH-
MANN (1978a).

2. DATA SHOWING THAT THE ASSEMBLAGE
ZONES DESCRIBED FOR THE URUGUAYAN
QUATERNARY ARE INVALID

The age of malacological associations found in the
region of Nueva Palmira and southern Fray Bentos
have given origin to some controversy. The prevai-
ling opinion has assigned them to the Querandinense,
but some workers included them within the Belgran-
ense (CASTELLANOS, 1948; Francıs, 1975; FRENGUELLI,
1930; GoNı & HOoFrFSTETTER, 1964; KRAGLIEVICH,
1928, 1932). A paleontological argument was used
supported on the presence or absence of certain species,
which were considered typical for each stage. Mactra
isabelleana and Thais haemastoma were mentioned as
characteristic fossils for the identification of the Bel-
The faunal assemblages deposited during
the Querandinense may be recognized by the domi-
nance of Erodona mactroides. Nevertheless, ForTI
(1969) correctly considered that Mactra isabelleana
isa typical form in the Querandinense.

granense.

The time-stratigraphic interpretation supported on
the presence or absence of these species are incorrect.
They are isochronous. Their presence or absence in a
certain time equivalent assemblage is due to environ-
mental factors, one being the salinity. Moreover, the
benthic molluscs have a patchy distributional pattern
(PARKER, 1975).

Francıs (1975) defined the following biostratigra-
phie units:

a. Thais haemastoma Assemblage Zone
(middle Pleistocene?), which is tentatively correlated
with the Belgranense;

b. Erodona mactroides Assemblage Zone
(Vizcaino Formation: upper Pleistocene-Holocene);

c. Elphidium discoidale Assemblage Zone
(Chuy Formation and Vizcaino Formation: upper
Pleistocene-Holocene); and

d. Littoridina australis Assemblage Zone
(La Plata Formation?: Holocene).

The results proposed by Francıs are the consequence
of a mistake. As is indicated in the present work,
the species that identify the assemblage zones are
essentially time-parallel. Therefore they can not be
used as time-stratigraphic indicators, because their
presence or absence in an association is determined by
facial and ecological changes.

H. Results of the Holocene
paleogeography in the Rio de la Plata
region

The available data of the history of the Rio de la
Plata supported on C 14 datings (Chapter VI-E), and
the proposed ecostratigraphic correlations (Chapter
VI-G-1), allow one to conclude that the major part of
the foraminiferal and molluscan assemblages were
deposited during the first transgresive phase of the
Holocene Transgression.

According to URIEN & OTTMANN (1971) during the
early Holocene the waters transgressed penetrating
deep into the estuary. Sea level reached as far as
+ 8 m above present stand.

The paleoecological reconstruction corroborated the
existence of displacement of the estuarine depositional
environments simultaneously with the first transgre-
sive phase of the Holocene Transgression. The geo-
graphic range covered by each depositional environ-
ments was evidently different from the prevailing
today (fig. 14).

The assemblages of foraminiferids are most suited to
reveal the location (situation) of the Transitional-area
between marine and fluvio-marine environments during
the earlier phase of the Holocene Transgression. It

COMPARISON BETWEEN HOLOCENE
AND PRESENT DAY ENVIRONMENTS

QUERANDINA
TRANSGRESSION

Fig. 14: Comparison between depositional environments
from the first transgressive phase of the Holocene Trans-
gression, and those of the present day, showing environ-
mental displacements. Key: 1 = inner-fluvial environment,
2 = intermediate-fluvial environment, 3 = fluvio-marine
environment, 4 = marine environment. a, b and c location
of transitional-areas (also see figs. 3 and 12).

formed an arch along the Uruguayan coast, extending
from Salinas as fas as San Jose de Carrasco, Areneras
de Carrasco, and the eastern coastal region of Monte-
video County. In contrast, the foraminiferids are not
useful in the reconstruction of the location of the
remaining transitional-areas. By evaluating mollus-
can assemblages, reconstruction of the geographical
setting of fluvio-marine and intermediate-fluvial envi-
ronments was possible. The Transitional-area be-
tween fluvio-marine and intermediate-fluvial environ-

ments was located between Carmelo and Nueva Pal-
mira. The transitional-area between intermediate-
fluvial and inner-fluvial environments was localized in
the Rio Uruguay somewhat to the north of Fray
Bentos; and a little east from Mercedes on the Rio
Negro (fig. 12).

The depositional environments and transitional-
areas were reconstructed using foraminiferal and mol-
luscan assemblages found on the Uruguayan coast of
the Rio de la Plata. Their projection towards the
central and southern estuarine region is tentatively
outlined.

The great extent of the movement of the depositio-
nal environments shown in Fig. 14 shows that they
could not had occured as a consequence of a saline
stratification.

Paleogeographical reconstruction has confirmed the
validity and authenticity of the argument that the
foraminiferal and molluscan associations were depos-
ited during the earlier Holocene transgressive events.
URIEN & OTTMANN (1971) wrote that the transgressive

events during the upper Holocene had less vertical
amplitude and smaller superficial extent. Further-
more, the marine influence remains restricted to the
outer part of the estuary.

These results are also in agreement with those of
URrıeEn (1972), who by using sedimentological methods
showed the existence of:

1. an onlap of marine sandy facies during the Que-
randina Transgression, which was followed by,
2. an offlap of fluvial sitly muddy facies.

The sea also invaded the Laguna Merin area simul-
taneously to the Querandina Transgression. It was
connected with the ocean by it southernmost part.
Jost, SoLıanı Jr. & GopoLrHIn (1975) previously
described the existence of a second connecting body
designated the “Vertedouro do Taim”. The mollus-
can assemblages of the Querandina Transgression
reveal in the Laguna Merin region the existence of
zonation, beginning in the south with marine environ-
ments, that gradually change north into fluvio-marine
and intermediate-fluvial environments.

VIZECONGLUSIONSABOUT THE
NEOGEN-QUATERNARY
EVOLUTION IN IIIE CELUN
AREA

Chuy well N°® 364 is located in the western region
of the Pelotas Basin. This well presents the most
complete known sedimentary sequences for the study
of the Uruguayan Neogene and Quaternary. This
fact explains the repeated studies made about this
bore-hole, and justifies the inclusion of a special
review of this well. Several stratigraphic interpreta-
tions were made for the well (see Chapter V-B).
Only the interpretation proposed by Goso (1972)
shows good parallelism with the distribution of fossil
assemblages. For this reason it is used as a basic
reference for the stratigraphic interpretation.

The drill cuttings situated between 133.00—
113.00 m (fig. 2) had been assignedtothe Camacho
Formation (EcocHArn, 1970; FiGuUEIRAS &
Broccı, 1971, 1972/73; Goso, 1972; MEDINA, 1962).
The depositional environments corresponding to these
drill samples are analysed in Chapter V-F-4. The
assemblages show a Miocene age.

Between 113.00—66.00 m continental sedimenta-
tion took place that lithostratigraphically corresponds
to the Raigön Formation (Goso, 1972).
Probably it was deposited during the Pliocene.

The Quaternary sequences of Chuy N° 364 which

contain foraminiferids and molluscs are analyzed in
Chapter VI. Its distribution shows that between
66.00—57.60 m only the bivalve Erodona mactroides
occured. This species is also present between 57.60—
54.20 m associated with foraminiferids, ostracods and
barnacle plates. The whole assemblages found be-
tween 66.00—54.20 m shows a shallow, cold tem-
perate, and hyposaline (oligohaline, mesohaline) depo-
sitional environment.

Between 50.00—30.00 m assemblages made up of
foraminiferids, ostracods, barnacle plates and bivalve
fragments are present. Their faunal spectrum indicate
shallow, cold temperate, and hyposaline (polyhaline-
mesohaline) waters.

Goso (1972) points out that these transgressive
episodes correspond lithostratigraphically to the Chuy
Formation. He also refers to the same formation the
drill samples which lie between 27.40— 7.10 m. These
three sequences which are part of the entire lithostra-
tigraphic Chuy Formation, were named Chuy I,
Chuy II and Chuy III.

The Chuy Formation was defined by DELANEY
(1963, 1965). Only the sediments Iying between
27.40—7.10 m are the same of those found in the type

locality of the Chuy Formation. The lithofacies of
the Chuy Formation were described by DELANEY
(1963, 1965, 1966, 1967, 1969?) and Jost (1972). The
sequence situated between 27.40—7.10 m, whose
lithofacies is equivalent with that of the Chuy Forma-
tion, is herenamedChuy (sensu stricto)III
(fig. 2). Probably it belongs to the upper Pleistocene
(see Chapter VI-C-3).

The drill cuttings found between 66.00—54.20 m,
and 50.00—30.00 m, lithologically are not similar to
the facies of the Chuy Formation sensu stricto. For
their identification the Chuy (sensu
lato), L and Chuy (sensu lato). II are
used (fig. 2). Its position in the section indicates that
they were deposited probably during the Pleistocene.

According to Goso (1972), the continental strata
that were deposited after each one of the chronostrati-
graphic events Chuy (sensu lato) I, Chuy (sensu lato)
II, and Chuy (sensu stricto) III, belong lithostrati-
graphically to the Libertad Formation. Each of these
continental events are chronostratigraphically named
Libertad I, Libertad II, and Liber-

names

tad III. Libertad III ist considered to be a
synonymfor Dolores Formation (fig. 2).

Goso (1972) correlated the Chuy I, Chuy II and
Chuy III events with the first, second and third
Quaternary interglaciations, respectively. Libertad I,
Libertad II and Dolores were considered as being time
equivalent with the second, third and fourth glacia-
tion, whereas Raigön is considered to have been
deposited during the first glaciation. ECOCHARD
(1970) also established time-stratigraphic correlations
between the sedimentary sequences of Chuy N° 364,
and the Quaternary glaciations and interglaciations.
Trıcarrt (1972) also provided time-stratigraphic corre-
lations between the Quaternary glaciations and inter-
glaciations and the Uruguayan formations. But the
correlations proposed by these authors do not in
themselves agree.

In this work none of these criteria has been adopted.
There is no objective evidence for dating, even less to
verify time-stratigraphic correlations with certain gla-
ciations or interglaciations.

MINSDISERTIBUTLON ORZTEIE
PATEOZOOGEOGRAPFIEAL
EIETORAE PRONINEES

The paleozoogeographical evolution of the region in
study, since the Miocene up to the Holocene, is very
controversial.

One of the most polemic aspects was postulated by
IHERING (1927). He theorized that the Gulf of
Mexico-Caribbean area was connected with the South
Atlantic by an arm of the Tethys crossing through the
continent and providing tropical waters. This hypo-
thesis has been examined from different points of
view. In reference to foraminiferids it has been dis-
cussed by Borrovskoy (1958, 1973, 1976), BoLTov-
skov & Lena (1971, 1974b), Cross (1963) and
MALUMIAN (1970).

In this chapter an attempt is made to make a
paleozoogeographical contribution with a different
point of view. The relationships between the distri-
bution of the marine currents and the paleozoogeo-
graphical littoral provinces that they determine are
analyzed from the Miocene to Holocene. This
paleozoogeographical zonation must be considered the
first approach to this subject for this region. It must
be completed and adjusted on the basis of new fossili-
ferous findings and the use of other phyla.

The evaluated data have been provided by:

a.the fossil assemblages found in Uruguayan bore-
holes; and

b. the interpretation of available information con-
tained in previous literature.

This analysis presents difficulties as a consequence
of the low number of known fossil localities. In addi-
tion, great disagreement exist in reference to the time-
stratigraphic relations of the Miocene assemblages re-
corded from the South American atlantic region.
This fact has been documented by Berrteıs (1975),
BERTELS & MADEIRA-FALCETTA (1977), BOLTOVSKOY
(1973), Cross (1967, 1970), MAarumIan (1970), MA-
LUMIAN & Masıuk (1973), Nocuri (1975) and STAIN-
FORTH (1975). This problem is even more acute in the
Quaternary.

The distributional pattern of the littoral foramini-
ferids from the atlantic coasts of South America since
the Miocene, can be explained by the existence of two
marine currents; one flowing from north to south
carrying warm masses, and another that flowing in the
opposite direction, transporting cold water bodies. It
is assumed and hypothesized that these currents are
the Brazilian and the Malvin respectively. Therefore,
the information offered by the foraminiferal associa-
tions of the wells, can be related to the present-day

distribution of the littoral zoogeographical provinces
in this region. The term littoral is used in the broad
sense. It includes the intertidal zone and the upper
part of the sublittoral zone (upper sublittoral zone).

The present distribution of the West Indian Pro-
vince (= Caribbean or Antillean Province) in South
America, and its division into subprovinces is des-
cribed by Borrovskoy (1964, 1965, 1976), BoLTov-
skoyr & WRIGHT (1976), and Tınoco (1971), (fig. 15c).
The features of the Argentine Province (= “king-
dom” of Buccella peruviana, s. |. or South American
Atlantic Province) were given by BoLtovskoy (1970a,
1976) and BoLrovskoy & WRIGHT (1976), (fig. 15c).

A. Miocene

Studies on the paleogeography of the Entrerriana
Transgression are provided by Harrıngron (1962)
and CamacnHo (1967).

The Miocene foraminiferal assemblages found in

Chuy N° 364 (133.00—122.10 m) are characterized
by the presence of Amphistegina gibbosa. At the
present time, Amphistegina radiata (and/or Amphi-
stegina lessonii) is the most characteristic foraminiferid
from the littoral and upper sublittoral warm waters of
nordeast Brazil. Its present range of distribution is
situated between the 23° S and 4° N parallels. This
species disappears north of Cabo Orange, and south of
Cabo Frio, and defines the North-brazilian Subpro-
vince (Tmoco, 1971). In this subprovince tropical
waters of the Brazilian current are found and the cold
Malvin stream has no influence. It is a region of tropi-
cal warm waters, with mean annual temperatures
higher than 24° C (BarecH, 1954). The surface-water
temperatures range between 24°C in february and
21° C in august (BoLTovskoy, 1976, fig. 2).

The presence of Ampbistegina gibbosa in the Chuy
area during the Miocene, indicates that the North-
brazilian Subprovince possessed a geographical distri-
bution which extended further south, reaching al least
34° S latitude (fig. 15 a).

PALEO- AND ZOOGEOGRAPHICAL LITTORAL

PROVINCES USING FORAMINIFERAL DATA

“

MIOCENE ..

E55 North - brazilian
Subprovince

Fig.15: Distribution of paleozoogeographical littoral provinces from Miocene to Holocene, based on foraminiferids.

1] South-brazilian
Subprovince

V North- i
DIE

Toop (1976, p. 388) also said that during the Eocene
and Miocene Ampbhistegina significantly reach a
greater geographic area than in modern seas. This
may be related in part to the warmer climates during
those times, and in part to the possibility of different
positions of the continents to the equator and to the
influence of oceanic currents.

These data are coincident with a pantropical
expansion of certain shallow-water foraminiferids,
specially seagrass-dwelling forms, that took place
during the lower and middle Miocene. This is cor-
related with a climatic amelioration of 5—8° C that
occured in higher latitudes of the southern hemisphere
during early and middle Miocene times (BRASIER,
1975b, p. 693695).

The existence of warm water bodies in the Brazilian
Miocene has also been shown for the Pelotas Basin
(Cross, 1966a, 1967, 1970), the Maraj6 Basin (PETRT,
1954) and the Pirabas Basin (PErrı, 1957). In these
fossiliferous localities Amphistegina is also present.
Therefore all these regions must be included in one
paleozoogeographic unit, which is designated as
North-brazilian Miocene Subpro-
vince (fig. 15a). The concept “paleozoogeogra-
phic province“ is used to signify a climatic unit. This
is a consequence of the fact that temperature is the
most important factor limiting the geographic range
of the species distribution (BorLrovskoy, 1965; BoL-
TOVSKOY & WRIGHT, 1976; VALENTINE, 1963).

In Argentina, the microfaunas from the Entrerrien-
se and/or Paranense (upper Miocene-lower Pliocene?)
of the Salado Basin, indicate somewhat higher tem-
peratures than exist today in this region (MALUMIAN,
1970; Marumıan & Masıuk, 1973). Amphistegina
is absent. BERTELS (1975) considered that the ostra-
cods from the Argentinian Entrerrian Stage (= En-
trerriense) indicated warm temperate waters. Based
on these evidences, it is thought that warm temperate
waters from the Entrerriense of Argentina correspond
with those of the South-brazilian Subprovince.
Today this subprovince is characterized by the pre-
sence of warm temperate water bodies, the influence of
the Brazilian current prevailing on the Malvin. For
this unit the name South-brazilian Mio-
cene Subprovince is proposed. These results
complement those of GrooT et al. (1967, p. 215).
They indicated that the subtropical zone of conver-
gence was situated, at least during the lower and
middle Tertiary, somewhat further south than today.

These results obtained for the marine faunas agree
with the paleoclimatological reconstructions made for
continental areas. MELENDEZ (1971) showed that
in the Miocene tropical floras prevail at this latitude.
VOLKHEIMER (1971) indicated that in the Pampas
region during the Miocene a very warm climate
existed, and in Patagonia temperate temperatures.

The existence of warm water bodies in the Uruguay
nearshore shelf during the Miocene must have had
consequences for the distribution of the gastropods
and bivalves. For the analysis of Miocene malacolo-
gical assemblages from Uruguay, a comparison is
made with their present range of distribution.

The influence of the marine currents on the distri-
bution of the present day molluscs from Uruguay was
studied by Sıcarnı (1967), who described the distribu-
tional range of 81 gastropod species, and 73 bivalves
species. These are classified into:

1. species reaching this region by influence of the
Malvin Current;

2. species belonging to the Brazilian current;
3. autochthonous ones.

There is a direct relationship between both men-
tioned currents and the zoogeographical provinces
defined on the basis of the molluscan assemblages
(BALECH, 1954; CARCELLES, 1944; CASTELLANOS, 1967;
ForTı, 1969; Sıcarpı, 1967). The Magellanic Pro-
vince is related to the influence of the cold Malvin
current; the Caribbean or Antillean is characterized
by the presence of the warm Brazilian current; and
the autochthonous species correspond with the Argen-
tinian or Patagonian Province.. The boundary be-
tween the Caribbean and Argentinian Provinces lies
approximately in the 28° S latitude. 'The boundary
between the latter and the Magellanic Province is
situated at the 43° S latitude (fig. 16a).

CARCELLES (1944) found that bathymetric zonation
isalso present in the distributional pattern of mol-
luscs. The species from the Caribbean or Antillean
Province possess for the most part a more superficial
distribution. In middle depths the autochthonous
species are most frequently represented, whereas in
deeper water the number of species belonging to the
Magellanic Province increases. Evidently this bathy-
metric zonation is determined by the distribution of
the marine currents. The water that is carried by the
Brazilian current lies in a more superficial position
than those transported by the Malvin current. Simi-
lar results were obtained and supported by the study
of foraminiferids. On the coastal areas the Brazilian
and autochthonous species are dominant, whereas
outside of the 80 m isobath the typical species of the
Malvin current prevail (BoLrovskovy, 1965, 1973,
1976; BoLTovskoyY & WRIGHT, 1976). This is inter-
esting because they allow errors to be avoided in
paleogeographical interpretation. In each association
from the different zoogeographical provinces the
percentile occurence of the individual species is deter-
mined not only by the latitude, but also by the
bathymetry.

The zoogeographical littoral provinces, defined on
the basis of foraminiferids and molluscs, disagree

somewhat in their conventional boundaries. But the
criteria used for their definition are the same, since
they are based on the interaction between the Malvin
and Brazilian currents. Hence the comparisons that
follow are legitimate.

Based on the data of Sıcarvı (1967, 1975) the per
cent occurence of the species given for the present day
Uruguayan gastropod and bivalve faunas is deter-
mined. The gastropod fauna is composed of
37/0 of the species related to the Brazilian-Antillean
influence, and therefore brought by the Brazilian cur-
rent; 17°/o are related to the Malvin current; 46°/o
are autochthonous (fig. 16b). The bivalve fau-

Earre

"Jı GASTROPODA BIVALVIA

IM Caribbean or Antillean Province

na consists of 44°/o of the species attributed to the
Brazilian current, 20/0 of a Magellanic origin, having
been carried by the Malvin current, and the remaining
35 %/9 are autochthonous (fig. 16c).

For the paleozoogeographical interpretation the
Miocene molluscs found in Chuy N° 364 are evaluated
in relation to their present distributional range. Only
the surviving Miocene species are taken into
consideration; the extinct ones have been rejected,
because their paleozoogeographical distributional pat-
tern is controversial. The analyzed species are clas-
sified in reference to their present zoogeographical
distribution (table XIX).

PERCENTILE OCCURENCE

OF MOLLUSCS

MIOCENE

Argentine or Patagonian Province

ST Magellanic Province

Fig. 16:

Percentile occurence of Uruguayan Miocene and

Recent molluscs belonging to the Caribbean, Argentinian

and Magellanic Provinces.

TABLE XIX
Paleozoogeography of molluscs from Chuy No 364

Caribbean or Antillean
Province

GASTROPODA
Halistylus columna
Iselica anomala (+)
Olivancillaria urcens
BIVALVIA

Amiantis purpurata

Corbula caribaea

Diplodonta vilardeboana
(Cyrtopleura lanceolata ornata)
(Tagelus plebeius entrerianus)

Argentinian or Patagonian
Province

Olivella puelcha

Mactra bonariensis
Tivela (Eutivela) isabelleana

Cyrtopleura lanceolata ornata and Tagelus plebeius
entrerianus constitute extinct subspecies of species that
today live in the Caribbean Province. In Table XIX
they are placed between parenthesis to indicate that
their paleozoogeographical distribution is tentatively
established.

The number of Miocene molluscan species of Chuy
N’? 364 which can be evaluated is relatively low.
This could introduce a bias in the paleozoogeographi-

cal interpretation. Therefore Table XX was plotted
— using the same criteria — with the Miocene mol-
luscs found at Chuy N? 364 as well as additional
species of the Camacho Formation found in exposures
of the Colonia and San Jose Counties (FIGUEIRAS &
Brocsı, 1971, 1972/73). The percentile occurence of
the Miocene molluscs from the entire Camacho For-
mation belonging to the different provinces in shown
in Fig. 16d-e.

TABLE XX
Paleozoogeography of molluscs from the Camacho Formation

Caribbean or Antillean
Province

GASTROPODA

Halistylus columna
Iselica anomala (+)
Olivancillaria urceus
Epitonium aff. unifasciatum (+)
Dorsanum moniliferum
BIVALVIA
Amiantis purpurata
Corbula caribaea
Diplodonta vilardeboana
Adrana electa
Plicatula gibbosa
Crassostrea rizophorae (+)
Dinocardium robustum (+)
Labiosa (Raeta) plicatella (+)
(Cyrtopleura lanceolata ornata)
(Tagelus plebeius entrerianus)

Argentinian or Patagonian
Province

Olivella puelcha
Buccinanops gradatum
Buccinanops uruguayensis
Buccinanops duartei
Adelomelon brasiliana

Mactra bonariensis

Tivela (Eutivela) isabelleana
Nucula puelcha

Lithophaga patagonica (+)
Tellina (Angulus) gibber

The species are assigned to their provinces primarly
using the data of Sıcarnı (1967). The zoogeographi-
cal classification of species identified in Tables XIX
and XX with a plus (+) is supported by the data of
their present distribution as stated by FIGuEIRAS &
Brocscı (1971, 1972/73).

From the analysis in Tables XIX and XX and from
Fig. 16d-e a total and significant absence of Miocene
species belonging to the Magellanic Province is seen.
The gastropod and bivalve associations are exclusively
made up of species from the Caribbean and Argenti-
nıan Provinces. They indicate a predominance of
warm water bodies transported by the Brazilian cur-
rent, in latitudes located between the 34°—35° south
parallels.

The comparison between the percentile occurence
of the Miocene and Recent gastropod and bivalve
species shows that:

1. The percentile occurence of species belonging to
the Argentinian or Patagonian Province remains very
similar.

2. The incidence of Magellanic species in present day
Uruguayan faunas was a consequence of substitution
for the Miocene Caribbean or Antillean forms.

These paleozoogeographical results agree and con-
firm those given by the foraminiferids.
they offer an explanation for a reiterated observation.
Several mollusc species from the Entrerriense sea still
exist in the Caribbean region. The explanation for
this is that both regions were integrated during the
Miocene in the same paleozoogeographical province,
characterized by tropical waters.

Furthermore

B. Pliocene

In Uruguay marine Pliocene fossil faunas have not
been found. According to BERTELS (1975) and BEr-
TELS & MADEIRA-FALCETTA (1977) no marine Pliocene
sediments were found on the atlantic borderland of
South America.

CamacHo (1967) reported that Pliocene molluscs
from Patagonia indicate the prevalence of species

from temperate waters. They show a greater
influence of the Brazilian current in comparison to the
situation existing today in this region. The substitu-
tion of species of the Brazilian current by others of
polar origin began in the Pliocene, and have increased
primarily since the Pleistocene. In contrast Bor-
Tovskoy (1973) considers that the Pliocene climate
was colder than today. The characteristics and distri-
bution of the Pliocene floras are very similar to the
present (MELENDEZ, 1971).

C. Quaternary

Two different points of view exist with regard to
the Quaternary paleotemperatures which existed in
the temperate South American atlantic region.

Bornas (1957) and Paropız (1962) reject categori-
cally the existence of changes in the molluscan faunas
which could be related to climatic cycles during the
Quaternary.

In contrast, RicHarns & Craig (1963) and Rı-
CHARDS (1966) consider that the climate was colder
than the present one during Pleistocene glaciations,
particularly during the last glacial (Wisconsin).
Their conclusions are based on molluscs from the Ar-
gentinian shelf. Similar results are given by GRoOT
et al. (1967), supported by palynological studies, and
by diatoms; as well as by evaluation of foraminiferids
(BoLrovskoy, 1973).

The foraminiferal assemblages from the lower
Holocene of Uruguay, typically indicate cold tempe-
rate waters, similar to the biocoenosis of this area
(Chapter VI-F-2). They belong to the Argentinian
Province, or “kingdom” of Buccella pernviana, s. |.,
and particularly to the North-patagonian Subprovin-
ce. This zoogeographical unit is delineated by 32°—
41° S latitudes, and is characterized by the abundance
of Elphidium discoidale (BoLrovskoy, 1970a, 1976;
BorrovskoyY & WRIGHT, 1976). In this subprovince
the Malvin current is dominant, but subtropical in-
fluences still exist, determined by the Brazilian current.
Other studies made on Quaternary microfaunas of
foraminiferids and ostracods from this region agree
with these results, showing that the temperature was
similar to the present day (BERTELS, 1975; BoLTovskoY,
1959b; Cross, 1966a, 1970).

In contrast, the analyzed malacological assemblages
from the lower Holocene indicate mean annual tem-
peratures somewhat higher than those that exist
today. This conclusion arises from the analysis of the
percentile occurence of those species whose distribu-
tion is considered to be determined: 1. by the Brazilian
current; 2. by the Malvin Current; and 3. are
autochthonous forms.

The comparison between the present day assembla-
ges of molluscs (gastropods, bivalves and polyplaco-
phorids) and those of the wells and Lecocq shows, that
those from the Querandinense have a lower occurence
of species considered to belong to the Malvin current,
therefore from the Magellanic Province (table XXI.).
Similar results were reported by Fortı (1968, 1969)
studying malacological associations from the coastal
plain from southern Brazil, which are considered to
probably be from the lower Holocene. The data
given by FoRTI are expressed in percentages in Ta-
ble XXI. Fıcueıras (1962) reported that all mollus-
can species of the Querandinense from Uruguay are
still found in the present assemblages. They are clas-
sified in species correspoinding to the Caribbean,
Magellanic and Argentinian Provinces. Their per-
centile occurence is shown on Table XXI. Further,
this author indicates that the distributional range of
some species has changed. Several species, which lived
or were abundant during the Querandinense in the
Uruguayan region, are very rare today, or else are
found living somewhat farther north.

To what extent the percentages given in Table XXI
can be considered significant, depends on the following
features:

1. First of all on the accuracy of knowledge of the
distributional pattern of living molluscan species.
RıcHARDsS & Craıc (1963) and RıcHARDs (1966) point
out that for many species the available information
is inadequate.

2. The malacological assemblages from the lower Ho-
locene were deposited in shallow water environments.
As has been indicated, the species from the Brazilian
current today have a more superficial distributional
range than the autochthonous and Malvin ones. It is
very difficult to establish to what degree the given
percentages are determined by the paleotemperatures,
or whether they are only the consequence of a bathy-
metric selection.

3. The malacological assemblages found in the wells
allow only the study of faunal diversity, and are not
appropriate in analyzing the species dominance.

4. The risks formulated by HErm (1969, p. 87) are
inherent if a comparison is to be made between faunas
from different biotopes.

The results provided by molluscs and foraminiferids
found in the wells and Lecocq, are in disagreement
concerning the paleotemperatures which existed during
the Querandina Transgression. A possible explana-
tion for this discrepancy is that the bivalves, and the
majority of marine gastropods, have a free-swimming
trochophore and veliger larvae. On the contrary, the
benthic foraminiferids do not possess true pelagic
stages during their ontogenethic development. This
enables a greater potential speed in the migration rate
of bivalves and the majority of marine gastropods.

This difference is most evident during short-term
environmental changes, as those occuring during the
Holocene.

Taking all evidence into consideration the interpre-
tation that follows has to be considered tentative.
Probably during the Querandina Transgression, the
warm Brazilian current, in the Rio de la Plata region,
had a greater influence than today, with mean annual

water temperatures somewhat higher than at present.
Hence, the existence of warm climatic cycles during
the Holocene was repeatedly postulated (SCHWARZ-
BACH, 1974). This slight increase in the water paleo-
temperatures did not appreciably modify the distribu-
tion of the littoral paleogeographical provinces. The
faunas from Querandina Transgression, as well as the
present ones, belongtotheNorth-patagonian
Subprovince (fig. 15b).

TABLE XXI
Percentile occurence of molluscs belonging to zoogeographic provinces

Caribbean Argentinian Magellanic
or Antillean or Patagonian Province
Province Province

PRESENT DAY FAUNAS

Puerto Quequen (CARCELLES, 1944) 29 %/o 44 9/0 25 0/0
Uruguay (Sıcarpı, 1967) 39 0/0 41 %o 19 %/o
QUERANDINA TRANSGRESSION

Uruguay (present study) 34 0/0 55 %/o 10 %/0
Uruguay (FıGuEiras, 1962) 38 %/o 57 %o 40/0
Southermost Brazil (ForTı, 1969) 55 %/o 37 °o 6 %/o

The shown percentages in Table XXI include the
faunas of gastropods, bivalves and polyplacophorids.
No corrections were made for the number of species
attributed to each province by the authors listed. The
only exception is the zoogeographical classification of

the genus Anachis. The Anachis species referred to by
FiGuEiras (1962), Sıcardı (1967) and in the present
study, are grouped according to Sıcarpr’s (1975)
criterion.

DSENUNATSREFERENCE LIST

A. Foraminiferids

The Foraminiferids found in the wells and Lecocq are
listed alphabetically below citing the original description.
Additional references are often given for each of the
species. Where changes in classification have been made,
the reasons for these are discussed briefly.

Baggina sp.?

Bolivina compacta Sınesottom: Bolivina robusta BRADY var.
compacta SIDEBOTTOM, 1905, Manchester Lit. Philos, Soc.,
Mem., Proc., vol. 49, no. 5, p. 15, pl. 3, fig. 7a, b.

Bolivina cf lomitensis GaLLoway & Wiısster: Bolivina lo-
mitensis GaıLoway & Wısster, 1927, Journ.
Paleont. vol. 1, no.1, p.71, pl.11, fig.7a4, b. — Bo-
livina cf. lomitensis GaLLoway & WıssLer, BOLTOVskoY,
1954, Rev. Inst. Nac. Invest. Cienc. Nat. y Mus. Ar-
gentino Cienc. Nat. “B. Rivadavia”, Cienc. Geol., tomo
3, no. 4, p. 281, pl. 26, figs. 3a, b, 4.

Bolivina striatula Cusuman: Bolivina striatula CusHMAn,
1922, Carnegie Inst., Publ. no. 311 (Dept. Marine Biol.,
Papers, vol. 17) Washington, D. C., p. 27, pl. 3, fig. 10.
— Bolivina Striatula Cushman, BoLTovskov, 1954, p.
190, pl. 13, fig. 12a, b, 13a, b, 14a, b, 15a, b, 16a, b.

Bolivina cf. variabilis (WırLıamson): Textularia variabilis
WiLLIıaMson, 1858, On the Recent foraminifera of Great

Ammonia beccarii (LiNNAEUS) var. parkinsoniana D’ORBIG-

nv: Nautilus beccarii LinnAcus, 1758, Systema naturae.
Ed. 10. Holmiae, impensis L. Salvii, tomus 1, p. 710,
pl. 1, fig. 1a—c, pl. 19, figs. h—h, i—i.
Ammonia beccarii (Lınn£), SCHNITKER, 1974, Journ.
Foram. Res. v. 4, no. 4 :217—223, pl. 1. The variety
parkinsoniana is morphologically used according to the
criterion of BoLTovskoy (1957a, p. 58).

Amphistegina gibbosa D’Orsıcny: Ampbhistegina gibbosa
D’Orsıcny, 1839. In: Ramön de la Sagra, Histoire phy-
sique et naturelle de I’Ile de Cuba. A. Bertrand, Paris,
p- 120; pl. 8, figs. 1—3 (in Ibid., vol. 8). — Amphiste-
gina gibbosa D.’ORBIGNY, HOFKER, Sr., 1969. Studies

fauna Curagao other Caribbean islands, vol. 31, no. 115,
p- 81, figs. 235 —237.
See also: LArsen, 1976, p. 151.

Britain. Ray Soc., London, p. 76, pl. 6, figs. 162—163.
— Bolivina variabilis (WıLLıamson), BoLTOVskoY, 1954,
p- 137, pl. 12, fig. 13a—c.

Buccella peruviana (D’ORBIGNY), sensu lato: Rosalina peru-
viana D’ORBIGNY, 1839, Voyage dans l’Amerique Me£ri-
dionale; Foraminiferes, tome 5, pt. 5, p. 41, pl. 1, figs.
12—14. — Borrovskoy, 1970a, p. 342.

Bulimina cf. affinis D’Orsıcny: Bulimina affinis D’OrBIGNY,
1839, Foraminiferes. In: Ramön de la Sagra, Histoire
physique et naturelle de !’Ile de Cuba. A. Bertrand,
Paris, p. 105; pl. 2, figs. 25—26 (in: Ibid., vol 8). —
Bolivina affinis D’Orsıcny (?), BoLTovskoy, 1954, p. 179,
pl. 10, fig. 18.

Buliminella elegantissima (D’Orsıcny): Bulimina elegantis-
sima D’ORBIGNY 1839, Voyage dans l’Am£rique M£ridio-
nale; Foraminiferes tome 5, pt. 5, p. 51, pl. 7, figs. 13—14.
— Buliminella elegantissima (D’ORBIGNY), BOLTOVSKOY,
1954, p. 173, pl. 8, figs. 9—10.

Cancris sagra (D’OrBıcnY): Rotalina (Rotalina) sagra
D’OrsıcnY, 1839, Foraminiferes. In: Ramön de la Sagra,
Histoire physique et naturelle de l’Ile de Cuba. A. Ber-
trand, Paris, p.77; pl. 5, figs. 13—15 (in Ibid., vol. 8).
— Cancris sagra (D’ORBIGNY), BOLTOVsKOY, 1957a, p. 59,
pl. 11, figs. 1a, b, 2a—c.

Cassidulina curvata PHLEGER & Parker: Cassidulina curvata
PHLEGER & PARKER, 1951, Geol. Soc. Amer., Mem. no. 46,
pt. 2, p. 26, pl. 14, fig. 5a, b.

Cassidulina laevigata D’Orsıcny: Cassidulina laevigata
D’ORBIGNY, 1826, Ann. Sci. Nat., Paris, ser. 1, tome 7,
p- 282, pl. 15, figs. 4—5, 5 bis.

Cassidulina subglobosa Brapy: Cassidulina subglobosa
Brapy, 1881, Quart. Jour. Micr. Sci., London, n. s., vol.
21, p. 60; pl.54, fig. 17a—c (in Brapy 1884, Rept. Voy.
Challenger, Zool., vol. 9).

Cibicides aknerianus (D’Orsıcny): Rotalina akneriana
D’ORBIGNY, 1846, Foraminiferes fossiles du bassin tertiaire
de Vienne (Autriche), p. 156, pl. 8, figs. 13—15. — Cibi-
cides aknerianus (D’OrBıGNnY), BoLToOVskoY, 1954, p. 213,
pl. 15, fig. 6a, b, pl. 18, fig. 8.

Cibicides “psendoungerianus” (Cusuman): Truncatulina
psendoungeriana CusHMan, 1922, U.S. Geol. Suv., Prof.
Pap., no. 129—E, p. 97, pl. 20, fig. 9. — Cibicides
“psendoungarianus” (CusHMAn), BOLTOVskoY & LENA,
1966, p. 291, pl. 2, fig. 4.

Dentalina communis v’Orsıcny: Nodosaria (Dentaline)
communis D’ORBIGNY, 1826, Ann. Sci. Nat., Paris, ser. 1,

tome 7, p. 254. — Dentalina communis D’ORBIGNY,
BorTovskoy, 1959a, p. 63, pl. 9, fig. 1.
Discorbinella® bertheloti, forma boneana (D’ORBIGNY):

Truncatulina boueana v’Orsıcny, 1846, Foraminiferes
fossiles du bassin tertiaire de Vienne (Autriche), p. 169,
pl. 9, fiıgs. 24—26. — Cibicides bertheloti (D’ORrBIGNY),
forma boneana (D’OrBIGNY), BoLTovskoy, 1959a, p. 106,
pl. 17, figs. 5a, b, 6.

Discorbis peruvianus (D’OrBıcnY): Rosalina peruviana
D’OrBIGNY, 1839, Voyage dans l’Amerique ME£ridionale;
Foraminiferes, tome 5, pt. 5, p. 41, pl. 1, figs. 12—14. —
Discorbis peruvianus (D’ORBIGNY), BOLTOVSKOY & LENA,
1966, p. 297, pl. 3, figs. 4—7.

Discorbis gr. vilardeboanus (D’OrsıcnY): Rosalina vilarde-
boana v’OrBıcnY, 1839, Voyage dans l’Ame&rique ME£ri-
dionale; Foraminiferes. Strasbourg, Levrault, tome 5, pt.
5, p. 44, pl. 6, figs. 13—15. — Discorbis vilardeboanus
(D’Orsıcny), BoLTovskoy, 1954, p. 201, pl. 14, fig. 9a—c.

Discorbis williamsoni (CHarMAn & PArr), forma praegeri
HERON-ALLEN & EArLAnD: Rotalina nitida WILLIAMSON,
1858, On the Recent foraminifera of Great Britain, Ray
Soc., London, p. 54, pl. 4, figs. 106—108. — Discor-

bina praegeri HERON-ALLEN & EARLAND, 1913, Proc. Roy.
Irish. Acad. vol. 31, no. 64, p. 122, pl. 10, figs. 8$—10.
— Discorbis nitidus (WıLLıamson), BoLTovskoy, 1957a,
p-. 55, pl. 9, figs. 1a—c, 2a—c, 3a—c, da—c, 5a-c, 6a-c.
— Discorbis williamsoni (Chapman & Parr), forma
praegeri HERON-ALLEN & EARLAND, BoLTovsKkoy, 1959a,
p- 89. According to LoEsLıcH & Tarran (1964, p. C578)
this species belongs to the genus Gavelinopsis HOFKER
being its type-species.

Discorbis gr. sp. “A” Bortovskoy: Discorbis sp. “A”, BoL-
Tovskoy, 1954, p. 203, pl. 15, fig. 4a, b.

Elphidium depressulum Cusnuman: Elphidium advenum
(CusHMAn) var. depressulum, CusHMAN, 1933, U. S. Nat.
Mus. Bull. 161, p. 51, pl. 12, fig. 4. — Elphidium de-
pressulum Cusuman, BoLTovsKoy, 1954, Rev. Inst. Nac.
Inv. Cienc. Nat. y Mus. Argentino Cienc. Nat. “B. Riva-
davia”, Cienc. Geol., tomo 3, no. 4, p. 276, pl. 25, figs. 3a,
b, 4a, b. — Elphidium advenum depressulum CusuMAn,
BoLrovskoy, 1959a, p. 96, pl. 15, fig. 4. — Elphidium
depressulum Cusuman, BoLTovskoY, 1976, p. 223.

Elphidium discoidale (d’Orsıcny): Polystomella discoida-
lis d’Orsıcny, 1839. In: Ramön de la Sagra, Histoire
physique et naturelle de l’Ile de Cuba. A. Bertrand, Paris,
p- 56; pl. 6, figs. 23—24 (in Ibid., vol. 8). — Elphidium
discoidale (d’Orsıcny), BoLrovskov, 1957a, p. 43, pl. 8,
figs. 1a, b, 2a, b, 3a, b, 4a, b, 5a, b.

Elphidium gr. excavatum (Terquem): Polystomella exca-
vata TERQUEM, 1875, Soc. Dunkerquoise, M&m., Dun-
kerque, 1876, vol. 19 (1874—1875), p. 429, pl. 2, fig. 2a,
b. — Elphidium excavatum (TErQUEM), Cross, 1963,
p- 56, pl. 4, fig. 4, 7.

Elphidium galvestonense Kornreio: Elphidium gunteri Co-
LE var. galvestonensis KORNFELD, 1931, Stanford Univ.
Dept. Geol., Contr., vol. 1, no. 3, p. 87, pl. 15, figs. 1a, b,
2a, b, 3a, b. — Elphidium galvestonense KORNFELD,
Cwoss, 1963, p. 57, pl. 4, fig. 6, pl. 6, fig. 28a, b.

Elphidium gunteri Core [sensu Cross, 1963]: Elphidium
gunteri Couz, 1931, Florida State Geol. Surv., Bull., no. 6,
p- 34, pl. 4, figs. 9—10. — Elphidium gunteri CoLr,
Cross, 1963, p. 55, pl. 4, figs. 1—3, 5, 8, pl. 6, fig. 29a, b.
non: Elphidium günteri CoLe, RosseT-MOULINIER, 1976,
Revue Micropalöont., vol 19, no. 2, p. 92, pl. 1, figs.
10—11, pl. 2, figs. 1—4. In Rosser-Mouuinier a diffe-
rent species from the Bretagne coast is described under
the same species designation. As Rosser-MOULINIER does
not give references about the holotype, the concept of
Cross is adopted. — Elphidium guntheri Coe, Han-
SEN & LYKKE-ANDERSEN, 1976, p. 12, pl. 8, figs. 10—12,
pl. 9, figs. 1—3.

Elphidium aff. sagrum (d’Orsıcnv): Polystomella sagra
d’Orsıcny, 1839, In: Ramön de la Sagra, Histoire phy-
sique et naturelle de l’Ile de Cuba. A. Bertrand, Paris,
p- 55; pl. 6, figs. 19—20 (in Ibid., vol. 8).

Elphidium cf. tuberculatum (d’Orsıcny): Nonionina tuber-
culata d’Orsıcny, 1846, Foraminiferes fossiles du bassin
tertiaire de Vienne (Autriche) p. 108, pl. 5, figs. 13—14.
— Protelphidium tuberculatum (d’ORBIGNY), MALUMIAN,
1972, p. 116, pl. 4, fig. 4a, b. — Elphidium tuberculatum
(d’ORBIGNY), HANSEN & LYKKE-ANDERSEN, 1976, p. 14,
pl. 12, figs. 1—4.

Elphidium sp. A

Elphidium sp. B

Fissurina laevigata Reuss: Fissurina laevigata Reuss, 1850,
K. Akad. Wiss. Wien, Math.-Nat. Cl. Bd. 1, p. 366,
pl. 46, fig. la, b. — Borrovskoy, 1954, p. 157, pl. 11,
fig. 5a, b.

Flintinella sp.
Fursenkoina sp.

Guttulina plancii d’Orsıcny: Guttulina (Guttulina) plan-
cii d’Orsıcny, 1839, Voyage dans l’Am£rique ME£ridio-
nale; Foraminiferes, tome 5, pt. 5, p. 60, pl. 1, fig. 5. —
Guttulina plancii, d’Orsıcny, BoLrovskoy, 1954, Rev.
Inst. Nac. Invest. Cienc. Nat. y Mus. Argentino Cienc.
Nat. “B. Rivadavia”, Cienc. Geol., tomo 3, no. 4, p. 270,
pl. 23, fig. 5a—c.

Guttulina problema d’Orsıcny: Guttulina problema d’Or-
BIGNY, 1826, Ann. Sci. Nat., Paris, ser. 1, tome 7, p. 266,
no. 14. — Guttulina problema d’Orsıcny, CLoss & BAr-
BERENA, 1962, p. 31, pl. 2, fig. 8, pl. 6, fig. 8.

Lagena laevis (MonTAcu), forma perlucida (MoNTAGU):
Vermiculum perlucidum MontAcu, 1803, Testacea Bri-
tannica, or natural history of British shells, marine, land
and fresh-water, including the most minute. Romsey,
England, p. 525, pl. 14, fig. 3. — Lagena laevis (MoNTA-
cu), forma perlucida (Montacu), BoLTovskoy, 1959a,
p- 67, pl. 9, ig. 8.

Lagena sp.

Lenticulina limbosa (Reuss): Robulina limbosa Reuss, 1863,
Sitzber. kaiserl. Akad. Wissensch., math.-naturw. Cl.,
Wien, vol. 46, pt. 1, p. 55, pl. 6, fig. 69. — Robulus lim-
bosus (Reuss) s. |., BoLrovskoy, 1959a, p. 61, pl. 7, figs.
6,7.

Lenticulina rotulata (Lamarck): Lenticulites (rotulata) La-
MARCK, 1804, Mus. National Hist. Nat., Ann., Paris
(An 13), tome 5, p. 188; pl. 62 (14), fig. 11 (in Ibid.,
vol. 8, 1806). — Lenticulina rotulata LAMARcK, MALU-
MIAN, 1972, p. 111, pl. 3, fig. 8.

Massilina secans (d’Orsıcny): Quinqueloculina secans
d’Orsıcnv, 1826, Ann. Sci. Nat., Paris, ser. 1, tome 7,
p. 303. — Massilina secans (d’Orsıcny), BOLTOVskoY,
1957a, p. 26, pl. 6, fig. 1a, b, 2a, b, 3a, b, 4a, b, 5a, b.

Marginulina gr. tennis BORNEMANN: Marginulina tenuis
BORNEMANN, 1855, Z. Deutsch. geol. Ges., Berlin, vol. 7,
p. 326, pl. 13, fig. 14a, b.

Miliammina fusca (Brapy): Quinqueloculina fusca Brapy,
1870, Ann. Mag. Nat. Hist., London, ser. 4, vol. 6, p. 286,
pl. 11, figs. 2a—c, 3a, b. — Miliammina fusca (BrApy),
1963, Cross, p. 27, pl. 1, figs. 8-10, pl. 6, figs. 1a—c,
6—16.

Miliolinella subrotunda (MontAsu): Vermiculum subro-
tundum MonTaAcu, 1803, Testacea Britannica, or natural
history of British shells, marine, land and fresh-water,
including the most minute. Romsey, England, J. S. Hol-
lis, p. 521. — Miliolinella subrotunda (MonTAcu), Pon-
DER, 1974, Micropaleontology, vol. 20, no. 2, p. 201, pl. 1,
figs. 1a, b, 2a, b, pl. 2, fig. 6a—c, 7, 8a, b, 9a—i, 10, 11.

Nonion grateloupii (d’Orsıcny): Nonionina grateloupii
d’Orsıcnv, 1839, Foraminiferes. In: Ramön de la Sagra,
Histoire physique et naturelle de I’Ile de Cuba. A. Ber-
trand, Paris, p. 46; pl. 6, figs. 6—7 (in Ibid., vol. 8). —
Nonion grateloupi (d’Orsıcny), BoLrovskoy & LENA,
1966, p. 315, pl. 5, fig. 7. — Florilus grateloupi (d’Or-
BIGNY), ANDERSEN, 1975, Tulane Stud. Geol. Paleont.,
vol. 11, no. 4, p. 298, pl. 10, fig. 10. The genus Nonion
is used according to Hansen & LyKkKkE-AnDERSEN (1976)
point of view.

Nonion tisburyensis BUTCHER [sensu BoLrovskoy, 1958]:
Nonion tisburyensis BUTCHER, 1948, Cushman Lab. Fo-
ram. Res., Contr., vol. 24, p. 21, p. 22, tfs. 1—3. — No-
nion tisburyensis BUTCHER, BoLTovskoy, 1958, p. 18,
pl. 6, figs. 1a, b, 2—4, 5a, b, 6. The genus Nonion is

used according to Hansen & LYKKE-ANDERSEN (1976)
criterion.

Nonion sp. A.

Nonion sp. B.

Nonionella atlantica Cusuman: Nonionella atlantica CusH-
MAN, 1947, Cushman Lab. Foram. Res., Contr., vol. 23,
p. 90, pl. 20, figs. 44—c, 5. — Nonionella atlantica CusH-
MAN, BoLTovskoy, 1959a, p. 76, pl. 10, fig. 14a—c. —
Nonionella atlantica CusuHMAn, HANSEN & LyYkkE-AnN-
DERSEN, 1976, p. 23, pl. 21, figs. 9—12.

Nonionella auricula HERON-ALLEN & EARLAND: Nonionella
auricula HERON-ALLEN & EArLAND, 1830, Roy. Micr.
Soc., Jour., London, ser. 3, vol. 50, p. 192, pl. 5, figs.
68—70. — Nonionella auricula HERON-ALLEN & EAR-
LAND, BoLTovskoy, 1954, p. 167, pl. 7, fig. 9a—c.

Oolina melo d’Orsıcny: Oolina melo d’Orsıcny, 1839,
Voyage dans l’Amerique Meridionale, Foraminiferes,
Strasbourg, Levrault, tome 5, pt. 5, p. 20, pl. 5, fig. 9.

Poroeponides lateralis (TERQuEM): Rosalina lateralis TER-
QuEM, 1878, Soc. G£ol. France, M&m., ser. 3, tome 1,
no. 3, p. 25, pl. 2, fig. 11a—c. — Poroeponides lateralis
(TERQuEM), BorLrovskoy, 1957a, p. 59, pl. 10, fig. 5a—c.

Pyrgo nasuta Cusuman: Pyrgo nasutus CusHMAn, 1935,
Smithsonian Inst. Misc. Coll. vol. 91, no. 21 (publ. 3327),
p. 7, pl. 3, figs. 1a, b, 2—4. — Pyrgo nasuta CusHMAN,
Borrovskoy, 1957a, p. 30, pl. 4, fig. 9a—c.

Pyrgo ringens patagonica (d’Orsıcny): pars? Miliolites
(ringens) subglobosa LamArck, 1804, Mus. National Hist.
Nat., Ann., Paris, (An 13), tome 5, p. 351; pl. 17 (15),
fig. 1 (in Ibid., vol. 9, 1807). — Biloculina patagonica
d’Orsıcny, 1839, Voyage dans l’Am£rique ME£ridionale;
Foraminiferes, tome 5, pt. 5, p. 65, pl. 3, figs. 15—17. —
Pyrgo patagonica (d’Orsıcny), BoLTovskoy, 1954, p. 133,
pl. 3, fig. 3a—c, pl. 19, fig. 7a, b. — [pars] Pyrgo ringens
patagonica d’OrgBıGnY, BOLTOVSKOY & LENA, 1966, p. 326.

Quinqueloculina cf. agglutinata Cusuman: Quinqueloculina
agglutinata Cusuman, 1917, U.S. Nat. Mus., Bull., no. 71,
p- 43, pl. 9, fig. 2a—c. — Quinqueloculina cf. agglutinata
CusHMAn, BoLTovskoy, 1957a, p. 24, pl. 4, figs. 1, 2,
3a—c, 4.

Quinqueloculina angulata (WıLLıamson), forma typica: Mi-
liolina bicornis (WALKER) var. angulata WILLIAMSON,
1858, On the Recent foraminifera of Great Britain. Ray
Soc., London, p. 88, pl. 7, fig. 196. — Quinqueloculina
angulata (WıLLıamson), BoLTovskoy, 1954, p. 123, pl. 2,
fig. 1a—c. — Quinqueloculina angulata (WILLIAMSON),
forma typica, BoLTovskoY & LENA, 1966, p. 327.

Quinqueloculina atlantica BoLrovskovy: Quingueloculina
atlantica BoLrovskoy, 1957, Rev. Inst. Nac. Invest.
Cienc., Nat. y Mus. Argentino Cienc. Nat. “B. Rivada-
via”, Cienc. Geol., tomo 6, no. 1, p. 25, pl. 5, fig. 2a—c, 3,
4a—.c, 5, 6ba—c.

Quinqueloculina aff. frigida Parker: Quingueloculina fri-
gida PARKER, 1952, Mus. Comp. Zool., Bull., Cambridge,
vol. 106 (1951—1952), no. 9, p. 406, pl. 3, fig. 20a, b. —
Quinqueloculina aff. frigida PARKER, BoLTovskoY, 1957a,
p. 24, pl. 4, fig. 7a—c.

Quinqueloculina intricata TERQUEM: Quinqueloculina intri-
cata TERQUEM, 1878, Soc. G£ol. France, Mem., ser. 3,
tome 1, no. 3, p.73, pl.8, figs. 16a, b, 17a, b, 18a—c,
19a—c, 20a—c, 21a, b. — Quingueloculina intricata TER-
QUEM, WRIGHT, 1968, p. 250, pl. 2, figs. 1—4.

Quinqueloculina patagonica d’OrsıcnY: Quinqueloculina
patagonica d’Orsıcny, 1839, Voyage dans l’Ame£rique
Meridionale; Foraminiferes, Strasbourg, Levrault, tome 5,
pt. 5, p. 74, pl. 4, figs. 14—16. Quinqueloculina pata-

gonica d’Orsıcny, BoLTovskoy, 1954, p. 122, pl. 1, figs.
4a—c, 5a, b.

Quinqueloculina seminulum (LinnAzus): Serpula seminu-
lum LinnAgus, 1758, Systema naturae. Ed. 10. Holmiae,
impensis L. Salvii, tomus 1, p. 786, pl. 2, fig. la—c. —
Quinqueloculina seminulum (LinnAaEus), BOLTOVskoY,
1954, p. 120, pl. 1, figs. la—c, 2, 3a—c.

Quinqueloculina vulgaris d’Orsıcny: Quinqueloculina vul-
garis d’Orsıcny, 1826, Tableau methodique de la classe
des Cephalopodes. Ann. Sci. Nat., Paris, ser. 1, tome 7,
p- 302. — Quingueloculina vulgaris d’ORBIGNY, CusH-
MAN, 1929, U.S. Nat. Mus. Bull. 104, pt. 6, p.25, pl.2,
fig. 3a—c.

Quinqueloculina sp. A

Quinqueloculina sp. B

Quinqueloculina sp. C

Quinqueloculina sp. D

Quinqueloculina sp. E

Reophax artica Brany: Reophax artica Brapy, 1881, K.
Akad. Wiss. Wien, math.-naturw. Cl., Bd. 43, Abrh. 2,
P99s pl"25f1g52a,b.

Rosalina sp.?

Rotorbinella rosea (d’Orsıcny): Rotalia (Rotalie) rosea
d’Orsıcny, 1826, Ann. Sci. Nat., Paris, ser. 1, tome 7,
p- 272. Type fig.: Modeles, no. 35, 2me livraison. [PAr-
KER, JONES & Brapy, 1865, Ann. Mag. Nat. Hist., Lon-
don, vol. 16, ser. 3, pl. 3, fig. 79], d’Orsıcny, 1939, Fo-
raminiferes. In: Ramön de la Sagra, Hist. Phys. Pol. Nat.
Ile Cuba, p. 72, pl. 3, figs. 9—11. Rotorbinella rosea
(d’OrsBıcny), HOFKER, Sr., 1969, Studies Fauna Curagao
other Caribbean islands, vol. 31, no. 115, p. 85, figs.
247—250.

Textularia gramen d’Orsıcny: Textularia gramen d’OR-
BIGNY, 1846, Foraminiferes fossiles du bassin tertiaire de
Vienne (Autriche), p. 248, pl. 15, figs. 4—6. — Textula-
ria gramen d’Orsıcny, BoLTovskoy, 1957a, p. 19, pl. 2,
figs. 1a, b, 2a, b, 3a, b, 4a, b, 5a, b, 6a, b, 7a, b, 8a, b,
gab.

Textularia sp. A
Textularia sp. B

Triloculina sp.

B. Molluscs

An alphabetical list of species of bivalves, gastropods
and polyplacophorids found in the bore-holes and Lecocq
is given. In recent years several reviews of the systema-
tics of Neogene, Quaternary and living molluscs in this
area were published. FıcuEıras & Broccı have a paper in
preparation of taxonomic descriptions of species found in

the Vizcaino Formation, and include data from the wells
and Lecocg outrop. For this reason only the original and
present names of the recorded species are given, as well as
a reference to help in researching original bibliographic
sources.

1. BIVALVIA

Abra uruguayensis: Semele (Abra) uruguayensis PıLssry,
1897; FıguEiras & SıcarDı, 1969, p. 372, pl. 4, fig. 65.

Amiantis purpurata: Cytherea purpurata LAMARcK, 1818;
FıGuEiras & Broccı, 1972/73, p. 226.

Anomalocardia brasiliana: Venus brasiliana GmeLin, 1791;
FIGUEIRAS & SıcArDI, 1969, p. 363, pl. 4, fig. 49.

Brachidontes (Hormomya) darwinianus mulleri: Mytilus
mulleri Dunker, 1875; Fıcuzıras & SıcarpDı, 1968b,
p- 265, pl. 2, fig. 19.

Brachidontes (Brachidontes) rodriguezi: Mytilus rodriguezi
d’Orsicny, 1846; FiGuEiras & SıcarDı, 1968b, p. 266,
pl. 2, fig. 20.

Cardita (Carditamera) plata: Cardita plata Inzerınc, 1907;
Forrı, 1969, p. 78, pl. 3, fig. 3a, b.

Chione doello-juradoi: Chione doello-juradoi MEpına, 1962,
pl.1, fig. 1—2.

Chione meridionalis burmeisteri: Venus burmeisteri Bor-
CHERT, 1901; FiGuEiRAs & Broccı, 1972/73, p. 228.

Chlamys tehuelcha: Pecten tehuelchus d’Orsıcny, 1846, Fı-
GUEIRAS & SıcarDı, 1968b, p. 269, pl. 2, fig. 26.

Corbula caribaea: Corbula caribaea d’Orsıcny, 1845; Fı-
GUEIRAS & SıcarDı, 1970a, p. 409, pl. 5, fig. 75.

Corbula lyoni: Corbula lyoni PıLspry, 1897; FiGUEIRAS &
SıcArDı, 1970a, p. 410, pl. 5, fig. 77.

Corbula patagonica: Corbula patagonica d’OrsıcnY, 1846;
FıGuEiras & Sıcarpı, 1970a, p. 410, pl. 5, fig. 76.

Corbula pulchella: Corbula pulchella PruLirri, 1893; Fı-
GUEIRAS & Broccı, 1972/73, p. 232.

Crassinella guadalupensis: Crassatella guadalupensis d’OR-
BIGNY, 1842. In: Ramön de la Sagra, Histoire physique,
politique et naturelle de l’Ile de Cuba, p. 288, pl. 27,
fig. 21—23.

Crassinella maldonadoensis: Crassatella (Eriphyla) maldo-
nadoensis Pılsery, 1897; Forrı, 1969, p. 77, pl. 3, fig.
2a, b.

Cyrtopleura lanceolata ornata: Pholas ornata BORCHERT,
1901, FısuEıras & Broccı, 1972/73, p. 234.

Diplodonta vilardeboana: Lucina vilardeboana d’OrBIGNY,
1846; CAsTELLANOs, 1967, p. 243, pl. 18, fig. 7—9.

Erodona mactroides: Erodona mactroides Daupın, 1801;
Costa, 1971, p. 4, fig. 1—27.

Glycymeris longior: Pectunculus longior SowErsy, 1832;
Forrı, 1969, p. 70, pl. 2, fig. 2a, b.

Mactra bonariensis: Mactra bonariensis PruLıppı, 1893; Fı-
GUEIRAS & Broccı, 1972/73, p. 220.

Mactra isabelleana: Mactra isabelleana d’OrBıcnY, 1846;
CASTELLANOS, 1967, p. 237, pl. 21, fig. 9, 10.

Mactra marplatensis: Mactra marplatensis DoELLO-JURADO,
1949; CASTELLANOS, 1967, p. 234, pl. 21, fig. 11—13.

Mactra patagonica: Mactra patagonica d’OrBıcny, 1846;
CASTELLANOS, 1967, p. 235, pl. 21, fig. 1—3.

Mytilus platensis: Mytilus platensis D’OrBıGNnY, 1846; CAs-
TELLANOSs, 1967, p. 210, pl. 17, fig. 3, 4.

Ostrea equestris: Ostrea equestris Say, 1834; FIGUEIRAS &
SıcArnı, 1968b, p. 272, pl. 2, fig. 33.

Ostrea puelchana: Ostrea puelchana d’Orsıcny, 1842; Fı-
GUEIRAS & SıcarDı, 1968b, p. 271, pl. 2, fig. 32.

Pitar (Pitar) rostrata: Cytherea rostrata Koch, 1844; Ca-
MACHO, 1966, p. 81, pl. 18, fig. 1a—c.

Pleuromeris sanmartini: Pleuromeris sanmartini, KLAPPEN-
BACH, 1970, p. 36, fig. 1—5.

Plicatula cf. gibbosa: Plicatula gibbosa LAmArckK, 1801; Fı-
GUEIRAS & Broccı, 1972/73, p. 209.

Sphenia hatcheri: Sphenia hatcheri PıLserv, 1899; FIGUEIRAS
& SıcarDı, 1970b, p. 22, pl. 7, fig. 103.

Strigilla (Rombergia) cf. rombergü: Strigilla rombergiü
Mörch, 1853; Cox, NEwELL & Boy et al., 1969, p.
N 622; Strigilla rombergi MÖRCH, FIGUEIRAS & SICARDI,
1969, p. 375, pl. 4, fig. 71.

Tagelus plebeins: Solen plebeius SOLANDER, 1786; FIGUEIRAS
& SıcarDı, 1969, p. 369, pl. 4, fig. 60.

Tagelus plebeius entrerianus: Tagelus gibbus entrerianus
IHERING, 1907; FıGuEiras & Broccı, 1972/73, p. 224.

Tivela (Eutivela) isabelleana: Venus isabelleana d’Orsıcny,
1846; FıguEiras & Broccı, 1972/73, p. 225.

2. GASTROPODA

Acmaea subrugosa: Acmaea subrugosa d’OrBıcnY, 1841;
FIGuUEIRAS & SıcarDı, 1970c, p. 28, pl. 8, fig. 110.

Anachis isabellei: Nassa isabellei, d’Orsıcny, 1841; SICARDI,
1975, p. 106.

Anachis moleculina: Columbella moleculina Ducıos, 1840;
Sıcarnı, 1975, p. 104.

Anachis paessleri: Columbella (Seminella) paessleri STREBEL,
1905; Sıcarvı, 1975, p. 107.

Austroborus lutescens: Bulinus Iutescens Kıng & BRODERIP,
1832; FıGuEiras & Broccı, 1969, p. 349.

Buccinanops globulosum: Buccinum globulosum KıEner,
1834; CASTELLANOS, 1967, p. 90, pl. 7, fig. 5.

Buccinanops gradatum: Buccinum gradatum DeEsHayEs,
1844; CASTELLANOs, 1967, p. 92, pl. 7, fig. 6.

Crepidula aculeata: Patella aculeata GmELın, 1791; FıGuEi-
RAS & SıcarDı, 1971, p. 116, pl. 10, fig. 145.

Crepidula protea: Crepidula protea d’Orsıcny, 1835; Fı-
GUEIRAS & Sıcarnı, 1971, p. 116, pl. 10, fig. 146.

Diodora patagonica: Fissurella patagonica d’Orsıcny, 1841;
CASTELLANOS, 1967, p. 20, pl. 1, fig. 8.

Epitonium aff. unifasciatum: Scalaria unifasciata SOWERBY,
1844; FiIGUEIRAS & Sıcaroı, 1971, p. 109, pl. 9, fig. 132.

Halistylus columna: Halistylus columna Dar, 1889; Cas-
TELLANOS, 1967, p. 38, pl. 4, fig. 1.

Iselica anomala: Narica (?) anomala Anams, 1850; FıGuei-
RAS & Broccı, 1971, p. 140.

Littoridina australis: Paludina australis d’Orsıcny, 1835;
CASTELLANOS, 1967, p. 47, pl. 4, fig. 3.

Littoridina charruana: Paludestrina charrnana d’OrBıcnY,
1835; FıGuEiras, 1964, p. 175.

Ocenebra cala: Ocinebra cala PıLspry, 1897; FiGUEIRAS &
SıcarDı, 1972, p. 173, pl. 12, fig. 167.

Odostomia (Chrysallida) aff. jadisi: Odostomia (Chrysalli-
da) jadisi Oısson & Mc Ginty, 1958; FıguEiras & Sı-
cARDI, 1974, p. 334, pl. 19, fig. 242.

Olivancillaria urceus: Porphyria urceus Ropıng, 1798; Fı-
GUEIRAS & Brocsiı, 1971, p. 149.

Olivella (Olivina) puelcha: Oliva pnelcha, d’OrBıcnY, 1840;
FiGuEiras & Sıcarpı, 1973, p. 265, pl. 15, fig. 194.

Olivella (Olivina) tehuelcha: Oliva tehnelcha d’ORBIGNY
1840; FıGuziras & Sıcarpı, 1973, p. 265, pl. 15, fig. 195.

Parodizia uruguayensis: Parodizia uruguayensis NIEVES DE
Meoına, 1959, p. 53, 1 fig.

Polinices entrerriana: Natica entrerriana BORCHERT, 1901;
FiGuEirA & Broccı, 1971, p. 142.

Siphonaria (Pachysiphonaria) lessoni: Patella lessoni BLaın-
VILLE, 1824; CAMACHOo, 1966, p. 146, pl. 17, fig. 12a, b.
Tegula (Agathistoma) patagonica: Trochus patagonicus,

d’Orsıcnv, 1840; Forrı, 1969, p. 100, pl. 7, fig. 3a, b.

Triphora medinae: Triphora medinae Paronız, 1955; Fı-
GUEIRAS & Sıcarnı, 1971, p. 107, pl. 9, fig. 128.

Urosalpinx rushi: Urosalphinx rushi PıLsgry, 1897; CAsTE-
LLANOS, p. 77, pl. 5, fig. 8.

3. POLYPLACOPHORA

Chaetopleura isabellei: Chiton isabellei d’Orsıcny, 1841;
CASTELLANOS, 1967, p. 161, pl. 1, fig. 11.

X. SUMMARY AND
CONCLUSIONS

The ecology and paleoecology of the Uruguayan
coastal area was studied by Miocene, Pleistocene, Ho-
locene and present-day micro- and macrofaunal as-
semblages. They are:

Miocene assemblages. Marine Miocene faunas were
only found in well Chuy N° 364 between 133.00—
113.00 m. The associations are make up of benthonic
foraminiferids, molluscs, brachiopods, ostracods,

bryozoans, barnacle plates and additional microfossil
remains, all which are listed on Table II. They are
considered to be of Miocene age, using mainly paleo-
climatological data. This fact is supported mainly by
the distribution of Amphistegina gibbosa, as well as by
foraminiferal and molluscan associations. Time-
stratigraphic correlations with bore-holes from the
Pelotas Basin and Salado Basin were establisched and/

or confirmed. The depositional environments of these
strata were reconstructed using foraminiferids, and
indicate a normal marine nearshore environment, with
high energy warm waters. The substrate probably
had no sea flora cover. They were deposited during a
pregressive overlap. An analysis of microfaunal mi-
xing was made to find allochthonous foraminiferids.
The preservation of the foraminiferal tests is related to
the environmental parameters of the depositional
environments where they were found.

New data are given of the ecological distribution of
the present-day faunas of the Rio de la Plata estuary
and its zone of influence. They include:

Foraminiferids: The curve of REMANE for the
estuarine biocoenosis was plotted.

Bivalves: The curve of REMANE was reconstructed
evaluating data from living and dead assemblages.

Gastropods: Their distributional pattern was recon-
structed.

The genuine brackish-water and euryhaline mollus-
can species were identified, and the life habits of the
dominant genuine brackish-water species were esta-

blished.

Quaternary assemblages.. The foraminiferal and
molluscan assemblages found mainly in the bore-holes
were widely distributed along nearly 700 km of coast
line of the Rio de la Plata and Rio Uruguay, and
these are analyzed. The depositional environments of
strata bearing foraminiferids and molluscs were recon-
structed. Faunal associations indicate shallow and
cold temparate-waters. The depositional environ-
ments show great differences in salinity. The study of
the foraminiferids allowed one to be able to distin-
guish between the Quaternary Biofacies of Buliminella
elegantissima and the Quaternay Biofacies of Ammo-
This was made on
the basis of the percentile occurence of the dominant
species, as well as evaluating the capacity of the
genera to withstand changes in salinities. The fora-
miniferal associations show an estuarine environment
because they indicate a longitudinal distributional pat-
tern. Towards the head of the estuary the Quater-
nary Biofacies of Ammonia beccarii var. parkinsonia-
na replaces the Buliminella elegantissima one. The
environments of the innermost estuarine region were
reconstructed using bivalves and gastropods, using the
Curve of REMAnE, the identification of genuine
brackish-water species, the faunal composition and the
existence of vicariad species. Various criteria are
given for the identification of ancient estuarine
environments, and how they differ from other margi-
nal marine environments. Paleontological criteria are
also given in order to be able to distinguish between
the estuarine zonation existing along a longitudinal
axis, and its latitude.

nia beccarii var. parkinsoniana.

The early Holocene paleogeography in the Rio de
la Plata and its zone of influence was reconstructed. It
shows the existence of a displacement of the estuarine
depositional environments simultaneous to the Que-
randina Transgression. On the Uruguayan coastal
area, the marine environments penetrated inwards
towards the head of the estuary, being found as far
west as Arroyo Pando. The Transitional-area be-
tween marine and fluvio-marine environments formed
an arch along the Uruguayan coast, extending from
Salinas to San Jose de Carrasco, Areneras de Car-
rasco, and the eastern coastal region of Montevideo
County. The Transitional-area between fluvio-marine
and intermediate-fluvial environments was located be-
tween Carmelo and Nueva Palmira. The Transitio-
nal-area between intermediate-fluvial and inner-fluvial
environments was localized in the Rio Uruguay
somewhat to the north of Fray Bentos; and a little
east from Mercedes on the Rio Negro. Throughout
the course of the lower Holocene Transgression, the
Laguna Merin was directly open to the ocean at its
southernmost part. ‘The molluscan associations dis-
play a zonation from marine environments, to fluvio-
marine to intermediate-fluvial environments.

Biostratigraphic correlations were made using a new
method, i. e. ecostratigraphic units. These are cor-
related by their place within the cycle of greatest sali-
nity. Several assemblage zones previously described
for the Uruguayan Quaternary are invalidated.

The Neogene and Quaternary geological evolution
of the southernmost part of the Pelotas Basin was
analyzed. It is characterized by the alternation of
marine (or marginal marine) and terrestrial (continen-
tal) depositions. The following stratigraphic units
were recognized: Camacho, Raigön, Chuy (sensu
lato) I, Libertad I, Chuy (sensu lato) II, Libertad II,
Chuy (sensu stricto) III and Dolores.

The distribution and boundaries of the paleozoogeo-
graphical littoral provinces of the atlantic region of
South America since the Miocene were reconstructed
using foraminiferids and molluscs. Two Miocene lit-
toral units were identified, which are designated as:
1) North-brazilian Miocene Subprovince. This is
characterized by the existence of tropical water bodies,
extending at least from 34°—35° south latitude to
the north; 2) South-brazilian Miocene Subprovince,
characterized by warm temperate water bodies, which
extended south of the 34°—35° south latitude. The-
refore there is proof that tropical waters reached
1800 km further south along the eastern South Ame-
rican coast line during the Miocene than they do at the
present time. This is supported by the faunal com-
position of the Miocene foraminiferids of Chuy
N° 364, specially by the presence of Amphistegina
gibbosa. It is also confirmed by the study of bivalves
and gastropods from the entire Camacho Formation.

The gastropod and bivalve associations are exclusively
made up of species of the Caribbean and Argentinian
Provinces, the Magellanic forms being completely
absent.

The foraminiferal faunas of the Querandina Trans-
gression indicate cold temperate climes, similar to
those prevailing today. In contrast, the malacological
assemblages indicate mean annual temperatures
somewhat higher than those existing today in this
region. This is shown by the lower percentile occu-

rence of cold species carried by the Malvin current in
the malacological associations from the Querandina
Transgression. This difference is explained by the
greater potential speed in the migration rate of
bivalve larvae and the majority of marine gastropod
larvae. It is concluded that the faunas from the
Querandina Transgression, as well as the present ones
belong to the North-patagonian Subprovince. Pro-
bably the mean annual water temperature was
somewhat higher than today.

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EEE; München, 1. August 1978 | ISSN 0373 - 9627

The Osteology of Compsognathus longipes WAGNER

JOHN H. OSTROM*)

With 16 text figures and plates 7—14

ABSTRACT

Detailed analysis of the holotype specimen of
Compsognathus longipes — the classic or archtypical
“coelurosaurian“ theropod, does not substantiate the
traditional carnosaur — coelurosaur subdivision of the
Theropoda. Only in its diminutive size, is Compso-
gnathus a typical coelurosaurian. The smallest of all
known theropods, Compsognathus possesses a carno-
saur-like large skull (perhaps a juvenile condition); a
neck that is intermediate between the long cervical
series of coelurosaurs and the short neck of carnosaurs;
and forelimbs that are robust, but of intermediate
length and bear carnosaur-like two-fingered hands.
The hands, however, are unique among theropods,
with a peculiar phalangeal formula of 2-2-0 for dig-
its I, II and III. That condition excludes Compso-
gnathus from an ancestral relationship with any
known later theropod, as well as separating it from
other presently known Late Jurassic theropods. The

so-called impressions of integument and supposed skin
armor are judged to be nothing more than solution-
etched surfaces. The tiny skeleton preserved within
the body cavity of Compsognathus is identihable, and
proves to be a small individual of the lacertilian Bava-
risaurus (cf. macrodactylus), and not an embryo.
Analysis of those stomach contents indicates a very
long-tailed probably a highly cursorial
ground-dwelling variety. This remarkable evidence
establishes beyond any doubt that Compsognathus
was a very agile and fleet-footed predator. On the
basis of the unique construction of the hand, Compso-
gnathus appears to belong to a dead-end lineage
among theropods. On the same grounds, it is judged
to be somewhat removed from the theropod line that
earlier gave rise to Archaeopteryx, and ultimately to
later birds.

species,

KURZFASSUNG

Eine eingehende Analyse des Holotyps von Comp-
sognathus longipes, dem klassischen und archaetypi-
schen „coelurosauriden“ Theropoden, stützt nicht die
traditionelle Gliederung der Theropoda in Carnosau-
ria und Coelurosauria. Nur hinsichtlich seiner geringen
Größe ist Compsognathus ein typischer Coelurosau-
rier. Als kleinster bekannter Theropode besitzt Comp-
sognathus einen carnosaurierartigen, großen Schädel
(vielleicht ein juveniles Merkmal), einen Hals, dessen
Länge zwischen der langen Cervicalreihe der Coeluro-
saurier und dem kurzen Hals der Carnosaurier liegt
und Vordergliedmaßen, die kräftig, aber von interme-
diärer Länge sind, mit carnosaurierartigen, zweifinge-
rigen Händen. Das Handskelett ist jedoch einzigartig
unter den Theropoden und besitzt die eigenartige Pha-
langenformel 2-2-0 für die Finger I, II, und III. Die-
se Verhältnisse schließen Compsognathus von einer
Verwandtschaft mit irgendeinem bekannten, späteren

*) Prof. Dr. J. H. Ostrom, Dept. of Geology and Geophy-
sics, and Peabody Museum of Natural History, Yale Uni-
versity, New Haven, Conn., U.S.A.

Theropoden aus; ebenso trennen sie ihn von anderen
bis jetzt bekannten Oberjura-Theropoden.

Die sogenannten Hautabdrücke und der vermutete
Hautpanzer werden für nichts anderes als angelöste
Oberflächen gehalten. Das winzige, in der Leibeshöhle
von Compsognathus erhaltene Skelett ist mit Sicher-
heit als ein kleines Individuum des Lacertiliers Bava-
risaurus (cf. macrodactylus) zu bestimmen. Es ist
kein Embryo. Die Analyse dieses Mageninhaltes
deutet auf eine sehr langschwänzige Art hin, wahr-
scheinlich eine sehr schnelle, bodenlebende Form. Dies
erlaubt die bemerkenswerte Feststellung, daß Compso-
gnathus zweifellos ein sehr agiler und schnellfüßiger
Räuber war. Aufgrund der einzigartigen Konstruktion
der Hand, scheint Compsognathus im Hinblick auf die
Phylogenie der Theropoden zu einer blind endenden
Seitenlinie zu gehören. Es wird deshalb angenommen,
daß seine stammesgeschichtliche Position etwas abseits
von der Theropodenlinie lag, die früher zum Ur-
sprung von Archaeopteryx und letztlich zu den spä-
teren Vögeln führte.

TABLE OFICONTENTS

Abstract 73
Kurzfassung 73
Introduction . 74
Acknowledgements 75
Systematics 0 5 75
Stratigraphic and Locality De 78
General Description 78
Cranial Skeleton 81
Axial Skeleton : : 87
Appendicular Skeleton: ER Girdle and Boreltm Se rt
Appendicular Skeleton: Pelvis and Hindlimb . 94
Supposed Skin Armor of Compsognathus . BA 97
Comparison with other specimens referred to ehe: EEE en CL)
The supposed Embryo within Compsognathus 102
Compsognathus, the Animal Re: 108
The Munich Specimen, Adult or Juvenile? . 108
Reconstruction and Life Habits 109
Affinities of Compsognathus 113
Literature Cited 117

INTRODUCTION

For more than a century, Compsognathus has been
one of the better-known dinosaurs — partly, for
exactly the opposite reason that some other dinosaur
kinds are well-known: Compsognathus is the smallest
of all known dinosaurs. In life, it measured no more
than 70 to 75 cm from snout tip to tail tip. In texts
and popular writings, it has repeatedly been compared
in size with the common chicken. Compsognathus
also acquired fame because it was one of the first
dinosaurian specimens discovered that was virtually
complete, although, curiously enough, it was not orig-
inally identified as dinosaurian in the first report by
Andreas Wagner (1861) — perhaps because it was so
small, or because no one at that time really knew what
dinosaur anatomy should be like. But perhaps more
than anything else, the fame of Compsognathus was
caused by Thomas Huxley’s reference to it as a
“bird-like reptile“ in his speculations (1868, 1870) on
the relationship between birds and dinosaurs.

Since Wagner’s original description, this now classic
specimen has been studied by many prominent schol-
ars, including Huxley, Zittel, Marsh, Baur, Gegen-
baur, von Huene and others, and has been the subject
of several intriguing questions: the possibility of
viviparity in dinosaurs, and the evolutionary rela-
tionship between dinosaurs and birds.

Until 1972, when a second very similar but larger
specimen was reported (Bidar, Demay and Thomel)
from southern France, the Munich specimen was

unique. Except for three isolated “metatarsals“ and
an associated phalanx (Dames, 1884) sometimes refer-
red to Compsognathus, no other specimens have been
recovered from the Solnhofen Limestones, or else-
(But see page 101—102).

The present study is a consequence of several
factors: my persistent interest in dinosaurian biology
and evolution; the recently re-recognized (and now
reinforced) evidence of a probable dinosaurian origin
of birds; the often-cited bird-like nature of Compso-
gnathus; and finally, the need for a comprehensive
detailed study of this classic specimen.

where.

In the pages that follow, references are made to
specimens that are housed in various paleontological
collections. In those references, institutional names
are abbreviated as follows:

A.M.N.H. — American Museum of Natural Hi-
story, New York.

B.S.B: — Bayerische Staatssammlung für Pa-
läontologie und historische Geolo-
gie, Munich.

G.I.M. — Geological Institute of Mongolia,
Ulan Bator.

S.M.N.S. — Staatliches Museum für Naturkun-
de Stuttgart.

U.S.N.M. — United States National Museum,

Washington, D.C.

Y.P.M. — Peabody Museum of Natural Hi-
story, Yale University, New Ha-
ven.

Z.P.W. — Zaklad Palaeobiologii, Warsaw.

Acknowledgements

This study was possible thanks to the generous
invitation of Dr. Peter Wellnhofer and Prof. Dr. Ri-
chard Dehm, for me to spend my sabbatical year in
Munich as the guest of the Bayerische Staatssammlung
für Paläontologie und historische Geologie. I am
deeply grateful to Dr. Wellnhofer and Prof. Dehm for
their invitation, and for allowing me to study this
prize specimen of the Bavarian State collections. Iam

also grateful to them, and to Professors Volker Fahl-
busch and Dietrich Herm, for innumerable hospital-
ities and technical assistance which greatly facilitated
this research. Also, I wish to acknowledge the assist-
ance of the technical staff who provided preparational
and photographic services. Finally, and most impor-
tant, I wish to express my high esteem and sincere
gratitude to the Alexander von Humboldt Stiftung,
for the “Senior U. S. Scientist Award“ which made it
possible for me and my family to enjoy my sabbatical
year in Germany. This publication was made possible
by a generous gift from an anonymous friend of the
Bayerische Staatssammlung für Paläontologie und hi-
storische Geologie, and a grant from the ©. C. Marsh
Fund of the Peabody Museum of Natural History,
Yale University.

SYS: LE MALILGS

Class Reptilia
Order Saurischia Seeley, 1887
Suborder Theropoda Marsh, 1881
Family Compsognathidae Marsh, 1882

Definition: Small theropods with elongated
hindlimbs, medium length forelimbs and large skull.
Vertebral formula: 10 cervicals, 13 dorsals, 4 sacrals
and more than 20 caudals. Cervical vertebrae
opisthocoelous and pleurocoelous. Dorsal vertebrae
amphyplatyan or platycoelous. Cervicals not elong-
ated, rather approximating dorsal vertebral length.
Pelvis of normal triradiate (propubic) organization.
Pubis markedly longer than ischium and expanded
distally. Ilium long and low. Tibia significantly
longer than femur and metatarsals elongated. Tarsus
and pes of normal theropod construction with I re-
duced and reverted and V vestigial. Pes digital
formula: 2-3-4-5-0. Manus reduced to two functional
digits, Iand II, and vestigial metacarpal III. Digital
formula: 2-2-0- - . Skull relatively very large, equal
to or longer than femur. Two antorbital fenestrae
and very large orbit. Mandible very slender. Dental
3131510r.16.

18
distincetly “bent“, fang-like crowns.

count high: Anterior teeth with

Distribution: Malm of Europe: Solnhofen
Lithographic Limestones of Bavaria and the lithogra-
phic Portlandian limestone of “Petit Plan“, Canjuers,
France.

Included taxa: Compsognathus longipes

Wagner, 1861, holotype specimen: B.S.P. A.S. I
563; and Compsognathus “corallestris“ Bidar, Demay
and Thomel, 1972.

Discussion: The systematic history of Comp-
sognathus is rather interesting, especially as it relates
to the early development of dinosaurian systematics.
Although now widely viewed as the archtypical
“coelurosaurian“ dinosaur, curiously enough, Wagner
(1861) gave no opinion on its systematic placement
other than to refer to it as “einen Saurier“. Huxley
(1868) was the first to recognize that Compsognathus
should be “placed among, or close to, the Dinosauria“.
As is well-known, the term Dinosauria was coined by
Richard Owen (1842) as a reptilian order to encom-
pass various extinct giant reptiles that had been
unearthed in Britain. In 1887 and 1888, Seeley
demonstrated that the “dinosaurs“ then-known did
not constitute a natural group, and proposed two
distinctly different orders of dinosaurs — the Sauri-
schia and Ornithischia — orders that are still generally
accepted today. Asa result, the term “Dinosauria“
dropped from use as a formal taxon in classifications.
Between the proposals by Owen and Seeley, a number
of other schemes were proposed by various scholars.
The more important of these classifications are sum-
marized below:

Cope, Huxley, Marsh, Cope, Seeley,
1866 1870 1878—84 1883 1887
Orders Suborders Orders Orders Orders
Stegosauria

Orthopoda Ornithischia
Orthopoda Ornithopoda
Dinosauria Sauropoda Opisthocoela
Goniopoda Theropoda Goniopoda Saurischia
Symphopoda Compsognatha
Hallopoda

Of special interest here is Huxley’s classification,
which established a new order, Ornithoscelida, con-
taining two suborders, Dinosauria and Compsognatha.
His suborder Dinosauria included all then known
dinosaurs (Megalosauridae, Scelidosauridae, Iguano-
dontidae), including the Cetiosaurs (sauropods). The
suborder Compsognatha was proposed by Huxley to
include only Compsognathus, which he considered
close to the Dinosauria in its “ornithic modifications“,
but different from them in the relatively greater
length of the cervicals and a femur shorter than the
tibia. The taxon Compsognatha persisted as a higher
category of “dinosaurs“ as late as 1896, when Marsh
last listed it as a suborder of his order Theropoda.
Marsh’s classification of 1896 was as follows:

Class Reptilia
Subclass Dinosauria
Order Theropoda
Suborder Coeluria
Family Coeluridae
Suborder Compsognatha
Family Compsognathidaet)
Suborder Ceratosauria
Family Ceratosauridae
Family Ornithomimidae
Suborder Hallopoda
Family Hallopidae
Order Theropoda (No sub-ordinal assignments)
Family Megalosauridae
Family Dryptosauridae
Family Labrosauridae
Family Plateosauridae
Family Anchisauridae
Order Sauropoda (Six families)
Order Predentata (Equals Ornithischia)
Suborder Stegosauria (Three families)

1) Coincidentally, Marsh

Compsognathidae.

(1882) authored the family

Suborder Ceratopsia (One family)
Suborder Ornithopoda (Seven families)

Current traditional classifications subdivide the sub-
order Theropoda into two infraorders, Carnosauria
and Coelurosauria, the former including the large
carnivorous forms (Families Megalosauridae and
Tyrannosauridae) and the latter all of the smaller and
medium-sized theropods (Podokesauridae, Segisauri-
dae, Coeluridae, Compsognathidae, Ornithomimidae
and Oviraptoridae). Compsognathus has always been
allied with the Coelurosauria, ever since its inception
by von Huene in 1914. However, the general rela-
tionships among theropods have never been clear, and
this is reflected in the numerous classification schemes
and revisions of the Theropoda that have been pro-
posed over the years (see Huene, 1909, 1914, 1920,
1921 b, 1926, 1928; Osborn, 1917; Gilmore, 1920;
Matthew and Brown, 1922; Colbert, 1964; Charig,
Attridge and Crompton, 1965; and Colbert and
Russell, 1969).

In recent years, doubt has been expressed by some,
as to the validity of this two-fold subdivision of the
Theropoda. The discovery of Deinonychus (Ostrom,
1969a, 1969b), demonstrated once again that it is not
always a simple matter to assign a particular taxon to
one or the other of these infraorders. Deinonychus
possesses anatomical features that are usually con-
sidered exclusively carnosaurian or coelurosaurian,
but not common to both. Colbert and Russell (1969)
resolved this problem by placing the Dromaeosauridae
(including Deinonychus) in a third infraorder, Deino-
nychosauria. But the question remains: are the cate-
gories Coelurosauria and Carnosauria real and valid
categories? For example, ıf the size factor is dis-
regarded, can we justify them on purely anatomical
grounds? Deinocheirus (Osmolska and Roniewicz,
1970), on anatomical grounds is an ornithomimid —

the classic coelurosaurian family —, but an orni-
thomimid of enormous size. Because of its huge size,
Osmolska and Roniewicz placed it in its own family,
Deinocheiridae, and assigned it to the Carnosauria.
In 1972, I suggested that Deinocheirus was an over-
blown ornithomimid, but how could I justify placing
it in the Coelurosauria? I could not, and therefore
repeated the position I had taken earlier with Deino-
nychus; the infraordinal categories were omitted.

Most recently, Barsbold (1976) followed the same
principle, but with a different twist. He proposed yet
another revision of the Theropoda, wherein he recog-
nizes six infraorders: Coelurosauria, Deinonycho-
sauria, Oviraptorosauria, Ornithomimosauria, Carno-
sauria and Deinocheirosauria. This is comparable to
the systematics implicit in my 1969 and 1972 papers,
except that it is at a higher taxonomic level. Al-
though I am not comfortable with the elevated rank,
this arrangement, like my following “neutral” clas-
sification, simplifies some taxonomic assigments. At
least as presently known, there are no difficulties in
recognizing deinonychosaurs, oviraptorosaurs, orni-
thomimosaurs and deinocheirosaurss — if diag-
nostic remains are preserved. But if
only non-diagnostic elements of these are available,
we would be hard-pressed to assign them to any one
of these categories. But even here with Barsbold’s
“neutral” classification, the Carnosauria and Coe-
lurosauria still remain “mixed bags”, with the impli-
cation that the carnosaurian Megalosauridae and
Tyrannosauridae are more closely related to each other
than either is to any other theropod group, and that
all remaining small theropods (Segisauridae, Comp-
sognathidae, Podokesauridae, Coeluridae, etc.) are
likewise more closely related to each other. I prefer
not to make that systematic judgement at this time,
explicitly or implicitly. 'The data presented here on
Compsognathus may provide new insight, but at the
moment I believe that present evidence is inadequate
for final conclusions. For these reasons, the following
study is presented in the context of a conservative
classification as follows:

Class Reptilia
Subclass Archosauria
Order Saurischia?)

Suborder Theropoda
Family Podokesauridae
Family Compsognathidae
Family Segisauridae
Family Coeluridae
Family Dromaeosauridae
Family Ornithomimidae
Family Oviraptoridae

?2) The suborder Sauropodomorpha is included, but not
listed here.

Z40L

Family Megalosauridae
Family Tyrannosauridae

Missing from this classification is the Family Hal-
lopidae. The fragmentary (and only) specimen of
Hallopus (Marsh, 1881, 1882), long considered as pos-
sibly closely related to Compsognathus and other
“coelurosaurs”, has been shown by Walker (1970) to
be an early crocodilian. Thus, it is not considered
further here.

Although not directly pertinent to the systematic
placement of Compsognathus, two radical proposals
have been published recently, that do involve the
systematic assignment of the Theropoda. In 1974,
Bakker and Galton reviewed certain anatomical evi-
dence which led them to the conclusion that the
Ornithischia and Saurischia were of monophyletic —
common — ancestry, resurrecting Owen’s “Dino-
sauria”. Largely on their belief that all dinosaurs
were endothermic and capable of high aerobic exer-
cise metabolism (a popular, but unestablished hypo-
thesis), they concluded that the “Dinosauria” deserved
class rank. In their Class Dinosauria, the Theropoda
is elevated to ordinal rank (thus returning to Marsh’s
classification of 1884), within the subclass Saurischia.
Their most radical departure from conventional
systematics, however, is their inclusion of birds as a
subclass of the Dinosauria. This move was prompted
by my studies (Ostrom, 1973 and work then in prog-
ress — 1976b) showing that Archaeopteryx probably
was derived from a small theropod ancestor. Charig
(1976), in a thorough review of the Bakker and Gal-
ton paper, correctly concludes that “until the case for
endothermy in dinosaurs is proven (which is unlikely),
there are no grounds for separating those reptiles into
a different class from all others”. As for the inclu-
sion of birds as a subclass of Dinosauria, the possibility
that Archaeopteryx evolved from a theropod ancestry
(a theory that is not accepted by everyone), does not
justify such radical departure from conventional clas-
sification. Moreover, their proposal fails to enhance
the usefulness of the classification on either practical
or theoretical grounds, and therefore should be rejec-

ted.

Of greater relevance here, is a paper by Thulborn
(1975), which was generated by the Bakker — Galton
paper. Thulborn argues persuasively (as did Charig,
1976), that existing evidence does not establish mono-
phyly of the dinosaurs. He further rejects the specu-
lation that dinosaurs were endothermic, but he does
accept the theory that birds arose from theropods.
This last conclusion prompts Thulborn to re-assign the
Theropoda to the Class Aves, in order to put “full
emphasis on the dinosaurian origin of birds”. Desir-
able though that rationale may (or may not) be, clas-
sifying theropods such as Tyrannosaurus and Allosan-

rus as birds, will not add to the utility of vertebrate
classification either, and therefore will not be accepted
by the ornithological community or other systematists
— even if the therapod-avian evolutionary rela-
tionships should achieve general acceptance. The con-

ventional classification of the higher tetrapod classes
Reptilia, Aves and Mammalia is adequate and flexible
enough to accommodate these views, and I prefer to
use the conservative subdivision of the Theropoda
presented above, in the traditional Class Reptilia.

STRATIGRAPFIE
AND LOCALIEYEDATA

Unfortunately, considerable doubt exists about the
exact locality of Compsognathus longipes, with no
apparent way to resolve it. The oldest surviving doc-
umentary record of the existence of this specimen, is
Wagner’s (1861) original description, which describes
it as coming from the lithographic shales near Kel-
heim. A hand-written label glued to the underside of
the Compsognathus case reads: “Compsognathus long-
ipes Wagner — keine Eidechsen species — aus dem
lithographischen Schiefer — im Altmühlthal bei Kel-
The author of this label is unknown, but in
all probability, it was the original owner, a
Dr. Oberndorfer, a physician in Kelheim. However,
another, more recent printed label gives different
information. It reads: “Compsognathus longipes
Wagn. — (Orig. Ex. z. Wagn. Abh. Bd. IX T. 3) —
Lithograph. Schiefer. — Jachenhausen. Oberpfalz”.
Jachenhausen is a small village 15 km northwest of
Kelheim.

heim”.

No other records exist in the archives of the Bayeri-
sche Staatssammlung to explain these conflicting local-
ity data, or why or by whom the locality Jachenhau-
sen was first used. According to Professor Dehm, the
printed label dates from before 1900, possibly during
Zittel’s time, but the author is The
Oberndorfer collection was obtained by the Bayeri-
sche Staatssammlung in 1866, five years after Wagner
described Compsognathus. Besides the specimen of
Compsognathus, two other specimens of the Obern-
dorfer collection have labels with the same handwrit-
ing; a turtle Eurysternum crassipes and a pterosaur
Pterodactylus kochi. This suggests that Oberndorfer
probably authored these labels. The label for Eury-
sternum also reads “Kelheim”.

unknown.

It is presumed that Dr. Oberndorfer, as an amateur
collector, obtained his specimens from a number of
different Solnhofen quarries. It may be, that in order
to protect his sources from other collectors, he con-

cealed the precise localities under the general descrip-
tion “bei Kelheim”, and that the more specific
locality of Jachenhausen is the correct locality of
Compsognathus. But that is not supported by known
stratigraphic evidence. Professor Dehm informed me
that he attempted to identify the quarry site in the
Jachenhausen area from which this specimen might
have come. He was unsuccessful on two separate
attempts, and reported to me that he was unable to
find exposures of Solnhofen strata anywhere in the
Jachenhausen area that corresponded with the lith-
ology of the Compsognathus slab. Dr. Wellnhofer
and I also attempted to re-establish the source of the
Compsognathus specimen, and checked the large quar-
ries north of the town of Jachenhausen. We also
failed to discover any stratum that matched the lith-
ology of the Compsognathus slab. Most important, is
the fact that we failed to find a single specimen of the
ubiquitous crinoid Saccocoma (half a dozen specimens
of which are preserved on the Compsognathus slab)
anywhere in the Jachenhausen area. Thus, neither the
locality, or the stratigraphic provenance of Compso-
gnathus can be determined now. All that can be said
is that it came from lithographic facies of the Solnho-
fen Limestone — probably from somewhere in the
Riedenburg — Kelheim area.

In order that this report be as complete as possible,
it must be noted that both Marsh (1896) and von
Huene (1923, 1925, 1932 and 1956) published that
Compsognathus came from Solnhofen, but these seem
to have been general references to the area in which
the Solnhofen strata occur, rather than to the imme-
diate vicinity of the town of Solnhofen. At least
there is no surviving original record to substantiate a
Solnhofen locality, and it is assumed here to be incor-
rect. Steel (1970) is the only author to publish the
“Tachenhausen locality” as the source of Compso-
gnathus, presumably having obtained this information
from the printed label with the specimen.

GENERAL DESCRIPTION

The classic specimen of Compsognathus longipes is
well known, having been repeatedly illustrated and
cited in numerous texts, technical papers and popular
articles as the smallest dinosaur. Aside from its di-

minutive size (about that of a small partridge), it is
remarkable for the completeness and quality of pre-
servation. Although some regions are crushed, frac-
tured or disarticulated, most of the skeleton is present,

Preserved bone (Compsognathus)
ui Bone ıimpressions

Restored outline

Preserved bone (Small reptile)

R Be
ESS EEE An Cer Ri H
30 mm

ALL NA.

LDoRi9

SRT-2R1-2N
RMICHRI-N

RMICH.
{R Mic D)

SL I-IL 0-0

EPE
nd wi

"U D-IL 1-0) L 1-2 0-3)
\ R D-2(R D-3)

r
'
'

STIL D-2(L 1-2)

U Car?

Figure 1: Camera lucida drawing of the specimen of Compsognathus longipes, showing preserved bone and bone imp-
pressions, together with my identifications. The parenthetic identifications of the hand elements are von Huene’s (1925,
1926) interpretations for comparison with my interpretations of the same objects. The original drawing was made by me

with a Wild binocular microscope and camera lucida at a magnification of 3.3. Abbreviations: Ac. — acromion; An.
Cer. Ri. — anterior cervical rib; Ang. — angular; Art. — articular; Ast. — astragalus; At. Int. — atlas intercentrum; At.
L. Ne. — atlas left neural arch; At. R. Ne. — atlas right neural arch; Ax. — axis; Ax. N. S. — axis neural spine;

Br. C. — braincase; Ca. 1, 2, etc. — caudal vertebrae; Ca. n. S. — caudal neural spine; Cal. — calcaneum; Car. — carpal;
Ce. 3, 4, etc. — Cervical vertebrae; Cer. Ri. 4. — cervical rib 4; Co. — coracoid; De. — dentary; Do. 1, 2, etc. — dorsal
vertebrae; Do. Ri. 1, 2, etc. — dorsal ribs; Ep. — epipterygoid; Fe. — femur; Fib. — fibula; Fr. — frontal; Ga. — gastralia;
Hu. — humerus; Hy. — hyoid; Il — ilium; In. Den. — inter dental plates; Is. — ischium; Jaw — mandible; La. — lachrymal
L. — left; Max. — maxilla; Mt. — metatarsal; Mtc. — metacarpal; Na. — nasal; Pa. — parietal; Pal. — palatine;
Pm. — premaxilla; Po. — postorbital; Po. Cer. Ri. — posterior cervical rib; Pt. — pterygoid; Pu. — pubis; Q.— quadrate;
Qj. — quadratojugal; R. — right; Rad. — radius; Sa. 3, 4, etc. — sacral vertebrae; Sca. — scapula; Sp. — splenial;
Sur. — surangular; Ta. — tarsal; Tib. — tibia; Ul. — ulna; Vo. — vomer; I, II, III, IV, V. — digit number; 1, 2, 3, 4, 5.
— phalangeal number.

Figure 2:

either as actual bony elements or as impressions. A
few areas have been obliterated by calcite crystals,
especially in the lower part of the body cavity and the
pelvis, or removed by solution. Apparently, the slab
was situated close to the surface and subject to solution
by sub-surface runoff: the importance of this will be
discussed later. In spite of solution and crystalliza-
tion, most of the bones are finely preserved, apparent-

Q
IN

Restoration of the skeleton of Compsognathus based on the camera lucida drawing of Figure 1.

ly completely replaced by calcite with no recrystalli-
zation and consequent distortion and loss of detail
(see Plate 7.).

The specimen is preserved on its right side almost
completely articulated. The only regions that have
suffered some disarticulation are the hands, the skull,
some of the cervical ribs and the posterior gastralia.

Why these particular regions have been disarranged is
difficult to understand, although in the case of the
gastralia there is some evidence that the stomach and
body cavity were breached — perhaps due to build-up
of gases generated within the rotting carcass. The
posterior cervical ribs, the slightly displaced right
fibula and the scattered phalanges of the hands may
have been scattered by scavengers, but more likely
they simply were drifted away from their original
sites by gentle currents after connective tissues had
decomposed.

The most peculiar aspect is its “death pose” — the
highly contorted arrangement of the cervical series
and the respective positions of the axis, braincase and
dermal skull. The cervical column is looped back on
itself almost a full 360 degree arc. This opisthotonic
condition is not unusual, having been recorded in
numerous pterosaur specimens (especially pterodacty-
loids), small theropods (see, for example, Struthiomi-
mus altus, A.M. N. H. 5339, reported in Osborn,
1917, which is preserved in almost exactly the
same pose as Compsognathus) and modern birds. It
seems to be a common occurrence in carcasses of long-
necked animals; notice, for example, that it is much
less common in rhamphorhynchoid pterosaurs (than in
pterodactyloids) and short-necked theropods. The
most frequently invoked explanation of this backward
distortion of the neck is shrinkage (due to drying) of
the dorsal neck muscles and ligaments, particularly
the ligamentum nuchae. However, that presumably
requires that the carcass initially was exposed to sub-
aerial conditions and perhaps even mummified, before
being submersed, circumstances that are rejected by
Rietschel (1976) for the several specimens of Archae-
opteryx that are similarly contorted.

Whether or not desiccation is involved, contraction
of dorsal muscles and/or ligaments appears to be the
most probable explanation of this opisthotonic state.
But in the case of Compsognathus, we are faced with a
curious anomaly: the braincase and skull, to which
these ligaments and muscles were firmly attached, are
completely separated from the cervical column and
each other. The braincase has been displaced back-
ward, by more than its length, from the anterior end
of the axis (and rotated 90 degrees about its longitu-
dinal axis), while the dermal skull components have
been displaced even further backward, and turned
completely around (the braincase faces forward, but
the skull faces backward). As one of the largest and
strongest ligaments in the body, it seems unlikely that
the connection of the ligamentum nuchae to the skull
would have disintegrated before most other connective
tissues. Yet that appears to be exactly what hap-
pened. The entire axial skeleton, except for the atlas
and the skull, are preserved in close articulation.
How this happened is unknown. There is no evidence

that the head was severed by scavenger action and
currents strong enough to displace it surely would
have disarranged the skeleton as well.

As for the skeleton itself, it is well formed and gives
the impression of a fully developed individual (howev-
er, see later comments on this). The skull is relatively
very large, a possible indication of immaturity. The
neck is slightly shorter than the trunk. The caudal
series extend off the end of the slab, so tail length is
unknown. But from the very gradual reduction along
the proximal caudals, the original tail length must
have been more than twice as long as the preserved
caudal series. The hind limbs are extraordinarily long
and robust, while the forelimbs are of only medium
length. Compsognathus clearly was an obligate biped
and probably highly cursorial.

Cranial Skeleton
Skull.

Most of the skull and mandibles (see Plate 8) are
present, but somewhat disarticulated. Certain regions
are crushed and sufficiently damaged so as to make
reconstruction difficult and uncertain. The fact that
so many skull and jaw elements are separated from
adjacent bones, while there was relatively little dis-
articulation in the post-cranium, suggests that either
the skull was highly kinetic and very loosely bound
together, or that this is a young individual in which
the cranial elements had not yet become firmly united.
The very small size of the specimen, the seemingly dis-
proportionately long hind legs, and the relatively
large orbit, support the juvenile explanation. But the
fact that there are no textural differences, or differen-
ces in the degree of ossification between dermal and
endochondral bones, plus the fact that all vertebral
sutures apparently were closed, suggest that we are
dealing with a mature individual.

The skull, as I have reconstructed it, is quite long
(70—75 mm), very low and with a sharply tapered
snout. The orbit was very large and nearly circular.
Two antorbital fenestrae are present, one quite large
about half the size of the orbit, and the other small.
Both are sub-triangular in shape. The external nares
were narrow, elliptical, and somewhat elongated.
The temporal fenestrae have been obliterated by dis-
placement of some bones and loss of others, but the
lateral fenestra appears to have been quite high and
narrow from front to back. In general appearance,
the skull is most similar to that of Archaeopteryx. My
reconstruction of the skull is given in Figure 3.

A convenient index of head size is the ratio of skull
length to the length of the presacral vertebral column.
Using a skull length of 72 mm and a presacral length
of 235 mm, the ratio for Compsognathus is .30,
somewhat higher than most “coelurosaurs”, but not

Figure 3: Reconstruction of the skull and jaws of Comp-
sognathus longipes. 'The temporal region is largely hypo-
thetical, as are the sutural details between the maxilla, jugal
and lachrymal, the jugal and post-orbital, and the quadra-
tojugal, quadrate and squamosal. The number of teeth
shown is the absolute minimum, recording only those that
are preserved in place or are indicated by tooth impressions.
Empty alveoli due to tooth replacement or post mortem loss
cannot be distinguished. The diastema at the premaxilla —
maxilla suture is real.

significantly so. This higher ratio might be taken as
further evidence that this specimen was immature.
On the other hand, it might indicate a close affinity to
the larger-headed “carnosaurs”. A comparison of
skull / presacral ratios in several other theropods
with that of Compsognathus, is as follows:

Ornithomimus altus (A.M.N.H. 5339) . .15

Gallimimus bullatus (ZPW-MgD-194
&:CIM-DSP 10011) =. .0.8 has 216

Coelophysis longicollis (A.M.N.H. 7224) .23
Ornitholestes hermanni (A.M.N.H. 619) . .24
Allosaurus fragilis (U.S.N.M. 4734) . . .28
Compsognathus longipes (B.S.P. AS1563) .30

Deinonychus antirrhopus (Reconstruction,
various Y.P.M.) .35 - 40

Tyrannosaurus rex (A.M.N.H. 5027) . . .41

Not surprisingly, there seems to be an uninterrupted
gradation between so-called “coelurosaurs” and
“carnosaurs”. Notice that Compsognathus has a
ratio slightly greater than Allosaurus.

Premaxilla: Both premaxillae are present,
displaced and lying between the extremities of the two
dentaries. The lateral surface is exposed in both. The
premaxilla is roughly triangular in shape, deeply
emarginated posteriorly by the large external naris.
The nasal process is long and very slender and does not
appear to have been overlapped laterally or ventrally
by the nasal. 'The maxillary process (missing in the
right premaxilla) is much deeper and more robust.
The end of this process is concealed beneath the left
dentary, so the nature of the junction with the maxilla
cannot be determined. The external premaxillary

surfaces are smooth and devoid of even tiny foramina.
Premaxillary teeth number three, with the middle
tooth the largest. Two teeth are preserved in place in
the right premaxilla and a third lies slightly removed
from the empty posterior alveolus. Only the middle
tooth is preserved in place in the left premaxilla. A
long diastema occurs behind these teeth, the entire
maxillary process below the naris being devoid of
alveoli. Preserved as they are, Iying on their medial
surfaces, little can be said about the nature of their
mid-line articulation except that it must have been a
flexible union.

Maxilla: The nearly complete left maxilla is
displaced and lies below the rest of the skull and the
mandibles. This exposes the inner surface of the less
complete right maxilla situated close to its normal
position. The maxilla is a rather delicate and thin
bone with a surprisingly shallow tooth-bearing ramus.
The jugal process seems to have tapered gradually to
a very slender process less than 1 mm in depth, for
what must have been an extremely weak (or flexible)
junction with the jugal. Anteriorly, the maxilla is
more robust, indicating a more extensive — and pre-
sumably stronger articulation with the premaxilla.
The tapered anterior process of the maxilla, like the
posterior maxillary process of the premaxilla, seems to
have lacked teeth, although neither maxilla is well
enough preserved to establish the absence of alveoli.
However, it does appear that the upper diastema
extended several mm behind the premaxillary-maxil-
lary suture. The entire lower external surface, like
that of the premaxilla, is free of foramina.

A thin sheet of bone extends upward from the pre-
maxillary process, apparently forming most or all of
the inferior-posterior margin of the external naris,
although this region is not clearly preserved here. A
small, triangular subsidiary antorbital fenestra is
partly preserved here, separated by a robust vertical
bony bar from the large sub-triangular antorbital
fenestra behind.

The dentition extends over approximately two
thirds of the maxilla length, reaching to a position just
behind the main antorbital fenestra. The left maxilla
still bears 6 teeth, plus 9 or 10 empty alveoli or tooth
imprints. The right maxilla contains 5 teeth in situ,
plus 6 clear tooth impressions or empty alveoli and
5 possible alveoli. Accordingly, the maxillary tooth
count appears to have been 15, and possibly 16. The
anterior extremity of the left maxilla shows several
small triangular bony plates between some of the
empty alveoli: these are interpreted as inter-dental
plates.

Nasal: The nasal bones are represented by
several thin fragments and a long impression. The
precise shape cannot be determined from these, but the
paired nasals appear to have formed a straight, rather

broad and perhaps wedge-shaped, smooth-surfaced
plate of bone extending between the premaxillae and
the frontals. The contact with the frontals appears to
have been squamous. The nasal contribution to the
narial posterior border is not known, but it appears to
have been small.

Frontal: Muc of the dorsal surface of the
frontals is well-exposed, these bones having been
rotated to lie almost parallel with the bedding plane.
This permits an accurate measure of inter-orbital skull
width (9.1 mm, minimum). It also shows that the
frontals were firmly united, but not fused, along a
very straight sagittal suture. The frontal plate is
almost flat with only slight longitudinal convexities on
either side of the midline, and of moderate thickness,
as is shown along the posterior broken edge. The
articulation with the parietals is not certain.

One interesting feature of the frontals is the pre-
sence of a short forward projection along the lateral
margin, forming a unique feature of the superior
orbital margin. It is faintly reminiscent of a pal-
pebral or supra-orbital bone, but it projects forward
rather than backward, and seems to be in contact
with the main body of the frontal. It is well preser-
ved on the right side, but is largely broken away on
the left side. On both sides, it seems to have been con-
tinuous with the post-orbital, and may have been an
anterior expansion of that element into the supra-
orbital region. No comparable feature is known to
me in other theropods.

Parietal: The parietals are represented by
crushed, thin sheets of bone Iying behind the frontals
on both sides of the midline, and extensive impressions
of their internal surfaces. The latter indicate that the
sagittal suture persisted into the parietal area. Al-
though not certified as such, the fronto-parietal union
appears to have been positioned just behind the orbit.
A slightly raised narrow ridge extends transversely in
an irregular line across the large convex fragment of
the left side that lies just behind the orbit. This ap-
pears to extend from a bone that I have interpreted as
the left post-orbital. A corresponding linear feature
shows faintly in the matrix impression of the internal
surface of the right fronto-parietal. If these indeed
are the fronto-parietal suture, it seems to reflect a
very firm, solid union of these bones, a condition that
is substantiated by the fact that they are preserved
together with no apparent displacement and little dis-
tortion. That is in contrast to the disarticulated and
displaced occurrence of most other cranial elements.

Lachrymal: Both lachrymals are preserved
close to their natural positions, but both are damaged
sufficiently to preclude full description. The lachry-
mal appears to have been I-shaped, with a stout verti-
cal shaft forming a narrow pre-orbital bar between
the orbit and the antorbital fenestra. The upper and

lower extremities seem to have been expanded, prob-
ably for firm union with the maxilla (and jugal?) and
the nasal-frontal complex. Some or most of the
upper expansion may have been composed of the pre-
frontal, but this cannot be established. There is a dis-
tinct sutural facet on the inferior anterior edge of the
left frontal, which I interpret as the articular facet for
the pre-frontal.

Postorbital: This bone is easily recognized by
its T-shape. Only the left has been identified here,
forming the posterior margin of the orbit, slightly
separated from the fronto-parietal. It appears to be
a relatively thin sheet of bone with wedge-shaped
anterior (frontal) and posterior (squamosal) processes
above. The inferior process tapers gradually to an
indeterminate articulation with the jugal.

Jugal and Quadratojugal: Neither of
these bones has been identified with certainty, and
apparently are lost, concealed beneath other bones, or
so damaged as to be unrecognizable.

Squamosal: Inall probability, the fragments
overlying the postero-lateral region of the left parie-
tal, represent what remains of the left squamosal.
That is far from certain, though, as these fragments
are so severely damaged that no details are discernible.

Quadrate: At the rear of the skull is a thin
vertical lamina of bone which I interpret as the poste-
rior part of the internal half of the left quadrate. The
external half is missing. The upper extremity of this
lamina ends in a broken surface and the lower part is
concealed by the adjacent left pterygoid. If correctly
identified, this portion of the quadrate is surprisingly
slender and delicate, but the external part of the
quadrate shaft must have been much more robust.
Situated in the anterior part of the left orbit is an
L-shaped fragment which may be part of this missing
half of the quadrate, and perhaps part of the quad-
ratojugal. The “ascending” shaft of this L-shaped
fragment is quite stout and appears to have been either
L, or C-shaped in cross section. The lower part is
overlapped by a very thin sheet of bone (with broken
edges), which may be the left quadratojugal.

Pterygoid: The left pterygoid is conspicuous
below the orbital and temporal regions, extending,
forward from the quadrate to pass beneath the left
dentary. The distinctive feature is the deeply concave
cotylus of the basipterygoid articulation. Forward of
this, the palatine ramus is straight and quite narrow,
with a broadly convex ventral surface. Further
anteriorly, this appears to expand in a broad, slightly
concave bony sheet, but the lateral margin is not pre-
served. The medial margin is intact, though, showing
that an interpterygoidal vacuity existed over most or
all of the length of the pterygoids. Behind the ba-
sipterygoid articulation, the quadrate ramus extended

postero-laterally as a relatively high thin lamina at an
angle of about 30 degrees to the palatine ramus.
Unfortunately, the posterior extremity is missing.

The right pterygoid is not identifiable with certain-
ty, but the several fragments in front of the quadrate-
quadratojugal fragment, and in the orbit itself,
probably represent remains of that element.

Ectopterygoid: Not recognized.

Epipterygoid: This element has rarely been
reported in theropods, and its presence in Compso-
gnathus is open to serious question. It is mentioned
here only because one small bone closely associated
with the skull and braincase, resembles the epiptery-
goids reported by Madsen (1976) in Allosaurus. It
must be emphasized that this is an extremely tenuous
identification. The bone in question is preserved
between the cervicals and the left quadrate, just above
the braincase. The preserved portion flares slightly to
a gently convex oval surface which apparently was an
articular surface. The opposite end, preserved as
impression in the matrix, flares into a broad (thin ?)
sheet of bone which terminates in a nearly straight
edge. If this is indeed an epipterygoid, the latter must
be the pterygoid process and the oval articular surface
is for articulation with the laterosphenoid.

Palatine: Indeterminate.
Vomer: Not recognized, with certainty.

Braincase: The braincase is situated between
the dermal skull on one side and the anterior cervical
vertebrae on the other, completely separated from
both. This peculiar circumstance has been noted by
others, especially by Nopcsa (1903). It suggests a
possible violent severing of the head from the neck,
except for the fact that all components are preserved
very close together.

Certain features of the braincase are clearly recog-
nizable, but in other places ıt has been severely dam-
aged and some bones are missing. Thus, the endocra-
nium is not easily or fully interpreted. In addition,
those regions that are recognizable, for the most part
do not correspond closely with those of other thero-
pods. Again, it is difficult to establish whether these
differences are real, or due to damage and missing
parts. (See Plate 9:1.)

In general, the endocranium is widely triangular in
its ventral aspect, very broad behind at the occiput
and tapering abruptly forward. The original width
across the paraoccipital processes exceeded 16 mm and
the basioccipital-basisphenoid length is about the
same. Total preserved length of the basioccipital-
basisphenoid-parasphenoid complex is 24.5 mm.
Aside from the broad triangular form, the other dis-
tinctive aspect of this braincase is the nearly perpen-
dicular relation between the ventral surfaces and the
occiput.

The occipital condyle and the foramen magnum are
the most obvious features. The condyle, however, is
distinctly not theropod-like, being kidney-shaped
rather than nearly spherical. The transverse width of
the condyle is more than twice the sagittal dimension.
Sutures clearly show that the lateral portions are
formed of the exoccipitals, but the largest part is
basioccipital. The exoccipitals do not meet in the
mid-line, thus the basioccipital forms the ventral floor
of the foramen magnum, as usual. The original shape
and size of the foramen magnum are uncertain because
of possible crushing and broken bone edges adjacent
to the foramen, but it appears that it was much larger
than the condyle, and perhaps oval in shape, with the
transverse dimension the larger. If correct, these also
are not typical of theropods, where the foramen is
usually nearly circular and much smaller than the con-
dyle. The dorsal margin of the foramen is formed by
a smooth, transversely convex, sheet of bone that must
be the supraoccipital. The upper part is concealed in
matrix, but the height of this bone above the foramen
magnum is at least 5 mm, which indicates that the
foramen and condyle were positioned quite low on the
occipital surface. The supraoccipital is oriented al-
most perpendicular to the basioccipital — basis-
phenoid surface.

Lateral to the condyle, several fragments of bone
represent portions of the paraoccipital processes. No
suture is evident separating the exoccipital and
opisthotic. Although Nopcsa (1903) described this
region as pierced by many foramina, as in birds, it is
so fractured and damaged that only one doubtful
foramen can now be recognized. I agree with
Nopcsa, however, that this region is bird-like in its
position and orientation. It lies almost entirely in the
plane of the basioccipital-basisphenoid complex,
although there is a dorsal expansion of unknown di-
mension more or less in the plane of the foramen mag-
num.

Anterior to the condyle, much of the basioccipital
and basisphenoid have been lost, leaving only impres-
sions of their internal surfaces. The impression shows
that the floor of the endocranial cavity, at least in the
region of the basioccipital, was traversed by a low
sagittal ridge extending forward from the foramen
magnum. A similar feature is present in some birds,
but I am not aware of such a feature in other thero-
pods, or in reptiles in general. In fact, very often
there is a slight mid-line groove in the basioccipital
and basisphenoid, which marks the position of the
basal artery.

Anterior to this region are paired, but no longer
symmetrical, lateral flanges that appear to have been
crushed down onto the ventral surface of the brain-
case. These are quite prominent and apparently pro-
jected well below the endocranium. The most likely

interpretation of these structures is basipterygoid pro-
cess of the basisphenoid. Nopcsa (1903), interpreted
much smaller lateral projections further forward as
the “pterygoid apophyses”, but their position at the
posterior end of the cultriform process of the pa-
rasphenoid, makes that interpretation unlikely.

Nopcsa (1903) puzzled over the paired, near-verti-
cal longitudinal laminae at the anterior extremity of
the braincase, postulating that they might be the
pterygoids, palatines or the vomer. He finally deci-
ded, with some reservations, that they were the pala-
tines. However, these laminae are unquestionably
continuous with the other ventral elements of the
braincase, and therefore cannot be any of the bones
Nopcsa considered. Because of its double condition,
Nopcsa was correct when he ruled out the presphenoid
(which is rare in reptiles anyway). But it is quite
obvious to me that these two lamina, which join in the
mid-line, form the cultriform process of the parasphe-
noid, which normally is a double structure with an
inverted V-shaped section.

Portions of the lateral wall of the braincase are
present, and have been well-prepared (undoubtedly
with great difficulty because of the narrow space
between the braincase and other nearby elements).
On the left side, there are two distinct foramina,
piercing a slightly concave bone which I interpret to
be the prootic. The larger foramen probably is the
fenestra ovalis, and immediately anterior to it, a
similar-sized foramen I take to be the trigeminal
foramen. If correctly identified, the latter foramen
must mark the approximate junction between the
prootic and the laterosphenoid, but no suture is
evident.

Mandible.

Both lower jaws are present, but disarticulated and
slightly displaced. The most distinctive aspect of the
mandible is its extremely slender form with nearly
parallel upper and lower margins. No evidence has
been recognized to indicate the presence of a coronoid
process or of an external mandibular fenestra. Since
all three of the lateral mandibular elements are nearly
complete, I conclude that this fenestra probably was
not present in Compsognathus, as is the case in Orni-
tholestes. However, the matter is beyond proof.

Dentary: The dentary is long and surprisingly
slender, with nearly parallel upper and lower margins.
It deepens slightly toward the rear. Externally, it
appears to have been slightly convex dorso-ventrally.
In its anterior part, the external surface is pierced by a
large number of very fine pores, many of which are
arranged in two parallel rows, an upper row just
beneath the alveolar margin and a lower row close to
the inferior margin. Other foramina are scattered in
between. The upper foramına do not seem to coincide

with tooth alveoli, either in number or position. The
medial surface of the right dentary reveals a deep and
very prominent Meckelian canal, bordered above and
below by stout ridges. Much or all of this canal pre-
sumably was covered by the splenial, but there are no
distinct articular scars for this bone, except posteriorly
near the end of the dentary. Thus, it is possible that
the Meckelian canal was open anteriorly. The sym-
physis is quite short, and appears to have formed a
relatively loose or flexible union between the two
mandibles. Tiny interdental plates are present be-
tween alveoli along the entire inner side of the tooth
row. These occur as separate wedges of bone at each
interalveolar position.

The tooth row, as measured on the left dentary, is
quite long (26.2 mm), perhaps slightly longer than the
maxillary row. There are 11 teeth preserved in place
(or slightly dislocated) in the left dentary and seven
empty alveoli. The right dentary has 16 empty
sockets, plus two anterior teeth in place. Thus, the
dentary tooth count is 18, which is one of the higher
counts among theropods, exceeded only by that of
Coelophysis (25) among theropod taxa known to me.

Splenial: These elements are questionably
identified here (see Fig. 1), largely on the basis of their
location and shape. They are preserved as thin sheets
of bone or impressions which indicate a rather long
and narrowly tapered bone. The shape and dimen-
sions correspond approximately with those of the
posterior part of the Meckelian canal. Both elements
are located close to the dentaries — apparently lying
in between them. One (the left ?) overlies the upper
ramus of the left maxilla and the other (the right ?)
seems to lie beneath that maxilla.

Surangular: Both surangulars are easily
recognized lying side by side next to the left maxilla.
Both bones show the external surface, the right sur-
angular having been turned over. The surangular
foramen is evident in both. Also clearly preserved in
the right surangular is the articular cotylus for the
distal end of the quadrate. The position of this
cotylus clearly establishes that the retroarticular pro-
cess was quite long (more than 5 mm) and the arti-
cular may have extended beyond the surangular
extremity.

The external surface appears to have been almost
planar. Dorsally, a stout angulation separates the
lateral and dorsal surfaces, as in most other theropods,
so they are oriented nearly perpendicular to each
other. A faint antero-posterior ridge parallels the
lower margin, marking the upper boundary of the
articulation surface for the angular.

Angular: The left angular, incomplete, lies
immediately adjacent and parallel to the left surang-
ular, only slightly removed from its articulation with

that bone. Most of the lateral lamella is missing, but
part of its original shape can be determined from the
articulation scar on the surangular. Extending back
from this is a very slender, slightly tapered process
which articulated with the lower edge of the surang-
ular all the way to its posterior extremity. Thus the
retroarticular process was constructed of at least three
elements, the surangular and angular in addition to
the articular. The right angular possibly is represen-
ted by two fragmentary sheets of bone that overlie the
right surangular, but no distinctive features are preser-
ved. The form of the anterior end of the angular is
not known, but presumably it overlapped the posteri-
or end of the dentary in a sgquamous articulation.

Prearticular: Not recognized.

Articular?: Two sub-rectangular bones, which
at first glance look like dermal scutes, lie one to two
cm away from the two surangulars. Their identity
cannot be verified, but I believe them to be the two
articulars. My belief stems from their preserved loca-
tion close to the surangulars, their size and shape, and
the fact that there are two of them and they are
paired. Although they seem to have slightly different
shapes, perhaps due to differential crushing and
somewhat different positions in the matrix, the ex-
posed surfaces clearly are mirror images of each other.
If my identification is correct, the exposed surface is
the surangular or external surface. Each bone shows
a prominent ridge which bifurcates into two lesser
ridges at one end. This feature divides the exposed
surface into two unequal areas, the larger of which I
interpret as the articular surface for the surangular.
The smaller surface is probably for the posterior pro-
cess of the angular (see Plate 10:3).

Dentition.

Stromer (1934), presented a detailed description of
the dentition of Compsognathus, together with a sum-
mary comparison with the teeth of selected other
theropods. There is little that can be added to
Stromer’s study and what follows here is in part
taken from his work, in order that this study of
Compsognathus be complete.

As noted elsewhere in this report, the tooth count

for Compsognathus is 3 +15 or 16, Stromer (1934)

18
leer

gave it as ‚ but it looks to me as though

there might have been 16 tooth positions in the maxil-
la. Upper and lower teeth are quite similar at equi-
valent positions in the tooth rows, but there is gra-
dational change in tooth morphology and size along
the tooth rows.

The premaxillary teeth, and the anterior teeth in the
dentary, are long and slender, tapering gradually to
sharp points. The lower two thirds of the crown is
straight, but the tip is bent sharply backward at an

angle of 30 to 40 degrees. The crown is nearly circu-
lar or slightly oval in section, with the transverse dia-
meter slightly greater than the longitudinal dimension.
The crown is completely devoid of serrations or cari-
na. The first premaxillary tooth appears to have been
slightly procumbent, but probably not as sharply as
Stromer (1934) illustrated.

The first two or three dentary teeth (Plate 9:2) are
almost exactly the same as the premaxillary teeth,
both insize and shape, and the first is slightly procum-
bentlike its counterpart above. The nextthree or four
teeth are similar, but instead of the sharply bent tip,
the entire crown curves backward in a continuous curve.
These teeth also lack a serrated edge, but where the
forward-most dentary teeth are slightly compressed in
their anterior and posterior surfaces, these are slightly
compressed latero-medially, so that the greatest
crown diameter is longitudinal. There is slight varia-
tion in size among these teeth as well. "The remaining
posterior dentary teeth become progressively smaller
(shorter) and more compressed transversely, toward
the rear of the tooth row. These posterior dentary
teeth also become progressively less curved toward the
back, becoming more nearly triangular in lateral pro-
file, the rear edge being almost straight and perpendi-
cular to the dentary with the anterior surface curving,
gently back to meet it at the apex.

With only a few maxillary teeth well preserved, it
is difficult to reconstruct the complete nature of the up-
per dentition. However, those that are present seem
to parallel the posterior dentary teeth in form and
size, becoming progressively shorter and less curved
toward the back. And like their dentary counter-
parts, they are also laterally compressed and oval in
section, with short serrated posterior carinae.

It is not possible to say very much about tooth
replacement because so many teeth are missing. There
are at least eight loose teeth scattered around the jaw
elements, and numerous impressions of now missing
teeth occur along all tooth rows. The left dentary
perhaps gives the best evidence of the replacement
pattern. Eleven teeth are present, six of which are
crowded together in the anterior -most region (7 mm).
The remaining five teeth are somewhat irregularly
spaced over the next 18 mm of the tooth row. No
indisputable tooth impressions are present at the now
empty alveoli of the left dentary, so the existing
eleven teeth still in situ represent the minimum number
of functional dentary teeth when this specimen was
buried. There could have been more. The overall
distribution of these eleven remaining teeth is as fol-
OWL: UK KIK II RO OK OX EOXEOXOX
(where “O” is an empty socket and “X” a tooth in
place). As we might have expected, this pattern
suggests tooth replacement at alternating positions.

Hyoid Apparatus.

Hyoid elements have been recovered in a number of
dinosaurs, but in most instances these have been orni-
thischians. Marsh (1896) and Gilmore (1920), repor-
ted the presence of possible ossified hyoid bones in
Ceratosaurus nasicornus (U. S. N. M. No. 4735), and
I recall seeing what appeared to me to be possible
hyoid elements in some of the American Museum spe-
cimens of Coelophysis longicollis. With these excep-
tions, the hyoid apparatus appears to be unknown in
theropods. For that reason, the identification of pos-
sible hyoid bones in Compsognathus must be con-
sidered as very tentative. But the two bones in
question do not fit any other alternative skull element.

In so far as can be seen from their shapes, size and
lengths, they are the same, and thus appear to have
been paired. Both are very long, slender and straight
bones nearly 30 mm long. One is located between the
right dentary and maxilla, extending parallel to those
two tooth rows. Imprints of maxillary teeth are
pressed into it, indicating that it lies beneath (external
to) the maxilla. The second one overlaps (lies exter-
nal to) the left maxilla at a slight angle to its tooth
row. Both of these objects are parallel-edged, flat
ribbon-like bones, as preserved, but they may have
been rod-like and only flattened after burial by sedi-
ment compaction. I doubt this, though, because simi-
lar-sized ribs in this specimen do not show a compara-
ble degree of flattening. The fact that both bones
seem to lie external to the maxillae is troublesome,
since the hyoid apparatus in life is situated between
the mandibles, and thus lies inside, or medial to, the
maxillae. How they both could have been displa-
ced to lie outside of the maxillae, is the critical que-
stion against their being hyoid elements. But, in view
of the disarticulation and dislocation of many other
skull elements, that identification is not precluded, and
on morphological grounds it seems most probably cor-
rect.

AxıialSkeleton
Vertebral Column.

The vertebral column is complete, except for an
unknown number of caudals distal to the fifteenth,
and two segments in the dorso-sacral region that are
represented only by impressions. 'The pre-sacral count
totals 23, and the pre-sacral length approximates
23.6 cm, of which less than half (10.5 cm) is cervical
length. There are 10 cervicals, 13 dorsals, 4 sacrals
and more than 15 (probably more than 30) caudals.

Cervical vertebrae: The cervical series
consists of 10 segments, including the atlas, and is com-
plete, although not all of the atlas has been recog-
nized. Von Huene (1908) reported 12 cervicals and
11 dorsals, without giving any detailed explanation,
but later (1925) he specified 10 cervicals and 13 dor-

sals?). As noted previously, the neck is highly arched
backward, with the atlas and skull separated from the
cervicals. Only the intercentrum of the atlas has been
(questionably) recognized here, together with two thin
fragments that I suspect might be the atlas neurapo-
physes, (see Fig. 1). No sign of the odontoid has
been detected. The atlas intercentrum is situated in
the area between the skull, braincase and anterior
cervicals, with its posterior and ventral surfaces ex-
posed. The posterior surface is gently convex trans-
versely, and strongly convex dorso-ventrally. The
ventral is also convex transversely, but
slightly concave longitudinally. Its upper part is con-
cealed by a thin triangular sheet of bone (the right
atlas neurapophysis ?), so that part of the intercen-
trum cannot be determined, but presumably it was
strongly concave so as to fit beneath the odontoid.
The transverse width of the intercentrum (4.45 mm) is
the largest dimension and is close to that of the occipi-
tal condyle (4.6 mm). Little can be said about the
questionable neurapophyseal fragments, except that
they are very thin, concavo-convex, triangular sheets
of bone with original lengths of something more than
10 mm.

surface

The axis is situated just to the left of the braincase
and slightly removed from the third cervical. I am
not certain, but there appears to be a very thin axis
intercentrum fused to its anterior end. The axis cen-
trum is distinctly shorter than those of succeeding
cervicals, but like all the following cervicals, it is
marked by a conspicuous small oval pleurocoel in its
anterior lateral surface. The axis centrum also is
slightly opisthocoelous. The neural arch is damaged,
but appears to have been long and of moderate height.

Although the quality of preservation varies from
one segment to another, the remaining eight cervicals
appear to have been quite similar to each other. The
centra incerease in length to a maximum of 12.7 mm
for the sixth and seventh segments, then length di-
minishes progressively to 10.9 mm for the ninth and
tenth. All cervicals are strongly opisthocoelous and
centra are narrow-waisted with laterally facing,
anteriorly placed pleurocoels. The neural arches are
all severely damaged and difficult to interpret, but
they appear to have been relatively low, long and
massive, with stout zygapophyses.. No diapophyses
could be identified, although the double-headed design
of the cervical ribs clearly establishes their original
existence. Similarly, no cervical neural spines have
been recognized.

Dorsal vertebrae: In many instances, it is
difficult to select a distinctive point of separation
between the cervical and dorsal vertebrae, and in most
cases it is decided on the basis of arbitrary features.

3) Von Huene’s thirteenth dorsal, in fact, turns out to be
the twelfth, a point that is discussed later.

The present specimen is no exception. I selected the
point between the tenth and eleventh presacrals as the
most appropriate place because there is a distinct change
in the morphology of the ribs here and, although the
preservation does not permit an absolute statement,
there appears to be a change in vertebral morphology
here as well. Although badly crushed and fractured,
the eleventh presacral is much shorter (9.9 mm) than
the tenth (10.9 mm). Also, the eleventh presacral
seems to be the first in the series that lacks pleurocoels,
although the crushed state of the centrum does not
allow an unqualified statement on this. Most of the
succeeding presacrals clearly are without pleurocoels.
Finally, the rib (impression) adjacent to the eleventh
presacral is more robust, although not much longer,
than the preceeding cervical ribs and bears a well-
defined, long-shafted capitular process like those of
the succeeding thoracic ribs.. On these criteria, there
are 13 dorsal vertebrae, the last two of which are
indicated only by impressions.

The second dorsal vertebra has a length of 9.4 mm,
slightly shorter than the first, perhaps the result of
distortion, whereas the rest have lengths very close to
10 mm. The centra appear to have been elongated,
slightly narrow-waisted, spool-shaped structures.
They are either amphiplatyan or slightly platycoelous.
Because of the crushed state of many vertebrae, and
the superimposed dorsal ribs, no sign of parapophyses
or facets for the capituli are discernible. Even more
surprising, in view of the widely separated capitulum
and tuberculum of the dorsal ribs, is the apparent ab-
sence of prominent transverse processes.

The neural arches are all long and low, with stout
zygapophyses. The neural spines also are low, rising
less than 3 mm above the arches, but long — ranging
from 7 to 9 mm in longitudinal dimension. These
spines are situated at the rear of each segment, and in
most instances overhang the anterior part of the suc-
ceeding vertebra. Anterior neural spines are nearly
rectangular in shape, but posteriorly they become
somewhat fan-shaped. All the dorsal spines have
slightly thickened anterior margins (suggestive of well-
developed interspinous ligaments), as well as lateral
surfaces with distinctly sculptured texture. The latter
may reflect muscular attachment, presumably slips of
the M. lattisimus dorsi.

The zygapophyses are short, but stout and situated
well above the centra. The postzygapophyses are
positioned directly below the posterior margin of the
neural spine, whereas the prezygapophyses project far
forward of the neural spine. Because all zygapophy-
ses are poorly preserved but still in close articulation,
it is not possible to determine the attitude of the arti-
cular facets. Most probably, though, they were
slightly inclined toward the mid-line.

A curious and inexplicable problem exists concer-

ning Huene’s (1925 & 1926) tally of the dorsal
vertebrae. After concluding that there were ten cer-
vical vertebrae, he then noted that these are followed
by 12 dorsal vertebrae in front of the ilium and the
neural process of the 13th is still to be seen above the
anterior tip of the ilium. He then stated that five
sacral vertebrae must follow this last. In other words,
according to von Huene, the “neural process above
the tip of the ilium” is the 23rd presacral segment,
including an undetected atlas.. According to my
count, that same neural spine is the 22nd presacral
vertebra. I count the impression behind that “neural
spine above the tip of the ilium” as the 13th dorsal,
largely on the grounds that it (like its predecessor) is
missing, and not preserved co-ossified with the sacrals
behind. This last segment, von Huene obviously
counted as one of his “five” sacrals, but that in no
way explains how he counted 23 segments in front of
this segment.

The relatively long and slender centra of the dorsal
vertebrae, and the fan-shaped neural spines are unique
among theropods, although a variety of “coeluro-
saurs” (i. e., Coelophysis, Aristosuchus, Coelurus, and
to a lesser extent, ornithomimids) have moderately
elongated dorsal vertebrae.

Sacral vertebrae: The sacrum, unfortu-
nately, is entirely obscured by solution, overlying por-
tions of the ilium and femur, and growth of secondary
calcite crystals. Consequently, nothing can be said
about the morphology of the sacrum, or the sacral
number with absolute certainty. However, using the
lengths of the last dorsal, of about 12 mm (for the
thirteenth dorsal by my count) and the first complete
caudal preserved (the second caudal by my interpreta-
tion) of 11 mm, as indices, the sacrum probably con-
sisted of only four segments, rather than five as von
Huene (1908, 1925, 1926, 1932) and subsequent
authors have cited. Unless the sacral segments of
Compsognathus were much shorter than adjacent ver-
tebrae in front and behind, the space available
(41 mm) in this specimen simply is too short to have
Yet, I cannot prove
that the sacral number was four rather than five. Two
vertebrae are missing (although preserved poorly as
impressions) at the dorsal — sacral “junction”, as
was noted above. Their absence suggests that they
were not co-ossified with the segments behind, and
therefore are best considered as the 12th and 13th
dorsals. Two co-ossified centra are partly visible
behind the acetabulum. These are interpreted here as
the 3rd and 4th sacrals (on the dimensional grounds
listed above). The next vertebra behind is displaced,
turned almost 90 degrees to the sacral and caudal
series, and thus clearly not co-ossified with the sa-
crum. I assume this to be the first of the caudal verte-
brae.

contained five sacral vertebrae.

Caudal vertebrae: The caudal series is rep-
resented by 16 segments, the last seven of which are
only impressions. The centra of the proximal caudals
are strikingly similar to the dorsal centra; long, slen-
der, slightly narrow-waisted, spool-shaped elements.
There are no pleurocoels, and no transverse processes
— not even on the most anterior segments. This last
feature, is amost unusual condition, and raises questions
about the organization of the tail musculature and the
function of the tail. It is not certain, but the preser-
ved centra all appear to be amphiplatyan. The centra
become progressively longer distally, with the last pre-
served vertebra (the tenth), the longest. This suggests
a very long tail.

All neural arches have been destroyed by a large
fracture which follows the course of the caudal series.
The neural spines on the first few caudals are taller
and narrower (shorter in the anterior-posterior
dimension) than those of the dorsal vertebrae, but still
are fan-shaped and erect. At the seventh caudal, the
neural spine is inclined slightly backward, and suc-
ceeding spines slope progressively further backward
and are successively shorter until at the tenth caudal
only a low nubbin remains.

Chevrons: Chevrons are present throughout
the preserved portion of the caudal series. The first
is preserved in place between the second and third
caudals. All are similar in form and size, with very
little apparent progressive diminution distally. They
are slender, parallel-edged and slightly curved bones
that taper only very slightly toward their extremities.
The fact that the most distal chevron preserved (the
tenth) is not much shorter than the first, suggests that
the tail was unusually long and that the preserved part
represents only a small fraction — perhaps less than
a third — of the original tail length. This is sup-
ported by the relative sizes and lengths of the last
preserved caudals and the proximal elements. On the
other hand, the complete absence of transverse pro-
cesses on the caudals could be interpreted as evidence
of a relatively short tail, but I consider that unlikely.

Dorsal Ribs.

Cervicalriıbs: A totalof 14 cervical ribs can
be identified about the slab. Four of these clearly are
paired and situated adjacent to the ventral surfaces of
the fifth and sixth cervical vertebrae, presumably
close to their natural positions. These seem best inter-
preted as the ribs of the fourth and fifth cervicals, in
view of the fact that there are no ribs closely associa-
ted with the next five vertebrae and there are ten
similar ribs scattered about in the area of the neck (see
Fig. 1). From this scattered occurrence, it is obvious
that the cervical ribs were free. All cervical ribs
feature broad, triangular proximal portions with
widely separated capitular and tubercular heads.

Posteriorly, they taper abruptly into long (up to
30 mm or more), hair-like filaments (diameter,
0.2 mm or less). The anterior-most ribs are less deli-
cate and are straight, whereas those that are scattered
about (and have been attributed to the posterior cer-
vical segments) are very delicate and distinctly cur-
ved. Presumably, this curvature reflects a degree of
“permanent” natural curvature of that part of the

neck.

Thoracic rıibs: One or both members of
eleven pairs of thoracic ribs are discernible, either as
fragments of bone, or as impressions. In most instan-
ces, only the proximal third or half is present, the
distal portions having been broken away or obscured
by crystal masses in the lower regions of the body
cavity. A few fragments of distal portions (fourth
and fifth ribs of the left side) indicate the approximate
complete length of some. All were double headed,
with the tuberculum and capitulum widely separated,
the latter at the end of a long narrow process. The
rib shafts are slightly curved, tapering abruptly proxi-
mally to a nearly uniform thickness over half or two
thirds of rib length. The distal third tapers very
slightly. "The shafts appear to have been oval in cross
section and perhaps hollow, since nearly all preserved
ribs have collapsed due to compaction into a figure 8
cross section.

Gastralia.

A number of small rod-like bones adjacent to the
humerus represent part of the gastralia cuirasse, and
marks the position of the ventral surface of the body.
Additional displaced gastralia are scattered close to
the knee. These last suggest that the ventral body
wall ruptured, perhaps due to decomposition gases
built up within the body cavity. Further evidence of
that is the isolated tiny lower jaw preserved together
with these displaced gastralia elements, that presuma-
bly belongs to the small skeleton within the body
cavity of Compsognathus. None of these elements
are complete, so original shapes and lengths are inde-
terminate. Some of them are more than 15 mm long,
most are cylindrical or slightly compressed and nearly
all are curved, either uniformly or variably. Most
elements seem not to have been symmetrical, sug-
gesting that most were lateral (but not necessarily
paired) components of a two (or three) rowed struc-
ture, perhaps similar to the arrangement illustrated by
Lambe (1917) and Gilmore (1920). A few fragments
look as though they might have been symmetrical, and
thus components of a median row of gastralia. The
ventral body wall region has been disturbed by solu-
tion and crystal growth, so it is not possible to recon-
struct accurately the original arrangement or dimen-
sions of the gastralia cuirasse. It is presumed to have
extended from near the sternal region close to the
pectoral girdle back close to the distal extremity of

the pubis, but there seem to be far too few elements
preserved here to form such a long structure. The
gastralia close to the humerus seem to be little dis-
turbed, showing that this region was sheathed ventral-
ly by these dermal bones. The displaced gastralia
back close to the pubis suggest, but certainly do not
prove, that they may have extended this far back.

Appendicular Skeleton:
Pectoral Girdle and Forelimb

Both forelimbs and the pectoral girdle are incom-
pletely represented by impressions and partial or com-
plete elements. Despite being incomplete, most of the
important features are discernible. In contrast to the
hindlimb, the forelimb total length is quite short, little
more than one third (approximately .37) the hindlimb
length, unusually short for a “coelurosaur”. The
forelimb is moderately robust, though.

Pectoral girdle.

As with the pelvis, portions of the pectoral girdle
are completely missing or concealed and other parts
are represented only by impressions. Only the upper
portions of the scapulae and the anterior margins of
the coracoids are preserved. Consequently, the mor-
phology of the complete shoulder girdle cannot be
reconstructed.

Scapula: The scapular blade was a very thin,
narrow sheet of bone slightly expanded at its dorsal
extremity. In the lower part, the blade was some-
what thicker and parallel-edged. An impression of
the lower part of the right scapula shows a distinct
convex dorsal margin which, from its shape and loca-
tion, is interpreted here as the acromion. If that is
correct, Compsognathus possessed an unusually large
acromion for a theropod. Presumably, this reflects
the one time existence of relatively large deltoideus
musculature, which would correlate with the robust
construction of the forelimb.

Coracoid: Situated at the upper end of the
humerus, and lying beneath it, are two very thin,
sheet-like fragments of bone. The anterior margins of
both are alike and uniformly convex. The margin of
the underlying right fragment appears to be con-
tinuous with a curved impression margin that extends
dorsally and meets the anterior extremity of the
acromion mentioned above. This junction presumably
marks the position of the coracoid — scapula suture,
as in most theropods. Unfortunately, nothing can be
determined about the posterior or lateral portions of
the coracoid, but what is preserved indicates a rela-
tively large semi-circular anterior portion. The
glenoid is completely unknown.

Forelimb.

Humerus: Only the left humerus is present, the
right being represented only by an incomplete impres-

sion. Unfortunately, the proximal 10 to 20 per cent
of the humerus is missing, so no information is availa-
ble about the nature of the proximal articulation, the
deltopectoral crest, or humeral length. I estimate the
original length to have been 38 to 40 mm, but it
might have been as great as 45 mm. Von Huene
(1932) estimated a maximum length of 52 mm, but
that seems excessive. In non-tyrannosaurid thero-
pods, the radius ranges from two thirds to three
fourths of humeral length. On the basis of the radius
length in Compsognathus (24.7 mm), the humerus
should have been between 32.8 and 36.9 mm long.
I suspect it may have been slightly longer. The shaft
was hollow (it is now crushed almost flat), straight
and probably nearly cylindrical. No details per-
taining to the distal condyles, which face down into
the matrix, can be determined, but the preserved con-
formation of the crushed posterior surface suggests
that the radial condyle (as usual) was larger than the
ulnar condyle.. Contrary to von Huene’s (1925)
remark that the processus lateralis extends two thirds
of the length of the humerus), the deltopectoral crest
seems to have been quite short. Its preserved length is
less than 8 mm (out of a preserved humeral length of
33 mm). This is relatively short compared with other
theropods where the deltopectoral crest usually
approximates one third of humeral length (much less
in ornithomimids), but in no instance that Iam aware
of, does it reach two thirds. However, in the absence
of the proximal end of the humerus, it is quite possible
that the deltopectoral crest of Compsognathus was of
normal proportions.

Radius and Ulna: The radius and ulna are
straight, slender bones with slightly expanded proxi-
mal and distal extremities — especially the proximal
end of the ulna which bears a prominent olecranon.
Both bones were hollow and seem to have been nearly
circular in cross section. No details of the articula-
tions can be seen. As shown in the table of dimen-
sions, the radius is significantly shorter than the ulna,
underscoring the prominence of the olecranon. In
fact, relatively speaking, I am not aware of such an
elongate olecranon in any other theropod. This must
have provided unusual leverage for the M. triceps
brachii for quick or powerful extension of the forearm,
but it is not clear what adaptive significance this
might have had.

Carpus: Curiously, the left manus is preserved
separated from the radius and ulna by a gap of more
than 6 mm, within which there is no evidence of any
carpals. At first glance, this gap might be interpreted

#) Von Huene’s statement is here attributed to the possibi-
lity that he misinterpreted the anterior portion of the right
coracoid (see Fig. 1) as the left deltopectoral crest, but this
thin sheet of bone is clearly separate from the humeral
shaft, which in fact, overlies it.

TABLE 1

Measurements (inmm) of Compsognathus longipes.

Skull length

Skull width

Skull height

Orbit length

Orbit height
Antorbital fenestra

Dentary length
Surangular length
Scapula length
Humerus length
Radius length

Ulna length

Mtc. I length

Mtc. II length

Mtc. III length
Phalanx I—1 length
Phalanx I—2 length
Phalanx II—1 length
Phalanx II—2 length
Femur length

Tibia length

Fibula length

Pubis length

Ischium length

Mtt. I length

Mtt. II length

. III length

Mtr. IV length

Mtt. V length
Phalanx I—1 length
Phalanx I—2 length
Phalanx II—1 length
Phalanx II—2 length
Phalanx II—3 length
Phalanx III—1 length
Phalanx III—2 length
Phalanx III—3 length
Phalanx III—4 length
Phalanx IV—1 length
Phalanx IV—2 length
Phalanx IV—3 length
Phalanx IV—4 length
Phalanx IV—5 length

Vertebral Number
Cervial 1— —

Cervial 2 — 8.7
Cervical 3 — 9.5
Cervical 4 — 11.0
Cervical 5 — 12.3
Cervical 6 — 12.7

70—75 est.
20 est.
30 est.
19%#est:
15 est.
11.8
Left Right
42.9
299,21, 29.8 +
38 est.
38—40 est.
24.7
28.5
17.6
13.95
1351
Vad; 7.8
9.6 97
14.5 14.45
10.4 10.4
67 est
87.7 87.6
82.1
60 est.
40 est.
9.7
48.8 ? 50.4
56.0 55.95
51.8
16.0 15:9
8.7 8.8
458
14.2 14.3
13.7 13.65
12.35
17 est. 16.9
13.65
11:5
10.2
10.5 est.
10.6
91
10.5 est.
71
Vertebrallengths
Cervical 7 — 12.7
Cervical 8 — 11.3
Cervical 9 — 10.9
Cervical 10 — 10.9
Dorsal 1— 9.9
Dorsal 2 — 94

Dorsal 3 — 9.8 est.
Dorsal 4— 9.1 est.
Dorsal 5— 9.7 est.
Dorsal 6 — 9.9
Dorsal 7 — 105
Dorsal 8 — 10.2
Dorsal 9 — 12.2 ?

Dorsal 10 — 10.75
Dorsal 11 — 11.4
Dorsal 12 — 11.5 est
Dorsal 13 — 12 est.
Total sacral length 41.1

as evidence of a cartilagenous state of the carpals, but
considering the highly ossified nature of the adjacent
elements, that seems most unlikely. The right carpal
area is concealed. It is certain that carpals were
present during life, but whether they are preserved
here and can be recognized is another matter. Three
objects are present and seem to be of proper size.
These are: first, a roughly rectangular impression
3.5 mm in maximum dimension is situated between
the impressions of the left radius and ulna; second,
there are two equal-sized and similarly shaped objects,
one close to the prominent claw at the end of the left
hand and the other, an impression, just to the right of
the right hand next to the isolated long phalanx im-
pression (see Fig. 1). The location of these three ob-
jects in the immediate vicinity of the two disartic-
ulated hands, their size and shape, and the gap at the
left wrist, all lead me to the conclusion that they are
the missing carpals.

Recognizing the uncertainty of negative evidence,
nevertheless, I suggest that the carpus of Compsogna-
thus probably consisted of only two carpals because of
the presence of only two distinct types among these
three objects, and the absence of any other obvious
carpal-like objects anywhere else on the slab. Such a
wrist condition seems unlikely in view of the carpus
construction in other theropods: four carpals in Orni-
tholestes and Coelophysis and five in Allosaurus, Gor-
gosaurus and Ornithomimus. But Deinonychus ap-
parently had only two separate carpals, and Veloci-
raptor also may have had only two wrist elements.
Not much can be said about the morphology of these
supposed carpals in Compsognathus, except that they
are more or less rectangular, and apparently were
relatively thin plates with at least one surface slightly
concave.

Manus: In his original description of Comp-
sognathus, Wagner (1861) was very careful not to
specify the number of digits in the manus, but nearly
everyone else who has since written about this unique
specimen (Marsh, 1895, 1896; Zittel, 1895, 1911,
1918; von Huene, 1932, 1956; Romer, 1956; Steel,

Sacral 4— 86
Cauddal 1— —
Caudal 2 — 10.9
Caudal 3 — 11.2
Caudal 4 — 115
Caudal 5 — 11.8
Caudll 6 — 121
Caudal 7 — 12.6
Caudal 8 — 12.9
Caudal 9 — 13.2

Caudal 10 — 13.3

1970) has specified three functional digits in the hand.
I disagree. Both hands are partly disarticulated, but
the elements are not widely scattered over the slab.
Close inspection reveals that only 14 elements are
present, including four claws of two kinds. These are
preserved either as impressions or actual bones. Fur-
ther inspection shows that there are only seven
different kinds of elements represented — each of
which is duplicated. There are no extra or unmatched
bones. In the left hand, there are three relatively long
bones, one quite robust, another slightly less robust,
anda third that is very slender. On the bases of their
location, sizes and proximal articular surfaces, these
appear to be metacarpals. They are preserved in the
proximal region in both hands. In addition, the left

IO mm

Figure 4: Reconstruction of the left hand of Compsogna-
thus longipes in dorsal aspect, according to my interpreta-
tion of the hand elements as registered in Figure 1. As ex-
plained in the text, it is highly improbable that additional
phalanges were originally present, but then lost in the spe-
cimen. The reduced formula of II (two phalanges instead
of three) is unique, clearly separating Compsognathus
from all other two-fingered theropods.

hand contains two phalanges of quite disparate
lengths and one claw very close to the longer of the
two phalanges. These same three elements of the
right hand are preserved displaced and separated to
the right of the forelimbs. Among the four claws,
only two sizes and shapes are present, as is shown in
Figure 1 and Plate 9:3 and 9:4.

I interpret the most robust metacarpal as the first,
largely because of the basal expansion on one side,
which clearly did not adjoin an adjacent metacarpal
and therefore must have been either an external or
internal surface of the metacarpus. This expansion is
quite similar to the basal internal expansion of meta-
carpal I in Deinonychus, Velociraptor, Ornitholestes,
Struthiomimus and other theropods, hence I conclude
this must be metacarpal I. 'The very slender element
is interpreted as metacarpal III, and apparently was
vestigial. That leaves the remaining element as meta-
carpal II. On the basis of their relative widths proxi-
mally, I believe the short phalanx to be the proximal
phalanx of the first digit and the long phalanx to be
the proximal phalanx of II. Because of the preserved
relation in the left hand, I interpret the longer of the
two claw types to belong to the second digit. Since
there are no unmatched extra phalanges or claws, and
it seems highly improbable that on|y corresponding
elements would be missing from both hands, I con-
clude that there could only have been two functional
digits in the hand of Compsognathus, plus a remnant
(metacarpal) of a third, non-functional digit.

Von Huene (1926) interpreted the hand elements
preserved here somewhat differently, apparently
believing that some phalanges were missing. In the
left hand, he interpreted the long phalanx as the pro-
ximal phalanx of digit I, but in the right hand, the
impression of the long phalanx, which has exactly the
same length and shaft width, he interpreted as the
second phalanx of digit II. I consider these to be the
same bone (II-1) from opposite hands. He also inter-
preted the massive broken bone adjacent to the ulna,
which has a claw impression apparently articu-
lated with it, as I-1, but its size and position adjacent
to the other metacarpals indicate it is metacarpal 1.
Von Huene’s interpretation of the hand has been in-
cluded in Figure 1, together with mine, because of the
importance of evaluating his and my reconstructions
of the hand. In my opinion, the organization of the
hand, perhaps is the most critical evidence available
for judging the proper systematic placement of Comp-
sognathus.

I recognize that there may well be several phalanges
missing, but this seems highly unlikely since all seven
kinds that are preserved are matched by a mate. If
any elements are missing, then the same bones would
have to be missing from both hands. Thus, the digital
formulae appear to have been 2—2—0, with digits IV

IOmm

Figure 5: Profile of the first and second unguals of the
hand of Compsognathus for comparison with the ungual
form of other theropods (see Fig. 77, Ostrom, 1969b). The
orientation is standard, with the chord of the articular
facet arc oriented vertically. This chord has been extended
(h = height) to meet a perpendicular (e = extension) from
the ungual extremity. The ratios of height to extension (.61
and .70) are relatively low, and the radius (r = heavy
dashed line) of ungual rotation has a low inclination similar
to that of Ornitholestes and Ornithomimus. The arrows
indicate the projected traces of the inner cutting edges of
each ungual compared with the tangents to the arcs of
ungual rotation (see Figure 6). — The upper figure shows
the bony ungual of the second digit with the outline
(dashed line) of the horny sheath (see also Plate 9:5).

and V completely lost. The position and very slender
construction of the bone that I interpret as metacarpal
III, seems to eliminate the possibility of a functional
third digit. (It is also possible that this slender me-
tacarpal is the first, rather than the third, but this
would be contrary to patterns in all other theropods.)

If my reconstruction is correct, the hand of Comp-
sognathus is unique among theropods, although it is
somewhat similar to that of Albertosaurus (Gorgosan-
rus), Tyrannosaurus and Tarbosaurus. But unlike
these larger theropods with two fingered hands, a
complete third metacarpal is present, the second digit
is shortened, and the forelimb is not so extremely

IO mm
—.
I
o°
Figure 6: Mechanics of the ungual and penultimate

phalanx of the second digit of the manus in Compsogna-
thus, showing the angular relationship of the “cutting
edge” of the bony ungual to the arc of ungual rotation.
This angle is a very large 58 degrees, which compares with
the 60 degree angle of the third ungual of Ornitholestes.
(The “cutting edge” of the horny claw would be much
smaller, and thus more efficient, as can be judged from the
upper figure of Figure 5, but since the horny claw is so
rarely preserved, I apply this technique to the bony ungual
for comparsion with other theropods.) The large “cutting
angle” in Compsognathus suggests that the hand claws
were less suited for cutting or piercing than were those of
Deinonychus, or even Allosaurus (see Fig. 78, Ostrom,
19696).

shortened in Compsognathus. In another respect, the
hand of Compsognathus resembles that of ornithomi-
mids (and Deinocheirus), with its three similar
lengthed metacarpals. In all other theropods, the first
metacarpal is much shorter than the second.

Another interesting aspect of the hand is the design
of the terminal phalanges. The claw of the second
left finger is particularly well preserved (see Plate
9:5), including parts of the horny sheath that covered
the bony ungual. The latter was about 50 per cent
longer than the supporting ungual. In my Deinony-
chus study (Ostrom, 1969 b), I utilized a number of
parameters by which claw shapes could be compared
and described. Applying these parameters to the
bony unguals of Compsognathus, reveals that they are
not strongly curved as compared with some other
theropod manual unguals. They have only a moder-
ately high ratio of height to extension and a short
height relative to the radius. This suggests to me that
the manual claws were not purely raptorial or grasp-
ing, and certainly not piercing or cutting structures.
This interpretation seems to be substantiated by the
angular relationship between the ventral “cutting”
edge of the ungual tip and a tangent to the arc
through which the ungual tip passed during flexion

against the proximal phalanx (Fig. 6). This angle is
a large 58 degrees. In all these parameters, the bony
claws of Compsognathus most closely resemble that of
digit III of Ornitholestes hermanni (A.M.N.H. 587).
Compare these features of Compsognathus (Fig. 5 and
6) with those of Figures 77 and 78 in Ostrom, 1969 b.

Appendicular Skeleton:
Pelvis and Hindlimb

Although neither one is completely preserved, the
hindlimbs are one of the most distinctive features of
Compsognathus, being very robust and surprisingly
long. With a total length of more than 27 cm, the
hindlimb is much more than twice the length of the
forelimb, and is at least 10 per cent longer than the
presacral vertebral length. Compsognathus was a
very long-legged creature. The pelvis is less complete,
but what is preserved is of typical theropod organiza-
tion.

Pelvis.

The pelvis has suffered extensive post-preservational
damage, particularly to the ilia. All elements were
originally present in natural articulation, but now
most of the left ilium is missing and only the impres-
sion of the upper border of the right ilium remains,
the shaft of the left pubis is broken away and only the
ischia are still nearly intact. "The pelvis was of normal
theropod design with the ischia projecting down and
to the rear and the pubes extending antero-ventrally.

In past years, no special attention to pubic — ischia-
dic orientations would have been considered necessary
in describing a theropod pelvis. But several recent
discoveries have changed all that. The Harvard spe-
cimen of Deinonychus (Ostrom, 1976 a) clearly shows
that in that taxon (at least), the pubes projected
downward and slightly — or perhaps sharply — back-
ward, perhaps even parallel to the ischium. Barsbold
(pers. com.) has reported that in Velociraptor the
pubes project backward parallel and immediately
adjacent to the ischia. A similar, bird-like pubic
arrangement also appears to have been present in
Oviraptor (Barsbold, pers. com.). No such ornithic
pelvic traits are evident in the Compsognathus re-
mains.

Ilium: From the fragmentary evidence pertain-
ing to the ilia, these bones appear to have been quite
long (between 5 and 6 cm)., shallow in height, and
positioned quite close to the mid-line. The impression
of the upper border of the right ilium gives the best
evidence of length and shape. It shows a nearly
straight, but gently convex upward profile, the highest
point of which occurs above the level of the sacral
neural spines. The original length of the ilium is in-
determinate, but the anterior process appears to have
been slightly longer than the posterior iliac process.
The original shapes of these processes are unknown.

Pubis: The pubes have been slightly displaced
from each other, with the left pubic shaft represented
only by an incomplete impression, and the right shaft
by several massive fragments. The incomplete proxi-
mal portion (of the left pubis) is massive in its con-
struction, presumably for robust articulation with the
ilium. Distally, the pubes narrow abruptly into
slender, oval-in-section shafts, which join each other
just above mid-length in a very narrow symphysis.
The fused, distal extremities, are expanded longitudin-
ally into the typical foot-like structure of all ther-
opods. Due to breakage, the exact size and shape of
this pubic “foot” is not determinate, but the preserved
portion of the anterior part suggests that there was
very little (if any) projection of this expansion anteri-
or to the pubic shaft, as there is in most theropods (see
Struthiomimus, Deinonychus, Tyrannosaurus, Allo-
saurus, for example).

Ischium: The two ischia are preserved together,
one overlying the other. They are the best preserved
elements of the pelvis. Compared with the long
pubes, the ischia are surprisingly short — reminiscent
of the condition in Deinonychus (Ostrom, 1976 a),
although not so extreme. The proximal region is
expanded dorsally and anteriorly for union with the
ilium and pubis. Below this, the body of the ischium
narrows markedly, with the anterior and upper mar-
gins distinctly concave. The anterior margin then
expands forward into a delicate, sharply pointed
obturator process, which is much more delicate and
sharply tapered than in any other presently known
theropod. From this process, the ischium tapers
sharply backward into a narrow cylinder with a slight
distal expansion. Because they are slightly displaced
(as preserved), the underlying right ischium clearly
reveals the symphysial suture surface extending over
the ventral ischial length from the obturator process to
the posterior extremity. The overall shape of the
ischhum — plate-like proximally and rod-like distally
— most closely resembles that of Tyrannosaurus,
differing only in the longer taper of the obturator pro-
cess, the slighter distal expansion, and of course, in
size.

Hindlimb.

Femur: Neither femur is complete, so few anato-
mical features can be reported. Fragments of the pro-
ximal end of the left femur (and the dorsal rim of the
acetabulum) mark the upper extremity and the im-
pression of the proximal end of the left tibia permit a
reasonable length estimate (75 mm) for the femur.
This estimate is corroborated by the preserved location
of the distal end of the right femur, approximately
70 mm distant from the acetabulum. The clear im-
pression of the left femur shows a rather thick, cylin-
drical shaft with slight antero-posterior curvature.
No clear imprint or other evidence of a fourth

trochanter is discernible in this impression. The splin-
tered and incomplete shaft of the right femur shows
that the femora were hollow, and nearly circular in
section. The most distinctive aspect of the femur,
though, is its surprisingly stout or robust proportions.

Tıbia: The tibia is slightly less robust, but much
longer than the femur. It too is hollow and circular in
section (as evidenced by the shaft impressions). The
proximal ends of both are missing or incomplete, so
the nature of the articular surfaces and the cnemial
crest cannot be determined. But the distal end of the
left tibia, and a good impression of that of the right,
show some of the details of the tibia-tarsal con-
struction. In contrast to the femur, the tibia is
straight-shafted.

Fibula: The right fibula has separated com-
pletely from the tibia, showing that these elements
were not fused at any point along their lengths. The
fibula is an extremely slender long bone with a
strongly concave medial shaft surface for close appo-
sition against the tibia, and an equally convex external
surface. The left tibia shaft shows a very narrow,
faintly flattened strip along its antero-external surface,
marking the area of fibular contact. Proximally, the
fibula flares into a very broad (antero-posteriorly)
head for articulation against the femur, while distally
it is only slightly enlarged into a short rounded articu-
lar surface for union with the calcaneum. The most
distincetive thing about the fibula, is its extremely
slender shaft, which is in sharp contrast to the robust

shaft of the tibia.

Tarsus: The tarsus clearly was of mesotarsal
design, but unfortunately the exact details are no
longer determinable. The distal extremity of the left
tibia is present, more or less intact, showing its exter-
nal aspect, including the extremity of the fibula next
to it and a “proximal tarsal” in natural articulation
closely appressed against the end of the tibia. The
surprising feature of this left tarsus is the large ante-
rior-posterior dimension of the “proximal tarsal”,
which is almost twice as broad as the fibular extremity.
The impression in the matrix of the external surface of
of the right tibia extremity seems to show the same
condition — a very large (antero-posteriorly) “proxi-
mal tarsal” with a strongly rounded distal profile.
The only difference here is that the right fibula is dis-
placed, thereby revealing an underlying “ledge and
shelf” articulation of this tarsal with the distal surface
of the tibia (see Fig. 1). Unfortunately the anterior
surface of the right tibia is poorly exposed, but what
can be seen does not show an ascending process of
the astragalus — this large “proximal tarsal”.

Wagner (1861) made no mention of the tarsus,
except to say that it was short, and Marsh (1895,
1896) gave no detailed description or illustration, but
Baur (1882) described and figured a fragment of the

distal end of the right tibia which he removed from
the specimen. Most unfortunately, this fragment,
apparently with tarsal elements attached, no longer
exists. 'Thus we are forced to rely on Baur’s interpre-
tations and illustrations, with no means of checking
them. Furthermore, these illustrations (1882: Figs. 42
and 43) and descriptions are not as clear as we might
like. For example, the lateral surface of Baur’s frag-
ment does not correspond with the impression left in
the matrix, nor does it match the exposed lateral
(equivalent) surface of the left tibia and tarsus, which
are still present. The large, rounded “proximal tarsal”
is not present in Baur’s illustration, nor does he show
any scar or articular facet for this element — which is
most conspicuous on the left side. But perhaps the
most important detail of Baur’s paper is his interpre-
tation of a narrow ridge-like feature that extends
along his “anterior” surface of this now-lost tibial
fragment. He identified this as the “Tibiale-aufstei-
gende Fortsatz” — the ascending process of the
astragalus. I would accept this interpretation except
for the fact, noted above, that Baur’s figures do not
match the preserved parts of the left leg, or the im-
pression of the right — from which the missing frag-
ment purportedly was removed.

Only two options are open to us. We either accept
Baur’s interpretations on faith, for they cannot be
verified now, or we conclude that the construction of
the tarsus in Compsognathus cannot be established in
this specimen. It must be noted, however, that Baur’s
reconstruction of the astragalus is consistent with those
known in other theropods.

But a nagging question remains: What is the large
proximal tarsal? Is it the calcaneum, which it appears
to be? If so, it is unusually large. Moreover, its rela-
tionship to the tibia is unusual for a theropod in that it
clearly articulates with the distal surface of the tibia
and not just its lateral surface, as in most theropods.
This is quite evident in the impression of the left
tarsus. But, on the other hand, it also clearly articu-
lated with the fibula. If Baur (and Marsh) was cor-
rect in his interpretation, then it probably is the cal-
caneum. But at this point, I am not sure whether it is
the calcaneum, the astragalus, or the lateral part of a
fused astragalo-calcaneum. One thing is certain,
though: the mesotarsal condyle of this proximal tarsal
extends far in front of the anterior surface of the
tibial shaft, much more than in any other theropod
known to me. This would seem to indicate an unusu-
ally high degree of extension was possible at the ankle.

Baur (1882) detected three distal tarsals, which he
labeled tarsals 2, 3 and 4—5. The latter is clearly
recognizable as a flat disc closely articulated with the
proximal end of the left metatarsal IV (see Pl. 10:1).
It does not appear to have been co-ossified with the
metatarsal, but it may have been. The other two

tarsals identified by Baur, are preserved as impressions
and are not so unequivocal. As noted by Baur, the
impression of the right metatarsus seems to show two
convex cap-like elements at the upper extremities of
metatarsals II and III. But in the left metatarsus,
these same features appear to be just the proximal
convex extremities of the two metatarsals. No clear
suture or physical discontinuity separates these ends
from the metatarsal shafts, but then the tarsals and
metatarsals might have been fully co-ossified. Molds
made of the impressions of the right metatarsus show
the same condition, hence, if these two features are in
fact distal tarsals, they were completely co-ossified
with metatarsals II and III. Since at least two distal
tarsals, and usually three, are found in all other ade-
quately known theropods, I strongly suspect that this
last condition is the correct interpretation, but it must
be pointed out that the present specimen does not
permit certification.

Pes: The pes is greatly elongated, with the meta-
tarsal length somewhat greater than the median toe

x
[FTEWERTEND)
IOmm
1
IY

Figure 7: Reconstruction of the left foot of Compsogna-
thus longipes in dorsal or anterior aspect. Notice the
great length and very slender design, reminiscent of
Archaeopteryx and later birds, and suggestive of high
cursorial ability.

length. The central metatarsals (II, III, and IV) are
stout and closely appressed together. Their respective
lengths, where determinable, are given in the table of
dimensions. Metatarsal I consists of a stout wedge-
shaped bone fixed against the posterior surface of the
shaft of metatarsal II just below mid-length. Its
upper end fails to reach the tarsus by more than
20 mm, and there is no sign of a proximal portion, as
has been found in Allosaurus (Gilmore, 1920; Madsen,
1976). The fifth metatarsal is a slender curved splint-
like bone extending some 15 mm from the tarsus down
the postero-lateral aspect of metatarsal IV. There are
no distal elements of digit V. All of the first four
metatarsals have well-developed distal ginglymoid
facets and deep collateral ligament fossae, indicative
of strong, precise toe actions, and perhaps cursorial
habits (Plate 10:1).

The foot digits have the normal theropod formulae
(2-3-4-5-0) and show the usual proportions, with the
third toe the longest and II and IV somewhat shorter
and nearly equal in length, and the first toe extremely
short (it does not even reach the lower end of metatar-
sal II), and reverted to the back. The hallux ungual is
preserved oriented like those of the other toes.. How-
ever, this seems to be an artifact, as the proximal phal-
anx and the ungual obviously have been rotated about
their long axes by more than 90 degrees, as is evi-
denced by the disparate orientations of the collateral
ligament fossae on metatarsal I and the proximal
phalanx of the first digit. (The penultimate phalanx
of digit III has been similarly rotated about its long
axis by about 180 degrees, without separation from

adjacent phalanges: see Plate 10:2.) All pedal phalan-
ges are quite robust, with pronounced collateral liga-
ment fossae and strongly ginglymoid distal articula-
tions. Where observable, the proximal phalanx always
isthe longest element in each toe. The unguals are ob-
viously straighter than those of the manus, and broader,
with a more triangular cross-section and less pronoun-
ced flexor tubercles. The ungual of digit I is very short
and stubby, suggesting an almost vestigial state.

Mystery Bone.

There are a number of bone fragments, especially in
the area around the skull, that I have not been able to
identify with certainty. Most of these are too frag-
mentary, or contain no diagnostic features. One bone,
however, appears to be complete, and does have dis-
tinctive features. Yet, I have not been able to iden-
tify it. This mystery bone (Plate 10:4) lies quite iso-
lated, well above the skull and close to two cervical
ribs. It is roughly quadrangular in shape, with a
rounded articular process at one end. At first glance,
it resembles the proximal end of a dicocephalous rib,
with the articular process the capitulum and the
adjacent “shoulder” the tuberculum. However, the
other end, which is only 4.5 mm distant, is not a
broken end, but rather is a distinct articular surface.
The total length of this object is 5.85 mm, and its
maximum and minimum widths are 3.8 and 2.4 mm,
and it is complete. Its form does not match any bone
that I am familiar with, and I have no suggestions
other than that it may be a cranial element — perhaps
the ectopterygoid.

SUPPOSED SKIN-ARMOR OF COMPSOGNATHUS

Von Huene (1901) made much of a series of surface
irregularities, which he described as polygons, in the
prominent depressions along the ventral regions of the
trunk and abdomen. In the circular depression be-
tween the scapula and the left humerus, he claimed
that 15 “polygons” could be seen, most of which
were six-sided. In the oval depression just behind
this, he saw impressions of 10 more similar but larger
polygons arranged in rows. Because of their shape,
and what he termed their regularity of arrangement,
he concluded that these surface impressions were
evidence of horny skin armor in Compsognathus.
Von Huene acknowledged that no such plates are
preserved along the back, where we would most
expect skin armor, but he did claim that the neural
spines of the trunk and tail are elongated lengthwise
and strongly thickened transversely in their upper
edges, forming a row of broadened platform-supports
for the (missing) dorsal scutes. In support of this
inaccurate description (the dorsal neural spines are

not thickened distally) and supposed dorsal armor
plates, Huene alluded to the dozen or so irregularly
shaped bony ossicles found associated with some of the
caudal neural spines in Ceratosaurus (U.S.N.M.
4735), reported by Gilmore (1920), as evidence of
dermal armor in theropods. Nopcsa (1903) rejected
both of these interpretations of Huene’s, but inter-
preted other features as evidence of skin and muscle
Impressions.

I have examined the areas on the Compsognathus
slab specified by von Huene under high magnification
and various lighting conditions and have concluded
that his evidence is very doubtful. As I have attemp-
ted to show in Plate 11:1, the surface configuration in
these areas is unusual and different from that of other
areas on the slab. But I do not see any consistent
regularity of form or arrangement in any of the sites
mentioned by von Huene. It is evident, though, that
the regions concerned with von Huene’s “polygons”

have been subjected to a very different history of solu-
tion and precipitation than other regions of the speci-
men. First of all, there are the peculiar depressions
along the ventral part of the body of Compsognathus,
with their irregular “hummocky” surfaces that appear
to have been etched into the matrix. This is in sharp
contrast to the usual, very smooth, planar, and some-
times almost glassy surfaces characteristic of other
parts of the slab. Secondly, throughout these “etched
depressions”, there are irregular masses of very fine
druzy crystals, mostly of calcite, but also (surpris-
ingly) some of quartz. In some places it can be seen
that these masses of druzy crystals coincide with the
borders of the so-called “polygons”, suggesting that
these polygonal patterns reflect some aspect of crystal
growth rather than impressions of skin armor. The
general appearance of the ventral part of the body
region and the area anterior to the sacrum, is that of a
series solution cavities — vugs — dissolved into this
slab along the bedding plane containing the skeleton
of Compsognathus. This solution must have occurred
long before the slab was excavated. Following
formation of these solution cavities, masses of druzy
calcite and occasional quartz crystals formed along
the walls of these vugs, as they did within the hollow
limb bones. In short, the hummocy “polygon”
surfaces are the result of differential solution.

Further evidence in support of this explanation is
the fact that the Compsognathus slab is traversed by a
number of fractures. One prominent fracture extends
the length of the trunk and abdomen of Compsogna-
thus (see Plate 7), directly through the series of
“etched” depressions or solution cavities, then follows
along the trace of the tibia and across the left foot.
A second fracture branches off this first one in the
abdominal region and extends up through the “solu-
tion” cavity at the anterior part of the sacrum and
then follows along the course of the caudal vertebrae.
Throughout almost the entire courses of these fractu-
res, the fracture edges are rounded — clear evidence
of solution. This is especially evident in the trunk and
abdominal regions and along much of the caudal
series. Several other fractures present on the slab are
characterized by sharp edges, and apparently are of
more recent origin, not having been subjected to solu-
tion.

I suggest that prior to its excavation, the Comp-
sognathus slab was situated quite close to the surface
where it was subjected to solution by periodic ground
water percolations through these fractures. Solution
and subsequent crystalization resulted along parts of
these fracture traces, resulting in crystal-lined vug-like
cavities on this slab, and thus von Huene’s “skin
armor” is nothing more than the etched walls of these
solution cavities. That these “polygon”-lined cavities
are secondary in origin (contrary to von Huene’s

interpretation) is clearly established by the unexpected
presence of tiny, well-formed quartz crystals scattered
about on these vug walls. Hückel (1974) reported the
quartz content of the Solnhofen limestones varies up
to a maximum of 0.4°/o of total matrix, the quartz
occurring in the form of sponge spicules, tiny well-
rounded grains and rare perfect crystals. Barthel
(1976) found the rounded quartz grains (usually less
than 10 microns) to be widespread in the Solnhofen
deposits and concluded that they were eolian in
origin. The unabraded crystals, however, must be
autogenic, and most probably post-diagenic crystal-
lization derived from sources external to the Solnho-
fen matrix and introduced via bedding planes and
fractures, such as described above (see Plate 10:6).

Nopcsa (1903) dismissed von Huene’s “skin-armor”
for much the same reasons, but maintained that skin
impressions and traces of muscle fibers were preserved
in several areas around the skeleton of Compso-
gnathus. His “skin impressions” are curious, finely
granular textured areas, and his “muscle fibers” occur
as faint traces of “parallel irregular fibers” at several
locations (but not he mentioned).
Nopcsa illustrated both of these features in a drawing
of Compsognathus (1903, Plate XVIII).

every where

The granular texture is very evident throughout
most of the rib cage (except within the polygon-lined
depressions discussed earlier), between the femora,
around the skull and especially close to the left
humerus (see Plate 11:3). The contrast between this
granular-textured surface and the more normal sur-
face texture typical of other areas on the slab, is
shown in Plate 11:4. Nopcsa may have been correct
in his interpretation of this feature, but I have serious
doubts. First of all, this granular texture occurs over
much of the orbit! — as well as within the open jaws,
areas that I would hardly expect to find scaly integu-
ment. Moreover, this same texture is present, perhaps
less distinctly, surrounding all scattered and isolated
bones and is not confined to the general region of the
body. For example, it is quite clear in the areas
surrounding the several scattered phalanges of the
hands, as well as around the displaced cervical ribs.
Obviously, this is not consistent with the integument
explanation, but suggests that the bones themselves are
the controlling factor in the distribution of this curious
textural pattern. I suspect that this texture is also the
result of solution etching along the bedding plane and
is localized around three-dimensional objects lying on
that plane. Evidence for that is the presence of what
appears to be the same texture surrounding some of
the specimens of the small crinoid Saccocoma. Notice
that this granular texture is most prominently devel-
oped around the skeletal remains and Saccocoma spe-
cimens that are situated closest to the fractures that
served as solution channels. Also notice that this

texture seems to grade imperceptibly into normal
surface textures, rather than an abrupt transition at
well-defined boundaries. The organic objects on this
slab appear to have acted as centers of solution and /
or chemical activity, resulting in this granular-tex-
tured surface. Whatever its origin, though, the inte-
gument theory of Nopcsa does not explain its occur-
rence around the specimens of Saccocoma.

Concerning the “parallel and irregular fibers” seen
by Nopcsa, I must admit that I was unable to see most
of the examples he cited (Nopcsa listed seven specific
areas in which these were present). The “fibers”
between the femur and ischium, and between the
femur and tibia, and those along the base of the tail,
simply are not there! Nor are “fibers” evident above
the dorsal vertebrae, near the cervicals, or distally
along the tail. A striated or linear textural pattern

does occur proximally at the lower edge of the ischium,
and also between the right radius and ulna (see Pla-
te 11:2). In both of these sites, the striations are pa-
rallel to the adjacent bone edges. There also appears
to be a very faint lineation along the dorsal region of
the proximal caudals close to the tip of the right
dentary. Nopcsa’s “fibers” may well represent im-
pressions of soft tissues, including muscle fibers. Such
occurrences are not uncommon in Solnhofen speci-
mens. Most notable are the feather impressions in the
several specimens of Archaeopteryx and wing mem-
brane impressions in numerous pterosaur specimens
(but see also Reis, 1893). However, I am inclined to
think that these striations are merely lineated granular
texture etched into these surfaces, with the lineations
being due to the local influence of the adjacent parallel
bone margins.

COMPARISON WITH OTHER SPECIMENS REFERRED TO
COMPSOGNATHUS

At the present time, only two other specimens have
been recorded in the literature as possibly referrable to
Compsognathus. The first of these consists of three
metatarsals and a single phalanx, now in the Hum-
boldt Museum für Naturkunde, East Berlin. The
second is a nearly complete skeleton, Compsognathus
corallestris, from Portlandian limestones of southern
France. This specimen is in the Museum d’Histoire
Naturelle of Nice, France.

The Humboldt Specimen.

This specimen was first reported by Dames (1884)
and has been cited subsequently by von Huene (1925,
1926 and 1932) as questionably referrable to Compso-
gnathus. As shown in Plate 10:5, the specimen consists
of four bones, three of which appear to be metatarsals
and the fourth a proximal phalanx. These are pre-
served on counterpart slabs. First of all, it is impor-
tant to mention that it is impossible to determine from
these remains the exact nature of the complete meta-
tarsus — whether it was composed of three, four or
five metatarsals. So it is not possible to say which me-
tatarsals are preserved here (and indeed whether these
are metatarsalsratherthan metacarpals). The specimen
is preserved with the shortest bone in the middle, a con-
dition not known in the metapodials of any tetrapod,
but Dames concluded (correctly, I think) that the
longest element had been displaced and interpreted the
three as follows: mtt. I = 54 mm; mtt. II = 60 mm;
mtt III = 68 mm. This configuration does not cor-
respond with the metatarsus of C. longipes, and on the
basis of other tetrapod metatarsal construction, im-
plies that a fourth, and perhaps a fifth metatarsal are

missing. In C. longipes, metatarsal I is incompletely
formed, and metatarsals II, III and IV have lengths
respectively of 50.4, 56.0 and 51.8 mm.

If we assume that the three long bones of the Hum-
boldt specimen are metatarsals II, III and IV, and
that the longest element is metatarsal III (as in Comp-
sognathus),therelative lengths do not compare closely
with those of either C. longipes or the Nice specimen
(both of which are close in these proportions. A com-
parison of metatarsal ratios in the three specimens is as
follows:

C. longipes Nice Humboldt

specimen specimen
Mt III/Mt II — 1.11 1.14 1:27
Mtt III/Mtt IV — 1.08 1%12 1.13
MttIV/Mtt II — 1.03 1.02 1.11

Considering the fact that the Humboldt specimen is
intermediate in size between the Nice specimen and
C. longipes, these ratios suggest that the Humboldt
specimen is not referrable to Compsognathus, the
same conclusion reached by Dames. The longest bone
is too long relative to the others. This conclusion
seems to be reinforced by the single phalanx that
appears to be articulated with the shortest of the three
metatarsals (IT ?). If that articulation is correct, then
its length (20 mm) is much greater relatively than that
of the proximal phalanx of the second toe in C. longi-
pes. Consequently, my conclusion is that the Hum-
boldt specimen is not assignable to Compsognathus
longipes.

100

TABLE 2

Comparative Anatomical Dimensions of Compsognathus longipes
(Dimensions in mm.)

Type specimen

Nice specimen

(©. “corallestris”) serien
Skull length 70—75 est. 110 est. 1.42
Orbit length 19 est. 27 est. 1.52
Humerus length 38—40 est. 67 est. 1.76
Radius length 24.7 42 1.70
Ulna length 28.5 45 1657
Scapula length 38 est.
Femur length 67 est. 110 1.49
Tibia + astragalus 87.7 135.5 1.54
Fibula length 82.1
Mtt. II length 50.4 70.5 1.39
Mtt. III length 56.0 81.0 1.44
Mtt. IV length 51.8 72.0 1.39
Pubis length 60 est. 95 est 1.58
Ischium length 40 est. 70 est 1.75
Hindlimb length 264 377 1.42
Forelimb length 102 ?
Hand length 39 ?
Presacral column 236 310 + two = 342 144

Anatomical Proportions

Femur / Tibia .76
Mtt. III / Tibia .64
Humerus / Femur .56
Humerus / Tibia 43
Forelimb / Hindlimb .38
Skull / Presacral ‚30
Forelimb / Presacral .43
Hindlimb / Presacral 1.11
Skull-Orbital-Length 26

Index

.81
.59
‚61
‚50

132

1.10
24

* Ratio of Compsognathus “corallestris” / Compsognathus longipes.

The Nice Specimen.

In 1972, Bidar, Demay and Thomel reported the
discovery of a nearly complete skeleton of a small
theropod from Portlandian lithographic limestones
(Petit Plan) at Canjuers, some 60 km west of Nice,
which they assigned to a new species, Compsognathus
corallestris. This new specimen (see Plate 12) is extre-
mely similar anatomically to C. longipes, but is appro-
ximately 50°/o larger. It also is preserved in a pose
that is astonishingly similar to that of the Munich
specimen, including the parallel flexed hind legs, the
upswept tail, the 360 degree opisthotonic arc of the
cervical series, the severed head in an upside down po-
sition pointing backward, and even the presence of
stomach contents within the rib cage. So remarkably
similar are the positions of the two skeletons, one
cannot help wondering if this represents some obscure
clue about the living habits of these specimens.

I was fortunate to be able to examine the Nice spe-
cimen in some detail in 1973, thanks to the kindness of
Dr. Demay. It is not my intention here to give a full
analysis of this specimen, the original authors have
provided that. However, I think it is necessary to
examine the criteria they adopted in establishing a
new species.

In their diagnosis of C. corallestris, the authors
emphasized the larger size of this specimen and cited
varying size differences between corresponding ele-
ments as rationale for the establishment of a new spe-
cies. Another key factor was their interpretation of
the forelimb as a flipper-like appendage. In Table 2,
I have listed a number of dimensions that are available
from both specimens, together with some estimated
dimensions, and calculated the ratios of C. longipes to
C. corallestris. "The dimensions given are mine, and in
a few instances they differ from those given by Bidar,

Demay and Thomel. All measurements given in this
report were made by me (unless otherwise indicated),
with a Helios dial caliper with scale divisions to
0.05 mm. The data in Table 2 show that the various
skeletal elements of C. corallestris range from about
40°/o to 75/0 larger than the corresponding element of
C. longipes. Apparently, it was this varying differen-
ce that led the authors to conclude that the Nice spe-
cimen was distinct from C. longipes (together with the
flipper forelimb). But these varying differences might
simply reflect differing allometric growth of different
parts of the skeleton, and thus are not reliable criteria
for establishing a new taxon — especially since there
are only two specimens available for comparison.

Unfortunately, their interpretation of the forelimb
as a flipper-like structure is also highly questionable.
The forelimb of the Nice specimen is very poorly
preserved. In fact, it is so poorly preserved that it is
extremely difficult — indeed impossible — to decipher
the various components with absolute certainty. Most
of the forelimb elements are represented by impres-
sions only, many of which are indistinct, and their
identities doubtful. The construction of the metatar-
sus and manus are entirely unknown. Finally, their
evidence for a flipper consists of several “wrinkle-
like” linear undulations paralleling the forelimb
along its anterior margin. These surface features
might represent the impression of soft parts, but it
certainly does not look that way to me. Moreover,
similar “wrinkle-like” surface irregularities occur
further up on the slab which continue the same exact
trace as their “flipper imprint”. These can be seen
extending away from the loop of cervical vertebrae, to
the left and almost parallel to the lower jaw. This
“wrinkle” along side the forearm, thus seems to be
part of a much longer linear trace that extends well
beyond the skeleton and therefore cannot be part of
the specimen at all. I consider the flipper interpreta-
tion of the forelimb by Bidar, Demay and Thomel to
be poorly founded and highly improbable. (See Plate
12.)

Beyond the size differences and the questionable
flipper like forelimb, a considerable volume of anato-
mical evidence raises serious question about the validi-
ty of Compsognathus corallestris. In short, the two
specimens are nearly identical, within the limits of
imperfect preservation. In the skull, corresponding
available elements, such as the premaxillae, maxillae,
lacrymal, are the same. The dentaries also are alike,
being long, very narrow and parallel-sided. The chief
difference between the tooth-bearing elements of the
two specimens is the greater number of teeth that are
preserved in place in the Nice specimen, but I have
already remarked about the numerous displaced teeth
in the Munich specimen. Concerning the teeth, of
particular importance is the “bent” shape of the

101

anterior teeth of the premaxilla and dentary that is so
distinctive of C. longipes. The same tooth form is
present in the Nice specimen.

Because of the poor preservation of the forelimb in
the Nice specimen, no comparison with C. longipes is
possible. But the hind limbs are comparable, and the
striking similarities are most obvious, down to the
detailed construction of the pes and even the identical
form of the metatarsus — including the shape of the
vestigial fifth metatarsal. In the pelvis, the ischium is
exactly the same in both (the authors clearly misinter-
preted the lower ischial margin, placing it much too
low), with a narrow, slightly club-ended posterior
extremity and an anteriorly placed, delicate, triangu-
lar obturator process. The pubis, contrary to their
statement, is not much longer relatively than it is in
the genotype specimen. As in the Munich specimen,
the pubis is about the same length as the femur (notice
that the distal extremities of the pubis and femur
coincide in both specimens). Furthermore, although
Bidar, Demay and Thomel reconstruct a much longer
distal pubic “foot” than I believe is warranted by
the specimen, the overall shape is very much like that
in C. longipes, with long narrow cylindrical shafts and
a large distal expansion. The ilium too, was long and
low, as in C. longipes although no further compari-
sons can be made since only the upper margin is pre-
served in the type specimen. Finally, there are no
distinctions preserved in the cervical or dorsal verte-
bral column that justify specific separation of these
specimens, whereas the proximal caudals are virtually
identical, with low neural spines and an absence of
transverse processes. Even the chevrons are the same
in both specimens.

On the bases of all these striking anatomical simila-
rities, I see no justification for placing the Nice speci-
men in a separate species, especially considering the
very doubtful nature of the criteria cited by the
authors as their rationale. Accordingly, I consider
the binomial C. corallestris to be a junior synonym of
Compsognathus longipes, and refer the Nice specimen
to that taxon.

Casamiquela (1975), described a very fragmentary
specimen from the Middle Jurassic Lotena Formation
(Callovian) of Neuquen Province, Argentina, which he
referred to the Family Compsognathidae and assigned
to a new genus and species, Herbstosaurus pygmaens.
The specimen consists of impressions or fragments of a
sacrum, the right ilium and ischium, both femora a
phalanx, and other unidentified fragments. Unfortu-
nately, it is difficult to identify with certainty the
several elements that are illustrated in the two un-
labeled photographs of Casamiquela’s report. How-
ever, if the lowermost long bone on those two photo-
graphs is a femur (as I believe the author interpreted it
to be), then this specimen almost certainly can not be

102

referred to any presently known theropod species
because the “shaft” of that bone curves in the trans-
verse plane of the medially directed “femoral head”,
rather than in a para-sagittal plane as in all theropods.
On that basis alone, I consider it highly unlikely that
Herbstosaurus pygmaeus is closely allied with Comp-

IFEISSUPPOSEDIEMBRYO

The Munich specimen of Compsognathus is remark-
able ina number of features — its small size, comple-
teness, quality of preservation and certain bird-like
characters —, but perhaps the most remarkable feature
is the tiny skeleton of a small reptile well-preserved
within the rib cage of Compsognathus. In some ways,
this tiny skeleton is one of the most important features
of this specimen, for it either demonstrates viviparity
in theropods (as Marsh claimed), or it provides direct
evidence of feeding habits. Marsh (1881, 1883, 1895,
1896) was the first to notice the presence of this small
skeleton and promptly concluded that “This unique
fossil affords the only conclusive evidence that
dinosaurs were viviparous.” (My emphasis.) A few
years later, Nopcsa (1903) discussed these important
“gastronomic” remains at some length and provided
the first illustration (1903, Plate XVII). He con-
cluded that this small skeleton probably was not an
embryo on the following grounds:

1) The estimated length of 8 cm was too large for
the body cavity of Compsognathus which could
not have been more than 11 cm in length.

2) The proportions of femur to tibia.

3) The proportions of humerus to lower jaw.
4) The position of the tail and hind foot.

5) The shapes of the upper and lower jaws.
6) The shape of the pelvis.

7) Single headed ribs.

8) The strongly ossified and well-formed articula-
Nopcsa concluded that this specimen
probably was lacertilian.

tions.

I arrived at the same conclusions prior to reading
Nopcsa’s paper, for most of the same reasons, plus a
number of others. I did not arrive ata definite identi-
fication until somewhat later, but at this point it can
be stated quite categorically that the small skeleton
within the rib cage of Compsognathus is positi-
vely not anembryo, or evena young individual of
Compsognathus. In addition to Nopcsa’s points
(with the exception of # 3, which cannot be deter-
mined precisely in Compsognathus, and + 4, which is
of no significance), the following features preclude
this specimen being an embryo:

sognathus, or with any other theropod. (I suspect
that this specimen may actually be pterosaurian, be-
cause of this unusual design of the “femur”, plus the
long and unusually shallow form of the ilium — an
opinion that is shared by J. F. Bonaparte [personal
communication]).

WITHIN COMPSOGNATHUS

1) The large astragalo-calcaneum.

2) Long transverse processes on the proximal caud-
als.

3) Lepidosaurian design of the distal end of the
humerus, with pronounced entepi- and ectepicon-
dyles.

4) The very robust fibula.
5) Only two sacral vertebrae.

6) Autotomous caudal vertebrae.

In Figure 8, I have recorded the distribution of
these remains, together with my identifications. The
only important differences between Nopcsa’s inter-
pretations and mine, are his failure to recognize some
elements of the left foot, fragments of the right tibia
and fibula, the right astragalo-calcaneum, and his
mistaking the right metatarsus for a metacarpus.

The prey object lies on its left side, with its head-
end pointing toward the rear of Compsognathus. That
it actually lies within the rib cage of Compsognathus
is certain, as can be seen in Plate 13, which shows it
overlying the right ribs of Compsognathus and
overlain by the left ribs. Included are at least nine
dorsal vertebrae, 11 pairs of dorsal ribs, the left
humerus, parts of the pelvis, the entire left hindlimb
and parts of the right, plus an extremely long caudal
series including at least 50 segments. Lying out side
of the body cavity of Compsognathus, is a left man-
dible which also probably belongs to this specimen.
Nopcsa also identified a triangular impression just
above this jaw and anterior to the right femur of
Compsognathus, as a maxilla, but Iam very doubtful
of this identification — at least as the specimen now
exists. The dimensions of the various elements of this
tiny skeleton are given in Table 3.

The rib cage and dorsal vertebrae are little dis-
turbed, although details of the vertebrae are difficult
The ribs themselves are robust, surpris-
ingly so for such a small individual, but most distinc-
tive is their single-headed articulation with the ver-
tebrae. The sacrum consists of two, apparently co-
ossified segments clearly discernible between the last
rib-bearing vertebra and the first vertebra behind with
elongated transverse processes. The proximal caudals

to interpret.

L Mtt L.Tib

RlAst.-Cale

MR II DS 3
ml SI er Sg.

= R Pes
L EI] R Mt et
IO mm N Say Hu. Im
R Tib) N
DER
Preserved bone (Small reptile) aaa Bone impressions (Small reptile)
3 Restored outline (Smoll reptile)
Preserved bone (Compsognathus) SZ Bone impressions (Compsognathus)

Figure 8: Camera lucida drawing of the small reptile skeleton inside the body cavity of Compso-
gnathus. The original drawing was made by me at a magnification of 6.6, with a Wild binocular
microscope and camera lucida. Abbreviations: Ast.—Calc. — astragalo-calcaneum; C. 1, 6,
etc. — caudal vertebrae; Ca. Vert. — caudal vertebrae; D. Vert. — dorsal vertebrae; Fe. — femur;
Fib. — fibula; Hu. — humerus; Hu. Im. — Imprint of the distal end of the humerus; L. — left;
‚Mitt. — metatarsals; Pe. — pelvis; R. — right; Ra. — radius; Sa. 1. — first sacral vertebra;
Tib. — tibia; Ul. — ulna.

TABLE 3

Comparative Measurements (in mm) of the small skeleton within Compsognathus,
and the type specimen of Bavarisaurus macrodactylus*.

“stomach” Bavarisaurus

contents macrodactylus*
Humerus length 14.0 15.3
Femur length 16.8—18.0 21.15
Tibia length 16.9 19:2
Fibula length 17.2 18.8
Mtt. I length 6.8—8.1 5.5?
Mtt. II length 9.2— 10.4 9.2?
Mt. III length 10.4—11.4 11.2
Mtt. IV length 8.9—10.1 11.15
Body length 47 est. 52
Tail length 190 +

103

extend down toward the solution cavities described
earlier, then cross over the right tarsus. At this point,
the series is interrupted.

My initial attempts to decipher these stomach con-
tents were frustrated by the presence of several long
rows of bony elements in the posterior regions adja-

cent to the left foot. At first, these appeared to be
rows of vertebrae, giving the impression that there
were several small skeletons present within the body
cavity of Compsognathus. Then, because of their flat
form, and what appeared to be sculptured surfaces
and paired arrangements, I concluded that they were

104

- calcaneum

Astrogolo-

IO mm

Figure 9: Camera lucida outline drawing of the restored left hindlimb of the small reptile
shown in Figure 8, preserved within the body cavity of Compsognathus, together with my inter-

pretations of the various elements.

rows of dermal scutes. The objects are very small,
and preservation is not perfect, all of which compli-
cates the matter. But now I am absolutely certain
that these are rows of caudal vertebrae. Zygapophy-
seal processes are detectable at several places, but they
are rarely distinct. The most distinctive features are
the autotomy sutures dividing each centrum into sub-
equal anterior and posterior halves. These are well-
defined throughout most of the caudal series and
appear to have been present on all caudals, except
perhaps the first 8 or 10 segments. The caudal series
appears to be nearly complete, with only a few ele-
ments missing in the vicinity of the tenth caudal, and
perhaps a few others at several points. The tail is
preserved folded back and forth on itself in four sub-
parallel rows. At least 50 segments can be identified,
with the total length exceeding 19 cm. That is
extremely long, when compared with the hindlimb
length (femur plus tibia equals 3.4 cm, approxi-
mately).

Adjacent to the sacrum, a large L-shaped plate of
bone represents parts of the right pelvis, with the
proximal end of the right femur still in almost full
articulation with the acetabulum. Details are not
clear, but there can be no question that the L-shaped
bone is the right ilium, with perhaps a portion of the
pubis. Next to the pelvic bones, is a well-preserved
distal end of a left humerus. This, together with the
autotomous caudal structure, is perhaps the most im-
portant clue to the identification of these remains.
Very distinct here is a large radial condyle and a much
smaller trochlea for the ulna. Also evident is a large
and pronounced ventral supratrochlear fossa. But
most important are the very large entepicondyle and
somewhat less prominent ectepicondyle, which clearly
show that this is not an archosaurian humerus (Plate
14:4).

IOmm

Figure 10: Reconstruction of the left foot (in dorsal
aspect) of the small reptile, according to my identifications
recorded in Figure 9. Although my identifications cannot
be certified, this foot is readily distinguished from that of
Compsognathus in the completely formed metatarsal I, the
relatively more massive metatarsus, the stout and curved
metatarsal V (?), the relatively longer toes, and the unusual
length of the proximal (?) phalanx of the fourth digit.

The left hindlimb is nearly intact, although the foot
bones are disarrayed. 'The femur and tibia are both
stout and very nearly the same length. The tibia is
straight, the femur slightly curved. The fibula is
surprisingly robust. Articulated with the latter is an
irregular-shaped bone which I interpret as a fused
astragalo-calcaneum. Two articular facets are
evident, which appear to have been for the two epipo-
dials. The medial part, unfortunately, is concealed
beneath some of the caudal vertebrae, but in the right
ankle this region is exposed, showing what appears to
be a stout expansion or process. This does not corre-
spond to the calcaneal tuber of the crocodilian or
pseudosuchian tarsus, either in form or position. No
other tarsals are discernible in either ankle. The large
size of this element, together with its proximal posi-
tion articulated with the tibia and fibula, leave little
doubt that it is the co-ossified astragalus and calca-
neum. Important here is the fact that this bone is
quite unlike the proximal tarsals of known theropods
(see Welles and Long, 1974).

Closely associated with this tarsal bone are the
somewhat disarrayed bones of the left foot. My
identification of these foot bones is given in Figure 9.
The respective positions of the main metatarsals, and
the normal (expected) serial arrangement of the four
phalanges associated with the middle metatarsal, leave
little doubt that this is the third digit. The very long
proximal phalanx beneath, and the shorter phalanx at
its extremity, seem best linked with the fourth meta-
tarsal. Other identifications are less certain. Figu-
re 10 is my reconstruction of the foot according to the
interpretations given in Figure 9. If correctly recon-
structed, this foot is very distinct from that of Comp-

IO mm

Figure 11: The isolated left mandible that is preserved
outside of the body cavity of Compsognathus. As is shown
in Figure 1, it is closely associated with a number of displa-
ced gastralia of Compsognathus. Presumably, it belongs
to the small reptile within Compsognathus. Notice that it
bears a distinct coronoid process and that it is relatively
less slender than that of Compsognathus. See also Pla-
te 14:3.

sognathus, but it is surprisingly similar to that of ano-
ther Solnhofen taxon.

The tiny jaw lying outside of Compsognathus’ body
cavity, most probably also belongs to this specimen,
although that cannot be certified. In support of this,
there are no other remains of small vertebrates on the
Compsognathus slab, and the mandible is of appro-
priate size. Two features of this mandible distinguish
it from that of Compsognathus: the presence of a
well-developed coronoid process, and the greater
degree of forward taper of the dentary. Tiny sharp,
symmetrical, conical teeth are present, apparently
with thecodont (or possibly pleurodont) implantation.
No evidence of the “bent” tooth form of Comp-
sognathes is visible. (See Plate 14:3.)

Now that I have emphatically rejected the “con-
clusive” evidence of Marsh, and his embryonic iden-

IO mm

Figure 12:

Bovarisaurus

mocrodactylus

Camera lucida drawing of the left hindlimb of the type specimen of Bavarisaurus

macrodactylus, for comparison with the hindlimb elements of the small reptile illustrated in Figu-
res 8, 9 and 10. The slight differences in pedal proportions may be due to erroneous interpreta-
tions of the foot elements in the Compsognathus stomach contents, or to ontogenetic differences, or,

most likely, to taxonomic differences.

106

TABLE 4

Some Available Skeletal Proportions of the
Small Reptile Skeleton Inside Compsognathus, Compared
With Other Solnhofen Lower Tetrapods.

Femur / Tibia Femur / Humerus Tibia / Mtt. III
“Stomach contents”
of Compsognathus 1.00 — 1.06 1.20 — 1.28 1.48 — 1.66
Bavarisaurus macrodactylus 1.10 1.38 1.76
(B. S. P. 1873 III 501)
Homaeosaurus brevipes 1.25 1.39 1.48
(B. S. P. 1887 VI 2)
Homaeosaurus maximiliani 1.06 1.19 1.39
(B.S.P. AS I 565)
Kallimodon pulchellus 1.24 1.30 1.43
(B. 5. P. 1887 VI 1)
Eichstaettisaurus schroederi 1.40 1.32 1.46
(B. S. P. 1937 11)
Ardeosaurus digitatellus 1.68 1:33 1.46
(B.S.P. 1923 I 501)
Palaeolacerta bavarica 1.12 est. 1.32 est. _
Mus. Maxberg
Alligatorellus beaumonti 1.03 1.17 2.0
(B. S. P. 1937 I 26)
Atoposaurus oberndorferi 1.03 1.13 1.97

(B.S. P. 1901 I 12)

tity of this skeleton, the question remains: What is it?
Can it be identified? I believe that it is identifiable.
After examining various other Solnhofen specimens,
and reviewing the literature on other small tetrapods
from the Solnhofen beds, I am convinced that these
remains are those of a small individual of the lacer-
tilian, Bavarisaurus. Recognizing that the small size
of this specimen may be due to immaturity, compari-
son of limb proportions and other size factors must be
viewed with skepticism. Nevertheless, the ratios of
femur to tibia, femur to humerus and tibia to metatar-
sus (Table 4) agree quite closely with those of the
type specimen of Bavarisaurus macrodactylus (Hoff-
stetter, 1953), and several species of Homoeosaurus.
Reference of these remains to any species of Homoeo-
saurus is precluded by the thecodont (or perhaps pleu-
rodont), rather than acrodont, dentition.

In addition to this dimensional evidence, further
support for identifying these remains as Bavarisaurus
is found in the several distinctive parts of the skeleton
preserved. The foot, as I have reconstructed it in
Figure 10, corresponds quite closely with that of Ba-
varisaurus macrodactylus (see Fig. 12), except for the
unknown state of the fifth toe in the present specimen.
In addition, Bavarisaurus possesses a large, irregular-
shaped astragalo-calcaneum (see Fig. 40C of Cocude-
Michel, 1963), although preservation does not permit
recognition of close morphological similarities. "These
elements are illustrated in Plates 13 & 14. Also impor-
tant here is the distal end of the humerus, which is

very similar to that of Bavarisaurus (see Fig. 2B, Hoff-
stetter, 1964), as I have attempted to show in Plate 14:
48&5. Finally, the construction of the numerous
caudal vertebrae seem to provide the most compelling
evidence of all for identifying these remains as Bavari-
saurus cf. macrodactylus.

As shown in Figures 8 and 13, an extremely long
series of caudal vertebrae are folded back and forth on
itself into four sub-parallel rows. Microscopic exami-
nation of these vertebrae reveals that all except the
most proximal centra are marked by complete and
well-defined autotomy sutures. Each suture traverses
the middle of the centrum in a nearly vertical course,
then bends sharply forward in its upper part (Pla-
te 14:1). This identical structure (see Plate 14:2), and
what appears to be the same vertebral morphology,
are found in all preserved caudal vertebrae of the type
specimen of Bavarisaurus macrodactylus (see Fig. 1b,
Hoffstetter, 1964). Furthermore, the morphology and
disposition of the long transverse processes of the pro-
ximal caudals in the small specimen are like those of
Bavarisaurus. The only apparent difference between
the two specimens is the extremely long tail of the
small individual and the apparently relatively short
tail in the type of Bavarisaurus. The latter, however,
looks as though it might have been shortened as a
result of tail autotomy: the last distinct vertebra is
still quite large, causing the tail extremity to have a
somewhat “stubby” appearance. Also, there is a faint
impression distal to the last recognizable caudal which

Last Preserved
Coudal

First
Caudal

Autotomy Sutures

(enEranenenenenan

IO mm b

Figure 13: Outline drawing of the folded caudal series of the small reptile, taken from Figure 8.
Missing segments are restored by dashed outline. The heavy arrows register my reconstruction of
the caudal sequence, progressing from the first caudal to the extremity. Notice the forward flexure

107

of the autotomy sutures.

looks to be that of a fleshy stump-like tail extremity,
reminiscent of regenerated tail stumps that are com-
monly found in modern autotomous lizards. Another
aspect of the caudal anatomy preserved in these two
specimens that may be important is that all caudal
centra, except the most proximal segments, seem to be
autotomous. In most modern autotomous lizards,
autotomy fracture planes occur throughout the caudal
series (except for a few proximal segments), but func-
tional autotomy may be confined to a limited region of
the tail by progressive ontogenetic fusion at the auto-
tomy cartilage septa throughout the other parts of the
tail (Etheridge, 1967).

The extraordinary length of the tail in the specimen
within Compsognathus appears highly improbable at
first glance, but all I can do is to present the evidence
as Iseeit. In Figure 13, I have traced the sequence of
caudals (line of heavy arrows) as I interpret it, from
the sacrum through four 180 degree bends, to the
delicate tail extremity. A minimum of 50 segments
can be discerned, and the total length of this folded
series is not less than 19 cm. That is more than four
times the probable body length of 46 mm (estimated
from the proportions of the larger-sized type specimen
of Bavarisaurus). Improbable though such an extreme
tail length seems, I am convinced that it is correct.
The only other possible explanation is that more than
one caudal series is present among these stomach con-
tents. Against that interpretation, I offer the follow-
ing evidence: 1) There is no other evidence that more
than one individual is preserved within the the body
cavity of Compsognathus; 2) Notice that the complete
sequence as interpreted in Figure 13 consists of pro-
gressively smaller vertebrae proceeding toward the tail

tip; 3) Notice also, that the dorsal flexure of the auto-
tomy sutures consistently bend in a forward direction
— toward the sacrum — showing that two of the four
rows are oriented in one direction (with the anterior
end toward the rib cage) and the other two rows are
oriented in the opposite direction (with the anterior
end pointing away from the rib cage). This verifies
my interpretation that the “ends” of the vertebral
rows actually are “folds” — 180 degree bends, as
illustrated in Figure 13; 4) And finally, there is a
physical break at an autotomy fracture plane at
each of the three proximals folds in the tail. From
these facts, I conclude that these parallel rows of
vertebrae represent a folded, but nearly continuous
caudal series of a single individual. Thus the extra-
ordinary tail length is correct.

Other parts of the so-called Compsognathus embryo
skeleton are much too fragmentary to be of reliable
value in support of this identification, but the pelvic
bone does seem to resemble the L-shaped ilium of the
type specimen of Bavarisaurus. Also, the ribs of Ba-
varisaurus are quite robust in construction (but not
pachyostostic), and are single-headed, as in the small
specimen. A very small fragment of the anterior tip
of the left dentary of Bavarisaurus preserves small,
sharp, conical pleurodont teeth, which are very similar
to the teeth in the tiny jaw on the Compsognathus
slab. The latter, however, appear to be thecodont,
although this mandible lies on its medial surface and a
pleurodont implantation cannot be ruled out.

In summary, a surprising amount of anatomical and
proportional evidence establishes the identity of
Compsognathus’ last meal as a young individual of
Bavarisaurus (cf. macrodactylus).

108

COMPSOGNATHUS THE ANIMAL

The Munich Specimen: Adult or Juvenile?

Curiously enough, the small size of the type speci-
men of Compsognathus has never provoked published
inquiry about the maturity of this individual, al-
though the question has often been debated in class-
room discussions. In fact, the literature on Comp-
sognathus seems to meticulously avoid the subject,
tacitly treating the matter as though there could be no
question, and accepting the Munich specimen as an
adult individual. That conclusion is far from estab-
lished, as the discovery of the Nice specimen clearly
demonstrates.

As was mentioned earlier, the Munich specimen
gives the appearance of being a mature individual, at
least in the texture and completeness of the bones of
the skeleton and the apparently closed sutures of the
vertebral column. However, other factors (besides its
small size) suggest that it may not be a fully mature
specimen. But with only two specimens available for
comparison, no definitive statement can be made.

Three distinctive features of C. longipes suggest, but
do not prove, that this is not a fully adult individual:
1) The relatively large skull; 2) The dispropor-
tionately large orbit; 3) The relatively long hindlimbs.
As is well-known, the head is disproportionately large
in all hatchling or new-born amniotes, but in some
theropods (Megalosauridae, Tyrannosauridae) the
skull remained disproportionately very large in the
adult stage. A comparison of skull and post-cranial
proportions of Compsognathus and various other
theropods (given on page 82), unfortunately proves to
be inconclusive as regards the relative ontogenetic age
of the Munich specimen.

Even though the occipital and posterior portions of
the temporal region are not preserved, the orbit can be
seen to be relatively enormous compared with the
estimated length of the skull (70 to 75 mm). Using

Kälin’s (1933) skull — orbital — length index
(19 mm x 100) gives a relatively high value of 26,
72 mm

which by comparison with Kälin’s numbers suggests
a juvenile state. Skull — orbital — length indices for
other theropods are given in Table 5, but again, comp-
with Compsognathus conclusive,
because we are comparing different taxa rather than
individuals known to be of differing ages, but belong-
ing to the same species. Yet, the type specimen of
Compsognathus does have one of the highest skull —
orbital — length indexes among theropod specimens.

Finally, as was noted earlier, the hindlimb length of
Compsognathus is relatively long (but not excessively
for theropods) and is reminiscent of precocial limb
proportions in the young of certain cursorial animals
(horse, deer, antelope, etc.). Yet, for the simple rea-
son that the hindlimb is not unusually long for a
theropod (of any size) clearly indicates that we should
not consider long limb length per se as evidence of
immaturity. Comparison with the only other speci-
men certifiably referrable to Compsognathus (the
French specimen, “C. corallestris”) offers little addi-
tional evidence in this regard. For example, the ratio
of total hindlimb length to presacral length is approxi-
mately the same in “C. corallestris” and C. longipes
(1.10 vs 1.11), even though the French specimen is
50°/o larger. (I obtained a different presacral length
than the authors of “C. corallestris”, measuring

arısons are not

31 cm, with two cervicals missing or unmeasurable.
Adding an average vertebral length of 16 mm for each
of the two missing segments, I estimated the total pre-
sacral length to be 34.2 cm.) Assuming my vertebral
length estimate to be reasonably close, there is no dif-
ference in the relative hindlimb lengths of these two
specimens. If these two specimens belong to the same
species, as I believe, this indicates that either there was

TABLE 5
Skull — Orbital — Length Indexes of Some Theropods.

Compsognathus longipes (Holotype) . -. - . . 26
Compsognathus longipes (Nice specimen).. . . . 24
Ornithomimus altus 26
Ornitholestes hermanni . 25
Gallimimus bullatus . 24
Velociraptor mongoliensis 23
Saurornithoides mongoliensis 22
Allosaurus fragilis 14
Tyrannosaurus rex 10

little allometric change in hindlimb length during
growth, or both specimens are essentially mature.
Thus, on the basis of just these two specimens, it is not
possible to decide whether long hindlimb length is a
juvenile condition or an adult cursorial adaptation.

Returning to skull size, on the basis of my estimates
of skull length and presacral column length, the skull
of “C. corallestris” appears to have been relatively
larger (.35 of presacral length) than that of C. lon-
gipes (.30 of presacral length), even though the latter
is smaller. The difference could well be due to errors
in my estimates, rather than to an unlikely positive
allometric skull growth. With regard to skull — orbit
— length index, C. longipes and “C. corallestris”
have fairly close indexes (26 and 24). The slightly
lower index for the larger French specimen suggests
more advanced maturity.

With such a limited sample, none of these para-
meters can be considered as conclusive evidence of
relative age, but I am inclined to believe that the
Munich specimen of Compsognathus is an immature,
although probably not a juvenile, individual. That
belief is based primarily on the enormous size of the
orbit, the larger size of the Nice specimen, and the
texture and fully ossified state of the skeleton.

Reconstructionand Life Habits

Attempts to reconstruct posture and life habits of
extinct animals are educated guesses at best, and must
always be viewed as such. The present effort is no
exception. Speculations about the functional signifi-
cance of particular skeletal features are even more
suspect, unless one can point to a nearly identical
modern analogue. Because of its chicken-size, (esti-
mated live weight, 3-35 kg), and certain
bird-like features in its skeleton (foot, hind leg,
skull ?), there is a natural tendency to turn to modern
ground-dwelling birds for our analogues in reconstruc-
ting life style and posture in Compsognathus. Cer-
tainly, that seems reasonable grounds for claiming
bipedal carriage in this creature. But, as Figure 14
shows, there is much else about Compsognathus that is
not bird-like, and this is where my reconstruction
falters. Whether my reconstruction in Figure 14 is
any closer to the truth than the earlier reconstuctions
by Huxley in 1876 (see Marsh, 1895), Marsh (1895,
1896) and von Huene (1925) can never be known, but
I offer it as my best estimate of the posture and skele-
tal organization of Compsognathus longipes.

The osteology of the hind and fore limbs establish
conclusively that Compsognathus was a biped, and in
all probability, an obligate biped. The length of the
forelimb, although not as shortened as has been gener-
ally held (.43 of presacral column length), when con-
sidered against the greater length of the hindlimbs,
makes a four-legged stance rather awkward, but per-

109

haps not impossible. However, the reduced two-
finger construction of the manus, while not short in the
absolute sense, appears to be a specialized adaptation
incompatible with quadrupedal locomotion. On the
other hand, we can be quite certain that the forelimbs
were used to some extent in raising the animal from a
resting pose, as well as in predatory activities.

At first glance, the hindlimbs appear to be unusually
long, but when compared with the length of the pre-
sacral column, they are comparable to those of other
theropods. The relative proportions of femur to tibia
and tibia to metatarsus suggest that Compsognathus
may have been only a moderately fast cursorial biped.
That interpretation, however, is strongly contradicted
by the stomach contents, which are discussed later.
Using my estimate of femur length of 67 mm, the
femur /tibia ratio is a moderately low .76, which is
less than that of Ornithomimus (= Struthiomimus) at
.88, but still much greater than that of fleet-footed
struthious birds such as Struthio (.46) and Casuarius
(.57). The metatarsus / tibia ratio, the commonly
accepted index of cursorial ability, is a moderate .63,
close to that of Ornithomimus (.68) and Ornitholestes
(.73), but well below that of Struthio (.95) and Ca-
suarius (.85). So, contrary to earlier suppositions,
Compsognathus appears not to have been as fleet-of-
foot as some other “coelurosaurian” theropods. In
fact, this last ratio is surprisingly close to that of
graviportal “carnosaurian” theropods like Alberto-
saurus (= Gorgosaurus), although Compsognathus
obviously cannot be categorized as graviportal. Per-
haps this “graviportal” index, and the stomach con-
tents of Compsognathus, are important reasons for us
to re-examine the theoretical basis of designating cer-
tain limb element ratios as “graviportal” and others
as “cursorial”.

Compared with the hindlimb, the forelimb defi-
nitely is reduced, measuring only 38%/o of hindlimb
length and 43/0 of presacral vertebral length. This
compares with typical non-tyrannosaurid forelimb /
presacral ratios that range from .50 to .60. Despite its
somewhat reduced length, though, the forelimb ele-
ments of Compsognathus are quite robust and the
hand equals almost 40°/o of the total forelimb length.
All of this suggests an active and powerful role for the
anterior appendage. This interpretation is reinforced
by the relatively large coracoids, the very prominent
acromion and the stout scapula. The acromion and
coracoids especially, suggest the presence of a power-
ful pectoral and deltoideus musculature, which in turn
implies powerful antero-ventral adduction and flexion
of the forelimb and hand, and strong elevation of the
humerus. Presumably, these actions were critical in
the prey-catching process, but exactly how is not clear.

The unique design of the manus — long, but re-
duced to just two functional fingers (one of which has

110

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a reduced phalangeal formula) — is difficult to under-
stand, especially when considered in terms of the more
usual three-fingered hands of most other theropods, or
the more primitive five digit manus. First thoughts
are that the manus of Compsognathus was not suited
for raptorial activities, and this seems to be substan-
tiated by the rather straight and short form of the
unguals (see Figs.5 and 6), and the reduced phalan-
geal count of digit II, as compared with the ungual
form of other theropods. However, that interpre-
tation seems to be in conflict with the robust construc-
tion of the arm and hand, and the prominent elements
of the shoulder girdle. My conclusion is that the hand
was specialized for some role, but probably not the
usual prey-catching action usually envisioned for most
theropods. But what kind of activity requires a long,
stout, two-fingered hand? Is it possible that it served
as a digging structure — to tear apart insect nests, ant
hills or termite mounds? That seems unlikely in view
of the stomach contents.

That Compsognathus was a predator, there can be
no doubt. The dentition alone indicates that. Since
virtually all modern flesh-eating vertebrates are op-
portunistic feeders, we can be certain that Compso-
gnathus ate whatever small creatures it could find and
catch. For that reason, and because of its small size,
we should conclude that Compsognathus probably
was insectivorous, at least in part. But in addition,
the tiny skeleton preserved within Compsognathus is
dramatic and indisputable evidence that Compsogna-
thus preyed on small vertebrates as well. Identifica-
tion of these stomach contents as Bavarisaurus (cf.
macrodactylus) provides specific critical evidence
about the food-seeking habits and skills and the food
preferences of Compsognathus that go far beyond any
previous intuitive deductions about the predatory
habits of any other theropod (Deinonychus included).
Dinosaur remains that contain recognizable stomach
contents, let alone identifiable food items or prey re-
mains, are extremely rare. So whatever can be de-
duced about the adaptations and live nature of Bava-
risaurus provides unusual specific insight into the
hunting skills and behavior of Compsognathus.

Overall, the relative proportions of the tail, the
limbs and feet of Bavarisaurus are quite similar to
those of modern lizards that are noted for their speed
and/or agility, such as certain teiids, iguanids, lac-
ertids and agamids. The type specimen of Bavarisau-
rus macrodactylus (B. S. P. 1873 III 501) displays the
usual lacertilian disparity of hindlimb vs. forelimb
length. But more important, is the fact that the pes is
markedly longer than the manus. Most important of
all, though, is the extremely long tail of Bavarisaurus,
as can be seen in the remains preserved within Comp-
sognathus (see Fig. 8 and Plate 13). Romer (1956)
observed that long tails are most common among

111

arboreal lizards. While that is true, long tails are
also typical of many of the fastest-running ground-
dwelling species, such as some teiids and iguanids.

In Figure 15, I have plotted the major body par-
ameters of some of the longest-tailed living lacertilian
species for comparison with those of Bavarisaurus
(taken from both the type specimen and the remains
within Compsognathus). Of interest here are the
several species (and there must be others) in which
the tail is relatively longer than in Bavarisaurus.
For example, theagamids Gonocephalus godeffroyi and
Calotes calotes, among the longest-tailed lizards
known, are very active climbing and leaping forms.
Agama agama also is an active climber, but perhaps
not as quick as Gonocephalus and Calotes. Iguana
iguana and Lacerta viridis also are long-tailed, al-
though not to the extent of the two agamids included
above, but the iguanid, Basiliscus vittatus has a tail
length comparable to that of Calotes calotes. Iguana
iguana is a good climber, but also is a fast runner.
Lacerta viridis is predominantly a running form, as is
the teiid Cnemidophorus. Mertens (1960) recorded
that Cnemidophorus limniscatus was capable of speeds
up to 15 miles (23km) per hour over short distances.
Basiliscus also is noted for its high running speed, and
its ability at maximum velocity to run on its hind legs
(notice [Fig. 15] the extreme disparity of hindlimb
vs. forelimb length, as compared with another fast-
running form, Cnemidophorus sexlineatus). From
these data, I conclude that long tails from 3 to 5 times
the body length, are found in both highly cursorial
and active climbing lizards.

The question of interest here, is, can we determine
whether Bavarisaurus was predominantly a fast-
running ground-dweller, or an agile climber? I think
we can.

Notice in Figure 15 that the hands and feet of
climbing forms (the agamids and /guana) are not so
disproportionate, and in Agama they are of nearly
equal length. Presumably, this is a reflection of the
need for enhanced (enlarged) grasping powers of the
manus in climbing species. In the highly cursorial spe-
cies, on the other hand, the manus is conspicuously
shorter than the pes — extremely so in Cremidopho-
rus, and somewhat less so in Basiliscus and Lacerta.
On this basis, the elongated foot and relatively short
hand of Bavarisaurus suggest that it probably was a
fast-running ground lizard, rather than a habitual
tree-dwelling or climbing species.

While the data of Figure 15 represent only a small
sampling of the Lacertilia, and may be viewed as
merely suggestive but not conclusive as regards the
living habits of Bavarisaurus, one additional piece of
evidence preserved in the “consumed” specimen
strongly supports the cursorial interpretation. That
evidence is the autotomy fracture septa of the caudal

112

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vertebrae. Autotomy is far from rare in modern
lizards, but it does seem to occur most commonly in
ground -dwelling species.

On the basis of the autotomous and very long tail,
and the hand and foot proportions, the picture that
emerges of Bavarisaurus is one of a very fast-running,
predominantly ground-dwelling lizard, perhaps simi-

APFINITTIES OF

Early attempts, especially those by Huxley (1870),
to decipher the affinities of Compsognathus, were
confounded by the facts that the tibia was signifi-
cantly longer than the femur and the cervical verte-
brae were viewed as “elongated”, conditions that
were unknown in other then-known dinosaurs. These
conditions led Huxley to propose his higher taxon,
Compsognatha, which he ranked equally with the
Dinosauria. The problem was that almost no other
remains of small dinosaurs, let alone what we would
now identify as “coelurosaurian” theropods, were
known at the time. Not until the 1880’s did frag-
mentary remains of small theropods begin to surface:
Coelurosaurus, 1865; Coelurus, 1879; Hallopus, 1881;
Thecospondylus, 1882; Aristosuchus, 1887; Coelo-
physis, 1889; Ornithomimus, 1890; Agrosaurus and
Calamospondylus, 1891. But none of these finds were
anywhere near as complete as the specimen of Comp-
sognathus. Most consisted of only a few vertebrae, or
teeth, or limb fragments. Only the specimens of Hal-
lopus and Coelurus preserved sufficient parts to permit
meaningful comparisons. Thus, it is not surprising
that early works often allied Compsognathus with
Hallopus, and somewhat less frequently with Coelu-

113

lar to the living species of Cnemidophorus. From this
unusual evidence, it is clear that Compsognathus was
equipped to pursue and catch very fast-running and
agile prey. If you have ever attempted to run down
and catch specimens of Cnemidophorus (as I have) or
Basiliscus, you can appreciate what that involves —
keen sight, rapid acceleration, high speed and quick
reaction and maneuverability.

COMPSOGNATHUS

rus. But, it is important here that proper credit be
given to Huxley. Despite these facts, and its diminu-
tive size, as early as 1868 Huxley perceived that the
affinities of Compsognathus were among or close to
the giant dinosaurs.

Walker (1970) established conclusively that Hallo-
pus has nothing whatever to do with theropods, but is
an early crocodilian. This leaves Coelurus and a rela-
tively small number of adequately founded theropod
taxa for comparison with Compsognathus, out of a
total of 40-odd genera listed by Steel (1970) under the
“Coelurosauria”. These other taxa are: Coelophy-
sis, Coelurus, Halticosaurus, Ornitholestes, Procomp-
sognathus and Segisaurus. While the type specimens
of other small theropods may be adequate bases for
establishing the respective taxa, I consider the types of
Avipes, Velocipes, Agrosaurus, Aristosuchus, Calamo-
spondylus, Caudocoelus, Coelurosaurus, Thecocoelurus
and Thecospondylus to be quite inadequate for assess-
ing the affinities of Compsognathus. And for obvious
reasons, there can beno close relationship between
Compsognathus and oviraptorids, ornithomimids or
dromaeosaurids, so these will not be reviewed here.

Figure 15: Diagramatic comparison of the main skeletal components of Bavarisaurus cf. macro-
dactylus (the stomach contents of Compsognathus) with those of selected modern, long-tailed
lizards. All skeletons are represented with equal body lengths to facilitate comparison of relative
tail lengths. Data on Bavarisaurus are derived from the type specimen (B. S. P. 1873 III 501) and
the remains preserved within the rib cage of Compsognathus. Data on the recent lizard species
were obtained from specimens in the Bayerische Zoologische Staatssammlung, through the courtesy
of Dr. U. Gruber. The long-tailed agamids, Gonocephalus and Calotes, are extremely active and
agile climbers. /guana also is a good climber, but is a speedy ground runner as well. The other
species illustrated are predominantly ground-dwelling forms, all of which are fast over short
distances. Fastest of all, are the teiid Cnemidophorus and especially the iguanid Basiliscus. Long
tails seem to be typical of highly active lacertilians and not distinctive per se of either predo-
minantly climbing species, or highly cursorial forms. However, there is other evidence in the data
plotted here that is suggestive: there appears to be less disparity of fore and hind foot length in
the climbing forms (agamids, /guana) than there is in the fast-running ground dwelling kinds

(Cnemidophorus and Basiliscus).

114

Compsognathus is distinct from each of six pre-
viously mentioned genera as follows:

1) Coelophysis (Late Triassic): High tooth count

(>) deep mandible, four-fingered manus, femur

and tibia sub-equal, no distal pubic expansion or
expansion is very small, dorsal vertebrae are pleu-
rocoelous.

2) Halticosaurus (Late Triassic): Deep mandible,
five-fingered manus, femur longer than tibia, dorsal
vertebrae possibly pleurocoelous.

3) Procompsognathus (Late Triassic): Broad apron-
like pubic plates as in pseudosuchians, with a long
mid-line symphysis and lacking a distal expansion.

4) Segisaurus (Late Triassic): Presence of clavicles
and an interclavicle (?), three-fingered manus, and
what appears to be a prominent calcaneal tuber.

5) Coelurus (Late Jurassic): Cavernously pleurocoe-
lous dorsal vertebrae, and extremely elongated me-
tatarsals.

6) Ornitholestes (Late Jurassic): Three-fingered ma-
nus, and femur longer than tibia.

The distinctive features of Compsognathus are: The
very slender or shallow mandible, “bent” form of the
anterior teeth, “sub-equal” length of cervical and
dorsal vertebrae, pleurocoelus cervicals and non-
pleurocoelous dorsals, very short ischium (relative to
pubic length) and two-fingered construction of the
hand. The most important of these, in my opinion, is
the specialized design of the manus, and on that basis
alone I place Compsognathus in its own separate fa-
mily, Compsognathidae. My rationale for this is first,
no other theropod is presently known which posesses
this unique manus morphology, and second, this con-
struction of the manus precludes Compsognathus being
ancestral to any other known theropod. I have no
doubt that some critics will point out that the exact
design of the manus in Compsognathus is open to
question, but I think it has been demonstrated above
that the hand could not have consisted of more than
two fingers, both of which apparently were construc-
ted of two phalanges. Contrary to the view of some,
that the phyletic loss of structures should not be con-
sidered as specialized or advanced conditions, I believe
the two-fingered hand of Compsognathus does repre-
sent a specialized adaptation. But more important,
the unique phalangeal formulae (2-2-0) establish that
this is unrelated to the digital reduction characteristic
of later deinodonts (Albertosaurus, Tarbosaurus and
Tyrannosaurus), where the formulae are 2-3-0.

If the evidence for close relationship between
Compsognathus and known “contemporaneous”, or
later theropods is preclusive, as I believe it is, then
evidence for close affinity with earlier taxa is less con-

clusive, although suggestive. The presence of a two-
fingered manus precludes “close” relationship with
later three-fingered forms, but it does not negate pro-
ximity to preceding three-(or more)-fingered kinds.
Among the pre-Compsognathus theropods mentioned
above, Procompsognathus triassicus is the most inter-
esting. The type specimen (S.M.N.S.12591),
named but not described by Fraas (1913), consists of a
dorso-ventrally crushed incomplete skull and mandi-
bles, a complete right hindlimb and foot, left femur,
both pubes, the left scapulo-coracoid, a radius and
ulna, ten dorsal vertebrae plus ribs, five or six cervicals
and eight or nine caudals. Additional material (S. M.
N. S. 12 352) found later, consisting of an incomplete
manus and pre-orbital parts of a somewhat larger
skull, were referred to this species by von Huene
(1921 a), but his referral must be viewed with skepti-
cism.

In several respects, the type remains are quite simi-
lar to those of Compsognathus longipes, most notably
in the construction and proportions of the foot and
dorsal vertebrae, and to a lesser extent, the hindlimb.
The chief differences lie in the distincetly primitive
design of the pubes (broad transverse plates meeting in
a long mid-line symphysis with no distal expansion)
and the long transverse processes of the proximal cau-
dal vertebrae. The femur to tibia ratio also differs
slightly (.83 in Procompsognathus to .76 in Compso-
gnathus). Although the pubis is relatively much
longer than in most pseudosuchians, approaching the
length of the femur as in theropods, its broad trans-
verse, apron-like form is reminiscent of the pseudosu-
chian condition. This primitive design of the pubis
contrasts with the advanced design of the foot, which
is remarkably similar to that of Compsognathus (see
Fig. 16).

The type skull of Procompsognathus is moderately
crushed dorso-ventrally, making comparison with the
laterally crushed skull of Compsognathus somewhat
difficult. The nares are indistinct, a large triangular
antorbital fossa is present containing what appears to
be two disparate sized fenestrae, and the orbit is quite
large. The mandibles appear to be very shallow, as in
Compsognathus, but the teeth are of typical theropod
form, with no sign of the “bent” shape characteristic
of the anterior teeth of Compsognathus.

Von Huene (1921 a), considered Procompsognathus
to be a “coelurosaur” — presumably close to Comp-
sognathus — and over the ensuing years it has con-
sistently been placed with other small or lightly-built
Triassic theropods (or presumed theropods, such as
Hallopus). That would seem to be a reasonable as-
signment in view of the distinctly theropod-like design
of the pes. But the apparently pseudosuchian-like
construction of the pubis, together with the indeter-
minate condition of the acetabulum and the absence of

Coelophysis

Compsognathus

115

Procompsognathus

Figure 16: Comparison of foot morphology in Compsognathus longipes, Procompsognathus
triassicus (S. M. N. S. 12591) and Coelophysis longicollis (A. M. N. H. 7223). All three are
drawn with the third metatarsals equal in length to eliminate size differences and to show the rela-
tive proportions of the digits to the metatarsus. The similarities are obvious. The foot of Comp-
sognathus might have been derived from either Procompsognathus or Coelophysis — or a common
ancestor of these Triassic forms. The vertical lines equal 20 mm for all three specimens, to show

relative sizes.

other pelvic bones, raises the question as to whether
this specimen is truely theropodan, or perhaps theco-
dontian. That question takes on added significance in
the light of recent discoveries of the small pseudosu-
chians (?) Lagosuchus and Lagerpeton (Romer, 1971,
1972) from the Middle Triassic of Argentina. Both of
these taxa possess an elongated foot with reduced
digits Iand V, and what appears to be near meso-tar-
sal grade ankle joints.

Until a very much needed, new and detailed analy-
sis of Procompsognathus is available, little can be said
about its placement, or its possible relationship to
Compsognathus. However, I suspect that these re-
mains represent those of a late, but advanced (in foot
structure) pseudosuchian not ancestral to any thero-
pod. Compsognathus appears to represent a dead-end
theropod line derived from the primitive podokesau-
rids (Coelophysis, Halticosaurus). The foot of
podokesaurs is typical theropod in its construction and
comparable to that of Procompsognathus (see Fig. 16),
but the pelvis is more advanced than that of Procomp-

sognathus, at least in the form of the pubis. This last
point, together with overall primitive theropodan
anatomy of Coelophysis (as the best-known podoke-
saurid), qualify podokesaurids as possibly ancestral to
Compsognathus, coelurids and perhaps other thero-
pods.

One final observation concerning the possible affini-
ties of Compsognathus, is required here. Elsewhere
(Ostrom, 1973, 1976b), I have argued that Archaeop-
teryx and later birds evolved from a “coelurosau-
rian” ancestry, and I raised a speculative question
(1974) “whether some theropod dinosaurs
might have had feathers”. As a small theropod,
Compsognathus cannot be very far removed from the
theropod line that gave rise to birds, but its reduced
manus, as well as its contemporanceous occurrence
with Archaeopteryx, exclude it from direct ancestry of
Archaeopteryx and later birds.

small

If the speculative question about feathered “coelu-
rosaurs’” can ever be answered, the Munich specimen

116

of Compsognatbhus is the critical specimen to examine.
It is the smallest of known theropods and it comes
from the same Solnhofen limestones (but not exactly
the same facies) as the specimens of Archaeopteryx
with their distinct feather impressions. There are no
feather impressions — nor any evidence whatever that
is suggestive of feathers — anywhere on the Compso-
gnathus slab. The reader can be sure that I made an
exhaustive examination, under various lighting condi-

tions, in search of evidence for feathers, but to no
avail. If feathers had been present in Compsogna-
thus, it is inconceivable to me that no evidence of them
would be preserved, considering the complete and al-
most undisturbed manner in which the skeleton is pre-
served, the fine details of the skeleton, and the pre-
sence of portions of one horny claw. But the fine-
grained matrix shows nothing. Thus, I conclude that
Compsognathus almost certainly was not feathered.

117

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TAFELN

Fig.
Fig.
Fig.
Fig.
Fig.
Fig.
Fig.
Fig.
Fig.

Fig.
Fig.

Fig.

a va ww

Plate 1

: Miliammina fusca (Brapy). — a, side view: X 130; b, apertural detail: X 226 [Chuy

N° 364: 122.10—124.00 m].

: Textularia gramen d’Orsıcny. — a, side view: X 130; b, detail of apertural region:

X 289 [Puerto La Paloma N° 449/11: 6.50—7.50 m].

Textularia sp. A.— X 191 [Chuy N° 364: 122.10—124.00 m].
Textularia sp. B. — X 125 [Puerto La Paloma N° 449/11: 7.50—8.00 m].
Reophax artica Brapy. — X 100 [Salinas N° 1034/1: 32—34 m].

Quinqueloculina cf. agglutinata Cusuman. — a, side view: X 115; b, apertural view:
X 100 [Chuy N° 364: 122.10—124.00 m].

: Quinqueloculina patagonica d’OrsıcnY. — X 100 [Chuy N° 364: 122.10—124.00 m].

8: Quingueloculina vulgaris d’OrBıcnY. — X 75 [Chuy N° 364: 122.10— 124.00 m].

: Quinqueloculina intricata TERQUEM. — X 38 [Puerto La Paloma N° 449/11: 7.50—

8.00 m].

: Quingueloculina sp. A. — X 170 [Chuy N° 364: 124.00—125.40 m].

: Quinqueloculina angulata (WıLLıamson), forma typica. — a, side view: X 98; b, detail

of apertural region: X 351 [Puerto La Paloma N° 449/11: 7.50—8.00 m].

: Quinqueloculina atlantica BoLTovskoY. — a, side view: X 85; b, apertural detail: X 351

[Puerto La Paloma N® 449/11: 7.50—8.00 m].

: Quinqueloculina af. frigida Parker. — a, side view: X 100; b, detail of apertural re-

gion: X 412 [Puerto La Paloma N° 449/11: 4.50—5.00 m].

: Quinqueloculina seminulum (LinNAEUs). — a, side view: X 65; b, apertural detail X 226

[Puerto La Paloma N°® 449/11: 7.50—8.00 m].

Zitteliana 4, 1978

SPRECHMANN, P.: Paleoecology and Paleogeography of the Uruguayan Coastal Area

tteliana 4, 1978

SPRECHMANN, P.: Paleoecology and Paleogeography of the Uruguayan Coasta

Fig. 1:
Fig. 2:
JArz, SB
Fig. 4:
Fig. 5:
Fig. 6:
Fig.

Fig.

Fig. 9:
Fig. 10:
Fig. 11
Fig. 12
Fig. 13:
Fig. 14:
Fig. 15:

Böllatte2

Quinqueloculina sp. B. — X 125 [Chuy N° 364: 124.00— 125.40 m].

Quinqueloculina sp. C. — a, side view: X 110; b, apertural view: X 226 [Chuy N° 364:
122.10— 124.00 m].

Quinqueloculina sp. D. — X 100 [Puerto La Paloma N° 449/11: 7.50—8.00 m].
Quinqueloculina sp. E.— X 130 [Puerto La Paloma N° 449/11: 7.50—8.00 m].

Flintinella sp. — a, side view: X 80; b, apertural detail: X 238 [Puerto La Paloma
N° 449/11: 7.50—8.00 m].

Massilina secans (d’OrBıcnY). — X 80 [Chuy N° 364: 122.10— 124.00 m].

Triloculina sp. — a, side view: X 160; b, apertural view: X 286 [San Jose de Carrasco

N° 442/1: 17—18 m].

Pyrgo nasuta CusHMAn. — X 115 [Chuy N° 364: 125.40— 128.00 m].

Pyrgo ringens patagonica (d’Orsıcny). — X 100 [Puerto La Paloma N° 449/11: 6.50 —
7.50 m].
Miliolinella subrotunda (Montagu). — X 120 [Puerto La Paloma N° 449/11: 7.50—
8.00 m].

: Dentalina communis d’Orsıcny. — a, side view: X 20; b, detail of apertural region:

X 135 [Puerto La Paloma N° 449/11: 7.50—8.00 m].

Lagena laevis (MonTaGu), forma perlucida (MontTAsu). — X 150 [Chuy N°® 364:
124.00— 125.40 m].

Lagena sp. — X 160 [Chuy N® 364: 122.10— 124.00 m].

Lenticulina rotulata (LAMARCK). — a, side view: X 140; b, edge view: X 175. — 14a and
14b are different specimens [Chuy N° 364: 122.10— 124.00 m].
Lenticulina limbosa (Reuss). — a, side view: X 326; b, detail of apertural region: X 653

[Salinas N° 1034/1: 32—34 m].

a va ww

Plate 3

Guttulina plancii d’OrBıGnY. — a, side view: X 110; b, apertural detail: X 224 [Puerto
La Paloma N°® 449/11: 5.00—6.50 m].

Guttulina problema d’Orsıcny. — a, side view: X 90; b, detail of apertural region:
X 226 [Costa Azul N® 1060/1: 19—21 m].

Oolina melo d’Orsıcny. — X 251 [Costa Azul N® 1060/1: 19—21 m].
Buliminella elegantissima (d’OrsıcnY). — X 201 [Salinas N° 1034/1: 32—34 m].
Bolivina striatula Cusuman. — X 140 [Chuy N° 364: 35—40 m].

Fissurina laevigata Reuss. — a, side view: X 201; b, apertural detail: X 362 [Salinas
N° 1034/1: 32—34 m].
Bolivina compacta SIDEBOTTOM. — X 251 [Lecocq: 1.20 m].

Bolivina cf. lomitensis GaLLowAaY & WıssLer. — X 191 [Lecocq: 1.00 m].
Bolivina cf. variabilis (WıLLıamson). — X 201 [Lecocq: 1.00 m].
Bulimina cf. affinis d’Orsıcny. — X 160 [Chuy N° 364: 45—50 m].

Discorbis peruvianus (d’OrBIGNY). — a, spiral view: X 145 [Costa Azul N® 1060/1:
19—21 m]; b, umbilical side: X 201 [Lecocq: 0.60 m].

Discorbis gr. vilardeboanus (d’Orsıcny). — a, spiral side: X 238 [Lecocq: 0.60 m]; b,
umbilical side: X 201 [Costa Azul N® 1060/1: 19—21 m].

Rotorbinella rosea (d’Orsıcny). — Test from three sides. a: X 201; b: X 201; c: X 226.
— 13b and 13c two views of same specimen [Chuy N°® 364: 122.10— 124.00 m].
Discorbis williamsoni (CHarman & PARR), forma praegeri HERON-ALLEN & EARLAND. —
a, spiral side: X 191; b, umbilical side: X 251. 14a and 14b are different specimens [Puer-
to La Paloma N° 449/11: 7.50—8.00 m].

Zitteliana 4, 1978

SPRECHMANN, P.: Paleoecology and Paleogeography of the Uruguayan Coastal

Zitteliana 4, 1$

SPRECHMANN, P.:

as
ug
[557

Fig. 7:

Fig. 8:
Fig. 9—10:

Plate 4

Discorbinella? bertheloti, forma boueana (d’OrsıcnY). — a, spiral side: X 191 [Chuy
N® 364: 125.40—128.00 m]; b, umbilical side: X 150 [Chuy N® 364: 122.10—
124.00 m].

Buccella peruviana (d’Orsıcny), s. I. — a: X 160 [Puerto La Paloma N°® 449/11:
7.50—8.00 m]; b: X 160 [Chuy N® 364: 122.10—124.00 m].

Cancris sagra (d’Orsıcny). — X 110 [Chuy N° 364: 124.00— 125.40 m].

Ammonia beccarii (LiNNAEUS) var. parkinsoniana (d’Orsıcny). — a, spiral side:
X 130; b, umbilical side: X 170. — 4a and 4b are different specimens [Rincön de la
Bolsa N® 754: 1.50—2.80 m].

Elphidium depressulum Cusuman. — X 150 [Chuy N® 364: 124.00—125.40 m].

Elphidium gr. excavatum (TERQUEM). — a, side view: X 130; b, apertural view: X 130
[Chuy N°® 364: 35 —40 m].

Elphidium discoidale (d’Orsıcny). — a, side view: X 130; b, apertural view: X 191
[Puerto La Paloma N° 449/11: 7.50—8.00 m].

Elphidium gunteri Core. — X 130 [San Luis N® 1072/1: 29—30 m].

Elphidium cf. discoidale (d’Orsıcny). — 9: X 130 [Rincön de la Bolsa N® 754:
1.50—2.80]; 10: X 145 [San Jose de Carrasco N® 442/1:17—18 m].

Fig.

1—2:
33:
a:
Ge
.16%
78:

9—12

Plate 5

Elphidium galvestonense KornreLd. — la, side view: X 150; 1b, appertural view,
aperture apparently closed: X 130 [Lecocq: 1.00 m]; 2a, side view: X 140; 2b, detail
of apertural region, showing slitlike interiomarginal aperture: X 301 [Lecocq: 0.70 m].

Elphidium aff. sagrum (d’Orsıcny). — X 135 [Chuy N® 364: 122.10—124.00 m].
Elphidium sp. A. — X 115 [Chuy N® 364: 122.10—124.00 m].

Elphidium sp. B. — X 251 [Chuy N® 364: 35—40 m].

Nonion tisburyensis BUTCHER. — X 181 [Salinas N® 1034/1: 32—34 m].

Elphidium cf. tuberculatum (d’Orsıcny). — 7: X 125 [Chuy N? 364: 122.10—
124.00 m]; 8a: X 120; 8b: X 110 [Chuy N° 364: 125.40— 128.00 m].

: Poroeponides lateralis (TERQUEM). — 9, spiral side: X 65; 10, umbilical side: X 50;

11: X 50; 12: X 43. — 9—12 are different specimens [Puerto La Paloma N°449/11:
7.50—8.00 m].

Zitteliana 4, 1978 Plate 5

SPRECHMANN, P.: Paleoecology and Paleogeography of the Uruguayan Coastal Area

ıtteliana 4, 1978 Plate 6

Fig.
Fig. 2
Big. 3
Fig.
Fig.
Fig.
Fig.
Fig.
Eie9
Fig. 10
Fig. 11
Fig. 12

SmNTESS UIEER

Plate 6

Ampbhistegina gibbosa d’Orsıcny. — X 60 [Chuy N° 364: 128.00—130.00 m].

Cibicides aknerianus (d’Orsıcny). — Test from three sides. a: X 160; b: X 160;
ce: X 140. — 2a and 2b two views of same specimen [Chuy N® 364: 122.10—124.00 m].
Cibicides “pseudoungerianus” (Cusmman). — a: ventral view: X 140; b: edge view:

X 145 [Chuy N® 364: 122.10— 124.00 m].

Fursenkoina sp. — X 160 [Chuy N° 364: 124.00—125.40 m].

Cassidulina curvata PnueGer & Parker. — X 201 [Chuy N° 364: 125.40—128.00 m].
Cassidulina laevigata d’OrsıcnY. — X 150 [Chuy N° 364: 122.10—124.00 m].
Cassidulina subglobosa Brapy. — X 251 [Chuy N°® 364: 122.10—124.00 m].

Nonionella atlantica Cusuman. — a, side view: X 140; b, edge view: X 130 [Chuy
N° 364: 122.10— 124.00 m].

Nonionella auricula HErON-ALLEN & EARLAND. — a, side view: X 85; b, edge view:
X 88 [Chuy N® 364: 125.40—128.00 m].

Nonion grateloupii (d’Orsıcny). — a, side view: X 145; b, edge view: X 150 [Chuy
N° 364: 124.00— 125.40 m].

Nonion sp. A. — a, side view: X 150; b, edge view: X 156 [Chuy N® 364:
122.10— 124.00 m].

Nonion sp. B. — a, side view: X 150; b, edge view: X 150 [Chuy N° 364: 128.00—
130.00 m].

Plate 7

Holotype specimen of Compsognathus longipes Wagner, 1861 (B. S. P. A. S. 1563).
The scale is 100 mm long.

Zitteliana 4, 1978 Plate 7

4
“|
|

X N rad
are

S >»
NR

“ &: s
ir a

OsSTROM, J. H.: The Osteology of Compsognathus longipes WAGNER.

Plate 8

Zitteliana 4, 1978

‚sn

Ostrom, J. H.: The Osteology of Compsognathus longipes WAGNER.

Plate 8

Skull of the holotype specimen of Compsognathus longipes. Scale divisions equal 1.0 mm.
For identification of the various skull bones and fragments, see Figure 1.

Fig.

Plate 9

Compsognathus longipes (B. S. P. A. S. 1563).

: Braincase, in ventral aspect. The occipital condyle is conspicuous at the right. The two-

pronged structure at the left represents the ventral margins of the cultriform process of the
parasphenoid. Scale units equal 1.0 mm.

: Rostral extremity of the left dentary to show the “bent” form of anterior teeth. Suc-

ceeding teeth are less “bent”, becoming uniformly curved. The horizontal line equals
5 mm.

: The disarticulated hands; left hand to the left and right manus to the right. Scale divi-

sions equal 1.0 mm.

: Example of the two different sized manual unguals preserved. On the left is an impres-

sion which is interpreted here as the ungual of digit I, left hand. That on the right includes
the bony ungual and parts of the horny sheath of digit II, right hand. Scale divisions
equal 1.0 mm.

:Bony ungual and parts of the horny claw (arrows) of digit II of the left manus. Com-

pare with the upper illustration of text figure 5. Scale divisions equal 1.0 mm.

Zitteliana 4, 1978 Piate 9

Ostrom, J.H.: The Osteology of Compsognathus longipes WAGNER.

Zitteliana 4, 1978 Plate 10

7 8 9, 10, "
TIÄTTTTeTTTEEEREREETETÄTTOTTÄEEREERERRREETCITETTTETEETETTET
x \ & : ae

€

OstroM, J. H.: The Osteology of Compsognathus longipes WAGNER.

Fig. 1:
Fig. 2:

Fig. 3:

Fig. 4:
Fig. 5:

Fig. 6:

Pillateze 100
Compsognathus longipes (B.S. P. A. S. 1563).

Right (uppermost) and left hind feet. Scale equals 100 mm.

Distal phalanges of digit III of the right pes. The penultimate phalanx appears to have
been rotated about its long axis and preserved up-side-down. Scale divisions at left equal
1.0 mm.

Two similar, isolated bones which are believed to be the left and right articulars. They
are preserved just above the left maxilla (see Figure 1 and Plate 7.). Scale units equal
1.0 mm.

Unidentified mystery bone. Scale units at left equal 1.0 mm.

The Humboldt specimen described by Dames (1884), that sometimes has been referred to
Compsognathus. These bones appear to represent (from left to right) metatarsals IV, II
and III, plus a solitary proximal phalanx. It is concluded here that this specimen is not
referrable to Compsognathus. Scale Units equal 1.0 mm.

Rare, minute crystals of quartz (arrows) occurring within calcite crystal-lined vug-like
cavities in the body region of Compsognathus. These are vidence of solution and secon-
dary erystallization. The vertical line equals 1.0 mm.

Plate 11

Compsognathus longipes (B.S.P. A.S.1563); so-called dermal armor and soft-tissue impressions.

ig. 1: The so-called impressions of “skin armor”, described by von Huene (1901). This is the

site (the depression just below the scapula) in which Huene saw “15 polygons” (arrows ?),
which he interpreted as evidence of bony skin plates. Scale divisions equal 1.0 mm.

:Nopsca (1903) interpreted these parallel striations (arrow) between the right radius and

ulna of Compsognathus as “muscle fibers”. Magnification, approximately 15 X.

: This “dimpled texture” was interpreted by Nopcsa (1903) as integument impressions, but

it seems much more likely to be a solution-etched surface. Magnification is approximately
1HX.

:Normal, un-etched surface of the Compsognathus slab, for comparison with the “skin

imprint” of Fig. 3. The curved line is a human hair, to provide scale. Magnification,
approximately 15 X.

Zitteliana 4, 1978 Plate 11

Ostrom, J.H.: The Osteology of Compsognathus longipes WAGNER.

Plate 12

Zitteliana 4, 1978

Osrron, J. H.: The Osteology of Compsognathus longipes WAGNER.

Plate 12

The Nice specimen of Compsognathus longipes. Originally, this specimen was assigned to a new
species, C. corallestris, by Bidar, Demay and Thomel (1972). It is here considered to be indistinct
from C. longipes.

Plate 13

The stomach contents preserved within the rib cage of the Munich specimen of Compsognathus
longipes — a small lizard skeleton. For identification of these remains, refer to Figures 8 and 9 in
the text. Scale is in mm.

Zitteliana 4, 1978 Plate 13

Ostrom, J. H.: The Osteology of Compsognathus longipes WAGNER.

Zitteliana 4, 1978 Plate 14

OsTroM, J. H.: The Osteology of Compsognathns longipes WAGNER.

Fig. 1:

Fig. 2:

Fig. 3:

Fig. 4:

Fig.5:

Fig. 6:

Plate 14
Bavarisaurus cf. macrodactylus.

Autotomous tail vertebrae of the “stomach contents”, for comparison with Fig. 2, at the
right. The arrows indicate the autotomy sutures. Scale divisions equal 1.0 mm.

Autotomous caudal vertebrae of the holotype specimen (B.S.P. 1873 III 501) of Bava-
risaurus macrodactylus. The arrows point to the autotomy sutures of three contiguous
vertebrae. Scale units equal 1.0 mm.

Isolated left lower jaw preserved outside of the body cavity of Compsognathus.
Presumably, it belongs to the small skeleton preserved within Compsognathus. Scale units
equal 1.0 mm.

The distal end of the left humerus (arrow) of the “consumed” little reptile. Compare
this with the humerus illustrated in Fig. 5, to the right. Scale units equal 1.0 mm.

The distal end of the left humerus of the holotype specimen (B.S.P. 1873 III 501) of
Bavarisaurus macrodactylus. Compare this with Fig. 4, to the left. The scale divisions
equal 1.0 mm.

The left pes of the holotype specimen of Bavarisaurus macrodactylus (B.S.P. 1873 III
501). Compare this with text Figure 10, the reconstructed foot of the “stomach contents”
of Compsognathus. The scale units at the right equal 1.0 mm.

Lithograph of the type specimen of Compsognathus longipes Wagner 1861, in the
Bayerische Staatssammlung für Paläontologie und historische Geologie in Munich. Coincidentally,
the stone from which this print was made, was discovered by the author in 1961 in the Vertebrate
Paleontology collections of the Peabody Museum of Natural History, Yale University, New
Haven, Connecticut. How and when this stone was obtained by Yale are not known, but it pro-
bably was acquired by ©. C. Marsh sometime after his visit to Munich in 1881. The art work
apparently was completed after 1882, because the right tarsal fragment described by Baur (1882)
is missing in the lithograph. The artist is unknown, but this work may be the “careful drawing
of the original made by Krapf in 1887” (Marsh, 1895, p. 409; 1896, p. 228) mentioned by Marsh
as part of the basis for his restoration of Compsognathus. "The print reproduced here was made
from the original stone by Heddi Seibel of the Yale University School of Art.

Zitteliana 4, 1978

OsTRroM, J. H.: The Osteology of Compsognathus longipes WAGNER.

70
783

Zitteliana

Abhandlungen der Bayerischen Staatssammlung für Paläontologie
und historische Geologie

Begründet von Prof. Dr. Richard Dehm

HECTOR A. LEANZA

The Lower and Middle Tithonian Ammonite Fauna

from Cerro Lotena, Province of Neuquen, Argentina

WILLIAM A. GLEMENS

Rhaeto-Liassie Mammals from Switzerland and West Germany

MÜNCHEN 1980

Herausgegeben von Prof. Dr. Dietrich Herm,
Bayerische Staatssammlung für Paläontologie
und historische Geologie München

Redaktion: Dr. Peter Wellnhofer
ISSN 0373 - 9627

Zitteliana

Abhandlungen der Bayerischen Staatssammlung für Paläontologie
und historische Geologie

Begründet von Prof. Dr. Richard Dehm

HECTOR A. LEANZA

The Lower and Middle Tithonian Ammonite Fauna

from Cerro Lotena, Province of Neuquen, Argentina

WILLIAM A. CLEMENS

Rhaeto-Liassie Mammals from Switzerland and West Germany

MÜNCHEN 1980

Gesamtherstellung: Druck- und Verlagsanstalt Gebr. Geiselberger, Altötting

The Lower and Middle Tithonian Ammonite Fauna
from Cerro Lotena, Province of Neuquen, Argentina.

HECTOR A. LEANZA*)

With 10 text figures and plates 1—9

ABSTRACT

The present monograph deals with the description
of the ammonite fauna from Cerro Lotena, located in
the south central part of the Neuquen province, Ar-
gentine Republic. The stratigraphic section investi-
gated occurs on the southern slope of Cerro Lotena.
In this section the following formations were distin-
guished in ascending order: the Vaca Muerta Forma-
tion (129 m), the Picün Leufü Formation (57 m) and
the Mulichinco Formation (101 m) pars. The entire
ammonite fauna described here is from the Vaca
Muerta Formation. The Picun Leufü Formation,
characterized by a coastal facies of bivalves contains
ammonites only sporadically. The Vaca Muerta For-
mation is attributed to the Lower and Middle Titho-
nian, the Picün Leufü Formation to the Upper Titho-
nian and the Mulichinco Formation to the Berriasian.

The fauna consists of 5 families, 16 genera, 30 spe-
cies and 2 subspecies. Of these, one genus, 6 species
and one subspecies are new, as follows: Choicensi-
sphinctes gen. nov., Glochiceras steneri n. sp., Hildo-
glochiceras wiedmanni n. sp., Parastreblites coma-
huensis n. sp., Subdichotomoceras arancanense n. SP.,

Pachysphinctes americanensis n. sp., Virgatosphinctes
evolutus n. sp. and Choicensisphinctes choicensis suti-
lisn.ssp. The genera Hildoglochiceras, Parastreblites,
Pachysphinctes and Parapallasiceras are cited for the
first time from the Andean Tithonian.

The fauna can be grouped in 4 associations that
basically correspond to ammonite zones previously
established by others authors, as follows: Virgato-
sphinctes mendozanus Zone, Pseudolissoceras zitteli
Zone, Aulacosphinctes proximus Zone and Windhau-
seniceras internispinosum Zone. Considering the tri-
partite division of the Tithonian adopted here, the
first zone corresponds to the uppermost Lower Titho-
nian and the remaining three to the Middle Tithonian.
The age and other features of these zones are consider-
ed, and suggestions are made toward improving their
definition.

The described fauna shows close affinities princi-
pally with those of Mexico, Madagascar and India,
and to a lesser extent with those of the Mediterranean
Realm. No true Boreal elements have been found.

KURZFASSUNG

Es wird die Ammonitenfauna des Cerro Lotena be-
schrieben, der im Süden des zentralen Teils der Pro-
vinz Neuquen (Argentinien) liegt. Das hier beschrie-
bene Profil ist am Südhang des Cerro Lotena aufge-
schlossen. Von unten nach oben werden folgende For-
mationen unterschieden: Vaca Muerta-Formation
(129 m), Picün Leufü-Formation (57 m) und Muli-
chinco-Formation (101 m) pars. Die hier beschriebene
Ammonitenfauna stammt aus der Vaca Muerta-For-
mation, die Unterem und Mittlerem Tithon entspricht.
Die dem Oberen Tithon entsprechende Picun Leufü-
Formation ist in Litoralfazies mit Bivalven und nur
sporadischen Ammoniten entwickelt. Die Mulichinco-
Formation entspricht dem Berrias.

Die hier beschriebene Fauna besteht aus 5 Familien,
16 Gattungen, 30 Arten und 2 Unterarten. Davon
sind 1 Gattung, 6 Arten und 1 Unterart neu, und zwar
Choicensisphinctes n. g., Glochiceras steneri n. sp.,
Hildoglochiceras wiedmanni n. sp., Parastreblites co-
mahuensis n. sp., Subdichotomoceras araucanense n.
sp., Pachysphinctes americanensis n. sp., Virgato-
sphinctes ecolutus n. sp. und Choicensisphinctes choi-
censis sutilis n. ssp. Die Gattungen Hildoglochiceras,

*) Secretaria de Mineria, Av. Santa Fe 1548, 1060 Capi-
tal Federal, Argentina. Temporarily at Institut und Museum
für Geologie und Paläontologie, Sigwartstr. 10, 7400 Tübin-
gen, West Germany.

Parastreblites, Pachysphinctes und Parapallasiceras
werden zum ersten Mal aus dem andinen Tithon be-

schrieben.

Die Fauna kann in vier Associationen gruppiert
werden, die im wesentlichen bereits bestehenden Am-
monitenzonen entsprechen. Es sind dies die Zone des
Virgatosphinctes mendozanus, die Zone des Pseudolis-
soceras zitteli, die Zone des Aulacosphinctes proximus
und die Zone des Windhauseniceras internispinosum.

Da hier der Dreigliederung des Tithon gefolgt wird,
entspricht die erstgenannte Zone dem höchsten Unter-
tithon, die drei übrigen Zonen dem Mitteltithon. Die
Zonengliederung wird ausführlich diskutiert.

In paläogeographischer Hinsicht zeigt die Fauna
enge Beziehungen zu Mexico, Madagascar und Indien,
dagegen geringere Verbindungen zur mediterranen
Faunenprovinz. Boreale Faunenelemente sind dem-
gegenüber nicht nachweisbar.

RESUMEN

La presente monografia trata acera de la descrip-
cıön de la fauna de ammonites del Cerro Lotena,
situado en la parte sud central de la provincia del
Neuquen, Repüblica Argentina. Se ofrece la sec-
ciön estratigräfica levantada en el faldeo sur del
Cerro Lotena, donde se distinguen en orden ascendente
las Formaciones Vaca Muerta (129 m), Picun Leufü
(57 m) y Mulichinco (101 m) pars. La totalidad de la
fauna de ammonites estudiada procede de la Forma-
ciön Vaca Muerta. La Formaciön Picun Leufü,
caracterizada por una facies costera de bivalvos, posee
ammonites sölo muy esporädicamente. Segün los
resultados alcanzados, la Formaciön Vaca Muerta se
atribuye al Tithoniano inferior y medio, la Formaciön
Picun Leufü al Tithoniano superior y la Formaciön
Mulichinco al Berriasiano.

El estudio de la fauna permitiö individualizar
5 familias, 16 generos, 30 especies y 2 subespecies. De
ellos, un genero, 6 especies y una subespecie son
nuevos, a saber: Choicensisphinctes gen. nov., Glochi-
ceras steueri n. sp., Hildoglochiceras wiedmanni n. sp.,
Parastreblites comahuensis n. sp., Subdichotomoceras
araucanense n. sp., Pachysphinctes americanensis n.

sp., Virgatosphinctes evolutus n. sp. y Choicensis-
phinctes choicensis sutilis n. ssp. Los generos Hildo-
glochiceras, Parastreblites, Pachysphinctes y Para-
pallasiceras se citan por primera vez en el Tithoniano
andino.

La fauna estudiada puede agruparse en 4 asociacio-
nes que bäsicamente responden a zonas de ammonites
previamente establecidas por otros autores, a saber:
Zona de Virgatosphinctes mendozanus, Zona de Pseu-
dolissoceras zitteli, Zona de Aulacosphinctes proximus
y Zona de Windhauseniceras internispinosum. Segün
la divisiön tripartita del Tithoniano aqui adoptada,
la primera zona corresponde al mäs alto Tithoniano
inferior, mientras que las tres restantes indican el
Tithoniano medio. Se efectuan consideraciones y
aportes que permiten ampliar el conocimiento de cada
una de ellas, asi como precisar su edad con mayor
exactitud.

La fauna descripta presenta estrechas afınidades

Bet 3 i
principalmente con aquellas de Mexico, Madagascar
e India y, en menor grado, con aquellas del dominio
mediterräneo. No se hallaron elementos boreales en
la fauna estudiada.

TABLE-OFGONTENTS
I. INTRODUCTION 6
Acknowledgements 6
II. PREVIOUS WORK 6
III. STRATIGRAPHY ; 7
Description of the Cerro Tötena. section . 8
IV. ANALYSIS OF THE FAUNA 9
Preservation of the ammonite fauna 12
V. TAXONOMIC REVISION er ee na ie ee en
VI. THE AMMONITES ZONES AND CORRELATIONS N SE EEE 13
The Virgatosphinctes mendozanus Zone 13
The Pseudolissoceras zitteli Zone 15
The Aulacosphinctes proximus Zone 15
The Windhauseniceras internispinosum Zone 15
VII. SYSTEMATIC DESCRIPTIONS 17
Measurements and abreviations . 17
Repositories 17

Order AMMONOIDEA Zırrer, 1884

Suborder AMMONITINA Hyatt, 1889 . . .
Superfamily HAPLOCERATACEAE ZITTEL, 1884
Family HAPLOCERATIDAE Zitter, 1884

Genus PSEUDOLISSOCERAS SrarH, 1925
Pseudolissoceras zitteli (BURCKHARDT, 1903)
Pseudolissoceras pseudooolithicum (HaurT, 1907)
Genus GLOCHICERAS HyArTT, 1900
Glochiceras steueri n. sp. - :
Genus HILDOGLOCHICERAS SpatH, 1924 ö
Hildoglochiceras wiedmanni n. sp.

Family OPPELIIDAE BoNnARELLI, 1884

Subfamily TARAMELLICERATINAE Srarn, 1928
Genus PARASTREBLITES DonzE & Enax, 1961
Parastreblites comahuensis n. sp.

Superfamily PERISPHINCTACEAE STEINMANN, 1880
Family PERISPHINCTIDAE STEınmann, 1890

Subfamily VIRGATOSPHINCTINAE SpaTH, 1925

Genus PSEUDINVOLUTICERAS SPpaTH, 1925
Pseudinvoluticeras douvillei SpaTH, 1925
Pseudinvoluticeras windhauseni (WEAVER, 1931)
Pseudinvoluticeras (?) wilfridi (Douv., 1910)

Genus VIRGATOSPHINCTES Unuic, 1910
Virgatosphinctes mexicanus (BURCKHARDT, 1906)
Virgatosphinctes andesensis (DouviLı£, 1910) .
Virgatosphinctes burckhardti (Douvıu£, 1910)
Virgatosphinctes denseplicatus rotundus SPATH, 19271933
Virgatosphinctes evolutus n.sp. . -

Genus CHOICENSISPHINCTES nov.

Choicensisphinctes choicensis (BURCKHARDT, 1903)
Choicensisphinctes choicensis sutilis n. ssp.
Choicensisphinctes erinoides (BURCKHARDT, 1903).

Genus AULACOSPHINCTOIDES SPATH, 1923 . .
Aulacosphinctoides aff. A. hundesianus (Uni, I
Aulacosphinctoides sp. indet. . :

Genus SUBDICHOTOMOCERAS Sparn, 1925
Subdichotomoceras windhauseni (WEAVER, 1931) .
Subdichotomoceras araucanense n. sp.

Subdichotomoceras sp. juv.indet. . .

Genus PARAPALLASICERAS SPpATH, 1925 :
Parapallasiceras aff. P. pseudocolubrinoides OLorız, 1978 R
Parapallasiceras aff. P. recticosta OLorız, 1978
Parapallasiceras sp. indet. .

Genus PACHYSPHINCTES Dierrich, 1925
Pachysphinctes americanensis n. sp.

Family ASPIDOCERATIDAE Zırter, 1895 .

Subfamily ASPIDOCERATINAE Zırter, 1895 .
Genus ASPIDOCERAS Zıtteı, 1895
Aspidoceras enomphalum STEUER, 1897

Family BERRIASELLIDAE SrATH, 1922

Subfamily HIMALAYITINAE SratH, 1923

Genus WINDHAUSENICERAS Lranza, 1945
Windhauseniceras internispinosum (KrANTz, 1926)
Genus HEMISPITICERAS SpartH, 1925
Hemispiticeras aff. H. steinmanni (STEUER, 1897) .
Genus AULACOSPHINCTES Uhrıc, 1910
Aulacosphinctes proximus (STEUER, 1897)

Genus CORONGOCERAS SPpATH, 1925
Corongoceras lotenoense SpATH, 1925

VIII. LITERATURE CITED

I. INTRODUCTION

The description of the ammonite fauna from Cerro
Lotena, which is the basis of this monograph, was
necessary in order to advance our knowledge of the
Andean Tithonian. Although important progress
related to the Upper Jurassic and Lower Cretaceous
was made by A. F. Leanza (1945), who described the
ammonite fauna from Sierra Azul, the Lower and
Middle Tithonian faunas have not been sufficiently
investigated. The Sierra Azul was a topographically
elevated area during most of the Jurassic period and,
therefore, the Tithonian transgression begins in this
area with the Windhauseniceras internispinosum Zo-
ne, which is poorly documented and contains only
Wichmanniceras mirum in association with the index
species. Above this zone the ammonites become
abundant up to the late Valanginian, including the
transition from the Jurassic to the Cretaceous.

Knowledge concerning the Lower and Middle Ti-
thonian, however, has not appreciably improved since
the classic monographs of BURCKHARDT (1900a, 1900b,
1903), Haurt (1907), Krantz (1926, 1928) and
WEAVER (1931). The work of Inpans (1954), al-
though referred to the Lower Tithonian, deals exclusi-
vely with the Virgatosphinctinae Beds at the base of
the Tithonian transgression in southern Mendoza, and
therefore does not allow zonation of the Tithonian.

As anticipated by GROEBER (in A. F. LEAnzA, 1945,
p. 85), knowledge of the Andean Tithonian could be
improved by the study of the Cerro Lotena fauna.
Since this fauna extends downwards from the W. in-
ternispinosum Zone, it provides important informa-
tion on the earlier part of the Tithonian.

The collection of ammonites described here was
made by Dr. Anselmo WInDHAUSEN during the summer
of 1912. It was archieved in the repository of the
Museo de la Secretaria de Mineria of the Argentine
Republic. Part of this collection was temporarily
sent to Tübingen in order to carry out the present
study. The specimens were numbered according to
the outlines of the stratigraphic section made by
WINDHAUSEN (1914, table VIII), and they were sub-
divided in correspondence with WINDHAUSEN’s pro-
files I to III, which he later respectively identified as

“Kimmeridge-Portland”, “Lower Tithonian” and

“Upper Tithonian”.

The death of A. F. LeanzA in 1975 prevented his
intended description of the WInDHAusEn collection.
The present author, however, has had several oppor-
tunities, beginning in 1970, to visit the Cerro Lotena
area in association with a phosphate exploration pro-
gramme carried out by the Secretaria de Mineria of
the Argentine Republic. As a result, revision of
WINDHAUSEN’s section and relocation of his collected
samples has been carried out.

A visitor to the Cerro Lotena area today will surely
not find specimens of quality comparable to those
figured here from the WInDHAUSEn collection. The
fact that this area is relatively accessible, and close to
oil fields and kaolin and bentonite mines, has led to
invasions of tourists and collectors who over the years
have removed a large amount of scientifically valuable
material.

Acknowledgements

The Alexander von HumeoLpr Foundation sup-
ported this study through a research fellowship which
was held at the Institut und Museum für Geologie und
Paläontologie der Universität Tübingen, West Ger-
many. Publication of this work has also been made
possible by the Alexander von HumsoLpr Foundation.
The Secretaria de Minerla of the Argentine Republic
authorized the tenure of the fellowship in Germany.
To these institutions and the Alexander von Hum-
BoLDT Foundation I am highly indebted.

I am particularly grateful to Prof. Dr. Jost WIED-
MANN, who acted as academic supervisor and coordi-
nator, for his kind assistance and stimulating discus-
sions during my stay in Tübingen. Special thanks are
due to Dr. Peter SpRECHMAnN for valuable help and
critiscism, and to Dr. T. J. BARRETT, who improved the
English text. The photographs of this monograph
were made with the expert help of Mr. W. WETZEL
(Tübingen), and the illustrations were prepared by
K. MICHAEL.

This monograph is dedicated to the memory of my
father, Prof. Dr. Armando F. LEANZA.

IPPREVIOUS WORK

In the year 1907, Oscar Haurr described a fossil
assemblage composed of cephalopods, pelecypods,
brachiopods, echinoderms, worms and fishes from Cer-
ro Lotena. The material on which HaupTr based his
study was collected by Gustav STEINMANN during his
study trip to the Andes in the years 1902 and 1903.
A few years later, R. Dovvırı£ (1910) published the

results of his paleontological investigations on cepha-
lopods collected by M. Recope. Though Douviuı£
(1910, p. 5) stated that the fossils came from a region
between the Agrio river and the Picun Leufü creek,
it is Jikely that most of them are from the Cerro Lote-
na area since at this time REcopE was working as
inspector at the oil concession at Cerro Lotena.

The ammonites studied by Haurt and DouviLLE
became rapidly known in the scientific world because
the latter author favoured the presence of Boreal ele-
ments in this region of the Andes. This was just at the
time when the legendary discussion between the great
ammonitologists Charles BuRCKHARDT (1911a, 19115)
and Victor Unic (1910, 1911a, 1911b) regarding the
presence or absence of ammonites with Boreal aftini-
ties in the Andean domain, reached its most intense
point.

It was at this time, with an interest in both the pre-
sence of oil and the supposed presence of Boreal am-
monite faunas in this region, that WINDHAUSEN visited
Cerro Lotena in 1912. There, with the help of
A. FLossporr, he collected the ammonites described in
this monograph. Two years later, WınpHAUSEN (1914)
gave a summary of his results, illustrating for the first
time and with particular detail the Cerro Lotena sec-
tion.

New geological descriptions of the area were later
made, as a result of its petroliferous potential by
J. Keine (1925). One year later F. Krantz (1926)
published an important paper on Middle and Upper

Tithonian ammonites, describing some species from
Cerro Lotena. A translation of this work into Spa-
nish appeared two years later (F. Krantz, 1928).
Ch. WEAvER (1931) also presented very important
biostratigraphical data for the Cerro Lotena, in-
cluding its stratigraphical section.

Regional mapping of the area was carried out by
T. Suero (1942, 1951), who mapped the Hoja 36c,
Cerro Lotena, at a 1:200 000 scale.

More recently, detailed studies of the stratigraphy
of this area have been made (H. Leanza, 1973;
H. Leanza, H. MarcHsseE & )J. C. Rıccı, 1977;
H. Leanza & C. Huco, 1977). Z. GasPparınNI &
D. Derrare (1976) also have presented stratigraphic
data relating to the occurrence of fossil crocodiles in
the Vaca Muerta Formation.

It is also important to mention the classic mono-
graphs of ©. BEHRENDSEN (1891—1892; 1922, transl.),
A.STEUER (1897; 1921, transl.), H. GERTH (1925, 1926),
A.F.Leanza (1945) and J. Inpans (1954), in which a
great number of cephalopods were described from the
Neuquen and Mendoza basin; these are directly or
indirectly related to the fauna described here.

INFSERAITIGRABEIY

The Cerro Lotena is located 70 km south east of
Zapala, in the southern part of the Neuqu£n province,
Argentina (see Fig. 1).

The stratigraphic section described below was
measured on the southern slope of Cerro Lotena, and

Campanian-
Santonian

consists of the following Formations: Vaca Muerta
(WEAVER, 1931, emend. H. Leanza, 1972, 1973),
Picün Leufü (H. Leanza, 1973) and Mulichinco
(WEAVER, 1931). All these Formations constitute part
of the Mendoza Group. The stratigraphy of the area
can be summarized as follows:

Neuquen Group pars

Candeleros Formation

Unconformity

Lower Berriasian
Upper Tithonian

Middle Tithonian
Lower Tithonian

Picün Leufü Formation

Mulichinco Formation

Mendoza Group pars

Vaca Muerta Formation

Unconformity

Calovian

The ammonite faunas studied in this monograph
are entirely from the Vaca Muerta Formation. The
beds of this formation strike nearly east-west and dip
about 20° to the south, a value which decreases
slightly upsection. The Vaca Muerta Formation rests
unconformably upon the Lotena Formation by means
of a basal conglomerate termed the Quebrada del Sapo

Lotena Formation

Formation by some authors (cf. DIGREGORIO, 1972),
and is conformably overlain by the Picun Leufü For-
mation, which is characterized by a coastal facies of
bivalves. Ammonites are rare in this latter formation
but sufficient to postulate an Upper Tithonian age
(cf. H. LEanza & C. Huco, 1977, p. 253).

\NEUQUEN
j

Figure 1:

Description ofthe
Cerro Lotena Section

The lithological characteristics of the sediments of
the stratigraphic section, as well as its paleontological
contents, are as follow (from top to base):

Top: base of the Mulichinco Formation

Picün Leufü Formation H. LEAnzA, 1973. Total
thickness: 57 m
Bed 36: 0.80 m fine grained calcarenite, yellowish

white, hard.

Bed 35: 4.20 m brownish calcarenite, with Pholado-
mya gigantea Sow., Lucina leufuensis WEAv. and
Panope dupiniana d’Or».

Bed 34: 4.00 m fine grained calcarenite, yellowish. At
the base are quartz geodes In the more calcareous
portion are Myoconcha transatlantica BuRcK. and
Lucina leufuensis WEAVv.

Bed 33: 2.00 m fine banded calcareous sandstone,
yellowish brown.

Bed 32: 2.00 m yellowish white coquina, with Lucina
neuquensis Haupt, Pholadomya gigantea Sow. and
Panope dupiniana d’Ore.

Co. Sdsa

Co. Piedra Parada

Sketch map of the Cerro Lotena area.

Bed 31: 5.00 m fine
brownish, fissile.

grained calcareous sandstone,

Bed 30: 0.70 m yellowish white coquina, with Phola-
domya gigantea Sow., Lucina leufuensis WEav. and
Panope sp.

Bed 29: 6.30 m fine grained calcarenite, brownish.

Bed 28: 0.80 m yellowish white coquina, with Ostrea
minos CogQ., Panope dupiniana d’OrsB. and Lucina
leufuensis WEAV.

Bed 27: 7.20 m dark green shales.

Bed 26: 8.00 m yellowish white coquina, which consti-
tutes an excellent guide horizon. Ostrea minos
Coa., Ostrea lotenoensis WEAv., Megatrigonia exi-
mia (Phır.), Panope dupiniana d’Ors. and Sub-
steneroceras sp. indet.

Bed 25: 14.00 mfine grained calcareous sandststone,
fissile, with some aragonitic horizons. Ostrea lote-
noensis WEav., Exogyra couloni (DErR.) d’OrB. and
Lucina neuquensis HAUPT.

Bed 24: 2.00 m brownish coquina, with Exogyra cou-
loni (Der) d’OrB. sp. juv., Lucina nenquensis
Haupr and Serpula sp.

Vaca Muerta Formation WEAVvER, 1931, emend.

H. Leanza, 1972. Total thickness: 129 m.

Bed 23: 25.00 m dark olive-green shales, with some
bentonitic levels. Ostrea lotenoensis WEav. and
Serpula antiquata Sow.

Bed 22: 0.40 m pinkish-gray limestone, with Wind-
hauseniceras internispinosum (Krantz) and Pachy-
sphinctes americanensis n. sp.

Bed 21: 1.60 m olive-green and dark gray marls.

Bed 20: 0.20 m pinkish-gray massive limestone, with
Hemispiticeras aft. A. steinmanni (STEUER).

Bed 19: 0.80 m dark olive-green marls.

Bed 18: 0.50 m pinkish-gray massive limestone, with
Parapallasiceras sp. indet.

Bed 17: 4.00 m olive-green marls and shales.

Bed 16: 0.30 m yellowish-white limestone,
with Subdichotomoceras (WEAV.),
W. internispinosum (KRANTz), Corongoceras lote-
noense SpaTH and Parapallasiceras aff. P. pseudoco-
lubrinoides OLorız.

Bed 15: 3.20 m yellowish-green marls.

Bed 14: 0.40 m yellowish-grey massive limestone, with
W. internispinosum (Krantz) and Aulacosphinctoi-
des aff. A. hundesianus (UHLic).

Bed 13: 3.00 m yellowish-grey marls.

Bed 12: 0.80 m yellowish-grey massive limestone, with
Subdichotomoceras araucanense n. sp. and Aulaco-
sphinctoides sp. indet.

Bed 11: 2.00 m yellowish-brown marls.

Bed 10: 0.80 m greyish-white limestone, with Parapal-
lasiceras afl. recticosta OLorız, and A. euomphalum
STEUER.

Bed 9: 4.00 m dark brownish-grey shales. W. internis-
pinosum

Bed 8: 10.00 m greenish marls and shales.

Bed 7: 21.00 mgreenish and dark brownish shales,

massıve
windhauseni

with many nodules and calcareous concretions.
Abundant Anulacosphinctes proximus (STEUER) and
Laevaptychus crassissimus (HaurT), and rare Sub-
dichotomoceras sp. juv. indet.

Bed 6: 10.00 m dark brown shales, with Pseudolisso-
ceras zitteli (Burck.) and P. psendooolithicum
(Haupr). Remains of fish scales and /chthyosaurus
bones.

Bed 5:0.70 m dark grey limestone, with some quartz
veins. P. zitteli (Burck.) and Parastreblites coma-
huensis n. sp.

Bed 4: 14.30 m dark brown shales, with ?.
(BuRcK.).

Bed 3: 1.00 m grey brownish limestone with ?. zitteli
(Burck.) and rare Glochiceras steneri n. sp. and
Hildoglochiceras wiedmanni n. sp.

Bed 2: 25.00 m brown, yellowish-brown and dark
green bituminous shales (Virgatosphinctinae Beds).
At the top are remains of Geosaurus araucanensis
(Crocodilia). Ammonites: Psendinvoluticeras don-
villei SPATH, P. windhauseni (WEav.), P. (2) wilfridi
(Douv.), Virgatosphinctes andesensis (Douv.), V.
mexicanus (BuRcK.), V. burckhardti (Douv.), V. den-
seplicatus rotundus SPATH, V. evolutus n. sp., Choi-
censisphinctes choicensis (BURCK.), Ch. choicensis su-
tilisn. ssp. and Ch. erinoides (BuRcK.).

Bed 1:0.50m to5.00 m basal conglomerate with
rounded clasts of quartz, porphirites and pre-Titho-
nian sedimentary rocks, up to 4 cm of diameter.
Several strongly eroded Virgatosphinctinae frag-
ments also present. The conglomerate constitutes
the Quebrada del Sapo Formation of some authors
(cf. DIGREGoRIDO, 1972).

zitteli

Unconformity

Base: Lotena Formation WEAVER, 1931, Calovian.

IV. ANALYSIS OF THE FAUNA

The Cerro Lotena ammonite fauna described here
comprises 156 specimens, which are distributed
amongst 5 families, 16 genera, 30 species and 2 sub-
species. Of these, one genus, 6 species and one sub-
species are new. The family Perisphinctidae constitu-
tes 66 %/o of the fauna, followed by the families Ber-
riasellidae and Haploceratidae with 13 0/0 each. The
remaining 8 %/o is represented by the families Oppeli-
idae and Aspidoceratitidae. The systematic descrip-
tions follow the order proposed by ArKELL et al. (1957)
in the Treatise of Invertebrate Paleontology.

The family Haploceratidae is represented by the
genera Psendolissoceras, Glochiceras and Hildoglochi-
ceras. The genus Pseudolissoceras is very important

because it is a cosmopolitan form, known not only

from the Andean Tithonian of South America
(BURCKHARDT, 1903; Haupt, 1907; KranTz, 1926,
1928; WEAVER, 1931), Cuba (Imtav, 1942) and Me-
xico (BURCKHARDT, 1906; VERMA & WESTERMANN,
1973), but also in such distant regions as Tunisia
(ArnouLD-SAGET, 1951, 1951a), Iraq (SpAaTH, 1950),
Spain (Ororız, 1978), southeast France (DonzE &
Enav, 1961), south Germany (BARTHEL, 1962), the
Carpathians (ZırreL, 1870), Rumania (AvRAm, 1976)
and Italy (fde Enav, 1972). In Cerro Lotena 2 spe-
cies of this genus were found and identified as P. zit-
teli (Burck.) and P. psendooolithicum (Haupt). The
first species is particularly abundant, and gives the
name to the ?P. zitteli Zone, which belongs to the
Lower or Middle Tithonian depending on whether
the bi- or tripartite division of the Tithonian is used.

The genus Glochiceras is abundant in the European
White Jura (cf. ZıegLer, 1958) and has also been
reported from the Tithonian and/or Kimmeridigian
of Mexico (CAsTIıLLoO & AGUILERA, 1895; BURCKHARDT,
1906; Imray, 1939) and Argentina (KrANTZ, 1926,
1928; STEUER, 1897, 1921) as well as from Russia
(Zonov, 1937), Madagascar (CoLLiGnon, 1960), So-
maliland (SpatH, 1925), Tanganyika (DiETricH, 1933),
Iraq (SPATH, 1950), India (Sparu, 1927—33), Ru-
mania (Avram, 1976) and Japan (YokovYAaMma, 1904,
revised by Arkeıı, 1956). The species from Cerro
Lotena is new and is named G. stezxeri n. sp., with
Oppelia nimbata STEUER (non OPrEL) as the type
species. It was found in strata belonging to the
P. zitteli Zone.

The genus Hildoglochiceras also has a world wide
distribution, and is known from beds of generally
Lower Tithonian age from the Himalayas (Unuiıc,
1903—10), India (Srarun, 1927—33), Tanganyika
(ZwIErzyckı, 1914), Madagascar (CoLLiGnon, 1960),
Mexico (ImLAy, 1939) and Cuba (Imzay, 1942). The
only species found in Cerro Lotena is new and is
named H. wiedmanni n. sp.. It also belongs to the
P. zitteli Zone.

The family Oppeliidae is represented by a new
species of the genus Parastreblites, which was original-
ly described as a subgenus of Taramelliceras from
Lower Tithonian beds at Saint Concors, southeast
France (DonzeE & Enay, 1961). The species from
Cerro Lotena is closely related to ?P. waageni (Opper),
formerly included by SparH (1925) in Neochetoceras,
and is named P. comahuensis n. sp.

The family Perisphinctidae constitutes 66 %/o of the
studied fauna, but most of its representatives belong to
the subfamily Virgatosphinctinae, with the following
genera present: Subdichotomoceras, Pachysphinctes,
Aulacosphinctoides, Parapallasiceras, Virgatosphinc-
tes, Psendinvoluticeras and Choicensisphinctes gen.
nov.

The genus Subdichotomoceras, which can only be
distinguished from Pavlovia by the less densely-ribbed
internal whorls, is represented in Cerro Lotena, by
three species, one of them new: S$. windhauseni
(WEAVv.), S. arancanense n. sp., and S$. sp. juv. indet.
This genus has also been recorded in England (Spatn,
1925), Spain (Ororız, 1978), Somaliland (SpATH,
1925), Kenya (SrarH, 1930), Tanganyika (DIETRICH,
1933), Madagascar (CoLLıcnon, 1960), India (SpATH,
1927—33), Greenland ? (SparH, 1936) and Mexico
(VERMA & WESTERMANN, 1973). "The Cerro Lotena
specimens occur in the A. proximus and W. interni-
spinosum Zones of the Middle Tithonian. 'Though the
presence of Subdichotomoceras is known in Argentina,
the specimens illustrated here are the first to be origi-
nally described under this name.

The genus Pachysphinctes is reported here for the

first time from the Andes of South America, under the
name of P. americanensis n. sp. This genus is a com-
mon form in the Middle Katrol Beds of Cutch, India,
where its occurs in association with Subdichotomoceras
(cf. Sparn, 1927—33). The same association is also
present in the Tendaguru Group in the east of Africa
(cf. SpatH, 1930; DIETRICH, 1925, 1933), and in south-
ern Spain (Ororız, 1978). In Cerro Lotena it also
occurs in association with Subdichotomoceras, in the
W. internispinosum Zone.

The genus Aulacosphinctoides is represented in
Cerro Lotena by a form very similar to A. hundesia-
nus (UHLig) from the Spiti Shales, and by another
form whose poor preservation prevents specific classi-
fication. Aulacosphinctoides is another typical Ti-
thonian genus of world wide distribution, very com-
mon in New Zealand (SpaTH, 1923; STEVENS, 1968),
the Himalayas (UHntic, 1903—10), India (Spar,
1927—33), Somaliland (SrarH, 1925), Japan (cf.
Arkeıı, 1956) and Mexico (VERMA & WESTERMANN,
1973). In Argentina, its presence was suggested by
Arkeır (1956, p. 583) on the basis of examination of
the ammonite fauna illustrated by Inpans (1954) from
south Mendoza; however the forms described here are
the first from Argentina originally referred to by this
name.

Within the genus Parapallasiceras, typical of the
Lower and Middle Tithonian (cf. Zeıss, 1968), three
species have been distinguished: ?. aff. P. psendocolu-
brinoides OLorız, P. aff. P. recticosta OLorız, and
P. sp. indet. All three species are from the W. inter-
nispinosum Zone at Cerro Lotena.

The genus Virgatosphinctes has a world wide
distribution and is known from Europe (cf. ARKELL,
1956), north Africa (Roman, 1936), Somaliland
(Sparn, 1925), Abyssinia (Crıck, 1897, revised by
SpATH, 1925), Tanganyika (Arkeıı, 1956), Madagascar
(CoLLiGnon, 1960; BESAIRIE, 1936; LEMOINE, 1911),
Persia (Carr, 1940), Cutch (SpatH, 1927—33), Ba-
luchistan (Arkeıı, 1956), the Himalayas (UnHric, 1903
bis 1910), Pakistan (Farmı, 1972), Australia (BRUNN-
SCHWEILER, 1954), Mexico (ImLAY, 1939; VERMA &
WESTERMANN, 1973), Cuba (Imtay, 1942), Trinidad
(HurcHinson, 1938), Chile (CorvaLAn & PEREZ,
1958) and Argentina (WEAVvER, 1931; Inpans, 1954).
This genus is common in the Lower Tithonian as well
as in the Upper Tithonian. Though the presence of
Virgatosphinctes in the Andean domain has been
questioned in some cases, it is well documented from
the Cerro Lotena section, and is represented by the
following species: V. andesensis (Douv.), V. mexica-
nus (Burck.), V. denseplicatus rotundus SPATH,
V. burckhardti (Douv.),and V. evolutus n. sp.

The genus Pseudinvoluticeras, typical of the Lower
Tithonian, has been reported from Somaliland
(SpaTH, 1925), Madagascar (CorLicnon, 1960), Ana-

tolia (ide Enay, 1972), Mexico (VERMA & WESTER-
MANN, 1973) and Argentina (SpaTH, 1925, 1950). In
Cerro Lotena two, or possibly three species, have been
found, named P. douvillei Spatn, P. windhauseni
(Weav.), and P. (?) wilfridi (Douv.). The identifi-
cation of this last species is questionable because it is
based on internal whorls of a single specimen which
could also belong to Aulacosphinctoides. P. “decipiens”
SPATH is considered synonymous with the first species.

The genus Choicensisphinctes is here proposed in
order to group together certain ammonites having
inflated shells of olcostephanid aspect, and ornamen-
tation composed of fascicules with 4 to 10 ribs.

These ammonites constitute a homogeneous stock
which includes the following species of BURCKHARDT:
“P.” choicensis (type species), “P.” erinoides and
possibly “P.” aff. erinus. The proposal of this genus
follows the original suggestion by UHrtig (1911a,
p. 542) that these species could belong to a particular
group of ammonites. It should be noted that
Ch. choicensis is the most common species in the basal
beds of the Vaca Muerta Formation within the
Neuquen and Mendoza basin, and has been found
by the author, in addition to Cerro Lotena, at Mallın
de los Caballos, Mallin Quemado, Cajön de Almaza
and Bardas Blancas (cf. H. Leanza & C. Huco,
1977). Virgatosphinctes cf. raja InDAns (non UHLIG)
is included in the synonymic list of Ch. choicensis.
In Cerro Lotena the genus Choicensisphinctes is
represented by two species and one subspecies, as
follows: Ch. choicensis, Ch. choicensis sutilis n. ssp.
and Ch. erinoides. These species are common in the
V. mendozanus Zone at the base of the Tithonian
transgression.

Finally, it should be remarked that the genus Tor-
quatisphinctes, although it is not represented in the
fauna described here, it has been found by the author
at Cerro Lotena in the mandibles of a crocodile —
Geosaurus araucanensis — (cf. GAsPARINI & DELLAPE,
1976) in the lower part of the Vaca Muerta Forma-
tion, as well as in other parts of the Neuquen and
Mendoza basin (cf. H. LEanza & C. Huco, 1977).

The genera Virgatosphinctes, Pseudinvoluticeras
and Choicensisphinctes, as well as Torguatisphinctes,
occur together at the base of the Vaca Muerta Forma-
tion, within the V. mendozanus Zone (= Virgato-
sphinctinae Beds).

The family Aspidoceratidae is represented by only
one genus and one species: Aspidoceras euomphalum
STEUER. In the Cerro Lotena area, however, A. haupti
KranTz (1926) and A. neuguensis WEAVER (1931) as
well as A. steinmanni HaupT, the type species of the
genus Pseudhimalayites SpatH (1925) have also been
reported. The genus Aspidoceras is very cosmopoli-
tan and is common in sediments of Tithonian age.

The family Berriasellidae is represented exclusively

in the described fauna by the subfamily Himalayi-
tinae, containing the genera Windhauseniceras, Hemi-
spiticeras, Aulacosphinctes and Corongoceras.

The genus Windhauseniceras, which is apparently
endemic, is very well represented by its type species
W. internispinosum. This species is very abundant
and next to P. zitteli, is the commonest form in Cerro
Lotena. It gives the name to the W. internispinosum
Zone, which in this monograph is placed in the upper
part of the Middle Tithonian.

The genus Hemispiticeras is represented by a single
specimen that closely resembles its type species
“R.” steinmanni STEUER, differing only by having a
less obvious lateroventral row of tubercules. It is
therefore regarded as H. aff. H. steinmanni (STEUER).

The genus Aulacosphinctes is well represented in
Cerro Lotena by a single species identified as A. pro-
ximus (STEUER). This typical Tithonian genus is
known from Algeria (Roman, 1936), Somaliland
(SPATH, 1925), Abyssinia (Crıck, 1897, revised by
SPATH, 1925), Madagascar (CorLıcnon, 1960), Cutch
(SPATH, 1927—33), the Himalayas (UnLic, 1903— 10),
Pakistan (Farmı, 1972), California ? (ImLav, 1952),
Argentina (STEUER, 1897, 1921; WEAvER, 1931;
A. F. LEeanza, 1945; Inpans, 1954) and in Chile
(CorvarAn, 1959). The described species is parti-
cularly abundant in the Cerro Lotena section in the
beds occurring between the P. zitteli and W. inter-
nispinosum Zones.

The genus Corongoceras is represented in Cerro
Lotena by its type species ©. lotenoense. This genus
is widely distributed in the Andean Tithonian. Apart
from the type species referred to by Srarn (1925,
p- 144) from Corongo, Perü, 5 further species are
known in South America, as follows: C. mendozanum
(BEHR.), C. alternans (GERTH), C. duraznense KrAnNTZ,
C. submendozanum Krantz and C. rigali Leanza.
In Cuba C. filicostatum ImLay (1942) and in Mexico
C. mendozanum and C. cordobai VERMA & WESTER-
MANN (1973) have been recorded. Elsewhere in the
world the genus is known from Madagascar (CoL-
LIGNon, 1960), Algeria (Roman, 1936), Nepal
(HELMSTEADT, 1969) and Spain (OLorız, 1978). The
species from Cerro Lotena occurs in the beds of the
W. internispinosum Zone. Field observations indicate
that it is not common in the overlying C. alternans
Zone of the Upper Tithonian (cf. A. F. Leanza, 1945).

No true Boreal elements have been recorded in the
fauna from Cerro Lotena. It should also be remarked
that no representatives of the genera Lytoceras or
Phylloceras have been found. This feature, con-
sidering the paleogeographical and paleoenvironment-
al conditions under which the Vaca Muerta Formation
was deposited, favours the suggestion of SpatH (1932,
p. 151, 152) that these were pelagic organisms which
were not adapted to living in shallow epicontinental
seas.

Preservationoftheammonite
fauna

The degree of preservation of the fossils depends
upon their stratigraphic position. In the lower part of
the Vaca Muerta Formation (V. mendozanus and
P. zitteli Zones), most of the specimens have been
affected by diagenetic compaction and usually one
side is better preserved than the other. All the fossils
are calcified, with calcite crystals commonly present in
the camerae. Oysters are attached to some specimens,
particularly to the umbilicus and appear to be true

epizoans. Specimens are generally dark grey in colour

and the suture line can be observed in most cases.

In the upper part of the Vaca Muerta Formation
(A. proximus and W. internispinosum Zones) the am-
monites shells are commonly occuring as recrystallized
to white yellowish-white, granular, calcium carbona-
te. Both the fossils and the matrix consists of the same
material, and the test of the shell is usually preserved.
The suture lines are not preserved in any specimens,
a fact which creates a serious problem in the determi-
nation of taxonomic position.

V. TAXONOMIC REVISION

The classification used here at the generic level is in
accordance with the Treatise of Invertebrate Paleon-
tology (ArkELL et al., 1957). Parastreblites DonzE &
Enay (1961) is regarded as a genus and not a subgenus
of Taramelliceras as originally described. In Table I

the suggested taxonomic changes are summarized.
The reasons for these changes are given in the discus-
sions of the respective genera and species in the syste-
matic descriptions.

TABLE I

Revision of Ammonite Species

Previous classification

Pseudolissoceras zitteli (BURCK.) ARNOULD-SAGET, 1951,
p- 9, Pl. I, figs. 12a-c, 13a-c, 14, 16a-c

Oppelia nimbata STEUER (non a 1897, p. 74, a
VII, figs. 16, 17.
Pseudinvoluticeras decipiens Sa 1925, p- 1247 =
$. payeri Douv. (non a 1910, p. 18, 3 III, Dass
3a-b e

N Ttenbensi en, 1931, p. 423, a
48, figs. 322, 323

Virgatosphinctes erinoides ans (non Buncx) 1954,
p- 109, pl. 15, fig. 1 ER
Virgatosphinctes windhauseni WERER 1931,
pl. 48, figs. 324, 325

P- 425,

Holcodiscus wilfridi Douv., 1910, p. 12, pl. II, fig. 6

Perisphinctes aff. transitorins BuRcK. (non OpreL), 1903,
p- 40, pl. V, figs. 4-9 ee ARE ee:
Aulacosphinctes cf. A. transitorins WEAVER (non .
1931, p. 415, pl. 45, fig. 306

Perisphinctes contiguns BurcK. (non Caruno) 1903,
p- 38, pl. IV, figs. 7-10

Perisphinctes choicensis Burck., 1903, p. 50, nl v1, "fin
10-12, pl. VIII, fig. 6

Virgatosphinctes cf. raja INDANS re Unric), 1954,
p. 110, pl. 14, figs. 1-3

Perisphinctes erinoides Burck. 1903, p. :
Perisphinctes aff. erinus Burck. (non men 1900a,
p- 42, pl. XXV, fig. 1

Aulacosphinctes windhauseni WEAvER; 1931, p. 412, al
44, fig. 300 SER

Oppelia (Neochetoceras) waageni KranTz (non ZITTEL),
p. 434 IR IA VRDE VERESAET VERRSFE
Oppelia (Neoochetoceras) waageni WEAVER (non Zi
TEL), 1931, p. 399

New classification

? Pseudolissoceras psendooolithicum (HAuPrT)

Glochiceras steueri n. sp.

Psendinvoluticeras douvillei SpatH
Pseudinvoluticeras douvillei SpaTH
Pseudinvoluticeras douvillei SPATH
Pseudinvoluticeras windhauseni (WEAYv.)
n. comb.

Pseudinvoluticeras (?) wilfridi (Douv.)
Virgatosphinctes evolutus n. sp.
Virgatosphinctes evolutus n. sp.

Virgatosphinctes evolutus n. sp.

Choicensisphinctes choicensis (BURCK.)
gen. nov.

Choicensisphinctes choicensis (BURCK.)
Choicensisphinctes erinoides (BuRcK.) n. comb.

Choicensisphinctes erinoides (Burck.)

Subdichotomoceras windhauseni (WEAVv.)
n. comb.

? Parastreblites comahuensis n. sp.

VMESMMONITTE ZONESAND’GORRELATIONS

The ammonite fauna of the Vaca Muerta Formation
can be grouped into 4 associations which basically cor-
respond to ammonite zones previously established for
the Andean Tithonian by other authors (BURCKHARDT,
1900a, 1900b, 1903; WEAVvER, 1931; A. F. LEANZA,
1945, 1947; GROEBER, 1946; GROEBER et al., 1952;
StiranTicıc, 1969; H. Leanza, 1973; H. LEANzA &
C. Huco, 1977). These are the V. mendozanus
Zone, the P. zitteli Zone, the A. proximus Zone and
the W. internispinosum Zone. The first zone is located
in the uppermost Lower Tithonian while the remain-
ing three constitute the Middle Tithonian. Upper
Tithonian sediments are present in the overlying
Picun Leufiü Formation, but their coastal facies
prevented the establishment of an ammonite fauna.
In Cerro Lotena, only Substeneroceras has been
recorded from this formation (H. LEanza, 1973).

Data from this and previous studies indicate that
the V. mendozanus Zone is not a completely satisfac-
tory one. This is because this species is present only in
very small numbers within the Neuqu&n and Mendoza
basin, and, moreover, its systematic position is still
rather uncertain. Progress has been made, however,
in the W. internispinosum Zone, where genera which
previously were unknown or poorly documented have
now been identified and described. In Table II, cor-
relations between Cerro Lotena (Neuquen) and
Sierra Azul (Mendoza) are given.

The Virgatosphinctes mendozanus!) Zone

This zone was originally established by BuRCKHARDT
(1900a, p. 82; 1903, p. 106) as those sediments con-
taining numerous Virgatosphinctinae in the basal por-
tion of the Vaca Muerta Formation, at the beginning
of the Tithonian transgression in the Neuquen and

1) The history of this species begins with BURCKHARDT
(1900a, p. 41, pl. 25, figs. 6-8), who figured some specimens
from Portezuelo Montaües as Perisphinctes aff. lothari
CHOFFAT. Three years later, the same author referred to
the same specimens as Virgatites scythicus VISCHNIAKOFF
(BURCKHARDT, 1903, p. 45, pl. VII, figs. 1-8) a determination
which in this case was supported by Pavrow. This latter
classification was questioned by Douvırz£ (1910, p. 7) who,
when establishing Virgatites andesensis Douvirı£ on the
basis of material from Neuqu£n, included Virgatites scythi-
cus BURCK. (non VISCHNIAKOFF) in this species. BURCK-
HARDT himself (1911a, foot note; 1911b, p. 772) partly
accepted the opinion of Douvirı£ in the sense that the spe-
cimens from Portezuelo Montanes did not correspond to
the cited Russian species, but also stated that his Virgatites
scythicus could be included in the synonymic list of V. an-
desensis DouvıLı£. Consequently, BurckHArpr (1911a,
p. 482, foot note) proposed a new name for the specimens of
Paso Mantanes — Virgatites mendozanus — retaining the

Mendoza basin. The type locality is situated in the
region between Cajön del Burro and the Choica River
valley at the beginning of the Rio Grande, Mendoza
province, Argentina. This zone, which is characteriz-
ed by a notable uniformity throughout the basin, con-
sists of bituminous black shales with common, variably
sized calcareous nodules and concretions, which usual-
ly contain Virgatosphinctinae.

On the basis of studies of several sections of the
Vaca Muerta Formation in the Neuquen and Men-
doza basin, Leanza & Huco (1977, p. 250) suggested
that the V. mendozanus Zone could be revised. This
zone, which occurs at the base of the Tithonian trans-
gressive sequence across hundreds of kilometers, fre-
quently lacks V. mendozanus itself. In its place,
Choicensisphinctes choicensis is often present. This
species has been recorded in the sections of Cerro
Lotena, Picun Leufü, Mallin de los Caballos, Mallın
Quemado, Cajön de Almaza, Bardas Blancas and
Arroyo Cieneguitas. V. mendozanus was found only
in the Puerta Curaco section. It is worth noting that
although WEAvER (1931) stated that specimens of
V. mendozanus, particularly in central and southern
Neuquen, constituted up to 75 %/o of this assemblage,
he neither illustrated nor described this species. Ne-
vertheless, on the basis of priority, together with the
fact that Ch. choicensis is an endemic form, the present
author favours retention of the original name, though
noting the rarity of the species and its somewhat un-
certain systematic position.

In Cerro Lotena, the V. mendozanus Zone is 25 m
thick and contains the following ammonites: Pseudin-
voluticeras douvillei SpatH, P. windhauseni (WEav.)
n. comb., P. (?) wilfridi (Douv.), Virgatosphinctes
andesensis (Douv.), V. mexicanus (Burck.), V. dense-
plicatus rotundus SpaTH, V. evolutus n. sp., V. burck-
hardti (Douv.) Choicensisphinctes choicensis (BURCK.),

name V. andesensis only for the specimens figured by Dov-
vıLLE in 1910. A few years later, STEIGER (1914, p. 502)
included BURCKHARDT’s species in the genus Perisphinctes.
SpatH (1927-33, p. 527) also commented on this problem,
and included the mendozanus species of BURCKHARDT in the
genus Dorsoplanites. However, five years later, after stu-
dying it in more detail he stated that the similarity with
Dorsoplanites is “probably entirely superficial” (Sratn,
1936, p. 72) and “could equally well be included in Virga-
tosphinctes” (SPATH, op. cit., p. 29). Recently, R. Enay
(1964, p. 365) included the same species in Subplanites.
However, the identification of BURCKHARDT’s species as
belonging to the genus Virgatosphinctes, as made by WEA-
vER (1931) SpatH (1936), Inpans (1954) and many others,
has gained more widespread popularity. Considering the
shortage of material which could throw light on the taxo-
nomic filiation of this enigmatic species, the present author
prefers to place it in Virgatosphinctes retaining in this way
the more widely known name.

TABLE II

Ammonite Zones in Cerro Lotena and Sierra Azul

Cerro Lotena Sierra Azul
(Neuquen) (Mendoza)

O. curacoensis
N. wichmanni
S. damesi

Ammonites Zones

ZzpenZoZer><

A.noduliferum

ZeuubsuRumu

Ss. koeneni

C. alternans

W. internispinosum

Au. proximus

P. zitteli

V. mendozanus

Abbreviations: © = Olcostephanus, N = Neocomites, S = Spiticeras, A = Argentiniceras, Ss = Substeueroceras, C =
Corongoceras, W = Windhauseniceras, Au = Aulacosphinctes, P = Pseudolissoceras, V = Virgatosphinctes, L = Lower,
M = Middle, U = Upper.

Ch. choicensis sutilis n. ssp. and Ch. erinoides (Burck.).
V. mendozanus is absent.

On the basis of the studies of BURCKHARDT (1900a,
1900b, 1903), Haupr (1907), Krantz (1926, 1928),
WEAVER (1931) and Inpans (1954) this zone is placed
in the Lower Tithonian. This assignment is confirmed
in the case of Cerro Lotena by the presence of the
genus Pseudinvoluticeras, common in sediments of
Lower Tithonian age in Somaliland (SparH, 1925),
Madagascar (CorLıicnon, 1960) and Mexico (VERMA &
WESTERMANN, 1973). Zeıss (1968) has correlated this
zone with the uppermost Lower Tithonian Parapalla-
siceras palatinum Zone of the Franconia region.

The Pseudolissoceras zitteli Zone

This zone, which overlies the V. mendozanus Zone
in the region situated between Cajön del Burro and
the Choica River valley, was proposed by BURCKHARDT
(1900a, p. 83; 1903, p. 107). It has a wide distribu-
tion throughout the whole Neuqu&n and Mendoza
basın (cf. LEanza & Huco, 1977). In Cerro Lotena,
the P. zitteli Zone is 26 m thick and contains numerous
variably sized specimens of P. zitteli, in association
with limited numbers of P. psendooolithicum (Haupr),
Glochiceras steueri n. sp., Hildoglochiceras wiedmanni
n. sp. and Parastreblites comahuensis n. sp. Also
present are abundant Laevaptychus (cf. CLoss, 1961a,
b) and vertebrate bones and fish scales (see WınDHAU-
sENn, 1914).

In the chapters dealing with faunal analysis and
systematics descriptions, data are given on the distri-
bution of the genus Psendolissoceras and its species.
On the basis of the studies by Haurr (1907), KRANTZ
(1926, 1928), WEAVvER (1931), H. GERTH (1935),
GROEBER (1946), GROEBER et al. (1952), STIPANICIC
(1969), H. Leanza (1973), and Leanza & Huco
(1977), the age of the P. zitteli Zone can be taken as
the lowermost Middle Tithonian, although the pre-
sence of the new haploceratids cescribed in this report
suggests a slightly older age. Considering the upper-
most Lower Tithonian age of the underlying ammoni-
te zone, the P. zitteli Zone is placed in the lowermost
Middle Tithonian. The same age for the genus Pseu-
dolissoceras had been suggested by BArTHEL (1962) and
Zeıss (1968). The record of P. zitteli by ARNOULD-
SacET (1951, 1951a) in the Upper Tithonian of Tuni-
sia does not seem to be concordant with its known
stratigraphic distribution. If the bipartite division of
the Tithonian stage is used, the P. zitteli Zone would
fall into the Lower Tithonian (cf. R. Enar, 1964,
1972, 1973; J. WIEDMANN, 1968; VERMA & WESTER-
MANN, 1973).

The Aulacosphinctes proximus Zone

This zone is equivalent to the Aulacosphinctes co-
lubrinoides Zone proposed by BURCKHARDT (1900a,
p. 84; 1903, p. 108), and overlies the ?. zitteli Zone.
Following the works from GROEBER (1946) and

GROEBER et al. (1952), the A. colubrinoides Zone was
renamed as the A. proximus Zone, a name which was
later accepted by Sriranıcıc (1969), H. LEAnzA (1973)
and LEanza & Huco (1977). This is the most poorly
defined zone in the Andean Tithonian because,
excluding Subdichotomoceras, Aspidoceras and Pseud-
himalayites it contains no other ammonite genera.
Moreover, many species of Aulacosphinctes range
throughout almost the whole Tithonian Stage. How-
ever, the vertical extent of the A. proximus Zone can
be defined if it is considered as the interval that has as
its base the last representatives of P. zitteli, and as its
top the first occurrence of the species W. internispino-
sum. So defined, this zone at Cerro Lotena is 21 m
thick, and in addition to numerous specimens of
A. proximus, contains Subdichotomoceras sp. juv.
indet, Laevaptychus crassissimus (HAurT), Aspidoceras
andinum (STEUER), A. neuquensis (WEAv.), and Pseud-
bimalayites steinmanni (STEUER).

The A. proximus Zone has also been identified in
the Chilean part of the Andean geosyncline (CoRVALÄN
& Perez, 1958; CorvaLAn, 1959). As it occurs
between the ?. zitteli and W. internispinosum Zones,
its age accordingly falls into the middle part of the
Middle Tithonian.

The Windhauseniceras internispinosum Zone

This zone was originally proposed by WEAVER
(1931, p. 46), who placed it in the Upper Tithonian
Later, A. F. Leanza (1945, table hors de
text) placed this zone in the lowermost Upper Titho-
nian, noting that only Wichmanniceras mirum occur-
red in association with the index species. ARKELL
(1956, p. 582), who considered this zone uncorrela-
table with those of the European Upper Tithonian,
placed it in the Middle Tithonian.

Though W. internispinosum is an entirely endemic
form, it is very abundant at Cerro Lotena in the
upper part of the Vaca Muerta Formation. In this
zone, ammonites have been found which were pre-
viously unknown or poorly documented in the Andean
domain, but which now allow its age to be more pre-
cisely determined. The zone is 38 m thick and con-
tains the following ammonites: Windhauseniceras
internispinosum (Krantz), Hemispiticeras aff. H.
steinmani (STEUER), Pachysphinctes americanensis n.
sp., Corongoceras lotenoense SpaTH, Subdichotomoce-
ras windhauseni (WEAv.), S. araucanense n. sp., Aula-
cosphinctoides aft. A. hundesianus (UHLiıc), A. sp.
indet., Parapallasiceras afl. P. psendocolubrinoides
OrLorız, P. aff. recticosta OLorız, P. sp. indet. and
Aspidoceras enomphalum STEUER.

Assemblages containing Subdichotomoceras, Pachy-
sphinctes, Aulacosphinctoides and Aspidoceras have
been reported from the Middle Katrol beds of Cutch,
which Arkeıı (1956, p. 388) refers to the Middle Kim-
meridgian with interrogant. In the Tendaguru Group

sensu lato.

of east Africa, Subdichotomoceras and Pachysphinctes
have also been found together, and were referred by
ArKELL (1956, p. 335) to the uppermost Kimmeridgian.
Considering the equivalence of the Middle and Upper
Kimmeridgian to the Lower and Middle Tithonian,
and taking into account the stratigraphic position of
the W. internispinosum Zone, it is accordingly placed
more properly in the Middle Tithonian than in the
Upper Tithonian. Moreover, the genus Parapallasi-
ceras, which is also present in Cerro Lotena, apparent-
ly never crosses into levels younger than the Middle
Tithonian (cf. Zeıss, 1968). Although the genus Co-
rongoceras is common in the Andean Upper Tithonian
(cf. A. F. Leanza, 1945), C. lotenoense SPATH appears
to occur in the Neuquen basin at somewhat lower
levels (cf. H. LEanza, 1973, p. 116; 1975, p. 583). On
the basis of these reasons, the W. internispinosum
Zone is placed in the uppermost Middle Tithonian,
and is probably equivalent to the Burckhardticeras
Zone in the Betic ranges of southern Spain (cf. OLorız,
1978).

The Upper Tithonian of the Andean domain there-
fore is entirely represented by the Corongoceras alter-
nans and Substeueroceras koeneni Zones. The first
zone, proposed by A. F. LEAnzA (1945), appears inme-
diately above the W. internispinosum Zone and pro-
bably is equivalent to the Berriasella delphinensis
Zone of southeast France, and to the lower part of the
“Virgatosphinctes” transitorius Zone of the Alpine
region (cf. Enay, 1964). The Substeueroceras koeneni
Zone is equivalent to the Berriasella chaperi Zone of
southeast France and to the upper part of the „Virga-
tosphinctes“ transitorius Zone of the Alpine region.
Therefore, the C. alternans and $. koeneni Zones can
easily be correlated with the European Ardescian.

As noted above, the Upper Tithonian is represented
at Cerro Lotena in the overlying Picün Leufü For-
mation. However, this formation lacks the ammoni-
tes so common in more pelagic facies, such as in the
Sierra Azul in the southern part of Mendoza. In
Table III the ammonite zonation of the Andean Ti-
thonian is given.

TABLE III
Ammonite Zonation of the Andean Tithonian

Ammonite Zones Fossils

SUBSTEUEROCERAS
KOENENI

Aulacosphinctes azulensis LEANZA, A. mangaensis (STEUER), Pectinati-
tes (?) striolatus (STEUER), Berriasella fraudans inflata Leanza, B. inae-

quicostata GERTH, Parodontoceras calistoides (BEHR.), Aspidoceras
longaevum LEANzA, Substeneroceras exstans Leanza, Blanfordiceras
vetustum (STEUER), Himalayites andinus H. LEANZA, Spiticeras acutum

CORONGOCERAS
ALTERNANS

Micrancanthoceras tapiai Leanza, M. lamberti Leanza, B. pastorei
LEANZA, B. australis LEANzA, B. krantzi LEanza, B. bardensis KRANTZ,

B. (?) delhaesi LEanza.

WINDHAUSENICERAS
INTERNISPINOSUM

Pachysphinctes americanensis H. Leanza, Hemispiticeras aff. A. stein-
manni (STEUER), Subdichotomoceras araucanense H. LEANZzA, S. wind-

hauseni (Weav.), Parapallasiceras aff. pseudocolubrinoides OLorız,
P. aff. P. recticosta OLorız, P. sp. indet., Aulacosphinctoides aff.
A. hundesianus (UnLic), Aspidoceras euomphalum STEUER, Corongo-
ceras lotenoense SPATH.

AULACOSPHINCTES
PROXIMUS

Subdichotomoceras sp. juv. indet. Pseudhimalayites steinmanni (STEU-
ER), Aspidoceras andınum STEUER, A. neuquensis WEav., Laevaptychus

crassissimus (HAUPT).

PSEUDOLISSOCERAS
ZITTELT

Pseudolissoceras pseudooolithicum (HaurT), Glochiceras steneri H. LE-
AnzA, Hildoglochiceras wiedmanni H. Leanza, Parastreblites coma-

huensis H. LEANZA.

VIRGATOSPHINCTES
MENDOZANUS

Pseudinvoluticeras douvillei Spatn, P. windhauseni (Weav.), P. (?)
wilfridi (Douv.), Choicensisphinctes choicensis (Burck.), Ch. choicen-

sis sutilis H. Leanza, Ch. erinoides (Burck.), Virgatosphinctes ande-
sensis (Douv.), V. mexicanus (Burck.), V. burckhardti (Douv.), V. den-
seplicatus rotundus SpatH, V. evolutus H. Leanza, Subplanites ma-
largüensis SPATH.

VILSMSEEMANTIC DESERIPFFRONS

Measurements and abbreviations

All measurements are in millimeters and include
the ornament. With rare exceptions they are taken on
the internal mold. "The abbreviations employed in the
systematic descriptions are as follows:

D = maximum diameter at a given growth stage

U = diameter of umbilicus measured at seam

H = height of the whorl measured in the plane of
coiling

W = maximum width of whorl at right angles to
the plane of coiling

In most cases, measurements are given only for the
figured and better preserved specimens.

The suture line abbreviations are the following:

E = external lobe
L = lateral lobe
U = umbilical lobe

Repositories

All specimens studied in this report are deposited at
the Geological Survey of Argentina (Servicio Geolö-
gico Nacional, Repüblica Argentina), with the excep-
tion of 3 specimens from the F. von Huene collection
at the University of Tübingen, Germany.

The following abbreviation are employed:
S.G.N. = Servicio Geolögico Nacional, Repüblica
Argentina.
G.P.1.T. = Institut und Museum für Geologie und
Paläontologie Tübingen, Germany.

Gypsum copies of the specimens figured in this

report are also deposited at the Tübingen Institute.

Order AMMONOIDEA Zırteı, 1884
Suborder AMMONITINA HyAarr, 1889
Superfamily HAPLOCERATACEAE Zıtteı, 1884
Family HAPLOCERATIDAE Zırtteı, 1884
Genus PSEUDOLISSOCERAS SpATH, 1925

Type species. — Neumayria zitteli Burck-
HARDT, 1903, p. 55, pl. 10, figs. 1,2. SD Roman, 1938,
p- 176.

In the genus Pseudolissoceras two groups with
distinctive characteristics can be clearly distin-
guished: the Pseudolissoceras zitteli group and the
Pseudolissoceras rasile group.

Both groups have in common a characteristic suture
line, with E and L wide but not deep; both the width
and depth of the E/U saddle equivalent to almost
half of the E/L saddle. The second lateral saddle
(E/U) is diagnostic and clearly differs from that of

the genus Haploceras ZiTTEL, 1870 (type species: Am-
monites elimatus OppzL, in ZITTEL, 1868, pl. 13, (figs.
1a—c, SD SpatH, 1923) which displays an E/U saddle
larger and higher than the E/L saddle (cf. ScHinDE-
WOLF, 1963, p. 379, text fig. 208).

The group of P. zitteli (BURCKHARDT, 1903, p. 55,
pl. 10, figs. 1—8) is characterized by very involute
shells (U/D = 0.18 to 0.26), ornamentation with fine
falcoidal striae, whorl sections higher than wide, and
sharp umbilical borders. The following species have
been placed in this group: P. zitteli (Haurt, 1907,
pl. 7, figs. 3a, b; 4a, c), P. zitteli (Krantz, 1928, pl. 1,
fig. 6), P. zitteli (WEAVER, 1931, pl. 43, fig. 291), P. cf.
zitteli (Imray, 1942, pl. 4, figs. 1, 3, 4, 7, 8, 11, 12),
P. zitteli (Ororız, 1978, pl. 2, fig. 12, text fig. 43),
P. advena (Spath, 1950, pl. 6, figs. 9—10), P. concorsi
(Donze & Enar, 1961, pl. 1, fig. 1, text fig. 4), P. ba-
varıcum (BARTHEL, 1962, pl. 2, figs. 7—9) and P. zit-
teli (VERMA & WESTERMANN, 1973, pl. 26, figs. 3—5,
text figs. 12—13).

The group of P. rasile (Opreı, 1865, p. 549; in
ZırteL, 1870, p. 55, pl. 4, figs, 2, 3) is characterized by
more evolute whorls (U/D = 0.22 to 0.36), smooth
tests, somewhat inflated shells, whorl sections almost
as wide as high, and the absence of sharp umbilical
borders. This group differs from Haploceras only in
its suture line (cf. supra); the morphology of the shells
is almost identical. The following species have been
placed in this group: P. rasile inflatum (ZırteL, 1870,
pl. 4, figs. 2), P. rasile planiusculum (Zırteı, 1870,
pl. 4, figs. 3a—c) which was reported by BEHRENDSEN
(1892, p. 388) from Rodeo Viejo and Malargüe (Men-
doza, Argentina), P. planiusculum (ZırreL) (Avram,
1976, pl. 7, figs. 5a, b; pl. 8, figs. 2a, b, text fig.
10a—c), P. subrasile (BURCKHARDT, 1906, pl. 34, figs.
8—11) and P. pseudooolithicum (Haupt, 1907, pl. 8,
figs. 2a—c). It is possible that ?. zitteli of ARNOULD-
SAGET (1951, pl. 1, figs. 12—14, 16) also belongs to this
group (see BARTHEL, 1962, p. 14).

In the Cerro Lotena section, 55 specimens attributed
to ?. zitteli have been found; only 3 specimens have
been identified as P. psendooolithicum.

Pseudolissoceras zitteli (BURCKHARDT, 1903)
Pl. 1, Figs. 1a—b, 2a—b, Text-Figs. 2a and 3.

1903 Neumayria Zitteli BURCKHARDT, p. 55, pl. 10, figs.
1-8.

1907 Neumayria Zitteli BURCKHARDT — HaupT, p. 200,
pl. 7, figs. 3a-b, 4a-c.

1925 Pseudolissoceras zitteli (BURCKHARDT) — SPATH, p
113 (Gen. nov.).

1926 Haploceras (Pseudolissoceras) Zitteli (BURCKHARDT)
— KRANTZ, p. 436, pl. 17, figs. 4,5.

Figure 2: Whorl sections of Haploceratidae and Oppeliidae.
a: Pseudolissoceras zitteli, S.G.N. 8887/1; b: P. pseudoooli-
thicum, S.G.N. 7327/1; c: Hildoglochiceras wiedmanni
n. sp., G.P.I.T. 1545/1 (Holotype); d: Glochiceras steneri
n. sp., S.G.N. 7333/5 (Paratype); e: Parastreblites coma-
huensis n. sp., S.G.N. 7326. (Holotype). Natural size.

1928 Haploceras (Pseudolissoceras) Zitteli (BURCKHARDT)
— KRrANTZ, p. 18, pl. 1, fig. 6.

1931 Psendolissoceras zitteli (BURCKHARDT) — WEAVER,
p. 401, pl. 43, fig. 291.

1938 Haploceras (Psendolissoceras) Zitteli (BURCKHARDT)
— Roman, p. 176, pl. 16, fig. 170 (Reproduction of
BURCKHARDT’s original: pl. 10, figs. 1, 2; 1903).

1942 Pseudolissoceras cf. P. zitteli (BURCKHARDT) — IMLAY,
p. 1443, pl. 4, figs. 1,3, 4,7, 8, 11, 12.

1950 Pseudolissoceras zitteli (BURCKHARDT) — SPATH, p.
101, pl. 6, figs. Sa-c.

1973 Pseudolissoceras zitteli (BURCKHARDT) — VERMA &
WESTERMANN, p. 168, pl. 26, figs. 3-5, text figs. 12-13.

1978 Pseudolissoceras zitteli (BURCKHARDT) — OLORIZ,

p- 34, pl. 2, fig. 12, text fig. 43.

Figure 3:

Material. — 55 specimens, mostly well pre-
served. S.G.N. 7325/1—2; S. G. N. 7331/1—4, 6;
S.G.N. 7333/1—4; S.G.N. 7334/1—4; S.G.N. 8887/
1—2; S.G.N. 8897/1; S.G.N. 8920/1—4; S.G.N.
8938/1—3; S.G.N. 8925/1—21; S.G.N. 8926/1—9.
The specimens illustrated in plate 1, figs. Ja—b and
2a—b, correspond respectively to numbers S.G.N.
7325/1 and S.G.N. 7333/1.

Description. — The largest specimen has a
diameter of 124 mm (S.G.N. 7334/1) and the smallest
a diameter of only 12.8 mm (S. G. N. 1925/14). The
diameters of the remaining samples transitionally
cover the range between these extremes. The shell is
involute. On the average, the umbilicus of the smaller
specimens occupies 18 °/o of the shell diameter, and up
to 26/0 in the larger specimens. The most extreme
ratios were measured in specimens S.G.N. 7333/1
(U/D = 0.13) and S.G.N. 7334/1 (U/D = 0.27).
This latter ratio belongs to the specimen of maximum
size (diameter = 124 mm). These data clearly show
the tendency for the shell to become more evolute
with age.

Whorl sections are higher than wide (text-fig. 2a).
Umbilical borders become sharper with increase in
shell size: smaller specimens show rounded umbilical
borders, while larger ones exhibit an umbilical slope
which is strongly inclined and sometimes almost verti-
cal. The flanks are gently convex and the periphery
sligthly rounded. In some specimens whose tests have
been preserved it is possible to observe very fine
somewhat falcoidal striae.

The suture line (text-fig. 3) coincides exactly with
that originally described by BurckHARrDT (1903, p. 55).
The E/L saddle is wide and is divided by an accessory
lobe in two asymmetrical parts. The L lobe is very
shallow and somewhat less wide than E/L. The E/U
saddle has a width almost equivalent to half the E/L
saddle, and also is divided by a small lobe into two
asymmetrical parts. There are also two U lobes (U,
and U,) which are not very elaborate.

0, U

Suture line of Pseudolissoceras zitteli (Burck.), S.G.N. 7325/1. X3.

Measurements (better-preserved specimens only)

Specimen n° D UUD H WW HXW
S:G.NS 27325117 2947 2257 026° 407 267 1.53
S.G.N. 7325/2 51 12° 023 23 14 1.64
S.G.N. 7331.18 117229750247 427277155
S!GIN 2 7331/25021695.11277205172 337 219771.73
S.G.N. 7331/3 46 8,0177 247127 72.00
SIG.N. 7331/47 8171777020737 2271754
SGN 7331/60 14 3020.21 7 51.40
S.G.N. 7333/1 51 7.0.1352 237 2157717836
S.G.N. 7333/2 41 9730217 2227127511833
SIGINS , 7333/3532 3792571971277 71558
SIGIN. 7333/42238 7197 0.267 207 1271.66
SGINZ. 7785411021247 7347 .027 517357 145
S.G.N. 7334/2 53 952.916 2972157 31.93
SIG.Nz 7334/35839 107.01727°297 7147 72.07.
S!G.N. 8920/17 53710779187 297167 1.81
S.G.N. 8920/2 44 72:0,150. 02371371576
S.G.N. 8920/74 45 10 022 21 15 1.40
SIG.N. 8887/97 237 0.23 42 25, 71.68
S.G.N. 8897/3 33 7020,21 218712721550
S.G.N. 8926/1 43 IE PIE ZT 173
S.G.N. 8926/2 37 877.021 18712777559
S.G.N. 8926/3° 31 722, 02271772117 215%
S.G.N. 8926/4 31 6720.19 5172 1970
S:G.N. '8926/5 25 57 70.207°7147 107 1:49
S.G.N. 8926/6 28 ol ze ee
S.G.N. 8926/77 23 472047713 9 1.44
S.G.N. 8926/8 21 3.5,.0516=.10157.521.53
S.G.N. 8926/99 17 4 0.23 7 5.9. 1.27
S:GE N 8925120 37 7,9182. 02072127771'66
S.G.N. 8925/3 34 70.0200 18-1977 1780
S:G.N. 8925/47726 6 70.237 13 91.44
S:G.N. 8925/57 23 550.230 12 972133
SIGIN? 7 8925/6 19 40.2101 7.5 1.46
S.G.N. 8925/77 18 3:5.0.197°°109 7142.
S:G.N„ 8925/18 175370417 19 6.5, 1453
S.G.N. 38925/9 16 470:25 8 5.5 1.45
S.G.N. 8925/10 17.5 3.5 0.20 8 5.5 1.45
S:G.N. 8925/4117 15:5. 37 0.19 8 5721.60
S.G.N. 8925/12 15 3 0.20 9 6 1.50
S.G.N. 8925/13 17 3.1 0.18 8 5 1.60
S.G.N. 8925/14 12.8 2.5 0.19 7 4.8 1.45

Remarks. — The described specimens can be

readily placed in the genus Psendolissoceras SPATH
(1925, p. 113); specifically they correspond to P. zitte-
li (BuURCKHARDT, 1903). The specimens illustrated by
Haurr (1907), Krantz (1926, 1928) and WEAVER
(1931) were also found in Cerro Lotena. Some
authors have suggested that this species displays sexual
dimorphism (cf. VERMA & WESTERMANN, 1973, p. 145),
but the present study reveals that most of the smaller
specimens (up to 23 mm diameter) belong to immature
specimens which could have attained a greater size.

No specimens have been found with the whorl sec-

tion as figured by Haurr (1907, pl. 7, fig. 4b). It is
possible that this whorl section is from an unusually
crushed specimen and does not constitute a variety of
P. zitteli, as was suggested by BARTHEL (1962, p. 13,
15). It does, however, resemble the whorl section of
P. concorsi DonzE & Enay (1961, p. 46).

The inclusion of “Neumayria” subrasilis BuRcK-
HARDT (1906, p. 127, pl. 34, figs. 8—11) in the synony-
mic list of P. zitteli by VERMA & WESTERMANN (1973,
p. 168) appears to be inadequate because the umbili-
cus occupies 36 %/o of the diameter of the shell (U/D
= 0.36) and the whorls are only slightly higher than
wide (H/W = 1.14). These features suggest that
BURCKHARDT’s species is related to the P. rasile group
(cf. supra). The cited ratios are much more anomalous
for the P. zitteli group because “N.” subrasilis has
only an 18 mm diameter; for this size, the average
U/D ratio of the ?. zitteli group does not exceed
26 ®/o of the shell diameter.

Occurrence. — P. zitteli occurs in beds 3, 4, 5
and 6 of the Cerro Lotena section, in association with
P. psenudooolithicum, Glochiceras steueri n. sp., Para-
streblites comahuensis n. sp. and Hildoglochiceras
wiedmanni n. sp. The first specimens of P. zitteli
occur 25 m above the basal conglomerate of the Vaca
Muerta Formation.

Age. — Lowermost Middle Tithonian. P. zitteli
Zone.

Pseudolissoceras psendooolithicum (HauPpT, 1907)
Pl. 1, Figs. 5a—b; Text-Figs. 2b and 4.

1903 Neumayria psendooolithica HaurT, p. 200, pl. 8,
figs. 2a-c.

1926 Psendolissoceras pseudooolithicum (Haurt) —
KRANTZ, p. 435 (n. comb.)
1931 Psendolissoceras psendoolithica (Haupt) —

WEAVER, p. 400.
? 1951 Pseudolissoceras zitteli (BuRck.) — ARNOULD-SA-
GET, p. 9, pl. 1, figs. 12a-c, 13a-c, 14 and 16a-c.

Material. — Three well-preserved specimens.
S.G.N. 7328/1 (Figured in Pl. 1, Figs. 5a—b); S.G.N.
7328/2 and S.G.N. 7331/5.

Description. — Small shell, moderately
evolute, with suboval whorl section, only very slightly
higher than wide (text-fig. 2b). U/D = 0.26 to 0.27.
The umbilical slope is strongly inclined but passes
transitionally into the flanks forming an rounded
umbilical border. In contrast to ?. zitteli an umbilical
edge never exists. The flanks are clearly convex and
the periphery is rounded. The suture line (text-fig. 4)
strongly resembles that of P. zitteli, and is character-
ized by a wide E/L saddle divided by a small acces-
sory lobe in two asymmetrical parts. The L lobe is
wide and shallow and the E/U saddle has a width
equivalent to half of E/L. The U lobes are very
simple and not oblique.

DR ET E
N

Figure 4: Suture line of Pseudolissoceras pseudooolithicum
(Haupr), S.G.N. 7328/2. X 6.

Measurements —

Specimen n° D U’ U/D’ "EI "WI EUN
S:G.N. 7328/41 38 105.0.26: 1118.5.116° 1.15
S:G.N.. 7328/2 22 6,7.:0.270 2127 71172 1:09
SG.N. 7331/57 21 5.540.26- ° 11271027.10

Remarks. — The described specimens closely

resemble ?. pseudooolithicum (HaurT, 1907, p. 200,
pl. 8, figs. 2a—c) which, as previously mentioned, is
included in the ?. rasile group. The shell morphology
of P. pseudooolithicum strongly resembles that of
Haploceras elimatum (Opreı, 1865, ZırreL, 1870),
which is the type species of Haploceras by the sub-
sequent designation of SparH (1923); however, it dif-
fers in having a suture line with a E/U saddle as wide
as the E/L saddle and also clearly more elevated.
By contrast, HaupT’s species displays a smaller and
more depressed E/U, similar to that of P. zitteli. For
this reason the present author retains HaupT’s spe-
cies in the genus Pseudolissoceras. Acquisition of
better material may, however, eventually allow
establishment of a new genus.

It is very probable that “P. zitteli” of ArnouLD-
SAGET (1951, p. 9, pl. 1, figs. 12a—c, 13a—c, 14 and
16a—c) from Tunisia, on the basis of whorl shape,
dimensions and suture, could also belong to the species
here described.

It is worth remarking that Haurr (1907, p. 200)
gives an umbilicus diameter of 13.5 mm for the spe-
cimen figured in pl. 8, fig. 2a. This specimen, as can
be seen, is only 8 mm in diameter, with the other di-
mensions as stated by Haupt. Consequently, the U/D
ratio for this specimen is 0.25 and not 0.43, which
agrees very well with the described material.

Occurence. — Bed 6 of the Cerro Lotena sec-
tion, in association with ?. zitteli.

Age. — Lowermost Middle Tithonian. P. zitteli
Zone.

Genus GLOCHICERAS Hyarr, 1900

Type species. — Ammonites nimbatus OPPEL,
1863, p. 191, pl. 52, figs. 5a, b.

Glochiceras steneri n. sp.
Pl. 1, Figs. 3a—b, Text-Fig. 2d.

Holotype. — Oppelia nimbata STEUER (non
Opper), 1897, p. 74, pl. 7, fig. 17.
Paratypes. — Oppelia nimbata STEUER (non

Orper), 1897, p. 74, pl. 7, fig. 16 and specimen S.G.N.
7333/5, illustrated in Pl. 1, Figs. 3a—b of this paper.

Locus typicus. — Arroyo Cieneguitas, near
its Junction with the Salado river, southern Mendoza,
Argentina.

Stratum typicum. — Lower part of the
Vaca Muerta Formation, in the ?. zitteli Zone.

Derivatio nominis. — In honour of Doc-
tor Alfred STEUER, who described this species.

Diagnosis. — Small shell, involute and com-
pressed. Ornamentation characterized by fine striae
which form, in the internal part of the flanks, a lateral
linguiform band projecting towards the aperture.
This band is narrow and crenulate, and does not con-
stitute a true sulcus.

Material. — Only one specimen, complete, but
with aperture not preserved and umbilicus not very
clear. S.G.N.7333/5. The shell is somewhat crushed.

Description. — Small involute shell, with a
U/D ratio = 0.26. Whorl section somewhat subel-
liptical, higher than wide (text-fig. 2d). Umbilical
border gently rounded. Surface of the flanks slightly
convex. Periphery gently rounded. Ornamentation
characterized by fine striae which commence in the
umbilical slope and form a biconvex parabola over the
flanks. In the internal portion of the flanks, near the
umbilical border, the striae form a small and narrow
linguiform band, which is strongly directed towards
the aperture. Contiguous bundles of weak striae pro-
duce depressions, while bundles of strong striae form
elevated folds. Asa result, in the lateral linguiform
band, folds and depressions alternate throughout the
test. Neither the aperture nor the suture line could be
observed.

Measurements. — (inmm)
Specimen n?° D; UL EU/DZEHS EN GBEIUNG

S.G.N. 7333/5 23 6° 0.26 “lılT "50 72,22

Remarks. — Though the lappets of the speci-
men are not preserved, it is nevertheless possible, on
the basis of whorl shape and ornamentation, to include
it in the genus Glochiceras HyATT, 1900 (type species:

Ammonites nimbatus Opreı, 1863, p. 191, pl. 52,
figs. 5a, b). The genus Hildoglochiceras SparH, 1924
(type species: Hecticoceras latistrigatum UHuic, 1903,
p. 27, pl. 2, figs. 4a, c; pl. 3, fig. 5) is much more evolu-
te and exhibits a deep lateral groove and, as well,
subplanate flanks. “Paraglochiceras” CoLLicnon, 1960
(type species not designated) does not have a deep
lateral groove, but has a whorl shape more evolute
and inflated than the true Glochiceras.

Specifically, the specimen appears to be identical to
Oppelia nimbata STEUER (non Orrer) (1897, p. 74,
pl. 7, figs. 16 and 17) from Arroyo Cieneguitas, Men-
doza, Argentina. However, this species differs from
the genotype, G. nimbatum (OPPEL, op. cit.), as it shell
is much more compressed, and the strongly crenulate
lateral bands is in a position nearer to the umbilical
border. For these reasons, it is proposed to designate
the specimen as G. steneri n. sp., with Oppelia nimbata
STEUER, 1897, non OPPEL, 1863, as type species.

G. steneri n. sp. has closer affinities with the group
of G. fialar BuRCKHARDT (non OPprer) (1906, p. 77,
pl. 19, figs. 1—19; pl. 20, figs. 6, 12, 14, 15) from Ma-
zapil, Mexico, but differs from these forms in having a
more compressed and involute shell. The authentic
G. fialar (Oprer, 1863, p. 205, pl. 53, figs. 6a—c)
differs from G. steueri in being more evolute and in
displaying small crenulations around the periphery.
G. angustiumbilicatum Imzay (1939, p. 26, pl. 7, figs.
4—6), although bearing some similarities, clearly
differs in having a distinct umbilical border and a
strongly inclined umbilical slope. G. somalicum SpaTH
(1925, p. 114, pl. 16, fig. 7) is also more evolute and
has a distinct umbilical border and wider lateral band.
Finally, G. parabolistriatum Krantz (1926, p. 434,
pl. 15, figs. 3, 4) from Arroyo Loncoche, Mendoza,
Argentina, has a more inflated shell, with whorls
wider than high, and also a much wider lateral band.

Occurrence. — Lower part of the Vaca
Muerta Formation. Bed 3 of the Cerro Lotena sec-
tion, in association with ?. zitteli and H. wiedmanni.

Age. — Lowermost Middle Tithonian. P. zitteli
Zone.

Figure 5:

Genus HILDOGLOCHICERAS SpaTH, 1924

Type species. — Hecticoceras latistrigatum
Unuıc, 1903, p. 27, pl. 2, fig. 4a—e; pl. 3, fig. 5.

Hildoglochiceras wiedmanni n. sp.
Pl. 1, Figs. 44—b; Text-Figs. 2c and 5.

Holotype. — H. wiedmanni H. LEANZA n. sp.,
figured in Pl. 1, Figs. 4a—b. G.P.I.T. 1545/1.

Locus typicus. — Cerro Lotena, Neuquen
province, Argentina.

Stratum typicum. — Lower part of the

Vaca Muerta Formation.

Derivatio nominis. — In honour to the
outstanding ammonitologist, Prof. Dr. Jost WIED-
MANN, University of Tübingen, Germany.

Diagnosis. — Small shell, strongly evolute.
Whorl section somewhat compressed. Subplanate
flanks. Rounded umbilical border and convex peri-

phery. Ornamentation smooth, with the presence of
a lateral groove in the upper third of the flanks.
Somewhat below the groove there is a linguiform
parabola directed towards the aperture. Suture line
simple, with the E/L saddle very wide and the L lobe
narrow and deep.

Material. — One complete specimen, very well
preserved. Almost half of the last whorl belongs to
the body chamber. G.P.1.T. 1545/1.

Description. — Small evolute shell, with
umbilicus wide and shallow. U/D ratio = 0.40.
Whorl section somewhat compressed, subrectangular
in shape, with rounded borders (text-fig. 2c). Umbili-
cal slope gently inclined. Subplanate flanks and
rounded periphery. Ornamentation characterized by
a nitid and narrow groove in the upper third of the
flanks. In addition, very fine striae form a biconvex
parabola, producing in the middle part of the flank,
just below the groove, a linguiform process which pro-
jects towards the aperture.

The suture line (text.-fig. 5) is very simple, with the
E/L saddle very wide and the L lobe narrow and
deep; very poorly-developed accessory elements.

Suture line of Hildoglochiceras wiedmanni n. sp., G.P.1.T. 1545/1. X 6.

Measurements. —
Specimen n?° DEU UIDERET TE VIEL

GP] 81545/100222 9 0.40 9 671.5

Remarks. — The evolute shell with subplanate
flanks and the presence of the characteristic lateral
groove allow assignment of the specimen to the genus
Hildoglochiceras SpatH, 1924 (type species: Hectico-
ceras latistrigatum Umuic, 1903, p. 27, pl. 2, figs.
4a—e; pl. 3, fig. 5). Originally, the specimen was
catalogued in the collections of the University of Tü-
bingen as Haploceras n. sp. aff. tenuifalcatum, a spe-
cies described more than 100 years ago by NEUMAYR
(1873, p. 162, pl. 31, figs. ca—b) from the Aspidoce-
ras acanthicum Zone. However, this classification
does not appear to be correct as NEUMAYR’s species
does not have the lateral groove on the flanks.
Instead, the specimen is more similar to Haploceras
cf. tennuifalcatum Haurt (non NEuMmAYR) (1907,
p. 201) from Cerro Lotena, which bears lateral
grooves. Haupt compared his material with Ammo-
nites lingulatus QuEnstept (1858), which is actually
included in Glochiceras (cf. ZIEGLER, 1958). However,
the classification of this ammonite in either Glochice-
ras or Haploceras does not appear to be correct be-
cause the first genus has a completely smooth test,
without ornamentation, while the second one is always
much more involute. For these reasons, the specimen
is placed in Hildoglochiceras. Specifically, the closest
form is H. tennicostulatum CorLicnon (1960, pl. 145,
fig. 568, 569) from Madagascar, but this species is
more involute and shows some ribbing in the upper
part of the flanks. With respect to the other known
species of Hildoglochiceras, the differences are still
more obvious. For this reason, the specimen is con-
sidered as a new species named H. wiedmanni n. sp.

Occurence. — Lower part of the Vaca Muerta
Formation. Bed 3 of the Cerro Lotena section, in as-
sociation with ?. zitteli and G. steueri.

Age. — Lowermost Middle Tithonian. P. zitteli
Zone. y

U, =S U; (UF,

Figure 6:

Family OppELIIDAE BONARELLI, 1884
Subfamily TARAMELLICERATINAE SPATH, 1928
Genus PARASTREBLITES DONzE & EnaAY, 1961

Type species. — Oppelia tenuilobata (OrrEL)
var. circumnodosa FONTANNES, 1879, p. 23, pl. 3, fig. 6.

Parastreblites comahuensis n. sp.
Pl. 1, Figs. 6a—c; Text-Figs. 2e and 6

? 1926 Oppelia (Neochetoceras) Waageni ZiTTEL— KRANTZ,
p- 434.

? 1931 Oppelia (Neoochetoceras) waageni ZITTEL —
WEAVER, p. 399.
Holotype. — Parastreblitess comahuensis

H. LEANZA n. sp., figured in Pl. 1, Figs. 6a—c. S.G.N.
7326.

Locus typicus. — Southern slope of Cerro
Lotena, province of Neuqu£n, Argentina.
Stratum typicum. — Lower part of the

Vaca Muerta Formation. P. zitteli Zone.

Derivatio nominis. — From Comahue, an
araucan name for the region |ying between the Colo-
rado and Limay-Negro Rivers, and occupying the
province of Neuquen and part of the provinces of
La Pampa and Rio Negro.

Diagnosis. — Shell strongly involute, com-
pressed, with whorl section higher than wide. Umbi-
licus narrow and very deep. Venter rather acute but
rounded. Ornamentation characterized by fine striae
which describe a falcoidal trajectory over the flanks.
Suture line with L lobe narrow and much deeper than
the E lobe, and 3 accessory lobes (U,, U,and U, = S).

Material. — One specimen. S.G.N. 7326:
phragmocone very well preserved.

Description. — Because only one specimen
was found, little can be added to the diagnosis. The
most distinctive features are its suture line (text-
fig. 6), similar to that of the genus Parastreblites, and
its very narrow and deep umbilicus, which represents
only 11/0 of the shell diameter. "The umbilical slope
is vertical. The maximum width is in the upper part
of the internal third of the flanks (text-fig. 2e). The
periphery is narrowly rounded. The test is smooth
except for some weak striae which cross the flanks fal-

L E

Suture line of Parastreblites comahuensis n. sp., S.G.N. 7326/1. X2.

coidally. The suture line (text-fig. 6) shows an narrow
L lobe and 3 accessory lobes (U,, U,and U, = S).

Measurements. —
Specimen n° Du WwD HH WEHN

S.G.N. 7326 9010701177537 7287 21:89

Remarks. — The specimen resembles “Oppelia”
waageni ZırteL (1870, pl. 19, fig. 1) in its lack of
ornamentation and in its whorl section, which has a
rather narrowly rounded venter. In addition the
suture line of both displays three accessory elements.
However, the specimen from Cerro Lotena clearly
differs in having a deeper and narrower umbilicus.
The species waageni of ZırTeL was included by SPATH
(1925, p. 117, footnote) in the genus Neochetoceras
(type species: Ammonites steraspis OPrEL, 1863,
p- 251, pl. 69, figs. 1—9). This author implicitly con-
sidered Neochetoceras to include not only forms with
an acute venter, but also those with a rounded venter.
Later, Donze & Enax (1961, p. 52) transferred “Op-
pelia” waageni to Parastreblites, originally created by
this authors as a subgenus of Taramelliceras, con-
sidering Oppelia tennilobata (OPrEL) var. circumno-
dosa FonTAnnes (1879, p. 23, fig. 6) as type species.
DonzeE & Enary stated that its suture line was inter-
mediary between Taramelliceras (type species: Am-
monites trachynotus OpreL, 1863, pl. 56, fig. 4) and
Metahaploceras SpATH, 1925 (type species: Ammonites
lingulatus nudus QuENSTEDT, 1887, p. 852, pl. 92,
fig. 55) (cf. HoLper, 1955, p. 59).

Specifically, the specimen closely resembles P. waa-
geni (ZITTEL), and, to a lesser extent, P. similis (SPATH,
1925, p. 116, pl. 15, figs. 4a, b). However, the speci-
men clearly differs in its deeper and narrower umbili-
cus and in its almost smooth test. P. hölderi DonzE
& Enay (1961, p. 55, pl. 4, fig. 1, text-fig. 8) also
differs by having a somewhat more sculpturated test
with falcoidal ribbing. For these reasons, the speci-
men is proposed as the type of a new species named
P. comahuensis n. sp., its essential features being a shell
shape and suture line similar to those of Parastreblites,
and.a smooth test with deep and narrow umbilicus.

WEAVER (1931, p. 399) as well as Krantz (1926,
p. 434) have described but not figured some specimens
from Cerro Lotena referred to as Oppelia (Neocheto-
ceras) waageni. However, judging by their descrip-
tions, these forms probably belong to P. comahuensis
n. sp.

Occurence. — Lower part of the Vaca Muerta
Formation. Bed 5 of the Cerro Lotena section, in
association with ?. zitteli.

Age. — Lowermost Middle Tithonian. P. zitteli
Zone.

Superfamily PERISPHINCTACEAE STEINMANN,
1880
Family PERISPHINCTIDAE STEINMAnNN, 1890
Subfamily VIRGATOSPHINCTINAE SPATH, 1925
Genus PSEUDINVOLUTICERAS SpaATH, 1925

Type species. — Psendinvoluticeras somali-
cum SpATH, 1925, p. 141, pl. 15, figs. 7a—c, text-
fig. 10.

The genus Pseudinvoluticeras is characterized by an
involute shell, vertical umbilical slope and groups of
fine ribs which commence in periumbilical swellings
which with the age show a tendency to become smooth
and distant. The following originally described or
subsequently transferred species are known: P. soma-
licum SpatH (1925, p. 141, pl. 15, figs. 7a—c, text-
fig. 10), P. douvillei SpatH, 1925 (= Simbirskites bar-
botanus DouviLL£ non LAHusEn, 1910, p. 17, pl. 3,
figs. 4a, b), P. mozambicum Coıuicnon (1960, pl. 159,
fig. 631) and P. cf. P.mozambicum CoLLIGNON (VERMA
& WESTERMANN, 1973, p. 182, pl. 29, fig. 1).

The species found in Cerro Lotena, named P. wind-
hauseni (WEAVER) n. comb., can now be added to this
list.

“P. decipiens” SpatH (1925, p. 134; 1950, p. 115),
originally based on Simbirskites payeri DouviLL£
non TouLa (1910, p. 18, pl. 3, figs. 3a, b), is considered
for reasons given below as synonymous with P. dou-
villei SparHn. In the same species is also included
“Virgatosphinctes lotenoensis” WEAVER (1931, p. 423,
pl. 48, figs. 322, 323) and “Virgatosphinctes erinoi-
des” Inpans non BURCKHARDT (1954, p. 109, pl. 15,
fig. 1).

Pseudinvoluticeras douvillei SpaTH, 1925
Pl. 3, Figs. 3a—b, 5a—b; Pl. 4, Figs. 2a—b,
Text-Figs. 7a and 8.

1910 Simbirskites barbotanus DouvıLLE (non LAHUSEN),
p. 17, pl. 3, fig. 4a-b.

Simbirskites payeri DouvıLı£ (non TouLa), p. 18,
pl. 3, figs. 3a-b.

1925 Psendinvoluticeras douvillei SpaTH, p. 134 (sp. nov.)
(= S. barbotanus Douv. non LAHUSEN).
Pseudinvoluticeras decipiens SPATH, p. 134, (sp. nov.)
(= S. payeri Douv. non TouLa).

1931 Virgatosphinctes lotenoensis WEAVER, p. 423, pl. 48,
figs. 322, 323.

1954 Virgatosphinctes erinoides INDANs (non BURCKHARDT),
p. 109, pl. 15, fig. 1.

Material. — 14 specimens in general well pre-
served. S.G.N. 8904/1—3: three well preserved
phragmocones without body chamber. S.G.N. 8885/1:
fragment of body chamber. S.G.N. 8894/1: phrag-
mocone not well preserved, without body chamber.
S.G.N. 8903/1—3: three small phragmocones, well
preserved. S.G.N. 8912/3: small phragmocone frag-
ment. S.G.N. 8899/1—4: four phragmocones, poorly

Figure 7: Whorl sections of Virgatosphinctinae. a: Psendoinvoluticeras douvillei, S.G.N. 8904/1;
b: P. windhauseni, S.G.N. 8900/2; c: Virgatosphinctes mexicanus, S.G.N. 8883; d: V. andesen-
sis, S.G.N. 8894/2; e: V. denseplicatus rotundus, G.P.1.T. 1545/2; f: Pseudinvoluticeras (?)
wilfridi, S.G.N. 8898/1; g: V. evolutus n. sp., S.G.N. 8901/1 (Holotype); h: Choicensisphinctes
choicensis sutilis n. ssp., S.G.N. 8902/1 (Holotype); i: Ch. choicensis, S.G.N. 8905/3; j: Ch. eri-
noides, S.G.N. 8885/2; k: Pachysphinctes americanensis n. sp., S.G.N. 8952/1 (Holotype);
l: Subdichotomoceras araucanense n. sp., S.G.N. 8935/1 (Holotype); m: S. windhauseni, S.G.N.
8940/2; n: Aulacosphinctoides aff. A. hundesianus, S.G.N. 8934/1; o: Parapallasiceras sp. indet.,
S.G.N. 8942/2; p: P. aff. pseudocolubrinoides, S.G.N. 8947/1; q: P. aff. recticosta, S.G.N. 8942/5.
Natural size.

preserved. S.G.N. 8884/3: phragmocone fragment,
poorly preserved.

Description. — Medium size shell, inflated
and involute, with a whorl overlap ranging from
28 0/o to 30°/o with regard to the diameter of the
shell. The whorls are regularly higher than wide,
with a H/W ratio ranging from 1.06 to 1.10. The
whorl section is subtrapezoidal, but with rounded
periphery (text-fig. 7a). The maximum width is at the
umbilical border. The umbilicus is narrow and very
deep, and the umbilical slope, of diagnostic value, is
high and almost vertical. The flanks and the umbili-
cal slope form a rect angle with rounded border, and
they are slightly convex, converging to a gently
rounded periphery.

The internal whorls are somewhat depressed, and
therefore wider than high. Ornamentation is charac-
terized by fine, mostly biplicate ribs and to a lesser
proportion virgate ribs. Projected constrictions are
also present.

In the last whorl, particularly in the body chamber,
the ornamentation changes its aspect due to the forma-
tion of periumbilical swellings. In the last whorl
there is an average of 30 periumbilical primary ribs,
from which originate bundles containing 3 to 4 fine
ribs, the more anteriorly-situated being more prorsira-
diate, with the posteriorly-situated somewhat rursira-
diate. Between these bundles are intercalated secon-
dary ribs which reach the middle of the flank; the
shape of these ribs is similar to that of the primary
ribs. Both types of ribs cross the venter without inter-
ruption. The ribbing in the last part of the body
chamber becomes gradually smooth, until only the
umbilical swellings remain. In the last whorl there is
a total of about 110 primary and secondary ribs.

The suture line (text-fig. 8) is very elaborate; the L
lobe is slightly deeper than the E lobe. The E/L
saddle is higher and wider than the E/U saddle, and
both are asymmetrically divided by two accessory
lobes. There are also three elaborate U lobes (U,, U,
and U,).

2 L
Ei
A
{
|
I
l
I
ı
j
I
j
l
I

Figure 8: Suture line of Pseudinvoluticeras douvillei Sparn, S.G.N. 8904/2. X3.
Measurements. — (better-preserved speci- Specimen n° DI UT U/DER NEUN
mens only)

: n S!GINS 8903/28 4275312 7710:289 7229292 51:10
a EV VEN esosrshe 48% 1030 124 221., Al
“S. barbota- SIGN.L2 8899/17 7525.1552.02877220 72 —_
nus” Douv. 9325 03 - — — S:G-N.2 8899/4555372 2:1:10.0:298 5:15 7147107
“S. payeri” Dowv. 4 253 029 — — —

S.G.N. 8904/11 83 24 0.28 37 34 1.08 Remarks. — The material described here can
S.G.N. 8904/22 68 21 0.30 32 30 1.06 be included in the genus Pseudinvoluticeras SPaTH,
S.G.N. 8904/3 67 20 0.29 30 28 1.07 1925 (type species: P. somalicum SpaTH, 1925, pl. 15,
S.G.N. 8905/11 94 29 0.30 38 36 1.05 figs. 7a—c, text-fig. 10), but differs from the genotype
S.G.N. 8894/]1 72 21 029 31 29 1.06 in being slightly less involute and also less densely
S.G.N. 8885/11 97 28 0.28 45 42 1.07 ribbed. On the other hand, it strongly resembles
S.G.N. 8903/11 58 17 029 24 22 1.09 P. dowvillei Sparn, 1925 (= Simbirskites barbotanus

DouviL£ non LAHUsEn, 1910, p. 17, pl. 3, figs. 4a, b)
in all at its morphologic characteristics.

“P. decipiens” SpatH (1925, p. 134), based on “Sim-
birskites payeri” DouviLL£ non TouLA (1910, p. 18,
pl. 3, figs. 3a, b) is apparently cospecific with the
species douvillei of SpatH. In the original description
of “S. payeri”, Douviuı£ (1910, p. 18) stated that
“La forme generale, le profil de la coquille, la dimen-
sion de l’ombilic, les dimensions et disposition des
cötes ombilicales et externes chez l’adulte son tout &
fait comparables aux &lements correspondants de
P’espece que nous venons de rapporter A S. barbo-
tanus”. The essential difference which influenced
DouvILL£ to separate this “species” appears to be
“,..]a ornamentation tres caracteristique de la partie
jeune” (op. cit., p. 18). As can be seen in the speci-
mens figured by Douvirz£, the only ones he had
available for study, the internal whorls are impossible
to compare, because in the specimen of pl. 3, fig. 4a
they are entirely covered. Furthermore, “S. payerı”
has the test preserved only in the first fourth of the
last whorl, while “S. barbotanus” has it entirely pre-
served. This would explain the very slight differences
in the ornamentation of both specimens. The dif-
ferent U/D ratios (0.28 for “S. barbotanus and 0.29
for “S. payeri”) fall within the range of variation of
the species described here. It is for these reasons that
these two “species” are considered here to be cospeci-

fic.

As mentioned above, SpatH (1925, p. 134 and 142)
considered “S. barbotanus” DouviLL£ (non LAHUSEN)
as the type species of P. douvillei, and “S. payeri”
Douviu£ (non TouLa) as the type species of P. deci-
piens. On the basis of the analysis made above, and
retaining the name of P. douvillei because it is better
known and has priority in the paper by SrATH (op. cit.,
p- 134), it is clear that “S. payeri” falls into the syno-
nymic list of P. douvillei.

Another specimen that can also be included in
P. douvillei, as already suggested by SpatH (1950,
p. 115), is “Virgatosphinctes lotenoensis” WEAVER
(1931, p. 423, pl. 48, figs. 322, 323), found by WEAVER
6.5 km to the west of Cerro Lotena.

“Virgatosphinctes erinoides” InDAans non BURCK-
HARDT (1954, p. 109, pl. 15, fig. 1), from Portezuelo del
Burro, Mendoza, Argentina, can also be included in
P. douvillei SrarH. Inpans herself noted the strong
analogy between this form and “S. payeri” DouviLL£
and, in fact, it resembles much more P. douvillei than
the true “Perisphinctes” erinoides of BURCKHARDT
(1903, p. 51, pl. 8, fig. 1), a form much more evolute
that is included in this study in the new genus Choi-
censisphinctes.

P. mozambicum CoLıısGnon (1960, pl. 159, fig. 631)
differs from P. douvillei in being more involute and in
having weaker periumbilical swellings. Finally,

P. windhauseni (WEAVvER) has a more compressed shell
and is much more densely ribbed.

Occurence. — Lower part of the Vaca Muerta
Formation. Bed 2 of the Cerro Lotena section. Vir-
gatosphinctinae Beds. Occurs in association with
Virgatosphinctes andesensis, V. mexicanus, V. burck-
hardti, V. evolutus n. sp., V. denseplicatus rotundus,
P. windhauseni, P. (?) wilfridi, Choicensisphinctes
choicensis, Ch. choicensis sutilis and Ch. erinoides.

Age. — Uppermost Lower Tithonian. V. mendo-
zanus Zone.

Pseudinvoluticeras windhauseni (WEAVER, 1931)
n. comb.
Pl. 3, Fig. 2, 4a4—b; Text-Fig. 7b.

1931 Virgatosphinctes windhanseni WEAVER, p. 425, pl. 48,
figs. 324, 325.

Material. — 15 specimens, mostly fragments,
not very well preserved. S.G.N. 8900/1—10: phrag-
mocone fragments, poorly preserved. S.G.N. 8912/
1—2: two phragmocone fragments. S.G.N. 8884/2:
phragmocone fragment. S.G.N. 8893/1—2:
plete phragmocone, badly preserved.

incom-

Description. — Shell of medium size, slightly
inflated and involute. The diameter of umbilicus
ranges from 23 ®/o to 26 %/o of the whorl overlap. The
umbilicus is narrow and deep, and the umbilical wall
almost vertical; the flanks and the umbilical wall form
a rect angle with rounded border. The whorl section
is elliptical, with somewhat convex flanks converging
rapidly to a widely convex periphery (cf. text-fig. 7b).
The maximum width is at the umbilical border. In
the internal whorl the ornamentation is characterized
by very fine, regularly spaced ribs, which begin in the
umbilical wall, crossing it in a somewhat rursiradiate
direction. At the umbilical border, they gradually
turn towards the aperture; on the flanks they clearly
project and cross the venter without interruption.
Near the base of the middle third of the flank, the
ribs begin to bi- or triplicate, but maintain the same
prominence.

In the last part of the body chamber there is a ten-
dency towards formation of periumbilical swellings,
and also a gradual decrease in the prominence of the
ribbing, leading to the formation of smoother surfaces.

Because of the fragmentary preservation of the ma-
terial, the number of ribs could not be established
exactly; it is estimated as consisting of 50 primaries
and 130 secondaries. The poor preservation also pre-
cluded determination of the suture line.

Measurements. — (better preserved speci-
mens only)
Specimen n?° DI UT ZU/DIEIT WEIN
“V."windhauseni
WEAY: sspee.ne1l0 857 720°70.237 197 18.5771:02
SIGNS 18900/27495 2117 10227227207 ,1.10
SIG!N. 18900/377507 127 10.247 2272077 1.19
S.G.N. 8900/47 257140247 25° 197 1.31
SIGENZ 28900/5225 1E127°.0:237 72272207 71.10
S.G.N. 8900/6 30 7.0235 1375135 1:00
Remarks. — The coiling of the shell, narrow

and deep umbilicus, almost vertical umbilical slope,
and ribbing with a tendency to form periumbilical
swellings and smooth surfaces in the body chamber,
together suggest that the material can be included in
the genus Psendinvoluticeras.

Specifically, it shows very close correspondence to
“Virgatosphinctes” windhauseni WEAVvER (1931,
p. 425, pl. 48, figs. 324, 325), which was also found by
WEAVER in the Cerro Lotena area. Therefore, the
name P. windhauseni (WEAVER) n. comb. is proposed.

None of the species of Pseudinvoluticeras known to
date shows such fine and dense ribbing as the described
material. This characteristic is therefore considered to
be of diagnostic value.

“Virgatosphinctes” (Lithacoceras) tenuilineatus
Inpans (1954, p. 103, pl. 13, figs. 1, 2), contrary to the
view of DonzE & Enay (1961, p. 70), falls more pro-
perly in Psendinvoluticeras than in Lithacoceras, and
appears to be closely related to P. windhanseni.

Occurrence. — Lower part of the Vaca
Muerta Formation. Bed 2 of the Cerro Lotena section
(Virgatosphinctinae Beds), in association with Virga-
tosphinctes andesensis, V. mexicanus, V. burckhardti,
V. evolutus, V. denseplicatus rotundus, Psendinvoluti-
ceras douvillei, P. (?) wildfridi, Choicensisphinctes
choicensis, Ch. choicensis sutilis and Ch. erinoides.

Age. — Uppermost Lower Tithonian. V. men-

dozanus Zone.

Pseudinvoluticeras (?) wilfridi (DouviLı£, 1910)
Pl. 5, Figs. 3a—b; Text-Fig. 7f.

1910 Holcodiscus wilfridi DouviLz£, p. 12, pl. 2, fig. 6.

1954 Virgatosphinctes wilfridi (Douwvııı£t) — Inpans,
p- 107, pl. 13, fig. 3.
Material. — One specimen. S.G.N. 8898/1:

phragmocone well preserved, but internal whorls not
very apparent.

Description. — The shell is discoidal, small
and relatively involute. The umbilicus is narrow and
deep. The U/D ratio = 0.31. The whorls are
somewhat inflated and wider than high. The umbili-
cal wall is strongly inclined, almost vertical. The
umbilical wall and the flanks form a rectangle with
rounded edge. The flanks are subplanate and rapidly

converge to a widely-rounded periphery. The orna-
mentation is characterized by fine and dense ribbing.
The ribs commence in the umbilical slope, where they
are somewhat rursiradiate. At the umbilical border
they bend forward, describing a sigmoidal trajectory
over the flanks. The ribbing is characterized by dico-
tomic or virgatotomic branching at different heights
on the flanks. The branched ribs maintain the same
prominence as the primaries, and cross the venter
without interruption. In the last volution there are
three rather unclear constrictions, anteriorly bordered
by a simple rib and posteriorly by virgate bundles.
The suture line could not be detected.

Measurements —
DEZUSZ UVDZHZENZEEUN
8898/11 45 14

Specimen n?°

S.G.N. 0:31 1722217 20:80

Remarks. — The specimen, which consists of
the internal whorls of the phragmocone, is surpri-
singly similar to that figured as “Holcodiscus” wil-
fridi by Douvirı£ (1910, p. 12, pl. 2, fig. 6). This
species, coincidently, is also based on an incomplete
phragmocone which only shows the internal whorls.
The specimen figured by Inpans (1954, p. 107, pl. 13,
fig. 3) is also very similar. A problem arises as to
where this species should be generically placed, be-
cause its attribution to the genus Virgatosphinctes
Unis, as made by Inpans (1954) — perhaps influenced
by the words of Unis (191la, p. 542) — does not
appears to be acceptable. Although this species
resembles Virgatosphinctes of the denseplicatus group,
the similarity is only superficial because its whorl sec-
tion is somewhat more inflated, the umbilical slope is
almost vertical and the shell is more involute, all
features which are absent in Virgatosphinctes. The
enigmatic species wilfridi of DouviLı£ could also be
included either in the genus Aulacosphinctoides or
Pseudinvoluticeras. Umuic himself, in discussing the
inclusion of DouvıLı£’s species in his genus Virgato-
sphinctes, stated with regard to “V.” wilfridi that
“Vielleicht bildet diese Art das Jugendstadium des
Simbirskites payeri R. Douv.” UHric, 1911a, p. 542).
As mentioned above, “S. payeri” is actually included
in Pseudinvoluticeras.

In view of the lack of material, the specimen des-
cribed here is provisionally attributed to the genus
Psendinvoluticeras with interrogant, though bearing
in mind the problem outlined above.

Perisphinctes (Aulacosphinctes) wilfridi BURcK-
HARDT non Douviuz£ (1921, p. 51, pl. 17, figs. 1—3)
has no relation to the form described here and is pro-
bably an Aulacosphinctoides (cf. Sparn, 1927—33,
p- 533).

Occurrence. — Lower part of the Vaca
Muerta Formation. Bed 2 of the Cerro Lotena sec-

tion (Virgatosphinctinae Beds), in association with
V. andesensis, V. mexicanus, V. burckhardti, V. evolu-
tus, V. denseplicatus rotundus, P. douvillei, P. wind-
hauseni, Ch. choicensis, Ch. choicensis sutilis and Ch.
erinoides.

Age. — Uppermost Lower Tithonian. V. men-

dozanus Zone.

Genus VIRGATOSPHINCTES Unuiıg, 1910

Type species. — Perisphinctes (Virgato-
sphinctes) broilii UnHuıc, 1910, p. 336, pl. 91, figs.
la—d. SDR. Douvirı£, 1910a, p. 737.

The controversial and variable genus Virgato-
sphinctes, which was originally described by UHris
(1910) from the Spiti Shales of India, has been the
subject of much discussion, and, until recently, its
presence in the Andean domain has not been fully ac-
cepted (cf. R. Enay, 1972, p. 374).

Before beginning any analysis of the problem, it is
worthwhile to recall the words of Unric himself in
the introduction of his subgenus Virgatosphinctes,
stating that “...In no other group is the variability
so great as in the present one; every character under-
goes an almost incredible degree of fluctuation.
Hardly a single specimen resembles another one in
every detail...” (Unric, 1910, p. 308). Although
Virgatosphinctes was immediately typified by R. Dov-
vıLL£ (1910a, p. 737), who designated V. broilii
UHuiG as the type species, the words of Unric did not
lost their import to those dealing with this polifacetic
genus, and were reiterated by SpatH (1927—33, p. 532
and followings) in his description of the Jurassic
cephalopod fauna of Cutch.

It should be noted that Ustig himself (1910, p. 312,
1911a, 1911b) had suggested that many of the forms
previously figured as Virgatites by BuURCKHARDT (1903)
could be included in the genus Virgatosphinctes,
though this point of view was strongly rejected by
BURCKHARDT (1911a, 1911b, 1930).

Although the Andean Virgatosphinctes appears to
be a group with variable characteristics (cf. STEIGER,
1914, p. 497 and following), most specimens clearly
display the diagnostic features of this genus. In any
case, it is not reasonable to refute the presence of
Virgatosphinctes in the Andean Tithonian if such Hi-
malayan forms as Aulacosphinctoides, Torguati-
sphinctes, Aulacosphinctes, Himalayites and Subdicho-
tomoceras are accepted without reservation. The
Cerro Lotena section ha yielded several examples of
Virgatosphinctes, represented by the species V. ande-
sensis, V. mexicanus, V. burckhardti, V. denseplicatus
rotundus and V. evolutus n. sp., which are described
below.

It is also worth noting that affinities exist between
Virgatosphinctes and Subplanites. As stated by the

author who defined the latter genus “the resemblances
of this group with the true Virgatosphinctes is often
close” (SparH, 1925, p. 120). However, when SparH
established the genus Subplanites (type species: Virga-
tosphinctes reisi SCHNEID, 1914, p. 163, pl. 6, fig. 2), he
did not give an adequate diagnosis and therefore it
was the subject of much misinterpretation among later
authors. SpaTH himself, while describing the Jurassic
fauna of Cutch, stated that the forms described under
Subplanites (v. gr. S. elegans, S. adeloides, S. ? fle-
xnosus) “are more closely allied to Perisphinctes con-
tiguus (ZiTTEL) UHLic” (SpatH, 1927—33, p. 468)
than to the typical reisi-schlosseri-subdanubiensis
group of Neuburg, “...but the frequent confusion
of contiguns-like species of Subplanites with the true
Virgatosphinctes shows that the two genera are closely
similar at certain stages””.

More recently, HÖLDER (in BERCKHEMER & HÖLDER,
1959, p. 51) placed Virgatosphinctes reisi SCHNEID, the
type species of Subplanites, in the synonymic list of
Perisphinctes (Virgatosphinctes) rupellianus. The
cited examples clearly show that the two genera are
closely related.

Although many specimens from Cerro Lotena
resemble Subplanites, it appears more reasonable to
include them in Virgatosphinctes on the basis of (1):
whorl section, which is subeircular and somewhat de-
pressed in most cases, a feature atypical of Subplani-
tes, and (2): suture line, which is relatively simple in
contrast to that of Subplanites, where the accessory
lobe dividing the E/U saddle is strongly oblique and
the U lobes are much more elaborate.

For the above reasons, the present author includes
some specimens from Cerro Lotena in the genus Vir-
gatosphinctes, though bearing in mind its close affini-
ties with the genus Subplanites.

Virgatosphinctes mexicanus (BURCKHARDT, 1906)
Pl. 2, Figs. 1a—b; Text-Fig. 7c.

1906 Virgatites mexicanus BURCKHARDT, p. 115, pl. 31,
figs. 5-9.

1910 Virgatites mexicanus BURCKHARDT — DOUVILLE, p. 8,
pl. 1, figs. 1-2.

1954 Virgatosphinctes mexicanus (BURCKHARDT) — INDANS,
p- 113, pl. 18, fig. 1.

Material. — One specimen. S$.G.N. 8883:
phragmocone fragment with remains of body chamber.

Description. — Discoidal shell, rather evo-
lute, with the whorls overlapping the external third of
the flanks of the precedents. U/D ratio = 0.44.
Whorl section subelliptical, somewhat higher than
wide (text-fig. 7c). Umbilical slope inclined, umbilical
border rounded, with slightly convex flanks converg-
ing to a rounded periphery. The umbilicus is wide
and relatively deep. Ribbing on the internal whorls,
with probable bifurcation at the external third of the

flank. In the last whorl the ribbing becomes vir-
gatomous. The virgate ribs commence at different
heights on a projected primary rib; a further division
occurs at a level somewhat higher on the flanks. Con-
strictions are also present, and are prorsiradiate, and
anteriorly-bordered by a stronger rib. The suture line
could not be observed.

Measurements. —
Specimen n° D U VD HH W HXNW
S.G.N. 8883 95 42 044 31 28 1.10

Remarks. — All of the described morphologi-
cal characteristics agree with those of the genus Vir-
gatosphinctes Unis (1910). Specifically the specimen
strongly resembles Virgatosphinctes mexicanus
(BURCKHARDT, 1906, p. 115, pl. 31, figs. 5—9).

The specimens figured by Douvırı£ (1910, p. 8,
pl. 1, figs. 1, 2) and Inpans (1954, p. 113, pl. 18, fig. 1)
from the provinces of Neuqu&n and Mendoza, re-
spectively, belong without doubt to BURCKHARDT’s
species, though the specimens from Neuquen are
somewhat more densely ribbed in the internal whorls.

Occurence. — Lower part of the Vaca Muerta
Bed 2 of the Cerro Lotena section (Vir-
gatosphinctinae Beds), in association with V. andesen-
sis, V. burckhardti, V. evolutus, V. denseplicatus
rotundus, P. douvillei, P. windhauseni, P. (?) wilfridi,
Ch. choicensis, Ch. choicensis sutilis and Ch. erinoides.

Formation.

Age. — Uppermost Lower Tithonian. V. men-

dozanus Zone.

Virgatosphinctes andesensis (DouvıLı£, 1910)
Pl. 2, Figs. 5a—b; Text-Figs. 7d and 9.

1910 Virgatites andesensis DouviL£, p. 17, pl. 1, figs. 3a-b,

4a-f.
1931 Virgatosphinctes andesensis (DouvıLL£) — WEAVER,
p. 422, pl. 47, figs. 313, 314; pl. 48, figs. 318—321.
1954 Virgatosphinctes andesensis (DouvıLL£) — Inpans,

p- 111, pl. 13, fig. 9; pl. 16, figs. 1—5.
1958 Virgatosphinctes andesensis (DOUVILLE) — CORVALÄAN,
p- 43, pl. 8, figs. 18a, b.

----- k---->

Figure 9:

Material. — One specimen. $.G.N. 8894/2:
phragmocone well preserved, with two thirds of the
last whorl belonging to the body chamber. One side
somewhat deteriorated and crushed.

Description. — Discoidal shell, evolute. U/
D ratio = 0.41. Whorl section suboval, somewhat
higher than wide (text-fig. 7d). Umbilical slope
strongly inclined, umbilical border rounded with
slightly convex flanks converging to a rounded peri-
phery. The body chamber occupies two thirds of the
last whorl. 'The ornamentation is well defined, and
composed of prominent primary ribs that commence
near the base of the umbilical slope, where they are
somewhat rursiradiate. At the umbilical border they
become narrow and more prominent, crossing the
internal part of the flank prorsiradiately and the
external part radially. The ribs display a slight
inflection in the middle part of the flank. There is
also a virgatotomic branching of the ribs at different
heights on the flanks. A given rib can be divided into
two in the lower part of the flank. A further division
occurs at a level somewhat higher on the flanks, as
was described by Uhric (1910, p. 306) in his diagnosis
of Virgatosphinctes. This type of division becomes
more evident towards the aperture of the shell, parti-
cularly at the body chamber. In the phragmocone, it
is more common to find bi- or trifurcate ribs. The
virgate ribs situated anteriorly project strongly, while
the posterior ones are radial or somewhat rursiradiate.
There are also intercalatory ribs which disappear on
the internal third of the flank. The virgate and inter-
calatory ribs cross the venter without interruption. In
the last whorl there are 42 primary ribs and 107 se-
condary ribs on the periphery. In the body chamber
a nitid constriction is present which is first projected
and then radial, and which is anteriorly bordered by a
fine, prominent rib.

The suture line (text-fig. 9) has E and L lobes of the
same depth, the F/L saddle is wider than the E/U
saddle and there are two somewhat oblique U lobes of
decreasing depth.

L U,

Suture line of Virgatosphinctes andesensis (Douv.), S.G.N. 8894/2. X3.

Measurements —
Specimen n° D’ "U "U/DF 7 TIW SE/W

S.G.N. 88942 96 40 041 33 31 1.06
Remarks. — On the basis of the diagnosis of
Virgatospbhinctes (cf. Douvirı£, 1910a, p. 737;

ARKELL et al., 1957, p. L 330), the specimen can be
assumed to belong to this genus. The whorl section,
rate of whorl overlap, umbilical slope, and the rib-
bing characterized in the internal whorls by bi- or tri-
cotomic branching and in the external ones by virgato-
tomic branching as described by UHtic, indicate that
the specimen can unquestionably be included in the
genus Virgatospbhinctes.

Specifically, it closely resembles V. andesensis
(Dovvir£, 1910, p. 17, pl. 1, figs. 3a—b; 4a—f),
but it resembles even more the specimens attributed to
the same species by WEAvER (1931) and Inpans (1954),
in whose respective illustrations a rather notable va-
riability in the ornamentation can be observed. In
the described specimen, as well as in those figured by
the above authors, the umbilicus is somewhat nar-
rower than that of the larger specimen of DouviLL£
(1910, pl. 1, fig. 3a), though this difference may be
only an apparent one because the umbilical border of
the Douvirı£ species is partially covered by matrix
which prevents observation of the line of coiling. The
specimen of this study is almost identical to that fig-
ured by Weaver (1931, pl. 47, figs. 313 and 314),
which also comes from Cerro Lotena.

“Virgatosphinctes” sanchezi VERMA & WESTERMANN
(1973, p. 185, pl. 32, pl. 33, pl. 34, fig. 2, text-fig. 15)
from the Tithonian of Sierra Catorce, Mexico, has an
inverted ontogeny with regard to Virgatosphinctes,
showing transposed stages of ornamentation, that is,
virgate ribs occur in the young stage while simple and
bipartite ribs are present in the adult stage.

Occurrence. — Lower part of the Vaca
Muerta Formation. Bed 2 of the Cerro Lotena section
(Virgatosphinctinae Beds), in association with V. me-
xicanus, V. burckhardti, V. evolutus, V. denseplicatus
rotundus, P. douvillei, P. windhauseni, P. (?) wilfridi,
Ch. choicensis, Ch. choicensis sutilis and Ch. erinoides.

Age. — Uppermost Lower Tithonian. V. mendo-
zanus Zone.

Virgatosphinctes burckhardti (DouviLL£ 1910)
Pl. 5, Figs. 2a—b.

1903 Virgatites aff. Quenstedti BURCKHARDT (non RoviLr),
p- 42, pl. 6, figs. 104.

1910 Virgatites Burckhardti DouviLLE, p. 10 (sp. nov.).

1910 non Perisphinctes (Virgatosphinctes) Burckhardti
Unuiıg, p. 332, pl. 62, figs. 3a-c.

1954 Virgatosphinctes (Lithacoceras ?) burckhardti (Dou-
VILLE) — InDans, p. 103, pl. 13, figs. 4—5.

Material. — One specimen. $.G.N. 8896/1:
well-preserved incomplete phragmocone, with remains

of body chamber.

Description. — Medium size shell, moder-
ately evolute. U/D ratio = 0.35. Whorl section
depressed, with the maximum width at the umbilical
border. Umbilical slope strongly inclined, umbilical
border rounded and flanks slightly convex, converging
to a widely rounded periphery. The ornamentation
is fine, densely ribbed and typically virgate. The
primary ribs commence at the umbilical seam, and
cross the umbilical slope rursiradiately. At the umbi-
lical border they become stronger, and on the flanks
they are prorsiradiate. In the internal third of
the flank, the ribs shows virgatotomic branching,
resulting in new divisions in the upper third of the
flanks. In the last half of the last whorl there are
21 primary ribs at the umbilical border and 72 secon-
daries on the periphery. All the ribs cross the venter
without interruption. Constrictions are usually pre-
sent, following the direction of the ribbing. They are
generally anteriorly bordered by a single rib. The
suture line could not be observed.

Measurements —
Specimen n?° DU WU/D? IAZSNGEEN
S:G.N. 8896/11 57 20 035 21 257 0:84

Remarks. — The specimen coincides in its mor-
phological characteristics with the genus Virgato-
sphinctes Unuig. Specifically, it shows close aflinities
with V. burckhardti (Douvirı£, 1910, p. 10), which
is based on “Virgatites aff. quenstedti” BURCKHARDT
non RouırL (1903, p. 42, pl. 6, figs. 1—4). The spec-
imen figured by Inpans as Virgatosphinctes (Lithaco-
ceras ?) burckhardti (see synonymic list) also coincides
with the described specimen.

V. densistriatus (STEUER, 1897, p. 62, pl. 15, figs. 8
to 10) differs in its less evolute shell and more distant
primaries. Also V. denseplicatus (WAAGENn, 1875,
p. 201, pl. 45, figs. 3a—b; pl. 55, figs. 1a—b) is also
a closely similar form, but differs in its larger evolu-
tion and denser, less prominent ribbing. V. haughtoni
SparH (1927—33, p. 534, pl. 77, fig. 6) from Madagas-
car and “Perisphinctes” aguilari BURCKHARDT (1906,
p- 110, pl. 27, figs. 6—9) from Mexico are also close
species, but they differ from V. burckhardti in its less
vigorous primaries, which are more distant and less
projected.

It is worth noting that “Perisphinctes” (Virgato-
sphinctes) burckbardti Unis (1910, p. 332, pl. 62,
figs. 3a-c) is a species which is more closely allied to
Subplanites, and does not belong to the DouvirL£
species described here.

Occurence. — Lower part of the Vaca

Muerta Formation. Bed 2 of the Cerro Lotena section

(Virgatosphinctinae Beds), in association with V. me-
xicanus, V. andesensis, V. evolutus, V. denseplicatus
rotundus, P. douvillei, P. windhauseni, P. (?) wilfridi,
Ch. choicensis, Ch. choicensis sutilis and Ch. erinoides.

Age. — Uppermost Lower Tithonian. V. men-

dozanus Zone.

Virgatosphinctes denseplicatus rotundus SpatH, 1931
Pl. 2, Figs. 2 and 3; Text-Fig. 7e.

1931 Virgatosphinctes denseplicatus (WAAGEN) var. rotunda
SPATH — in SPATH, 1927-33, p. 532, pl. 96, figs. 3a-b;
pl. 102, fig. 4.

1954 Virgatosphinctes cf. denseplicatus (WAAGEN) var. ro-
tunda SpATH — INDANS, p. 106, pl. 21, fig. 1.

Material. — Two specimens. S.G.N. 8905/1:
well preserved phragmocone, with the last part of the
last whorl somewhat crushed. G.P.1.T, 1545/2: very
well preserved phragmocone.

Description. — The shell is discoidal and
rather small. Umbilicus relatively narrow but not
deep. U/D ratio = 0.35 to 0.39. Umbilical slope
strongly inclined, umbilical border rounded, and
flanks gently convex, gradually converging to a
rounded periphery. Whorl section subelliptical and
somewhat wider than high (text-fig. 7e). Ornamen-
tation dense and formed of fine ribs that commence in
the middle of the umbilical slope; in the flank they are
somewhat prorsiradiate and they cross the periphery
without interruption. Virgatotomic and dicotomic
branching of the ribs occurs in the last whorl. Con-
strictions are also present, and are anteriorly bordered
by a rib of similar prominence to the others. The su-
ture line could not be observed.

Measurements —

Specimen n?° DE AUESU/DEE HR ENEENNV

SIG.N.2228905/12 257220720357 724 7 —
G.BAT-IEE 1545/20 4671871039) 2 197 3217 2 0:99
Remarks. — In shape the described specimen

closely resembles V. denseplicatus (WAAGEn, 1875,
p- 201, pl. 46, figs. 3a, b; pl. 55, figs. 1a, b), and cor-
responds exactly to the variety rotundus of SparH
(1931, p. 532, pl. 96, figs. 3a, b; pl. 102, fig. 4). Spark
stated that “It is possible that this variety also includes
the inmature form figured in Pl. 102, fig. 4, although
its umbilicus is somewhat too narrow” (SparH, 1927
to 33, p. 533). The specimen described in this study
appears to be identical to this inmature form referred
to by SPATH.

V. denseplicatus (WAAGEN) from west Pakistan,
figured by Farmı (1972, p. 346, pl. 9, figs. 1a—b),
also closely resembles the described material.

V. densistriatus (STEUER, 1897, p. 63, pl. 15, figs. 8
to 10) also resembles this variety, although it was sug-

gested by SparH (1927—33, p. 534) to be a Pseudo-
virgatitid.

Occurrence. — Lower part of the Vaca
Muerta Formation. Bed 2 of the Cerro Lotena section
(Virgatosphinctinae Beds), in association with V. me-
xicanus, V. andesensis, V. burckhardti, V. evolutus,
P. douvillei, P. windhauseni, P. (?) wilfridi, Ch. choi-
censis, Ch. choicensis sutilis and Ch. erinoides.

Age. — Uppermost Lower Tithonian. V. men-

dozanus Zone.

Virgatosphinctes evolutus n. sp.
Pl. 5, Figs. 44—c; Text-Fig. 78.

1903 Perisphinctes aff. transitorins BURCKHARDT (non OP-
PEL), p. 40, pl. 5, figs. 4-9.
Perisphinctes contiguus BURCKHARDT (non CATULLO),
p- 38, pl. 4, figs. 7—10.

1931 Aulacosphinctes cf. A. transitorius (OPPEL) — WEAVER,
p- 415, pl. 45, fig. 306.

Holotype. — Virgatosphinctes evolutus
H. LEANZA n. sp., figured in Pl. 5, Figs. 4a—c, Text-
Fig. 7g of this paper. S.G.N. 8901/1.

Locus typicus. — Southern slope of Cerro
Lotena, province of Neuquen, Argentina.

Stratum typicum. — Lower part of the
Vaca Muerta Formation. V. mendozanus Zone.

Derivatıo nominis. — From the evolute
character of the shell.

Diagnosis. — Shell strongly evolute, with
whorl section subeircular, somewhat depressed. Or-
namentation in the internal whorls consists of elevated
and narrow biplicate ribs; in the outer whorls these
become gradually triplicate and virgatotomic. Con-
strictions are present. Suture line with trifid L lobe of
almost the same depth as the E lobe. The E/L and
E/U saddles are not very elaborate and are separated
by small lobes into two asymmetrical saddles. There
are also two U lobes which are somewhat oblique and
not very elaborate.

Material. — One specimen. S.G.N. 8901/1:
well preserved phragmocone with body chamber,
which occupies almost half of the last volution.

Description. — The shell is discoidal and
evolute. U/D ratio = 0.43. The last whorl section
is subeircular and somewhat depressed (cf. text-
fig. 7g). The periphery is slightly convex, the flanks
are very gently convex, the umbilical border is very
well rounded, and the umbilical slope is modertely
inclined. Almost half of the last whorl belongs to the
body chamber. The phragmocone is composed entire-
ly of calcite which has eliminated all traces of the
suture line except that limiting with the body chamber,

which is fossilized in limestone. The last volution con-
tains 49 primary ribs which commence at the umbilical
slope, where they are rursiradiate. They bend
forward on the umbilical border, and are prorsiradiate
on the flanks. In the portion of the last whorl cor-
responding to the phragmocone, almost all the pri-
mary ribs are divided in two branches, both of the
same prominence. In this portion, two or three inter-
calatory ribs are also preserved, which extend from
the external part of the shell to the middle of the
flanks.

There are also two examples of virgatotomic
branching which are limited anteriorly by constric-
tions. In the portion of the whorl belonging to the
body chamber, numerous virgate and triplicate exam-
ples of ribbing are observed, but only one case of
bifurcation is present, located at the beginning of the
body chamber. Three nitid constrictions are also
present in this portion of the volution; they are limited
anteriorly by a single rib and posteriorly by trifurcate
or virgate ribs.

The suture line, preserved in a septum linking with
the body chamber, shows a trifid L lobe of almost the
same depth as the E lobe. The E/L and E/U saddles
are not very elaborate and are separated by small
lobes into two asymmetrical saddles. There are also
two U lobes which are somewhat oblique and not very
elaborate.

Measurements.—
Specimen n° DU UDTZ HS W ENW
SG.N: 8901/1106 46 0.437 3538, 092

Remarks. — This new species is closely related
to Perisphinctes af. transitorius BURCKHARDT (non
Orrer) (1903, p. 40, pl. 5, figs. 4—9) and Perisphinc-
tes contiguus BURCKHARDT (non CATULLO) (1903, p. 38,
p- 4, figs. 7—10), both from Casa Pincheira, southern
Mendoza, Argentina. It differs only in its more
depressed whorl sections, perhaps because they repre-
sent younger ontogenetic stages. Therefore, these two
species are included in the synonymic list.

It is possible that “Aulacosphinctes” cf. transito-
rins WEAVER (non Opper) (1931, p. 415, pl. 45, fig. 306)
also belongs to the newly-described species.

“Perisphinctes aff. pseudolictor” CHoFFAT (BURCK-
HARDT, 1903, p. 36, pl. 5, figs. 1—6), later renamed by
SpAatH as Subplanites malargüensis, is a form super-
ficially similar to V. evolutus n. sp. differing only in
its more compressed whorls and its more elaborate
suture line.

With regard to the evolute Virgatosphinctes des-
cribed by Unrig from the Spiti Shales, V. evolutus
n. sp. strongly resembles V. haydeni Unis (1910,
p- 334, pl. 61, figs. 2a, d). With respect to the species
from Madagascar, V. rouselli CoLLiGnon (1960, pl.157,
fig. 630) it is the closer related species.

Occurrence. — Lower part of the Vaca
Muerta Formation. Bed 2 of the Cerro Lotena sec-
tion (Virgatosphinctinae Beds), in association with
V. andesensis, V. mexicanus, V. burckhardti, V. dense-
plicatus rotundus, P. douvillei, P. windhauseni, P. (?)
wilfridi, Ch. choicensis, Ch. choicensis sutilis and
Ch. erinoides.

Age. — Uppermost Lower Tithonian. V. men-

dozanus Zone.

Genus CHOICENSISPHINCTES nov.

Type species. — Perisphinctes choicensis
BURCKHARDT, 1903, p. 50, pl. 6, figs. 10—12; pl. 8,
fig. 6.

Diagnosis. — Discoidal, somewhat inflated
and rather evolute shell. Whorl section subtrapezoi-
dal, with rounded borders, wider than high. Orna-
mentation of the internal whorls regularly biplicate.
Outer whorls display strong, prominent and projected
primary ribs. Periumbilical swellings originate from
bundles of 4 to 10 fine equally spaced, somewhat pro-
jected secondary ribs which cross the venter without
interruption. No virgatotomic branching occurs.
Constrictions are present. Suture line has trifid L lobe
as deep as E, and E/L saddle wider and higher than
E/U saddle. Two U lobes are present which are very
simple and not oblique.

Locus typicus. — Area between Cajön del
Burro and the Choica-River valley, at the beginning
of the Rio Grande river, Mendoza province, Argen-
tina.

Stratum typicum. — Lower part of the
Vaca Muerta Formation. V. mendozanus Zone.

Derivatio nominis. — After the species of
BURCKHARDT, P. choicensis, which is itself named after
the Choica River, its locus typicus.

Discussion. — Choicensisphinctes gen. nov. is
here proposed to include those ammonites having an
inflated and rather evolute shell of olcostephanid
aspect, and ornamentation characterized by bundles of
4 to 10 ribs. These forms constitute an homogeneous
stock including the species “P.” choicensis, “P.” eri-
noides and “P.” aff. erinus of BURCKHARDT (1903).
It is worth recalling that Unis himself (1911a, p. 542)
had already suggested that the cited species of
BURCKHARDT could be grouped as a determinate group
of ammonites.

With regard to “P.” choicensis, Douvirı£ (1910a,
p. 738) stated that it could not be placed in the so-
called Andean Virgatites, which was later transferred

to Virgatosphinctes. Moreover, UHtiG (1910, p. 336)
pointed out that BURCKHARDT’s species could be dif-
ferentiated from his genus Virgatosphinctes (v. gr.
V. krafti UnLıc) “by its narrower umbilicus, trapezoid
cross section, simpler suture and much more numerous

branch ribs”.

The species erinoides of BURCKHARDT (1903, p. 51,
pl. 8, figs. 1—4) was included successively in the
genera Olcostephanus (BURCKHARDT, 1930, p.111, 112),
Aulacosphinctes (WEAVER, 1931, p. 417), Pararasenia ?
(SpatH, 1927—33, p. 469) and Virgatosphinctes
(Inpans, 1954, p. 109), but none of these generic
attributions appears to be plausible. However, as
shown below, it can probably be included in Choicen-
sisphinctes.

Finally, P. aff. erinus (D’Ors.) BURCKHARDT (1903,
p-. 52, pl. 9, figs. 1—2; pl. 8, fig. 5), which was later
renamed by BurckHarpr himself (1930, p. 110) as
Craspedites limitis, probably incorrectly, can also be
included more properly in Choicensisphinctes.

Choicensisphinctes gen. nov. differs from Virgato-
sphinctes UHLig, 1910 (type species: V. broilii Uni,
Sp Douvirı£, 1910a), in addition to the differences
already pointed out by UnHtic, in its more inflated
shell, its strongly inclined umbilical wall, and the
absence of virgatotomic branching.

The genus Pseudinvoluticeras SpaTH, 1925 (type
species: P. somalicum SpATH, 1925) in some cases shows
a similar ornamentation, but it is always more invo-
lute.

Choicensisphinctes therefore represents a transi-
tional form between Virgatosphinctes and Pseudinvo-
luticeras: it exhibits the coiling of the former, but an
ornamentation more similar to the latter.

Other genera which show close affinities with
Choicensisphinctes gen. nov. are Sublithacoceras, Pha-
nerostephanus and Usseliceras. Sublithacoceras
SpATH, 1925 (type species: Perisphinctes penicillatus
ScHneip, 1915) is much more compressed and shows a
tendency towards smooth surfaces in the body
chamber. The suture line is also much more elaborate.
Phanerostephanus SpaTH, 1950 (type species: P. sub-
senex SpATH, 1950) is more involute and displays
periumbilical swellings without ribbing in the last
whorls. Finally, Usseliceras Zeıss, 1968 (type species:
U. franconicum Zeıss, 1968), from south Franconia
area, is very similar with regard to the ornamentation,
but differs in being much more compressed, with
whorls higher than wide.

Occurrence. — Very common in the basal
beds of the Vaca Muerta Formation within the
Neuquen and Mendoza basin. Bed 2 of the Cerro
Lotena section (Virgatosphinctinae Beds).

Age. — Lower Tithonian. V. mendozanus Zone.

Choicensisphinctes choicensis (BURCKHARDT, 1903)
Pl. 2, Figs. 44—b; Text-Fig. 7i.

1903 Perisphinctes choicensis BURCKHARDT, p. 50, pl. 6,
figs. 10-12; pl. 8, fig. 6.

1931 Aulacosphinctes cf. A choicensis (BURCKHARDT) —
WEAVER, p. 414.

1954 Virgatosphinctes cf. raja Unis — Inpans, p.110,
pl. 14, fig. 1-3.

Material. — One specimen. $.G.N. 8905/3:
phragmocone with remains of body chamber, very
well preserved.

Description. — Discoidal shell of medium
size, moderately inflated and rather evolute. U/D
ratio = 0.36. Whorl section subtrapezoidal with
rounded borders, a little wider than high (text fig. 7i).
The maximum width occurs at the umbilical border.
The umbilical slope is strongly inclined, the umbilicus
wide and rather deep.

The flanks are gently convex and rapidly converge
to a rounded periphery. The ornamentation is cha-
racterized by strong and projected primary ribs that
show small radial periumbilical swellings which are
more pronounced near the aperture. In the last volu-
tion there are 28 to 32 primaries, each of which gives
rise to bundles of 4 to 7 secondary ribs, all having the
same prominence and an equal spacing. The ribs are
somewhat prorsiradiate, especially those more ante-
riorly situated, and cross the periphery without inter-
ruption. In the last whorl there are constrictions, two
of which are very clear; these are anteriorly bordered
by a more prominent and projected simple rib, and
posteriorly bordered by the more anterior of the
secondary ribs. The suture line has a trifid L lobe as
deep as E, with an E/L saddle wider and higher than
the E/U saddle. There are also two U lobes which
are very simple and not oblique (see BURCKHARDT,
1903, pl. 6, fig. 12).

Measurements. —
Specimen n?° DIAUSZUDESEISEINDEENW

Ch. choicensis
(Burck., 1903) 78 29
S.G.N. 8905/3 66 24

Remarks. — The described specimen cor-
responds exactly to “Perisphinctes” choicensis
BURCKHARDT (1903, p. 50, pl. 6, figs. 10—12; pl. 8,
fig. 6), which is the type species of Choicensisphinctes
gen. nov. It is very probable that “Aulacosphinctes”
cf. “A.” choicensis, described by WEAvER (1931,
p. 414) belongs to the species described here. This
form also comes from Cerro Lotena (WEAVER, op. cit.,
p. 415). On the other hand, “Virgatosphinctes” cf.
raja Inpans non Unuic (Inpans, 1954, p. 110, pl. 14,
figs. 1—3), from southern Mendoza, Argentina, shows

0.32.3234
03677247726

0.94
0.92

the morphological characteristics of Choicensisphinc-
tes in terms of ornamentation and whorl shape.

Parapallasiceras ? Danubisphinctes ? n. sp., Iydi-
stratiforme Zeıss (1968, p. 110, pl. 20, fig. 1), com-
pared by Zeıss (Op. cit., p. 115) to Virgatosphinctes
cf. raja Inpans (non UHLic), appears to be very closely
related to Choicensisphinctes.

Occurrence. — Lower part of the Vaca
Muerta Formation. Bed 2 of the Cerro Lotena section
(Virgatosphinctinae Beds), in association with V. an-
desensis, V. mexicanus, V. burckhardti, V. denseplica-
tus rotundus, V. evolutus, P. dowvillei, P. windhauseni,
P. (?) wilfridi, Ch. choicensis sutilis and Ch. erinoides.
Ch. choicensis is the commonest species found at the
base of the Tithonian transgression within the
Neuquen and Mendoza basin. It had been found by
the author in the sections of Cerro Lotena, Picun
Leufü, Mallin de los Caballos, Mallin Quemado,
Cajon de Almaza (Neuquen province), Bardas
Blancas and Arroyo Cieneguitas (Mendoza province).

Age. — Uppermost Lower Tithonian. V. men-

dozanus Zone.

Choicensisphinctes choicensis sutilis n. ssp.
Pl. 3, Figs. 1a—b, Pl. 4, Fig. 3; Text-Fig. 7h.

Holotype. — Choicensisphinctes choicensis
sutilis H. LEANZA n. ssp., figured in Pl. 3, Figs. 1a—b
of this paper. S.G.N. 8902/1.

Paratype. — Choicensisphinctes choicensis su-
tilis H. LEAnZA n. sp., figured in Pl. 4, Fig. 3 of this
paper. S.G.N. 8902/2.

Locus typicus. — Southern slope of Cerro
Lotena, province of Neuqu£n, Argentina.

Stratum typicum. — Lower part of the
Vaca Muerta Formation. V. mendozanus Zone.

Derivatio nominis. — After the fine and
elegant ribbing.

Diagnosis. — Shell discoidal, somewhat evo-
lute, with wide umbilicus and strongly inclined umbi-
lical slope. Whorl section subquadrangular, and as
high as wide. Ornamentation in the internal whorls
composed of very fine and dense ribbing, mostly with
dicotomic branching. In the outer whorls are strong
and somewhat irregularly-spaced and projected pri-
mary ribs, with periumbilical swellings which arise
from bundles of 5 to 9 fine and projected secondary
ribs. Constrictions are present.

Material. — Two specimens. $.G.N. 8902/1:
phragmocone with remains of body chamber, very
well preserved, but lacking the test (Holotype).
S.G.N. 8902/2: phragmocone fragment and body
chamber, laterally crushed (Paratype).

Description. — Discoidal and somewhat
evolute shell. U/D ratio = 0.36. The umbilicus is
wide and rather deep. The whorl section (text-fig. 7h)
is subquadrangular, and as high as wide. 'The umbili-
cal slope is strongly inclined. The internal whorls are
ornamented by fine and elevated ribs which are very
densely spaced, most of them with dicotomic branch-
ing. In the last whorl the ribs commence in the mid-
dle of the umbilical wall, where they are rursiradiate.
At the umbilical border they bend forward, pro-
ducing periumbilical swellings. In this whorl there
are an average of 40 primary ribs. In the internal
third of the flank there is a branching into bundles
composed of 5 to 9 secondary ribs, all of which have the
same prominence, being more projected the more an-
teriorly situated ribs. All the ribs cross the periphery
without interruption. Between two contiguous bun-
dles of ribs are intercalatory ribs which, except where
they disappear in the upper third of the flank, have
the same prominence as the rest of the ribbing. Three
constrictions occur in the last whorl; they are prorsi-
radiate and limited anteriorly by a single prominent
rib and posteriorly by the more anterior of the secon-
dary ribs. The body chamber occupies more than half
the last whorl, and the aperture shows a projected
lappet at the height of the middle third of the flank.
The suture line could not be detected.

Measurements. —

Specimen n° Du "U EU/DT EL SW ENM
S.G.N. 8902/11 71 26 036 28 28 1.00
SIG.N. * 8902/27 7927 3310.35 3 —_

Remarks. — The material agrees in its morpho-
logical characteristics with the genus Choicensisphinc-
tes, but differs from its type species Ch. choicensis
(BURCKHARDT, 1903, p. 50, pl. 6, figs. 10—12; pl. 8,
fig. 6) in being more densely ribbed and in having a
whorl section as high as wide. These differences,
although small are nevertheless clear and easy to
identify. Consequently, the new subspecies of
Ch. choicensis is proposed.

Age. — Uppermost Lower Tithonian. V. men-
dozanus Zone.

Choicensisphinctes erinoides (BURCKHARDT, 1903)
Pl. 4, Figs. la—b; Text-Fig. 7).

1900a Perisphinctes aft. erinus D’ORBIGNY — BURCKHARDT.
p- 42, pl. 25, fig. 1.

1903 Perisphinctes erinoides BURCKHARDT, p. 51, pl. 8,
figs. 1-4.

1907 Perisphinctes erinoides BURCKHARDT — Haurr,
p- 197.

1931 Perisphinctes erinoides BURCKHARDT — WVEAVER,
p- 417.

1954 non Virgatosphinctes erinoides (BURCKHARDT) —
Inpans, p. 109, pl. 15, fig. 1 (= Psendinvoluticeras
douvillei).

Material. — One specimen. S.G.N. 8885/2;

relatively well preserved phragmocone with remains

of body chamber.

Description. — Large shell, inflated and
U/D ratio = 0.34. Umbilical
slope very high, almost vertical. Rounded umbilical
border. Flanks slightly convex, converging gradually
to a widely rounded periphery. The maximum width
occurs at the umbilical border. The ornamentation is
of low relief, and consists of primary ribs with
periumbilical swellings which disappear near the mid-
dle of the flank, giving way to bundles of 5 to 7
secondary ribs. They are equally spaced and of very
low relief, and cross the venter without interruption.
The suture line could not be detected.

somewhat evolute.

Measurements —

Specimen n° D U WD H W HN

S.G.N. 8885/22 120 41 034 47 51 0.92

“P.” erinoides

(Burck.,1903) 160 55 034 61 60 1.01
Remarks. — The specimen displays specific

characteristics in agreement with “P.” erinoides
BURCKHARDT (1903, p. 51, pl. 8, figs. 1—4). It differs
only in having somewhat less dense and sharper rib-
bing, possibly due to the greater weathering of the
BURCKHARDT’s specimen. In this latter specimen, the
higher whorl section is only present in an advanced
ontogenetic stage, while the younger volutions are
wider than high (Pl. 8, fig. 3, BurckHARDT, 1903). This
is also characteristic of the specimen described in this
study.

The enigmatic species erinoides of BURCKHARDT was
attributed by different authors to distinct genera such
as Aulacosphinctes (WEAVER, 1931, p. 417), Pararase-
nia ? (SparH, 1927—33, p. 469), Virgatosphinctes
(Inpans, 1954, p. 109) and Olcostephanus (BuRcK-
HARDT, 1930, p. 111, 112). In the opinion of the
writer, none of these generic attributions are accepta-
ble. In Pararasenia SpaTH, 1925 (type species: Aula-
costephanus zacatecanus BURCKHARDT, 1906, p. 67,
pl. 16, figs. 1—4), there is a tendency towards inter-
ruption of the ribs over the venter, resulting in the
presence of a smooth band. This feature is completely
absent in “P.” erinoides. With respect to Inpans’
classification, reasons were given above for the trans-
ferral of “Virgatosphinctes erinoides” to Pseudinvo-
luticeras douvillei. "The attributions of this species by
WEAVER to Aulacosphinctes,and by BuRCKHARDT firstly

to Perisphinctes and secondly to Olcostephanus, ap-
pear also to be inadequate, because of the considerable
morphological differences with regard to the diagno-
stic features of these genera.

“P.” erinoides appear to resemble the genus Choi-
censisphinctes more closely than any other. The simi-
larities of the internal whorl section and ornamenta-
tion of “P.” erinoides with Choicensisphinctes choi-
censis (BURCKHARDT, 1903, p. 50, pl. 6, figs. 10—12;
pl. 8, fig. 6) are very clear. A noticeable difference
between the two species is however, the suture line,
which is more elaborate in “P.” erinoides.

It is also possible that “P.” aff. erinus (D’Orb.)
BURCKHARDT (1903, p. 52, pl. 9, figs. 1—2; pl. 8, fig. 5)
belongs to Choicensisphinctes, although it shows a
smoother ornamentation, a somewhat more involute
shell and a more subtrapezoidal whorl section. P. aff.
erinus was formerly renamed by BuRCKHARDT himself
(1930, p. 110) as Craspedites limitis, but as can clearly
be seen, this attribution appears inadequate because of
the much different morphologic features of the Boreal
genus Craspedites.

Occurrence. — Lower part of the Vaca
Muerta Formation. Bed 2 of the Cerro Lotena sec-
tion (Virgatosphinctinae Beds), in association with
V. andesensis, V. mexicanus, V. burckhardti, V. den-
seplicatus rotundus, V. evolutus, P. douvillei, P. wind-
hauseni, P. (?) wilfridi, Ch. choicensis sutilis and Ch.
choicensis.

Age. — Uppermost Lower Tithonian. V. men-

dozanus Zone.

Genus AULACOSPHINCTOIDES SpATH, 1923

Type species. — Aulacosphinctes infundibu-
lus Unis, 1910, p. 371, pl. 72, figs. 1a—c.

Aulacosphinctoides aff. A. hundesianus (Unis, 1910)
Pl. 5, Figs. 1a—b; Text-Fig. 7n.

? 1910 Aulacosphinctoides hundesianus
pl. 71, figs. 3a-c; pl. 73, figs. 2a-c.

? 1923 Aulacosphinctoides hundesianus (UnLiG) — SPATH,
p- 299.

? 1960 Aulacosphinctoides hundesianus (Umris) — CoL-
LIGNON, pl. 151, figs. 605, 606.

Material. — One specimen. S.G.N. 8934/1:
phragmocone and body chamber, relatively well pre-
served.

Uni, p.374,

Description. — Medium size shell, discoidal
and rather evolute. U/D ratio = 0.47. Whorl
section subelliptical, somewhat depressed, wider than
high (see text-fig. 7n). Umbilical wall strongly in-
clined, umbilical border rounded with slightly convex

flanks, converging gradually to a widely rounded peri-
phery. The internal whorls are ornamented by nar-
row and elevate simple ribs, with mostly dicotomic
branching in the upper third of the flanks. In the
outer whorls, the ribs describe a sigmoidal curve, and
in the upper third of the flank they bifurcate or tri-
furcate, this being more common near the aperture.
In the last volution there are 52 primary ribs and 107
secondaries. There are also sharp constrictions
anteriorly bordered by a single rib which is more pro-
minent than the other ribs, and which also describes a
sigmoidal curve. The calcifized nature of the speci-
men prevented detection of the suture line.

Measurements —
Specimen n?° DU ZU/D7 Er WEEN

S.G.N. 8934/11 84 40 047 28 34 0.82

Remarks. — The specimen coincides exactly
with the genus Aulacosphinctoides SpaTH, 1923 (type
species: Aulacosphinctoides infundibulus Unis, 1910,
p- 371, pl. 72, figs. 1a, b). It also shows close affinities
with Torguatisphonctes SpaTH, 1924 (type species:
Ammonites torquatus J. C. de SOwERBY, 1840, pl. 61,
fig. 12). However, Aulacosphinctoides differs from
this latter genus in having more depressed whorls,
sigmoidal ribbing over the flanks, and frequent tripli-
cate branching in the body chamber.

Specifically, the specimen has closer affinities with
A. hundesianus (Unis, 1910, p. 374, pl. 71, figs.
3a—c; pl. 73, figs. 2a—c), included in Aulacosphinc-
toides by SparH (1923, p. 299), but the specimen from
Neuquen differs only in having somewhat narrower
ribs, and branching at a level rather higher on the

flanks.

A. chidamensis (Unuic, 1910, p. 376, pl. 74, figs.
1a—d) is also a closely related species, but differs in
its wider whorls and much more numerous trifurcate
ribs. A. brownei (MAarsHALL) SpATH (1923, p. 289,
pl. 17, figs. 1a—d), from the Tithonian of New Zea-
land, is very similar to A. bundesianus, differing only
in its less densely ribbed internal and external whorls.

With regard to the Argentine species, it should be
noted that “Aulacosphinctes” colubrinus \WEAVER
(non BURCKHARDT) (WEAVER, 1931, partim, p. 413,
pl. 44, fig. 301, non pl. 44, figs. 302, 303) probably
belongs to Aulacosphinctoides. “ Anlacosphinctes” cf.
bangei Inpans (non BURCKHARDT) (InDans, 1954,
p. 122, pl. 18, fig. 2), as suggested by ArkeLıL (1956,
p. 583), could also be included in SparH’s genus.

Occurrence. — Vaca Muerta Formation.
Bed 14 of the Cerro Lotena section, in association with
W. internispinosum.

Age. — Middle Tithonian.
Zone.

W. internispinosum

Aulacospbhinctoides sp. indet.

Material. — One specimen. S.G.N. 8927/1:
phragmocone poorly preserved, with internal whorls
just discernible and external whorls without test.

Description. — Shell discoidal, strongly evo-
lute. Whorl section not determinable because of
crushing of the specimen. Umbilical slope slightly
inclined, umbilical border rounded, and flanks gently
convex. In the internal whorls the ornamentation is
composed of elevated, narrow, irregularly spaced and
apparently bifurcate ribs. In the outer whorls, where
they can be observed, the ribs are mostly triplicate but
some are also biplicate. These ribs describe a gently
sigmoidal curve over the flanks. There are also con-
strictions anteriorly bordered by rather elevated ribs.

Remarks. — The morphological characteristics
of this ammonite in general resemble the genus Aula-
cosphinctoides. Althoguh quite similar to the hunde-
sianus-chidamensis group, the fragmentary preserva-
tion of the specimen does not permit a specific classifi-
cation.

Vaca Muerta Formation.
Bed 12 of the Cerro Lotena section, in association with
Subdichotomoceras araucanense n. sp.

Occurrence —

Age. — Middle Tithonian.
Zone.

W. internispinosum

Genus SUÜBDICHOTOMOCERAS SpaATH, 1925

Type species. — Subdichotomoceras lam-
plughi Spath, 1925 (= Perisphinctes lacertosus Pav-
Low (non FONTANNES), in: PAvLow & LAMPLUGH, 1892,
p- 110, fig. on text, p. 111).

Subdichotomoceras windhauseni (WEAVER, 1931)
Pl. 8, Figs. 2a—b; Text-Fig. 7m.

1931 Anlacosphinctes windhauseni WEAVER, p. 412, pl. 44,
fig. 300.

Material. — One specimen. S.G.N. 8940/2:
complete specimen with aperture, moderately pre-
served.

Description. — Medium size shell, strongly
evolute. Whorl section subcircular, as high as wide
(see text-fig. 7m). U/D ratio = 0.48. Ornamenta-
tion composed of narrow, prominent and rather wi-
dely spaced ribs. In the upper third of the flank, each
rib bifurcates into two branches which cross the venter
without interruption. Both primary and secondary
ribs have the same prominence. The aperture is
simple and is bordered by a single, much more elevated
rib which describes a sigmoidal curve.

Measurements —

Specimen n?° DZ UZEU/DT ZH WIEN

S.G.N. 8940/22 47 23 048 17 17 1.00

Remarks. — All morphological features of the
specimen agree with “Aulacosphinctes” windhauseni
WEAVER (1931, p. 412, pl. 44, fig. 300). Although
WEAVER did not figure the ventral view, he stated in
his very accurate description that the ribs cross the
venter without interruption. For this reason,
WEAVER’s attribution to the genus Aulacosphinctes
UhHuic can not be accepted. SpATH (1936, p. 26) and
ARKELL (1956, p. 582) have both suggested that
“A.” windhauseni could belong to the genus Pavlovia
ILovaısky, 1917 (type species: P. iatriensis var. prima-
ria ILovaısky, 1917, pl. 9, figs. 3a, b). This view has
also been accepted by the present author (H. LEANZA,
1973, p. 127, foot note). However, although the des-
cribed specimen strongly resembles Pavlovia, its attri-
bution to the genus Subdichotomoceras appears to be
more reasonable, because of the more widely spaced
ribs in the internal whorls. Indeed, this feature (cf.
ARKELL et al., 1957, p. L328) is the only one that can
be considered to differentiate the genera Pavlovia and
Subdichotomoceras. The densely ribbed internal
whorls of Pavlovia are well illustrated in the species
from the Kimmeridge Clay of Dorset figured by
NEAVvERSoN (1925) and Cope (1978) (see P. rotunda =
Pallasiceras rotundum (Sow.) NEAVERSson, 1925, p. 18,
pl. 1, fig. 6).

For the above reasons, the new combination Sub-
dichotomoceras windhauseni (WEAVER) is therefore
proposed. The specimen figured by WEAVvER is also
from Cerro Lotena, and has the same stratigraphic
position as the specimen described here. A species
formerly referred to as Pavlovia sp. indet., found in
Pichan Leufü and Mallin Quemado in Neuquen
(H. Leanza, 1973, p. 127), can also be definitely as-
signed to Subdichotomoceras (H. LEanza & C. Huco,
1977, p. 253).

These considerations indicate that the genus Sub-
dichotomoceras has an areal distribution in the
Andean-Madagascan-Himalayan domains during the
Lower and Middle Tithonian, while Pavlovia is
restricted to the Boreal realm in the Upper Kimmerid-
gian. It is for this reason that the origin of Pavlovia
from (via) Pectinatites, as suggested by Core (1978,
p. 527), appears to be more suitable than an origin
from Subdichotomoceras, as was formerly postulated
by Arkeıt et al. (1957, p. L332).

Occurrence. — Vaca Muerta Formation.
Bed 16 of the Cerro Lotena section, in association with
W. internispinosum, Corongoceras lotenoense and
Parapallasiceras aff. P. psendocolubrinoides.

37.

Age. — Uppermost Middle Tithonian. W. inter-
nispinosum Zone.

Subdichotomoceras araucanense n. sp.
Pl. 6, Figs. 1a—b, 3a—b; Text-Fig. 71.

Holotype. — S.arancanense H. LEANZA n. sp.,
figured in Pl. 6, figs. 3a—b. S.G.N. 8935/1.

Paratype. — S.araucanense H. LEANZA n. sp.,
figured in Pl. 6, figs. a—b. S.G.N. 8906/1.

Locus typicus. — Cerro Lotena, Neuquen
province, Argentina.

Stratum typicum. — Middle part of the
Vaca Muerta Formation in the Cerro Lotena area.

From Araucanos,
the name given to the Indians from Chile who lived in
the area of Neuqu£n, Rio Negro and Chubut.

Derivatio nominis —

Diagnosis. — Shell planulate, strongly evolu-
te. Whorl section subquadrangular with rounded
borders. Ribbing strong, sharp, regularly biplicate to
the aperture, and without interruption on the venter.
Aperture simple, somewhat projected, and without
lappets. Constrictions bordered by simple and strong
ribs.

Material. — S.G.N. 8935/1:
complete specimen, with phragmocone, body chamber
and aperture, very well preserved (Holotype).
S.G.N. 8906/1: phragmocone and damaged body
chamber (Paratype). S.G.N. 8935/2: phragmocone,
moderately preserved. S.G.N. 8935/3: incomplete
phragmocone, somewhat deteriorated. S.G.N. 8931/
9—13: five specimens, poorly preserved. S.G.N.
8942/8: complete specimen, rather well preserved.

10 specimens.

Description. — Shell planulate and strongly
evolute. U/D ratio = 0.48 to 0.51. Whorl section
subquadrangular, with rounded borders, as wide as
high (text-fig. 7 I) or slightly depressed. Umbilical
slope gently inclined, umbilical border rounded, and
flanks subplanate, gradually converging to a widely
rounded periphery. Ornamentation composed of
simple, elevated and narrow ribs, which are separated
by spaces equal to three times the rib width. In the
upper third of the flank each rib bifurcates into two
branches which cross the venter without interruption.

The pairs of secondary ribs are somewhat less sepa-
rated. In the last whorl of the holotype, there are
38 primary ribs and 72 secondaries. There are also
constrictions bordered by elevated, strong, and
somewhat projected single ribs. 'The suture line could
not be detected.

Measurements. — (better preserved speci-

mens only)

Specimen n?° D U UDT HZ WEN
S.G.N. 8935/1

(Holotype) 7303972 0.50582295.22521:.00
S.G.N. 8906/1

(Paratype) 627°3275,0.507 7167 7167°°1:00
S.G.N. 8935/j2 83 40 048 27 27 1.00
SIG.N: 28931/11784 243 710.517 32 7337 10:96

Remarks. — The morphological features of the
material described here, undoubtedly resemble those of
the genus Subdichotomoceras SpaTH (1925). Although
the material shows close affinities with species from
speeton (PavLow & LAMmPLUuGH, 1892), Cutch (SPATH,
1927—33) and Madagascar (CoLLiGnon, 1960), it does,
however, differ in some aspects from each of them.
Therefore a new species is proposed, named S$. arau-
canense.

This new species differs from $. lamplughi (PavLow,
in: Paviow & LAampLucH, 1892, p. 110, text-fig. on
p- 111, SD SraTtH, 1925, p. 120), which is the type spe-
cies of Subdichotomoceras, in having more elevated,
projected and denser ribbing.

Of the species from Cutch figured by SpatTH (1927
to 33, p. 521 to p. 526), close resemblances are shown
by S. inversum Spatun (1927—33, p. 521, pl. 84,
figs. 7a, b; pl. 85, fig. 4) and S. simplex SpATH (op. cit.,
p. 522, pl. 83, figs. 8a, b), but these differ in having a
lower density of ribs, with the bifurcation at a level
somewhat lower on the flanks.

S. n. sp. afl. $. inversum SpaTH of VERMA & WE-
STERMANN (1973, p. 183, pl. 30, figs. 1—2; pl. 31,
figs. 1—2, text-fig. 14B) from Mexico, has a much more
depressed whorl section. The Madagascan species
figured by CoLLicnon, v. gr. $S. mandarenense CoLLı-
GNoN (1960, pl. 149, figs. 597—599), differs in being
more involute and in having a more depressed whorl
section.

Finally, $S. windhauseni (WEAvER) differs from
S. arancanense n. sp. in having a lower density of ribs,
and a clearly greater angle of divergence of the secon-
dary ribs.

Occurrence. — Vaca Muerta Formation.
Bed 12 of the Cerro Lotena section, in association with
Aulacosphinctoides sp. indet.

Age. — Uppermost Middle Tithonian. W. inter-
nispinosum Zone.

Subdichotomoceras sp. juv. indet.
Pl. 8, Figs. 5a—b.

Material. — One specimen. $.G.N. 8942/2:
well preserved phragmocone of a young specimen.

Description. — Moderate size shell, relati-
vely evolute. U/D ratio = 0.39. Whorl section

suboval, somewhat depressed. Umbilical slope
strongly inclined, and the umbilical border, flanks and
periphery widely rounded. Ornamentation charac-
terized by elevated and acute ribs, with dichotomic
branching throughout the phragmocone. The outer
whorl as well as the body chamber is not preserved.
Bifurcation occurs in the upper third of the flank, and
the secondary ribs cross the venter without interrup-
tion. In the internal whorls, the ribs are not densely
spaced. Constrictions are present, bordered anteriorly
by a single rib.

Measurements —
Specimen n?° DU FU/DEE Er ENeENY

S:G.N., 78942/27462 18 210.397 715,5: 172. 0:88

Remarks. — The regular dichotomic branching
of the ribs throughout the shell, as well as its whorl
section, allow inclusion of this specimen in the genus
Subdichotomoceras. Because only the inner whorls
are preserved, with the evolution of the outer whorls
unknown, it is not possible to make a specific classifi-
cation. The specimen does, however, show some af-
finities with S. rebillyi CorziGnon (1960, pl. 148,
figs. 594—596) from the Lower Tithonian of Mada-
gascar. The latter species differs, however, in having
somewhat more depressed whorls.

Occurrence. — Vaca Muerta Formation.
Bed 7 of the Cerro Lotena section, in association with
A. proximus.

Age. — Middle Tithonian. A. proximus Zone.

Genus PARAPALLASICERAS SpartH, 1925

Type species. — Berriasella (Aulacosphinc-
tes ?) praecox SCHNEID, 1915, p. 64, pl. 3, fig. 5.

Parapallasiceras aff. P. pseudocolubrinoides
OrLorız, 1978
Pl. 8, Fig. 3; Text-Fig. 7p.

? 1978 Parapallasiceras psendocolubrinoides OLorız, p. 555,
pl. 55, fig. 3, text-fig. on p. 565.

Material. — Three specimens. $.G.N. 8947/1:
fragment of phragmocone with body chamber; one
side only preserved. S.G.N. 8935/5: complete speci-
men, but with the inner whorls not well preserved.
S.G.N. 8940/5: complete specimen not very well pre-
served.

Description. — Shell evolute, with wide and
shallow umbilicus. U/D ratio = 0.41 to 0.45.
Whorl section suboval, a little higher than wide (text-
fig. 7p). Umbilical border rounded and flanks
slightly convex, gradually converging to a rounded

periphery. Ornamentation composed of elevated,
acute, narrow ribs. The ribs normally biplicate or
triplicate at a level somewhat above the middle of the
flanks, and in a few cases also show poligyrate branch-
ing. They commence in the umbilical seam, and are
somewhat rursiradiate on the umbilical slope. On the
umbilical border they bend forward and cross the
flanks radially or a little prorsiradiately, without any
inflection. Over the venter the ribs, which display no
interruption, describe a small adoral projection. In
the inner whorls, however, they become weaker,
leading to the formation of a very gentle ventral
groove. In specimen S.G.N. 8935/5, there are numer-
ous examples of poligyrate branching. Lappets in the
aperture were not observed, but this is probably due
to the somewhat incomplete preservation of the body
chamber. Constrictions are present in the last whorl.
The suture line could not be detected.

Measurements. — (better preserved speci-
mens only)
Specimen n° DE 207 VD EIN EN
SGN 8947/10 650727., 10.417 220772 —
SIG!N. 8940/5587 725, .0:437 17? _
S{G-N 2 2.8955/520:7500 3430. 0.452021 207721.05
Remarks. — This material, in terms of general

shape, most strongly resembles the genus Parapallasi-
ceras SpatH, 1925. Although similar to Torguati-
sphinctes, its whorl section is more compressed; fur-
thermore, poligyrate branching is not present in the
latter genus. There are even more notable differences
with Berriasella, which is characterized by a more
involute shell, and a somewhat more compressed
whorl section and flattened venter, generally with a
persistent groove. In addition, branching of the ribs
in Berriasella occurs on a level rather lower on the

flanks.

Although Parapallasiceras was originally proposed
by SratH (1925, p. 133), but without an adequate
diagnosis, however, it has been recently redefined by
Zeıss (1968, p. 105). On the basis of this definition,
the described material can be readily included in Pa-
rapallasiceras.

MazEnoT (1939, p. 41) and DonzE & Enay (1961,
p. 185) considered that Berriasella praecox SCHNEID,
which is the type species of Parapallasiceras, could be
included in Berriasella, which they considered synony-
mus with the genus of SpaTH. On the other hand,
ARKELL et al. (1957, p. L329) and Zeıss (1968, p. 105)
stated that Parapallasiceras has sufficient distinctive
features to be considered an independent genus, an
opinion which is also accepted here.

Specifically, the closest affinities of the material are
with ?P. psendocolubrinoides Ororız (1978, p. 555,
pl. 55, fig. 3, text-fig. in p. 565), from the Lower

Tithonian of Southern Spain; this species differs only
Another
species which appears similar to the described material
is P. spurium (Schneip, 1915, p. 81, pl. 10, figs. 5, 5b;
pl. 11, figs. 5, 5a), from Neuburg, Germany. This
species, however, differs from the Cerro Lotena speci-
mens in having more projected ribbing in the inner
whorls and more involute shell.

in having somewhat less dense ribbing.

Occurrence. — Vaca Muerta Formation.
Bed 16 of the Cerro Lotena section, in association with
S. windhauseni, W. internispinosum and C. lotenoense.

Age. — Uppermost Middle Tithonian. W. inter-
nispinosum Zone.

Parapallasiceras aff. P. recticosta OLorız, 1978
Pl. 8, Figs. 6a—b; Text-Fig. 7g.

? 1978 Parapallasiceras recticosta OLorız, p. 553, pl. 55,
fig. 5, text-fig. on p. 565.

Material. — One specimen. S.G.N. 8942/5:

well preserved phragmocone, wigh remains of some-
what damaged body chamber.

Description. — Shell small, evolute, with
rather shallow umbilicus. U/D ratio = 0.35. Whorl
section suboval, a little higher than wide. Umbilical
slope strongly inclined. Umbilical border gently
rounded, passing upwards to short flanks which rapid-
ly converge to a rounded periphery (text-fig. 7q).
Ornamentation strong, with dichotomic branching
throughout the phragmocone. Ribs of the inner
whorls are fine, elevated and densely arranged. They
are somewhat projected and show dicotomic branch-
ing at a level a little above the middle of the flanks.
This type of ribbing is essentially the same in the last
whorl, but somewhat more widely spaced. The ribs
cross the venter with a slight adapertural convexity,
but without interruption. Pairs of secondary ribs are
less separated than contiguous pairs, a feature which
is clearer in the last part of the last whorl. The angle
of divergence of the secondaries is very small. No
tuberculation at the point of branching has been
observed. The illustration of the ventral view (pl. 8,
fig. 6b) represents the undamaged part of the last
whorl. In the figured specimen there are 36 primary
ribs and 69 secondaries, as well as two clear and deep
constrictions. The suture line was not detected.

Measurements. —
Specimen n° D U WD H W HNW

STCNE 3942/53 9 E47 2035561506
Note: The diameter of the umbilicus was meas-
ured on the unillustrated side, where the coiling is

more regularly preserved. The height and width of

the last whorl were measured immediately before the
deformed portion.

Remarks. — This relatively small, constricted,
Pavlovia-like specimen can tentatively be included in
the genus Parapallasiceras SpATH, 1925. Although at
first view it resembles Berriasella nitida SCHNEID (1915,
p- 70, pl. 5, figs. 4, 4b), it does not have simple ribs,
the ribbing is less flexuous, and the secondary ribs
show less divergence and cross the venter without
interruption. Although DonzE & Enar (1961, p. 188)
included this species in the genus Berriasella UnHLic,
1905, Ororız (1978, p. 608, 609) has recently stated
that it belongs to the genus Lemencia DonzE & EnaY
(1961). Another similarity, although perhaps only
superficial, is with the subgenus Epipallasiceras SPATH
(1936), and in particular with the variety superba
(SPATH, 1936, p. 57, pl. 39, figs. 2a, b) from the Glau-
conitic Series of Cape Leslie.

Specifically, the strong nature of the ribbing, the
entirely dicotomic branching of the ribs at a level
slightly above the middle of the flanks, and the fact
that these ribs cross the venter without interruption,
relate the specimen to ?. recticosta OLorız (1978,
p. 553, pl. 55, fig. 5, text-fig. on p. 565) from the Betic
ranges of Southern Spain. The latter species differs
from the Cerro Lotena specimen in its more compres-
sed whorls and its denser ribbing in the inner whorls.
As only one specimen exists, more detailed compari-
sions can not be made and it is therefore regarded as
Parapallasiceras aff. P. recticosta OLorız.

Occurrence. — WVaca Muerta Formation.
Bed 10 of the Cerro Lotena section, in association
with A. euomphalum.

A ge. — Uppermost Middle Tithonian. W. inter-
nispinosum Zone.
Parapallasiceras sp. indet.
Pl. 7, Figs. 2a—b; Text-Fig. 7 o.
Material. — Five specimens. S.G.N. 8942/4:

complete specimen, but with last part of body chamber
somewhat damaged. S.G.N. 8942/6—7: two in-
complete specimens, poorly preserved. S.G.N.
8942/10: small specimen, moderately preserved.
S.G.N. 8944/2: well preserved whorl fragment.

Description. — Shell strongly evolute, with
umbilicus very wide and shallow. U/D ratio =
0.45 to 0.49. Whorl section subcircular, as high as
wide. Umbilical slope strongly inclined, umbilical
border gently rounded, flanks somewhat convex and
the periphery slightly rounded (text-fig. 7 0). Orna-
mentation of inner whorls characterized by simple,
acute and elevated ribs, regularly disposed and with
bifurcation at a level somewhat below the line of

coiling. In the last whorls, ribbing remains essentially
the same up to the body chamber. The ribs commence
in the umbilical slope, where they are slightly rursira-
diate, but at the umbilical border they bend forward
and become clearly prorsiradiate. In the upper third
of the flanks the ribs bifurcate, crossing the venter
with a somewhat convex form, but without interrup-
tion. There are also some sharp constrictions bordered
anteriorly by a simple rib which occasionally inter-
rupts the regularity of the rest of the ribbing. The
suture line was not detected.

Measurements. — (better preserved speci-
mens only)
Specimen n?° D uU uD TEN:
S:G.N., 8942/47 75575272 0:49 2162 165521409
S:G.N.22,8942/ 102352164 LO AST DET ETR0D
Remarks. — This rather poorly preserved ma-

terial is included in the genus Parapallasiceras SPATH,
1925 (type species: Berriasella praecox SCHNEID, 1915,
p. 64, pl. 3, fig. 5) on the basis of its evolute shell,
whorl section and mainly biplicate ribbing from the
phragmocone to the body chamber. Although it also
strongly resembles Torguatisphinctes SparH, 1924
(type species: Ammonites torquatus J. C. de SOWERBY,
1840, p. 719, pl. 61, fig. 12), this latter genus has a
subquadrangular whorl section, and is more regularly
ribbed and lacks poligyrate branching. Although the
specimen described here shows some similarities with
T. regularis Zeıss (1968, p. 51, pl. 7, fig. 2) with regard
to its projected ribbing, the latter species shows a very
compressed whorl section (cf. Zeıss, 1968, text-fig. 5
on p. 61), a feature that appears to be completely aty-
pical of the true Torguatisphinctes from India (cf.
SPATH, 1927—33, p. 475 and following), which in
general has a subquadrangular whorl section. It is
therefore probable that the attribution of Zeıss could
be revised.

Considering the lack of better preserved material,
the specimens described here are regarded as Parapal-
lasiceras sp. indet.

Occurrence. — Vaca Muerta Formation.
Bed 18 of the Cerro Lotena section.

Age. — Uppermost Middle Tithonian. W. inter-
nispinosum Zone.

Genus PACHYSPHINCTES DieTrıcH, 1925

Typespecies. — P.africogermanus DIETRICH,
1925,.p. 12, pl. Ihe 2;Hpl.r 3,00g.01. SD Spar
1927—33.

Pachysphinctes americanensis n. sp.
Pl. 7, Figs. 1a—d; Text-Fig. 7k.

Holotype. — P. americanensis H. LEANZA
n. sp., figured in pl. 7, figs. la—d, text-fig. 7k. S.G.N.
8952/1.

Locus typicus. — Southern slope of Cerro
Lotena, province of Neuquen, Argentina.

Stratum typicum. — Upper part of the
Vaca Muerta Formation in the Cerro Lotena area.

Derivatio nominis. — From South Ame-
rica, continent were this species was found.

Diagnosis. — Very large shell, strongly evolu-
te. Whorl section depressed. Internal whorls have
regularly biplicate ribbing. Outer whorls display
strong, irregularly spaced ribs, with bi- or trichotomic
branching. Intercalatory ribs also present. In the
body chamber the ribing becomes simple, elevated and
distant.

Material. — Two specimens. S.G.N. 8952/1:
very well preserved phragmocone fragment with
remains of body chamber (Holotype). S.G.N. 8933/2:
phragmocone fragment with poorly preserved internal
whorls.

Description. — Very large, strongly evolute
shell. U/D ratio = 0.51. Umbilicus wide and rela-
tively deep. Internal whorls very depressed, with or-
namentation composed of simple, regularly spaced,
elevated and somewhat projected primary ribs that at
the coiling line bifurcate into two branches. No spines
occur at the point of bifurcation. In the last whorl,
and particularly in the body chamber, the shape of the
shell clearly changes. 'The whorl section is not as de-
pressed, the umbilical slope is more elevated and
strongly inclined, and the umbilical borders is more
gently rounded. With regard to the ornamentation,
the ribbing becomes stronger and more separated.
The ribs commence in the umbilical slope in the areas
where the test is preserved. They are initially rursi-
radiate, but then bend forward and over the middle
of the flank they are clearly projected, crossing the
periphery without interruption. In the first half of
the last volution the ribs bifurcate or trifurcate; also
present are simple ribs which disappear near the mid-
dle of the flanks. Towards the end of the last whorl,
the ribs are simple and become stronger and much
more widely spaced. The suture line is not preserved.

Measurements. — (better preserved speci-
mens only)
Specimen n° DEUTZ U/DT HT ENVZEEL NW.
S.G.N. 8952/1 196 101 051 58 69 0.84
Remarks. — The morphological features of the

described material resemble those of the genus Pachy-

sphinctes DIETRICH, 1925 (type species: P. africogerma-
nus DIETRICH, op. cit., p. 12, pl. 1, fig. 2; pl. 3, fig. 1),
which was later well illustrated by SpatH (1927—33).
Eleven species of this genus occur in the Middle Ka-
trol Beds of Cutch. In these beds, Pachysphinctes ıs
therefore the most common genus (cf. ARKELL, 1956,
p. 388). As noted by SprarH (1927—33, p. 469),
Pachysphinctes is an intermediate genus between Ka-
troliceras and Torguatisphinctes. In adopting the
name proposed by DIETRICH for this group, SPATH was
influenced not only by the illustration of the genotype,
but also by DierricH’s inclusion in this genus of
P. mülleri BuRcCKHARDT (1921, p. 33 = P. elizabethae
MÜLLER, 1900, p. 529, pl. 15, fig. 4).

The described material undoubtedly belongs to the
genus Pachysphinctes, and strongly resembles several
forms figured by SpaTH from Cutch. There is a close
resemblance, for example, with P. bathyplocus
(WAAGEN), reillustrated by SpatH (1927—33, p. 493,
pl. 77, figs. 1a—b; pl. 93, figs. 5, 9; pl. 94, fig. 4).
However, the specimens from Cerro Lotena differ
from the latter species in having more widely spaced
ribbing in the last whorl, especially in the body cham-
ber. P. crassus SparHu (1927—33, p. 492, pl. 85,
figs. 3a—b) is also a closely related species but differs
in having distinct periumbilical swellings, stronger
ribs, and a more depressed whorl section. According-
ly, it is proposed that the described material be desi-
gnated as a new species of Pachysphinctes, named
P. americanensis n. sp.

Occurrence. — Vaca Muerta Formation.
Bed 22 of the Cerro Lotena section, in association
with W. internispinosum.

Age. — Uppermost Middle Tithonian. W. inter-
nispinosum Zone.

Family ASPIDOCERATIDAE Zırter, 1895
Subfamily ASPIDOCERATINAE ZIırtteı, 1895
Genus ASPIDOCERAS ZIıTTEL, 1868

Type species. — Ammonites rogoznicensis
ZEUSCHNER, 1846, in ZıTTEL, 1868, p.117, pl. 24,
figs. 4—5.

Aspidoceras enomphalum STEUER, 1897
Pl. 8, Figs. 1a—b; Text-Fig. 10e.

1897 Aspidoceras euomphalum STEUER, p. 69, pl. 5, figs. 1-4
(= 1921, trans., pl. 5, figs. 1—4).

1907 Aspidoceras euomphalum STEUER — HAUPT, p. 191.

1926 Aspidoceras enomphalum STEUER — KRANTZ, p. 432.

1928 Aspidoceras euomphalum STEUER — KRANTZ, p. 12.

1931 Aspidoceras enomphalum STEUER — WEAVER, p. 436.

Material. — One specimen. S.G.N. 8931/15:
well preserved phragmocone with remains of body

chamber.

Description. — Medium size shell, inflated,
moderately involute, with deep umbilicus. Whorl
section suboval, depressed and wider than high. U/D
ratio = 0.30. Umbilical slope high and strongly in-
clined. Umbilical border rounded, with convex
flanks, converging strongly to a widely rounded peri-
phery. 'The maximum width occurs in the middle part
of the flanks. Ornamentation consists of two rows of
spines, of which the stronger and more prominent are
those situated in the middle of the flanks at the maxi-
mum width of the whorls. The other row, located at
the umbilical border, is characterized by smaller spines
which are only half as numerous as those situated in
the middle of the flanks. The remainder of the orna-
mentation consists of striae which are rursiradiate on
the umbilical slope and prorsiradiate over the rest of
the shell. On the umbilical slope these striae form
some folds which tend to disappear in the flank. The
suture line could not be detected.

Measurements. —
Specimen n° DAZU EU/DEL ESEWELENW.

S.G.N. 8931/15 32 25 030 40 50 0.80

Remarks. — The described specimen closely
resembles Aspidoceras euomphalum STEUER (1897,
p. 69, pl. 5, figs. 1—4), particularly with regard to the
internal whorls. It differs from A. andinum STEUER
(1897, p. 70, pl. 5, figs. 5—7) in being more involute
and in having a deeper umbilicus, more fine and large
spines, and more numerous spines in the interior row.
A. euomphaloides BuURCKHARDT (1906, p. 37, pl. 6,
figs. 5—8) is very similar to the described specimen
and, as was suggested by Krantz (1926, p. 432), could
be cospecific with it. On the other hand, A. guema-
dense BURCKHARDT (1906, p. 31, pl. 6, figs. 1—4) un-
doubtedly belongs to the species andinum of STEUER,
as was expressed by VERMA & WESTERMANN (1973,
p. 192). On the basis of illustrations, A. nenguensis
WEAVER (1931, p. 435, pl. 52, figs. 341, 342) could
also belong to A. euomphalum, but WEAVER (op. cit.)
has noted in his description that it has more elevated
whorls and a more elaborate suture line. A. longae-
unm Leanza (1945, p. 26, pl. 2, figs. 1,15), although
having a shell of somewhat similar shape, has stronger
and less dense spines.

Finally, it should be noted that A. euomphalum
STEUER (pl. 5, fig. 1) was incorrectly figured in the
Treatise of Invertebrate Paleontology (cf. ARKELL
et al., 1957, p. L346, fıg. 454, 3a—b) as “Spiticeras
(Kilianiceras) damesi” (STEUER, 1897).

Occurrence. — WVaca Muerta Formation.
Bed 10 of the Cerro Lotena section, in association with
P. aff. recticosta.

Age. — Upper Middle Tithonian. W. internispi-
nosum Zone

Fig. 10: Whorl sections of Berriasellidae and Aspidocera-
tidae. a: Hemispiticeras aff. H. steinmanni, S.G.N. 8950/1;
b: Aulacosphinctes proximus, S.G.N. 8944/1; c: Corongo-
ceras lotenoense, S.G.N. 8940/1; d: Windhauseniceras in-
ternispinosum, S.G.N. 8941/1; e: Aspidoceras euomphalum,
S.G.N. 8931/15. Natural size.

Family BERRIASELLIDAE SpaArTH, 1922
Subfamily HIMALAYITINAE SpartH, 1923
Genus WINDHAUSENICERAS A. F. LEanza, 1945

Type species. — Perisphinctes internispino-
sus KrANTz, 1926, p. 453, pl. 14, figs. 1, 2; pl. 15,
figs. 5, 6 (= 1928, transl., p. 39, pl. 2, figs. 3a, b and
4a, b).

Windhauseniceras internispinosum (KRANTz, 1926)
Pl. 8, Figs. 44—b; Pl. 9, Figs. la—b; Text-Fig. 10d.

Material. — This species is, next to P. zit-
teli, the most abundant in Cerro Lotena. The studied
collection contains twenty specimens, which are in
general well preserved. S.G.N. 8931/1—8: eight
moderately well preserved phragmocones. S.G.N.
8933/1: well preserved phragmocone with remains
of body chamber. S.G.N. 8934/1—2: very well
preserved phragmocone, with remains of body
chamber, somewhat distorted. S.G.N. 8935/4: whorl
fragments. S.G.N. 8940/3: complete specimen, with
internal whorls rather distorted. S.G.N. 8940/4:
very well preserved phragmocone (Pl. 8, figs. 4a—b).
S.G.N. 8941/1: phragmocone and body chamber, very
well preserved (Pl. 9, figs. 1a—b). S.G.N. 8942:1: very
distorted specimen. S.G.N. 8948/1: somewhat di-
storted phragmocone. S.G.N. 8949/1: somewhat
crushed but well preserved specimen. S.G.N. 8951/
1—2: poorly preserved specimens.

Description. — Shell discoidal, with greater
or lesser evolution depending upon whether it repre-
sents adult or young stages of growth. U/D ratio
ranges between 0.41 and 0.52. Young whorls are
wider than high, with very wide and rounded peri-
phery. Flanks strongly convex, gradually converging
to a gently inclined umbilical slope. Ornamentation
consists of strong, radial and prominent ribs. At the
lateroventral border they show a narrow and elevated
spine, enlarged radially. From this spine commence
two or sometimes three ribs of less prominence than
the primary rib; these cross the periphery without
interruption. The line of spines can be clearly
observed immediately below the line of coiling (see
pl. 8, figs. 4a—b).

Outer whorls are higher than wide, with suboval
whorl section. 'The periphery tends to become more
acute, and the umbilical slope more strongly inclined.
Ornamentation is characterized by rectiradiate or
somewhat prorsiradiate, simple or biplicate ribs. The
bifurcation takes place in the middle part of the
flanks; spines or tubercules are absent. The resulting
secondary ribs retain the same prominence as the pri-
maries, crossing the periphery transversally without
interruption. Simple ribs extending from the peri-
phery to different levels on the flanks are also present.
The aperture is simple, describing only a somewhat
sigmoidal curve.

The calcitized nature of the specimens prevented
detection of the suture line.

Measurements. — (better preserved speci-
mens only)
Specimen n° DE AU U/DE EZ WEHEN
S1G.N2228950/.10 2938°.475220:500°295 2271.07
S:G.N7 8951/10717 3720055222277 237 70,95
S:G.N. 223933110 2972 5102.0527 7297237 71103
S.G.N. 8934/22 108 47 043 36 35 1.02
S.G.N. 8940/37 70° 327 10.45. 247.25 70.96
SEN 394112937 2427710452 307°? _
S.G.N. 8948/11 152 74 048 54 52 1.03
S.G.N. 8949/1 140 58 041 58 56 1.03

Remarks. — The described material is identical

to the genus Windhauseniceras Leanza (1945), and
coincides specifically with its type species, that is,
Perisphinctes internispinosus Krantz (1926, p. 453,
pl. 14, figs. 1, 2; pl. 15, figs. 5, 6 = 1928, transl. p. 39,
pl. 2, figs. 3a, band 4a, b). The type species was also
found in the Cerro Lotena area (cf. KrAnTz, 1926,
p. 454).

W. internispinosum is very variable depending on
its ontogenetic stage, particularly with regard to the
ornamentation of the body chamber. It is, in fact,
very difficult to find identical specimens. On the
other hand, the diagnostic features of the genus always
remain the same. Therefore, it was not considered
advisory to propose new varieties for the described
material. It should be noted, however, that virgato-
tomic branching has not been observed, as it has in
W. hbumphreyi Leanza (1949, p. 240, pl. 1, figs. 1, 1a,
2, 2a) from the Tithonian of Arroyo Los Molles,
Neuquen, Argentina.

Occurrence. — WVaca Muerta Formation.
Beds 9, 14, 16 and 22 of the Cerro Lotena section.

Age. — Uppermost Middle Tithonian. W. inter-
nispinosum Zone.

Genus HEMISPITICERAS SPpaATH, 1925

Type species. — Reineckeia steinmanni

STEUER, 1897, p. 28, pl. 8, figs. 1—4.

Hemispiticeras aff. H. steinmanni (STEUER, 1897)
Pl. 9, Figs. 2a—b; Text-Fig. 10a.

? 1897 Reineckeia steinmanni STEUER, p. 28, pl. 8, figs. 1-4.

? 1921 Reineckeia steinmanni STEUER, pl. 8, figs. 1-4.

? 1925 Hemispiticeras steinmanni (STEUER) —
p. 144 (Gen. nov.).

Material. — One specimen. S.G.N. 8950/1:
well preserved phragmocone.

SPATH,

Description. — Discoidal shell, strongly evo-
lute. U/D ratio = 0.49. Inner whorls coronate,
similar to those of Windhauseniceras or Stephanoce-

ras. Outer whorl section is, by contrast, slightly
higher than wide. Umbilical slope gently inclined,
umbilical border rounded, but in the inner whorls
slightly flattened. Ornamentation characterized by
strong, elevated and acute ribs that divide at the line
of coiling into two or three branches which are less
prominent and wider than the primaries. At the point
of furcation are radially elongate tubercules, some-
times poorly preserved. This type of ribbing remains
the same in the inner and outer whorls, in contrast to
the genus Windhauseniceras. In the last whorl there
are 35 primary ribs and 76 secondaries, which cross
the venter without interruption, and display a some-
what adapertural convexity. Calcitization prevented
detection of the suture line.

Measurements. — (inmm)
Specimen n?° Di EURE DEE EN E ENT:

S.G.N. 8950/11 140 69 049 37 46 0.80

Remarks. — The general shape of the shell of
this specimen closely resembles that of the genus He-
mispiticeras SPATH, 1925 (type species: Reineckeia
steinmanni STEUER, 1897, p. 28, pl. 8, figs. 1—4), dif-
fering only in having smaller and rounded tubercules
at the point of the rib furcation. Therefore, the spe-
cimen is considered here as H. aff. H. steinmanni
(STEUER).

Although the inner whorls ornamentation is almost
identical to that of Windhauseniceras LEanza, 1945
(type species: P. internispinosus KrANTz, 1926, p. 453,
pl. 14, figs. 1, 2; pl. 15, figs. 5, 6 = 1928, transl., p. 39,
pl. 2, figs. 3a, band 4a, b). However, in the described
material this ornamentation continues in the outer
whorls, while in the LEAnza’s genus the ribbing loses
tubercules, closes together and reverts to a typical
Perisphinctes style.

Another genus which shows affinities with the des-
cribed specimen is Paskentites Imlay & Jones, 1970
(type species: P. paskentaensis Imlav & Jones, 1970,
p- B47, pl. 13, figs. 11—17), from the Middle Valan-
ginian of the Buchia pacifica Zone, in northwestern
California and southern Gregon, U.S.A. This genus
“...is represented by eight specimens of which most
are fragmentary and crushed laterally” (Imray &
JoNnEs, op. cit., p. B47). Judging from the illustra-
tions, the apparent projection of the ribs — which
forms chevrons over the venter — is essentially the
only difference from the species described here.

Occurrence. — WVaca Muerta Formation.
Bed 20 of the Cerro Lotena section.
Age. — Uppermost Middle Tithonian. W. inter-

nispinosum Zone.

Genus AULACOSPHINCTES Uarıc, 1910

Type species. — Ammonites mörickeanus
OrreL, 1863, p. 281, pl. 80, figs. 2a, b. SD SrartH,
1924, p. 16.

Aulacosphinctes proximus (STEUER, 1897)
Pl. 6, Figs. 2a—b, 4a—b and 5a—b; Text-Fig. 10b.

1897 Reineckeia proxima STEUER, p. 34, pl. 8, figs. 7-11.
(= 1921, transl., pl. 8, figs. 7-11).
1907 Perisphinctes proximus (STEUER) — HauPT, p. 192.
? 1931 Aulacosphinctes proximus (STEUER) — WVEAVER,
p- 411, pl. 44, figs. 298 and 299.

Material. — Ten specimens which are parti-
cularly suitable for the study of this genus, are present
in the collection. S.G.N. 8922/1: very well preserved
phragmocone of young specimen (pl. 6, figs. 4a—b).
S.G.N. 8922/2: phragmocone with remains of body
chamber. S.G.N. 8944/1: very well preserved phrag-
mocone with remains of body chamber (pl. 6,
figs. 2a—b). S.G.N. 8937/1—6: six small specimens,
mostly fragmentary and not very well preserved.
G.P.1.T. 1545/3: internal mold of phragmocone and
body chamber, very well preserved (pl. 6, figs. 5a—b).

Description. — Shell of moderate size, pla-
nulate, and strongly evolute.e. U/D ratio ranges
between 0.46 and 0.50. Umbilicus very wide and
shallow. Internal whorl section subtrapezoidal,
higher than wide. Outer whorl sections somewhat
depressed and of subcircular shape (text-fig. 10b).
Umsbilical slope gently inclined, umbilical border
rounded, flanks gently convex and the periphery
somewhat flattened. Ornamentation characterized by
simple, sharp, acute and fine ribs. They commence in
the umbilical seam, cross the umbilical slope in a
somewhat rursiradiate manner, bend forward at the
umbilical border, and cross the flanks in a recti- or
prorsiradiate fashion. Just above the middle of the
flanks, most of the ribs bifurcate into two branches of
the same shape as the primaries. The more anteriorly
situated are prorsiradiate, while those located poste-
riorly are somewhat rursiradiate. All the ribs are
interrupted over the venter, where a shallow groove is
developed, which is more pronounced in the inner
whorls. Interruption of the ribbing also occurs in the
body chamber, although not as clearly (see Pl. 6,
Fig. 5b). The number of ribs increases with age. For
example, for a diameter of 40 mm there are about
30 primaries, while for one of 60 mm there are about
40. The suture line, observed in the septa limiting
with the body chamber, is very simple, displaying an
E lobe slightly larger than L, but of the same width.
The L/U saddle is two thirds the size of theL lobe.

Measurements. — (better preserved speci-
mens only)
Specimen n° DIE US U/DESEII NZ EV
SIGINE 18922/2617 °3177.0597 172137 994
S.G.N. 8944/11 60 30 050 17 18 094
SIE.NE EB I22 1 43072710487 7137137 1.09
SIG. 8937110367170 094721272 19273100
S.@IN2 893716% 3307147 70,46) 1177197 140
G-PAHT. 1545/37587 729770507 1871977094

Remarks. — The morphological features of the

described specimens closely resemble those of the genus
Aulacosphinctes UHLig, 1910 (type species: Ammonites
mörickeanus OrrEL, 1863, p. 281, pl. 80, figs. 2a, b).
Although Untic stated with regard to the ventral
groove that... “As is well known, its development
is restricted to the chambered nucleus, and does not
extend to the body chamber” (UnHric, 1910, p. 345),
in the Cerro Lotena species the ventral groove is ap-
parently also present in the body chamber.

Specifically, the material closely agrees with “Rei-
neckeia” proxima STEUER (1897, p. 34, pl. 8, figs. 7 to
11) which was transferred in 1910 to the genus Aula-
cosphinctes by UnHriG himself (op. cit., p. 347). Alt-
hough at first view the material also resembles Aula-
cosphinctes colubrinoides (BURCKHARDT, 1903, p. 57,
pl. 10, figs. 9—11), this similarity appears superficial
because in this latter species, as indicated by
BURCKHARDT’s description (op. cit., p. 57), the ribs
cross the venter without interruption, a feature which
is considered diagnostic to the identification of this
genus. It is worth noting that A. colubrinoides was
transferred by SpatH (1925, p. 145) to the genus
“Crendonites” BuckMAn (1923) (= Glaucolithites
Buck., 1922), although the same author later stated
that it... “probably does not belong to this genus,
contrary to my previous view” (SPATH, 1936, p. 31).
With regard to A. mörickeanus (Oper), the described
species differs in having somewhat rounded flanks,
wider whorls, more rapid range of growth, and ab-
sence of ribs with tricotomic branching (cf. UHLic,
1910, p. 351). Another species rather similar to
A. proximus is A. parvulus Unis (1910, p. 364, pl. 32,
figs. 4a—d) from the Spiti Shales; however, this latter
species has a deeper ventral groove and simpler rib-
bing. With regard to the Madagascan forms, the ma-
terial described here resembles A. proximus (STEUER)
var. angusta CoLLIGNoN (1960, pl. 172, fig. 731). The
A. proximus figured by Weaver (1931, p. 411,
pl. 44, figs. 298, 299) does not display the interruption
of the ribs over the venter and therefore its attrıbu-
tion to Aulacosphinctes is doubtful. Finally, it can
noted that A. occultefurcatus (WAAGEN, 1875, p. 195,
pl. 1, figs. 4a, b) from Cutch, India, and A. wanneri
KranTtz (1928, p. 42, pl. 2, figs. 6&a—b) from Arroyo
de la Manga, Mendoza, Argentina, are also closely
related species.

Occurrence. — Vaca Muerta Formation.
Bed 7 of the Cerro Lotena section, in association with
Subdichotomoceras sp. juv indet. and Laevaptychus
crassissimus.

Age. — Middle part of the Middle Tithonian.

A. proximus Zone.

Genus CORONGOCERAS SPATH, 1925

Type species. — Corongoceras lotenoense
SPATH, 1925, p. 144 (= “Hoplites köllickeri” Haupr,
1907 (non Orper), p. 201, pl. 9, figs. 7a—e).

Corongoceras lotenoense SPATH, 1925
Pl. 6, Figs. 6ca—b; Text-Fig. 10c.

1907 Hoplites köllickeri Haupt (non OPrer), p. 201,
pl. 9, figs. 7a-e.

1925 Corongoceras lotenoense SPATH, p. 144 (Gen. nov.,
type species).

1926 Berriasella (Corongoceras) lotenoensis SPATH —
KRrANTZ, p. 444 (= 1928, transl., p. 28).

1931 Berriasella cf. koellickeri (OPprEL) STEUER— WEAVER,
p. 444.

? 1969 Corongoceras cf. lotenoense SparH — HELMSTAEDT,

p- 78.

Material. — Two specimens. S.G.N. 8932/1:
whorl fragment with remains of body chamber, very
well preserved. S.G.N. 8940/1: phragmocone and
body chamber, moderately preserved (pl. 6, figs. ca—b).

Description. — Discoidal shell of medium
size, strongly evolute. U/D ratio = 0.50. Umbilical
slope gently inclined, with slightly convex flanks and
somewhat flat venter (as in Berriasella). Whorl sec-
tion as high as wide (text-fig. 10c). Ornamentation
strong, formed by very acute ribs. All ribs bifurcate
on the middle of the flanks. At the point of branch-
ing an acute tubercule, rather radially elongate, is
developed. At the lateroventral border, all secondary
ribs show a new row of tubercules elongated trans-
versely to the shell venter; they tend to disappear in
the siphuncle. In the last whorl are 24 primary ribs
and 40 secondaries. The suture line was not detected.

Measurements. — (better preserved speci-
men only)

Specimen n° DESUZEUDZSHT ENG EU

S.G.N. 8940/11 54 27 050 18 18 1.00

Remarks. — The whorl section, evolution,
number of ribs and general shape of the ornamenta-
tion are identical to Hoplites köllickeri Haupr (non
Orrer) (1907, p. 201. pl. 9, figs. 7a—e), also from
Cerro Lotena. This species was proposed by SPATH

(1925, p. 144) as the type species of Corongoceras lo-

tenoense. Therefore, the described material is attri-
buted to this species. “Reineckeia koellickeri” STEUER
(non OprEL, non HaurT) (1897, p. 31, pl. 8, figs. 5, 6),
which was found by BoDENBENDER (1892) in Loncoche
creek, Mendoza, Argentina, undoubtedly belongs to
the genus Corongoceras, but differs from the type
species in having a more disordered ribbing as well as
a larger umbilical diameter. WEAVER (1931, p. 444),
stated that Berriasella cf. koellickeri (OprEL) STEUER
“...occurs in the lower part of the Upper Tithonian
strata at Cerro Loteno...”, that is, in a similar stra-
tigraphic position to the described material. WEAVER
did not illustrate this species, but in view of his des-
cription and the fact that it appears in the same stra-
tigraphic position, it can be included in Corongoceras
lotenoense. The specimens referred to by KrANTZz as
Berriasella (Corongoceras) lotenoensis (KRANTz, 1926,
p. 444 = 1928, p. 28) are also from Cerro Lotena.

Recently, another record of Corongoceras, which

probably belongs to the lotenoense species of SPaTH,
was cited from Nepal (HELMSTAEDT, 1969, p. 78).

Corongoceras loetonense (sic) var. fortior COLLIGNON
(1960, pl. 167, fig. 637), judging by the illustrations,
does not appear to belong to the species of SpATH, as it
displays greater involution and less divergent sec-
ondary ribs. The species referred to as C. cordobai
by VERMA & WESTERMANN (1973, p. 248, pl. 52, figs. 4,
5; pl. 54, fig. 1, text-fig. 28 B) should not be assigned
to Corongoceras because of the lack of bifurcation of
the ribs, a feature which is considered diagnostic to the
identification of this genus.

Vaca Muerta Formation.
Bed 16 of the Cerro Lotena section, in association
with S. windhauseni, W. internispinosum and P. aff.
P. psendocolubrinoides.

Occurence —

Age. — Uppermost Middle Tithonian.
nispinosum Zone.

W. inter-

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| Zieeinn | 5 | 51-2 München, 25. April 1980 ISSN 0373 - 9627

Rhaeto-Liassic Mammals from Switzerland and
West Germany

WILLIAM A. CLEMENS*)

With 5 text figures and plates 10—12

ABSTRACT

European mammals and advanced mammal-like
reptiles of Rhaeto-Liassic (Late Triassic-Early Juras-
sic) age are now known from localities in Switzerland,
West Germany (BRD), France, and Great Britain.
The Rhaetic bonebeds at Hallau, Switzerland, and in
Baden-Württemberg, southwestern West Germany,
contain samples of the animals that lived on the deltas
and other coastal regions along the northwestern flank
of the Vindelizian High, a continental area covering
parts of northern Switzerland and southern West Ger-
many. During the Rhaetian and early Liassic large
parts of northwestern Europe were inundated by
marine transgressions from the west and south creating
an ephemeral archipelago that was largely submerged
later in the Jurassic. Differences in known represen-
tation of mammals in Rhaeto-Liassic local faunas of
northwestern Europe probably reflect: 1) small sample
sizes of some local faunas, 2) differences in age within
the Rhaeto-Liassic interval, and 3) the evolutionary
diversification of insular faunas.

Rhaetic bonebed local faunas of Hallau and Baden-
Württemberg are known to include haramiyids, verte-
brates of uncertain but probably mammalian affinities.
Morganucodon (Mammalia, Triconodonta) is repre-
sented at Hallau by a new species. Two other new
mammalian species in the Hallau local fauna are
referable to new genera. One is provisionally allo-
cated to the Morganucodontidae; the other is not
referable to any previously known family or order.
Tricuspes (?Mammalia) is recorded from Rhaetic
bonebeds at Hallau and in Baden-Württemberg.
Tritylodontids (Reptilia, Synapsida), present in sever-
al Rhaetic bonebed local faunas of Baden-Württem-
berg, are not part of the Hallau local fauna.

The taxonomic diversity of mammals now known
from a very few samples of Rhaetian and Liassic age
strongly suggests the time of origin of the Mammalia
was significantly earlier in the Triassic.

KURZFASSUNG

Europäische Säugetiere und fortschrittliche säuge-
tierähnliche Reptilien des Räto-Lias (Obertrias — Un-
terjura) sind jetzt von Lokalitäten in der Schweiz,
Westdeutschland (BRD), Frankreich und Großbritan-
nien bekannt. Die Rät-Bonebeds von Hallau (Schweiz)
und Baden-Württemberg (Südwest-Deutschland) ent-
halten Reste von Wirbeltieren, die in Delta- oder an-
deren Küstengebieten entlang der Nordwest-Flanke
des Vindelizischen Landes, eines kontinentalen Gebie-
tes im Bereich der heutigen Nordschweiz und des süd-
lichen Westdeutschland lebten. Während des Rät und
tieferen Lias waren weite Teile von Nordwesteuropa
durch marine Transgressionen von Westen und Süden
überflutet. Sie schufen einen vorübergehenden Archipel,
der im höheren Jura weitgehend wieder versank. Un-
terschiede innerhalb der bisher bekannten Vorkommen

von Säugetieren in den rätoliassischen Lokalfaunen
von Nordwest-Europa spiegeln wahrscheinlich wider:
1. kleine Probengröße einiger Lokalfaunen, 2. Alters-
unterschiede innerhalb der Zeitspanne des Rätolias
und 3. eine stammesgeschichtliche Differenzierung in
Inselfaunen.

Lokalfaunen aus den Rät-Bonebeds von Hallau und
Baden-Württemberg enthielten nach bisheriger Kennt-
nis Haramiyiden und Wirbeltiere von unsicherer, aber
wahrscheinlicher Säugetierzugehörigkeit. Morganuco-
don (Mammalia, Triconodonta) ist in Hallau durch
eine neue Art vertreten. Zwei weitere neue Säugetier-
arten werden auf neue Gattungen bezogen. Eine wird

*) Prof. Dr. W. A. Cemens, Dept. of Paleontology and
Museum of Paleontology, University of California Berkeley,
Berkeley, Calif. 94720, U.S.A.

vorläufig zu den Morganucondontidae gestellt; die an-
dere ist mit keiner anderen bisher bekannten Familie
oder Ordnung vergleichbar. Tricxspes (?Mammalia)
wird aus den Rät-Bonebeds von Hallau und Baden-
Württemberg nachgewiesen. Tritylodontiden (Repti-
lia, Synapsida), die in einigen Lokalfaunen der Rät-

Bonebeds Baden-Württembergs vorkommen, fehlen in
Hallau. Die taxonomische Vielfalt von Säugetieren,
die bis jetzt von sehr wenigen Proben des Rät und Lias
bekannt sind, spricht sehr dafür, daß die Entstehungs-
zeit der Säugetiere auf jeden Fall in einen deutlich
früheren Abschnitt der Trias fällt.

TABLE OF CONTENTS

Abstract 51
Kurzfassung 51
Introduction & 53
Designation of specimens 53
Abbreviations 53
Acknowledgements R 54
Geology and Paleogeography . ; N: 54
Rhaetic local faunas of the Tabingen. Stuttgart a aTEa N, We er TE ARE 56
Hallau local fauna . r : 59
Saint-Nicolas-du-Port local Fauna, France x ra 2362
Late Triassic-Early Jurassic local faunas from ge Ale western Ger Bram = sr 163
Paleogeography . are A
Fossils from the Tübingen- Stuttgart: area, Baden- „Württemberg, West ernany, ABA AR6E
Introduction . 66
Systematics 66
Class enmaliz : 66
Order and Family incertae ei s 66
Tricuspes . : 66
Tricuspes Bubınzenee } 66

Family Haramiyidae 68
Thomasia 68
Thomasia antigua 68

? Thomasia sp. 8 IP ROSE 2 PAR IIR. VEREIN INNEEN DENN ERBE O

Hallau local fauna, Kanton Schaffhausen, Seitzerland a A: DA ET U EN ©
Systematics Ö 70
Class Reptilia . 70
Order Pterosauria 70
Order Therapsida . 70
Family Triylodontidae 70

Class ?Mammalia ; 71
Order and Family incertae see 71
Tricuspes 71
Tricuspes cf. linkensien 71

Family Haramiyidae 71
Thomasia : 71

cf. Thomasia antigua i 71

Thomasia anglica 72

?Thomasia sp. 72

cf. Thomasia sp. 72

Haramiya : 73
Haramiya moorei . 73
Haramiyid ?gen. et sp. . 74

Class Mammalia £ 75
Order Triconodonta 75
Family Mörsanueodontidae 75
Morganucodon . 75
Morganucodon peyeri se nov. 75

? Morganucodon sp. 80

Order ?Triconodonta 3 81
Family ?Morganucodontidae . 81
Helvetiodon gen. nov. P s1
Helvetiodor schutzi sp. nov. 81

Order and Family incertae sedis 85
Hallautherium gen. nov. : 85
Hallautherium schalchi sp. nov. 85
Systematic relationships 87

Literature cited .

INTRODUCTION

Mesozoic mammals were for the most part minute
creatures in comparison to the dinosaurs and their
other reptilian contemporaries. Even under the best
of conditions their tiny bones and teeth are rarely seen
as they weather out of the entombing sediments.
About the middle of the 19th Century two vertebrate
paleontologists, Prof. T. Plieninger of Stuttgart and
Charles Moore of Bath, undertook research on natural
concentrations of fragmentary small bones thought to
be of Late Triassicage. Each of them washed the fos-
siliferous sediments in screens to remove as much of the
associated sand and mud as possible. This separated
the fossils and produced an even richer concentrate for
sorting. Thus the screen washing technique of collec-
ting fossil vertebrates got its start.

With rare exceptions, in the following years of the
19th and early 20th centuries collectors focused their
attention on the mighty and gigantic vertebrates of
the past. Remains of smaller, mouse-sized animals
were found, but frequently these were almost acciden-
tal by-products of the search for larger animals.
Almost a century later Profs. W. Kühne, C. W. Hıs-
BARD, and a few others championed the inclusion of
screen washing in the basic repertoire of collecting
techniques. Modern modifications of these techniques
and improvement of equipment now permit recovery
of minute fossils even when they occur in very low
densities in the sediments.

After Plieninger’s work many years elapsed before
additional specimens of mammals and advanced mam-
mal-like reptiles were recovered from the Rhaetic
bonebeds of Baden-Württemberg. The next collec-
ting programs were those carried out by E. von HuENE
and, later, Prof. ©. H. ScHınpEewoLFr. The entire col-
lection of mammalian fossils from Hallau was obtain-
ed by Prof. B. PEyer who devoted many years to the
processing of screen washing concentrates obtained
from rock collected in 1942.

In 1956 Prof. PEyEr published a monograph on
mammals and reptiles from the Rhaetic bonebed at
Hallau. This was an interim report based on the col-
lection available in 1951. Sorting of the screen
washing concentrates from Hallau was continued and,
ultimately, almost doubled the size of the sample.

My involvement in research on the mammals from
Hallau began in 1961. A postdoctoral fellowship
from the National Science Foundation made it pos-
sible for me to visit Zürich where Prof. PEYER intro-
duced me to his work. Unfortunately Prof. PEYER
died in 1963 before he could complete his projected
study. In 1974-75, thanks to a fellowship from the
JoHn Sımon GUGGENHEIM MEMORIAL FOUNDATION,
I was able to return to Europe. Prof. E. KuHn-ScHnY-
DER graciously made the collections from Hallau avail-
able for my study. Also it was possible to review the

pertinent collections of Rhaeticmammalsand advanced
mammal-like reptiles from sites in adjacent parts of
Baden-Württemberg. These, like the collections from
Hallau, had yet to be analyzed in light of the flood of
new data coming from research on the Rhaeto-Liassic
local faunas of southern Wales. An award from the
ALEXANDER-VON-HUMBOLDT-STIFTUNG, the hospitality
of the Institut für Paläontologie und historische Geo-
logie, Universität München, and a leave of absence
from the University of California Berkeley made it
possible for me to return to Europe in 1978-79 and
provided the freedom and support necessary to finish
my research.

Designationofspecimens

The fossils considered here are elements of several
different collections and, over the years of the past
century, some have been left without specific museum
catalogue designations; others have been given several
different catalogue numbers. The following are
utilized in this paper:

Fossils in the Charles Moore collection, Bath
Geology Museum, Bath, England, are identified by a
three digit number with the letter Cor Masa prefix.

Elements of the collections of the Institut und Mu-
seum für Geologie und Paläontologie, Universität Tü-
bingen, have the prefix G.1. T.

In his monograph PEveEr (1956) identified fossils
from Hallau in the collections of the Paläontologi-
sches Institut und Museum der Universität Zürich with
Roman numerals. The same numerical designations,
although written in arabic numerals, were used to
identify the figures in the plates of his monograph.
Fossils collected after the completion of the mono-
graph were numbered separately and sequentially
with arabic numerals. These designations are record-
ed here as NC (= new collection) 1, 2, etc. Subse-
quently the entire collection was recurated and the
fossils given sequential numbers, in arabic numerals,
with the prefix AIII.

In the descriptions of the fossils from Hallau these
catalogue data are summarized at least in the lists of
referred material. In parentheses after the current
catalogue number the reader will find either PEvEr’s
designation of the specimen in Roman numerals fol-
lowed by a reference to the Tafel in his monograph
(PEYER, 1956) on which it is illustrated, or its NC
number in the new, hitherto unpublished collection.

Abbreviations
The following abbreviations have been used:

CV = coefficient of variation

M = mean

N = number

OR = observed range of variation
S = standard deviation

Acknowledgements

My involvement in studies of European Mesozoic
mammals began in the academic year 1960-61 when,
supported by a National Science Foundation postdoc-
toral fellowship, I was able to work with Dr. Kenneth
KERMACK at University College London. In following
years I have been fortunate in being able to return to
Europe and continue my research and education.
Many colleagues and institutions have contributed to
this and to all those named here and many others I am
deeply grateful.

This paper is focused on the collections of mamma-
lian fossils from northern Switzerland and Baden-
Württemberg. For permission to study the collection
from Hallau, information and advice, and provision
of excellent research facilities during my visits, I wish
to thank Prof. Drs. B. PEYEr, E. KUHN-SCHNYDER,
and H. Rızser, and Dr. K. A. HÜnERMANN of the
Paläontologisches Institut und Museum der Universi-
tät Zürich. Dr. R. SCHLATTER, Museum zur Allerheili-
gen, provided considerable information concerning the
geological setting of the Hallau bonebed.

At the Institut und Museum für Geologie und Pa-
läontologie, Universität Tübingen, Drs. F. WESTPHAL
and W.-E. Reır assisted me in my review of the col-
lections. Dr. C. HEMLEBEN arranged for preparation
of scanning electron microscope pictures of several
fossils. Dr. R. WırD, Staatliches Museum für Natur-
kunde, Stuttgart, helped me in both recapitulating the
history of the type of Thomasia antigqua and exploring
the possibility that some of the minute teeth found in
Rhaetic bonebeds might be from the dentitions of
pterosaurs. Also, my sincere thanks go to Dr. DEnISE
SIGOGNEAU-RussELL, Institut de Paleontologie, Paris
for discussions and the opportunity to review her
recent discoveries at Saint-Nicolas-du-Port.

Many British colleagues have helped me, in particu-
lar I would acknowledge Drs. K. A. and D. M. Ker-
MACK, Frances MussETT, and Patricia M.Lees not only
for the opportunity to study material in the collec-
tions of University College London, but also for the
many days spent with them at fossil localities in
southern Wales and southwestern Britain. Ders.
R. PArrınGToN and K. JoYsey gave me access to col-
lections in the Zoology Museum, Cambridge Univer-
sity. Prof. P. M. ButLer, Royal Holloway College —
my host during a year spent in England on a JoHn Sı-
MON GUGGENHEIM FELLOwsHIP — and Dr.R. J.G. SA-
VAGE, University of Bristol, gave me access to collec-
tions and provided stimulating discussions. Mr. R.F.
Pıckrord, Bath Geological Museum, helped in my
review of the Charles Moore collection.

The shaded drawings in the plates are the work of
Mr. A. J. LeE. Their preparation was made possible
by a grant from the Annıe M. ALEXANDER ENDOW-
MENT, Museum of Paleontology, University of Cali-
fornia Berkeley.

It is a great pleasure to acknowledge my hosts who
made it possible for me to work at the Institut für
Paläontologie und historische Geologie, Universität
München during the 1978-79 acadmic year. Prof.
Drs. Volker FanıguscH and Richard DEHM invited me
to work at the institute. I am deeply greatful to them
and to Prof. Dr. Dietrich Herm and Dr. Peter WELLN-
HOFER not only for professional assistance that greatly
advanced my studies, but also the warm hospitality
they extended to me and my family making it a
memorable stay. Finally, I wish to express my sincere
thanks and deep appreciation to the Alexander von
Humboldt-Stiftung for both providing me with a
“Senior U. S. Scientist Award” and their continuing
interest that added highlights to our year in Germany.

GEOLOEN ANDIBALEOGEOGRAPHY.

In a recent review of the Mesozoic records of mam-
malian evolution (CLEMENS et al., 1979) several
fossil localities in northwestern and central Europe
that have yielded the remains of primitive mammals
and advanced mammal-like reptiles were grouped
under the heading of sites of Late Triassic or Early
Jurassic age. These included the Rhaetic bonebeds at
Hallau, Switzerland, and in the Tübingen-Stuttgart
area of West Germany (BRD), a locality in the vicini-
ty of Nancy, France, and fossiliferous fissure fillings
in western England and Wales. Goals of the research
project reported here included reevaluation of the
data available in the literature concerning the German
and Swiss localities in order: 1) to arrive at a more
precise determination of their relative ages and their

temporal relationships to the French and British sites;
2) to summarize what is known of their taphonomy;
and 3) to place these local faunas in the context of
the major and rapid changes that occurred in the pal-
eogeography of Europe during the Late Triassic and
Early Jurassic. In following sections of this chapter
these data on the Swiss and German sites are sum-
marized and followed by a brief resume of informa-
tion concerning the French and British localities. For
various reasons it was not possible to reopen and
restudy the geological settings of the localities in
Switzerland and Germany.

The results of this review were far from satisfac-
tory. Clearly the period of earth history under con-
sideration is of short duration. The fossiliferous

deposits of interest are within the so-called Germanic
geological province (e. g., see Brınkman, 1960) that
during the Late Triassic was a largely continental area
and primarily a site of erosion or deposition of terre-
strial or shallow-water marine sediments. Contempo-
raneously, to the south in Tethys, considerable thick-
nesses of marine sediments accumulated. The Rhae-
tian was typified in this Tethyian (or Alpine) provin-
ce.

Development of understanding of the evolution of
the Germanic province and its faunas has been im-
peded by several obstacles. Possibly the most basic is
the proclivity of many workers to avoid distingui-
shing between lithologic, biostratigraphic, chronostra-
tigraphic, and chronologic units (see AGER, 1970).
Thus Mittlerer Keuper, or Middle Keuper, for
example, can be a designation for a very specific se-
quence of deposits in the Keuper basin of southwestern
Germany (BRD), a chronostratigraphic designation
for rocks deposited during the middle of the Late
Triassic, a designation for middle Late Triassic time,
or some mixture of these concepts (note PEARsOoN,
1970). Currently many workers utilize a sequence of
stages/ages based upon studies of the Tethyian Trias-
sic sequence as a standard scale of reference (note
papers in ZAPFE, 1974a, for example). However there
are uncertainties and disagreements concerning the
definition of Rhaetian and Norian in the Tethyian
province and utilization of these units in the Germanic
province (note PEARson, 1970, TOZER, 1974, ZAPFE,
1974a, and references cited). Palynological studies
(note SCHUURMAN, 1979) and research on ostracods
(note WıLr, 1969) offer promise of surmounting corre-
lation problems, but their resolution remains a goal for
future research. Without precise correlations it is
impossible to closely interrelate the evolution of the
terrestrial fauna with the physical changes in the Ger-
manic province, which was largely submerged during
the Rhaeto-Liassic transgression. What has emerged
from this work is a cloudy, hypothetical picture of
their coevolution.

For the purposes of this paper the following con-
cepts and units will be utilized with limited meanings.
These choices reflect a geographic bias. The Swiss and
German bonebed sites, which are the focus of this
report, were formed as the Keuper basin of south-
western Germany and northern Switzerland was
being filled and then flooded during the close of the
Triassic and beginning of the Jurassic. Definitions of
these concepts and units currently utilized by some
workers in this part of central Europe are favored
with the recognition that they can have significantly
different meanings in other areas and for other wor-
kers.

Hettangian: The base of the Hettangian (fre-
quently equated with the beginnings of the Liassic and

Jurassic) will be taken as the beginning of the Psilo-
ceras planorbis Zone. In this and in choice of sub-
sequent, younger units of the Liassic the scale present-
ed by Urrıchs (1977) for use in southwestern Germany
is followed. This definition of the base of the Hettan-
gian (or Lias) differs from that used by other workers
in northwestern Germany (e. g., Wırr, 1969) and sug-
gested for international adoption (e. g., PEARsonN, 1970)
in which a Pre-planorbis Zone or Beds is recognized
as the basal unit of the Hettangian.

Rhaetian: The complex history of the concept
of the Rhaetian has been reviewed by PEARson (1970,
also see TozEr, 1974, WIEDMANN, 1974, ZAPrFE, 1974b,
and SCHUURMAN, 1979). Currently there is an un-
resolved debate over whether the Rhaetian is properly
recognized as an age between the older Norian and
the Hettangian or is simply coeval with part of the
Norian.

Correlations have been attempted between the type
region of the Rhaetian in the Tethyian province and
sections containing shallow water to brackish marine
deposits formed in a different faunal realm in north-
western Germany (see Wırr, 1969, and SCHUURMAN,
1979). In Baden-Württemberg Rhaetic, Rät, or Up-
per Keuper, appear to have been used most frequently
to designate the sediments, contained faunas, and/or
an interval of time between the termination of depo-
sition of the Middle Keuper and the lowest stratigra-
phic occurrence of beds containing a Liassic marine
fauna. GEYER and Gwinner (1968) present a gener-
alized Rät section for Baden-Württemberg dividing
it into an Oberrät or Triletes-Schichten and an Unter-
rät or contorta-Schichten. On lithologic grounds the
bonebeds of the Tübingen-Stuttgart area might be in-
cluded in the Unterrät (Arrrer, 1974). How the
times of formation of the Rhaetic bonebeds in the Tü-
bingen region relate to the times of deposition of the
Hallau bonebed, the Lower Rhaetic of the Nancy
region, and the Rhaetian sections of northern Germa-
ny, Britain, and the Tethyian province remain open
questions.

Rhaetic: This term is used here in the limited
sense of a lithostratigraphic name. As will be argued
below, the time of formation of some Rhaetic bone-
beds might not be Rhaetian.

Middle Keuper: The uppermost lithostrati-
graphic unit of this sequence in Baden-Württemberg is
the Knollenmergel. BRENNER (1973) argued that it can
be considered as an essentially isochronous unit of
Norian age. How the time(s) of termination of depo-
sition of the Knollenmergel relate to the Rhaetian-
Norian boundary (or the Hettangian-Norian
boundary for those who reject the Rhaetian Age) is
not yet determined.

Rhaeticlocalfaunasofthe
Tübingen-Stuttgartarea

Although varying in thickness and sporatic in oc-
currence Rhaetic bonebeds are common elements of
the Rhaetic Sandstone (Rhätsandstein) in the vicinity
of Tübingen and Stuttgart and as far southwest as the
region of Täbingen and Balingen (Fig. 1). Within this
area the Rhaetic Sandstone is not a continuous unit
but consists of a group of usually thin, lenticular
bodies of sandstone separated by areas of Rhaetic
Clay (Rhätton) or regions where Rhaetic deposits are
lacking. Formation of the Rhaetic Sandstone has
been attributed to the development of prograding
deltas modified by longshore currents (AEPLER, 1974).

In 1847, after a painstaking search of minute fossils
concentrated by washing bonebed samples from expo-
sures south of Stuttgart at Degerloch and Steinen-
bronn, PLIENINGER announced his discovery of two
mammal-like teeth. One is now the type of the
haramiyid Thomasia antiqua; the other is a fragment
of a tritylodont cheek tooth. For the following 86
years, until 1931, discoveries of specimens of Rhaetic

FRANCE
Nancy
= St. Nicolas-du-Port

RS
N
&

Strasbourg 5

mammals or advanced mammal-like reptiles in bone-
beds of Baden-Württemberg appear to have been
limited to the recovery of fragmentary teeth of trity-
lodontid therapsid reptiles. Tritylodon fraasi Lydek-
ker, 1887, was typified on a tooth from Schlößlesmüh-
le bei Steinenbronn; the type of Chaleopotherium
plieningeri Ameghino 1903, might have come from
the same site. Hennig (1922) used a tooth from either
Schlößlesmühle or Olgahain as the basis of his concept
of Oligokyphus triserialis and a second specimen, cer-
tainly from Olgahain, was informally named O. biser-
ialis (see KÜHne, 1956). BrancA (1915), HENNIG
(1922) and Schmipr (1928) reviewed various aspects
of the vertebrate fauna of the bonebeds. Finally,
Sımpson (1928) presented a thorough analysis of the
small, pertinent sample in his monographic study of
the Mesozoic mammals of Europe.

During the summer of 1931 E. von HUENE pros-
pected a series of natural and man-made exposures of
Rhaetic bonebeds. Apparently she limited herself to
those that could be easily disaggregated and utilized
a binocular microscope to search through the material.
Rhaetic bonebeds at Sonnenberg bei Degerloch, Gais-

Stuttgart A

GERMANY
= Tübingen

Ne a

Balingen

Täbıngen =

x pone!

Sigmaringen

WÜRTTEMBERG

Hägendorf =

Figure 1:

SWITZERLAND

Sketch map of parts of northern Switzerland, southwestern Germany, and eastern France.

brunnen, and Olgahain proved to be the most produc-
tive. The results of her research were published two
years later (E. von HuEnt, 1933).

Subsequently, the only major attempt to sample the
microvertebrates of the Rhaetic bonebeds in the Tü-
bingen-Stuttgart area appears to have been that
undertaken by Prof. ©. H. SCHINDEwoLF of Tübingen.
Bonebed material was collected at Gaisbrunnen in
1947 and at Olgahain in 1948. Material from Olga-
hain was disaggregated and a fossiliferous fraction
concentrated by use of heavy liquid flotation. This
concentrate was subdivided by use of a series of
screens; the smallest was 0.5 mm mesh. Only part of
these concentrates have been sorted.

Since 1933 a few publications have dealt with the
mammals or advanced mammal-like reptiles from the
Rhaetic bonebeds of Baden-Württemberg. BUTLER
(1939) and Kühne (note particularly 1950, 1956) con-
sidered the morphology and taxonomy of European
tritylodonts.. KüHne (1950) concluded that Mucro-
therium cingulatum E. von HUENE and Uniserium
enigmaticum E. von HUENE were based on fragmentary
teeth of a tritylodont, probably Oligokyphus. Cur-
rently the specimens from the Rhaetic bonebeds of
Baden-Württemberg appear to document the presence
of no more than one species for which the name Oli-
gokyphus triserialis is appropriate. It should be noted
that Kühne (1956) justified recognition of two new
species of Oligokyphus, O. major and O. minor, mem-
bers of the Windsor Hill local fauna of England, on
apparent differences in the geological ages of the Eng-
lish and German sites and absence of sufficient data
demonstrating identity. HaHn (1973), in his review of
the haramiyids found in Germany (BRD and DDR),
described two teeth found in the collections made
under the direction of Prof. SCHINDEWOLF.

As discussed in the following section on haramiyids,
Schlößlesmühle bei Steinenbronn, once thought to be
the type locality of Thomasia antiqua, can no longer
be listed among the Rhaetic bonebed sites of Baden-
Württemberg yielding remains of mammals or ad-
vanced mammal-like reptiles other than tritylodonts.
Hennig (1922, Section D) reported additional disco-
veries of “mammalian teeth” from various localities,
some known e. g., Hohenheim and the valley of Gol-
dersbach near Bebenhausen, and others not recorded.
For various reasons — the specimens were not de-
scribed in sufficient detail and now are lost or were
shown to be referable to other kinds of vertebrates —
these will not be considered further. However, they,
other lost fossils (e. g., ZAHN G,, E. von HueENnE,
1933), and the small number of specimens of mammals
and mammal-like reptiles now available for study sug-
gest that the current sample surely does not document
the diversity of these animals in the Rhaetic bonebed
fauna. These rare fossils of mammals and mammal-

like reptiles (excluding teeth of tritylodonts) are now
known certainly from just three localities in Baden-
Württemberg:

Gaisbrunnen: The collecting locality was in
a quarry in the Rhaetic Sandstone lying between Be-
benhausen and Waldhausen, approximately 3.5 km
north of Tübingen. Although giving a description of
the lithology of the Rhaetic Sandstone, E. von HUENE
(1933) did not pay equal attention to the subjacent
and superjacent strata. She noted the occurrence of
four pelycepods (Pecten acutauritis, ?Myoconcha bey-
richi, Modiola minima, and Cardita praecursor) and
two ammonites, both represented by specimens of
juvenile individuals (Psiloceras [Waehneroceras] sp.
and ?Psilophyllites sp.) in the bonebed. The lithology
of the Rhaetic Sandstone was analyzed by AEPLER
(1974).

The Geologische Karte von Tübingen und Umge-
bung (1969, 1:50,000, Geol. Landesamt Baden-Würt-
temberg) shows that in the immediate vicinity of Gais-
brunnen the Rhaetic Sandstone lies on the Knollen-
mergel and is overlain by Lias @ ,+2. ALTMAN (1965)
described two nearby sections. In one (Section 35)
approximately 2 km southsoutheast of Gaisbrunnen, a
limestone directly above the Rheatic Sandstone
yielded a fragment of Psiloceras (Curviceras) aff.
subangulare. In a second (Section 37) approximately
1 km northwest of Gaisbrunnen the Rhaetic Sand-
stone is overlain by 2—5 cm of unfossiliferous marl.
On top of the marl is a limestone. Altman (ibid.)
reported the occurrence of Psiloceras planorbis and
Psiloceras plicatulum in the lower part of the lime-
stone. At higher levels he found Psiloceras (Caloce-
ras) johnstoni and Psiloceras (Curviceras?).

Olgahain: E. von Huene (1933) noted that her
collections came from part of the Rhaetic bonebed
exposed by the toppling of a large tree on the slopes
of Kirnberg above Olgahain, approximately 1 km
east of Gaisbrunnen. Again, although discussing the
lithology of the bonebed and Rhaetic Sandstone, she
did not review its geological setting. Probably it is
similar to that of Gaisbrunnen. Shells of two kinds of
pelecypods (Modiola minima and Leda deffneri) were
identified but she did not recover any remains of am-
monites.

Sonnenberg bei Degerloch: This collecting area is
approximately 25 km northnortheast of Tübingen in
the suburbs of Stuttgart. Haac (1928) relocated the
site where PLIENINGER presumably discovered the type
of Thomasia antiqua and described a second section
exposed about 500 m to the southsouthwest near Son-
nenberg. A few years later E. von HuEne (1933)
noted that this second section was covered over but
the overburden was removed in order to collect a
sample. Thus the type of Thomasia antiqua and the

fragment of a tooth collected by E. von HuEne and
here very tentatively referred to Tricuspes tubingensis
probably came from different localities in the region
of Degerloch.

E. von Hurne (1933) gives a geological section that,
though less detailed, can be reasonably correlated with
Haag’s (1928). Haas noted that the lowest unit
exposed in the section was the Knollenmergel. The
bonebed is shown to be overlain by: 1) a thin (1 cm)
red-brown to yellow-brown earthy mass, 2) Lias-
mergel (up to 1 m) and, finally, 3) the first limestone
of the Lias a. E. von HueEne (ibid.) reported the
discovery of a pelecypod, Pecten actauritis, and a
juvenile individual of the ammonite Psilophyllites at
Sonnenberg bei Degerloch.

At these three bonebed localities the Rhaetic Sand-
stone rests on the Knollenmergel, the stratigraphically
highest unit of the Middle Keuper. The upper Middle
Keuper was studied recently and intensively by
BRENNER (1973, 1978a, 1978b) from whose publications
the following summary is drawn.

During deposition of the upper Middle Keuper, in
the late Carnian and Norian, Baden-Württemberg and
Kanton Schaffhausen lay in the southern part of the
slowly but irregularly sinking German Keuper Basin
(note BRENNER, 1973, Abb. 19). Onearea of relatively
greater subsidence within this basin was centered in
the region just north of Sigmaringen (Fig. 1). The
sites of the fossil localities in the Tübingen-Stuttgart
area considered here lay in the northern part of this
area of subsidence; Hallau (Kt. Schaffhausen) in the
southern part. Sheet floods transported sediments to
the most rapidly sinking parts of the basin, which ap-
parently was quickly leveled. BRENNER (1978a) sug-
gested annual precipitation increased during the depo-
sition of the Knollenmergel and the climate became
semiarid to subhumid (annual precipitation 250 to
450 mm). Also, he (Brenner, 1973, note Tab. 2)
treated the Knollenmergel as an essentially isochro-
nous unit within the basin.

The genesis of bonebeds was studied in derail by
Reır (see 1976), AEpPLER (see 1974), and their col-
leagues. These studies based on thorough sedimento-
logical analyses, include a wide range of taphonomic
considerations. In this work bonebeds were simply
and generally defined as sediments with high concen-
trations of greatly fragmented and, usually, heavily
rolled bones. Frequently the fragments of bone are
well sorted and lie in the range of fine to coarse peb-
bles. Three categories of bonebeds were differentiated
on the basis of their place and mode of origin:

Condensation bonebeds formed in shelf areas where
the rate of sedimentation was low and fine sediments
were winnowed away from the bones.

Placer bonebeds deposited in deltas and other sites
of prograding sedimentation (e. g., channels).

Transgression bonebeds developed as lag deposits
during marine transgressions.

Of the German and Swıss bonebeds considered in
this report Gaisbrunnen and Sonnenberg bei Deger-
loch (Arprer, 1974) and, probably, Olgahain are placer
bonebeds. Most likely the Hallau bonebed is a com-
bination of a placer bonebed in part reworked during
a marine transgression, but its genesis needs further
analysis. Aeprer’s (ibid. and reports in preparation)
studies focus on the genesis of the Rhaetic Sandstone
and its bonebeds in the Tübingen area. The following
points directly pertinent to this analysis were extract-
ed from his work.

As already noted, the Rhaetic Sandstone occurs in
lenticular bodies, each probably the deposit of a pro-
grading delta modified by coastal longshore currents.
The Rhaetic Sandstone delta in the vicinity of Tübin-
gen is reconstructed as having had a low relief with its
terrestrial area broken up by many channels and shal-
low lagoons. The streams forming these deltas are
thought to have had their headwaters in low source
areas to the south and/or east and carried a relatively
small load of sediment, even in times of flood. They
flowed generally northward emptying into the shallow
sea that covered northwestern Germany during the
Rhaetian. During development of this and other del-
tas sea level appears to have remained relatively con-
stant.

AEPLER (ibid., p. 147, also see BRENNER, 1978a) sum-
marized evidence suggesting that after the intensive
aridity characteristic of most of Middle Keuper times
annual precipitation increased and the climate became
characterized by seasonal periods of intense rainfall
resulting in occasional flooding. Although dune sands
formed immediately along the coast, most of the delta
surface and coastal area was well vegetated with
major forests occurring upstream.

Formation of the placer bonebeds appears to have
been a two-stage process. As the animals living in and
around the streams and lagoons on the delta died their
skeletons settled in or were brought into these water
bodies. Initial fragmentation was primarily the result
of the activities of carnivores and scavengers. Once
submerged, the bones and teeth permineralized by
uptake of phosphates provided by decay of organic
material. The water in streams and lagoons on the
delta usually was either calm or slow moving. Only
the finest particles were winnowed away and a rela-
tively low amount of sediment was brought in from
source areas. Condensation bonebeds formed on the
delta surface. At times of flooding the permineralized
bones and teeth were transported and further frag-
mented, hydrodynamically sorted, and then deposited
as placer bonebeds in the channels or on the delta
front. Possibly the process of reworking on the delta
surface occurred several times before the bones and

teeth were entombed in the foreset beds of the pro-
grading delta.

This reconstruction of the sedimentary regime indi-
cates the fossils concentrated in the placer bonebeds
are a thanatocenose of the remains of aquatic (both
freshwater and, possibly, marine) and terrestrial or-
ganisms.

Although the possibility that some of the heavily
abraided fossils might be parts of mammals or mam-
mal-like reptiles that lived along the upper reaches of
the tributary streams and were washed down at times
of flood cannot be entirely ruled out, it seems more
likely they are parts of the inhabitants of the delta.

Determination of the geological age of the mammals
and mammal-like reptiles whose remains are preserved
in the bonebeds of the Rhaetic Sandstone in terms of
the standard European time scale remains an unat-
tained goal. This is not simply the result of problems
of correlation between the Tethyian and Germanic
provinces already noted, although these are major
contributing factors. AEPLER (1974) argued that the
development of a Rhaetic Sandstone delta was a slow,
complex process; probably one encompassing tens if
not hundreds of thousands of years. In this multi-
staged process many years might have passed between
the time an animal died and parts of its skeleton were
finally entombed in a bonebed. Thus, determination
of the age of a bonebed only sets a minimum age for
the time of existence of the animals represented in the
deposit.

On the basis of data currently available maximum
and minimum ages of the bonebeds at Gaisbrunnen,
Olgahain, and Sonnenberg bei Degerloch can be
established within a limited range. All three bonebeds
are parts of deposits laid down upon the Knollenmer-
gel. This is the uppermost unit of the Middle Keuper
and, following BRENNER (1973), can be assigned a
Norian age.

At the other extreme, the Tübingen-Stuttgart area
was largely if not fully submerged by marine waters
during the Hettangian. Although his geological sec-
tions do not include those of the Gaisbrunnen and
Olgahain localities, ALrman (1965) reports Psiloceras
planorbis and, slightly higher stratigraphically,
P. johnstoni, from a nearby section. Haac (1928)
did not record what, if any, ammonites were recov-
ered in the section at Sonnenberg bei Degerloch, but
reported the bonebed was capped by strata of Lias o,
i. e., early Hettangian.

AEPLER (1974) considered the implications of the
discovery of fragments of juvenile ammonites in some
bonebeds (e. g., those reported by E. von HuEne
(1933) from Gaisbrunnen and Sonnenberg bei Deger-
loch), and suggested that the time of formation of
these bonebeds might be correlative with the Pre-

planorbis Zone as recognized by Wırr (1969) in the
Liassic section of northwestern Germany.

Restudy of theRhaetic bonebeds, particularly inves-
tigations focused on recovery of ostracods and paly-
nological samples, might permit more refined correla-
tions. However, currently available data only war-
rant delimitation of a range of possible ages. The
mammals and advanced mammal-like reptiles repre-
sented in the bonebeds at Gaisbrunnen, Olgahain, and
Sonnenberg bei Degerloch most likely are no younger
than Hettangian. They might be of earliest Het-
tangian (Pre-planorbis or Psiloceras planorbis Zone),
Rhaetian, or latest Norian age. Probably they are no
older than Norian.

Hallau local fauna

The mammals and mammal-like reptiles of the Hal-
lau local fauna are known from fossils found at a
single locality in the Klettgau region of northern
Switzerland to the west of Lake Constance (Fig. 1).
The site, sometimes called Breitelen, is near the crest
of the Hallauerberg immediately to the northwest of
the town of Hallau (formerly designated Unter-Hal-
lau), in the western part of Kanton Schaffhausen.
Here the Rhaetic bonebed is not now exposed at the
surface, but probably occurs over an area of at least
1 kilometer’s length in a southwest to northeast di-
rection above the vineyards of Hallau. Apparently
this bonebed has only been seen in man-made excava-
tions.

Knowledge of the geology of the Hallau and adja-
cent areas stems from and in many respects still is
directly based upon results of the research of Bergrat
Dr. Ferdinand ScHALCH. SCHALCH’s interest in strata
adjacent to the boundary between the Keuper and
Lias is illustrated in his dissertation (SCHALCH, 1873).
Then and for many years thereafter it was commonly
held that Rhaetic bonebeds, or other Rhaetian depo-
sits, were absent from geological sections in a large
part of southwestern Germany (Baden-Württemberg)
and northern Switzerland. However, to the northeast
of a line drawn through Täbingen and Balingen in Ba-
den-Württemberg (Fig. 1) deposits of Rhaetian age,
including the Rhaetic bonebeds of the Tübingen-Stutrr-
gart area, were known to be well developed. To the
southwest of a line through Adelhausen in Baden-
Württemberg and Hägendorf bei Solothurn in Swit-
zerland Rhaetian deposits were also known to be pre-
sent in the geological sections.

SCHALCH was attracted to the section on Hallauer-
berg by a paper by Prof. MERKLEIN (1809), a professor
of natural history in the gymnasium in Schaffhausen,
who noted that a Herr HEnsLER reported a Keuper
bonebed was encountered during construction of a
road below the poor houses of Unter-Hallau (now the

site of a Bürgerheim, a home for the aged). In 1915
this site had long been covered over but the widening
of a farm road opened new exposures of Liassic depos-
its less than a kilometer from the spot where HENSLER
reported the bonebed. ScHarcH had a shaft sunk to a
depth of approximately 3 m and exposed the geologi-
cal section down to the Upper Triassic deposits. Part
of this section included the following units (from
PEYER, 1956, with emendations):

ScHALcH’s Thickness
alphabetic (meters) Unit
designations

m 2.5 Arietenkalk

l 0.23 Angulatusbank

k 5.35 Schwaichel (an ugly colored,
dark gray to brownish
green, irregularly
stratified, marly shale
with many finely
dispersed, calcareous,
sandy inclusions

i 0.20 Upper Psilonotenbank

h 0.70 marly shale, resembling the
Posidonienschiefer

g 0.14—0.17 Lower Psilonotenbank

f 0.04—0.05 black, impure marl with
abundant Liassic fossils

e 1.00 _loose marl bonebed with the
same (vertebrate) fossils
as unit d

d 0.25 compact Zanclodonmergel
breccia with bonebed

c 0.850 Zanclodonmergel resembling
unit a

b 0.20 beds with loaf-like
calcareous nodules

a 2.00+? ordinary, green and red-

spotted Zanclodonmergel

At SCHALCH’s invitation PEYER undertook analysis
of the vertebrate fossils found in the bonebeds (units
d and e). The blocks of compact bonebed (unit d)
were broken mechanically for inspection. Portions of
the friable sediment of unit e were spread out on
tables, carefully sprayed with water, and then sorted
with the aid of an eight or ten-power magnifying
glass. Not surprisingly fragments of very small mam-
mals or mammal-like reptiles were not discovered
during this project, although the remains of many lar-
ger vertebrates were recovered (see SCHALCH and
PEYER, 1919, and PEyEr, 1944a, 1944b, 1956).

In the autumn of 1942 a second shaft was sunk in
the vicinity of the earlier excavation. Over eight
metric tons of bonebed (probably this weight is for

material from unit e and excludes blocks of unit d
[Peyer, 1944 b, p. 306]) was collected and taken to
Zürich for preparation. The friable bonebed (unit e)
was dried, washed through screens (the smallest with
a 1 mm mesh [ibid.]) and the concentrates divided
according to grain size prior to sorting. Samples of
the material that passed through the smallest screen
were checked without the discovery of indentifiable
fragments of bones or teeth. The compact bonebed
(unit d) was left outdoors over winter to break down
and then processed and sorted. Sorting was carried
out with a binocular microscope and, in later phases of
the work, heavy liquids were employed to further con-
centrate the bone fragments. The first report on the
mammalian and mammal-like reptile remains (PEyER,
1956) was based on material found up to 1951, prior
to completion of sorting of the concentrates. PEYER
began preparation of a second report dealing with
materials collected subsequently, but unfortunately
this study was not completed before his death. Ex-
cept for a small amount of material preserved as
lithological samples in the Paläontologisches Institut
und Museum der Universität Zürich, all the rock col-
lected by P£ver has now been broken down, processed
and the concentrates sorted.

ScHAaLcH and PEyEr (1919) present the most tho-
rough, available analysis of the geological section ex-
posed in the Hallau excavations. PEyEr (1944b) added
observations made during the 1942 excavation. The
basal units (a through c) were first referred to the Zanc-
lodonmergel, which is now considered an alternative
name for the Knollenmergel (see ScHALcH, 1916, PEYER
1944 b, BRENNER, 1973). This allocation was made on
the basis of: 1) the position of the strata at the top of
the extensive Middle Keuper section, which except for
the Jurassic strata at the crest, forms most of the
Hallauerberg, and 2) their lithology. Other than a
small fragment of bone and another scrap of car-
bonaceous material (jet) no fossils were encountered in
these units during the 1915 excavation. However,
during the 1942 excavation bones of Gresslyosaurus
were found in unit c of the Zanclodonmergel (PEYER,
1944 b). The Zanclodonmergel is interpreted as a unit
deposited in nonmarine conditions and no evidence
from the Hallau site is contradictory.

The bonebed (units d and e) lies directly on the
Zanclodonmergel. ScHaLcH and PeEyer’s (1919)
initial basis for separating the two units was difference
in the degree of cementation, the particles of unit d
being bound together with a calcite or, rarely, barite
cement while those of unit e were not cemented.
Dominant particles of the bonebed are fragments of
limestone and marl (usually small, 1 to 2 mm in dia-
meter, but some were reported to reach a diameter of
16 mm). Almost all these appeared to be derived
from the Zanclodonmergel. Only a few were litholog-

ically distinet, but these could have been derived
locally from lower units in the Middle Keuper. The
absence of quartz was noteworthy.

In addition to fragments of limestones and marls
SCHALCH and PEYER (ibid.) noted the bonebeds contain
abundant carbonaceous fragments, pieces of bone, fish
and reptilian vertebrae, teeth, and coprolites. PEYER
(ibid.) provided the following list of genera and spe-
cies identified from the collections made in 1915
(many fragments were not identifiable at the generic
or specific levels):

Ceratodus parvus
Sargodon tomicus
Hybodus sp.
Hybodonchus sp. ?
Gresslyosaurus sp.
Termatosaurus albertii
Megalosaurus sp.

Also recovered were scales of ganoid fishes and
bones of nothosaurids and labyrinthodonts.

Later work by P£ver (1956) demonstrated that the
bonebed units (d and e) do not differ solely in hardness
but also in faunal content. Unit d, the compact
bonebed, lacks fragments of marine invertebrates and
probably was formed in a freshwater or brackish
environment prior to the time of the marine trans-
gression of the Hallau area. In contrast, in addition
to the vertebrate fossils, during the sorting of the con-
centrates obtained from the upper unit (e) fragments
of shells of mollusks, parts of crinoid stems, and
various skeletal elements of echinoderms were found.
PEver (ibid.) concluded these fossils represent animals
that were part of a typical lower Liassic marine fauna.
Unfortunately the presence of these fossils was not
recognized during collection of the rock. Some of the
invertebrates found in the concentrate might be con-
taminants, fossils that fellor were washed down from
exposures of unit f within the shaft. Although aware
of this possiblity, PEyEr (1944 b) suggested that many
if not most of them were derived from unit e.

Unit e now appears to be the product of partial
reworking of unit d with addition of more material
from the Zanclodonmergel during the transgression of
the sea. Reworking of the Keuper deposits and
bonebed continued in other regions providing sediment
to the Hallau area until the beginning of deposition of
the Upper Psilonotenbank (ScHALcH and PEver, 1919,
and PEYER, 1944 b).

I could not find any record distinguishing the fos-
sils of mammals or mammal-like reptiles that came
from unit d from those derived from unit e. Because
rock from both units was processed by PEYER, it is
reasonable to assume the rare teeth of these animals
occurred or appeared to occur in both. If the simpli-

fying, but not particularly justified assumption is
made that these teeth occurred in a random distribu-
tion throughout units d and e, then probably the ma-
jority of the fossils collected came from unit e for a
much greater volume of this unit was available and
processed.

The structure and composition of the bonebeds give
ample testimony to transport of material from other
areas and reworking of the fragments of rock and
vertebrate fossil. SCHALCH and PEYER (1919) and
PEyver (1944 b) tried to assess the degree to which these
process might have mixed materials from different
geological or biological sources. In the first paper
they note that some fragments of limestone and marl
show heavy abrasion suggesting considerable move-
ment in transportation or at the site of deposition,
others do not. There is equal diversity in the preser-
vation of the fossils. STROMER and PEYER (1917, p. 18)
commented that material of Ceratodus from Hallau
showed greater morphological detail and was more
complete than the heavily water-worn specimens
found in British Rhaetic deposits, e. g., Aust Cliff
near Bristol, or bonebeds in the Tübingen-Stuttgart
area.

In this study of the mammals and mammal-like
reptiles from Hallau no consistent differences in mode
of preservation or postmortem wear suggested a heter-
ogeneous sample derived from two or more sources of
distinctly different ages or distances from the site of
deposition. Lacking evidence to the contrary it is
tentatively assumed that these fossils can be treated as
representing members of a single local fauna (sensu
TEDFORD, 1970).

Although not a substitute for a thorough taphono-
mic analysis, which definitly is needed, the following
scenario is suggested. The formation of the Hallau
bonebed started with reworking of the uppermost
Zanclodonmergel by fresh or brackish water. Re-
mains of terrestrial and aquatic vertebrates, probably
parts of the local riparian and aquatic fauna, were
concentrated in a bonebed. What is left of this
deposit is now designated unit d. During the trans-
gression of the sea the upper part of the bonebed was
reworked. Fragments of marine invertebrates and,
possibly, freshwater or terrestrial organisms were
introduced to produce unit e.

Expression of the time of deposition of the Hallau
bonebed in terms of the units of a standard European
chronological scale cannot be made directly or with
great precision. SCHALCH and PEYERr’s (1919) assign-
ment of a Rhaetian age sparked considerable debate
(see PEyER, 1944 b). The second excavation at Hallau
provided some new information, but still did not
permit precise correlation. The currently available
data pertinent to this question can be outlined as fol-
lows:

The Knollenmergel, traditionally termed the Zanclo-
donmergel in reports on the Hallau bonebed, is the
uppermost unit of the Middle Keuper and thought to
have been deposited in the Norian (BRENNER, 1973).
The discovery of bones of Gresslyosaurus in unit c is
in accord with this view. Thus the age of the Hallau
bonebeds appears to be no greater than Middle
Keuper (Norian).

The compact, lower bonebed (unit d) lacks large
invertebrates that could be the basis for a correlation.
Fragmentary invertebrate fossils found in unit e in-
cluded no specimens that have been identified as
representing species of sufficient biostratigraphic util-
ity for the refined correlations needed. Also, they
might well represent organisms that lived after most
or all of the vertebrates represented in the bonebed.

PEvEr (1956) suggested the ganoid fish Sargodon to-
micus, the dipnoan Ceratodus parvus, and haramiyids
might serve as Rhaetian index fossils. Haramiyids
are now known to have existed from the Middle Keu-
per (Hann, 1973) into the Jurassic, possibly as late as
Bathonian (see CLemEns and KIELAN-JAWOROWSKA,
1979). Considering the kind of data on the biostrati-
graphic ranges of the fishes available to PEyer, their
utility as index fossils must be regarded as warranting
further testing. To the best of my knowledge studies
of ostracods, other microinvertebrates, or paleobotani-
cal material from the Hallau bonebeds have not yet
been attempted and the results published.

The bonebed is overlain by a black, impure marl
containing many fossils of Liassic marine invertebrates
(fide PEyER, 1956). Shells of ammonites identifiable at
the specific level were not discovered. However, in
the overlying Lower Psilonotenbank (unit g) an am-
monite referable to Psiloceras was discovered during
the 1915 excavation. Prof. PoMPEcKJ (quoted in
SCHALCH and PEyer, 1919) identified itasan Laqueolus-
form of the Psiloceras johnstoni group. Allocation to
Psiloceras johnstoni (or P. [Caloceras] johnstoni)
apparently has not been subsequently modified.

UrLicHs (1977) in his review of the Lower Jurassic
of southwestern Germany recognized the Psiloceras
planorbis Zone as the lowest zone of the Jurassic. In
stratigraphic sequence it is followed by the Psiloceras
(Caloceras) johnstoni, Psilophyllites hagenowi, and
Alsatites laqguens zones. These four zones comprise
the Lower Hettangian. The Lower Psilonotenbank
(unit g) is the lowest unit in the Hallau bonebed sec-
tion whose age of deposition can be correlated with
this sequence. "The occurrence of Psiloceras johnstoni
indicates an early but not earliest Hettangian age.

In summary, on the basis of the data currently
available all that can be said is that the Hallau
bonebed local fauna might be of Rhaetian age. It is
probably no older than Middle Keuper (Norian) and

no younger than the Psiloceras johnstoni Zone, early
but not earliest Hettangian.

Saint-Nicolas-du-Portlocalfauna,
France

The occurrence of vertebrate fossils in Triassic and
Liassic deposits of northeastern France has been
known for many years, but until recently none of
these fossils documented the presence of mammals or
advanced mammal-like reptiles. It should be noted
that instead of including it within the Triassic most
French stratigraphers usually classify the Rhetien as
the initial stage of the Jurassic arguing that it is the
time of the beginning of the major marine transgres-
sions of Europe that characterize the Liassic (note
Rıcour, 1961, PEARson, 1970).

In 1975 G. WOUTERs, screening sands in an old
quarry at Saint-Nicolas-du-Port, discovered a curious,
two-rooted tooth that might be an element of the den-
tition of an advanced mammal-like reptile (RusseLL
et al., 1976). Prompted by this discovery D. Sıco-
GNEAU-RusseLr (1978) undertook screen washing of a
large quantity of the fossiliferous sand. This unit is
part of a thick sequence of sandstones locally desig-
nated as Rhetien inferieur (note geological section
given by LAuGiEr, 1961). HOWEVER, as SCHUURMAN
(1977) cautioned such stratigraphic assignments have
been made on the basis of local lithostratigraphy and
might not have chronostratigraphic significance.

In a preliminary report SIGOGNEAU-RussELL (1978)
announced the discovery of isolated teeth of morganu-
codontids, possibly a docodont, kuehneotheriids, and
haramiyids. This work is being continued and gives
promise of providing the first large sample of a Rhae-
ticmammalian fauna from continental western Euro-
pe.

The systematic affinities of some of the mammals
reported to date will be discussed after description of
the materials from the Tübingen-Stuttgart area and
the Hallau local fauna. However, it is appropriate
to point out here that the only genera in common to
two or all three of the French, Swiss, and German
faunas are the haramiyids Thomasia and Haramiya.
These haramiyid “genera” are probably loosely
defined typological units for different kinds of teeth
and might bear little relationship to the genera of
animals represented. Thus, at our present state of
knowledge, it is only at the family or higher levels
that common occurrences of taxa in two or all three of
these faunas are recorded with some degree of cer-
tainty. Most likely these differences in faunal com-
position reflect both differences in age and the evolution
of insular faunas as the European continent was sub-
divided by epicontinental seas during the Rhaetian
and early Liassic.

Batenirrassıe aEarly Juvassic local
faunas from fissure fillings, western
Great Britain

In recent years most of our knowledge of Late
Triassic-Early Jurassic mammals has come from fossils
found in remarkable abundance in fissure fillings in
Wales and southwestern England. Three groups of
fissure fillings have yielded mammalian and advanced
mammal-like reptile remains that are of concern here.
First, the fissure fillings near the town of Bridgend in
Glamorgan, South Wales, include deposits that are the
source of immense samples of Morganucodon and
Kuehneotherium. These were exposed during opera-
tion of commercial quarries in Carboniferous lime-
stone. During the Rhaeto-Liassic this limestone
plateau is thought to have been an island, which
Rosınson (note 1971) dubbed St.Brides Island. Most of
the field research has been carried out by Dr. K. A.
KerMAcK and his associates at University College
London (see KErMACcK et al., 1973, for a history of
research).

A second group of fissure fillings are those exposed
in Holwell Quarry near Frome in Somerset, England.
In 1858 a fossiliferous fissure filling was discovered in
the quarry and Charles MoorE had over 3 tons of the
matrix transported to his home in Bath. Sorting this
matrix required over three years and yielded a wealth
of vertebrate material including a few isolated teeth
of haramiyids (note Durrın, 1978, and Pıckrorp,
1971). Subsequently fissures at Holwell were worked
by Kühne (1946) and SavacE and WALpman (1966,
also see Savage, 1971). Finally, another fissure filling
in Somerset, “Mendip 14”, at Windsor Hill Quarry
near Shepton Mallet has yielded an extensive sample
of Oligokyphus that was collected and studied by
Künne (1956).

As is the case with bonebeds, establishment of the
time of deposition of a fissure filling only sets a mini-
mum age for the contained fossils. Many of the pro-
cesses that have led to the concentration of bones in
fissure deposits are still poorly understood (note
Kermack et al., 1973). There is evidence suggesting
that some of the fissure deposits just cited might have
had developmental histories as long and complex as
the placer bonebeds (Reır, 1976).

The age of the fissure fillings and contained fossils
found near Bridgend, Wales, has been discussed
recently by Rosınson (1971) and Kermack et al.
(1973). Rosınson dealt primarily with age determi-
nations based upon a reconstruction of the physical
evolution of the Bristol Channel region. During a
later part of the Late Triassic (Norian), St. Brides
Island and several other areas composed largely of
Carboniferous limestones deformed by Hercynian
folding still rose as plateaus above extensive pied-

monts (note TUCkEr and BURCHETTE, 1977). At this
time the plateaus could have been ecological islands
supporting faunas and floras different from those of the
surrounding piedmont.

Starting in the Rhaetian and continuing in the
Liassic seas flooded the area and, apparently, during the
Sinemurian (Arietes bucklandi Zone) fully inundated
St. Brides Island. When during the period Norian to
Sinemurian the fissure fillings were formed remains an
unresolved question. Rosınson (1971) argued that
the narrow, slot fissures containing the vertebrate
fossils appear to be elements of a relatively immature
system of underground water courses. She suggested
this fissure system was cut after the seas had isolated
the island, raised the base level, and promoted the
evolution of new drainage patterns. “Just before
submergence sedimentation, rather than solution,
became the dominant process in these fissures (ibid.,
p. 136)”. She concluded that the fauna of the fissures
is largely of Liassic age.

Kermack et al. (1973) present a broader discussion
of the problem of age determination. They note that
the local faunas including Morganucodon and
Kuehneotherium occur in deposits containing other
vertebrates, occasionally invertebrates, and plants,
particularly remains of the conifer Hirmeriella (Chei-
rolepis) muensteri. To date this assemblage of organ-
isms, the Hirmeriella association, is only known from
fossil localities on St. Brides Island. Although little
help in precise correlations with other mammal-
bearing deposits, the distinctive composition of this
association supports the hypothesis that beginning
with ecological islands formed by highlands in arid to
semiarid environments and later isolated by Rhaeto-
Liassic seas many different insular faunas evolved.

Kermack et al. (1973) cite evidence suggesting the
fissure-filling local faunas are not as old as “Keuper”,
i. e., pre-Rhaetian. They conclude, “the age of the
Hirmeriella association in these fissures must be either
the Lower Lias (Hettangian and Lower Sinemurian)
or the Rhaetic. There is insufficient evidence to
decide between them.” To this can only be added
the observation that differences in composition of in-
dividual concentrations of bone within various fissures
might not be just a product of variations in taphono-
my but also reflect differences in age. The chronologi-
cal duration of the Hirmeriella association could
encompass a significant fraction of the Rhaetian to
Lower Sinemurian interval.

The specimens of haramiyids and Eozostrodon
found at Holwell Quarry were discovered in at least
two fissure fillings. These deposits are thought to be
neptunian dikes, submarine fillings of fissures opening
beneath the sea and, in some instances, close to shore
(Kühne, 1956, Rogınson, 1957, SAvAGE and WALD-
MAN, 1966). Künne (1946) reviewed faunal and geolo-

gical evidence and came to the conclusion that the
fissure fillings could have been formed sometime in the
interval from Rhaetian to Bajocian but favored a
Rhaetian age for the haramiyids and Eozostrodon.

In his monograph on Oligokyphus Kühne (1956)
presented thorough studies of the taphonomy and age
of the fossiliferous fissure filling in the Windsor Hill
Quarry, “Mendip 14”. Although a year or two might
have elapsed between the time of death of the indivi-
duals of Oligokyphus and the burial of their remains
in the submarine fissure, there is strong evidence this
interval was not significantly greater. Kühne (ibid.)
concluded that the age of the fissure filling and the
specimens of Oligokyphus was Charmouthian (Lias y
or Pliensbachian).

In summary, except for “Mendip 14”, currently
available data only warrant estimations of age ranges
of the fissure fillings and their faunas. (Both D. Pacey
and C. Durrın, University College London, have
undertaken studies of different aspects of the pro-
blems of determination of the ages of these and other
British Rhaeto-Liassic vertebrate localities). In the
cases of both the fissure fillings of St. Brides Island
and Holwell, the minimum ages of the vertebrate fos-
sils are well within the Liassic. If, following RoBın-
soN’s interpretation that sedimentation became the
dominant process in the development of the fissures
late in their history, then there is a possibility that
their local faunas are younger than the Rhaetic

bonebed local faunas of Switzerland, Baden-Württem-
berg, and France. The sample of Oligokyphus from
“Mendip 14” appears to be distinctly younger than
the genotypic species from Baden-Württemberg.

Paleogeography

During the early Mesozoic northwestern Europe
was of approximately triangular outline (see ZIEGLER,
1978). The base of the triangle was formed by exten-
sion movements leading to the development of a com-
plex graben system flooded by the Triassic, Tethyian
seas. Contemporaneously, to the west, the active rift
zones that would later produce the basin of the North
Atlantic Ocean and link it to the Arctic Ocean formed
the other side. The third side of the triangle was
delimited by the edge of the stable Russian platform
(Fig. 2).

In the Triassic the system of Permian basins within
northwestern Europe was modified by the develop-
ment of a new trough and graben complex. It was
an area largely characterized by erosion and, except
for the geographically limited transgression of the
Middle Triassic seas, deposition of terrestrial sedi-
ments. Toward the close of the Triassic most of
northwestern Europe had been reduced to an area of
relatively low relief, extensive flood plains, tidal flats,
and shallow basins separated by low hills and pla-

)
)

o
„8
3

(

N
\

Figure 2:

Schematic reconstruction of northwestern Europe showing areas covered by seas during

the Rhaetian transgression (Based on data from Wırr, 1969, ZIEGLER, 1978, MULLER, 1974, and T.R.
Owen, 1976).

teaus. The arid climatic conditions characteristic of
most of the Late Triassic (note Rosınson, 1973) were
ameliorated by increasing amounts of rainfall during
the Norian and Rhaetian.

At the beginning of the Rhaetian marked regional
extension movements, the Early Kimmerian tectonic
pulse, affected not only the North Atlantic to Arctic
and Tethyian rift systems but also northwestern Euro-
pe (ZIEGLER, 1978). This period of extension was the
prelude to the Rhaeto-Liassic marine transgression
that ultimately covered most of northwestern Europe.

Among the three areas of interest possibly the first
to be affected by marine transgressions were the parts
of Wales and southwestern England bordering the
Bristol Channel. Although the range of variation in
elevation was not great, the British Isles was an area
of relatively varied relief that waters from the proto-
North Atlantic probably quickly transformed into an
archipelago (note AUDLEY-CHARLESs, 1970 a und 1970b,
Donovan et al., 1979, and summary in T. R. Owen,
1976). By early Hettangian (Psiloceras planorbis
Zone), if not earlier, St. Brides Island could have been
fully encircled by marine waters (Rosınson, 1971).
Its fossiliferous fissure fillings were formed sometime
after the beginning of the Rhaetian but before final
submergence of the island in the Lower Sinemurian.
The fissure fillings at Holwell might also have been
formed during this interval, but the “Mendip 14”
fissure filling is younger (Pliensbachian).

During the Rhaeto-Liassic transgression what are
now the continental parts of northwestern Europe
were characterized by three major areas of erosion
(note Wırr, 1969, Figs. 47—49, ZIEGLER, 1978, Figs. 3
and 5, and Fig. 2). The Gallic High included, in
varying combinations, parts of southeastern England,
Belgium, and northwestern France (i. e., London-
Brabant Massif, Ardennes High, Armorican High, and
adjacent areas). To the northeast was the stable area
of the Russian Platform (including the Fennoscandi-
navian Shield). Finally, in the southeast the Vindeli-
zian High occupied parts of what are now north-
western Switzerland and southern West Germany.
To the northeast it was linked to the Bohemian Mas-
sif.

Marine waters flooding the basins of northwestern
Europe came primarily from the proto-North Atlantic
Ocean. They transgressed in a generally eastward
direction from the area of the British Isles flooding the
basins between the Gallic High and the Russian Plat-
form. A lobe of this sea expanded from the northeast
toward the west and south into the Paris Basin. Early
in the Rhaetian it breached the Gallic High in the
vicinity-of the modern Seine River valley and estab-
lished a connection with seas in southern England
(MuLter, 1974). Farther to the south a connection
with Tethys was established (Wırr, 1969).

The transgression of northern Germany came to a
halt or slowed toward the end of the Rhaetian pro-
viding a stable sea level, one condition thought to be
requisite for the development of the Rhaetic Sand-
stone deltas of the Tübingen-Stuttgart area (AEPLER,
1974). The streams forming these deltas had their
headwaters in the Vindelizian High. Surface out-
crops of the Rhaetic Sandstone containing bonebeds
are known from the region of Stuttgart southwest to
the Täbingen-Balingen area. Wells drilled in the
vicinity of Lake Constance have encountered Rhaetic
sediments that thin westward (Bücht et al., 1965). An
approximately north-south trending high from the
Aar Massif in the south, through the region of Zürich
and into the Schwarzwald of southwestern Baden-
Württemberg formed a peninsula into the Rhaetic sea.
On the western side of this peninsula, i. e., west of the
Adelhausen-Hägendorf line (Fig. 1), sediments includ-
ing bonebeds were also deposited during the Rhaetian
(note TANNER, 1978).

Arprer (1974) developed two working hypotheses
concerning the chronology of development of the
Rhaetic Sandstone deltas in Baden-Württemberg.
One (note ibid., Abb. 12) suggests that the deltas were
deposited in sequence as the seas transgressed, and,
therefore, from the oldest in the Stuttgart area the
Rhaetic deposits become progressively younger south-
westward. The Rhaetic Sandstone in the Tübingen
area is overlain by sediments of the Psiloceras planor-
bis Zone. However, the first Liassic ammonite found
above the Hallau bonebed is P. johnstoni. It is temp-
ting to hypothesize the bonebeds of the Tübingen-
Stuttgart area are somewhat older than the Hallau
bonebed. This might be the case. But, as AFPLER
(ibid.) noted, the available data from Baden-Würt-
temberg are also in accord with a hypothesis that the
Rhaetic Sandstone deltas developed at about the same
time throughout this area.

How the time of deposition of the bonebeds at
Saint-Nicolas-du-Port relates to that of the Swiss and
German bonebeds remains unclear. If the assignment
of a Lower Rhaetian age proves correct and Will’s
paleogeographic map of the area for the time of the
contorta-Schichten (Wırr, 1969, Fig. 49) is reasonably
accurate, the bonebeds of Saint-Nicolas-du-Port were
formed on the eastern margin of the Gallic High.
This area was then separated by a marine strait from
the shores of the Vindelizian High.

In summary, a review of biostratigraphic studies of
Rhaeto-Liassic stratigraphy of northwestern Europe
does not result in a marked increase in precision of
correlation of the vertebrate localities. In recent
years detailed palynological research and studies of
ostracods have added to development of a biostrati-
graphic framework. However these research techni-
ques have yet to be applied in renewed investigations

of the vertebrate fossil localities and the results pub-
lished. The fissure fillings of St. Brides Island and
Holwell Quarry, and the Rhaetic bonebeds of Saint-
Nicolas-du-Port, the Tübingen-Stuttgart area and
Hallau can be correlated with no more precision than
to say that they all are of Rhaeto-Liassic age.

To speculate, making use of the probabilities and
educated guesses of specialists, it can be argued that
the oldest occurrence of a haramiyid is that from the
probably Norian, Plateosaurus beds of Halberstadt
(Hann, 1973). If the assignment of Rhe£tien inferieur
has more than local significance, the Saint-Nicolas-du-
Port local fauna would be the oldest assemblage of
mammals yet found in Europe, and possibly the

world. The mammals from the bonebeds of Germany
and Switzerland might be slightly younger but no
younger than early Hettangian. Heavily weighting
Rosınson’s (1971) argument that the filling of the
fissures at St. Brides Island occurred close to the time
of the island’s final inundation in the Sinemurian,
these local faunas could have a Hettangian-Sinemu-
rian age. The Holwell local fauna might fall in this
interval. The differences in faunal composition dis-
tinguishing it from those on St. Brides Island could be
a product of insular evolution rather than differences
in age. Probably both factors are involved. Finally,
the rich accumulation of bones of Oligokyphus at the
“Mendip 14”, Windsor Hill quarry appears to be
even younger, Pliensbachian.

FOSSILS FROM THE TÜBINGEN-STUTTGART AREA
BADEN-WÜRTTEMBERG, WEST GERMANY

Introduction

Unlike the sample of the Hallau local fauna that
was collected at one site, the fossils described here
come from various exposures of the Rhaetic bonebeds
in the Tübingen-Stuttgart area. Currently available
data, reviewed in a preceding section, suggest they
are derived from approximately contemporaneous
sites formed under similar depositional regimes. For
these reasons, and convenience, the systematic analy-
ses of these few fossils are grouped in the following
section. Whether they actually document members of
one faunal unit remains to be determined.

Systematics

Class ?Mammalia
Order and Family incertae sedis
Tricuspes E. von Huene, 1933

Type species: Tricuspes tubingensis E. von
Huene, 1933

Revised diagnosis: In comparison to the
approximately contemporaneous morganucodontids,
cheek teeth are of larger size and simpler morphology
consisting of only three main cusps. 'The median or
principal cusp is larger than the anterior and posterior
accessory cusps. These cusps are not aligned directly
behind one another, but the apex of the principal cusp
is slightly buccal(?) to a line. drawn through the apices
of the anterior and posterior accessory cusps. A small
cusp may be present on the presumed posterobuccal
side of the crown. Directly below the crown the root

is bilobed in cross section and might have been fully
subdivided farther from the crown.

Distribution: Type locality: Gaisbrunnen,
Baden-Württemberg, West Germany. Referred ma-
terial from the following localities: Sonnenberg bei
Degerloch, Baden-Württemberg; Hallau, Kanton
Schaffhausen, Switzerland; and Saint-Nicolas-du-Port
district of Meurthe-et-Moselle, France (pers. comm.,
D. SIGOGNEAU-RUSSEL).

Tricuspes tubingensis E. von HUENE, 1933

Revised diagnosis: As for the genus until
additional species are recognized.

Type specimen: An isolated tooth tenta-
tively identified as a right lower molariform now in
the collections of the Geologisch-Paläontologischen In-
stitut der Universität Tübingen (see E. von HUENE,
1933, Taf. I, Fig. 7, and Pl. 1:1—2).

Orientation: On the basıs of several tenuous
assumptions the type specimen is identified as a lower
right molariform tooth (Pl. 1:1—2). A survey of
teeth of the known Triassic and Jurassic mammals
shows that usually, but not always, the lower molari-
form teeth have crowns higher (maximum cusp height
relative to crown height) than those of the uppers.
In many species cingula or cusps lateral to the main
cusps are found on only one side of the lowers but on
both sides of the uppers. These criteria, assumed to
be applicable to Tricuspes, are the basis for identifica-
tion of the type specimen as an element of the lower
dentition.

In many molariform teeth of triconodont-type and

known orientation, the anterior accessory cusp is low-
er than the posterior. Also, the anterior slopes of the
main cusps tend to be more gradual and slightly con-
vex in lateral outline. These two lines of evidence are
the basis for the designation of the anterior end of the
crown.
Identification of the type specimen as a right, rather
than a left lower cheek tooth is almost an arbitrary
choice. Two criteria are available for consideration,
the angulation of the row of main cusps and the orien-
tation of the small lateral cuspule. On lower molari-
form teeth of a tribosphenic or pre-tribosphenic pat-
tern and some triconodont-like teeth (note Ampbiles-
tes, see Mills, 1971, p. 53-4), the apex of the principal
cusp lies labial to the anterior and posterior accessory
cusps. Second, lateral cingula or cusps are usually on
the lingual side of the crown of lower molars. Thus,
by the first criterion, the type of Tricuspes tubingensis
is probably from the right dentition, by the second it
is a left molariform. The first criterion is slightly
favored because it might prove to be a more stable
feature. A very similar tooth in the collection from
Hallau lacks the lateral cusp, but shows the angulation
of the main cusps.

Description: The root(s) are broken away
leaving a fracture surface with a figure-eight outline
showing subdivision of the pulp cavity. The crown
appears to be well preserved and lacks evidence of
wear facets of post-mortem abrasion (Pl. 1:1—2).
A high principal cusp dominates the relatively simple
crown. The anterior accessory cusp is lower than the
posterior and both are separated from the principal
cusp by distinct notches. A slight bulge at the base
of the crown extends from the posterior end of the
tooth around the presumed lingual side of the posteri-
or accessory cusp. This swelling does not appear to
have been the base of a distinct cingulum nor did it
support cingular cusps. The fourth cusp on the crown
is a small but distinct cuspule on the posterobuccal
slope of the principal cusp. If the assumed orienta-
tion is correct, this is not a kühnecone, a cusp on the
lingual margin of the crown.

Dimensions of the type specimen are as follows:
crown length = 2.64 mm, width = 1.12 mm.

Discussion: A fragment of tooth described
and illustrated by E. von HuEne (1933, p. 84—5, Taf. I
Fig. 9), found in the Rhaetic bonebed at Sonnenberg
bei Degerloch, might be referable to Tricuspes tubin-
gensis. The fossil appears to be less than half of a
two-rooted tooth slightly larger than the type. Al-
though having suffered some further damage since its
original description, what little remains of the crown
is not strikingly different from the posterior part of
the crown of the type of T. tubingensis. If this identi-
fication is correct, then the specimen shows that some

teeth of T.tubingensis were supported by two separate
roots.

In her study E. von Huene (1933, Taf. III, Figs, 40,
41, 42, 44, 48) figured five fossils and described seve-
ral more from the collections of Charles Moore, now
housed in the Bath Geology Museum, Bath, England
(see Pıckrorn, 1971, Durrin, 1978). The figured spe-
cimens — a tooth, three vertebrae, and a phalanx —
were identified as coming from the Rhaetic site “Vallis
bei Frome’”’ and not from the fissure fillings in Holwell
Quarry. Of these fossils E. von HUENE referred the
tooth to Tricuspes; the bones were tentatively alloca-
ted to an undescribed, primitive crocodilian. Cata-
logue numbers were not recorded and, because of the
turbulent history of the collection during and after
World War II (see Pıckrorp, 1971), these bones cannot
now be certainly identified.

The illustration (E. von Huene, 1933, Taf. III,
Fig. 40) of the tooth referred to Tricuspes shows a
three-cusped crown supported by a single, blunted
root. Crown length, measured from the illustration,
is on the order of 1.4 mm. The accuracy of this
drawing cannot be directly assessed, but clearly its
shading is not rendered with the same care and detail
used in the drawings of the type of Tricuspes or teeth
of Oligokyphus.

Search of the Moore collection in 1975 resulted in
discovery of only one tooth that could possibly have
been the model for E. von Huene’s illustration. It
(C108) is a single-rooted tooth with a transversely
flattened crown of 1.6 mm anteroposterior length. On
either side of the principal cusp are small anterior and
posterior accessory cusps. Below each accessory cusp,
at the level of maximum length of the crown, are
minute cusps, only easily visible with magnification.
This fossil is identified as coming from Holwell Quar-
ry. It resembles those from Hallau described by
PEver (1956, p. 56—59) as, “Zähne von wahrschein-
lich Synapsiden Reptilien, Gruppe a”.

Thus, the tooth from “Vallis bei Frome” allocated
to Tricuspes by E. von HUENE cannot be certainly
relocated. The only fossil in what remains of the
Moore collection that might have served as the model
for her drawing is C108, which is recorded as coming
from Holwell Quarry, not from the site at Vallis. It
differs from the type of Tricuspes in its smaller size,
morphology of cusps, proportions of the crown and
undivided root. If found at Hallau, C108 would be
included in “Gruppe a” of the teeth tentatively al-
located to synapsid reptiles by PEyEr (1956).
However, the possibility that C108 was not the model
for her drawing and the illustrated tooth was lost
when the Moore collection was rapidly packed for
storage cannot be dismissed. In summary, there is no
unequivocal evidence that Tricuspes was part of the
British Mesozoic fauna.

Family Haramiyidae

In addition to being represented in local faunas of
the Tübingen-Stuttgart area and the Hallau local fau-
na, haramiyids are members of other continental
European and British local faunas. Most of these
records of haramiyids come from sites of Rhaetic or
Liassic age, but a tooth is known from a locality in
the Late Triassic, Keuper (Norian), Plateosaurus-
Schichten (Hann, 1973). FREEMAN (1976) reported
the occurrence of an isolated tooth in Bathonian (mid-
Jurassic) deposits in England that might have been
part of the dentition of a late haramiyid or an early
multituberculate. In spite of their widespread geo-
graphic and stratigraphic distribution in Europe, at no
site yet discovered has a large sample of haramiyids
been recovered. The group remains known from only
isolated, usually fragmentary teeth. If only complete
teeth or major fragments are counted, the total
haramiyid sample consists of approximately fifty
specimens (see Clemens and Kielan JaAwoRowsKA,
1979, for review).

The currently utilized classification of haramiyid
genera and species has not changed greatly from that
proposed by Sımpson (1928). Two genera are
recognized, Haramiya (= Microlestes, Microcleptes)
and Thomasia, which are distinguished on the basis of
number and relative size of cusps. In addition to the
four species formally recognized by Sımpson (1928) —
Haramiya moorei, H. fissurae, Thomasia antiqua, and
T. anglica — several unnamed “taxa” have been
noted (see HaHn, 1973) or morphological variants
described (PARRInGTon, 1947). Currently there is no
basis for determining whether these formal and
informal groupings represent collections of teeth of
different species or are simply associations of morpho-
logically similar teeth. Prof. P. M. BuTLer and
Dr. Giles MAcINTYRE (pers. comm.) are now engaged
in research on occlusal patterns of haramiyid denti-
tions that might contribute to the resolution of some
problems of classification. For the limited purposes
of this analysis the “taxa” of haramiyids are treated
as though they are based on collections of morpholog-
ically similar teeth that might be samples of different
biological species. The difficulties encountered in
assignment of some fossils strongly suggest they are
not, but do not clearly offer the basis for an alter-
native classification.

In the following descriptions the terminology sug-
gested by Hann (1973) is employed. Briefly, Row A
is the row of cusps of higher average height, which
usually are three in number. Row B, usually consists
of four or more cusps most of which are smaller than
the cusps in Row A. The “U-shaped rim” is the low
ridge connecting the two rows of cusps at one end of
the central basin. At the other end of the crown, the
higher cusps of Rows A and B are frequently linked

by a saddle marking a terminus of the central basin.
As a convenience in preparing descriptions, the “U-
shaped rim” is assumed to be at the posterior
end of the crown.

Thomasia Poche, 1908

The diagnosis of this genus currently utilized is that
proposed by Sımpson (1928, p. 63):

“Microcleptidae [= Haramiyidae] with one rim
of basined molar teeth [Row A] with three
tubercules of which the anterior is markedly the
largest and the posterior one may be much
reduced. The anterior cusp of the other side
[Row B] is not as high as that just mentioned,
and is followed by four or more smaller cusps,
the most posterior of which forms part of the
posterior closure of the basin [“U-shaped rim”].

Currently two species of Thomasia, T. antiqua
(Plieninger, 1847) and T. anglica Simpson (1928), are
formally recognized, but Hann (1973) also described
teeth under the rubrics of Thomasia sp. 1 and sp. 2.
As the name suggests, T. anglica is typified on and was
known only from specimens found at Holwell Quarry,
England.

Thomasia antiqua (Plieninger, 1847)

Sımrson (1928) reviewed the confused history of
the fossils originally referred to Thomasia antiqua by
PLIENINGER (1847). In 1979, with the assistance of
Dr. Rupert Wırp, I reviewed the Rhaetic bonebed
material in the collections of the Staatliches Museum
für Naturkunde, Stuttgart. The original descriptions
of the two teeth allocated to what is now Thomasia
antiqgua are in a paper (PLIENINGER, 1847) dealing with
fossils from the bonebeds at Degerloch and Steinen-
bronn. PLIENINGER did not record which of the locali-
ties yielded the specimens of Thomasia. HENNING
(1922) argued that the type specimen probably came
from Schlößlesmühle bei Steinenbronn and was fol-
lowed in this by Simpson (1928), Hann (1973), and
CLEMEnS et al. (1979). However a note now with the
fossils that apparently was written by Prof.
Dr. F. BERCKHEMER, the former curator of the Stutt-
gart paleontological collections, indicates that this is
not the case. BERCKHEMER cites the autobiography of
Herr Eser, a contemporary and friend of PLIENINGER,
in which it is stated that the type was found at Deger-
loch. Also, in his study of Belodon Plieninger (1852,
p. 428, footnote) notes that the fossils came from the
Grenzbreccia (= Rhaetic bonebed) at DEGERLOCH. As
pointed out in the section on Geology and Paleogeo-
graphy, PLieninger’s locality is approximately
0.5 km away from Sonnenberg bei Degerloch a site
worked by E. von HUuEnE.

In addition to the type PLIENINGER (1847) described
a second, similar, but somewhat larger tooth. Cur-
rently the collection contains several small pieces of
bonebed that are labled, “Microlestes antiguus Plien.,
verletztes Orig. z-PLIENINGER, Jahresb. 1847, Taf. I,
fig. 4”. A cusp and part of the base of a tooth are
preserved in one of the fragments. The size and con-
figuration of the cusp suggests it is part of the second
specimen and part of a tooth of Oligokyphus.

The hypodigm of Thomasia antiqua, as revised by
Hann (1973), consists of two isolated teeth, the type
specimen and GIT 1430/1. Their dimensions are as

follows:

Length (anteroposterior) Width
Type 2.1 1.3
GIT 1430/1 1.7 1.0

E. von Huene (1933) referred two teeth found at
Gaisbrunnen to “Microcleptes?” One (see ibid., Taf. I,
Fig. 6) now is lost. The illustrations of this specimen
suggest some similarities to teeth that have been ten-
tatively identified as haramiyid incisors. The second
specimen, which she identified as “Microcleptes (?) sp.”,
is a heavily worn haramiyid molariform (see ibid.,
Taf. I, Fig. 4) that is designated ?Thomasia sp. and
described below.

Collections from the Rhaetic bonebed exposed at
Olgahain, made in 1948 under the direction of Prof.
©. H. SCHINDEWOLF, contain three teeth of haramiyids.
Two were described by Hann (1973) and identified,
respectively, as Thomasia antiqua (GIT 1430/1)
and Thomasia sp. 2 (GIT 1430/2). The third specimen
(GIT 1541/1), described below, is another heavily worn
molariform that can be tentatively referred to Thoma-
sia.

Thomasia sp. 1 is based on a single molariform
found in the Plateosaurns-Schichten of the upper mid-
dle Keuper near Halberstadt (Hann, 1973). At the
moment this fossil provides the oldest record of the
Haramiyidae, and possibly the Mammalıia.

? Thomasia sp.

Description: The crown of the haramiyid
found at Gaisbrunnen and described by E. von HuENE
(1933, Taf.I, Fig.4) is heavily abraided (Pl. 1:4).
Except for the lining of its basin and small parts of
the margin of the crown, most of the enamel has been
removed. However, large parts of the two roots are
preserved. The almost complete root under the basin
is transversly broader than the other. Starting at

about the vertical midpoint of the broader (?posterior)
root and continuing to the base of the crown, a bony
septum links the roots. Dimensions of the crown are
as follows: length = 1.17 mm, width = .99 mm.

The enamel-lined basin occupies less than half of
the occlusal surface of the tooth. Its rim is not com-
plete but interrupted by a notch near the end of the
crown over the broader root. The cusps have been
worn away. What remains of their bases suggests the
basin was closed at the other end of the crown by a
major cusp or cusps. It can be argued, but not force-
fully, that the basin was situated toward the posterior
end of the tooth, its “U-shaped rim” was breached by
wear, and the mound at the other end of the crown
was formed by the bases of the anterior cusps of Rows
A and B. This orientation would place the smaller
root at the anterior end of the crown.

The third haramiyid specimen (GIT 1541/1,
Pl. 1:3) collected under the direction of Prof.
SCHINDEWOLF at Olgahain is more heavily worn than
the others. Dimensions of its crown are as follows:
length = 1.63 mm, width = 1.35 mm.

Large, apical wear facets mark the positions of the
anterior two cusps of Row A. Unlike typical molari-
form teeth of Thomasia the first cusp of this row was
about the same basal diameter and not significantly
larger than the second, and these cusps are well
separated. The third cusp of Row A appears to have
been much smaller, a character of some teeth referred
to Thomasia (Sımpson, 1928).

The cusps of Row B are almost completely obliter-
ated by a wear facet that slopes laterally at a low
angle and is likely the result of greater development of
facets of the kind illustrated by Hann (1973, Fig. 1d).
A small shelf at the front of the crown could be what
remains of an anterior cusp. The enamel has been
removed from the anterior end of the median valley.
This appears to have been initiated by a wear facet
that did not breach the “U-shaped rim”. Only their
bases are preserved, but these suggest the tooth was
supported by a larger, broader, anterior and a smal-
ler, posterior root.

Discussion: In summary, the current record
of haramiyids from the Tübingen-Stuttgart area
includes fossils from the Degerloch, Gaisbrunnen, and
Olgahain localities. The taxa, or morphologically
defined units, recognized are: Thomasia antiqua, Tho-
masia sp. 2 (Hann, 1973), and ?Thomasia sp. The
small collection contains no evidence of the presence
of Haramiya, but this could easily be an artifact of
the small sample size.

HAELAU LOCAL FAUNA, KANTONISCHAREHAUSEN
SWITZEREAND

All the fossils from the Rhaetic bonebed at Hallau
discussed here are in the collection of the Paläontolo-
gischen Institut der Universität Zürich, and are part of
the material obtained in a project carried out under
the direction of Prof. Bernhard PEyEer. To the best of
my knowledge this is the only collection of small
vertebrate fossils to be assembled from this locality.
Descriptions of more than half the fragments of teeth
of mammals or mammal-like reptiles in the collection
were presented in a major monograph by PEYER
(1965); the remainder is described here.

Systematics

Class Reptilia

No attempt has been made to thoroughly review
the records of reptiles in the sample of the Hallau
local fauna. However in going through the collec-
tions two points worthy of note became apparent.

Order Pterosauria

The teeth of most known pterosaurs are simple,
conical structures that probably are only certainly
identifiable when found in association with larger
elements of the skull (see WELLNHOFER, 1978). In con-
trast, the dentitions of the few pterosaurs discovered
in strata of Late Triassic (Norian) age include multi-
cusped cheek teeth. Some of the cheek teeth of the
Norian pterosaur Eudimorphodon Zambelli, 1973
(and see Wırp, 1979) have crowns made up of as
many as five cusps aligned anteroposteriorly and on
first inspection resemble teeth of members of the mam-
malian order Triconodonta.

Dr. Rupert Wıro, who has just completed a detailed
study of Eudimorphodon, reviewed the illustrations of
triconodont-like teeth in PEyEr’s (1956) monograph.
He noted (pers. comm.) that some of the teeth PEyEr
designated “wahrscheinlich synapside Reptilien,
Gruppe b” showed striking resemblances to cheek
teeth of Eudimorphodon [for example: AIII-301
(Pever, 1956, Taf. 12, Fig. 47), AIII-312 (ibid., Taf. 2,
Fig. 58), and AIII-321 (ibid., Taf. 10, Fig. 67)].
Other teeth from Hallau that PEYEr included in
“wahrscheinlich synapside Reptilien, Gruppe a”
resemble cheek teeth of a new, second genus of Norian
pterosaur (Wırp, 1979) and the Hettangian genus
Dimorphodon [for example: AIII-272 (ibid., Taf. 9,
Fig. 18), AIII-288 (ibid., Taf. 9, Fig. 34), AIII-320
(ibid., Taf. 5, Fig. 66), and AIII-322 (ibid., Taf. 10,
Fig. 68)].

These teeth from Hallau share several morphologi-
cal differences from the primitive conical pattern. In
lateral view their crowns are relatively high (height
of central cusp relative to anteroposterior basal
length) and generally triangular in outline. Two,
four, or possibly six (AIII-321, PEver, 1956, Taf. 10,
Fig. 67) cusps are symmetrically arranged on the
anterior and posterior edges of the main cusp. On
some teeth ridges on the lateral slopes of the cusps
extend toward, but do not reach the base of the crown.
No basal cingula are present. In occlusal view the
teeth exhibit relatively little lateral expansion. As
far as known all were supported by a large, single root
(for example, AIII-320, ibid., Taf. 5, Fig. 66).

Dr. WıLp’s notations of morphological resem-
blance should not be interpreted as positive identifi-
cations of different genera of pterosaurs in the Hallau
local fauna. Much more detailed research on the
morphology and patterns of variation (both onto-
genetic and individual) must be completed before
identification of different pterosaur genera on the
basis of isolated teeth can be attempted. PEYEr (1956)
is not alone among vertebrate paleontologists faced
with the problem of identifying isolated, somewhat
triconodont-like teeth of Late Triassic or Early Juras-
sic age who asked the question, are they teeth of
primitive mammals or advanced mammal-like repti-
les? Dr. WıLp’s observations require that the ques-
tion now be phrased, are they teeth of primitive
mammals, advanced mammal-like reptiles, or ptero-
saurs?

Order Therapsida

Family Tritylodontidae

The absence of identifiable remains, particularly
fragments of teeth, of tritylodonts in the sample of
the Hallau local fauna warrants special emphasis.
These advanced mammal-like reptiles are common
members of several Late Triassic and Early Jurassic
local faunas. The possibility that their absence is the
result of post-mortem sorting of skeletal elements ac-
cording to size, either during deposition of the bone-
bed or collection, probably can be dismissed. A sur-
vey of part of the collection of bone fragments picked
from the washing concentrates obtained at Hallau and
samples of the original bonebed matrix revealed pieces
of bone much larger than the cheek teeth of any
known tritylodont. At the other end of the size
range, isolated, individual cusps of teeth of morganu-
codontids and haramiyids, much smaller than the
major cusps of tritylodontid cheek teeth were recov-

ered. No fragments of teeth preserving the easily
recognizable, selenodont-like cusps of tritylodonts are
present in the collection. Thus, it seems most likely
that the absence of tritylodontids is the result of bio-
geographic or ecological factors rather than post-
mortem sorting of the bone.

Class ?Mammalia
Order and Family incertae sedis
Tricuspes E. von HUENE, 1933
Tricuspes cf. tubingensis

Referred material:
AIII-351 (NC 23), crown lacking root(s).

Description: One isolated tooth in the col-
lection from Hallau closely resembles the type of
Tricuspes tubingensis, but is slightly larger: crown
length = 2.82 mm, crown width = 1.47 mm. Like
the type, the central cusp is by far the largest and the
three main cusps are not directly aligned one behind
the other. Comparsion of occlusal views (Pl. 1:2a
& 1:5a illustrates the more bulbous outline of the
Hallau specimen and the absence of a cusp near the
base of the presumed posterolabial side of the princi-
pal cusp. On the anterior base of the anterior acces-
sory cusp, at the level of the maximum length of the
crown, is a minute but distinct conule.

The apex of the anterior accessory cusp was lost by
breakage, the apices of the other two main cusps ap-
pear to have been blunted by wear. No other wear
facets can be unequivocally identified. Comparison
of the lateral views of the two fossils (Pl. 1:2b—c &
1:5 b—c) suggests the crown of the tooth from Hallau
has a slightly more prominent basal constriction.
Particularly on the lingual side of the tooth, what
remains of its root shows a deep indentation indicative
of at least the beginnings of subdivision.

Discussion: Reference of AIII-351 from
Hallau to Tricuspes is based on similarities to the type
in size and gross morphology; there are no unique,
shared derived characters indicative of special phylo-
genetic relationship. Features distinguishing the two
teeth would easily fall within the range of dental
variation of a polyphyodont, advanced mammal-like
reptile or of the diphyodont or monophyodont cheek
teeth of an early mammal. Tentative allocation of
Tricuspes to the Mammalia is also made on incon-
clusive evidence. The complexity of the morphology
of thecrown, particularly the slight angulation in
alignment of the main cusps, and evidence suggesting
the crown was supported by a partially divided root
suggest, but do not demonstrate, mammalian affini-

ty.

Family Haramiyidae

To date all fragmentary teeth of haramıyids found
in the Tübingen-Stuttgart area that preserve enough
of the crown to warrant identification at the generic
level are referable to Thomasia with some degree of
certainty. None show characters diagnostic of Hara-
miya. In contrast the larger sample from Hallau
includes some teeth referable to Thomasia and Hara-
miya as well as a large collection of fragments that
can only be identified as haramiyid. Again it should
be stressed that as used here, Haramiya and Thomasia
are names for different types of teeth that are as-
sumed, primarily for the sake of convenience of des-
cription, to represent biological taxa. The conven-
tions for orientation and terminology employed are
those proposed by Hann (1973).

Thomasia PocHe, 1908
cf. Thomasia antiqua (PLIENINGER, 1847)

Referred material:

AIII-371 (NC 43), anterior end of Row B.

ATII-372 (NC 44), anterior end of RowB.

AIII-377 (NC 49), anterior end of RowB.

ATII-436 (NC 106), anterior end of RowB.

Revised diagnosis of Thomasia antiqua: Following
Sımpson (1928, p. 63—64), but recast in the terminol-
ogy of Hann (1973):

The posterior cusp of Row A is small but distinct
(minute to indistinct in T. anglica). Anterior cusp
of Row B preceded by a well marked basal cuspule
(a slight anterior cingulum not forming a distinct
cusp in T. anglica). Anterior cusp of Row B follow-
ed by three well-differentiated, small cusps and
then by a fourth, which is obscurely bifid (in 7. an-
glica followed by 4 to 6 cusps, the last of which are
posteromedial).

Description: The referred specimens include
one or more cusps posterior to the largest cusp of
Row B, but in none is the entire row preserved. Of
the three AIII-371 is the most inclusive preserving
what appears to be most of the basin-like depression
anterior to the saddle, as well as the two cusps on
either side of the largest cusp of Row B, which are of
approximately the same size. Only part of the basin
anterior to the saddle is preserved in AIII-372 and
the cusp anterior to the largest cusp of Row B is
distinctly smaller than that immediately behind this
cusp. AIII-377 is smaller but otherwise very similar
to this tooth.

AIII-436 requires special notice. It differs from the
specimens just described in the smaller difference in
size between the largest cusp of Row B and the two
immediately adjacent to it. Discrete, in echelon wear

facets are present on the lateral sides of the largest
cusp of Row B and the cusp behind it. These facets
are not in the same plane so could not have been pro-
duced by propalinal wear.

Discussion: Designation of these four speci-
mens as cf. Thomasia antiqua rests solely on the basis
that this is the only one of the four recognized hara-
miyid “species” in which a basal cuspule is thought to
constantly occur anterior to the highest cusp of
Row. B. A cusp in this position is usually not devel-
oped on teeth allocated to the other three “species”.
However, note that on AIII-309+314, described
below and designated Haramiya sp., the anterior
cingulum has a cusp-like terminus in front of Row B.
The projection is admittedly much smaller than the
cusps on the four specimens referred to cf. Thomasia
antiqua. Also PArrınGToN (1947, p. 712—713) noted
that a small cusp was present anterior to the largest
cusp of Row B on the lectoholotype of Haramiya
moorei (M211), but apparently is not a constant
feature of the crowns of the other eight teeth referred
to this species by Sımrson (1928). The difficulty in
taxonomic assignment of these four specimens from
Hallau not only reflects their fragmentary condition
but also stems from the typological nature of the
named taxa of haramiyids. It underscores our lack of
understanding of even the basic morphology and
ranges of variation of haramiyid dentitions.

Thomasia anglica Sımpson, 1928

Referred material:
AIII-295 (XLI, Taf. 1), anterior end of crown.

Description: AIII-295 (Pryer, 1956, Taf. 1,
Fig. 41) appears to be the anterior end of the crown of
a haramiyid molariform. The largest cusps of both
rows are at the preserved end of the crown, those
posterior to them are of lesser height. The highest
cusp is taken to be the anterior cusp of Row A. It
and the second cusp of Row A are larger and more
widely spaced than their counterparts inRow B. Low
but distinct, irregular ridges are present on the medial
sides of the cusps of Row A and the posterior sides of
cusps of Row B.

Anterior to the largest cusp of Row B is a narrow
cingular ledge that is abruptly terminated laterally
producing a small conule. This cingulum continues
across the crown onto the anterior slope of the first
cusp of Row A where there is a cusp-like irregularity
in the crest. Unfortunately the posterior end of the
crown of this tooth is missing and the number of cusps
in the two rows cannot be determined.
width of the crown is 1.72 mm.

Maximum

Discussion: Reference of this tooth to 7ho-
masia is based on the distinctly smaller size of the

second cusp in Row A relative to the first. Allocation
to T. anglica recognizes the absence of a distinct basal
or cingular cusp at the anterior end of Row B.
In Peyer’s (1956, Taf. 1) Figure 41 b of the anterior
end of the crown, the end of the anterior cingulum in
front of Row B is given an unwarranted cusp-like ap-
pearance. Figures 4la and 41c (ibid.) are more ac-
curate representations of its morphology. The other
two characters in the diagnosis of T. anglica require
knowledge of the total number of cusps in each row
and the morphology of the posterior end of the crown.
Neither can be determined because of damage to the
specimen. Thus, the reference of this tooth to a
“species” otherwise known only from England rests
solely on the absence of a distinct basal cusp anterior
to Row B. The presence or absence of such a cusp
could easily be a matter of individual variation.

The small, irregular ridges in the enamel on the
medial slopes of cusps of Row A and posterior slopes
of cusps of Row B of AIII-295 are a minor exception
to a criterion for distinguishing the teeth of hara-
miyids from those of multituberculates noted by
Hann (1973). Prior to this study ridges in the enamel
had not been observed on teeth of haramiyids.
Whether or not this occurrence should be interpreted
as the first indication of a derived character better
developed in members of the Multituberculata and
evidence of an ancestor-descendant relationship of
these groups remains to be determined.

?Thomasia sp.

Referred material:
ATII-308 (LIV, Taf. 2), posterior end of crown.

Discussion: AIII-308 (PEver, 1956, Taf. 2,
Fig. 54) is a fragment of the posterior end of a molari-
form possibly slightly smaller than AIII-295, which is
allocated to Thomasia anglica. Identification beyond
the level of haramiyid is based on the following
tenuous interpretations. As oriented in Figure 54a
(ibid.) the cusps of the upper (in the figure) row are
identified as part of Row A, which extends almost to
the posterior end of the crown. If this identification
is correct, the posterior cusp of Row A appears to
have been much smaller than the middle cusp, a char-
acteristic distinguishing Thomasia from Haramiya.

cf. Thomasia sp.

Referred material:
AIII-323 (LXIX, Taf. 12), posterior end of crown.

Description: Probably AIII-323 (PEyer,
1956, Taf. 12, Fig. 69) consists of at least half of the
posterior end of the crown of a molariform. A row of
one complete and half of another cusp (to the left in

Fig. 69, ibid.) appears to be what remains of Row A.
Row B is represented by four cusps of approximately
the same basal diameter and individual height but
increasing anteriorly in elevation on the crown. At
the preserved end of the crown a small basal cusp is
present on the slope of the terminal cusp of Row A.
It is linked to a small central cusp and that to the
terminal cusp of Row B by low crests. Maximum
width of the preserved part of the crown, measured
perpendicular to the central basin is 2.12 mm.

Discussion: The absence of a low crest or
higher saddle directly linking the terminal cusps of
the two rows, the consequent absence of any indica-
tion of an anterior cingulum or basin and, in occlusal
view, the sinuous outline of the crown all support
PEYER’s view that the fragment preserves the posterior
end of the crown. Comparison of the specimen to
Thomasia is suggested because of the apparent
decrease in size of the last two cusps in Row A and
closure of the central basin by two small cusps.

The tooth is large for a haramiyid molariform and
its sides are not parallel. On the outside of Row A
the crown had prominent lateral bulges around the
slopes of the last two cusps. In contrast, on the
outside slope of Row B there is a noticeable bulge
around the base of only one cusp. This irregularity in
occlusal outline broadly resembles that of the type of
Haramiya fissurae, but on detailed comparison many
differences become apparent.

Haramiya Sımpson, 1947

Teeth allocated to this genus differ from those of
Thomasia in the following respects (a formal diagnosis
is given by Sımrson, 1928, p. 55): The three cusps of
Row A are of approximately equal size or the
presumed anterior cusp is smaller than the other two.
Row B consists of a single, large anterior cusp fol-
lowed by three or four progressively smaller cusps.

Haramiya moorei (R. Owen, 1871)

Referred material:

ATIII-269 (XV, Taf. 1), anterior end of crown.
AIII-309+314 (LV & LX, Taf. 1, Fig. 3), crown
of molariform.

Two. fragments of a haramiyid molariform were
described separately by PEver (1956): AIII-314 (ibid.,
Taf. 1, Fig. 60) is the anterior end, AIII-309 (ibid.,
Taf. 1, Fig. 55) is the posterior end. The fragments
are now glued together and form the most complete
haramiyid tooth in the Hallau sample.

Description: Row A of AIII-309+314 con-
sists of three cusps of approximately equal height; the
anterior is only slightly lower in height than the other

lo 0

Figure 3: Outline drawing of AIII-309+314, Haramiya

moorei, Hallau local fauna, Switzerland. Regularly dotted

line marks the trace of the fracture. A. occlusal view,
B. lateral view. Scale equals 1 mm.

two. This row of cusps is not fully aligned, the apex
of the middle cusp is slightly lateral to those of the
terminal cusps (Fig. 3). In occlusal view the edge of
the crown lateral to Row A is bowed outward. Below
and posterior to the anterior cusp of Row A is a
distinct expansion of the crown forming an almost
cusp-like basal cingulum (note PEvYEr, 1956, Taf. 1,
Figs. 60a & 60c). Row B consists of four cusps of
which the first is distinctly higher and larger than the
other three. The lateral side of Row B is expanded
and bulbous except for the groove separating the third
and fourth cusps, which is deep and forms a cup-like
depression.

The central valley is straight from the relatively
low saddle linking the anterior cusps of Rows A and
B to the “U-shaped rim”. Anterior to the saddle is
a small basin limited anteriorly and laterally by
crests but extending without interruption to the edge
of the crown (ibid., Fig. 60a). In front of Row B the
crest iseexpanded but a distinct cusp does not appear to
have been present. The anterior basin appears to be
larger and better defined, at least laterally, than that

of the molar of H. moorei illustrated by Sımpson
(1928, Fig. 14), but the morphology of this area of the
crown differs among the teeth in Sımpson’s hypodigm
(ibid., p. 58). At the posterior end of the crown a
crest extends from the base of the last cusp of Row A
posteriorly then medially to meet the base of the last
cusp of Row B. At the posterior end of Row A the
side of the crown has lost some chips of enamel, but
clear evidence of a small basal cusp posterior to the
last cusp of Row A (PEyer, 1956, Taf. 1, Fig. 55a) is
present.

In occlusal view the tooth has an irregularly rec-
tangular outline (Fig. 3). Crown dimensions are as
follows: length = 2.23mm, maximum width of
crown across anterior cusps of Rows A and B =
1.83 mm, width at posterior end of Row A =
1.58 mm. The crown was supported by two trans-
versely expanded roots. Just below the crown the
broken surfaces of the roots have figure-eight outlines
suggesting that at a greater distance from the crown
both would have bifurcated.

Discussion: The relative proportions of the
cusps of both Rows A and B clearly justify reference
of AIII-309+314 to Haramiya. Morphologically the
specimen appears to be easily encompassed within the
range of variation of H. moorei.

Bases for reference of AIII-269 (PEyer, 1956,
Taf. 1, Fig. 15) to H. moorei are very tenuous. If the
complete cusp and the partial cusp shown above and
to the right in Peyer’s Figure 15a (ibid.) are taken
to be cusps of Row A and the other partial cusp
identified as the first cusp of Row B, comparison of
AIII-269 to the slightly smaller AIII-309+314
reveals some similarities. The first cusps of the two
rows are linked by a saddle that is only slightly higher
than the saddle of AIII-309+314. On AIII-269,
anterior to the first cusp of Row A, what is preserved
of a small basal cingulum could be part of the margin
of an anterior basin. Resembling AIII-309+314
lateral to the presumed cusps of Row A are several
small basal cusp-like expansions.

Haramiyid ?gen. et sp.

Referred material:

AIII-307 (LIII, Taf. 2), fragment of crown with

Row A.

AIII-370 (NC 42, Fig. 4), fragment of crown with
Row B.

Description: AIII-307 (Perer, 1956, Taf. 2,
Fig. 53) has been damaged since it was illustrated. It
appears to have consisted of an entire Row A of a
small molariform, crown length = 1.3 mm (measure-
ment from figure). The three cusps of Row ?A were
not well separated and of strikingly similar size and

height. One cusp of Row ?B appears to have been
preserved. It is illustrated as being linked to a termi-
nal cusp of Row ?A by a low crest, possibly the
anterior saddle.

AIII-370 consists of one row of cusps of another
small haramiyid molar (Fig. 4), crown length =

Tee

Figure 4: Outline drawing of AIII-370, haramiyid ?gen. et
sp., Hallau local fauna, Switzerland. A. occlusal view,
B. lateral view. Scale equals 1 mm.

1.98 mm. Apparently it was part of a relatively wide
tooth. The maximum width of the fragment meas-
ured from the midline of the central valley to the edge
of the crown is approximately 0.8 mm. One terminal
cusp is decidedly higher than the other three cusps sug-
gesting Row B is preserved. A saddle linking the
anterior cusps of Rows A and B, if present, must have
been small. A small fragment of a shelf-like cingulum
suggests the anterior basin was also small.

Discussion: These two fragments are parts
of relatively small haramiyid molariforms. If
AIII-307 is correctly identified as preserving Row A,
the cusps show the morphology characteristic of Hara-
miya, but the tooth was smaller than the smallest
molariform referred to H. moorei by Sımpson (1928;
M217, crown length = 1.7 mm). If AIII-370 preser-
ves Row B it preserves no characters allowing a choice
in allocation to either Thomasia or Haramiya. 'The
two specimens are grouped here simply to recognize
their similar, relatively small size.

Other fossils possibly representing haramiyids: For
the sake of completeness the following, slightly an-

notated list of fragments of haramiyid or haramiyid-

like molariforms is included:
AIII-256 (II, Taf. 12), several cusps. PEYER (1956,
p- 9) thought this was not a fragment of a mamma-
lian or mammal-like reptile tooth. The cusps
resemble those of some haramiyid or morganuco-
dontid teeth. The morphology of the base of the
crown is now obscured by glue.
AIII-257 (III, Taf. 12), a cusp. Possibly this is part
of a large haramiyid molariform.
AIII-285 (XXXI, Taf. 7), possibly a side of a
haramiyid molariform.
AIII-299 (XLV, Taf. 2), two small cusps, probably
haramiyid.
AIII-306 (LII, Taf. 2), a large cusp and parts of
two others that might be a fragment of a large
haramiyid molariform.
ATII-315 (LXI, Taf. 2), a row of two complete and
two fragments of cusps, possibly the posterior end
of Row B of a tooth the size of AIII-309+314,
Haramiya moorei.
AIII-374 (NC 46), part of a row of large cusps
from a haramiyid molariform.
AIII-388 (NC 58), one and a half cusps, possibly
haramiyid.
AIII-417 (NC 87), one and a half cusps, possibly
haramiyid.
AIII-429 (NC 99), a large cusp, possibly haramiyid.
ATII-461 (NC 131), heavily abraided crown of a
haramiyid molariform. Probably the posterior end
is preserved. The root is transversely broad and has
a figure-eight cross section.
AIII-491 (NC 161) probably preserves part of
Row B. The cusps are large, inflated, closely ap-
proximated, and separted by deep, narrow clefts.
The longitudinal crest connecting the apices of the
cusps is sharp and forms carnassial notches where it
passes from one cusp to another.

Isolated teeth that might include incisors or canines
of haramiyids are noted below in the section on Hel-
vetiodon schutzi, sp. et gen. nov.

Class Mammalia
Order Triconodonta
Family Morganucodontidae

The taxonomy and nomenclature of the Morganu-
codontidae has been reviewed elsewhere (CLEmEns,
1979). The conclusions of this review are that the
known morganucodontids can be allocated to four
genera of which the following three are monotypic:
Eozostrodon parvus from Somerset, England, and
Erythrotherium parringtoni and Megazostrodon
rudnerae from Lesotho. Morganucodon includes
three named species: M. watsoni, the common but pos-

sibly not the only species represented in the fissure
fillings in Wales, Great Britain, and M. oehleri and
M. heikuopengensis from China. A molariform of a
morganucodontid from the Bathonian (mid- Jurassic)
Forest Marble of England was illustrated by FREEMAN
(1976, Fig. 1 g) and later allocated to a new genus and
species, Wareolestes rex (Freeman, 1979).

Among the vertebrates in the Hallau local fauna
currently only the morganucodontids and morganuco-
dontid-like species can be classified as members of the
Mammalia with reasonable confidence. For the most
part this is not based upon the evidence provided by
the fossils from Hallau, but on the close resemblances
of these isolated teeth to those of morganucodontids
from other areas that are known from much more
complete material.

Morganucodon Kühne, 1949
Morganucodon peyeri, sp. nov.

Etymology: Dedicated to the late Prof. Bern-
hard PEyer.

Type specimen: AIII-329 (NC 1, Pl. 2:1),
slightly damaged, probably left, lower molariform
preserved in a fragment of dentary.

Type locality: Hallau bonebed, Kanton

Schaffhausen, Switzerland.

Diagnosis: A small morganucodontid with
molariform teeth smaller than those of Morganucodon
oehleri but approximately the same size as those of
M. watsoni, however, their crowns appear to be rela-
tively narrower than those of the latter species. Buc-
cal and lingual cingula of upper molariforms tend to
be more weakly developed than those of M. watsoni
and M. oehleri and the buccal more frequently inter-
rupted across the base of the principal cusp. Resem-
bling M. watsoni, but not M. oehleri, the lingual cin-
gulum of the lower molars of M. peyeri is relatively
well developed. Possibly the presence of a large,
anterolingual cingular cusp, almost as large as the
anterior accessory cusp, might separate M. peyeri
from the other species. No evidence of buccal cingu-
la, present on a very few lower molars of M. watsoni
(PARRINGTON, 1971) and on some of the few described
molars of M. oehleri (Mırıs, 1971), has been found in
the small sample of M. peyeri.

Referred material:
Upper molariform teeth

ATII-255 (I, Taf. 3), principal and posterior acces-
sory cusp, left.

AIII-264 (X, Taf. 4), anterior accessory cusp, left.
AIII-267 (XIII, Taf. 4), posterior accessory cusp
and part of principal cusp, right.

AIII-279 (XXV, Taf. 4), fragment of last molari-

form, left.

AIII-283 (XXIX, Taf. 4), posterior accessory cusp,

left.

AIII-292 (XXXVIII, Taf. 4), anterior accessory

cusp, right.

AIII-310 (LVI, Taf. 3), principal and posterior ac-

cessory cusp in fragment of maxilla, left.

AIII-324 (LXX, Taf. 12), principal and posterior
. accessory cusp, left.

AIII-428 (NC 98), posterior accessory cusp?

Lower molariform teeth

AIII-266 (XII, Taf. 4), principal cusp and kühne-
cone, left.

AIII-273 (XIX, Taf. 4), posterior accessory cusp
and kühnecone, right.

AIII-280 (XXVI, Taf. 4), fragment with kühne-
cone, left.

AIII-284 (XXX, Taf. 4), possibly fragment of
anterior end of crown, right.

AIII-296 (XLII, Taf. 4), anterior accessory cusp,
right.

AIII-319 (LXV, Taf. 5), principal cusp, kühnecone,
and posterior accessory cusp, left.

AIII-380 (NC 50), principal cusp, kühnecone, and
posterior accessory cusp, left.

AIII-480 (NC 150), anterior accessory cusp and
part of principal cusp, left.

Premolariforms

AIII-258 (IV, Taf. 6), posterior lower premolari-
form, left.

AIII-261 (VII, Taf. 2), posterior lower premolari-
form, left.

AIII-263 (IX, Taf. 6), upper premolariform, right.
AIII-277 (XXIII, Taf. 6), premolariform.

AIII-278 (XXIV, Taf. 6), premolariform.

AIII-282 (XX VIII, Taf. 6), premolariform.
AIII-335 (NC 7), posterior lower premolariform,
left.

AIII-336 (NC 8), upper premolariform, left.
AIII-350 (NC 22), premolariform.

AIII-368 (NC 40), upper premolariform, left.
AIII-423 (NC 93), premolariform.

ATIII-441 (NC 111), premolariform.

AIII-460 (NC 130), upper premolariform.
AIII-509, upper premolariform.

Upper molariforms: The available sample
from Hallau lacks examples of complete upper molari-
form teeth, and the problems of identification and
orientation of the fossils are challenging. Criteria
developed for orientation of isolated teeth of Morgan-
ucodon watsoni (see, for example, Mırıs, 1971) stem
from studies of teeth found in maxillary fragments,
but unfortunately do not always go into the detail

necessary for analysis of isolated teeth. In the follow-
ing paragraphs the criteria for orientation of the
upper molariform teeth are evaluated in a description
of the dental morphology. The position in the denti-
tion and orientation of many of the fragments pro-
posed here (see list of referred specimens) differ from
those suggested by P£ver (1956). Although usually in
agreement on identification of specimens as upper and
lower molariforms and on determination of their
bucco-lingual orientation, we frequently differ on
identification of the anterior and posterior ends of the
crowns.

Resembling M. watsoni, teeth identified as upper
molars of M. peyeri have three main cusps aligned
mesiodistally with the principal (central) cusp larger
and higher than either the anterior or posterior acces-
sory cusp. Differences in their height are not as great
as those distinguishing the main cusps of the lower
molars. A second criterion applied in identification
of upper molars is the presence of both buccal and
Mırıs (1971, p. 37) noted,
“although the cingulum is continuous around the
unworn tooth [upper molars of M. watsoni], it
rapidly wears away on the lingual side”. Upper
molars of Erythrotherinm and Megazostrodon are
also characterized by the presence of both cingula but
they show greater variation in development. A cen-
tral break or gap interrupts the buccal cingula of
M!-? of Megazostrodon and M! of Erythrotherium.
Fragments of molariform teeth allocated to M. peyeri
with both buccal and lingual cingula (structures more
extensive than simply cusps on the sides of the
anterior and posterior ends of the crown) have been
identified as upper molariforms. Apparently unlike
M. watsoni, but similar to Megazostrodon and Ery-
throtherium, the buccal, and less frequently lingual
cingula of unworn upper molariforms of M. peyeri
are not always continuous along the total length of
the crown. In the few instances where the principal
and one accessory cusp are preserved and their relative
size and height can be determined, the teeth having the
cusp proportions taken as characteristic of upper
molariforms always have both lingual and buccal
cingula.

lingual basal cingula.

ParrınGToN (1973, 1978) noted another criterion for
differentiating upper from lower molars of M. watso-
ni; this is a feature of the morphology of their roots.
The anterior root of an upper molar of M. watsoni
tends to be oval in cross section with its long axis
oriented anteroposteriorly while the posterior root
has the long axis of its oval cross section oriented
transversely. The long axes of cross sections of both
roots of lower molars are oriented anteroposteriorly.
This criterion does not appear to be fully applicable to
upper molariforms of M. peyeri. On some (e. g.,
AIII-310) the posterior root, identified on criteria of

crown morphology, is transversely expanded, but on
others (e. g., AIII-283 and the posterior root of the
tooth preceding the molar preserved in AIII-310
[Peyer, 1956, Taf. 3, Fig. 56e]) it is not. These
dissimilarities might reflect differences in ontogenetic
stage, transverse expansions being a characteristic of
older animals; position in the dentition; or perhaps
the expansion is a derived morphology that did not
characterize all members of M. peyeri.

On the basis of the morphology of AIII-310 (PEyeEr,
1956, Taf. 3, Fig. 56), the only fragment of an upper
molariform preserved in a bit of the maxillary bone
and, where applicable, comparisons with M. watsoni,
Erythrotherium, and Megazostrodon, several criteria
appear to be available for distinguishing the buccal
and lingual sides of the crown. First, the buccal cin-
gulum is usually wider than the lingual and surmount-
ed by more and larger cusps. The degree of difference
in these features, if any, varies between teeth. MırLs
(1971) noted that in M. watsoni development of the
buccal cingulum varies along the tooth row being pro-
portionately widest on the anterior molars. The few
available fossils of M. peyeri suggest its buccal cin-
gulum is more frequently interrupted across the slope
of the principal cusp than the lingual.

Secondly, when viewed in transverse section, the
apices of the principal and accessory cusps are not
situated over the midpoint of the crown but are dis-
placed lingually. Likewise the lingual slope of these
cusps rises more steeply and is less convex than the
buccal. Particularly on the slopes of the principal
cusp, the labial cingulum is situated higher (nearer the
apex of the cusp) than the buccal.

Finally, the general occlusal pattern of therapsids
and mammals suggests that wear facets might be
found on the lingual side of the upper molars, pro-
duced by contact with the labial sides of the lowers.
Unfortunately, there is clear evidence that the bones
concentrated in the Hallau bonebed underwent con-
siderable post-mortem abrasion. Although some teeth
show apical facets on the cusps that were most likely
formed by abrasion with food, I have not been able to
unequivocally identify wear facets on sides of any
molariform upper teeth. The only possible exceptions
are AIII-267 (PEyEr, 1956, Taf. 4, Fig. 13) where one
side of the crown is heavily abraided, and possibly
ATII-310 (ibid., Taf. 3, Fig. 56), where cusps of the
lingual cingulum might be blunted by wear.

Criteria utilized for identification of the anterior
and posterior ends of the crown are even more uncer-
tain for the fragment of maxillary preserved with
AIII-310 does not give any information about its
anteroposterior orientation. Usually in cheek teeth of
early mammals the anterior edges of the main cusps do
not rise as steeply, are more convex, and are longer
than the posterior. This criterion usually appears to

be applicable to at least the principal and anterior
accessory cusps.

Mırıs (1971) noted that the anterior accessory cusp
is lower than the posterior on M!-2, almost equal on
M3, and quite equal on M* and presumed M5 of
M. watsoni. Unfortunately none of the fragments of
teeth from Hallau preserve both accessory cusps.
However the relative depths of the notches separating
the main and accessory cusps can be determined. Like
upper molars of Morganucodon watsoni the notch
separating the anterior accessory cusp from the prin-
cipal cusp appears to have been slightly deeper than
that separating the principal and posterior accessory
cusp.

In triconodontids the cheek teeth are interlocked by
a projecting cusp on the posterior end of one tooth
and a groove or basin, usually bounded by buccal and
lingual cusps, on the anterior end of the following
tooth. This mechanism is weakly developed in
M. watsoni (Mırıs, 1971) where the anterior end of a
molariform can slightly overlap the buccal side of the
preceding tooth. On some upper molariforms of
M. peyeri (e. g., AIII-310) the end of the crown with
a projecting cingular cusp is supported by a trans-
versely wide root; in others (e. g., AIII-283) the root
at this end of the crown is elongated in an anteropos-
terior direction.

In his attempts to distinguish the anterior and pos-
terior ends of the crown PEYErR (1956) considered the
position of the edge of the crown relative to the
underlying root. He thought that characteristically
the “anterior” end of the crown juts forward,
balcony-like, in advance of the “anterior” face of the
root, while the “posterior” accessory cusp is more
directly situated over the “posterior” root and the back
of the crown is almost in line with the back of the root.
On the basis of the other criteria adopted here some of
the anteroposterior orientations proposed by PEYER
must be reversed and the balcony-like projections of the
crowns of some teeth (e. g., AIII-255) are considered
to be at the posterior end of the crown. However, the
projections of the crown on what are thought to be
posterior ends of other teeth are not as extreme and
match those of fragments of the anterior end of the
crown (e. g., AIII-292). As is the case with orienta-
tion of the maximum diameter of the root, the rela-
tionship of the margins of the root to the crown in
M. peyeri might be diagnostic in some instances, but
the morphology of the roots could be more variable
than morphology of the cusps, and might require
information on ontogenetic stage of the tooth before
being applied.

In summary, most of the smaller fragments appear
to pertain to molariform teeth similar to AIII-255
and AIII-310. A composite upper molariform can be
briefly characterized as being dominated by three

main cusps, of which the principal is higher than either
the anterior or posterior accessory cusps. Probably on
any tooth the posterior accessory cusp is as large as, if
not larger than, the anterior and separated from the
principal cusp by a shallower notch. The apices of
these cusps are displaced toward the lingual side of the
crown. Cusp development on the broad buccal cin-
gulum varies, but usually the cusps are larger and
more numerous than those on the narrower lingual
cingulum. Apparently, the larger buccal cingular
cusps are situated on the posterior part of the cingu-
lum. When viewed in a transverse section, the lingual
cingulum is higher (closer to the apices of the main
cusps) than the buccal and the lingual slopes of the
cusps are steeper than the buccal. At the posterior
end of the crown a cingular cusp projects distally to
form a weak interlocking mechanism with the depres-
sion in the anterior end of the next (posterior) molari-
form tooth. Two well separated, slightly diverging
roots support the crown. In at least a few specimens
the anterior root is anteroposteriorly elongated while
the posterior is transversely widened.

One fragmentary tooth differs from this generalized
pattern. AIII-279 (PEyer, 1956, Taf. 4, Fig. 25) is
heavily damaged and beyond the presence of a large
central cusp and anterior and posterior accessory
cusps, little can be said about the morphology of its
crown. However, the crown appears to have been
supported by two closely approximated roots. As
Pever (1956, p. 26—27) suggested, what remains of
the tooth is not unlike the posterior upper molars of
triconodonts and, in a general way, resembles last up-
per molariform teeth of M. watsoni.

Lower molariforms: A fossil consisting of
a damaged molariform and fragment of a mandible
(AIII-329, Pl. 2:1) is the most complete mammalian
specimen in the collections made by Prof. PEyEr after
he prepared his 1956 monograph and has been chosen
as the type specimen of Morganucodon peyeri. This
and AIII-319 (Pever, 1956, Taf. 5, Fig. 65), a frag-
ment consisting of the principal cusp and posterior end
of the crown, are the basis for reconstructing the mor-
phology of the lower molariform teeth. Fortunately
the bone associated with AIII-329 is clearly a frag-
ment of dentary and both these molariforms preserve
the kühnecone, which identifies both the lingual and
posterior sides of the crown. Unlike upper molari-
forms referred to M. peyeri, there appears to be little
question concerning the anteroposterior and lateral
orientation of the lowers.

Resembling the upper molariform teeth, the crown
of the lowers consists of three main cusps essentially
aligned anteroposteriorly with the principal (central)
cusp distinctly larger and higher than the anterior and
posterior accessory cusps. Of the two accessory cusps
the posterior is the larger. In one fragment (AIll-

380) the notch separating the principal and posterior
accessory cusps ends in a deep cleft similar to the car-
nassial notch of therian carnivores. AIII-319 demon-
strates the presence of a posterior cingular cusp behind
and in line with the posterior accessory cusp; AIII-
329 (Pl. 2:1) is damaged in this region but almost
certainly had a distinct posterior cingular cusp. The
posterior cingular cusp of AIII-273 (PEver, 1956,
Taf. 4, Fig. 19) is slightly more prominent than that of
AIII-319.

The buccal side of the crown lacks any indication of
basal cusps or cingula. In contrast, on the anterolin-
gual side of the crown there are two cusps on AIII-
329. The anterior is the larger of the two and is
situated beside but slightly in advance of the only
somewhat larger anterior accessory cusp. In occlusal
view the anterolingual cingular cusp and anterior ac-
cessory cusp bound a shallow concavity in the anterior
end of the crown, which probably received the poste-
rior cingular cusp of the preceding molar. If correctly
referred to M. peyeri, AIII-296 (PEver, 1956, Taf. 4,
Fig. 42) demonstrates the development of an inter-
dentinal wear facet on the front of the crown below
and between the anterolingual cingular cusp and an-
terior accessory cusp.

On both AIII-319 and AIII-329 part of the lingual
slope of the principal cusp extends to the base of the
crown without interruption by a cingulum. The
kühnecone of AIII-329 is relatively larger than that
of AIII-319, but both are distinct cusps separated by
a cleft from the posterolingual side of the principal
cusp.

Behind the kühnecone of AIII-319 are four cingular
cusps generally increasing in height and size posterior-
ly. The most posterior of these lies lingual to the
largest posterior cingular cusp, which is situated
behind the posterior accessory cusp. The area of the
crown between the kühnecone and the posterior cin-
gular cusp shows considerable variation in the
development of small cingular cusps. AIII-319 has a
high number of cusps while, at the other extreme, on
AIII-380, although a cingulum links the kühnecone
with the posterior cingular cusp, no individual cusps
are present between them.

The crown is supported by two roots but AIII-319
and AIII-329 give little information concerning their
morphology. Pever (1956) identified AIII-280 (ibid.,
Taf. 4, Fig. 26) as a last upper molariform but more
likely it is a fragment of a lower molariform. His
figures of the root of this specimen show the suggestion
of a blunderbuss-like expansion of the tip of the root.

As was the case with the upper molars, the only
unambiguous traces of dental wear are facets on the
apices of some cusps (e. g., AIII-266, PEYER, 1956,
Taf. 4, Fig. 12). The fragment of dentary of AIII-
329 is heavily damaged. A groove along its ventro-

lingual edge might be what remains of a trough for
accessory mandibular bones or, with equal uncertain-
ty, it might be simply an artifact of postdepositional
crushing.

Dimensions of molariforms: An ac-
curate assessment of the size of the upper molariforms
cannot be made on the basis of the present sample
because of the lack of complete teeth. Several speci-
mens are made up of the principal cusp, one accessory
cusp, and, infrequently, part of the base of the missing
accessory cusp. The range of variation in length of
the preserved parts of their crowns is from approxi-
mately 1.2 to 1.5 mm. The longest fragment of crown
is that of AIII-310, which is the least damaged tooth.
Probably it had a maximum crown length of approx-
imately 1.6 to 1.7 mm.

Width of the crown of the upper molars of
M. watsoni varies according to the relative develop-
ment of the buccal and lingual cingula and the amount
of wear on the lingual side of the crown. The same
sources of variation could influence measurements of
the width of molars of M. peyeri. In order to get an
approximation of average crown width of the upper
molariforms of the latter species, the maximum widths
of the fragments were measured with the following
results: N = 7, OR = .48—.70 mm, M = .58 mm.

Only slightly more data on the dimensions of the
lower molariforms of M. peyeri are available. The
perimeter of the crown of one lower molariform,
AIII-329, is intact and its dimensions are: length =
1.65 mm, width = .62 mm. Maximum widths of the
fragments of lower molariforms were measured with
the following results: N=6, OR = .59—.66 mm,
M = .64 mm.

While making comparisons of the fragmentary teeth
of M. peyeri with a small reference collection of teeth
of M. watsoni it appeared that the teeth of M. peyeri
were longer (anteroposteriorly) and relatively nar-
rower (transversely). With so little data available on
the dimensions of the teeth of M. peyeri it is, of course,
impossible to make any rigorous comparisons. Howev-
er, to see if there was any basis for this impression of
differences in proportions, a series of teeth of M. wat-
soni were measured. These teeth are all from Pont-
alun Quarry, Wales (see KErMAcK et al., 1973) and are
preserved in mandibles so that their position in the
dental arcade could be determined on criteria other
than the individual morphology of their crowns.
These specimens are in the collections of the British
Museum (Natural History); Department of Zoology,
University College London; and Museum of Zoology,
Cambridge University. My analysis was focused on
the question, to what extent, if any, do the teeth of the
species of Morganucodon represented at Hallau differ
in coronal dimensions from those of the sample of
M. watsoni recovered from Pontalun Quarry? It is

not a substitute for a still needed, thorough taxonomic
study of the species of Morganucodon represented in
the collections from Pontalun and other fossil locali-
ties in southern Wales.

As has been recognized by others (e. g., see Mııs,
1971, PARRINGTON, 1971) the longest molariform teeth
of M. watsoni are M? and M,. The data on the
dimensions of these teeth obtained from a study of the
Pontalun sample are given in Table 1. Their coeffi-
cients of variation are high. This could reflect taxono-
mic heterogeneity, the mechanical difficulties of ob-
taining precise measurements of such small teeth, or

both.
Table 1

Comparisons of dimensions of molariform teeth of
Morganucodon watsoni, Pontalun Quarry,
and M. peyeri, Hallau local fauna.

N OR M S CV
Morganucodon watsoni
M?
Length 167 1.10-1.617 71337 2157 107
Width 11 Ban 68 091355
M;
Length 147 1.17-1:65 1.43.13 94
Width 14 .59- .81 69.075101

Morganucodon peyeri

Lower molariform, AIII-329
Length 1.65
Width .62

Comparison of the dimensions of AIII-329 with the
data on M, of M. watsoni (Table 1) shows that its
crown is as long as the longest M, in this sample from
Pontalun, but its transverse width, 0.62 mm, is less
than the mean value. The mean breadths of the frag-
ments of molariforms of M. peyeri, 0.58 mm for the
upper and 0.64 mm for the lower, are smaller than the
means of M2, M3, M, and M,, but larger than means
of M! and M, of M. watsoni. However, the first
molariforms of M. watsoni are short (anteroposterior-
ly) with mean lengths of only 1.13 mm and 1.20 mm
respectively.

Visual comparisons of apparently homologous parts
of fragments of teeth of M. peyeri and M. watsoni
suggest the molariform teeth of M. peyeri tend to be
longer and relatively narrower than those of M. wat-
soni. When compared to a sample of M. watsoni
from Pontalun, Wales, the few dimensions that can be
obtained from the fossils from Hallau appear to sub-
stantiate this impression.

Premolariform teeth possibly referable to
Morganucodon peyeri: Considering the relative abun-

dance of its molariform teeth, most likely premolari-
form teeth of M. peyeri are included in the collection
from Hallau. The small premolariform teeth de-
scribed in this section are all of the simple, trenchant
morphology that would be expected in the dentition
of a morganucodontid. However, M. peyeri, is not
the only morganucodontid present in the sample from
Hallau and there are several other kinds of animals, be
they mammal-like reptiles or mammals, represented
that might also have had such simple, premolariforms
in their dentitions. Grouping the descriptions of these
teeth in this section is primarily a literary convenience
and only secondarily a suggestion of possible zoologi-
cal affinities.

AIII-258 (PEver, 1956, Taf. 6, Fig. 4), AIII-261
(ibid., Taf. 2, Fig. 7), and AIII-335: Assuming the
pattern of variation in length of the postcanines of
M. peyeri is similar to that of M. watsoni, these pre-
molariforms are of a size appropriate for posterior
lower premolariforms of M. peyeri (OR length =
1.15—1.25 mm). The principal cusp of each tooth has
a high trenchant crown suggesting it is part of the
lower dentition. Two of the three specimens had a
low anterior basal cusp. Basal cingula are lacking on
the buccal and lingual side of the crown. Two low
posterior cusps are present, one directly behind the
principal cusp, the other more posterior and lingual in
position. To this extent these premolariforms resem-
ble P,’sof M. watsoni, but the premolars of M. watsoni
usually (Mırıs, 1971) have two anterior basal cusps,
a short anterolingual cingulum, and a small kühne-
cone. No premolariforms resembling P,’s of M. wat-
soni in these details have yet been discovered at Hal-
lau. Whether the absence of additional anterior basal
cusps and a kühnecone on P, of M. peyeri is a cha-
racteristic of this species or whether the lower poste-
rior premolariform of M. peyeri has not been discov-
ered, of course, cannot yet be determined.

One of the premolariforms, AIII-258 (PEveEr, 1956,
Taf. 6, Fig. 4) lacks enamel on the buccal side of the
posterior accessory cusp. This might be the result of
occlusion with an upper tooth.

Five premolariform teeth, AIII-263 (PEver, 1956,
Taf.6, Fig. 9), AIII-336, AIII-368 (Pl. 2:2), AIII-
460, and AIII-509 could be upper premolariforms of
M. peyeri. Principal cusps of all these teeth are
relatively low in comparison to those of the group of
premolariforms just described. Similar differences in
proportions distinguish upper and lower premolars of
M. watsoni. Among these premolariforms from Hal-
lau there is variation in development of the basal cin-
gula from absence to presence of an almost complete
lingual and a posterior buccal cingulum (Pl. 2:2), a
range of variation like that found in M. watsoni. Di-
mensions of the crowns of these premolariforms are
as follows: OR length = 0.70—0.95 mm, OR

width = 0.44—0.55 mm. Major sections of the roots
of AIII-368 (Pl. 2:2) are preserved and show that the
posterior was slightly larger and transversely wider
than the anterior.

Other premolariforms exhibit some differences in
proportions but all have simple, trenchant crowns and
might also be referred to M. peyeri. Three, AIII-277
(Pever, 1956, Taf. 6, Fig. 23), AIII-278 (ibid., Taf. 6,
Fig. 24) and AIII-423 are of small size (OR length =
0.77—1.03 mm). Their crowns are simple consisting
of a principal cusp, a small posterior basal cusp and,
on one, an anterior basal cusp. The crowns of AIII-
277 and AIII-278 are supported by two, well sepa-
rated roots; the roots of AIII-423 are missing. Two
other small premolariforms, AIII-350 and AIII-441
(OR length = 0.82—1.00 mm) have similar crown
morphologies but the roots are not fully divided.
Finally, AIII-282 (PEver, 1956, Taf. 6, Fig. 28) is a
single-rooted premolariform with a large principal
cusp anda small posterior accessory cusp.

Discussion: The systematic relationships of
Morganucodon peyeri are considered in a later section
following the descriptions of the other morganuco-
dontid and morganucodontid-like mammals of the
Hallau local fauna.

?Morganucodon sp.

Referred material:

AIII-305 (LI, Taf. 7), fragment of upper molari-
form, left.
AIII-333 (NC 5, Pl. 2:3) fragment of upper molari-
form, left.
AIII-340 (NC 12, Pl. 2:4) fragment of lower molari-
form, left.

Description: These three teeth are approxi-
mately the same size as the molariforms of Morganu-
codon peyeri and resemble them in general configura-
tion. However, they are easily distinguished by the
absence or relatively weak development of buccal and
lingual cingula, and symmetry in length and curvature
of the anterior and posterior slopes of the main cusps.
Also, if the projecting cingular cusp is at the posterior
end of the crown then the posterior roots of these teeth
do not show the distinct transverse broadening typical
of posterior roots of the upper molars of M. watsoni
and some teeth from Hallau referred to M. peyeri
(e. g., AIII-255 and AIII-310).

Of the three, AIII-340 (Pl. 2:4) is the most com-
plete preserving most of the crown and part of one
root. Its smallest cusp is assumed to be at the poste-
rior end of the crown. This cusp is slightly offset in
what is taken to be a lingual direction from the line
of the three main cusps. The other end of the crown is

damaged and the presence of an anterior basal cusp
cannot be excluded. Except for a minor cingulum
bordering a basin between the posterior basal and
posterior accessory cusp, no other cingula are present
on the crown. This essential absence of cingula and
relative size of the cusps suggests AIII-340 is a lower
molariform. Other than apical blunting of the main
cusps there is no indication of wear facets. The crown
was supported by two, well separated roots. The
anterior root appears to have been longer anteropos-
teriorly than the posterior. The posterior probably
was slightly wider than the anterior, but the difference
might not have been great. A curious rugose area on
the presumed buccal side of the posterior root proba-
bly is a growth on the root and not a thickening of its
wall. A color change on the broken end of the root
appears to demark the “normal” wall of the root
from the exostosis. Dimensions of the crown of AIII-
340 are as follows: length = 1.54 mm, width =
0.48 mm.

The relatively smaller difference in height of their
main cusps and presence of basal cingula on one or
both sides of their crowns suggest AIII-305 (PEYER,
1956, Taf. 7, Fig. 51) and AIII-333 (NC 5, Pl. 2:3)
are upper molariforms. Neither specimen is complete.
Both have lost one accessory cusp, which on both teeth
teeth appears to have been the anterior. The degree
of cingular development on the two teeth differs but,
in transverse section, the apices of the main cusps of
both are set to one side of the midlines of the crowns.
Their steeper slopes are assumed to be on the lingual
side of the crown. If so oriented the buccal cingulum
of AIII-305 would be relatively better developed and
more continuous than the lingual. AIII-333 lacks a
lingual cingulum and the buccal is not continuous.
Both teeth were supported by two, well separated
roots. The widths of the crowns are as follows:
0.37 mm (AIII-333); 0.66 mm (AIII-305).

Discussion: Several interpretations of taxo-
nomic affinity of these teeth are immediately ap-
parent. First, they are teeth of a small morganuco-
dontid that retain a primitive condition in only
modest development of basal cingula. Or that the
simplicity of their crowns indicates they are posterior
premolariforms, deciduous premolariforms, or poste-
rior molariforms of Morganucodon peyeri. Finally,
and with equal uncertainty, it might be argued that
these teeth document the presence of an early repre-
sentative of the triconodontine triconodontids. Thus
designation of these teeth as ?Morganucodon sp. is no
more than a device to highlight their distinctive mor-
phology. It is recognized that most of the similarities
of these fossils to teeth of species of Morganucodon
probably are the result of shared plesiomorphous
characters.

Order ?Triconodonta
Family ?Morganucodontidae
Helvetiodon gen. nov.

Etymology: Helvetia, Switzerland; Odontos,
Greek, tooth.

Type species: Helvetiodon schutzi sp. nov.

Diagnosis: Asforthetype and only species.

Helvetiodon schutzi sp. nov.

Etymology: Named for Herr Emil ScHurz
of Neunkirch who assisted Prof. PEYER in his research
inthe Hallau area.

Type: AIII-348 (NC 20, Pl. 3:1), a damaged
molariform, tentatively identified as a right, upper
molariform.

Type locality: Hallau bonebed, Kanton
Schaffhausen, Switzerland.

Diagnosis: Based on isolated teeth thought to
be upper molariforms. Premolariforms probably are
present in the sample, but lower molariforms are
either missing or are unrecognized. Molariforms are
large, approximately one and a half times the size of
those of Morganucodon, Megazostrodon, and Ery-
throtherium, and in the size range of Tricuspes and
Wareolestes. They differ from molariforms of Tri-
cuspes in more complex morphology of the crown
with extensive development of labial and lingual
cingula and cusps. Presumed upper molariforms of
Helvetiodon differ from those of Megazostrodon in
absence of an anterior accessory cusp, more massive
and bulbous morphology, and different pattern of
development of cingular cusps. Wareolestes is known
from a tooth that in number and disposition of cusps
is little more than an enlarged edition of a lower
molar of Morganucodon. In contrast, the presumed
upper molariforms of Helvetiodon schutzi are not as
close in their morphological resemblance to the upper
molars of any known species of Morganucodon.

Referred materials:
Molariforms

AIII-268 (XIV, Taf. 4), fragment of posterior end
of upper molariform.

AIII-270 (XVI, Taf. 4), fragment of posterior end
of upper molariform.

AIII-303 (XLIX, Taf. 7), fragment of posterior end
of upper molariform.

AIII-354 (NC 26, Pl. 3:2), crushed crown lacking
posterior end, upper right.

AIII-390 (NC 60), fragment of posterior end of
upper molariform.

AIII-437 (NC 107), fragment of an end of a mola-
riform.

Premolariforms (reference to Helvetiodon
schutzi tentative, see text)

AIII-259 (V, Taf. 11), anterior premolariform or
incisiform.

AIII-265 (XI, Taf. 7), principal and anterior basal
cusp.

AIII-291 (XXXVII, Taf. 8), anterior premolari-
form.

ATII-302 (XLVIII, Taf. 7), principal and accessory
cusp.

AIII-325 (LXXT, Taf. 12), principal cusp.

ATII-334 (NC 6), principal and accessory cusp.
ATII-359 (NC 31), slightly damaged, principal and
accessory cusp.

AIII-360 (NC 32), fragment with principal and
accessory cusp.

ATII-393 (NC 63), fragment of crown.

ATII-402 (NC 72), principal and small, ?anterior
basal cusp.

ATII-424 (NC 94, Pl. 3:3), anterior premolar.
ATII-439 (NC 109), anterior premolar.

ATII-458 (NC 128, Pl. 3:4), principal and accessory
cusp.

AIII-459 (NC 129), principal and small, ?anterior
basal cusp.

Incisiforms and caniniforms (reference
to Helvetiodon schutzi tentative, see text).

AIII-260 (VI, Taf. 6)
AIII-271 (XVII, Taf. 6)
AIII-274 (XX, Taf. 8)
AIII-294 (XL, Taf. 6)
AIII-304 (L, Taf. 11)
AIII-311 (LVII, Taf. 11)
AIII-316 (LXII, Taf. 8)
AIII-326 (LXXII, Taf. 12)
AIII-330 (NC 2)
AIII-341 (NC 13)
AIII-345 (NC 17)
ATII-347 (NC 19)
AIII-349 (NC 21)
AIII-365 (NC 37)
AIII-416 (NC 86)
AIII-477 (NC 147)

The hypodigm of this taxon consists of two nearly
complete molariforms and several fragments. None
are of typical haramiyid morphology, and they show
some resemblance to teeth of morganucodontids. The
teeth are large, about one and a half times the size of
teeth of similar morphology referred to Morganuco-
don peyeri, and lie in the estimated size range of Tri-
cuspes tubingensis. A number of premolariforms
ranging from essentially complete teeth to fragments

of crowns, as well as incisiforms and caniniforms are
also described here. These are the large premolari-
forms, incisiforms, and caniniforms found at Hallau
and for the sake of convenience are described as a unit.
Some could well be elements of the dentition of Hel-
vetiodon, but the possibility that others are parts of
dentitions of Tricuspes, haramiyids, or other mammals
or mammal-like reptiles cannot be excluded.

Description: Both the type specimen of
Helvetiodon schutzi and the complete referred molari-
form (AIII-354) are elements of the new collection
assembled after 1956. "The two fossils preserve a large
part but not all ofthecrown. Asa result of abrasion
and/or chemical attack the type (AIII-348) has lost
large segments of its enamel cap (in Pl. 3:1 enamel-
covered areas are rendered in darker tones). More of
the crown of AIII-354 (Pl. 3:2) is preserved, but
the tooth has been crushed laterally (buccolingually)
and distorted. The crowns of both teeth are dominat-
ed by a large principal cusp. When viewed laterally,
the longer, slightly steeper slope of the principal cusp
is assumed to be its anterior slope, and the accessory
cusp a posterior accessory cusp.

In comparison to known morganucodontids and
triconodontids the relative height of the principal cusp
of these two teeth would be extreme but not inappro-
priate for an upper molariform (e. g., note the M? of
Morganucodon oehleri [MıLzs, 1971, Pl. 5A]) or the
last, upper premolariform (note M. watsoni [ibid.,
Pl. 1D; Parrıncron, 1971, Fig. 16f] or M. oehleri
[Mırıs, 1971, Pl. 5A]). However, the relative pro-
portions of height of principal cusp to length of crown
more frequently would be matched by lower molars
of Morganucodon. This characteristic suggesting the
two teeth are lower molariforms is contradicted by
the presence of both lingual and buccal cingula on the
type and, probably, the referred specimen. With few
exceptions (e. g., note Hallautherium gen. nov., de-
scribed below) development of basal cingula on both
sides of the crown is a definitive characteristic of upper
molariform teeth of advanced mammal-like reptiles
and early mammals. Provisionally, this character is
given greater weight. But it must be stressed that
both teeth are isolated and their tentative identifica-
tion as upper molariforms is not substantiated by as-
sociation with recognizable fragments of the maxil-
lary bone.

Finally, and again essentially arbitrarily, degrees of
completeness and complexity of the basal cingula are
used to distinguish buccal and lingual sides of the
In morganucodontids, if there is any dif-
ference in complexity or completeness of the basal
cingula of upper molars, usually the buccal cingulum is
not as completely developed as the lingual, but it can
be wider and carry larger cusps.

crown.

In summary, all the molariforms and fragments of
molariforms allocated to Helvetiodon schutzi are
isolated specimens lacking associated segments of
maxillary or dentary bones. Their identification as
elements of the upper dentition and determination of
anteroposterior as well as lateral orientations are
based primarily on comparison with molariform teeth
of morganucodontids, to which they show some
resemblance. All these determinations of position and
orientation must be regarded as tentative.

Posterior to the dominant, principal cusp of the
type (Pl. 3:1) is a small, low accessory cusp, which is
now missing most of its enamel cap. An anterior ac-
cessory cusp, similar to those found on molars of
Morganucodon was not present. The two major
cusps at the anterior end of the crown are set laterally;
the anterolingual is larger and positioned more anter-
iorly than the buccal. Configuration of the dentine
core of the anterobuccal cusp suggests a ridge con-
nected its apex with the crest along the anterior edge
of the principal cusp.

On the lingual side of the preserved part of the
crown the basal cingulum becomes lower from both
ends toward the midpoint where it is interrupted for a
short distance. The anterior segment carries two
small cusps behind the large anterior cusp. On the
posterior segment a large cingular cusp is present
lingual to the notch separating the principal and
posterior accessory cusps. What remains of the rest of
the posterior end of the crown has been stripped of
most of its enamel covering. There appears to have
been a small, posterolingual basin enclosed by the
posterior accessory cusp, large posterolingual cingular
cusp, and the rising posterior end of the crown. The
posterior crest of the posterior accessory cusp could
have interrupted the cingulum across the posterior end
of the crown.

Except around the apex of the principal cusp, most
of the enamel is missing from the buccal side of the
crown. The configuration of the remaining dentine
indicates the presence of at least two, distinct poste-
rior cingular cusps. There is no evidence of a buccal
cingulum connecting the posterior and anterior cin-
gular cusps. Dimensions of what remains of the crown
of AIII-348 are as follows: length = 2.67 mm; width =
1.39 mm. The crown was supported by two, large but
well divided roots.

Although somewhat crushed and distorted, AIII-
354 (Pl. 3:2) also appears to be a right, upper mola-
riform that in most respects is a duplicate of the
type. The few morphological differences most likely
reflect individual variation or difference in positions in
the dentition. Like the type, the anterobuccal cingu-
lar cusp apparently was smaller than the lingual, but
in AIII-354 it is clearly a terminus of the midline
crest of the principal cusp.

The posterior slope of the principal cusp is trans-
versely narrower than the body of the cusp and de-
marked from it by symmetrical vertical, buccal and
lingual depressions. These might be the result of post-
mortem distortion, but more likely are original fea-
tures of the tooth. Another possible difference from
ATII-348 is the apparent absence of posterobuccal
cingular cusps. The enamel is preserved over the
buccal side of the principal cusp, and a cingulum is not
present. Probably the two roots supporting the crown
were well separated.

Dimensions of the crushed crown of AIII-348 are
now: length = 2.85 mm; width = 1.09 mm. This
tooth and the type of Helvetiodon are larger than
would be expected for elements of the dentition of
Morganucodon peyeri, M. watsoni, or Hallautherium
(gen. nov., described below) and are in the predicted
size range of Tricuspes.

In his description of the fossils from Hallau PEYER
(1956) noted the presence of several fragments of
large, molariform, triconodont-like teeth. These, and
aspecimen in the new collection appear to be too
large to be parts of teeth of Morganucodon peyeri
and Hallautherium (gen. nov., described below), but
have amore complex morphology than would be
expected in teeth of Tricuspes tubingensis. Compari-
sons with the more complete molariforms just de-
scribed suggest that AIII-268 (PEyEr, 1956, Taf. 4,
Fig. 14) and AIII-303 (ibid., Taf. 7, Fig. 49) could be
fragments of the posterior ends of crowns of molari-
forms of Helvetiodon schutzi. AIII-390 (NC 60) and
ATII-437 (NC 204) might have had a similar origin.

ATII-270 (PEyer, 1956, Taf. 4, Fig. 16) preserves
part of the slope of what probably was the principal
cusp, posterior accessory cusp, and a cingular cusp.
On one side of the crown a crenulated cingulum
extends at least part way around the base of the
accessory cusp; the full extent of this cingulum and
morphology of the base of the other side of the crown
are unknown. PEYEr (ibid., p. 43) noted the “sym-
metrodont-like” disposition of the cusps of this frag-
ment. If what remains of the posterior crest of the
principal cusp is assumed to have extended directly to
its apex, then the cingular cusp does not lie on a line
defined by the apices of the principal and accessory
cusps. The angulation is not as great as that at the
junction of the anterior crest of the principal cusp and
the crest of the anterobuccal cusp of AIII-354 and,
probably, AIII-348. AIII-270 (PEver, 1956, Taf. 4,
Fig. 16) might be part of either an upper molariform
or an otherwise unknown (or unrecognized) lower
molariform of this species.

Premolariforms tentatively referred to Helvetiodon
schutzi: The collection from Hallau contains several
large premolariform teeth, probably too large to have
been parts of the dentition of Morganucodon peyeri.

Some of these have accessory and basal cingular cusps
suggesting they are elements of the dentition of Helve-
tiodon schutzi; others lacking such cusps might be parts
of the presumably morphologically simpler dentition
of Tricuspes tubingensis. For the sake of convenience
all are briefly considered here.

Many of the large premolariform teeth resemble
AIII-458 (Pl. 3:4). The principal cusp is not at the
center of the crown, but is offset toward the assumed
anterior end. Strong anterior and posterior crests
from the edges of the principal cusp whose relatively
great height suggests the tooth might be a lower
premolariform. Near the base of the crown the
anterior crest is deflected laterally to join a basal cin-
gulum, which is truncated by a fracture. Probably
the tooth lacked an anterior basal cusp. From com-
parisons with premolars of Morganucodon watsoni it
appears likely that the basal cingulum is on the lingual
side of the crown. The notch between principal and
posterior accessory cusps is not particularly deep. On
either side of this notch depressions extend basally; the
lingual depression is larger. Buccal and smaller,
lingual basal cusps are linked by a distinct, low crest.
The crown was supported by two, well separated
roots. Its dimensions are as follows: length =
1.47 mm, width = 0.77 mm.

The distal end of the crown of AIII-359 (NC 31) ıs
damaged but the tooth appears to be essentially a
duplicate of AIII-458 (width of crown = 0.84 mm).
AIII-334 (NC 6) is similar to but smaller (length of
crown = 0.99 mm, width = 0.48 mm) than the two
teeth just described and its posterior basal cusps are
not as large. It was supported by two distinct roots.

Proportions of the crown of AIII-302 (PEyver, 1956,
Taf. 7, Fig. 48) are slightly different from those of
AIII-458, but easily could be encompassed within the
range of individual variation of homologous teeth.
The apex of the principal cusp of AIII-302 has been
blunted; apparently by contact with foodstuffs and
not post-mortem abrasion. Dimensions of the crown
are as follows: length = 1.42 mm; width = 0.77 mm.

PeyEr (1956) thought AIII-265 (ibid., Taf. 7,
Fig. 11) was part of the posterior end of a premolari-
form. The fragment is in the same size range as most
of those premolariforms just described (crown width
= 0.84 mm). Configuration of what is preserved of
the crown suggests it is a fragment of the anterior end
of a premolariform differing from AIII-458 in the
presence of a anterior basal cusp. A weakly devel-
oped lateral cingulum extending to the apex of this
basal cusp might be on the lingual side of the crown.

AIII-402 (NC 72) and AIII-459 (NC 129) appear
to be fragments of large, two-rooted premolariforms
each having a small, ?anterior basal cusp but lacking
lateral basal cingula. A large segment of the root of
AIII-459 is preserved and exhibits a slight but dis-

tinet curvature toward the midpoint of the crown.
There is no evidence of expansion of the root but part
of its tip is missing.

Although what little is preserved of its crown does
not closely resemble those of any of the other large
premolariforms, one of the roots of AIII-393 (NC 63)
is preserved. It is curved, strongly diverging from the
presumed vertical axis. Again, the tip is broken, but
there is no sign of expansion.

ATII-325 (PEveEr, 1956, Taf. 12, Fig. 71) is a small
fragment of what appears to have been a large pre-
molariform. One side of the crown (the side not
illustrated by PEYER, ibid.) is heavily damaged. The
width of the remaining part of the crown is 0.73 mm.
If the preserved basal region of the crown is its
anterior end, which seems more likely, then AIII-325
differs from AIII-458 in the greater complexity of
cingular development. If it is part of the posterior
end of the crown, it is of much simpler construction
than AIII-458.

AIII-360 (NC 32) is a complete premolariform but
is sligthly smaller than most of those described above
(crown length = 1.06 mm; width = 0.62 mm). Its
crown consists essentially of the principal cusp.
A small basal cusp is present at the posterior end of
the crest of the posterior ridge of the principal cusp.
Just lateral to this basal cusp on the slightly more
bulbous, convex side of the crown is a short basal
cingulum. Most of the root(s) of the tooth is missing.
What remains shows some indication of subdivision
but does not clearly demonstrate whether the tooth
was double or single rooted.

AIII-424 (NC 94, Pl. 3:3) is a small premolari-
form that, except for its large size (crown length =
0.73 mm; width = 0.40 mm) is similar to P, or P, of
Morganucodon watsoni. The crown is simple con-
sisting of an anteriorly canted principal cusp, two
cusps on the lower part of the posterior crest of the
principal cusp, and a simple cingulum along the antero-
basal (?lingual) side of the crown. Although there is a
vertically oriented depression on the ?buccal side of
the root, a similar depression is lacking from the oppo-
site side. The crown of AIII-439 (NC 109) is similar
to that of AIII-424 but slightly larger (crown length
= 0.92 mm, width = 0.44 mm). A depression on one
side of the root of this tooth, which also is probably an
anterior premolar, separates it into two lobes. The
crown of AIII-291 (PEver, 1956, Taf. 8, Fig. 37) is
similar to those of the two premolariforms just describ-
ed but it is significantly larger (length = 1.47 mm;
width = 0.73 mm). AIII-259 (ibid., Taf. 11, Fig. 5)
might be the crown of an anterior premolariform or
an incisor.

Incisiforms and caniniforms: Finally, and primarily
for the sake of completeness, teeth that might be
incisiforms or caniniforms of Tricuspes or Helvetio-

don are noted in the list of referred material. All
appear to be too large to be referable to either Mor-
ganucodon or Hallautherium (gen. nov. described
below). If haramiyids were not multituberculate-like in
the morphology of the anterior part of their dentitions
(a common working assumption based on no conclu-
sive evidence), the derivation of some of the teeth
from dentitions of these animals is also possible.

Discussion: The possibility that teeth al-
located to Helvetiodon might be parts of the dentition
of Tricuspes was considered. It can be suggested that
Tricuspes is based on lower molariforms and Helve-
tiodon on upper molariforms of the same taxon.
However, the difference in degree of development of
their basal cingula and of the separation of their roots
argue against this possibility. Another hypothesis is
that Tricuspes is typified on premolars of Helvetio-
don, which could explain the differences in cingular
structure. Again the differences in morphology of the
roots (those of Tricuspes being only incipiently
divided while the molariforms of Helvetiodon were
supported by two well-divided roots) and the presence
in the sample of several large, two-rooted premolari-
forms more likely referable to Helvetiodon argue
against this hypothesis. On the limited data available
a third hypothesis, that Tricuspes and Helvetiodon
are distinct taxa, appears to be slightly more probable.

Order and Family incertae sedis
Hallautherium gen. nov.

Etymology: Hallau; Ther, Greek, beast.
Typespecies: Hallautherium schalchi sp. nov.
Diagnosis: Asforthetype and only species.

Hallautherium schalchi sp. nov.

Etymology: Named for Ferdinand Schalch
whose studies of the Triassic- Jurassic boundary
resulted in the discovery of the fossil locality near
Hallau.

Type specimen: AIII-318 (PEveEr, 1956,
LXIV, Taf.5, Fig.64 & Text-figs.. 2a—b; Fig. 5),
left lower molariform preserved in a fragment of
dentary.

Diagnosis: Only known from lower molari-
forms with a main row of four cusps and one or more
anterior and posterior lingual cusps. These molari-
forms lack a basal, lingual cingulum or kühnecone.
Unlike any known morganucodontids a large, poste-
rior buccal basin is present on the type (a small de-
pression on the referred specimen). Teeth are in the
size range of Morganucodon watsoni and M. peyeri,

but are smaller than those of Tricuspes and Helveti-
odon.

Referred material:

AIII-337 (NC 9, Pl. 3:5), isolated lower molari-
form, right.

Description: The orientation of the type
specimen (Fig. 5) suggested here differs from that
proposed by P£yEr (1956) and utilized by Horson
and CromrTon (1969) and PARRınGToN (1978). That
the tooth is a lower molariform is clearly demon-
strated by the fragment of dentary in which it is
implanted. The principal cusp is anterior to the
midpoint of the crown length (anteroposteriorly).

Two lines of evidence suggest the tooth is a left
rather than a right lower molariform. The fragment
of dentary of AIII-318 preserves essentially a full
cross section of this bone (see PEYER, 1956, Taf. 5,

Figure5: Outline drawing of AIII-318, Hallautherium
schalchi, Hallau local fauna, Switzerland. A. lingual view,
B. occlusal view, C. buccal view. Scale equals 1 mm.

Fig. 64, and Text-figs 2a—b). Directly behind the
molariform there is a deep depression in the dentary.
If this is part of the wall of a dental crypt, it suggests
that at time of death the preserved molariform was
near the posterior end of the horizontal ramus of the
dentary. In support of this interpretation, a low
ridge along the posterior part of the top of the dentary
lateral to the molariform appears to be the anterior
end of the coronoid process. As far as known the
coronoid process of the dentary of advanced mammal-
like reptiles and early mammals lies either in line with
or, usually, buccal to the posterior teeth. A second
line of evidence is the apparent development of buc-
cal wear facets on AIII-318 and presence of a large
wear facet on the referred specimen (AIII-337,
RI35):

If identification of AIII-318 as a posterior molari-
form is correct, the absence of indications of a lingual
groove to house the splenial and, possibly, the preartic-
ular and angular, as well as “Crompton’s groove”
(see PARRINGToN, 1971) is of some significance. In a
homologous section of a dentary of a young individual
of Morganucodon watsoni both grooves, particularly
the former would be expected to be present (note
PARRINGToNn, ibid., fig. 10e—f). Enough of the surface
of the dentary of AIII-318 is preserved to suggest the
apparent absence of these grooves is not a result of
post-mortem abrasion. Thus, possibly the mandible
of Hallautherium schalchi was more mammal-like in
construction than that of Morganucodon watsoni and
other approximately
dontids.

contemporaneous MOrganuco-

The crowns of the lower molariforms are dominated
by the relatively high principal cusp, situated anterior
to the midpoint of the crown. Of the two accessory
cusps the posterior is distinctly larger. The central
row of cusps is completed by a small, posterior cusp
set slightly buccal to the line formed by the other
three. On AIII-318 there are two cusps lingual to the
anterior accessory cusp. Of these the cusp in the most
lingual position is the smaller. On AIII-337 only one
major cusp is present lingual to the anterior accessory
cusp, but a small cuspule is developed on its posterior
slope (Pl. 3:5). Both teeth have a small posterolin-
gual cusp lingual to the last cusp of the main row.
There is no evidence of even slight development of
either a cingulum between the anterior and posterior
lingual cusps or a kühnecone.

Although closely similar in all characters described
so far, AIII-318 and AIII-337 differ in structure of
the buccal side of their crowns. On AIII-318 a
distinct basin is present low and buccal to the posteri-
or accessory cusp and the last (posterior) cusp of the
main row. The buccal rim of this basin is smooth, but
in comparison to adjacent parts of the crown differen-

ces in the texture of the rim and internal surface of the
suggest the presence of wear facets. The degree to
which attrition could have modified the configuration
of the basin and its buccal rim cannot be assessed.
Anterior to this basin the buccal surface of the crown
is not interrupted by a cingulum or cusps. In contrast,
AIII-337 lacks a distinct posterior buccal basin. A
well-defined elongate wear facet lies along the buccal
surface of its posterior accessory cusp. Posterior to it
isa small basin-like depression.

Both teeth appear to have been supported by two,
well separated roots. Of the two fossils, AIII-318 is
distinctly the larger, length = 1.39 mm, width =
0.66 mm. Dimensions of AIII-337 are length =
1.08 mm, width = 0.44 mm. As long as the positions
of these teeth in the dental arcade remain unknown,
it is impossible to directly compare the size of Hallau-
therium schalchi with the known species of morganuco-
dontids. However, assuming that AIII-337 is not the
most posterior of the lower molariforms their dimen-
sions suggest the dentition of H. schalchi was approxi-
mately in the size range of that of Morganucodon wat-
soni and M. peyeri but smaller than Tricuspes.

Discussion: Several paleontologists (e. 8.,
PArrınGTon, 1978) have noted the differences between
the type specimen of Hallautherium schalchi and the
large samples of teeth of Morganucodon watsoni from
localities in Wales. Size and/or configuration of cusps
also clearly distinguish Hallautherium from Mega-
zostrodon and Erythrotherium. However, there is
a basic similarity in the overall configuration of their
crowns, which are dominated by a central row of three
or more cusps. This similarity is interpreted to be a
common trait of many advanced mammal-like reptiles
and early mammals in which increased complexity of
the crown was achieved simply by multiplication of
cusps along an anteroposterior (mesiodistal) axis.

The key difference between Hallautherium and
known morganucodontids is the extreme development
of the posterobuccal basin on at least one of the lower
molariforms. Posterobuccal cusps occur on a few
lower molars of M. watsoni (PARRINGToN, 1978), and
Mırrs (1971) noted the presence of a “suggestion of a
cingulum on the buccal surface” of M, of M. oehle-
ri. However, the presence of such a large buccal
basin, which appears to have occluded with a cusp(s)
of an upper molariform, is unknown in any species of
Morganucodon, Erythrotherium, Megazostrodon or
Eozostrodon. By the admittedly subjective standards
employed in the taxonomy of early mammals, recogni-
tion of a new genus and species appears warranted.
Whether the differences are indicative of a degree of
phylogenetic separation that might be recognized
through establishment of a new family is an assessment
that should await collection of additional material.

SYSTEMATIGHREPEATIONSEHIPS

The data currently available suggest that during the
Middle and Late Triassic a number of lineages of
cynodont therapsid reptiles diversified and indepen-
dently underwent selection for decrease in body size,
reduction in relative size of many elements of the
lower jaw, increased complexity of dental morphology
and occlusal pattern, and other characters of the mam-
malian grade of organization (see CROMPTON and
Jenkins, 1979). If better known evolutionary radia-
tions of other groups of vertebrates can be used as
models, probably many characters now taken as diag-
nosticof mammals evolved in parallel in distinet
lineages. Also the models would suggest that most of
these lineages became extinct and were not represented
by descendants in Middle or Late Jurassic faunas.
Finally, if these assumptions are correct, the occur-
rence of species with a mosaic of a primitive grades of
mammalian dental morphology and function but rep-
tilian grades in other skeletal traits must be expected.
Proper taxonomic allocation of such species has to
await discovery of specimens yielding more than just
information on dental morphology.

The class and ordinal affinities of many of the
vertebrates in the local faunas of the Tübingen-Stutr-
gart area and Hallau that are known only from mam-
mal-like teeth cannot be established on the meager
data available. Tricuspes is an excellent case in point.
The genus is now represented by isolated, fragmentary
teeth found at Gaisbrunnen, Hallau, and, possibly,
Sonnenberg bei Degerloch (D. SıGoGNEAU-RUSSELL,
pers. comm., has found teeth referable to Tricuspes at
Saint-Nicolas-du-Port). These teeth have some mam-
mal-like features: presence of three cusps that are not
aligned anteroposteriorly; development of a fourth,
?postero-buccal cusp; and at least incipient, if not full
subdivision of the root. However, beyond these there is
nothing suggesting mammalian affinity of the animal
that bore these teeth. Among the few known Middle
or Late Jurassic mammals or cynodonts none appear
to be descendants of Tricuspes. However, the avail-
able samples of Jurassic faunas probably give us only
limited documentation of their diversity. Though
descendants might be identified in the future, most
likely Tricuspes is a member of an advanced cynodont
or cynodont-derived mammalian lineage. Querried
allocation of Tricuspes to the Mammalia recognizes
the few mammal-like features of its teeth.

Although ranging from the Middle Keuper (Nor-
ian) to possibly the Bathonian (see (CLEMENS and
KIELAN- JAwoROWSkA, 1979), the Haramiyidae remains
a poorly represented group in the fossil record. Ha-
ramiyids are known only from isolated teeth found at
localities in Great Britain, France, West Germany, and
Switzerland. A jaw fragment containing two or more

teeth, an edentulous jaw, or any other skeletal material
of a haramiyid have yet to be discovered or recog-
nized. Current hypotheses concerning the systematic
relationships of haramiyids werereviewed by (CLrmEns
and KıELAn-JaworowskA (1979) but can be sum-
marized here as follows: Many workers, emphasizing
the mammal-like complexity of cusp morphology and
root structure, tentatively include the Haramiyidae in
the Mammalia. Some argue that haramiyids might be
ancestral or closely related to the ancestors of multi-
tuberculates, but there is division of opinion on these
hypotheses. Most likely the formally named taxa and
informal taxonomic groupings are based simply on
associations of morphologically similar teeth, and the
current intrafamilial classification primarily reflects
degrees of morphological similarity.

Review of the haramiyid teeth in the samples of
local faunas of the Tübingen-Stuttgart area and Hal-
lau revealed considerable morphological diversity.
Thomasia antiqua, Thomasia sp. 2 (Hann, 1973), and
?Thomasia sp. were identified in the collections from
the German localities. Specimens referable to Hara-
miya have yet to be found, but this could easily be a
product of the small sample sizes. Both form genera
are represented in the Hallau local fauna. Isolated
teeth of cf. Thomasia antiqna, T. anglica, ?Thomasia
sp., cf. Thomasia sp., Haramiya moorei, as well as
fragments of haramiyid teeth of uncertain specific or
generic affinity are present in this sample. Unfortu-
nately these fossils do not provide a key to understand-
ing the composition of the haramiyid dentition or the
systematic affinities of the group, but only document
greater diversity in dental morphology.

Since publication of PEyer’s (1956) monograph
many workers have recognized that at least one
species of morganucodontid was present in the Hallau
local fauna. Detailed analyses of the material sup-
ports this view revealing the presence of a species
closely resembling Morganucodon watsoni, M. oehleri,
and Erythrotherium parringtoni. In order to distin-
guish specimens of Morganucodon and Erythrother-
ium data on the relative proportions and sequential
morphologic differences of the cheek teeth are required
(Crompron, 1974). These are not available for the
Swiss species. Its allocation to Morganucodon, known
from localities in Europe and Asia, rather than Eryth-
rotherium, known only from South Africa, is based
solely on the biogeographic probabilities.

The known molariforms of Morganucodon peyeri
do not show particularly close resemblances to the
morganucodontid recently described by SıGoGNEAU-
Russerr (1978) in her preliminary report on the mam-
mals found at Saint-Nicolas-du-Port. Full evaluation

of the relationships of this animal must await further
study of the new material from France.

Molariforms of Morganucodon peyeri differ from
those of M. watsoni and M. oehleri in several morpho-
logical details that warrant recognition of a new spe-
cies. The possibility that the Hallau local fauna is
older than the local faunas from Rhaeto-Liassic fis-
sures in Wales invited testing the hypothesis that
M. peyeri was either ancestral to M. watsoni or docu-
mented a more primitive grade of evolution. Some
features tend to support these speculations. The buc-
cal and lingual cingula of the upper molariforms of
M. peyeri are not as large as those of M. watsoni.
Possibly the lower frequency in development of
expansions of the roots of the molariforms of M. peye-
ri is a primitive trait. Also, the relative rarity of
wear facets might be interpreted as indicating a more
primitive grade in evolution of precise occlusal pat-
terns

Although suggestive, none of these observations
strongly supports the hypothesis and all can be inter-
preted in other ways. The geological evolution of
western Europe during the Rhaeto-Liassic involved
reduction in size and subdivision of land areas. The
fossil record suggests Morganucodon or its ancestors
were wide spread over what is now Eurasia. During
the marine transgressions populations of terrestrial
vertebrates were subdivided and isolated. They ap-
pear to have evolved independently to produce a series
of distinct insular faunas.. Morganucodon watsoni
and M. peyeri probably represent different lineages
formed during this radiation.

Three isolated teeth from Hallau are identified as
?Morganucodon sp. Although illustrating
features also found in morganucodontids, for example
the presence of three principal cusps aligned antero-
posteriorly, their crowns lack others, such as distinct
cuspidate lateral cingula and kühnecones. The teeth are
of the proper size to have been elements of the dentition
of M.peyeri, perhaps posterior premolariforms, decidu-
ous premolariforms, or posterior molariforms. Also,
it is quite possible that they are molariform teeth of a
primitive triconodontid or a hitherto unknown family

some

of mammals.

Two new genera and species of vertebrates, prob-
ably mammals, are recognized in the Hallau local
fauna. The teeth used to typify Helvetiodon schutzi
are relatively large and bulbous for elements of the
dentition of a Rhaeto-Liassic mammal. Although in
approximately the same range of size as Tricuspes, the
possibility that they are elements of the dentition of
this or a closely related genus appears unlikely at the
moment. As currently known, the molariforms of
Helvetiodon had two, large principal cusps, the cen-
tral being the larger. An anterior accessory cusp
similar to those found on molars of Morganucodon is

not present on the available teeth. Like Morganuco-
don upper molars, the molariforms of Helvetiodon
had buccal and lingual cingula, but the morphology of
the cingular cusps differs.

Recently FREEMAN (1979) described Wareolestes
rex from a single tooth found in deposits of Bathonian
age (Middle Jurassic) in the Forest Marble of
Oxfordshire, England. The type is a large tooth
(crown length = 2.31 mm; width = 1.24 mm, ibid.)
comparable in size to the type and referred molari-
form of Helvetiodon schutzi. However, the type of
Wareolestes appears to be an “enlarged” or “inflated”
version of a lower molar of Morganucodon watsoni.
As pointed out by FREEMAN (ibid.), the points of
resemblance include occurrence of a principal row of
four cusps and, although positioned somewhat anteri-
orly opposite the principal cusp, presence of an ap-
parent homologue of the kühnecone.
like most molars of Morganucodon, a subdued, non-
cuspidate cingulum is present on the buccal side of the
In contrast, although exhibiting some simila-

However, un-

crown.
rities, the molariforms of Helvetiodon are not so
closely comparable to the upper molars of Morganu-
codon.

Hallautherium schalchi, the second new genus of
mammals recognized in the Hallau local fauna, is
based on lower molariform teeth smaller than the
molariforms of Helvetiodon. The type specimen,
AIII-318, was described by PEyer (1956). As has
been argued above, the data suggest that PEver’s
identification of the buccal and lingual sides of the
tooth was in error. At least one of the lower molari-
forms of Hallautherium had a distinct posterior buc-
cal basin that might well have received and been
worn by a cusp of an upper molariform. Also, both
the type and referred specimens, apparently also a
lower molariform, lack kühnecones. Finally, the mor-
phology of the small fragment of dentary preserved in
the type suggests it was more mammal-like in con-
struction than that of Morganucodon watsoni. These
characters set Hallautherium well apart from any
known morganucodontid or other Rhaeto-Liassic
mammal.

Although following PEyEr (1956) in orientation of
AIII-318, Horson and CromPTon’s (1969) comments
on this fossil are still pertinent to the problem of
unraveling the ancestry of the multituberculates.
Among the known, non-therian mammals of the
Rhaeto-Liassic the general pattern of dental morpho-
logy is one of molariform teeth dominated by an
anteroposteriorly oriented row of three or more cusps.
The buccal side of the lower molariforms occluded
against the lingual side of the uppers. Basal cusps or
cingula normally occur on both sides of the upper
molariforms, but only on the lingual side of the
lowers.

Multituberculates first certainly appear in the fossil
record in the Kimmeridgian (Late Jurassic), but might
be recorded by a specimen of Bathonian age (Middle
Jurassic, FREEMAN, 1976) from Britain or an Early
Jurassic fossil found in India (DarTa et al., 1978).
Like other non-therians the cusps of the molars of
multituberculates are arranged in anteroposteriorly
oriented rows. Although yet to be documented, it
appears most likely that their molar pattern origi-
nated through the addition of basal cingula, which
evolved into rows of cusps lateral to the main row of
cusps. Evidence provided by the structure of their
premolars and relative development of cusp rows on
their molars suggests that multituberculate lower
molars and M! evolved through addition of a buccal
row of cusps to the primitive row while M? appears
to have originated by the addition of a lingual row of
cusps (see CLEMENS and KIELAN- JAWOROWSKA, 1979).
Currently this presumed pattern of addition of cusp
rows stands as the key apomorphy of the Multituber-
culata.

The importance of the dental morphology of Hal-
lautherium in considerations of the ancestry of multi-
tuberculates is not that these teeth exhibit apomor-
phies hitherto only known in multituberculates. 'They
do not. However, in being an exception to what has
been regarded as the standard pattern of cingular

development on molariform teeth of non-therians,
they add to the documented range of morphological
variation among these mammals. Thus they streng-
then the plausibility of the hypothesis calling for
origin of molars of multituberculates through a unique
pattern of cingular development. Unless there were
major reversals in the evolutionary trend in develop-
ment of these additional cingula and rows of cusps,
a correlary of this hypothesis is that the common
ancestors of multituberculates and other non-therian
mammals would be animals whose molariform teeth
lacked basal cingula. Clearly such a grade in dental
evolution would be appropriate for very early non-
therian mammals or cynodont reptiles.

In summary, the available collections of Rhaeto-
Liassic mammals from Switzerland and West Germa-
ny add to the documented diversity of mammalian
lineages at this time. These collections, and that being
assembled by SısoGnEAuU-RusseiL from a locality in
eastern France, clearly show that Rhaeto-Liassic
mammals can no longer be easily classified in just three
families, Morganucodontidae, Kuehneotheriidae, and
Haramiyidae. Distinctly different mammalian linea-
ges were present during this interval. Their diversity
tends to support the view that the first members of the
Mammalia are to be sought in older, Late Triassic or
possibly Middle Triassic faunas.

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IR EEIEN

Figure

Pilastiesit

All figures natural size

Pseudolissoceras zitteli (BURCKHARDT) .

1a—b, phragmacone with remains of To lan lererel el ateale views 6. e. N.
7325/1); 2a—b, phragmocone: lateral and ventral views (S. G. N. 7333/1). Vaca
Muerta Formation. Cerro Lotena. Lower Middle Tithonian. P. zitteli Zone.

Glochiceras steneri H. LEANZA, n. sp. . .

3a—b, phragmocone with somewhat ee Ben er el Anl ae views,
PARATYPE (S. G. N. 7333/5). Vaca Muerta Formation. Cerro Lotena. Lower
Middle Tithonian. P. zitteli Zone.

Hildoglochiceras wiedmanni H. LEANZA, n. sp. .

4a—b, phragmocone and body chamber: lateral mil earall views or HOLOTYPE
(G. P. I. T. 1545/1). Vaca Muerta Formation. Cerro Lotena. Lower Middle Titho-
nian. P. zitteli Zone.

Pseudolissoceras psendooolithicum (HaurT) : a a Ge
5a—b, phragmocone: lateral and ventral views (S. c. N. 7328/1). Vaca Muerta For-
mation. Cerro Lotena. Lower Middle Tithonian. P. zitteli Zone.

Parastreblites comahuensis H. LEAanzA, n. sp. .

6a—b—c, phragmocone: lateral, er! and el views oL HOLOTYPE (S. ‘c. N.

7326). Vaca Muerta Formation. Cerro Lotena. Lower Middle Tithonian. P. zitteli
Zone.

Page

Zitteliana 5, 1980

Leanza, H. A.: Lower and Middle Tithon Ammonite Fauna.

Zıtteliana 5, 1980

: Lower and Middle Tithonian Ammonite Fauna.

Plate 2

All figures natural size

Page

Virgatosphinctes mexicanus (BURCKHARDT) .

la—b, phragmocone and body chamber: fareral nd anal views es G. N. 8883).
Vaca Muerta Formation. Cerro Lotena. Upper Lower Tithonian. V. mendozanus
Zone.

Virgatosphinctes denseplicatus rotundus SPATH

2, phragmocone, lateral view of a young specimen ($. G. N. '8905/1); £ lateral view or
phragmocone (G. P. I. T. 1545/2). Vaca Muerta Formation. Cerro Lotena. Upper
Lower Tithonian. V. mendozanus Zone.

Choicensisphinctes choicensis (BURCKHARDT)

4a—b, phragmocone and body chamber (S. G. N. 8905/3): ee andl el: views.
Vaca Muerta Formation. Cerro Lotena. Upper Lower Tithonian.. V. mendozanus
Zone.

Virgatosphinctes andesensis (R. DouvıLı£) ee
5a—b, phragmocone and body chamber: lateral and rl views. "The specimen is

somewhat crushed laterally. (S. G. N. 8894/2). Vaca Muerta Formation. Cerro Lo-
tena. Upper Lower Tithonian. V. mendozanus Zone.

Figure

2,4:

35:

Plate 3

All figures natural size

Page

Choicensisphinctes choicensis sutilis H. LEAnza n. ssp. .

la—b, phragmocone and body chamber: lateral and al: views Koi HOLOTYPE
(S.G. N. 8902/1). Vaca Muerta Formation. Cerro Lotena. Upper Lower Tithonian.
V. mendozanus Zone.

Pseudinvoluticeras windhauseni (WEAVER)

2, lateral view of a phragmocone (S. G. N. 8900/5); ee, age Taceral and
ventral views (S. G. N. 8900/4). Vaca Muerta Formation. Cerro Lotena. Upper
Lower Tithonian. V. mendozanus Zone.

Pseudinvoluticeras douvillei SpaTH :

3a—b, phragmocong, internal mold: jaterall ac el views s(S. G. N. 8904/1); a
phragmocone with remains of body chamber, test preserved: lateral and ventral views
(S. G. N. 8904/2). Vaca Muerta Formation. Cerro Lotena. Upper Lower Tithonian.
V. mendozanus Zone.

Zitteliana 5, 1980

Leanza, H. A.: Lower and Middle Tithonian Ammonite Fauna.

Zitteliana 5, 1980 Plate 4

. A.: Lower and Middle Tıthonıan Ammonite Fauna.

Bölfastier4

All figures natural size

3, demaged, phragmocone and body chamber of PARATYPE, areral view = G N.
8902/2). Vaca Muerta Formation. Cerro Lotena. Upper Lower Tithonian. V. mendo-
zanus Zone.

Figure Page
1: Choicensisphinctes erinoides (BURCKHARDT) Aare 34
1la—b, phragmocone and remains of body chamber: re a el views (S. e. N.
8885/2). Vaca Muerta Formation. Cerro Lotena. Upper Lower Tithonian. V. mendo-

zanus Zone.
2: Psendinvoluticeras douvillei SpatH 23
2a—b, damaged phragmocone with remains GE body re: fereral ed rel views
(S. G. N. 8905/2). Vaca Muerta Formation. Cerro Lotena. Upper Lower Tithonian.
V. mendozanus Zone.
3: Choicensisphinctes choicensis sutilis H. LEANzA n. ssp. 34

Figure
1:

Plate5

All figures natural size

Aulacosphinctoides aff. A. hundesianus (UnHuic) ee
1a—b, phragmocone and body chamber: lateral and ee views (S. G. N. 3934/1). ken
Muerta Formation. Cerro Lotena. Upper Middle Tithonian. W. internispinosum Zone.

Virgatosphinctes burckhardti (DouvıLL£)

2a—b, fragment of phragmocone and body Seele fareral are) als views (S. e. N.
8896/1). Vaca Muerta Formation. Cerro Lotena. Upper Lower Tithonian. V. mendo-
zanus Zone.

Psendinvoluticeras (?) wilfridi (Douvırı£)

3a—b, phragmocene of a young specimen, lateral ad rei views 5 (8. G. N. 8898/1).
Vaca Muerta Formation. Cerro Lotena. Uppermost Lower Tithonian. V. mendozanus
Zone.

Virgatosphinctes evolutus H. LEANZA n. sp.

4a—b—c, phragmocone and body chamber real in Mar half & ne last or?
lateral, ventral and apertural views of HOLOTYPE (S. G. N. 8901/1). Vaca Muerta
Formation. Cerro Lotena. Uppermost Lower Tithonian. V. mendozanus Zone.

Page

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123:

2A):

Plate 6

All figures natural size

Page

Subdichotomoceras arancanense H. LEANZA, n. sp. . ö

1a—b, phragmocone and damaged body chamber: ereeil and eneral views © PA-
RATYPE (S. G. N. 8906/1); 3a—b, complete specimen, with phragmocene, body
chamber and aperture: lateral and ventral views of HOLOTYPE (S. G. N. 8935/1).
Vaca Muerta Formation. Cerro Lotena. Upper Middle Tithonian. W. internispi-
nosum Zone.

Aulacosphinctes proximus (STEUER)

2a—b, phragmocone and remains of body daniee areral nd nl views 1 G. N.
8944/1); 4a—b, phragmocone of a young specimen: lateral and ventral views
(S. G. N. 8922/1); 5a—b, internal mold of phragmocone and body chamber. (G.P.
I. T. 1545/3). Vaca Muerta Formation. Cerro Lotena. Middle part of the Middle
Tithonian. A. proximus Zone.

Corongoceras lotenoense SPATH
6a—b, phragmocone and damaged body er el andl enaalı views . = N.

8940/1). Vaca Muerta Formation. Cerro Lotena.. Upper Middle Tithonian
W. internispinosum Zone.

Plate 7

All figures natural size unless otherwise indicated

Figure Page

li:

Pachysphinctes americanensis H. LEANZA, n. sp. De
la, phragmocene fragment and body chamber: al view of the HOLOTYPE (S. ei N.
8952/1); 1b—c—d, upper, middle and lower ventral views of the last whorl of the same
specimen. All figures reduced X0.50. Vaca Muerta Formation. Cerro Lotena. Upper
Middle Tithonian. W. internispinosum Zone.

8942/4). Vaca Muerta Formation. Cerro Lotena. Upper Middle Tithonian. W. in-
ternispinosum Zone.

Zitteliana 5, 1980

LEAnzA, H. A.: Lower and Middle Tithonian Ammonite Fauna.

Zıitteliana 5, 1980

Lranza, H. A.: Lower and Middle Tithonian Ammonite Fauna.

Figure
1:

Plate 8

All figures natural size

Aspidoceras enomphalum STEUER

1a—b, phragmocene with remains of Body rember: Tereral an el views (S. ©. N.
8931/15). Vaca Muerta Formation. Cerro Lotena. Upper Middle Tithonian. W. in-
ternispinosum Zone.

Subdichotomoceras windhauseni (WEAVER) ee er.
2a—b, complete specimen: lateral and ventral views. S. G. N. 8940/2). Vaca Muerta
Formation. Cerro Lotena. Upper Middle Tithonian. W. internispinosum Zone.

Parapallasiceras aff- PD. psendocolubrinoides OLorız I:
3, lateral view of an incomplete specimen. (S. G. N. 8947/1). Vaca Muerta Formation.
Cerro Lotena. Upper Middle Tithonian. W. internispinosum Zone.

Windhauseniceras internispinosum (KRANTZ) . SE se
4a—b, inner whorls of the phragmocene: lateral and antallı views. (S. G. N. 8940/4).
Vaca Muerta Formation. Cerro Lotena. Upper Middle Tithonian. W. internispinosum
Zone.

Subdichotomoceras sp. juv. indet.

5a—b, phragmocone of a young specimen: fateral and re views 28 G. N 8942/2).
Vaca Muerta Formation. Cerro Lotena. Middle part of the Middle Tithonian. A. pro-

ximus Zone.

Parapallasiceras aft. P. reeticosta OLorız 3
6a—b, phragmocene with remains of body eben: Iateral and venrral views. (S.G.N.
8942/5). Vaca Muerta Formation. Cerro Lotena. Upper Middle Tithonian. W. inter-

nispinosum Zone.

Page

Plate 9

All figures natural size

Figure Page

ıl8

Windhauseniceras internispinosum (KRANTZ) . . a 0 ER IC 13)
la—b, complete specimen: lateral and ventral views. XS G. N. 8941/1). Vaca Muerta
Formation. Cerro Lotena. Upper Middle Tithonian. W. internispinosum Zone.

Hemispiticeras.aft. H. steinmanni (STEUER) er 43
2a—b, phragmocone: lateral and ventral views. (S. G. N. 8950/1). Vaca Muerta For-
mation. Cerro Lotena. Upper Middle Tithonian. W. internispinosum Zone.

Zitteliana 5, 1980

Leanza, H. A.: Lower and Middle Tıthonıan Ammonite Fauna.

Zitteliana 5, 1980 Plate 10

CLEMENS, W. A.: Rhaeto-Liassic Mammals from Switzerland and West Germany.

Fig. 1:

Fig. 2:

Fig. 3:

Fig. 4:

Fig. 5:

Pilfartien 180

Tricuspes tubingensis, type specimen, tentatively identified as a right lower molariform,
slightly retouched scanning-electron microscope photograph of lateral, probably buccal
side. Also, see E. von HuEne, 1933, Taf. 1, Fig. 7. Scale below photograph equals 1 mm.
Tricuspes tubingensis, type specimen, tentatively identified as a right lower molariform:
a, occlusal view, tentative orientation anterior to left, buccal upwards; b, lateral, probably
buccal view, anterior to right, and c, lateral, probably lingual view, anterior to left. Scale
above Fig. 2c equals 1 mm.

? Thomasia sp., Olgahain locality, GIT 1541/1, slightly retouched scanning-electron micro-
scope photograph of occlusal view. Scale below photograph equals 1 mm.

? Thomasia sp., Gaisbrunnen locality, first described by E. von Huene (1933, see Taf. 1,
Fig. 4). Slightly retouched scanning-electron microscope photograph of occlusal view.
Scale below photograph equals 1 mm.

Tricuspes cf. tubingensis, Hallau local fauna, AIII-351 (NC 23), tentatively identified as
a right, lower molariform: a, occlusal view, tentative orientation anterior to left, buccal
upwards; b, lateral probably buccal view, anterior to right; and c, lateral probably
lingual view, anterior to left. Scale below Figs. 5b-5c equals 1 mm.

Fig. 1:

Fig. 2:

Fig. 3:

Fig. 4:

Pilates]
All figures drawn same’scale. Scale below Fig. 4a equals 1 mm.

Morganucodon peyeri, type, Hallau local fauna, AIII-329 (NC 1), tentatively identified
as a right, lower molariform preserved in a fragment of dentary: a, occlusal view, tentative
orientation anterior to left, lingual upwards; b, lateral, probably buccal view, anterior
to left; and c, lateral, probably lingual view, anterior to right.

? Morganucodon peyeri, Hallau local fauna, AIII-368 (NC 40), tentatively identified as a
left, upper premolariform: a, occlusal view, tentative orientation anterior to right, lingual
upwards; b, lingual view; and c, buccal view.

? Morganucodon sp., Hallau local fauna, AIII-333 (NC 5), tentatively identified as a left,
upper molariform: a, occlusal view, tentative orientation anterior to left, buccal upwards;
b, lateral, probably buccal view, anterior to right; and c, lateral, probably lingual view,
anterior to left.

? Morganucodon sp., Hallau local fauna, AIII-340 (NC 12), tentatively identified as a left,
lower molariform: a, occlusal view, tentative orientation anterior to left, lingual upwards;
b, lateral, probably lingual view, anterior to right; and c, lateral, probably buccal view,
anterior to left.

Zitteliana 5, 1980 Plate 11

CLEMENS, W. A.: Rhaeto-Liassic Mammals from Switzerland and West Germany.

Zitteliana 5, 1980 Plate 12

CLEMENS, W. A.: Rhaeto-Liassic Mammals from Switzerland and West Germany.

Plate 12

Figures 1 and 2 drawn to same scale. Scale below Fig. la equals 1 mm. Figures 3 to 5 drawn to a

Fig. 1:

Fıgs2:

Fig. 3:

Fig. 4:

Fig. 5:

different scale. Scale below Fig. 3a equals 1 mm.

Helvetiodon schutzi, type, Hallau local fauna, AIII-348 (NC 20), tentatively identified as
a right, upper molariform, enamel-covered areas rendered in darker tones: a, occlusal view,
tentative orientation anterior to left, lingual upwards; b, lateral, probaly buccal view,
anterior to left; and c, lateral, probably lingual view, anterior to right.

Helvetiodon schutzi, Hallau local fauna, AIII-354 (NC 26), tentatively identified as a
right, upper molariform: a, occlusal view, tentative orientation anterior to left, lingual
upwards; b, lateral view, probably lingual view, anterior to right; and c, lateral view,
probably buccal view, anterior to left.

? Helvetiodon schutzi, Hallau local fauna, AIII-424 (NC 94), tentatively identified as a
right, lower, anterior premolariform: a, lateral view, probably lingual view; and b, lateral
view, probably buccal view.

? Helvetiodon schutzi, Hallau local fauna, AIII-458 (NC 128), tentatively identified as a
left, lower, posterior premolariform: a, occlusal view, tentative orientation anterior to
right, buccal upwards; and b, lateral view, probably lingual view.

Hallautherium schalchi, Hallau local fauna, AIII-337 (NC 9), tentatively identified as a
right lower molariform; a, occlusal view, anterior to left, buccal upwards; b, lateral view,
probably lingual view, anterior to left; and c, lateral view, probably buccal view, anterior
to right.

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Zitteliana

Abhandlungen der Bayerischen Staatssammlung für Paläontologie
und historische Geologie

Begründet von Prof. Dr. Richard Dehm

A. von HILLEBRANDT & R. SCHMIDT-EFFING

Ammoniten aus dem Toarcium (Jura)
von Chile (Südamerika)

Die Arten der Gattungen Dactylioceras, Nodicoeloceras,
Peronoceras und Collina

z
x MÜNCHEN 1981
SErFIT 87
£; = 3 P
er B RARIES -
u eurer ie

Gedruckt mit Unterstützung der
Deutschen Forschungsgemeinschaft

Herausgegeben von Prof. Dr. Dietrich Herm
Bayerische Staatssammlung für Paläontologie
und historische Geologie München

Redaktion: Dr. Peter Wellnhofer
ISSN 0373 -9627

Zitteliana

Abhandlungen der Bayerischen Staatssammlung für Paläontologie
und historische Geologie

Begründet von Prof. Dr. Richard Dehm

A. von HILLEBRANDT & R. SCHMIDT-EFFING

Ammoniten aus dem Toarcium (Jura)

von Chile (Südamerika)

Die Arten der Gattungen Dactylioceras, Nodicoeloceras,
Peronoceras und Collina

MÜNCHEN 1981

| _Ziteliana | 6 ] 7&seiten | 8 Tafeln | München, 7. Januar 1981 [ISSN 0373-9627

Gesamtherstellung: Druck- und Verlagsanstalt Gebr. Geiselberger, Altötting

3-74

München, 7. Januar 1981 ISSN 0373 — 9627

Ammoniten aus dem Toarcium (Jura)
von Chile (Südamerika)

Die Arten der Gattungen Dactylioceras, Nodicoeloceras,
Peronoceras und Collina

von

A. von HiLLEBRANDT* & R. SCHMIDT-EFFING*®*

mit 8 Tafeln und 26 Abbildungen

Aufteilung:

Einleitung: v. Hillebrandt

uno

. Paläontologischer Teil:

Fundpunkte (Profile): v. Hillebrandt

Dactylioceras und Nodicoeloceras: Schmidt-Effing
Peronoceras und Collina: v. Hillebrandt
4. Biostratigraphische Folgerungen: v. Hillebrandt und Schmidt-Effing

KURZFASSUNG

Aus 23 Juraprofilen der Hochkordillere Nordchiles
werden aus dem unteren und mittleren Toarcium, die dort
vorkommenden Arten der Gattungen Dactylioceras (Eo-
dactylites), Dactylioceras (Orthodactylites), Nodicoeloce-
ras, Peronoceras und Collina beschrieben. Insgesamt
werden 24 Arten bzw. Unterarten bekannt gemacht, von
denen 7 Arten bzw. Unterarten neu sind. Mit Hilfe der
Dactylioceratidae läßt sich in Chile das untere und mitt-
lere Toarcium biostratigrapisch in 6 Zonen bzw. Subzo-
nen unterteilen, die sich z. T. sehr gut mit gleichaltrigen
Zonen in Europa vergleichen lassen.

Die tennicostatum -Zone ist in 2 Subzonen gegliedert,
wobei die tiefere Subzone durch Dactylioceras (Eodactyli-

* Prof. Dr. A. von HILLEBRANDT, Institut für Geologie und
Paläontologie der Technischen Universität Berlin, Harden-
bergstraße 42, D-1000 Berlin 12.

* Doz. Dr. R. SCHMIDT-EFFING, Geologisch-Paläontologi-
sches Institut der Universität Münster, Gievenbecker Weg
61, D-4400 Münster.

tes) simplex charakterisiert wird, eine Art und Untergat-
tung des Mediterran-Bereichs. Die Leitform der höheren
Subzone ist Dactylioceras (Orthodactylites) tennicosta-
tum, das in Chile durch eine neue Unterart vertreten wird.
Das Zeitäquivalent der falcifer-Zone in Europa ist die
hoelderi -Zone, die durch Dactylioceras (Orthodactylites)
hoelderi n. sp. und Dactylioceras (Orthodactylites) he-
hianthoides gekennzeichnet wird. Letztere Art ist für den
pazifischen Raum (Japan, Kanada, Chile) typisch. Wie im
Mediterran-Gebiet tritt Peronoceras bereits in der basalen
bifrons-Zone auf und nicht erst in der mittleren bifrons-
Zone wie in NW-Europa. Die bifrons-Zone kann durch
neue Arten der Gattungen Peronoceras und Collina un-
tergliedert werden, die mit europäischen Artgruppen nahe
verwandt sind und einen biostratigraphischen Vergleich
ermöglichen. Es werden die Subzone des Peronoceras lar-
gaense, die Subzone des Peronoceras pacıficum und die
Subzone der Collina chilensis unterschieden. Im oberen
Horizont der chilensis-Subzone treten mit einem Durch-
messer von 16 cm die größten bisher bekannten Vertreter
der Gattung Peronoceras auf.

ABSTRACT

From 23 Jurassic profiles of the Northern Chilian high
Cordilleras species ofthe genera Dactylioceras (Eodactyli-
tes), Dactylioceras (Orthodactylites), Nodicoeloceras, Pe-
ronoceras and Collina are described which occur here in
the Lower and Middle Toarcian strata. Altogether
24 species, respectively subspecies are made known, 7 of
which arenew. The Chilian Lower and Middle Toarcıan
may be subdivided biostratigraphically by means of Dac-
tylioceratidae into 6 zones or subzones that partly may
well be compared with European zones of the same age.

The tenuicostatum zone is divided into 2 subzones,
whereby the lower subzone is characterized by Dactylio-
ceras (Eodactylites) simplex being a species and subgenus
ofthe mediterranean region. Dactylioceras (Orthodacty-
lites) tenuicostatum, represented in Chile by a new sub-
species, is the index fossil ofthe upper subzone. Chrono-
logically the European falcifer zone is equivalent to the

hoelderi zone which is characterized by Dactylioceras
(Orthodactylites) hoelderi n. sp. and Dactylioceras (Or-
thodactylites) helianthoides. The latter species is typical
for the Pacific region (Japan, Canada and Chile). Similar
to the mediterranean, Peronoceras already appears at
the basis of the bifrons zone and by no means
within the bifrons zone as known from northwestern Eu-
rope. The bifrons zone may be subdivided by new spe-
cies of the genera Peronoceras and Collina which show
close relationship with European species groups and
which render possible biostratigraphical comparison.
Three subzones as there are the subzone of Peronoceras
largaense, the subzone of Peronoceras pacificum and the
subzone of Collina chilensis are differantiated. With a
diameter of 16 cm, the largest represantatives of the genus
Peronoceras, so far known, do appear in the upper hori-
zon of the chilensis subzone.

RESUMEN

De los generos Dactylioceras (Eodactylites), Dactylioce-
ras (Orthodactylites), Nodicoeloceras, Peronoceras y Col-
lina se describe todas las especies encontradas en las capas
del Toarciano Inferior y Medio de 23 secciones del Jurä-
sico de la Cordillera Alta de Chile septentrional. En total
24 especies respectivamente subespecies estän estudiadas,
de las cuales 7 son nuevas. A base de los representantes de
la familia Dactylioceratidae se clasifica bioestratigräfica-
mente el Toarciano Inferior y Medio de Chile en 6 zonas
respectivamente subzonas las que permiten en general una
buena comparaciön con las zonas correspondientes de Eu-
ropa.

La zona de tennicostatum se divide en dos subzonas: La
subzona inferior estä caracterizada por Dactylioceras (Eo-
dactylites) simplex, un elemento muy mediterräneo, la su-
perior por Dactylioceras tenuicostatum chilense que es una
forma noroccidental europea por su especie, un elemento
end&mico en Chile por su subespecie. A la zona de falcıfer

de Europa corresponde en Chile la zona de hoelderi carac-
terizada por Dactylioceras (Orthodactylites) hoelderi
n. sp. y Dactylioceras (? Orthodactylites) helianthoides.
Esta especie es un elemento faunistico del ärea Pacifica
(Japön, Canadä, Chile). Peronoceras ya aparece en la base
de la zona de bifrons como en elärea mediterränea y noen
la parte media de la zona de bifrons como en Europa no-
roccidental. Nuevas especies de los generos Peronoceras y
Collina facilitan la subdivisiön de la zona de bifrons, las
cuales corresponden con grupos de especies europeas por
su filogenia y permiten asi una comparaciön bioestratigrä-
fica. Se distingue la subzona de Peronoceras largaense, la
subzona de Peronoceras pacificum y lasubzonade Collina
chilensis. En el horizonte superior de la subzona de chilen-
sis seencuentra con un diämetro de 16 cm los representan-
tes mäs grandes del genero Peronoceras conocido hasta
ahora.

INHALTISVERZEICHNIS

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1. SalardePedernalesi...2 4... 2er ne:
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„3. Quebrada Paipotito: aus easaussaeasaenene
. 4 Quebrada LaChaucha und Quebrada El Penon

. 5 Quebrada de Paipote bei Redonda
. 6 Quebrada ElBolito

. 9 Quebrada Portrerillos

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107 QuebradaBarganı nen ea nen aaa nne
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DRZEO uebradalklaretag gr re ee esseetete tete eieretetete 20

ZUISERSOA] Org UEtaWg ee ee ee a etete ne Pole ET SR Leer nelete ee er 21
ZAIAU Quebrada@alquisy ee ee tete Je Seretefelern 3 teteteteastereisieheleteletete 23
2.15 Rio Manflas, Profil zwischen dem Fluß und dem PortezueloElPadre ...............--- 24
28169 Rio, Budo este Verse elektersiefsteiekerste terre 24
2 ZARIO Mantlase ee seen mer else re nin Tele se neterele et are este arte 25
ZZ ProtlSalto.deliloroy erregen efeteieferelelerenentekebeteteret een lereferegeteneieleieiete 25
2A EZB HT untasdelOTO WERE EEE rel sekefsfeiersefeisfefieteie: 27
ZA SITE an STORE Rh ee een etetefetete.eferefelefefejeteroftefetalefetetsreretelegeferaratekefetetetejeickereleieie 28
2 SWProtilsüdlich@©nebradaEll@orralee mr ee ern eben erstekerereefetelteitetelhete 28
DIISEZEProHl@uebradal@hanchoquin/Baitepentr re ee etertefelefen este len derer a ejeieere 30
BERE alaontolosischerzliei Ev ee re ee re elerdkenteretete tens 31
BANG EnUSD)ZER) i0Cerasa EINATT TS ORT RT re N elasetsertne 31
3.1.1 Subgenus: Dactylioceras (Eodactylites) SCHMIDT-EFFING ....222eseeeeeeeneeeenennnn 31
3.1121 Dactylioceras((Eodactyhtes);simplex; FUCINI.. 2... ee aeansee een ese nn nennen. 31
3.1.2 Subgenus: Dactylioceras (Orthodactylites) BUCKMAN .. 2.222222 eeneeneneeneenenene 33
3.1.2.1 Dactylioceras (Orthodactylites) anguinum (REINECKE)......222eeseeeneeenenenennn 33
3.1.2.2 Dactylioceras (Orthodactylites) directum (BUCKMAN) ....22ceseeneeeneneneneneenn 34
3.1.2.3 Dactylioceras (? Orthodactylites) helianthoides YOKOYAMA .eneeeeneeeeeeeeeeeeee: 36
3.1.2.4 Dactylioceras (Orthodactylites) hoelderi n.sp. ..........-eeseeeeneeeeneenenennen 37
3.1.2.5 Dactylioceras (Orthodactylites) tenuicostatum chilensen. sp. ....«2222e2eseeeeeeennn 39
31.2260 Dach hocerasi(Orthodactyites)) sp 2 reelle een Reetleerelete een leiekelein hereleie 41
3.1.3 Subgenus: Dactylioceras (Dactylioceras) HXATT .......2222e2eeeeeeeneneeneeneeeenn 4
3,24Genus:NodicoelocerasiBUCKMAN TERN. 2 etale a sie ekelokeieie een eeletelerenfe nie elee le eheyaialeıe 4
3.2.1 Nodicoeloceras cf. pseudosemicelatum (MAUBEUGE) ......2222222eseeeeeeneeeeenenn 43
3.22) Nodicoelocerasich..eikenbergi,(HOEFMANN) 2. Sense ekleea seien onneneeeneseeaeneee 43
3.2.3 Nodicoeloceras ct..crassoides (SIMPSON) Form A... ....en aa neenee nennen nntee euere 44
3.2.4 Nodicoeloceras cf. crassoides (SIMPSON)FormB ..............222222es sense enn en 44
3.2.5 Nodicoeloceras cf. crassoides (SIMPSON)FormC ...........-2urssseeeeneeeneeneneeee 44
ZESEGENUSTRETONOCETASIHIKATTN1SOV N eeeeee et ete eretelefetstekmiesekeietelerete elereiszerste)e 45
3.3. 1 Peronoceras cf. subarmatum (XOUNG &BIRD).......-..-..--.-.esereeanennsesneene 46
SEI 2MRErONDCerASILATgaensernsp ehe ereeleeterele elete akekarcnrtetenetenereteistelstetefefeittle,eieteteselalereiatete 47
BESWaHReronocerasichTdesplacei (DAORBIENY)N 2 ee aeetgellen dessen tee ner 49
BEI ANReronocerasichätenzi (BINNASEILEVI-SETTI)E.oerefieeeiertelsieteleissetstofsnele olejespreiege elle eyeiate 49
SB SWR eronocerasictächolfatuRENZITERTE ee ee tesiseinserstelteiette 51
BES OBReronocerasipacificumsnaspaeer ekerenehnenuerelerste erehgeie ei eteielekeioteleiereieieteleie etekeieie eleielnneiere 51
SSMTER eronocerasichkVerticosun. BUCKMAN)ER ee eressersteseleserssatelehsiprolsuefslertese 53
3234 Br. Reronoceras ch" B..ch“ verticosum(BUCKMÄN)) „en seine Sereisretstelnanereieiei a ein eeiereeieieieiee 54
ZEIT ANPETONOCETASICHKVOTLEXI(SIMESON)Krre ei kereeietersesieretejeselefegere slejeyoie sielete Hlorereatelsieletegnte 55
SSR OWReronocerasiboltgenseinsp gr ee ee er oreteetsenlerter lee 56
ZB MWReronocerasieh1bohtoensenm sperren esferefekensteis sfencke eletereketorsgersterselsorreieenetee 58
SBMI2PReronocerasunerickeinAsprekrzeiserteteteelelene vererntelenagereoktefefereierefnserstafeiete.stereielenskeregaeee 59
BNlSmReronocerasietaplaniventernlGUER)E ee. seen meets see 61
BESMASRErOrOCerasIetAcrassicostatunä GUEX) en areas tele ekofaeotereretetafeleteletstoiens rs efeleielelere 61
ZEANGenus:/Gollina)BONAÄRBLLTNTBISE sereraneieeiee oieseninlefetereiere ersteieleieinle eiegeieinteleteleie eiejn elnieieieiete 62
BEA WM Collinzchilensisanssp:N meets stekeletersterforsteieloiersgerefefstere eretere eleleneger eier rare 63
AD CO NS DE SR gele skerekge ein Ko car tagen Yeleferakehejetsgetenerskrke eh tere re 66
49Biostratipraphische/Bolrerungenen eyes wetescte Setnieicheletetetesetseene elereloezeiefelatelekenerafetelnteieteraere 66
4.1 Zonedes Dactylioceras (Orthodactylites) tenuicostatum .......2.22222seeeeeeeeeeneen- 66
4.1.1 Subzone des Dactylioceras (Eodactylites) simplex .......2.2222222eeeeeeeeeeeeeenenn 67
4.1.2 Subzone des Dactylioceras (Orthodactylites) tennicostatum .........2.2.222eeeeeeene: 68
4.2 Zone des Dactylioceras (Orthodactylites) hoelderi .............22222seeeeenenenenenen 68
43% Zone.des’Hildocerasibifronsi sahen sense ale eanieie riet Helelkaan eis elasstansteister ste sangen 69
Ara] Subzonedes’Reronocerasllargaensenmenne ie ner ste sun skee eisen etenalehe aarerefegeterefalete ereietelene 69
43:25 Subzonedes’Beronoeerasipacıficumen. aeel eine ele esse eieele aleretofete eieterete = ielelelerejeteteielejekeie)e 71
43 34SuUbzonedenl@ollirsaichtlenssch Eee ee tee 71
438 \1DLIorizontnutiBeronocerasibolitnensekkm rate seven len ekevetaketeeteketersventetehere 71
4373.20 H-IorizontmitReronocerasimoenickeime ae ee enter: netnestehkelete taste et. 72

TEIteratur ee er ee era ee ee eaeer arniekersteinlelnietexeisteleetefetareteis ehe Mensa seien eietete ehe 73

Prof. Dr. Helmut Hölder
zum 65. Geburtstag gewidmet.

1. EINLEITUNG

Die Aufnahme der Profile, aus denen die Dactyliocera-
tidae stammen, erfolgte durch den ersten der beiden Auto-
ren in den Jahren 1966 bis 1968 während eines Aufenthal-
tes als Gastdozent am Departamento de Geologia der
Universidad de Chile in Santiago de Chile und im Süd-
sommer 1971/72 im Rahmen einer von der Deutschen
Forschungsgemeinschaft unterstützten Forschungsreise
nach Argentinien und Chile (v. HıLıesranpT 1970, 1971,
1973 a, b). Die bisher in Chile gefundenen Dactyliocera-
tidae stammen sämtlich aus Juraprofilen der Hochkordil-
lere zwischen der Cordillera de la Punilla im Süden (29°30’
südl. Br.) und der Cordillera Domeyko im Norden (25°
südl. Br.). Artlich bestimmbare Dactylioceratidae wurden
zwischen der Quebrada Chanchoquin (28°50’ südl. Br.)
und dem Salar de Pedernales (26°13’ südl. Br.) gefunden
(Abb. 1). Dactylioceratidae sind ım chilenischen Unter-
und Mittel-Toarcium (tenuicostatum- bis bifrons-Zone)
verhältnismäßig häufig, zumeist häufiger als die mit ihnen
zusammen vorkommenden Hildoceratidae. Die verschie-
denen Gattungen und Arten der Dactylioceratidae ermög-
lichen eine detaillierte biostratigraphische Unterteilung
des Unter- und Mittel-Toarcıum in Zonen, Subzonen und
Horizonte, die gut mit gleichaltrigen biostratigraphischen

Einheiten in Europa verglichen werden können. Aus die-
sem Grund erschien eine monographische Bearbeitung
dieser Ammoniten-Familie besonders wichtig und loh-
nend, besonders auch deswegen, weil bisher aus dem süd-
amerikanischen Jura nur eine einzige Art der Dactylioce-
ratidae beschrieben und abgebildet wurde (Rıcar 1930).

Allen Kollegen, Freunden und Institutionen, die diese
Aufsammlungen unterstützten und bei der Auswertung
behilflich waren, sei an dieser Stelle gedankt.

Zum Studium von Originalen und Vergleichsmaterial
wurden folgende Sammlungen aufgesucht: Bayerische
Staatssammlung für Paläontologie und historische Geolo-
gie in München, Staatliches Museum für Naturkunde in
Stuttgart, Institut und Museum für Geologie und Paläon-
tologie der Universität Tübingen, Geologisch-Paläontoli-
gisches Institut der Universität Freiburg i. Br., Naturhi-
storisches Museum Basel, Museum für Naturkunde der
Humboldt Universität in Berlin.

Das Belegmaterial zu dieser Arbeit wird in der Bayeri-
schen Staatssammlung für Paläontologie und historische
Geologie in München unter der Inventarnummer 1978 II
aufbewahrt.

2. FUNDPUNKTE (PROFILE)

Es werden nur diejenigen Fundpunkte aufgeführt, die
bei der Beschreibung der verschiedenen Arten berücksich-
tigt wurden. Daneben gibt es weitere Profile mit Dactylio-
ceraten, die jedoch bei der monographischen Bearbeitung
nicht ausgewertet wurden, da sie zu schlecht erhalten wa-
ren und zumeist artlich nicht bestimmt werden konnten.

Bei den meisten Fundpunkten wird das gesamte oder
zumindest ein Teil des Profils beschrieben, aus dem die
Dactylioceraten stammen, um einen besseren Überblick
über die Stratigraphie und Lage der Fossilhorizonte zu
ermöglichen.

Bei den Abbildungen der Profile wurden schichtparalle-
le, postjurassische Porphyritintrusionen weggelassen.

In den Fossillisten bedeutet ss = sehr selten, s = selten,
h = häufig und sh = sehr häufig.

2.1 SALAR DE PEDERNALES
(Abb. 1, Profil 1)

Das Juraprofil, aus dem mehrere Bruchstücke von Pe-
ronoceras cf. moerickei n. sp. stammen, liegt am West-
rand des Salars, etwa ın der Mitte zwischen den Punkten

3351 im Salar und 3610 westlich des Salars (Karte
1:100000, Blatt Potrerillos).

Die Mächtigkeit des Jura bis zum mittleren Bajocium
beträgt 350 bis 400 m.

Das Liegende bilden grünliche Tuffe der ? Trias. Der
Jura beginnt mit 12 bis 15 m mächtigen Sandsteinen, die
konglomeratische Lagen an der Basis enthalten. Etwa 8 bis
10 m über der Basis sind Fossilien häufig:

Montlivaltia sp. s

Modiolus sp. s

Entolium

Chlamys sp. s

Weyla sp. h

Myophorella catenıfera (HUPE) s
Pleuromya sp. s

Homomya neuquena LEANZA s
Radstockiceras sp. 1 s

Die Fauna gleicht der der Basisschichten des Portezuelo
de Pedernales und der oberen Quebrada El Asiento, die
dort in den oberen Teil des unteren Pliensbachium (+ da-
voei-Zone) zu stellen sind. Ungefähr 2 m über dieser Fos-
silschicht folgt ein Horizont mıt Atractites sp.

—
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28 2

— PROFILE
1-21 ım Text beschrieben

JURA PROFILE
IN DER
CHILENISCHEN HOCHKORDILLERE
ZWISCHEN
26° UND 29° SÜDL. BREITE

69° 30'

Abb. 1: Übersichtskarte mit Juraprofilen in der chilenischen Hochkordillere zwischen 26° und 29° südl.
Breite und Angabe der im Text beschriebenen Profile mit Dactylioceraten (1 bis 21).

Nach dem Hangenden zu wird die Schichtfolge kalkiger
und geht in dunkle, gut gebankte Kalke mit schiefrigen
Zwischenlagen über. Aus diesen Kalken (ewa 100 m über
der Basis) stammt Peronoceras moerickei n. sp., zusam-
men mit Harpoceras cf. subexaratum, Maconiceras sp.
und einer neu zu beschreibenden Gattung und Art der
Hildoceratidae. Diese Fossilschicht ist in den obersten
Teil des unteren Toarcıum zu stellen (chilensis -Subzone).

Knapp 200 m über der Basis enthalten die Bankkalke
Phymatoceras div. sp. und verkieselte Pelecypoden (Nu-
culana, Grammatodon, Myophorella, Mesomiltha, Rol-
lierella) .

Hangend folgen Schichten reich an Brachiopoden
(„Rhynchonella“, ‚‚Terebratula‘‘), weniger häufig sind
Pelecypoden, selten Ammoniten (Pleydellia cf. flnitans,
Bredyia sp.). Diese Schichten gehören dem Grenzbereich
Toarcium/Aalenium an.

Es folgen weiterhin Bank- bis Knollenkalke, bei 270 m
über der Basis mit großwüchsigen Entolium und Modio-
Ins.

In den hangendsten dunklen, bituminösen Bankkalken
kommen vor (v. Hırıesranpr 1970, S. 189; WESTERMANN
& Rıccarpı 1972, $. 20):

Dorsetensia romanı (OPPEL)
Dorsetensia liostraca BUCKMAN forma tecta BUCKMAN
Stephanoceras cf. humphriesianum (SOW.)

\ Quebr. EI Jardin

aQleb rada

Abb. 2:

Die Fauna ist in das mittlere Bajocium (humphriesia-
num-Z.one) zu stellen.

Aus den bituminösen Kalken gehen Kalke mit zuneh-
mendem Feinsandgehalt hervor, die ihrerseits in zunächst
Feinsandsteine, dann mittel- bis grobkörnige Sandsteine
der Asientos-Formation des Callovium übergehen.

2.2 QUEBRADA EL ASIENTO
UND PORTEZUELO DE PEDERNALES

Im Bereich der oberen Quebrada El Asıento wurden in
mehreren Horizonten Dactylioceraten gefunden. Auf der
Übersichtskarte (Abb. 2) sind sämtliche im Bereich des
Rio de la Sal, Portezuelo de Pedernales, Quebrada El Jar-
din, Quebrada El Asiento und Quebrada El Hueso aufge-
nommenen Profile angegeben. Die beschriebenen Dacty-
lioceraten stammen aus den Profilen 1, 3 und 4 (Abb. 2).
Das abgebildete Profil (Abb. 3) der oberen Quebrada EI
Asiento entspricht Profil 3 (Abb. 2). Die Fossilangaben
(Abb. 3) beziehen sich auf die Profile 3 bis 7, sowie 16.

Im Bereich der Profile 3 bis 6 (Abb. 2) transgrediert der
Jura auf Granit oder Porphyrit. An einigen Stellen greift er
taschenförmig mit einer Mächtigkeit bis ca. 5 m in den
Untergrund. Die Taschenfüllungen beginnen mit einer
groben Brekzie, die hauptsächlich aus dem aufgearbeite-

—— STRASSE
= QUEBRADA
1 PROFIL

Übersichtskarte über die im Bereich des Rio de la Sal, Portezuelo de Pedernales, Quebrada EI

Jardin, Quebrada El Asiento und Quebrada El Hueso aufgenommenen Profile. Profile 1, 3 und 4 mit im

Text beschriebenen Dactylioceraten.

* Sig. Perez ( mittl.Quebr. Asientos)
X%* _ Port.d. Pedernales
* %* %* mittl. Quebrada Asientos

CALLOVIUM ——

macrocephalus - Macrocephalites sp

R Pseudotoites sphaeroceroides
— @—Abbasites sp

Tmetoceras sp

Sonninıa (Euhoploceras) sp
Eudmetoceras klımakomphalum

Tsowerby/® —

concava

Lopha

AALENIUM

nem Eudmetoceras spp.

Poramma toceras sp, Podagrosıceras
+-Bredyia ssp, Parammatoceras sp 1
— Pleydellia ( Walkericeras)

Collina sp, Catacoeloceras sp

Peronoceras moericker

palmum
aalensis

chılensis 6=

pacificum

largaense

Peronoceras cf. verticosum

[erpeen= cf falcıfer
Peronoceras cf subarmatum
Hildaites cf serpentiniformis
Harpoceras sp.
Dact. (Orthod.) anguinum
Dact. (?Orthod.) cf. helianthoides

hoelderi

TOARCIUM

tenuicostatum

— len Pectinula cancellata 100m
Radstockıceras sp 2

Radstockiceras sp 2, Argutarpites

Reynesoceras cf acanthoıdes

Radstockiceras sp. 2 }
xx
Arıeticeras

Liparoceras (Becheiceras) sp *

ENSBACHIUM

Baal

{ Radstockiceras sp I
Protogrammoceras cf normanıanum xxx

Abb. 3: Juraprofile (Lias bis Basis Callovium) der Quebrada El Asiento (Abb. 2, Profil 3); intrusive, +
schichtparallele Porphyrite nicht berücksichtigt; Fossilangaben ohne Stern(e) aus den Profilen 3 bis 6
(Abb. 2), *Sammlung Perez (mittlere Quebrada El Asiento bei Profil 7, Abb. 2), ** Portezuelo de Pederna-
les (Profil 16, Abb. 2), *** mittlere Quebrada El Asiento (Profil 7, Abb. 2); Legende zur Gesteinsausbil-
dung Abb. 10.

ten Untergrund besteht. Es folgen Sandsteine, die zum
Hangenden hin kreuzgeschichtet sind. Fossilschutt tritt
bereits in der basalsten Schicht auf.

Über diesen Taschenfüllungen oder direkt über dem
Porphyrit bzw. Granit liegt eine konglomeratische Brek-
zie, die ebenfalls fehlen kann. Es folgen sandige Fossil-
schuttbänke mit einzelnen Geröllen und umgelagerten
Korallenstöcken.

Etwa 10 bis 15 m über der Basis (je nach Mächtigkeit der
Basalschichten) liegt zwischen zwei sandigen Fossil-
schuttkalkbänken eine um 50 cm mächtige, fossilreiche
Schicht (Schicht 1, Abb. 3). Am häufigsten sind Mu-
scheln, die vorwiegend doppelklappig erhalten sind, Ein-
zelklappen stecken ohne Orientierung im Sediment. Ko-
rallen und Brachiopoden sind seltener, Ammoniten und
Gastropoden sind sehr selten.

Andenipora liasica GERTH s

Montlivaltia sp. h

„Rhynchonella“ sp. s

‚„‚Terebratula“ sp. s bis h

Gryphaea sp. (kleinwüchsig) s

Lopha sp. ss

Modiolus cf. scalprus (SOW.) s

Modiolus cf. baylei (PHiLippi) h

Oxytoma sp. ss

Entolinm demissum (PHiLirps) h

Weyla sp. h

Myophorigonia neuquensis (GROEBER) ss
Myophorigonia sp. h

Jaworskiella burckhardti (Jaw.) s
Quadratojaworskiella pustulata (REYES & PEREZ) ss
Myopborella catenifera (HUP£) h

Mesomiltha hnayquimili (LEANZA) h

Astartidae gen. et sp. indet h

Protocardıa (?) sp. (= Gen. et sp. indet. in LEANZA) ss
Sphaeriola liasica (Carral TOLOSA) h

Pholadomya corrugata KOCH & DUNKER in LEANZA s
Pholadomya cf. plagemanni MÖRICKE in LEANZA s
Bucardiomya sp. ss

Homomya rotundocaudata (LEANZA) s

Pleuromya sp. s

Actaeon sp. s

Radstockiceras sp. 1 s

Bei den Profilen 7 und 16 (Abb. 2) kommt in dem glei-
chen Fossilhorizont zusätzlich Protogrammoceras cf.
normanıanum (D’ORB.) vor. Eine sehr ähnliche Fauna
wurde aus annähernd gleichaltrigen Schichten von Piedra
Pintada (Provinz Neuquen, Argentinien) (LEAnza 1942)
beschrieben.

Hangend folgen nochmals einige Fossilschuttkalkbän-
ke. Diese Serie geht allmählich über in dunkle, gut ge-
bankte, dichte Kalke, die mit Kalkmergeln wechsellagern.
In diesen Schichten kommen Radstockiceras sp. 2 und
Argutarpites sp. vor. Herr Perez (Santiago de Chile) fand
in diesen Schichten bei Profil 7 ein Liparoceras (Becheice-
ras) sp. Am Portezuelo de Pedernales ist im basalen Teil
dieser Schichtfolge ein fossilreicher Horizont ausgebildet:

„Rhynchonella“ sp. (2 Arten) h
„‚Terebratula“ sp. s

Modiolus sp. ss

Oxytoma sp. ss

Frenguelliella tapiai LAMBERT h
Mesomiltha huayquimili (LEANZA) sh
Cardinia sp. ss

Omphaloptycha sp. h

Cenoceras sp. ss

Phylloceras sp. s

Lytoceras sp. ss

Radstockiceras sp. 2 h

Arteticeras sp. s

Reynesoceras cf. acanthoides (REYNES) s
Atractites sp. s

Im Bereich der oberen Quebrada EI Asiento (Profile 2
bis 6, Abb. 2) ist in diese Kalkbankserie des oberen
Pliensbachium ein bis über 40 m mächtiger Porphyrit in-
trudiert, weitgehend schichtparallel (auf Abb. 3 weggelas-
sen).

Die Kalkbankserie wird im hangenden Teil dünnbanki-
ger und schiefrig. Einzelne Lagen bestehen aus Vollpfla-
stern von Pectinula cancellata Lranza (Schicht 3,
Abb. 3).

Hangend folgen zunächst wieder dunkle Bankkalke
und dann eine etwa 6 m mächtige Serie rostbraun anwit-
ternder Kalke mit geringmächtigen Mergelzwischenlagen
und folgender Fauna (Schicht 4, Abb. 3):

„Rhynchonella“ sp. h

„Terebratula“ sp. h

Propeamussium sp. h

Dactylioceras (Orthodactylites) anguinum (REINECKE) s
Dactylioceras (? Orthodactylites) cf. helianthoides YOKOYAMA s
Nodicoeloceras cf. crassoides (SIMPSON) Form B ss
Nodicoeloceras cf. crassoides (SIMPSON) Form C ss

Hildaites cf. serpentiniformis (BUCKMAN) ss

Harpoceratoides cf. alternatus (SIMPSON) ss

Über diesen rostbraun anwitternden Kalken liegen
knollige Kalke mit Peronoceras cf. subarmatum und
Harpoceras cf. falcifer im liegenden Teil (Schicht 5), Pe-
ronoceras cf. verticosum im mittleren Teil, Peronoceras
moerickei n. sp. im oberen Teil (Schicht 6) und Collina
sp. und Catacoeloceras sp. im hangendsten Abschnitt

(Schicht 7).

Bei Profil 1 (Abb. 2) (= Profil 3, Abb. 1) tritt im han-
gendsten Teil dieser Knollenkalke Peronoceras cf. vortex
auf. Über diesen Kalken des unteren Toarcium liegt ein 4
bis 6 m mächtiger, besonders an der Basis sandiger Fossil-
schuttkalk, der in sich 0,3 bis 1,0 m gebankt ist. Dieser
Fossilschuttkalk greift mit kleinen Taschen und Bohrgän-
gen (® 1 bis 3cm) bis 30 cm tief in die liegenden Bankkal-
ke. Im unteren Teil dieses Fossilschuttkalkes (Schicht 8)
kommt Pleydellia (Walkericeras) cf. flnitans und im obe-
ren Teil (Schicht 9) Bredyia sp. und ‚‚Parammatoceras“
sp. I vor.

Zwischen den Knollenkalken und dem Fossilschuttkalk
ist eine Schichtlücke vorhanden, die den größten Teil des
oberen Toarcium umfaßt.

Besonders in der hangendsten Bank ist bei allen Profilen
eine großwüchsige ‚„‚Terebratula“ häufig. Bei Profil 6
kommt auch eine Lage mit ‚‚Rhynchonella“ sp. vor. Mu-
scheln sind weniger häufig, bei diesen ist am häufigsten

Lopha, selten Chlamys, Modiolus, Pholadomya cf. pla-
gemanni und Pleuromya. Sehr selten sind reguläre See-
igel. Die Fossilien liegen nicht orientiert im Sediment. Die

Muscheln sind häufig doppelklappig.

Über dem Fossilschuttkalk folgen 4 bis 5m mächtige,
fossilschuttreiche, knollige Kalke, in denen ein groß-
wüchsiges Entolium (z. T. doppelklappig) häufig ist.
Etwa 2,5 bis 3 m über dem Fossilschuttkalk kommt ‚,‚Pa-
rammatoceras“ sp. 2 und Podagrosiceras cf. athleticum

vor (Schicht 10, Abb. 3).

Die Schichtfolge geht mit knolligen bis gut gebankten,
vorwiegend dichten Kalken mit mehreren Arten der Gat-
tung Eudmetoceras weiter. Eine 1,5 m mächtige Bank
(Schicht 12) setzt sich fast ausschließlich aus Zopha (vor-
wiegend doppelklappig) zusammen.

Hangend folgen wieder gut gebankte, seltener knollige
Kalke mit häufig desmodonten Muscheln (Pleuromya) im
hangenden Teil. Im hangendsten Abschnitt (Schicht 13)
kommen Eudmetoceras klimakomphalum und Sonninia
(Euhoploceras) vor. In Schicht 14 ist Tmetoceras häufig.
Schicht 15 enthält Abbasites und Schicht 16 Pseudotoites
sphaeroceroides.

Auf diese Serie transgrediert mit einem geringmächtigen
Konglomerat das Callovium. Das mittlere und obere Ba-
jocıum, sowie Bathonium fehlen.

2.3 QUEBRADA PAIPOTITO
(Abb. 1, Profil 4)

Die Quebrada Paipotito ist eine linke Seitenquebrada
der Quebrada San Andres. Im Jura dieser Quebrada
wurde 1966 ein Profil, 2 km oberhalb der Quebrada San
Andres, auf der rechten Talseite aufgenommen. Das glei-
che Profil beschrieben Cisternas & VICENTE (1976).

Das aus diesem Profil abgebildete Peronoceras cf. vor-
tex (Taf. 6, Fig. 1) stammt aus den basalen, 2 bis 3m
mächtigen, dunkelgrauen bis schwärzlichen, 5 bis 20cm
gebankten Plattenkalken, die mit intrusivem Kontakt an
graue Porphyrite grenzen. Aus der folgenden, mergelig-
kalkigen Serie mit Sandsteinen geben Cisternas & VICENTE
(1976) Phymatoceras (ob. Toarcium) an. Die bei diesen
Autoren als a4 bezeichneten Schichten enthalten Gry-
phaea cf. bilobata Sow., die im Aalenium der chileni-
schen Hochkordillere in mehreren Profilen vorkommt.
Die vorwiegend sandige Schichtfolge (a5 bei Cisternas &
VIcENnTE) im Hangenden muß zumindest im oberen Teil
dem Callovien zugerechnet werden, da in dieser Gry-
phaea cf. santiagensis Hurt (in GoTTscHE 1878) vor-
kommt. Es ist dies eine im Callovium von Chile und Ar-
gentinien weit verbreitete Art.

2.4 QUEBRADA LA CHAUCHA
UND QUEBRADA EL PENON
(Abb. 1, Profile 5a u. b; Abb. 3a)

Die Quebrada La Chaucha ist eine östliche Seitenque-
brada der Quebrada Vizcachas, die ihrerseits in die oberste
Quebrada de Paipote mündet. Das in der Quebrada La
Chaucha aufgeschlossene Juraprofil ist überkippt. Das
Liegende des Jura wird von Tonen und Sandsteinen gebil-
det, die Pflanzenreste der oberen Trias enthalten.

Der Jura beginnt mit einer 10 bis 15 m mächtigen Sand-
steinserie. Die obersten 1 bis 2 m sind als Fossilschutt-
sandstein mit Weyla entwickelt.

Die hangenden Schichten sind schlecht aufgeschlossen
und vorwiegend kalkig-mergelig ausgebildet. Aus dieser
Schichtfolge (etwa 20 m mächtig) stammen nicht aus dem
Anstehenden entnommene Dactylioceraten: Dactylioce-
ras (Orthodactylites) tenuicostatum chilense, Dact. (Or-
thod.) cf. directum, Dactylioceras sp., Peronoceras cf.
renzi, Peronoceras sp. Die Dactylioceras- Arten stammen
aus der tenuicostatum-Subzone, Peronoceras aus jüngeren
Schichten (largaense-Subzone).

Es folgt ein 2 m mächtiger Fossilkalk mit Bredyia sp.,
„Parammatoceras“ sp. 1, Lopha, Isognomonidae nov.
gen. nov. sp. (cf. Gervilleioperna), Ctenostreon cf. pecti-
niformis (v. SCHLOTH.), Trigonia, Mesomiltha, Neocras-
sina andinm (GOTTSCHE), Trigonastarte (?) steinmanni
(Mörıcke), Pleuromya „Terebratula“. Dieser
Fossilkalk ist in das basale Aalenium zu stellen. Er wird
von ammonitenreichen Kalkmergeln mit Eudmetoceras
und 7metoceras des mittleren Aalenium überlagert.

und

Etwa 35 m im Hangenden dieses Fossilkalkes enthält
ein 20 cm mächtiger Fossilkalk Sonninia (Papilliceras)
espinazitensis TORNQUIST und Pseudotoites sphaeroceroi-
des (Tornquist) des unteren Bajocium (Grenzbereich
„sowerbyi“/sauzei-Zone). Etwa 8 bis 10 m im Hangen-
den folgt ein 4 m mächtiger Sandstein, der von 35 bis 40 m
mächtigen Mergeln überlagert wird.

Die hangende, etwa 200 m mächtige, kalkig-sandige Se-
rie ist in das Callovium zu stellen.

Auf das Juraprofil der Quebrada El Penon machte mich
Herr J. Davıpson (Departamento de Geologia, Universi-
dad de Chile, Santiago de Chile) aufmerksam. Zusammen
mit ıhm nahm ich im Januar 1979 dieses Profil auf. Der
Profilausschnitt (Abb. 3a) wurde etwa 400 m unterhalb
der Lokalität El Penon (topographische Karte 1: 100000,
Blatt Laguna del Negro Francisco) auf der rechten Talseite
aufgenommen.

Die Transgression des marinen Jura auf eine mächtige
Serie von vorwiegend Sandsteinen der ? Trias ist auf der
rechten Talseite ca. 800m unterhalb der Lokalität El Pe-
non aufgeschlossen.

Der Jura beginnt mit einer oolithischen Bank, es folgen
Kalksandsteine (z. T. mit Fossilschutt), die in Mürbsand-
steine übergehen. Diese Schichtfolge ist etwa 7 m mäch-

Zone/Subzone
>
en)
=
ul
= ch
<< manazonge Eudmetoceras
<[ | opalinum | Bredyia, Parammatoceras
aalensis Pleydellia cf fluitans
moorei Pleydellia cf. lotharingica
thouarsense Phlyseogrammoceras
variabilis Phymatoceras cf. copiapense
Peronoceras cf pacificum 17
Harpoceras, Maconiceras 16
bifrons Harpoceras, Mercaticeras Peronoceras 1°
Harpoceras, Peronoceras cf subarmatum 13
Hildaites cf. levisoni, Nodicoeloceras cf. 12
crassoides Form A, Dact. (O)cf directum
>>
=) hoelderi
— Harpoceratoides cf alternatus, Nodicoeloceras sp 1
oO
x =
< E
[e) 50m
| tenuicostatum 1
Dactylioceras (0.) sp
Dactylioceras (0.) tenuicostatum chilense A
Dactylioceras (? Eodactylites) sp 5
implex :
SINE Nodicoeloceras cf eikenbergi 4
3
"Bouleiceras" 2
>2 - 5
= spinatus Bouleiceras
S EZ
U
Buleiceras? 0000... Bm 1
<
[a0]
u Modsokceras® oo
margaritatus | (Br
W g
a t Om

Abb. 3a: Teilprofil des Jura der Quebrada EI Penon (Abb. 1, Profil 5b); Legende zur Gesteinsausbildung

Abb. 10.

tig, und über ihr liegt die erste Fossilschicht mit Andeni-
pora liasica, ‚„‚Rhynchonella“, ‚‚Terebratula“, Gryphaea,
Pseudolimea, Mesomiltha und Pleuromya. Es folgen ca.
1 m mächtige, mürbe Fossilschichten mit härteren Kalk-
bänken, dann dickbankige (bis 1 m ©) Fossilschuttkalke
mit mergeligen Zwischenlagen und z. T. großwüchsigen
Weyla. Häufig ist ‚„‚Rhynchonella“. In der drittletzten
Bank kommt Pinna in Lebensstellung vor, und in der
obersten Bank ist Pholadomya häufig. Diese Schichten
sind insgesamt ca. 10m mächtig und enthalten folgende
Fauna:

„Rhynchonella“ sp.

‚„‚Terebratula“ sp.

Bryozoa gen. et sp. indet.

Gyyphaea sp.

Lopha sp.

Modiolus sp.

Gervilleioperna turgida LEANZA

Pinna sp.

Camptonectes sp.

Chlamys cf. textoria (SCHLOTH.)

Weyla sp.

Pseudolimea sp.

Mesomiltha sp.

Pholadomya corrugata KOCH & DUNKER in LEANZA
Pholadomya sp.

Actaeon sp.

Ammoniten wurden keine gefunden, jedoch läßt sich
die Fauna bei Vergleich mit anderen Lokalitäten in das un-
tere Pliensbachium einstufen.

Über diesen fossilreichen Schichten liegt eine etwa 8 m
mächtige Serie gut gebankter Fossilschuttkalke, die in
ebenfalls gut gebankte Kalke mit weniger Fossilschutt
übergehen. Im basalen Teil enthalten diese Kalke Rad-
stockiceras und Protogrammoceras und im höheren Teil
Radstockiceras und Argutarpites.

Die Schichtfolge des detailliert aufgenommenen Profil-
abschnittes (Abb. 3a) beginnt in den Kalken mit Radstok-
kiceras und selten Pectinula cancellata. Das oberste
Pliensbachium und tiefere Toarcium besteht aus einer
Wechsellagerung von mehr oder minder mergeligen, z. T.
knolligen Kalkbänken mit dunklen, z. T. bituminösen
Mergeln. Die Ammoniten dieser Serie lassen sich am be-
sten aus dem Grenzbereich der Kalkbänke zu den Mergeln
gewinnen. Pectinula cancellata tritt in dieser Serie wie-
derholt auf, daneben ist seltener Mesomiltha und Pleu-
romya vorhanden.

Bei Schicht 1 (Abb. 3a) ist eine 60 cm mächtige Kalk-
bank aufgeschlossen, in der schlecht erhaltene ‚Bouleice-
ras“ sp. (v. Hırıesranpt 1973a, S. 359) häufig sind.

Herr WIEDENMAYER (Naturhistorisches Museum Basel)
machte mich darauf aufmerksam, daß die von mir (v. HILLE-
BRANDT 1973a) aus Argentinien beschriebenen Bouleiceras sp.
nicht zu dieser Gattung zu rechnen sind, sondern große Ähnlich-
keit mit Ammoniten aufweisen, die von FucinI (1931) aus dem
obersten Pliensbachium von Sizilien beschrieben wurden. Nach
GUEX (1974) ist Tauromeniceras ein unmittelbarer Vorläufer von
Bouleiceras. Diese Gattung kommt auch im obersten Pliensba-
chium von Portugal (MOUTERDE 1967) und Südspanien (MOU-
TERDE et al. 1971) vor.

Auch in den folgenden Schichten treten Querschnitte
von „Bouleiceras“ sp. auf. Zwischen Schicht 2 (20 cm
Kalkbank mit Fossilschutt an der Basis und ‚‚Bouleiceras“
sp.) und 3 treten die letzten Querschnitte von ‚‚Boxleice-
ras“ sp. auf. Etwa 1,5 m hangend Schicht 2 wurden in ei-
ner bräunlich anwitternden, ca. 20 cm mächtigen Kalk-
bank (Schicht 3) die ersten nicht näher bestimmbaren und
unvollständigen Exemplare von Dactylioceras gefunden.

Die Schichten mit ‚‚Bouleiceras““ sp. sind in das oberste
Pliensbachium zu stellen. Das Toarcium beginnt mit
Schicht 3. Schicht 4 (20 cm Kalkbank) enthält eine Reihe
untereinander sehr ähnlicher Dactylioceraten, die nicht
direkt zu Dactylioceras (Eodactylites) gestellt werden
können, obwohl sie sicherlich nicht weit davon entfernt
sind. Es sind Formen die Nodicoeloceras cf. eikenbergi
entsprechen. Diese Art kommt in England im tieferen Teil
der tenuicostatum-Zone vor.

In Schicht 5 (30 cm Bank) treten Querschnitte kräftig
berippter Formen auf, die vielleicht zu Dactylioceras
(Eodactylites) zu stellen sind.

In Schicht 6 (10 bis 20 cm Bank) und 7 sind Dactylioce-
ras (Orthodactylites) tennicostatum chilense häufig, in
Schicht 6 kommt zusätzlich selten Nodicoeloceras sp. und
Dactylioceras (Orthodactylites) helianthoides vor.

Schicht 8 enthält Bruchstücke eines großwüchsigen
Dactylioceras (Orthodactylites) sp.. Etwa 1 m hangend
(Schicht 9) tritt ein schiefriger Kalk auf mit Weyla, Meso-
miltha, Pleuromya und nicht näher bestimmbaren Frag-
menten von Dactylioceras.

Ungefähr Im im Hangenden (Schicht 10) folgen fein-
sandige Kalke mit einer kleinwüchsigen ‚‚Terebratula“
und Propeamussium sp. Die hangende Schichtfolge be-
steht hauptsächlich aus Mergeln, die zu Beginn noch ge-
ringmächtige Kalkbänke und sehr häufig ‚‚Terebratula“
(kleinwüchsig) enthalten. Dann beginnt eine Serie aus
dm-gebankten (bis 30cm ®), bräunlich anwitternden
Kalkbänken. Etwa 1,5m über Beginn dieser Serie enthält
eine Bank (Schicht 11) häufig Harpoceratoides cf. alter-
natus und selten Nodicoeloceras sp. Diese Ammoniten-
bank kann bereits der hoelderi-Zone zugeordnet werden.

Im Folgenden treten wieder Bänke mit ‚‚Terebratula“
auf, denen Mergel zwischengelagert sind.

Schicht 12 ist eine 20 cm mächtige Kalkbank, an der Ba-
sis mit Nodicoeloceras cf. crassoides Form A und Dacty-
lioceras (Orthodactylites) directum und im oberen Teil
mit großwüchsigen Hildaites cf. levisoni. Direkt im Han-

genden schließt eine 1 m mächtige Kalkbank mit „‚Tere-
bratula‘“ an.

In den folgenden ruppigen Kalken (Schicht 13) tritt
Harpoceras sp. und Peronoceras cf. subarmatum, sowie
„Rhynchonella“, ‚Terebratula“, Eopecten und Phola-
domya auf. Dieser Fossilhorizont kann bereits in den tie-
feren Teil der bifrons-Zone (largaense-Subzone) gestellt
werden.

In den folgenden Schichten ist „‚Rhynchonella“ häufig,
Ammoniten sind selten, und es wurden zumeist nur
Bruchstücke gefunden. In Schicht 14 kommt Harpoceras
sp. und Mercaticeras sp. vor, in Schicht 15 Peronoceras
sp. und in Schicht 16 Harpoceras sp. und Maconiceras
sp-, Schicht 18 ist die letzte bräunlich anwitternde Kalk-
bank. In dieser Bank tritt „‚Rhynchonella“ nicht auf und
es wurde ein Peronoceras cf. pacificum gefunden.

Es folgt eine ca. 8 m mächtige Serie aus mikritischen,
grauen Kalken und Mergeln, in der ‚„Rhynchonella“ z. T.
häufig ist. Aus dieser Serie stammen Phymatoceras cf. co-
piapense, Phlyseogrammoceras und Pleydellia cf. lotha-
ringica. Die letzten Bänke dieser Serie sind etwas feinsan-
dig und dm-gebankt. Sie werden von einer Fossilschutt-
brekzie überlagert, die 50 cm über ihrer Basis häufig
Pleydellia cf. flnitans enthält. Außerdem kommen ‚,Te-
rebratula“, Lopha, Entolium, Chlamys und Trigonia
vor. Etwa 1,5 m über der Basis tritt eine für diesen strati-
graphischen Horizonttypische, neue Gattung und Art der
Isognomonidae (cf. Gervilleioperna) auf. Pleydellia cf.
flnitans kommt in mehreren Horizonten vor.

Darüber liegen petrographisch ähnlich ausgebildete
Schichten mit Bredyia sp. und Parammatoceras sp. und
über diesen Fossilschuttkalke mit Zopha und Eudmetoce-
ras Sp.

Auf der linken Talseite sind die Schichten mit Eudmeto-
ceras zumindest 30 m mächtig. Einige Bänke sind reich an
Gryphaea und auch Enrtolium tritt in mehreren Bänken
auf. Über den Fossilbänken mit Eudmetoceras liegen
Bänke mit großwüchsigen Gryphaea.

Die folgende Serie (ca. 40 m mächtig) besteht aus
schlecht aufgeschlossenen Lutiten, denen im mittleren
Teil eine 15 cm mächtige Kalkbank mit schlecht erhal-
tenen Sonninia (Papilliceras) sp. eingeschaltet ist. Diese
Serie ist bereits in das Bajocium zu stellen. Über ihr folgen
kalkige Sandsteine mit selten Belemniten.

Nach einer Aufschlußlücke (ca. 5 bis 10m Mächtigkeit
entsprechend) steht eine ca. Im mächtige Oolithbank an.
Darüber liegen sandige Kalkbänke mit ‚‚Terebratula“
(kleinwüchsig) und Nerinea. Es folgen grüne Tuffe, rote
Sandsteine und rote Tuffe, die ca. 5 bis Om mächtig sind.

Darüber ist eine mächtige Serie aus dickbankigen Kal-
ken aufgeschlossen, in denen Korallenstöcke und Östrei-
den häufig sind. Den dickbankigen Kalken sind gelblich
verwitternde Sandsteine mit einer großwüchsigen Meso-
miltha zwischengelagert. Im mittleren Teil treten auch

PL. TOARCIUM AALEN. ? CALLOV. |KREIDE
3 x
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Abb. 4:

Juraprofil der Quebrada Paipote bei Redonda (Abb. 1, Profil 6), Südflügel des Sattels auf der

rechten Talseite; Legende zur Gesteinsausbildung Abb. 10.

dichte Kalke auf. In der hangendsten Bank wurden Vau-
gonia sp., Mesomiltha (großwüchsig) und ein Abdruck
einer ? Reineckeia gefunden. Darüber liegen einige Meter
mächtige Bänke mit z. T. maßenhaft Gryphaea (klein-
wüchsig). Diese Dickbankserie ist etwa 200m mächtig
und ist wahrscheinlich in das Callovium zu stellen.

Im Hangenden folgen Vulkanite und über diesen sind
noch gelbliche, sandige Kalke und graue Kalke mit
schlecht erhaltenen ‚‚Trigonien“ aufgeschlossen. Diese
Serie läßt sich lithologisch gut mit den von v. HiLLEBRANDT
(1973 b, S. 179) in der Quebrada Cerros Bravos und Vi-
cunita gefundenen Schichten der tieferen Unterkreide ver-
gleichen.

2.5 QUEBRADA DE PAIPOTE BEI REDONDA
(Abb. 1, Profil 6, Abb. 4)

In der Quebrada de Paipote ist bei Redonda auf der
rechten Talseite ein Jurasattel aufgeschlossen. Das Profil
des Südflügels wurde aufgenommen (Abb. 4).

Der Sattelkern wird durch gebankte Feinsandsteine mit
Tonschieferzwischenlagen gebildet, die z. T. Pectinula
cancellata Leanza enthalten. Über einer 50 cm mächtigen
Feinsandsteinbank liegen ca. 12 m mächtige, feinschichti-
ge, schiefrige Kalke (mit Feinsandsteinbänken bis 10 cm
®) mit Vollpflastern aus Pectinula cancellata (Schicht 1,
Abb. 4). Die Pectinulaschiefer gehen in grünlichgraue
Feinsandsteine über und werden von 30 bis 40 m mächti-
gen, dünnbankigen Mergelkalken überlagert, die schlecht
aufgeschlossen sind. Es folgen knollige Kalke mit zum
Hangenden hin an Mächtigkeit abnehmenden, tonig-mer-
Aus diesen Knollenkalken
(Schicht 2, Abb. 4) stammen Peronoceras, Maconiceras,
Polyplectus und Frechiella cf. helvetica (v. HıLLEBRANDT
19732, /Laf.,2, Eıg..8),

geligen Zwischenlagen.

Die Knollenkalke gehen in sandige z. T. Fossilschutt
führende, z. T. knollige Kalke (Schicht 3, Abb. 4) über
mit Peronoceras cf. verticosum, P. cf. bolitoense, Collina
chilensis und einer neu zu beschreibenden Gattung und
Art der Hildoceratidae. Aus dieser Serie geht eine Sand-
steinserie hervor, die ihrerseits von z. T. dickbankigen
Konglomeraten (Gerölle bis 20 cm ®) und Sandsteinen
überlagert wird. Zum Hangenden hin werden die Sand-
steine allmählich wieder feinkörniger und feinschichtig.
Fossilien (Schicht 4, Abb. 4) sind selten: Entolium sp.
(großwüchsig), Endmetoceras sp. Der hangendste Teil
des Profils kann in das Callovium gestellt werden, wobei
allerdings die Grenze zum Aalenium nicht genau festzule-
gen ist. Über dem Callovium folgen Andesite.

2.6 QUEBRADA EL BOLITO
(Abb. 1, Profil 7; Abb. 5)

(= Quebrada La Tola bei v. Hırızsranpt 1973b,
Abb. 1) Die Quebrada EI Bolito (Karte 1:100000, Blatt
Laguna del Negro Francisco) ist eine Seitenquebrada der
Quebrada del Hielo, die ihrerseits in die Quebrada de Pai-
pote mündet. Der Anfang der Quebrada EI Bolito wird
auf dem Blatt Carrera Pinto als Quebrada La Tola und als
Quebrada EI Bolito eine weiter westlich liegende Que-
brada bezeichnet. Auf dem Blatt Laguna del Negro Fran-
cisco liegt eine als Quebrada La Tola bezeichnete Que-
brada 4 km östlich der Quebrada El Bolito. Die Quebrada
El Bolito teilt sich bei der gleichnamigen Vega in einen
westlichen (Quebrada Animitas) und östlichen Ast. Etwa
1,5 km südöstlich der Vega El Bolito ist in dem östlichen
Ast ein steilstehendes Juraprofil (Abb. 5) gut aufgeschlos-
sen.

Das Liegende des Jura bildet eine mächtige, konglome-
ratische, rote Brekzie mit kantengerundeten Blöcken bis
über 1 m Durchmesser. In den obersten 50 m sind die

Komponenten weniger groß, und diese Schichtfolge endet
mit einem ca. 2 m mächtigen, roten Konglomerat (Gerölle
bis 50 cm ®).

Es folgen konglomeratische Sandsteine, Brekzien und
Sandsteine mit Bruchstücken von Weyla und schließlich
gebankte Sandsteine (Schicht 1) mit viel Fossilschutt, ein-
zelnen Geröllen, sowie ‚‚Rhynchonella“, ‚‚Terebratula“,
Liostrea und Entolium.

Die Sandsteine gehen über ın sandige bis mergelig-kal-
kige Schichten (Schichten 2), in denen doppelklappige Pe-
lecypoden (Weyla, Pholadomya, Pleuromya, Pholado-
myocardia ) häufig sind. Aus diesen Schichten gehen knol-
lig-mergelige Kalke (Schichten 3) hervor, in denen eben-
falls doppelklappige Pelecypoden (Weyla, Modiolus cf.
baylei, Pholadomya corrugata, Homomya rotundocauda-
ta, Pleuromya) häufig sind. Im hangenden Teil dieser
knolligen Kalke kommen Cenoceras, Lytoceras und Rad-

stockiceras vor. Es folgen gut gebankte, vorwiegend
dichte Kalke, in denen Radstockiceras sp. 2 und Atracti-
tes (Schicht 4) auftreten.

Schicht 5 ist eine rostig anwitternde, etwas sandige Fos-
silkalkbank mit großwüchsigen Weyla sp. und Dact. (Or-
thodactylites) tenuicostatum chilense. Schicht 6 ist petro-
graphisch ähnlich ausgebildet und enthält Peronoceras cf.
subarmatum, P. largaense, Harpoceras cf. chrysanthe-
mum (YokoYamA) und Mercaticeras (?) sp. Anschließend
folgen mergelig-kalkige Schichten (Schichten 7), im basa-
len Teil mit häufig Brachiopoden, Modiolus, Gryphaea,
sowie Peronoceras pacificum, Harpoceras sp. und Poly-
plectus sp. Schicht 8 ist ein 1 Meter mächtiger, in sich 10
bis 20 cm gebankter Knollenkalk mit Peronoceras bolito-
ense n. sp., Collina chilensis n. sp., Harpoceras sp., Ma-
coniceras sp., Phymatoceras sp., sowie einer neuen Gat-
tung und Art der Hildoceratidae. An der Basis ist eine

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ZZ | pacificum Peronoceras pacificum, Harpoceras sp Polypledus sp {| 7
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Abb. 5: Juraprofil der Quebrada El Bolito (Abb. 1, Profil 7), Callovium nicht vollständig dargestellt;

Legende zur Gesteinsausbildung Abb. 10.

knollige, kalkig-mergelige, rötliche Schicht mit gut erhal-
tenen Exemplaren von Peronoceras und Collina entwik-
kelt. Schicht 9 besteht aus 10 bis 20 cm gebankten Kalken
mit Phymatoceras cf. erbaense und 2 Arten mit retrokli-
nen Rippen einer neu zu beschreibenden Gattung der Hil-
doceratidae.

Die Kalkbank von Schicht 10 enthält eine weitnabelige,
glatte Art dieser neu zu beschreibenden Gattung der Hil-
doceratidae. Über dieser Bank liegt ein fossilreicher, san-
diger, dickbankiger Kalk mit Pleydellia cf. flnitans im
liegenden Teil (Schicht 11) und Bredyia sp. und ‚‚Pa-
rammatoceras“ sp. 1 im hangenden Teil (Schicht 12).
Neben Ammoniten kommen in diesem Fossilkalk vor:

„Terebratula“ sp. h
Grammatodon sp. (großwüchsig) s
Isognomonidae nov. gen. nov.sp. (cf. Gervilleioperna) s
Trigonia sp. h
Myophorella sp. Ih
Myophorella sp. 2 h
Mesomiltha cf. bellona (D’ ORB.) s
Mesomiltha sp. (großwüchsig) s
Neocrassina andıum (GOTTSCHE) h
Trigonastarte (?) steinmanni (MÖRICKE) h
Pleuromya sp. s
Zwischen den Schichten 10 und 11 besteht eine Schicht-
lücke, die wie in der Quebrada El Asiento fast das gesamte
obere Toarcium umfaßt.

Schicht 13 enthält großwüchsige Entolium cf. demis-
sum (Philipps). Bei Schicht 14 sınd ca. vier 10 bis 30 cm
mächtige, rötliche Kalkbänke aufgeschlossen, in denen
Eudmetoceras div.sp. und Fontannesia austroamericana
Jaw. häufig sind.

Es folgt eine mergelig-kalkige Serie, im hangenden Teil
mit drei 10 bis 20 cm mächtigen, grauen bis rötlichen
Kalkbänken, die Eudmetoceras cf. klimakomphalum und
Sonninia (Euhoploceras) führen. Die anschließende Serie
rötlicher und bräunlicher, mittel- bis grobkörniger Sand-
steine mit Geröllen (bis 0,5 cm &) ist fossilleer. Darüber
beginnt eine mächtige Serie mit dickbankigen Sandsteinen
im tieferen Teil und ebenfalls dickbankigen Kalken mit
viel Fossilschutt im höheren Teil. Diese Serie kann dem
Callovium zugerechnet werden.

2.7 QUEBRADA CORTADERITA
(Abb. 1, Profil 8)

Am westlichen Beginn der Quebrada Cortaderita, auf
dem Bergrücken zwischen dieser und der nördlich an-
schließenden, unbenannten Quebrada (ebenfalls eine Sei-
tenquebrada der Quebrada Cortadera) ist ein Juraprofil
aufgeschlossen. In einem topogr. Sattel nordwestlich
Punkt 2819 grenzt eine Serie von Kalkschiefern und Kal-
ken, die einen Sattel bilden, an Intrusivgesteine. In den
Kalken kommt Radstockiceras vor.

In der westlichen Fortsetzung ist nach intrusiven Por-
phyriten eine Serie sandiger Mergel mit sandigen Kalk-

bänken aufgeschlossen, die z. T. rostbraun anwittern und
schlecht erhaltene Dactylioceraten und Harpoceras sp.
führen (+ hoelderi-Zone des unteren Toarcium).

Es folgteine etwa 20 m mächtige Serie dickbankiger (bis
über 1 m@), sandiger Fossilschuttkalke. Diese Serie endet
an einer Kuppe, an der die oberste Bank dieser Serie aufge-
schlossen ist.

Diese Bank ist stärker verwittert und enthält folgende
Fauna:

„Terebratula“ sp. h
Ctenostreon sp. s
Entolium cf. demissum (PHiLıpps) h
Trigonia sp. s
Neocrassina cf. andium (GOTTSCHE) h
Cenoceras sp. s
Peronoceras cf. vortex (SIMPSON)
Peronoceras cf. bolitoense n. sp.
Collina chilensis n. sp.
Harpoceras cf. subexaratum BONARELLI
Phymatoceras sp. ex gr. P. erbaense (v. HAUER)
Hildoceratidae gen. et sp. indet.
Die Fauna gehört dem Horizont mit Peronoceras boli-

toense der chilensis-Subzone an.

Über dieser Fossilschicht liegt eine etwa 5 m mächtige
Serie gebankter (5 bis 10 cm ®), bräunlich verwitternder
Sandsteine mit Phymatoceras sp. des basalen oberen To-
arcium. Es folgt ein 0,3 bis 1,0 m mächtiges Konglomerat
(Gerölle bis 5 cm ®). Die hangende Serie (60 bis 70 m
mächtig) ist auf der linken Talseite der unbenannten Que-
brada nördlich der Quebrada Cortaderita aufgeschlossen.
Diese Serie besteht aus vorwiegend dickbankigen Sand-
steinen mit einzelnen Konglomeratbänken (Gerölle bis
15 cm ®) und sandigen Mergellagen. Im hangenden Teil
kommen auch dickbankige Fossilschuttkalke mit Gry-
phaea, Pholadomya und Pleuromya, sowie in einem san-
digen, mürben Fossilschuttkalksandstein Gryphaea, Tri-
gonia, Pleuromya und Eudmetoceras vor. Zumindest die-
ser Teil der Serie kann in das Aalenium gestellt werden.
Das Juraprofil endet mit etwa 35 m mächtigen Mürbsand-
steinen (z. T. mit Geröllen), die an Vulkanite grenzen.

2.8 QUEBRADA YERBAS BUENAS
(Abb. 1, Profil 9; Abb. 6)

Das Gesamtprofil wurde von v. Hırıesranpt (1973,
Abb. 1,5. 175) dargestellt. Das Teilprofil (Abb. 6) wurde
auf der rechten Seite der Quebrada Yerbas Buenas aufge-
nommen.

Schicht 1 ist eine etwa 2 m mächtige Kalkbank (nimmt
nach Norden sehr stark an Mächtigkeit zu) mit häufig,
kleinwüchsigen Gryphaeen und selten einem großwüch-
sigen Coeloceras cf. pinguecostatum (BREMER) und einem
Eoderoceras aus der Gruppe des E. armatum (Sow.).
Schicht 2 besteht aus mergeligen Kalken und Kalkmergeln
mit zumindest 2 Arten der Gattung Uptonia.

Abb. 6:

>32
2
=
wu
=ı
<<
< | opalinum Bredyıa sp
Phymatoceras cf fabale, Phym. cf. Lilli
variabilis
Pe
chılensis Hıldoceratidae gen. et. sp.indet
P
=) Collina chilensis, Peronoceras moerickei
ll
2 Pei = fin f um P. Are Alam
x paci ficum ronoceras pacıfıcum, Pcf verliıcosum
L- 4
(@)
m
largaense
Peronoceras cf desplacei, P cf choffatı
hoelderi Harpoceratoides cf alternatus
Dact (Orthod.) hoelderi
tenuicostatum Pectinula cancellata_
spinatus Radstockiceras sp
|E are en
margaritatus
>3 a2 = 25
2 Protogrammoceras sp, Radstockiceras sp
| davoei
©
< ILL
[ee]
e ibex
=
= Ju —
a
Jamesoni
Uptonia
>3 raricostatum Coeloceras, Eoderoceras
ei
x
=)
>2
w
z
un

Teilprofil des Jura der Quebrada Yerbas Buenas (Abb. 1, Profil 9); intrusive, +

schichtparallele

Porphyrite nicht berücksichtigt; Legende zur Gesteinsausbildung Abb. 10.

Es folgen Mergel mit einzelnen Kalkbänken. Die Kalk-
bänke werden zum Hangenden hin mächtiger und die
Mergel geringermächtig. Bei Schicht 3 sind die Kalkbänke
bis 40 cm mächtig und enthalten häufig Protogrammoce-
ras und Radstockiceras.

Bei Schicht 4 sind die Kalkbänke wieder weniger mäch-
tig, und es kommt ebenfalls Radstockiceras vor.

Schicht 5 besteht aus etwa 10 m mächtigen, feinschich-
tig-schiefrigen Kalken mit Pectinula cancellata LEANZA.

Schicht 6 folgt direkt im Hangenden, ist etwa Im mäch-
tig und setzt sich aus bis 20cm mächtigen Kalkbänken zu-
sammen, die Dactylioceras (Orthodactylites) hoelderi, D.
(O.) directum und D. (O.) cf. directum enthalten. Dar-
über liegen 2 bis 3m mächtige, rostig anwitternde Kalke
(10 cm gebankt) mit Mergelzwischenlagen. Die oberste
(oder vorletzte) Bank (Schicht 7) istreich an Ammoniten:

Nodicoeloceras cf. crassoides (Simpson) Form A
Hildaites cf. serpentiniformis (BUCKMAN)
Hildaites cf. serpentinus (REINECKE)
Harpoceratoides cf. alternatus (SımP.)
Polyplectus sp.

Anschließend folgen wieder Mergel mit Kalkbänken,
bei Schicht 8 mit Peronoceras cf. desplacei, P. cf. choffati,
P. sp. exgr. P. subarmatum und Harpoceras cf. chrysan-
themum.

Schicht 9 enthält Peronoceras pacificum, P. cf. vertico-
sum, Maconiceras sp. und Polyplectus sp.

Ein Peronoceras cf. bolitoense (Taf. 7, Fig. 3), zu-
sammen mit Collina chilensis, Maconiceras sp. und einer
neuen Art (glatt) und Gattung der Hildoceratidae wurde
in etwas jüngeren Schichten gefunden.

Ein äufßeres Windungsbruchstück von Peronoceras
moerickei (Taf. 7, Fig. 2) dürfte aus etwa gleichalten
Schichten stammen.

In mehr mergeligen Schichten kommen bei Schicht 10
Bruchstücke einer neuen Art und Gattung der Hildocera-
tidae vor, die weitnabelig ist und retrokline Rippen be-
sitzt.

Bei Schicht 11 sind Kalkbänke mit sandig-mergeligen

Zwischenlagen aufgeschlossen. Es wurden Phymatoceras
cf. fabale und Phym. cf. lilli gefunden.

Diese Schichten werden von mit ca. 2 bis3 m Mächtig-
keit aufgeschlossenen Fossilschuttkalken (Schicht 12)
überlagert, die in einem Muldenkern die jüngsten Schich-
ten bilden. Sie enthalten Bredyia sp., Ctenostreon cf. pec-
tiniformis (v. SCHLOTH.) (großwüchsig), Myophorella,
Mesomiltha cf. bellona (D’Ors.), Mesomiltha (groß-
wüchsig), Myoconcha steinmanni (Jaw.), Pholadomya cf.
plagemanni und Pleuromya.

Zwischen den Schichten 11 und 12 ist eine Schichtlücke
vorhanden, die den oberen Teil des oberen Toarcium um-

faßt.

2.9 QUEBRADA POTRERILLOS
(Abb. 1, Profil 10)

Von der Quebrada Vaca Muerta erstreckt sich ein Jura-
gebiet nach Süden bis in die Quebrada Potrerillos. Das
Gesamtprofil wurde bei v. Hırızsrannr (1973b, Abb. 1)
dargestellt. Der tiefere Teil des Profils ist sehr gut in der
Quebrada Vaca Muerta aufgeschlossen. Das obere Sine-
murium ist vorwiegend sandig-konglomeratisch ausgebil-
det. Über einer 4 m mächtigen Grobsandsteinbank mit
einzelnen Geröllen beginnt eine sehr fossilreiche Serie
(hauptsächlich Brachiopoden) von sandig-mergelig-kal-
kigen Schichten mit einzelnen, dickbankigen, kalkigen
Sandsteinen bis sandigen Kalken. Die Oberfläche einiger
Bänke besteht aus Pflastern von Weyla. Diese Serie be-
ginnt ım obersten Sinemurium (Epideroceras (Pseudupto-
nia ?), Coeloceras) und reicht bis in das unterste Pliensba-
chium (Uptonia). Das mittlere und obere Pliensbachium
besteht aus etwa 50m mächtigen, 10 bis 20 cm gebankten,
dichten Kalken mit Kalkmergelzwischenlagen. In dieser
Serie kommt Radstockiceras vor. Die Serie endet mitmeh-
rere Meter mächtigen, feinschichtigen Mergelkalken, in
denen Pectinula cancellata Schalenpflaster bildet. Han-
gend folgen wieder gebankte Kalke mit Peronoceras und
Harpoceras.

In der Quebrada Potrerillos sind die Schichten sehr viel
stärker gestört und gefaltet als in der Quebrada Vaca Mu-
erta. Die Schichtfolge ist jedoch im hangenden Teil voll-
ständiger. Großtektonisch besteht die Schichtfolge des
Jura von Osten nach Westen aus einer Mulde und einem
anschließenden Sattel. Im Osten grenzt der Jura mit tek-
tonischem Kontakt an Granit. Die basale Sandsteinserie
und auch die darauffolgenden, fossilreichen Schichten
sind tektonisch stark verdünnt. Dem oberen Teil des unte-
ren Toarcium (pacificum-Subzone) gehört ein Fossilhori-
zont mit Peronoceras pacificum, P. cf. verticosum, Har-
poceras sp. und Maconiceras sp. an, der in den gebankten
Kalken über den Pectinula-Schiefern liegt.

Hangend folgen weiterhin vorwiegend dichte, gut ge-
bankte Kalke mit schiefrigen Zwischenlagen. Im obersten
Teil treten wenige Meter mächtige, mehr knollige Kalke
mit Phymatoceras (z. T. großwüchsig) auf.

Überlagert werden diese Schichten von ca. 4 m mächti-
gen Fossilkalken mit häufig Bredyia sp. (bis 0,5 m ©),
Myophorella, Neocrassina cf. andinm (GoTTscHE) und
Trigonastarte (?) steinmanni (Mör.) des unteren Aale-
nium.

Wie in der Quebrada Yerbas Buenas fehlt der obere Teil
des oberen Toarcium.

Die hangende, vorwiegend sandige Schichtfolge gehört
wahrscheinlich zum größten Teil dem Callovium an, die
den Muldenkern bildet. Der westlich anschließende Sat-
telkern wird von der basalen Sandsteinserie gebildet. Die
Basis wird jedoch nicht erreicht. Die Kalkserie des oberen
Pliensbachium und Toarcium ist stark spezialgefaltet, und
der Jura grenzt mit einer Ruschelzone an eine mächtige,
rote Sandsteinserie.

2.10 QUEBRADA LARGA
(Abb. 1, Profil 11; Abb. 7)

Der Jura der Quebrada Larga gehört zu einem Jura-
streifen, der sich von der Quebrada Larga im Süden bis zu
einer unmittelbar westlich der Quebrada San Pedrito und
mit dieser im Oberlauf parallel verlaufenden Quebrada im
Norden erstreckt. Profile wurden in dieser Quebrada und
in der Quebrada Larga aufgenommen. Das Gesamtprofil
der Quebrada Larga wurde bei v. Hırıesranpr (1973 b,
Abb. 1) abgebildet." Auf Abbildung 7 ist nur der obere
Teil dieses Juraprofils berücksichtigt.

Der basale Jura besteht aus einer 70 bis 100 m mächti-
gen Sandsteinserie, im Liegendteil schlecht gebankt, im
Hangendteil zunehmend kalkiger. Fossilien sind selten
und schlecht erhalten (Bruchstücke von Weyla, Frengnel-
hiella, Myophorigonia). Es folgen mehrere, 20 bis 30 cm
mächtige, graue Kalkbänke mit Zithotrochus humboldti
(v. Buch), Spiriferina, ‚„‚Rhynchonella“, Gryphaea dar-
wini Forses und Epophioceras sp. (1 Windungsbruch-
stück) (obtusum-Zone, Basis des oberen Sinemurium).
Über ihnen liegen wieder gebankte Sandsteine und eine ca.
15 m mächtige Serie von mehr oder minder kalkigen Mer-
geln mit einer 15 cm mächtigen Fossilschuttkalkbank. In
einzelnen Lagen ist Gryphaea tricarinata PhiLiri sehr
häufig, daneben kommen vor Spiriferina, ‚‚Rhynchonel-
la“, Chlamys, Weyla, Psenudolimea, Plicatula und Litho-
trochus humboldti.

Diese Serie wird zum Hangenden hin wieder sandiger
und der obere Teil des oberen Sinemuriums wird von einer
mächtigen Konglomeratserie gebildet, die von Sandstei-
nen überlagert wird.

Bei Schicht 1 (Abb. 7) sind diesen Sandsteinen gebankte
Kalke mit sehr häufig ‚‚Terebratula“ eingelagert.

Schicht 2 sind fossilreiche Kalksandsteine mit folgender
Fauna:

Andenipora liasica GERTH h
Montlivaltia sp. s

< Eudmetoceras sp.
Si — —
thouarsense Phymatoceras cf copiapense
voeriabilis_ Phymatoceras cf fabale, Phym ct lilli
chilensis Collina sp.,Peronoceras cf planıventer, P cf crassicostatum, Polyplectus sp.
= _l Osperlioceras sp ,Phym.ex gr. erbaense, Hildoceratidae gen et sp indet.
>
— | pacificum
oO — — — —— +
x la rgaense Peronocerus largaense, Pcf subarmatum, Harpoceras sp.
< Mercaticeras sp., Hildoceras sp
[o) = 0m
H | hoelderi
tenuicostatum
BRECLER Bouleiceras sp.
. Radstockiceras sp2_
=]= spinatus 5 Radstockiceras sp. 2, Argutarpites sp ——
= margaritatus
= davoei Radstockiceras sp.2
zZ | jbex 100m
w Radstockiceras sp
= 5
&L | jamesoni AACHENER)
[e4
=)
>23
1
=
0 0m

Abb. 7: Teilprofil des Jura der Quebrada Larga (Abb. 1, Profil 11); Legende zur Gesteinsausbildung

Abb. 10.

Actinastrea sp. h
„Rhynchonella“ sp. sh
„Terebratula“ sp. h
Entolium cf. demissum (PHiLıpps) h
Camptonectes sp. s
Chlamys cf. textoria (SCHLOTH.) h
Weyla sp. sh
Pseudolimea sp. s
Frenguelliella sp. s
Pholadomya sp. s
Pleuromya sp. h
Lithotrochus andinus (MÖRICKE) h
Uptonia sp. h
Über einer 1 m mächtigen Fossilschuttkalkbank folgen
nochmals sandige Schichten (Schicht 3) mit sehr häufig
Weyla, häufig ‚„‚Rhynchonella“, sowie „Terebratula“,
Entolium, Psendolimea, Pholadomya und Radstock-

Iceras.

Bei Schicht 4 sind mehr oder minder gut gebankte Kalke
mit Mesomiltha hnayquimili (Leanza), Cenoceras, Rad-
stockiceras sp. 2 und Atractites aufgeschlossen.

In Schicht 5 kommen in petrographisch ähnlichen Kal-
ken Radstockiceras sp. 2 und Argutarpites vor.

Im Bereich von Schicht 6 und 7 sind feinschichtige bis
schiefrige Kalke mit Pectinula cancellata Leanza aufge-
schlossen, bei Schicht 6 mit einer 10 cm mächtigen Kalk-
bank in der neben P. cancellata Radstockiceras sp. 2 auf-
tritt. In den sandigen Kalkschiefern von Schicht 7 wurde
ein schlecht erhaltenes, weitnabeliges Bouleiceras gefun-
den, das große Ähnlichkeit mit Bouleiceras sp. bei v. Hır-
LEBRANDT (1973, S. 359) besitzt (s. S. 13).

Es folgt eine Serie aus Mergeln mit sandigen Kalkbän-
ken, in den Schichten 8 mit Peronoceras cf. subarmatum,
Peronoceras largaense, Harpoceras sp., Hildaites sp. und
Mercaticeras sp. Diese Serie endet mit ca. 5 m mächtigen,
in sich 40 cm gebankten, sandigen Fossilschuttkalken mit
sandigen Kalkschieferlagen. Unmittelbar ım Hangenden
enthalten mergelige Kalke eine reiche Ammonitenfauna
(Schicht 9):

Peronoceras cf. planiventer (GUEX)

Peronoceras cf. crassicostatum (GUEX)

Collina sp.

Polyplectus sp.

Osperlioceras sp.

Phymatoceras sp. ex gr. P. erbaense (v. HAUER)
Hildoceratidae gen. et sp. indet. (3 Arten)

Direkt im Hangenden dieser Ammonitenfauna folgt
Schicht 10 mit Phymatoceras cf. fabale und Phym. cf.
hlh.

In den hangenden Sandsteinbänken (10 bis 20cm ©), die
mit sandigen Mergeln wechsellagern, kommt Phymatoce-
ras copiapense (MöRrıcke) vor (Schicht 11).

Es folgt eine kleine Steilstufe aus dickbankigen Sand-
steinen mit Geröllen (2 bis 4 mm ®), die von weicheren,
mürben Sandsteinen überlagert werden, im hangenden
Teilmit Gryphaea und Lopha. In der nördlichen Fortset-
zung der Quebrada Larga (Quebrada unmittelbar westlich
der Quebrada San Pedrito) ist diesen Mürbsandsteinen ein
ca. 3 m mächtiger Fossilkalk eingeschaltet, mit sehr häu-
fig Lopha, seltener Entolium und sehr selten Eudmetoce-
ras. Hangend folgt eine 1 m mächtige Bank mit häufig

Eudmetoceras, sowie Gryphaea cf. bilobata (Sow.), Lo-
pha, Chlamys cf.textoria (SCHLOTH.), Eopecten cf. tuber-
culosus (GoLpr.) und Pleuromya sp.

Diese Sandsteinserie wird von grünen Tuffen, Vulkani-
ten und einer Serie aus roten Sandsteinen und Konglome-
raten überlagert.

Abb. 8: Oberster Abschnitt des Juraprofils der Quebrada Noria südlich Salto de la Muerte (700 m SSW
Punkt 3132) (Abb. 1, Profil 12); Legende zur Gesteinsausbildung Abb. 10.

2.11 QUEBRADA NORIA
(Abb. 1, Profil 12; Abb. 8)

Auf der Höhe von Agua del Medio und Salto de la Mu-
erte (Karte 1:100000, Blatt Carrera Pinto) beginnt südlich
der Quebrada Noria bei 2600 m ein Juraprofil, das über
den Punkt 3132 bis 700 m SSW dieses Punktes reicht. Das
Gesamtprofil wurde bei v. HırLesranDT (1973b, Abb. 1)
dargestellt. Abbildung 8 umfaßt nur den hangenden Teil
des Profils.

Das Liegende des Jura bilden mächtige Konglomerate,
die von ebenfalls mächtigen Vulkaniten überlagert wer-
den, die z. T. auch als Mandelsteinlaven ausgebildet sind.

Der tiefste Teil des Juraprofils mit Sandsteinen und
Konglomeraten kann in das untere Sinemurium gestellt
werden. Nach einer 50 cm mächtigen Kalkbank kommen
in den Sandsteinen vereinzelt Weyla, Gryphaea darwini
Forses und eine Gattung und Art der Eotomariinae (Gast-
ropoda) vor, die für den tiefsten Teil des oberen Sinemu-
rium in Chile typisch ist.

Über der Sandsteinserie folgen mergelige Schichten, in
denen Gryphaea tricarinata PrıLri häufig, Brachiopo-
den (Spiriferina, „Rhynchonella“, ‚‚Terebratula‘“) und
Lithotrochus humboldti (v. Buch) selten sind.

Der größte Teil des oberen Sinemurium ist als eine
mächtige Serie aus Sandsteinen und Konglomeraten ent-
wickelt, die wenig Fossilien enthält.

Die Grenze zum unteren Pliensbachium verläuft durch
den obersten Abschnitt dieser Serie, hier fehlen Konglo-
merate. In den Sandsteinbänken sind Steinkerne von
Weyla häufig. Diese Schichten reichen bis Punkt 3132.

Der höchste Teil des Profils ist 700 m SSW Punkt 3132
aufgeschlossen (Abb. 8). Über den Sandsteinen mit Ab-
drücken von Weyla liegt ein 1 m mächtiger, kalkiger
Sandstein mit Schalenexemplaren von Weyla (Schicht 1,
Abb. 8) und darüber nochmals ca. 2 m Sandstein. Es fol-
gen mehr oder minder sandige und fossilschuttreiche
Kalke mit Brachiopoden und Artractites (Schicht 2). Un-

gefähr in der Mitte zur folgenden kleinen Kuppe beginnen
dünnbankige, schiefrige Kalke mit Radstockiceras sp. 2
(Schicht 3). Die Kalkschiefer reichen noch etwas den fol-
genden Hügel hinauf. Im hangendsten Teil der Kalkschie-
fer treten die ersten, schlecht erhaltenen Dactylioceraten
auf. Über ihnen liegt eine Serie aus 10 bis 25 cm mächti-
gen, kalkigen Sandsteinbänken, die mit Mergeln gleicher
Mächtigkeit wechsellagern. Im liegendsten Teil dieser Se-
rie (Schicht 4) sind gut erhaltene Dactylioceraten häufig,
Harpoceraten selten:

Dactylioceras (Orthodactylites) hoelderi n. sp.

Dactylioceras (Orthodactylites) directum (BUCKMAN)
Dactylioceras (? Orthodactylıtes) helianthoides YOKOYAMA
Eleganticeras cf. elegantulum (YOUNG & BIRD)

2.12 QUEBRADA LLARETA
(Abb. 1, Profil 13)

Die Quebrada Llareta ist eine Seitenquebrada der Que-
brada Tolar, die ihrerseits von der Quebrada San Miguel
abzweigt.

Ein Profil wurde auf der linken Talseite, beginnend bei
der Abzweigung von der Quebrada Tolar, aufgenommen.
Der Jura grenzt mit unscharfem Kontakt an Granodiorit.
Im Randbereich treten dunkle Intrusiva auf. Die stark ge-
störten Juraschichten sind zunächst marmorisiert oder in
Hornfels umgewandelt. Porphyritintrusionen sind häu-
fig. Schlecht erhaltene Weyla treten auf. Es folgen dunkle,
geschieferte Kalke bis Kalkschiefer mit selten Radstocki-
ceras. Darüber liegen hellere Mergel- und Kalkschiefer
mit Peronoceras sp. ex gr. P. subarmatum und Harpoce-
ras. In der Profilfortsetzung (nach Osten) sind in einem
Sattelkern nochmals dunkle Kalkschiefer mit Radstocki-
ceras aufgeschlossen und wieder die helleren Mergel- und
Kalkschiefer. Über ihnen liegt eine Kalkbank mit Perono-
ceras cf. P. cf. vortex, Maconiceras sp., Polyplectus sp.
und Phymatoceras sp. Der Jura grenzt im Osten an Por-
phyrite.

Bei Cueva de Mendez ist in der Quebrada San Miguel
auf der linken Talseite zwischen 2 kleinen Seitenquebradas
ein durch Intrusiva begrenztes Juraprofil aufgeschlossen.
Der Jura beginnt mit grauen und grünlichen Feinsandstei-
nen, die zum Hangenden hin etwas kalkiger werden und
nach ca. 50 bis 70 m Mächtigkeit häufig, schlecht erhal-
tene Phymatoceras des oberen Toarcium enthalten. Dar-
über liegen mittel- bis grobkörnige Sandsteine mit häufig,
einer neu zu beschreibenden Gattung und Art der Iso-
gnomonidae (cf. Gervilleioperna), selten Lopha und Pho-
ladomya, sehr selten Bredyia sp. (unteres Aalenium). Die
obersten 10 m der Sandsteine sind wieder etwas feinkör-
niger.

2.13 RIO JORQUERA
(Abb. 1, Profil 14a-c; Abb. 9)

9 km vor La Guardia ist auf der linken Seite des Rio Jor-
quera, bei der Mündung der Quebrada del Carrizo (Ma-
jada del Carrizo) in den Fluß, ein Juraprofil aufgeschlos-

sen, das Schichten des Pliensbachium und unteren Toar-
cium umfaßt.

Der Jura transgrediert mit einer 60 bis 70 cm mächti-
gen, sandig-konglomeratischen Kalkbank (Gerölle bis
4 cm ®) auf rote, schlecht gebankte Tuffe der ? Trias. An
der Unterseite der Kalkbank wurde eine Uptonia gefun-
den. Es folgen 10 bis 40 cm gebankte, knollige, kalkige
Fein- bis Grobsandsteine mit vereinzelt Weyla (Bruch-
stücke), konglomeratische Lagen sind selten. Viele Bänke
werden von Bohrgängen durchzogen, die vorwiegend mit
rotem Sediment ausgefüllt sind. Zum Hangenden hin
werden die Bänke feinkörniger (10 bis 20 cm gebankt).
Die Oberflächen sind häufig von Weyla bedeckt. Im obe-
ren Drittel dieser Serie wurden Bruchstücke von Uptonia
gefunden. Die hangendsten Bänke dieser Serie (Schicht 1)
enthalten häufig Chlamys cf. textoria, Weyla, Plagiosto-
ma, Bryozoen, Andenipora liasica und selten ‚„‚Terebra-
tula“.

Über dieser vorwiegend sandigen Serie liegen 10 bis
20 cm gebankte, mehr oder minder knollige, fossilschutt-

' pacificum
Targaense | Horpmcerasn, Franaceras ei renzi
Peronoceras largaense ‚Pcf. subarmatum
>2 Hildaites cf. levisoni, Dact. (O)directum
> 'hoelderi Nodicoeloceras cf crassoides Form C
©
x
= et. —
= tenuicostatum Dact (Orthod.) sp., Hildaites sp
spinatus Radstockiceras sp
margaritatus Radstockiceras sp
>2
>
a5
©
<
davoei Radstockiceras sp
[a]
[02]
=
wu =
=; Uptonia sp.
a.
Jamesonı Uptonia sp.
Uptonia sp

Abb. 9: Juraprofil bei Majada del Carrizo (Rio Jorquera) (Abb. 1, Profil 14b); Legende zur Gesteinsaus-

bildung Abb. 10.

reiche Kalke, die mit kalkig-mergeligen Schichten wech-
sellagern.

Schicht 2 ist ein Horizont mit häufig ‚‚Rhynchonella“
und ‚‚Terebratula“, sowie selten Modiolus, Cardinia,
Pholadomya cf. corrugata, Lithotrochus andinus und Up-
tonıa.

Die folgende Bank ist reich an „‚Rhynchonella“, ‚,Te-
rebratula“, Ostreiden, Chlamys, Weyla und viel Fossil-
schutt. Im Hangenden dieser Bank werden die mergelig-
kalkigen Lagen etwas mächtiger, ihnen sind noch 3 Bänke
(15 bis 30 cm ®) mit reichlich Fossilien eingelagert. In ei-
ner Bank ist eine flache Einzelkoralle (Montlivaltia), an
der Oberfläche einer weiteren Bank Weyla häufig. Es fol-
gen schiefrig-sandige Mergel bis Sandsteine und eine
60 cm mächtige Sandsteinbank, die von ebenfalls stark
sandigen Mergeln mit „‚Rhynchonella“, ‚‚Terebratula“
und Weyla überlagert wird. Diese gehen wieder in kalkige
Mergel mit knolligen Kalkbänken über. Bei Schicht 3 sind
diese sehr fossilreich und enthalten:

Montlivaltia sp. h
„Rhynchonella“ sp. h
‚„‚Terebratula“ sp. sh
Modiolus sp.
Gervilleioperna turgida LEANZA ss
Weyla sp.
Plagiostoma sp. s
Cardinia cf. andium GIEBEL s
Neocrassina Sp. ss
Pholadomya cf. corrugata K. & DUNKER h
Homomya rotundocaudata (LEANZA) ss
Radstockiceras sp. ss
Die Schichtfolge geht mit petrographisch ähnlichen Se-

dimenten weiter, die z. T. ebenfalls sehr fossilreich sind.

Bei Schicht 4 wurden gefunden:
Actinastrea sp. ss
„Rhynchonella“ sp. h
„Terebratula“ sp. h
Modiolus sp. ss
Entolium cf. demissum (PHILIPPS) ss
Mesomiltha huayquimili (LEANZA) s
Pholadomya cf. plagemanni MÖRICKE s
Pholadomya cf. corrugata K. & DUNKER s

Es folgt eine Wechsellagerung von Mergeln mit gut ge-
bankten, weniger fossilschuttreichen Kalken (10 bis20 cm
®), die Querschnitte von Radstockiceras enthalten. Sie
werden von zunächst bis 40 cm mächtigen, mehr oder
minder feinsandigen und gut gebankten Kalken überla-
gert, in denen selten Querschnitte von Radstockiceras
vorkommen. Einzelne Bänke sind reich an Fossilschutt.
Zum Hangenden hin enthalten die Bänke zunehmend
Sandsteinschnüre und Sandsteinlinsen, sind zum Teil
knollig ausgebildet, und die Oberflächen der Bänke kön-
nen wellig sein. Im hangenden Teil werden die Bänke bis
60 cm mächtig, sind zumeist reich an Fossilschutt und in
manchen Bänken kommt Weyla häufig vor.

In der Profilfortsetzung werden die Bänke wieder ge-
ringermächtig, und sie werden von einer Serie aus Mergeln
mit gut gebankten Kalken (bis 20 cm ©) mit wenig Fossil-
schutt überlagert. Schicht 5 enthält die ersten, sehr

schlecht erhaltenen Dactylioceras (Orthodactylites) und
Hildaites.

Schicht 6 ist die erste rostbraun anwitternde Kalkbank
einer Serie petrographisch ähnlich ausgebildeter Kalke
(Bänke bis 30 cm mächtig), die mit Mergeln wechsella-
gern. Die letzte dieser Kalkbänke (40 cm ©) (Schicht 7) ist
reich an Propeamussinm und es kommen Dactylioceras
(Orthodactylites) directum, Dact. (O.) cf. directum, No-
dicoeloceras cf. crassum Form C, Polyplectus sp., Harpo-
ceras cf. falcifer (stark involut) und ein großwüchsiges
(bis über 30 cm ®) Hildaites vor, das mit dem von SCHLE-
GELMILCH (1976; Taf. 44, Fig. 3) abgebildeten Aildaites
cf. levisoni große Ähnlichkeit aufweist.

Es folgt eine Wechsellagerung von knolligen Kalken mit
Mergeln. Etwa 25 cm über der Bank mit Dactylioceras
(O.) directum kommen Peronoceras cf. subarmatum, P.
largaense (Bruchstücke) und Harpoceras sp. vor
(Schicht 7a).

Das Hangende bilden Mergel mit geringmächtigen
Kalkbänken.

In Schicht 8 kommen sehr häufig ‚‚Rhynchonella“ und
„Terebratula“ vor, sehr selten sind Peronoceras cf. renzi
und Harpoceras sp. Mit diesen Schichten endet das Profil
Majada del Carrizo am Rio Jorquera.

1,3 km talabwärts der Quebrada del Carrizo wurde auf
der rechten Talseite des Rio Jorquera bei Vegas de Chanar
ein weiteres Profil aufgenommen. Der Jurastreifen dieses
Profils quert weitere 700 m talabwärts das Tal und ist nun
auf der linken Talseite aufgeschlossen.

Der Jura transgrediert bei diesem Jurastreifen auf
dunkle Mandelsteinlaven. Die basalen Sandsteine enthal-
ten keine Bohrgänge. Das Pliensbachium (+ ? obere Si-
nemurium) ist mächtiger (ca. 200 m) als bei der Quebrada
del Carrizo (ca. 160 m), die Schichtfolge sonst ähnlich
ausgebildet. Auch das Toarcium liegt in der gleichen Fa-
zies vor, im tiefsten Toarcium mit schlecht erhaltenen, °
flachgepreßten Dactylioceraten und Harpoceraten, han-
gend die rostbraun anwitternden Kalke und die diese Serie
abschließende Kalkbank mit Propeamussium und selten
Peronoceras und Harpoceras (schlecht erhalten). Es fol-
gen die mehr mergeligen Schichten mit ‚‚Rhynchonella“
und „Terebratula“ (= Schicht 8 der Quebrada del Carri-
zo). Das untere Toarcium schließt mit sandig-knolligen
Fossilschuttkalkbänken ab. Besonders eine der hangend-
sten Bänke istreich an Ammoniten. Diese Bank ist auf der
linken Talseite, 500 m westlich der Basis des Jura, aufge-
schlossen und enthält:

„Terebratula“ sp. h

Plagiostoma sp. s

Myophorella sp. s

Pholadomya cf. corrugata K. & DUNKER h
Pholadomya cf. plagemanni MÖRICKE h
Peronoceras sp. cf. P. cf. vortex (SIMPSON)
Peronoceras cf. bolitoense n. sp.

Collina chilensis n. sp.

Harpoceras cf. subexaratum (BON.)
Hildoceratidae gen. et sp. indet (glatte Art)

Über diesen Fossilschuttkalken liegen gut gebankte
Kalke (bis 30 cm ©) mit Phymatoceras, die in Kalke mit
zunehmendem Gehalt an Fossilschutt übergehen und auf
der linken Talseite tektonisch stark verdrückte Pleydellia
(Walkericeras) enthalten. Von der rechten Talseite stammt
eine relativ gut erhaltene Pleydellia (Walkericeras) ct. lo-
tharingica und Hammatoceras sp.

Es folgt eine Serie dickbankiger (bis 2 m ©), zunächst
stark sandiger Kalke, die auf der linken Talseite stark ge-
stört sind. Diese z. T. fossilschuttreichen Kalke werden
auf der rechten Talseite ca. 50 m mächtig, und sie sind in
das Aalenium zu stellen.

Über einem bis 3 m mächtigen Andesit liegt mit sedi-
mentärem Kontakt eine Serie (ca. 25 m mächtig) von ro-
ten, grünlichen und grauen Mürbsandsteinen und darüber
sandigen Kalken und Fossilkalken mit Ostreiden. Diese
Serie gehört wahrscheinlich bereits dem Callovium an.
Das Callovium wird von einer mächtigen, roten Sand-
steinserie überlagert.

2,5 km westlich La Guardia wurde oberhalb Las Ban-
deritas (Rio Jorquera), zwischen 3290 m (Jurabasis) und
3450 m Gipfel, ein weiteres Profil aufgenommen.

Das untere Pliensbachium ist sehr viel geringer mächtig
(ca. 20 m) als bei Majada del Carrızo. Den vorwiegend
sandigen Schichten sind im mittleren Teil nach einem 2 m
mächtigen Konglomerat auch Fossilschuttkalke einge-
schaltet.

Die dickbankigen, sandigen Kalke des oberen Pliensba-
chium sind etwa 40 m mächtig, stärker sandig als bei Ma-
jada del Carrizo, enthalten großwüchsige ‚,Terebratula“
im mittleren Teil und Weyla in den obersten, dickbanki-
gen Kalksandsteinen. Es folgen 10 bis 50 cm gebankte
Kalke (ca. 10 m mächtig) mit Querschnitten von Radstok-
kiceras, die in 10 bis20 cm gebankte, knollige Kalke über-
gehen. Über ihnen liegen die braun anwitternden, fein-
sandigen Kalke mit Weyla sp., Dactylioceras (Orthodac-
tylites) und Hildaites (oder Harpoceratoides). Das Toar-
cium ist in ähnlicher Mächtigkeit und Fazies wie bei Ma-
jada del Carrizo ausgebildet. Die bräunlich anwitternden
Kalke enden mit einer kleinen, 3 m hohen Steilstufe, die
von bis 1 m mächtigen Fossilschuttkalkbänken gebildet
wird, ın denen Propeamussium häufig und Chlamys sel-
ten sind. Außerdem kommen Peronoceras sp. ex gr.
P. subarmatum und Harpoceras vor. Hangend folgen
Mergel mit geringmächtigen Kalkbänken, im oberen Teil
mit häufig ‚‚Rhynchonella“ und ‚Terebratula“, selten
Modiolus und Harpoceras (entspricht Schicht 8 bei Ma-
jada del Carrizo).

Diese mergelige Serie wird von dickbankigen, fossil-
schuttreichen Knollenkalken (ca. 5 m mächtig) überla-
gert, die eine kleine Steilstufe bilden. In den unteren 2 m
sind schlecht erhaltene Peronoceras cf. bolitoense und
Harpoceras sp. vorhanden. Aus der gleichen Schicht
stammt ein großwüchsiges Exemplar einer Leukadiella
cf. gallitellii Pınna. Es ist dies der erste Nachweis dieser

Gattung in Südamerika. Aus diesem Schichtbereich (oder
nächsten Fossilschicht) muß das von Mörıck£ (1894,
Taf. 2, Fig. 6) beschriebene ‚‚Deroceras aff. Davoei
Sow.“ (= Peronoceras moerickei n. sp.) von La Guardia
stammen.

Etwa 1 m hangend der Knollenkalke liegt eine 20 cm
mächtige, brüchige, bituminöse Kalkbank mit Peronoce-
ras sp. (Bruchstück), Catacoeloceras sp. und Hildocerati-
dae gen. et sp. indet. (3 Arten). Direkt hangend folgt eine
weitere, 10 cm mächtige, brüchige Kalkbank mit Phyma-
toceras cf. fabale.

Die weitere Schichtfolge besteht aus 10 bis 20 cm ge-
bankten, splittrigen Kalken mit schlecht erhaltenen Am-
moniten, zuerst noch mit Phymatoceras, dann Phlyseo-
grammoceras. Unterhalb des Grates bei 3435 m stehen
dickbankige Fossilkalke mit Gryphaea und selten Lopha
an. Am Grat ist eine 10 cm mächtige Schicht mit häufig
Neocrassina cf. andium (GOTTSCHE), sowie Lopha, Myo-
phorella und Pleydellia (Walkericeras) cf. lotharingica
des obersten Toarcıum aufgeschlossen.

Die hangenden, ca. 2 m mächtigen, knollig-kalkig-san-
digen Schichten enthalten noch schlecht erhaltene Pley-
dellia (Walkericeras). In dem folgenden 2 m mächtigen
Fossilkalk tritt Bredyia sp. des basalen Aalenium auf. In
diesem Fossilkalk ist eine neue Gattung und Art der Iso-
gnomonidae (cf. Gervilleioperna) häufig, daneben kom-
men Chlamys, Ctenostreon und ‚‚Terebratula“ vor.

In den anschließenden Kalken (ca. 2 m mächtig) sind
ein großwüchsiges Entolium und Chlamys häufig, Bre-
dyia sehr selten. Darüber liegen 3 bis 1 m mächtige Kalk-
bänke mit Gryphaea und sehr selten Bruchstücken von
? Eudmetoceras.

Über diesen Kalken des Aalenium folgen noch gering-
mächtige, sandige und kalkige, z. T. rötliche Schichten
des Callovium und über diesen eine mächtige, rote Sand-
steinserie.

2.14 QUEBRADA CALQUIS
(Abb. 1, Profil 15)

Die Quebrada Calquis mündet 3 km nördlich der Ha-
cienda Amolanas in den Rio Copiapö. Auf dem Bergrük-
ken, der die untere Quebrada Calquis südlich begrenzt,
wurde ein Juraprofil aufgenommen. Die Schichten fallen
vorwiegend steil nach Westen ein, Mehrere durch Störun-
gen und enge Falten bedingte Schichtverdoppelungen sind
vorhanden.

Mergelige Kalke mit häufig Weyla, selten Radstockice-
ras behrendseni und Atractites können in den oberen Teil
des unteren Pliensbachium (+ ibex-Zone) gestellt wer-
den. Graue Mergel mit häufig Nuculana (doppelklappig)
und plattige, mehr oder minder mergelige Sandsteine mit
flachgepreßten Radstockiceras gehören dem oberen
Pliensbachhum an. Im Hangenden folgen kalkreiche

Schichten. Über ihnen liegt eine etwa 100m mächtige Se-
rie, die aus einer Wechsellagerung von roten Mergeln mit
mehr oder minder sandigen Mergelkalken besteht. Im
hangenden Teil enthalten die rotbraunen Sandsteine häu-
fig Propeamussinm, weniger häufig ‚‚Rhynchonella“, sel-
ten Modiolus, Plagiostoma, Mesomiltha, sowie Dactylio-
ceras (Orthodactylites) cf. hoelderi, Nodicoeloceras cf.
crassoides Form A, Hildaites und Polyplectus. Diese Se-
rie muß dem tieferen Teil des unteren Toarcium (hoelde-
ri-zone) zugeordnet werden.

Am NW-Fuß des Bergrückens grenzen mit einer Stö-
rung Sandsteine an Rotschichten mit ebenfalls rötlichen
Fein- bis Grobsandsteinen, in denen schlecht erhaltene
Bruchstücke von Peronoceras ex gr. P. subarmatum und
Harpoceras vorkommen. Diese Fauna ist etwas jünger als
die mit Dactylioceras (Orthod.) cf. hoelderi.

2.15 RIO MANFLAS, PROFIL ZWISCHEN DEM
FLUSS
UND DEM PORTEZUELO EL PADRE
(Abb. 1, Profil 16)

Vom Rio Manflas (Basis) wurde zum Portezuelo EI
Padre (Übergang zur Quebrada de la Iglesia) ein Juraprofil
aufgenommen, das eine Mächtigkeit von 1700 m erreicht.
Die Profilaufnahme wurde dort begonnen, wo die Basıs-
schichten des Jura den Fluß kreuzen. Das Liegende des
Jura bilden grünliche Tuffe. Der Jura beginnt mit 4 bis
5 m mächtigen, 30 bis 60 cm gebankten Fossilschuttkal-
ken, die in mehr oder weniger kalkige, 20 bis 40 cm ge-
bankte Sandsteine (z. T. mit Fossilschutt) übergehen.
Etwa 60 m über der Basis beginnt eine ca. 5 m mächtige
Serie von Kalken mit mergelig-kalkigen Zwischenlagen, in
denen Gryphaea darwini Forses und Lithotrochus hum-
boldti (v. Buch) häufig sind. Selten kommen vor ‚‚Rhyn-
chonella“, Weyla, Entolium (mehr in den Kalkbänken)
und eine für den tiefsten Teil des oberen Sinemurium typi-
sche Gattung und Art der Eotomariinae. Es folgen Mergel
mit kalkigen, z. T. sandigen Bänken und Fossilschutt,
etwa 130 m über der Basis mit einer weiteren Fossil-
schicht: Spiriferina, ‚‚Rhynchonella“, Gryphaea tricari-
nata, Plicatula, Jaworskiella gryphitica, Cardinia, Litho-
trochus humboldti u. L. andinus. Diese sandig-mergeli-
gen Schichten gehen über in eine sehr mächtige Serie (über
600 m) aus dunkelgrauen, dm-gebankten Kalken, die mit
dunkelgrauen Mergeln wechsellagern. Abschnittsweise
überwiegen die Kalkbänke, dann wieder die Mergel. Fos-
silien sind selten (Plagiostoma, Mesomiltha, Cardinia). Im
hangendsten Abschnitt wurde ein Dactylioceras (Ortho-
dactylites) tenuicostatum chilense gefunden. Diese kal-
kig-mergelige Serie umfaßt also zumindest einen Teil des
oberen Sinemurium, das Pliensbachium und reicht bis in
das basale Toarcium. Sie geht in eine 50 bis 60 m mächtige,
vorwiegend bräunlich verwitternde, kalkige Sandsteinse-
rie über mit selten kalkigen Bänken. Vereinzelt kommen
„Rhbynchonella“ und ‚„Terebratula“ vor. In den obersten

Bänken ist Liostrea häufig. Außerdem wurden in dieser
Serie ein kleines Bruchstück eines Dactylioceras (Ortho-
dactylites) und Plagiostoma gefunden.

Es folgen 60 bis 70 m mächtige, gelblich-braun verwit-
ternde, z. T. kalkige Mergel und anschließend wieder 70
bis 80 m mächtige, dm-gebankte, kalkige Sandsteine, die
im tieferen Teil mit sandig-mergeligen Schichten wechsel-
lagern, in denen vereinzelt ‚‚Terebratula“ und Weyla
vorkommen. Den Abschluß dieser Serie bildet eine ca.
10 m hohe Steilstufe aus Kalksandsteinen.

Über dieser Steilstufe liegen wieder gelblich-braun ver-
witternde, z. T. kalkige Mergel mit Peronoceras bolitoen-
se, P. sp., Collina cf. chilensis, Polyplectus sp. und Hildo-
ceratidae gen. et sp. indet. (glatte Art) im basalen Teil.
Nach etwa 100 m Mächtigkeit werden die Kalkmergel röt-
lich und enthalten Phymatoceras copiapense. Zum Han-
genden hin nimmt allmählich der Sandgehalt der Mergel
zu. Aus diesen Schichten stammt ein Phlyseogrammoceras
tennicostatum. Diese mergelig-sandige Serie endet mit ei-
ner ca. 5 m mächtigen, roten Grobsandsteinbank mit ein-
zelnen Geröllen (bis 0,5 cm ®) und sehr selten Bredyia
(basales Aalenium). Es folgen etwa 4 m mächtige graue
Kalke mit Eudmetoceras, die in feinschichtige, etwa 4 m
mächtige, z. T. rötliche Mergel übergehen. Über ihnen
liegen rote Mergelkalke, die zum Hangenden hin sandiger
werden und Sonninien und Stephanoceraten der ‚‚sower-
byi“- und der sauzei-Zone (unteres Bajocium) enthalten.
Es sind dies die jüngsten im Bereich des Portezuelo El
Padre aufgeschlossenen Schichten.

2.16 RIO PULIDO
(Abb. 1, Profil 17; Abb. 10)

Bei Iglesia Colorada wurde auf der linken Talseite des
Rio Pulido in einer kleinen Seitenquebrada ein Profil auf-
genommen. Der Jura grenzt mit einer schlecht aufge-
schlossenen Störung an Granit. Der Jura beginnt mit
dickbankigen, mehr oder minder sandigen Kalken, die an
Fossilien Weyla und Einzelkorallen enthalten (Schich-
ten 1). Es folgen stark gestörte, dickbankige Sandsteine.
Darüber liegen dickbankige Kalke mit massenhaft Gry-
phaea (kleinwüchsig) (Schichten 2) und gebankte Fossil-
schuttkalke mit geringmächtigen Kalkmergelzwischenla-
gen und Weyla (Schichten 3). Diese Schichten gehen über
in eine Serie 5 bis 20 cm gebankter, vorwiegend dichter
Kalke mit ebensomächtigen (oder mehr) Kalkmergelzwi-
schenlagen. Vereinzelt tritt Weyla auf. Über dieser Serie
liegen feinschichtige, mergelig-sandig-schiefrige Schich-
ten mit flachgepreßten Radstockiceras. Es folgen graue
Mergel mit selten Kalkbänken, dann vorwiegend 10 bis
20cm gebankte, rostbraun anwitternde, feinsandige
Kalke mit sandigen Mergelzwischenlagen. Sie gehen in
dünnbankige Kalke (5 bis 15 cm 2) über, die mit Mergeln
wechsellagern. Propeamussium ist in diesen Schichten
häufig.

Anschließend ist eine Serie mehr oder minder sandiger
und fossilschuttreicher Kalke mit Gryphaea und ‚‚Rhyn-
chonella‘“ aufgeschlossen. Die Bänke sind 20 bis 50 cm
mächtig. Im mittleren Teil sind die sandig-mergeligen
Zwischenlagen mächtiger als die Kalkbänke. In der han-
gendsten Bank sind Ammoniten häufig: Peronoceras cf.
bolitoense n.sp., Collina chilensis n.sp., Harpoceras cf.
subexaratum, Hildoceratidae gen. et sp. indet. (glatte
Art).

Die Fortsetzung des Profils ist schlecht aufgeschlossen.
Es wiegen Mergel vor. Nach ca. 80 m Mächtigkeit kom-
men in einer 30 bis50 cm mächtigen Kalkbank Pleydellia
(Walkericeras) cf. lotharingica (Branco) und Dumortie-
ria pusilla Jaw. vor. Über dieser Bank werden die den
Mergeln eingelagerten Kalkbänke zunehmend mächtiger
und die Bänke allmählich knollig. Die Serie endet mit ge-
bankten Kalken, in denen vereinzelt Brachiopoden und
Pelcypoden vorkommen. Aus diesen Schichten stammt
ein Hammatoceras sp.

Den Abschluß des Juraprofils bildet eine Serie häufig
dickbankiger und fossilschuttreicher, z. T. sandiger Kal-
ke, die mit weicheren, sandig-mergelig-kalkigen Schich-
ten wechsellagern, die z. T. ebenfalls sehr fossilreich sind.
An der Basis kommt Bredyıa vor, immittleren Teil Spae-
rocoeloceras und im hangenden Abschnitt Eudmetoce-
ras.

Außerdem wurden in dieser Serie gefunden:
„Rhynchonella“ sp.
„Terebratula“ sp. (großwüchsig)
Gryphaea sp.
Lopha sp.
Modiolus sp.
Isognomonidae nov. gen. nov. sp. (cf. Gervilleioperna )
Entolium cf. demissum (PHILIPPS)
Chlamys cf. textoria (SCHLOTH.)
Eopecten cf. tuberculosus (GOLDF.)
Trigonia sp.
Mesomiltha cf. bellona (D’ORB.)
Mesomiltha sp. (großwüchsig)
Neocrassina andium (GOTTSCHE)
Trigonastarte (?) steinmanni (MÖRICKE)
Pleuromya sp.
Cercomya sp.

Der Jura grenzt an einen Andesit, und über diesem liegt
eine Serie roter Sandsteine und Konglomerate.

2.17 RIO MANFLAS
(Abb. 1, Profile 18 und 19; Abb. 10)

Zwischen der Quebrada del Medio und der Quebrada
Berrocal beginnt am Rio Manflas ein Jurastreifen, der
15 km lang ist und bis Juntas del Toro reicht. Südlich Los
Graneros befinden sich die Juraschichten vollständig auf
der rechten Talseite. In diesem Jurastreifen wurden 3 Pro-
file aufgenommen. Das nördlichste Profil liegt 2,5 km
südlich Los Graneros, zwischen dem Rio Manflas und
dem Cerro Salto del Toro. Das zweite Profil wurde 2 km

nördlich Juntas del Tolar und das dritte Profil bei Juntas
del Toro, am Beginn des Rio del Toro, vermessen. Von
Norden nach Süden nımmt die Mächtigkeit des Jura all-
mählich ab (Abb. 10). Bestimmbare Dactylioceraten
wurden in den Profilen Cerro Salto del Toro und Juntas

del Toro gefunden.

2.17.1 Profil Salto del Toro
(Abb. 1, Profil 18)

Auf feinschichtige Tuffe transgrediert eine 1,0 bis 1,3 m
mächtige Aufarbeitungslage mit Porphyritgeröllen (bis
30 cm ®). Darüber liegt eine 40 bis 50 cm mächtige Kalk-
bank, die sich fast vollständig aus einer kleinwüchsigen
Gryphaea zusammensetzt. Bruchstücke von Weyla sind
selten. Direkt hangend folgt eine 20 bis 30 cm mächtige
Kalkbank mit ‚„‚Rhynchonella““ an der Basıs. Darüber lie-
gen Kalke mit vereinzelt Gryphaea, die zum Hangenden
hin seltener wird. Aus diesem Bereich (Schicht 2,
Abb. 10) stammt ein Epideroceras des obersten Sinemu-
rium. Die Kalke werden knollig und bei Schicht 3 fehlen
auf 2 bis3 m mergelige Zwischenlagen. In diesen schlecht
gebankten Kalken tritt Uptonia und selten Weyla auf.
Nach einem schichtparallel intrudierten Porphyrit sind
wieder gut gebankte (15 bis 30 cm ®) Kalke mit selten
Weyla vorhanden. Bei Schicht 4 treten Fossilschuttkalke
mit Gryphaea (kleinwüchsig), Weyla, Pholadomya_ cf.
corrugata und Pleuromya auf. In den gut gebankten Kal-
ken der Schichten 4a und 5 wurden Cenoceras und Rad-
stockiceras gefunden. Bei Schicht 6 sind 2 bis 3 m mächti-
ge, feinschichtig-schiefrige, kalkige Sandsteine bis fein-
sandige Kalke mit Fossilschutt, Pectinula cancellata und
Radstockiceras aufgeschlossen.

Über diesen Pectinulaschiefern liegen wieder Mergel
(bis 1,5 m mächtig) mit einzelnen, dichten, 10 bis 30 cm
gebankten Kalken. Zum Hangenden hin werden die Mer-
gellagen geringermächtig und die Kalkbänke häufiger. In
dieser Serie wurde im Bereich von Schicht 7 Dactylioceras
(Orthodactylites) tennicostatum chilense, Dactylioceras
(? Orthodactylites) cf. helianthoides und Bruchstücke
nicht näher bestimmbarer Hildoceratidae gefunden. Am-
moniten sind selten und zumeist schlecht erhalten. Das
Dact. (Orthod.) tennicostatum chilense stammt wahr-
scheinlich aus etwas tieferen Schichten als die übrigen
Ammoniten. Die Serie geht in gut gebankte Sandsteine mit
Mergellagen über, die ‚‚Rhynchonella“, ‚‚Terebratula“
und Weyla enthalten (Schicht 8). Es folgt eine Steilstufe
aus bräunlich verwitternden Sandsteinen. Im mittleren
Teil ist ein 2 m mächtiger Horizont vorhanden, in dem
Querschnitte von Weyla häufig sind. Auf der Oberfläche
der obersten Bank dieser Sandsteinserie kommen groß-
wüchsige Peronoceras cf. bolitoense vor (Schicht 9). In
den unmittelbar hangenden, feinschichtigen, sandigen
Kalken treten schlecht erhaltene Phymatoceras auf.

Es folgen vorwiegend dunkle Mergel mit einzelnen
Kalkbänken. Bruchstücke von Phymatoceras copiapense

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und ‚‚Terebratula“ sind häufig, Modiolus und Pleuro-
mya selten. Zum Hangenden hin werden die Kalke zu-
nehmend sandig. In den Bänken sind wulstige Sandstein-
lagen vorhanden. Es schließt eine Serie dickbankiger,
grob- bis mittelkörniger, kalkiger Sandsteine mit viel Fos-
silschutt an. Im tiefsten Teil kommt Pleydellia, etwas hö-
her Bredyia vor. Pelecypoden sind häufig. In den Schich-
ten 12 kommen neben (selten) Ammoniten vor:
‚„Terebratula“ sp.

Gryphaea sp.

Grammatodon sp. (großwüchsig)

Eopecten cf. tuberculosus (GOLDF.)

Plagiostoma sp.

Trigonia sp.

Isognomonidae nov. gen. nov. sp. (cf. Gervilleioperna )
Stomechinus andinus (PHILIPPI)

Die hangendste Bank (1 m mächtig) (Schicht 13) dieser
Sandsteinserie ist erfüllt von Gryphaea, außerdem kom-
men „Rhynchonella“, ‚‚Terebratula“ und Lopha vor.
Direkt im Liegenden dieser Bank tritt Eudmetoceras auf.
1 bis 2 m mächtige, dunkle, dichte Kalke mit Bositra bil-
den den Abschluß des Jura und grenzen gegen einen An-
desit, der mit stratigraphischem Kontakt von roten Sand-
steinen und Konglomeraten überlagert wird.

2.17.2 Profil Juntas del Toro (Rio del Toro)
(Abb. 1, Profil 19)

Das Profil bei Juntas del Toro stimmt petrographisch
weitgehend mit dem 2 km nördlich Juntas del Tolar über-
ein.

Der Jura transgrediert mit einer Brekzie oder Konglo-
merat auf Tuffe der ? Trias. Darüber liegen mehr oder
minder sandige, knollige Kalke (bis 1m ®) mit Weyla
und doppelklappigen, desmodonten Muscheln (Phola-
domya, Homomya) (Schicht 1, Profil N Juntas del To-
lar). Es folgen mergelige Kalke bis Kalkmergel im Rhyth-
mus von 5 bis 20 cm mit häufig ‚‚Rhynchonella“, „‚Tere-
bratula“ und Gryphaea, weniger häufig Weyla
(Schicht 2, Profil N Juntas del Tolar; Schichten 1 Rio del
Toro). Diese fossilreichen Schichten enden mit einer
zweigeteilten, kleinen Steilstufe aus 50 cm bis 1 m ge-
bankten Kalken mit ‚‚Terebratula“, Gryphaea und
Weyla im liegenden Teil, mergeligen Kalken mit häufig
„Terebratula“, seltener ‚„Rhynchonella“ im mittleren
Teil (Schicht 2 Rio del Toro) und mehrere Meter mächti-
gen, z. T. etwas sandigen, häufig schlecht gebankten Kal-
ken mit geringmächtigen Mergelfugen im hangenden Teil.
In diesen knolligen Kalken sind Bohrgänge und Weyla
häufig. Uptonia kommt in mehreren Bänken vor, außer-
dem ‚‚Terebratula“, Pholadomya cf. corrugata und
Pleuromya (Schicht 3, Profil N Juntas del Tolar; Schicht
3 Rio del Toro). Am Ende der Steilstufe wurde in
Schicht 4 (Rio del Toro) ‚„Rhynchonella“, ‚‚Terebratu-
la“, Lopha longistriata (Jaw.), Myoconcha nenquena Lr-
ANZA und Homomya neuquena Leanza gefunden. Über

der Steilstufe folgt eine Wechsellagerung von Fossil-
schuttkalken mit Mergellagen und häufig Weyla. Die Fos-
silschuttkalke werden zum Hangenden hin durch gut ge-
bankte, dichte Kalke (10 bis30 cm ©) ersetzt. Diese Serie
endet mit 1,5 bis 2 m mächtigen, feinschichtig-schiefri-
gen, z. T. sandigen Kalkmergeln, in denen Pectinula can-
cellata sehr häufig ist. Beim Profil Rio del Toro ist in diese
Pectinulaschiefer schichtparallel ein Porphyrit intrudiert.
Im Liegenden des Porphyrit (Schicht 5) kommt Radstok-
kiceras vor und über ihm (Schicht 6) stark verdrückte
Dactylioceras (Orthodactylites) und ein schlecht erhalte-
ner, weitnabeliger Ammonit, der sich noch am ehesten mit
Bouleiceras sp. bei v. HırLesranpt (1973a) vergleichen

läßt (s. $. 13).

Über den Pectinulaschiefern liegen wieder gut gebankte
(10 bis 20 cm ©) Kalke, die mit Mergeln wechsellagern.
Zum Hangenden hin werden die Bänke allmählich sandig
und mächtiger, die Mergellagen geringermächtig und die
Serie geht in dickbankige Kalksandsteine über, denen im
mittleren Teil einige Bänke mit sehr häufig Weyla und
Brachiopoden eingeschaltet sind. Die hangendste Bank
dieser Serie ist bei Profil Rio del Toro (Schicht 7) sehr fos-
silreich und enthält folgende Fauna:

„Rhynchonella“ sp. h
‚„‚Terebratula“ sp. h

Gryphaea sp. s

Entolium cf. demissum (PHiLipps) s
Myophorella sp. s

Neocrassina cf. aureliae FERUGLIO h
Neocrassina sp. S

Pholadomya cf. fidicnla SOW. s
Eucyclus sp. ss

Zygopleura cf. quinetta (PIETTE) s
Peronoceras cf. bolitoense n. sp.
Collina chilensis n. sp.

Harpoceras cf. subexaratum (BON.)
Phymatoceras sp.

Hildoceratidae gen. et sp. indet. (2 Arten)

Direkt hangend folgen eine Bank (Schicht 8) mit Phy-
matoceras cf. fabale und 1,0 bis 1,5 m mächtige, gelbliche
Mergel mit dünnbankigen, kalkigen Feinsandsteinen.

In der anschließenden Mergelserie werden im Han-
gendteil die Kalkbänke häufiger, und die Serie endet mit
sandigen, knolligen Kalken mit geringmächtigen Mergel-
zwischenlagen, die reich an desmodonten Muscheln (Pho-
ladomya cf. fidicula) sind. Im hangenden Teil der Mergel-
serie ıst Phymatoceras copiapense häufig, darüber tritt
Phlyseogrammoceras auf, und in den sandigen, knolligen
Kalken kommt Pleydellia (Walkericeras) cf. lotharingica,
P. (W.) cf. flnitans und Dumortieria cf. pusılla vor.

Die folgende Steilstufe besteht aus dickbankigen Sand-
steinen mit viel Fossilschutt. An der Basis kommen noch
Pleydellia (Walkericeras) und Dumortieria vor (Schicht 6
N Juntas del Tolar; Schicht 10 Rio del Toro). Dann wer-
den die kalkigen Sandsteine allmählich rötlich. Pelecypo-
den (Eopecten cf. tuberculosus, Ctenostreon pectinifor-
mis, Pholadomya cf. plagemanni, Pleuromya sp.) sind
häufig, Querschnitte von großen Ammoniten (? Eudme-

toceras) selten (Schichten 8 N Juntas del Tolar; Schicht 12
Rio del Toro). Der Jura endet mit nochmals grauen
Grobsandsteinen, die an Andesit grenzen.

2.18 EL TRÄNSITO
(Abb. 1, Profil 20 und 21; Abb. 11)

Nördlich (Quebrada Chanchoquin/La Totora), östlich
(Quebrada Plaza) und südlich El Tränsito (Quebrada Pin-
te) wurden mehrere Juraprofile aufgenommen und bei v.
Hırıesranpr (1973b, Abb. 2) dargestellt. Artlich be-
stimmbare Dactylioceratidae wurden bei den abgebildeten
Profilen nur in dem zweiten (geringermächtigen) mit
Quebrada La Totora bezeichneten Profil (Abb. 1, Profil
20) gefunden. Das mächtigere, der beiden mit Quebrada
La Totora bezeichneten Profile bei v. HiLLEBRANDT
(1973 b, Abb. 2), wurde in dem Jurastreifen zwischen der
Quebrada Chanchoquin und der Quebrada Acevedo
(Blatt El Tränsito) vermessen.

Weitere Dactylioceratidae stammen aus Schichten, die
im Liegenden des Steinbruchs (Plicatostylus-Kalke) an der
Vereinigung der Quebrada Chanchoquin mit der Que-
brada Paitepen aufgeschlossen sind. Das Profil wurde bei
v. HıLıesranpr (1973a, $. 353) beschrieben.

2.18.1 Profil südlich Quebrada El Corral
(Abb. 1, Profil 20)

Südlich der Quebrada EI Corral (Seitenquebrada der
Quebrada La Totora) (Karte 1:50000, Blatt Lagunillas),
zwischen dieser und Punkt 2360 (Blatt Conay) wurde ein
Juraprofil aufgenommen.

Die Transgression des Jura erfolgt mit einem 20 cm
mächtigen Fossilschuttsandstein auf Vulkanite der
? Trias. Die anschließenden Feinsandsteine enthalten sel-
ten ‚‚Terebratula“ (einklappig) und gehen über in
Mürbsandsteine mit sandigen Mergeln. Die obersten
Bänke sind kalkig und führen neben Fossilschutt schlecht
erhaltene ‚„‚Terebratula“ und Weyla. In der Quebrada
Chanchoquin kommen in diesen basalen Sandsteinen vor:
Entolium sp. h
Jaworskiella gryphitica (MOR.) h
Pholadomya cf. plagemanni MÖRICKE h
Pleuromya sp. h
Eotomariinae gen. et sp. indet. s
Epophioceras sp. ss

Die Fauna kann in das untere Ober-Sinemurium einge-
stuft werden. Über dieser basalen Sandsteinserie folgt eine
mehr oder minder sandige Mergelserie, der im mittleren
Teil zwei 30 und 60 cm mächtige Fossilschuttkalksand-
steine mit Gryphaea tricarinata Pririrı, Weyla und
„‚Terebratula“ eingeschaltet sind. Im oberen Teil treten
einzelne, 20 bis 50 cm mächtige Kalk- und Sandstein-
bänke auf.

Die Mergelserie wird von einer Serie dickbankiger
Kalke überlagert. Sie beginnt mit einem 60 cm mächtigen
Fossilschuttkalk, der hauptsächlich aus Echinoder-
menschutt besteht. 2,5 m hangend enthält ein 1 m mäch-
tiger, knolliger Kalk Weyla und häufig desmodonte Mu-
scheln. Selten kommen ‚‚Rhynchonella“, Lopha longi-
striata, Modiolus, Plagiostoma und Lithotrochus andinus
vor. Über diesem Knollenkalk liegt ein 1 m mächtiger
Fossilschuttkalk mit viel Echinodermenschutt (u. a. See-
igelstachel). Es folgen weiterhin dickbankige Fossil-
schuttkalke (bis 1,5 m ®) mit geringmächtigen Mergel-
zwischenlagen. Im hangenden Abschnitt ist dieser Kalk-
bankserie ein 20 m mächtiger, intrusiver Porphyrit einge-
schaltet. Über ihm werden die Kalke allmählich dünnban-
kiger und gehen in eine Wechsellagerung von 20 bis 40 cm
gebankten Fossilschuttkalken mit bis 1 m mächtigen Mer-
gelzwischenlagen über. Etwa 10 m im Hangenden des
Porphyrit ist Spiriferina sehr häufig, wenig oberhalb die-
ses Horizontes kommt Montlivaltia und in beiden
Schichten ‚„‚Rhynchonella“ und ‚Terebratula“ häufig
vor. In diesem Schichtbereich wurde in der Quebrada
Chanchoquin ein Eoderoceras ex gr. E. armatum gefun-
den, was für eine Einstufung dieser Schichten in das hö-
here Ober-Sinemurium spricht.

Im obersten Abschnitt dieser Kalk-Mergel-Serie wer-
den die Mergellagen wieder geringermächtig, bis 1m
mächtige Fossilschuttkalkbänke kommen vor.

Es folgt eine Steilstufe aus dickbankigen, z. T. feinsan-
digen und fossilschuttreichen Kalken. In einzelnen Bän-
ken sind ‚„‚Rhynchonella“ und ‚‚Terebratula“ häufig. Im
mittleren Teil tritt eine Schichtmit Gryphaea auf. Im obe-
ren Teil ist Weyla nicht selten, und in den hangendsten
Bänken sind sehr häufig Bryozoen vorhanden.

Die von Zrır (1960, $. 653) aus der Quebrada Pinte an-
gegebene Uptonia cf. jamesoni (Sow.) stammt aus der
Kalk-Mergel-Serie oder den basalen Fossilschuttkalken
der folgenden Serie.

Oberhalb der Quebrada Chanchoquin bilden die dick-
bankigen Kalke ebenfalls eine kleine Steilstufe. An der Ba-
sis wurde das Bruchstück eines zu den Polymorphitinae
zu stellenden Ammoniten gefunden (s. a. v. HILLEBRANDT
1973b, S. 197), im mittleren Teil ein mäßig erhaltenes
Radstockiceras cf. behrendseni (Jaw.). Beide Ammoniten
sprechen für eine Einstufung dieser Schichten in das un-
tere Pliensbachium (+ ibex-Zone).

Über dieser Steilstufe liegen Mürbsandsteine, die mit
Mergeln wechsellagern und Radtstockiceras sp. 1 enthal-
ten. Es folgen vorwiegend gelbliche Mergel, schiefrige
Kalke und dünnbankige Kalke. In diesen Schichten wurde
2,2 km SW Punkt 2360 Radstockiceras sp., Protogram-
moceras cf. normanianum (D’ORrs.) und Atractites ge-
funden (+ davoei-Zone).

Die dünnbankigen Kalke gehen über in eine Wechsella-
gerung von rötlichen, feinsandigen, gut gebankten (10 bis
40 m ®) Kalken mit 10 bis 50 cm mächtigen, rötlichen

Mergeln. Diese Schichtfolge wird von einem 2 bis 3 m
mächtigen, rötlichen, in sich gebankten, knolligen Sand-
stein mit Fossilschutt überlagert, in dem Weyla, Mesomil-
tha, Pleuromya und Cenoceras vorkommen. Im han-
gendsten Teil ist der Sandstein mürb, enthält zahlreiche
Bohrgänge, reichlich Fossilschutt und 2,2 km SW Punkt
2360 wurde ein Radstockiceras sp. 2 mit 25 cm Durch-
messer gefunden.

Anschließend folgen wieder graue, feinsandige, gut ge-
bankte (10 bis40 cm) Kalke, die mit Mergeln (20 bis50 cm
®) wechsellagern. Bis etwa 10 m über der rötlichen Sand-
steinbank wurde Radstockiceras gefunden. In der Que-
brada Chanchoquin fehlt diese rötliche Sandsteinbank,
und in diesem Schichtbereich tritt zusätzlich zu Radstok-
kiceras Argutarpites und Lytoceras auf (+ spinatus-
Zone).

Im Hangendteil sind die Schichten wieder rötlich ge-
färbt und sie werden von roten, feinkörnigen Sandsteinen
(20 bis 40 cm gebankt) überlagert, die z. T. Echinoder-
menschutt enthalten. Nach ca. 3 m Mächtigkeit ist den
Sandsteinen ein 40 cm mächtiger Fossilschuttkalk mit
„Terebratula“ und Weyla eingeschaltet. Diese Kalkbank
geht nach SW in eine zunächst 1 m mächtige, dann 3 m
mächtige (350 mSW Punkt 2360), in sich gebankte Luma-
chelle bis Fossilschuttkalk über, der auch hier von etwa
3 m mächtigen, roten Sandsteinen unterlagert wird. Über
dieser Lumachelle/Fossilschuttkalk liegt eine aus 2 Bän-
ken bestehende, insgesamt 2 m mächtige Lumachelle, die
sich aus den Bruchstücken von Plicatostylus zusammen-
setzt.

Im Bereich des Normalprofils (ca. 250 m östl.
Punkt 2360) folgen über der 40 cm Kalkbank nochmals
ca. 20 m mächtige, fein- bis mittelkörnige, rote Sandstei-
ne. Etwa 4 m unterhalb der Hangendgrenze ist eine etwa
1 m mächtige Zone mit häufig Pholadomya cf. fidicula
Sow. und Pleuromya, selten Myophorella, Cercomya und
Gastropodensteinkernen, schlecht
Bruchstücken eines großwüchsigen Peronoceras einge-
schaltet.

Den Abschluß der Sandsteine bildet ein 50 cm mächti-
ger, grauer Fossilschuttkalk, der im Hangendteil reich an
Fossilien ist:

„Rhynchonella“ sp. h

‚„‚Terebratula“ sp. h

Liostrea sp. h

Lopha sp. s

Modiolus cf. baylei (PhiLiprr) h
Pseudolimea sp. ss

Plagiostoma sp. ss

Trigonia sp. s

Myophorella sp. s

Pholadomya cf. fidicula Sow. h
Pleuromya sp. h

Zygopleura sp. s

Catacoeloceras (?) sp. s

Collına chılensis n. sp. h

Harpoceras cf. subexaratum (BON.) s
Phymatoceras ex gr. P. erbaense (HAUER) h
Hildoceratidae gen. et sp. indet (3 Arten) h

sowie erhaltenen

Über dieser Fossilbank liegen ca. 10 m mächtige Mergel
mit knolligen Fossilschuttkalkbänken. Die Schichten sind
fossilreich und es kommen vor:

„Rhynchonella“ sp. h
‚‚Terebratula“ sp. h

Liostrea sp. s

Grammatodon sp. s

Modiolus cf. scalprum Sow. h
Entolium sp. s

Pseudolimea sp. s

Myophorella sp. h

Mesomiltha sp. s

Pleuromya sp. sh

Phymatoceras cf. fabale (SıMPsON) h
Phymatoceras ex gr. P. lilli (HAUER) h

In den hangenden Mergeln werden Kalkbänke wieder
häufiger. Im oberen Teil kommen Fossilschuttkalke vor.
Die Fauna setzt sich zusammen aus:

„Rhynchonella“ sp. s

„Terebratula“ sp. sh

Lopha sp. s

Modiolus sp. s

Eopecten cf. tuberculosus (GOLDF.) s
Ctenostreon sp. S

Plagiostoma cf. gigantea (SOW.) s
Psendolimea sp. s

Trigonia sp. s

Phymatoceras copiapense (MÖRICKE) h
Phlyseogrammoceras cf. tennicostatum (JAW.) s
Pleydellia (Walkericeras) sp. s

Die Fauna umfaßt mehrere Zonen (Subzonen) des obe-
ren Toarcium.

Die Mergelserie wird von einem ca. 3 m mächtigen,
sandigen Fossilschuttkalk überlagert, in dessen hangen-
dem Teil folgende Fossilien vorkommen:

„Rhynchonella“ sp. s
Costigervillia sp. ss
Trigonia sp. h
Pleuromya sp. s
Seeigelstachel

Zwischen der Quebrada Chanchoquin und der Que-
brada Acevedo ist dieser sandige Fossilschuttkalk sehr fos-
silreich und enthält:

Actinastrea sp. h

„Rhynchonella“ sp. s

„‚Terebratula“ sp. h

Lopha sp. s

Grammatodon sp. (großwüchsig) h
Entolium cf. demissum (PHILIPPS) s
Eopecten cf. tuberculosus (GOLDF.) s
Trigonia sp. h

Myophorella sp. s

Vaugonia sp. s

Mesomiltha cf. bellona (D’ORB.) h
Mesomiltha sp. (großwüchsig) s
Neocrassina cf. andium (GOTTSCHE) s
Protocardia sp. s

Pholadomya cf. plagemanni MÖRICKE h
Pleuromya sp. h

Cercomya iglesiae MÖRICKE h
Bredyia sp. s

sen Sandsteinen kommt im Profil der Quebrada Cancho-
quin eine großwüchsige Ceratomya (?) und Bredyia vor
(unteres Aalenium).

Hangend folgt ein ca. 2 m mächtiger Grobsandstein mit
Fossilschutt und Geröllen (bis 5 cm ®). Dieser Horizont
ist südlich der Quebrada Acevedo (r. Seitenquebrada der
Qu. Chanchoquin) als Konglomerat ausgebildet, das
z. T. taschenförmig und in Spalten bis 25 cm tief in den
liegenden Sandstein greift. Im Hangendteil des Konglo-
merats ist Trigonia häufig und es wurde eine Fontannesia
(?) anstroamericana Jaw. gefunden (oberes Aalenium).

Den Abschluß des Juraprofils bilden graue, dichte, gut
gebankte Kalke mit häufig Mesomiltha intumescens
(GOTTSCHE) und Bruchstücken von Sonninia (Papilliceras)
espinazitensis TORNQuısT (unt. Bajocium, sauzei-Zone).

In der Quebrada Acevedo kommen im sandigen, lie-
genden Teil der Kalke Psendotoites sphaeroceroides
(Tornausst) und Sonninia (Papilliceras) altecostata
(TornQusst) vor (unt. Bajocium, „‚sowerbyi“/ sauzei-
Zone).

Über dem Jura liegen Porphyrite.

! Phymatoceras copıapense 9
thouarsense

>. (Ferne m =]

2 variabilis Phymatoceras cf fabale, Phym.cf Iıllı — = som

o Be u. -2 ar

Ss bifrons Plicatostylus 7

m IoR Saat; Mercatıceras sp -6

hoelderı Harpoceratoides sp, Bouleiceras chilense — —5

_tenuicostatum| Dact (Eodact)simplex., Bouleiceras cf chakdallaense =

EEE

= Cardinta, Myoconcha, Ctenostreon 3

m) “Rhynchonella','Terebratula" 2

mE *Lucina' sp., Myophorella sp. =]

Abb. 11:

Teilprofil des Jura bei der Vereinigung der Quebrada Chanchoquin mit der Quebrada La Totora

(‚„‚Steinbruch-Profil‘“‘); Legende zur Gesteinsausbildung Abb. 10.

2.18.2 Profil Quebrada Chanchoquin/Paitepen
(Abb. 1, Profil 21; Abb. 11)

Das Profil an der Vereinigung der Quebrada Chancho-
quin mit der Quebrada Paitepen wurde bei v. Hırte-
BRANDT (1973a, S. 353, 354) beschrieben. Im Liegenden
der Plicatostylus-Kalke (Abb. 11) ist eine Serie gut ge-
bankter Kalke aufgeschlossen, die im Abstand von 2 bis
3m 2 Ammoniten-Horizonte enthält. Im tieferen Hori-
zont kommen sehr häufig Dactylioceratidae vor. Die ur-
sprüngliche Bestimmung bei v. Hıresranpr (1973a) muß
korrigiert werden. Der tiefere Horizont enthält nunmehr
folgende Arten:

Dactylioceras (Eodactylites) simplex Fucını h
Dactylioceras (Orthodactylites) direttum (BUCKMAN) h
Dactylioceras (Orthodactylites) anguinum (REINECKE) s
Nodicoeloceras cf..eikenbergi (HOFFMANN) ss
Nodicoeloceras cf. psenudosemicelatum (MAUBEUGE) h
Radstockiceras sp. ss

Bouleiceras cf. chakdallaense FATMI ss

Die Fauna des höheren Horizontes setzt sich zusammen
aus:
Vaugonia n. sp. (cf. V. oregonensis POULTON) h
Mesomiltha huayguimili (LEANZA) h
Discohelix sp. h
Cenoceras sp. SS
Harpoceratoides sp. ss
Hiıldaites sp. ss
Bonleiceras chilense v. HILLEBRANDT h
Bouleiceras cf. chilense v. HILLEBRANDT h

3. PALÄAONTOLOGISCHER TEIL

3.1 GENUS: DACTYLIOCERAS HYATT, 1867

Typus-Art: Ammonites communis SOWERBY, 1815

Diagnose: (ausführliche Charakteristik siehe
SCHMIDT-ErrinG 1972: 54-55): Evolute, flach-scheibige,
serpentikone Gehäuse, die selten 10 cm Durchmesser
überschreiten. Ontogenetische
sind in der Regel wenig ausgeprägt. Der Windungsquer-
schnitt ist hochoval bis rundlich. Die Skulptur wird aus

Merkmalsänderungen

geraden, nur selten leicht geschwungenen Flankenrippen,
die sich am Außenbug in 2 bis 3 Externrippen teilen und
ununterbrochen die Externseite queren, gebildet. Außer-
dem können Schaltrippen und ungeteilt durchlaufende
Einfachrippen auftreten, seltener, und dann immer an be-
stimmte Windungsabschnitte gebunden, werden Dornen
bzw. Knoten an den Rippenspaltpunkten, auch fibulate
Rippen beobachtet.

Bemerkungen: Inder Terminologie und Morpholo-
gie des Dactylioceraten-Gehäuses folge ich SCHMIDT-Er-
FING (1972: 21-30), in der Taxonomie entsprechend (1972:
54-62). Von Guzx (1973b) abgesehen sind zu diesen Ge-
bieten inzwischen keine neuen Beiträge erfolgt
(SCHMIDT-ErrinG 1975). HOwARTH (1973: 247) weist auf
die große Variabilität der Dactylioceras- Arten hin. RocHA
(1976: 96-97) gibt einen historischen Überblick, Kryu-
coLz (1974b) eine Artenliste.

Verbreitung: Höchstes Domerium bis Mittel-Toar-
cıum (bifrons-Zone); weltweit.

3.1.1 Subgenus:
Dactylioceras (Eodactylites) SCHMIDT-ErFing, 1972

Typus-Art: Dactylioceras psendocommune Fucıtı,
1935

Diagnose: Ein Subgenus von Dactylioceras, das sich
durch kräftige Rippen, wobei die Externrippen häufig ge-
spreizt sind und zu den Flankenrippen abgewinkelt ste-
hen, und häufig auch durch eine im Querschnitt keilför-
mig zugespitzte Externfläche auszeichnet. Der Win-
dungsquerschnitt ist im Alter immer hoch oval, im Be-
reich der jüngeren Windungen jedoch rundlich bis breit
oval.

Bemerkungen: Gerade durch die ausgeprägteren on-
togenetischen Merkmalsänderungen springt das Subgenus
etwas aus dem Rahmen der allgemeinen Gattungsdiagno-
se. Seine Arten sind von dem stratigraphisch folgenden
Dactylioceras (Orthodactylites) sehr verschieden, von
dem erst viel höher folgenden D. (Dactylioceras) weniger
verschieden (HowArTH 1978: 252). Doch sind auch diese

beiden Subgenera in allen Eigenschaften, nicht nur mor-
phologisch, so verschieden, daß ihre Unterscheidung ge-
rechtfertigt ist. So sind sie stratigraphisch durch große
Teile des gesamten Unter-Toarciums getrennt. Bioge-
ographisch ist Eodactylites auf die mediterrane Faunen-
provinz beschränkt, wobei sein Auftreten in Chile als
starker mediterraner Einfluß zu werten ist. Dactylioceras
ist zwar weltweit verbreitet, doch im Mediterran allge-
mein selten. Für die mediterrane Stratigraphie und Pa-
läontologie hat sich die Aufstellung des Subgenus als prak-
tisch erwiesen (z. B. Eımı, Arrops & Mancoıp 1974: 54).

Verbreitung: Höchstes Domerium und tieferes Un-
ter-Toarcium des Mediterrans (mirabile-Subzone) und

Chiles (simplex-Subzone).

3.1.1.1 Dactylioceras (Eodactylites) simplex
Fuciını, 1935
Taf. 1, Fig. 144; Abb. 12, 16a, b

1935 Dactylioceras simplex n. sp. - Fucını: 86-87, Taf. 9,

Fig. 455.
?1935 Dactylioceras polymorphum n. sp. — FUCINI: 88 (pars),

Taf. 9, Fig. 13.

1935 Coeloceras ? cfr. Sellae (GEMM.)- Fucını: 92, Taf. 8, Fig.
11-12.

1966 Dactylioceras simplex FUCmI — FISCHER: 23, Taf. 1,
Fig. 2, Taf. 3, Fig. 5-6, Taf. 4, Fig. 7.

1968 Dactylioceras polymorphum FUC. — CANTALUPPI & SAVI:
231, (pars), Taf. 20, Fig. 2, 3.

1971 Dactylioceras (Dactylioceras) simplex Fucını, 1935. —
PınnA & LEVI-SETTI: Taf. 1, Fig. 9.

1972 Dactylioceras simplex FUCINI, 1935 — FERRETTI: 108,

Taf. 18, Fig. 1.
1973a ,„‚Catacoeloceras“ simplex (Fuc.) — GUEx: 509, Taf. 12,
Fig. 11.
Material: Quebrada Chanchoquin (Abb. 1, Pro-
fil21; Abb. 10, Schicht 4), topographische Kar-
te 1:50000, Blatt EI Tränsito: x = 375,1 km,

y = 6811,05 km. Profilbeschreibung siehe v. Hırre-
BRANDT (1973a: 353-354). Die Dactylioceraten stammen
aus dem tieferen Horizont, zusammen mit sehr seltenen
Radstockiceras sp. und Bonleiceras cf. chakdallaense
Farmi. Sieben Exemplare (B. St. M. 1978 II 1-7) und
zwei weitere Bruchstücke (B. St. M. 1978 II 8-9).

Erhaltung: Steinkernerhaltung, wobei die Schalen
verkieselt sind. Besonders günstig sind erhalten: Nr. 7
(Teile von5 Umgängen des Phragmokons), Nr. 4(4 Um-
gänge des Phragmokons und ein Stück der Wohnkammer)
und Nr. 5 (3'/, Umgänge des Phragmokons). Bei den
restlichen Exemplaren sind 2 bis5 Umgänge jeweils erhal-
ten, wobei diese teilweise verdrückt sind.

Maße (in mm):

Nr. DM WH WB NW WB/WH
4 ursprünglicher Gesamtdurchmesser mindestens 70 mm

£ 46,0 12,5 (0,27) 14,0 (0,30) 22,5 (0,49) (1,12)
4 45,5 14,0 (0,31) 18,0 (0,40) 22,2 (0,49) (1,29)
1 35,0 = = 18,0 (0,51) =
5 ca. 35 10,0 (0,29) 13,5 (0,39) ca. 17 (0,49) (1,35)
3 34,5 10,0 (0,29) ca. 12 (0,35) 16,5 (0,48) (25)
2 34,5 10,0 (0,29) —_ 16,0 (0,46) —
7 — Ba I zZ (1,22)
7 a EN en = (1,26)
7 — oa GD = (1,50)

Beschreibung: Die Gehäuse sind weit genabelt und
gedrungen, der Nabel ist napfförmig eingesenkt. Der
Windungsquerschnitt der frühen Umgänge ist sehr breit
oval, der letzten Umgänge, besonders des letzten, breit-
rundlich, wobei die Flanken auf dem letzten Umgang
(Wohnkammer) stärker abgeflacht sind. Die Flanken
knicken scharf an der Nabelkante in eine senkrechte, hohe
Nabelfläche um. Die Externfläche ist sehr breit gerundet;
die Flanken sind schmal. Die konkave Windungszone der
inneren Umgänge beträgt etwa '/,, des äußeren Umganges
jedoch nur '/s.

Die Rippen setzen auf der Nabelfläche ein, erreichen
ihre volle Stärke an der Nabelkante, verlaufen rectoradiat,
auf den innersten Umgängen teils proradiat, über die
Flanke und gabeln sich am Außenbug in 2 bis 3 gleichwer-
tige Externrippen auf. Die Flankenrippen sind breit und
kräftig. Die Rippenspaltpunkte liegen auf einer geraden
Linie, wobei sie auf den inneren Umgängen Dornen tra-
gen. Die Interkostalräume sind relativ breit. Die Extern-
rippen sind fein (Ausnahme Exemplar 7 mit scharfen Ex-
ternrippen) und stehen dicht. Nr. 14 besitzt bei einem
Durchmesser von 46 mm auf dem letzten Umgang
(Phragmokon) 37 Flanken- und ca. 90 Externrippen, auf
dem vorletzten Umgang 24 und auf dem drittletzten Um-
gang ca. 19 Flankenrippen. Die Externrippen verlaufen
leicht asymmetrisch, da sie leicht proximal ausgebaucht
sind, über die Externfläche.

Abb. 12: Dactylioceras (Eodactylites)simplex Fucını, 1935;
Quebrada Chanchoquin; B. St. M. 1978 II 4; nat. Gr.

Das Exemplar 4 ist wohl das Fragment eines adulten
Gehäuses. Denn die hier teilweise erhaltene Wohnkam-
mer zeigt deutliche Wachstumsunterschiede gegenüber
den inneren Umgängen: sie ist im Verhältnis höher, be-
sitzt eine schmalere konkave Windungszone und zeigt
eine andersartige Skulptur, nämlich die Rippen stehen we-
sentlich dichter, sind schärfer und verlaufen auf der Na-
belfläche proklin (Externrippen sind nicht günstig beob-
achtbar).

Die Exemplare Nr. 5 und Nr. 7 lassen an freien Septal-
flächen auch die Lobenlinie erkennen. Diese stimmt im
wesentlichen mit der Abb. 15 (ScHiNDEwoLF 1962: 589)
für Dactylioceras commune überein: Soweit erkennbar,
sind drei U vorhanden. U, scheint gespalten zu sein. Der
Externsattel ist hier breiter als bei Dactylioceras commu-
ne.

Vergleich: Alle neun Exemplare bzw. Bruchstücke
stimmen in den beschriebenen Merkmalen gut miteinan-
der überein. Lediglich Exemplar Nr. 2 besitzt auf den
beiden erhaltenen Windungsfragmenten (Durchmesser
maximal 35 mm) ausgeprägt proradiate Rippen. Es
herrscht gute Übereinstimmung mit den Angaben in der
Literatur (vgl. Synonymieliste). Besonders wertvoll für
einen Vergleich ist die Beschreibung von FiscHEr (1966:
23). Eine deutliche Variabilität ist nur in der Dichte der
Flankenrippen erkennbar.

Bemerkungen: Dactylioceras (Eodactylites) simplex
zeigt in beispielhafter Weise einen palingenetischen
Merkmalswechsel von einem charakteristischen Dactylio-
ceraten (Coeloderoceras) des Pliensbachium im Bereich
der Innenwindungen zu einem Dactylioceras, wie er für
das Toarcium so typisch ist, im Bereich der äußeren Win-
dungen und besonders der Wohnkammer. Die gehäuse-
morphologische Trennung von Coeloderoceras und Dac-
tylioceras ist in einem solchen Übergangsbereich schwie-
rigund nur durch Übereinkunft zu lösen (SCHMIDT-EFFING
1975: 94). Das Auftreten neuer Merkmale rechtfertigt je-
doch die Zuordnung dieser Formen zu Dactylioceras, was
für die biostratigraphische Definition der Pliensba-
chium/Toarcium-Grenze auch einen hohen praktischen
stratigraphischen Wert besitzt (Eımi et al. 1974: 54). Da-
her möchte ich diese Formen von Coeloderoceras, wel-

chem ich sie 1972 (SCHMIDT-EFFING: 88) zunächst zuge-
ordnet hatte, trennen.

Die Merkmale wechseln zu verschiedenen Zeitpunkten
der Ontogenese: als erstes setzt die Bedornung der Rip-
penspaltpunkte aus, dann erniedrigt sich die Zahl der Ex-
ternrippen von 3 auf 2 pro Flankenrippe, später verändert
sich der Windungsquerschnitt von breit oval in hoch oval,
und mit diesem Merkmal kombiniert werden die Flanken-
rippen wesentlich länger und stehen dichter.

Von einem ähnlichen Fall bei Coeloderoceras cf. ponti-
cum habe ich 1972 (ScHmiDT-Erring: 90) berichtet. Unter
Berücksichtigung der hier angeführten Gesichtspunkte
stelle ich heute diese Form zu Dactylioceras (Eodactylıtes)
cf. polymorphum.

Verbreitung: Dactylioceras (Eodactylites) simplex,
wie auch die anderen Arten dieser Untergattung, sind auf
die mediterrane Faunenprovinz beschränkt. Nur sehr ver-
einzelt werden sie auch in der nordwesteuropäischen Pro-
vinz gefunden (ScHmiDr-Errins 1972: 143; HOWARTH
1973: 253). Die Häufigkeit dieser, neben anderen Arten,
in Chile weist damit eindeutig auf mediterranen Einfluß
hin, also eine zoogeographische Beziehung, die im älteren
Unterjura Chiles weniger deutlich zu beobachten ist
(SCHMIDT-EFFinG 1976: 215).

Stratigraphisch tritt Eodactylites immer im Liegenden
der Schichten auf, die reichlich D. (Orthodactylites) und
besonders die Leitarten D. tenuicostatum und D. semice-
latum führen. Daher haben Eıni et al. (1974: 55) im Rah-
men ihrer mediterranen Zonengliederung im Liegenden
der semicelatum-Subz.one die Subzone des D. (Eodactyl-
tes) mirabile ausgeschieden. Zeit-stratigraphisch ent-
spricht diese Subzone im wesentlichen dem tieferen Ab-
schnitt der nordwesteuropäischen tenuicostatum-Zone —
hier gebraucht als abstrahierende Zone im Sinn von Ho-
WARTH (1978), denn D. tenuicostatum tritt in diesen
Schichten überhaupt nicht auf -; sie reicht jedoch eindeu-
tig auch noch in die höchsten Schichten mit Pleuroceras
(SCHMIDT-EFFING 1972: viele Beispiele; HowartH 1973:
255;.1978:,252).

3.1.2 Subgenus: Dactylioceras (Orthodactylites)
Buckman, 1926
Typus-Art: Orthodactylites directus Buckman,
1926.

Diagnose: Ein Subgenus von Dactylioceras mitrund-
lichem bis hoch ovalem Windungsquerschnitt, der sich
während der Ontogenese wenig verändert, mit relativ un-
differenzierten Rippen, wobei die annularen Flanken- und
Externrippen ähnlich entwickelt sind und rectoradiat bis
proradiat verlaufen. Gabelrippen wechseln häufig mit

Einfach- und Schaltrippen ab. Die Skulptur ist weniger
kräftig und unregelmäßiger als bei beiden anderen Subge-
nera ausgebildet. Bei verschiedenen Arten treten manch-
mal, besonders auf den Innenwindungen, Dornen bzw.
Knoten an den Rippenspaltpunkten auf; auch fibulate
Rippen werden vereinzelt beobachtet.

Verbreitung: Orthodactylites ist ein ausgesproche-
ner Kosmopolit mit Verbreitung- und Artenmaxima in
der nordwesteuropäischen und der borealen Provinz
(SCHMIDT-EFFinG 1972: 57). Stratigraphisch ist er an die
tenuicostatum- und die falcıfer-Zone gebunden und tritt
damit später als der dickrippige Eodactylites auf.

3.1.2.1 Dactylioceras (Orthodactylites) anguinum
(REINECKE, 1818)
Taf. 1, Fig. 57; Abb. 16c, d

1818 Argonanta angninus — REINECKE: 83, Taf. 12, Fig. 73.

1885 Ammonites angninus - QUENSTEDT: Taf. 46, Fig. 9 (von
SCHMIDT-EFFING 1972: 183 als Neotyp für den verlore-
nen Holotyp vorgeschlagen).

?1898 Coeloceras (Dactylioceras) anguinum REINECKE sp. —

EluG: 23, Taf. 6, Fig. 2.

1927 Coeloceras (Dactylioceras) anguinum REINECKE —
SCHRODER: 101, Taf. 4 (11), Fig. 2.

1928 Anguidactylites anguiformis S. BUCKMAN — BUCKMAN:
Taf. 763.

1965 Dactylioceras angninum (REINECKE) — PANNKOKE: 22,
Taf. 2, Fig:

1966 Dactylioceras anguinum (REINECKE) — FISCHER: 22,
Taf./3, Fig. 9:

1972 Dactylioceras (Orthodactylites) anguinum (REINECKE) —

SCHMIDT-EFFING: 57 u. 183, Taf. 7, Fig. 5a, b.
?1973a Nodicoeloceras cf. spicatum (BUCK.) — GUEX: 509,
Taf..13,/ Pig. 3.
Dactylioceras anguinum (REINECKE, sensu QUENSTEDT
1885) - SCHLEGELMILCH: 77, Taf. 38, Fig. 8 (Abbildung
des Neotyps.).

Material: a) Quebrada El Asiento (Abb. 2, Profil 3;
Abb. 3, Schicht 4), topographische Karte 1:100000,
Blatt Potrerillos: x = 467,5 km, y = 7070,45 km. Zwei
Exemplare (B. St. M. 1978 II 10-11) als Steinkerne teil-
weise mit Schale, zusammen mit Hildaites cf. serpentini-
formis (Buckman) und Harpoceratoides cf. alternatus
(SIMPSON).

b) Quebrada Chanchoquin (Abb. 1, Profil 21;
Abb. 10, Schicht 4), topographische Karte 1:50000, Blatt
El Tränsito: x = 375,1 km, y = 6811,05 km. Profilbe-
schreibung siehe v. HırLesranpt (1973a: 353-354). Die
Dactylioceraten stammen aus dem tieferen Horizont, zu-
sammen mit sehr seltenen Radstockiceras sp. und Boulei-
ceras cf.chakdallaense Farmı. Zwei Exemplare (B. St. M.
1978 II 12: Teil des Phragmokons; B. St. M. 1978 II 13:
Phragmokon und halber Umgang der Wohnkammer),
Steinkerne mit verkieselter Schale.

1976

Maße (in mm):

Expl. DM WH WB NW WB/WH

Neotyp 41,4 12,0 (0,29) 11,0. (0,27) 20,5 (0,50) (0,92)
13 41,0 ca.12,0 (0,29) 13,5 (0,33) 18,5 (0,45) (1,12)
11 33,2 11,0 (0,31) 12,0 (0,34) 19,5” (0,55) (1,09)
12 22,0 7,2 (0,33) 9,8 (0,45) 9,2 (0,42) (1,36)

Beschreibung: Evolute Gehäuse, die breit ovale In-
nenwindungen und rundliche äußere Umgänge besitzen.
Weder Nabel- noch Externkante sind ausgebildet.

Die Rippen stehen sehr dicht, besitzen eine relativ breite
Rippenbasis, wie sie bei Steinkernerhaltung sichtbar wird,
bilden jedoch scharfe Rippengrate, wie es bei Schalener-
haltung zu beobachten ist. Exemplar Nr. 10 hat auf dem
letzten Umgang etwa 60, Exemplar Nr. 12 etwa 45 Flan-
kenrippen. Flanken- und Externrippen verlaufen rectora-
diat und sind sehr gleichmäßig ausgebildet (annulat). Die
Rippenspaltpunkte sind völlig unverdickt und liegen et-
was unregelmäßig am Außenbug der Flanken. Die Flan-
kenrippen spalten in sehr spitzem Winkel in zwei gleichar-
uge Externrippen. Auch Schaltrippen treten auf, beson-
ders häufig in der letzten Windung. Rippen und Interko-
stalräume sind etwa von gleicher Breite.

Vergleich: Untereinander stimmen die vorliegenden
vier Exemplare gut überein. Sie unterscheiden sich jedoch
in zwei Merkmalen vom Neotyp: Dieser besitzt nämlich
einen nicht so ausgeprägten breit ovalen Windungsquer-
schnitt (diagenetische Ursache ?), außerdem zeigt er auf
den innersten Windungen, bis etwa 2 cm Durchmesser,
noch feinere Rippen, die z. T. fibulat sind. Während der
Windungsquerschnitt generell variabler sein mag, ist die-
ser auffallende Unterschied in der Berippung ın seiner Be-
deutung nicht einwandfrei bewertbar. Ihm scheint jedoch
kaum eine arttrennende, allenfalls subspezifische Bedeu-
tung zuzukommen, wie das auch für die Skulpturvariatio-
nen von Dactylioceras (Orthodactylites) directum gilt
(SCHMIDT-Erring 1975: 80).

Bemerkungen: In der Literatur und zwar besonders
in den Fossillisten der älteren Arbeiten, werden sehr ver-
schiedene Formen als Dactylioceras angninum aufge-
führt. Dies dürfte auf der mehrdeutigen Abbildung und
der ungenügenden Beschreibung des Holotyps beruhen,
der außerdem verloren ist (Zeiss 1972: 38). In der letzten
Zeit gaben PAnnKoke (1965) und besonders FiscHe£r (1966)
sehr treffende Beschreibungen. ScHmiDT-Erring (1972:
183) bestimmte das Exemplar von Quenxstepr (1885:
Taf. 46, Fig. 9) als Neotyp. Wegen der darstellerischen
Mängel und der Seltenheit des Werkes von REınzck£, sind
die meisten früheren Bestimmungen ohnehin nach diesem
Stück vorgenommen worden. Wie schon FiscHEr fest-
stellt, gehört Dactylioceras anguinum in die nähere Ver-
wandtschaft von Dactylioceras (Orthodactylites) tenuicos-
tatum. Es unterscheidet sich von diesem jedoch deutlich
durch dichter stehende und feinere Rippen und durch
breitere Umgänge.

Dactylioceras (Orthodactylites) anguinum wurde bis-
her aus der mediterranen Provinz zwar nur gelegentlich
gemeldet, doch wie ein Vergleich mit zahlreichen Formen
in Pınna & Levi-Serti (1972) zeigt, tritt diese Art bzw. au-
ßerordentlich nah verwandte Formen hier sogar häufiger
auf als in NW-Europa. Die verschiedenen Erhaltungen —
hier kalkige, reine Steinkernerhaltung, dort diagenetisch
mehr oder weniger komprimierte Kalkmergel-Steinkerne,
häufig mit Schale - verursachen scheinbare Unterschiede.
Das Dactylioceras (Örthodactylites) angninum, das auf
Taf. 3., Fig. 1 (Pınna & Levi-Serti 1972) abgebildet ist,
gehört allerdings einer anderen Art an. Doch stehen viele
Formen, die zu Mesodactylites merlai (z. B. Taf. 3,
Fig. 8a, b, 11), zu M. mediterraneus, M. ghinii, M. sap-
phicus und zu Nodicoeloceras gestellt werden, dem ech-
ten Dactylioceras (OÖrthodactylites) anguinum sehr nahe.

Verbreitung: Unter-Toarcium der nordwest-

europäischen und der mediterranen Provinz und Chile.

3.1.2.2 Dactylioceras (Orthodactylites) directum
(Buckman, 1926)
Taf. 1, Fig. 8-11; Abb. 13, 16f

1926 Orthodactylites directum, nov. — BUCKMAN: pl. 564.

1927 Orthodactylites mitis, nov. — BUCKMAN: pl. 738.

1957 Dactylioceras directus S. BUCKMAN — MAUBEUGE: 216,
Taf. 26, Fig. 52-56.

?1971 Rakusites pruddeni n. sp.- GUEX: 238, Taf. 1, Fig. 1a-c,
Taf. 3, Fig. 5 (vgl. SCHMIDT-EFFING 1975: 80).

1972 Dactylioceras (Orthodactylites) directum (BUCKMAN,
1926) — SCHMIDT-EFFING: 107-109, Taf. 7, Fig. 4a, b,

Taf. 18, Fig. 14.
Material: a) Quebrada Chanchoquin (Abb. 1, Pro-
fil 21; Abb. 10, Schicht 4), topographische Karte
1:50000, Blatt EI Tränsito: x =375,1km, y=

6811,05 km. Profilbeschreibung siehe v. HıLLEBRANDT
(1973 a: 353-354). Die Dactylioceraten stammen aus dem
tieferen Horizont, zusammen mit sehr seltenen Radstok-
kiceras sp. und Bouleiceras cf. chakdallaense Farmı. Die
Schalen sind verkieselt, die Hohlräume als Steinkerne er-
halten, wobei die Wohnkammer von einem feinsandigen
Kalk, der Phragmokon vorzugsweise von Kalzit ausge-
füllt ist. Das besonders günstig erhaltene Exemplar Nr. 14
besitzt 2'/, Umgänge des Phragmokons, ein weiterer äu-
ßerer Umgang ist durch ein Nabelband angedeutet, die in-
nersten Windungen, bis etwa 7 mm, sind nicht erhalten.

b) Quebrada Noria, 700 m SSW Punkt 3132 (südlich
Salto de la Muerte), (Abb. 1, Profil 12; Abb. 8,
Schicht 4), topographische Karte 1:100000, Blatt Carrera
Pinto: x=426,5 km, y = 6970,6 km. Vier Exemplare

(B. St. M. 1978 II 20-23), Steinkerne teilweise mit Schale.
Zusammen mit Dactylioceras (Orthodactylites) hoelderi
n. sp., Dactylioceras (?Orthodactylites) helianthoides und
Elegenticeras cf. elegantulum (Young & Biro).

c) Quebrada Yerbas Buenas (Abb. 1, Profil 9; Abb. 6,
Schicht 6), topographische Karte 1:100000, Blatt Carrera
Pinto: x = 439,4 km, y = 6979,3 km. Ein Exemplar (B.
St.M. 1978 II 24) und drei weitere Bruchstücke, die wahr-
scheinlich zu D. (O.) directum zu stellen sind (B. St. M.

1978 11 25-27), Steinkerne; zusammen mit Dactylioceras
(Orthodactylites) hoelderi n. sp.

d) Rio Jorquera (Majada del Carrizo), (Abb. 1, Pro-
fil 14), topographische Karte 1:100000, Blatt La Guardia:
x = 437,4 km, y = 6931,7 km. 4 Exemplare (B. St. M.
1978 1128, 229-231), Steinkern, zusammen mit Nodicoe-
loceras cf. Crassoides FORM C, Hildaites cf. levisoni
(großwüchsig) und Harpoceras cf. falcıfer.

Maße (in mm):
Nr. DM WH WB NW WB/WH
17 51,0 — — —
14 45,0 12,3 (0,27) 11,0 (0,24) 23,3 (0,52) (0,89)
19 29,8 7,5. (0:25) car 7,2. (0525) 17,4 (0,58) (1,0 )
2 32,5 9,0 (0,28) 9,0 (0,28) 16,5 (0,51) (1,0 )
20 55,0 16,0 (0,29) 15,0 (0,27) 27,0 (0,49) (0,94)
23 21,3 6,5 (0,31) 6,5 (0,31) 10,0 (0,47) (1,0 )
21 18,2 6,5 (0,36) 6,5 (0,36) 8,5 (0,47) (1,0 )
24 39,5 12,0 (0,30) 11,5 (0,29) 20,0 (0,51) (0,96)
28 36,0 = 10,5 (0,29) 18,0 (0,50) (0,96)

Beschreibung: Die Gehäuse sind flach-scheiben-
förmig, evolut und von serpentikoner Gestalt. Der Win-
dungsquerschnitt ist rund bis leicht oval, wobei die kon-
kave Windungszone nicht ganz ein Viertel der Windungs-
höhe ausmacht. Die Flanken sind deutlich abgeflacht,
knicken an der Nabelkante in steile Nabelflächen um. Die
Externfläche ist breitgerundert.

Abb. 13: Dactylioceras (Orthodactylites) directum
(BUCKMANN, 1926); Quebrada Chanchoquin;
B. St. M. 1978 II 14; nat. Gr.

Die Rippen setzen schon auf der Nabelfläche ein, errei-
chen ihre volle Stärke erst oberhalb der Nabelkante und
verlaufen rectoradiat bis leicht proradiat über Flanken und
Externfläche. Die Rippen sind sehr scharf und stehen rela-
tiv dicht (Exemplar Nr. 14 besitzt auf dem letzten Um-
gang ca. 30 Flanken- und ca. 60 Externrippen, auf dem
vorletzten halben Umgang 25 Flankenrippen; Nr. 19 auf
dem letzten Umgang 40 Flanken-, auf dem vorletzten
Umgang ca. 31 Flankenrippen). Die Interkostalräume
sind etwa doppelt so breit wie die Rippen. Die Externrip-

pen sind nur wenig schwächer als die Flankenrippen aus-
gebildet. An den Rippenspaltpunkten lassen sich keine
Verdickungen, nur manchmal schwache Knötchen beob-
achten. Die Rippenspaltpunkte liegen auf einer Linie, und
zwar noch auf der Flanke. Das Nabelband der äußeren,
nicht erhaltenen Windung (Exemplar Nr. 14) liegt auf den
Externrippen und läßt daher Rippenspaltpunkte wie
Flankenrippen frei. Die Art der Rippengabelung ist etwas
unregelmäßig, wobei jedoch die dichotome Rippengabe-
lung (d. h. die Aufteilung in zwei gleichwertige Extern-
rippen) überwiegt. Untergeordnet treten auch Einfach-
rippen auf, die mit zwei Schaltrippen gekoppelt sind.
Deutliche ontogenetische Merkmalsänderungen sind we-
der im Gehäusebau noch in der Skulptur zu erkennen.

Lobenlinien sind nicht sichtbar. Bei einer Windungs-
höhe von 12,1 mm besitzt der Sipho einen Durchmesser
von 1,1 mm.

Vergleich: Obwohl die Exemplare der vier verschie-
denen Lokalitäten sehr unterschiedlich erhalten sind, be-
reitet ihre artliche Zuordnung zu Dactylioceras (Ortho-
dactylites) directum keine Schwierigkeiten. Dies liegt
wohl daran, daß diese Art während der Ontogenese kaum
Wachstumsänderungen aufweist und auch, daß es sich um
eine überhaupt wenig variable Art handelt. Das Exemplar
Nr. 14, Durchmesser ursprünglich mindestens 55 bis
60 mm, stimmt besonders gut mit dem Holotypus
(Durchmesser 66 mm) überein. Doch treten auch beim
übrigen Material nur wenige Abweichungen auf. Subspe-
zifische Unterschiede sind jedoch nicht zu erkennen.

Bemerkungen: Da Dactylioceras (Orthodactylites)
directum - der auch stratigraphisch älteste Orthodactyli-
tes — morphologische Übergänge zu Dactylioceras (Eo-
dactylites) simplex erkennen läßt, ist eine phylogenetische

Ableitung von ähnlichen Eodactylites-Formen wahr-
scheinlich (Schmipr-Erring 1972: 172). Daß bis heute
keine angemessene Beschreibung dieser so wichtigen Art
aus dem englischen Typusgebiet vorliegt, nur eine eigen-
artige Buckmansche Kurzbeschreibung (1926) und Abbil-
dung, ist sehr bedauerlich.

Verbreitung: Dactylioceras (Orthodactylites) direc-
tum ist ein charakteristisches Element des nordwesteuro-
päischen Unter-Toarciums, das hiermit zum ersten Mal
aus Südamerika, wie überhaupt aus der pazifischen Pro-
vinz (SCHMIDT-ErrinG 1972: 162-163), beschrieben wird.
Doch scheint diese Art auch in der mediterranen Provinz
nicht selten zu sein. Unter Beachtung der unterschiedli-
chen, die Morphologie beeinflussenden Fossilisationsar-
ten (vgl. Abschnitt „Bemerkungen“ bei Dactylioceras an-
guinum) dürfte Dactylioceras annulatiforme mit zahlrei-
chen Subspezies (z. B. Kortek 1966: 127-130) und zahl-
reiche Formen, die Pınna & Levı-Setrti (1972) zu Meso-
dactylites und Nodicoeloceras stellen, mit Dactylioceras
directum synonym sein oder doch wenigstens sehr nahe
stehen.

3.1.2.3 Dactylioceras (?Orthodactylites) helianthoides
YokoYaMA, 1904
Taf. 1, Fig. 12-18, Taf. 2, Fig. 4; Abb. 14, 16e

1904 Dactylioceras helianthoides YOKOYAMA — YOKOYAMA:
16-17, Taf. 4, Fig. 4-6.
1964 Dactylioceras sp. - FREBOLD: 11, Taf. 5, Fig. 7-8.

1971 Dactylioceras (Dactylioceras) helianthoides YOKOYAMA —
HIRANO: 104-108, Taf. 14, Fig. 1-10.
?1971 Nodicoeloceras sp. - PINNA & LEVI-SETTI: Taf. 5, Fig. 3.

Material: a) Quebrada Noria, 700 mSSW Punkt 3132
(südlich Salto de la Muerte), (Abb. 1, Profil 12; Abb. 8,
Schicht 4), topographische Karte 1:100000, Blatta Car-
rera Pinto: x = 426,5 km, y = 6970,6 km. Zwanzig
Exemplare (B. St. M. 1978 II 29-48) in ziemlich vollstän-
diger Erhaltung als teilweise frühdiagenetisch verdrückte
Steinkerne großteils mit erhaltener Schale. Exemplare
Nr. 30 und Nr. 38 mit im wesentlichen vollständiger
Wohnkammer, Nr. 37 schließt mit 40,5 mm Durchmes-
ser noch im Bereich des Phragmokons ab.

b) Quebrada El Asiento (Abb. 2, Profil 3; Abb. 3,
Schicht 4), topographische Karte 1:100000, Blatt Potre-
rillos: x = 467,5 km, y = 7070,45 km. Drei Exemplare
(B. St. M. 1978 II 49-51) von Steinkernfragmenten.

c) Rio Manflas, Profil 2,5 km südlich Los Graneros,
zwischen dem Fluß und dem Cerro Salto del Toro
(Abb. 1, Profil 18; Abb. 9), (69°58,5’ Länge, 28°19,7’
Breite). Fin Exemplar (B. St. M. 1978 II 52) eines sehr
unvollständigen Steinkerns. Im Liegenden tritt Dactylio-
ceras (Orthodactylites) tenuicostatum chilense auf.

d) Quebrada El.Penon (Abb. 1, Profil 5b; Abb. 3a),
topographische Karte 1:100000, Blatt Laguna del Negro
Francisco: x = 473,7 km, y = 7007,5 km. 1 Steinkern-
exemplar (B. St. M. 1978 II 232) zusammen mit häufig
Dact. (Orthodactylites) tenuicostatum chilense.

Maße (in mm):

Nr. DM WH WB NW WB/WH
38 60,0 ca. 18,0 (0,28) = 27,5 (0,46) er

30 46,0 16,0 (0,35) ca. 17,0 (0537) 20,5 (0,45) (1,06)
37 40,5 13,5 , (0,33) 13,5 (0,33) 17,5 (0,43) 1,0 )
32 34,0 10,5 (0,31) ca. 12,0 (0,35) 16,5 (0,49) 1,14)
31 ca. 31 en 13,5 (0,44) 12,0 (0,39) =

33 30,0 10,5 (0,35) 14,0. (0,47) 12,0 (0,4 ) (1,33)
47 29,0 9,0 (0,31) 8,0 (0,28) 12,5 (0,26) (0,89)
34 29,5 9,2 (0,32) 11,0 (0,37) 12,0 (0,41) (1,16)
4 27,0 9,0 (0,33) 11,0 (0,41) 11,5 (0,43) (1,22)
42 22,5 7,0 (0,31) = 11,0 (0,49) ei

43 21,5 8,0 (0,37) 10,0 (0,47) 9,0 (0,42) (1,25)

Beschreibung: Recht weitgenabelte Formen mit Steinkern nur eine reliefarme, breit-rundliche Rippenspur

rundlichem bis quer ovalem Windungsquerschnitt, wobei
sich die Windungen etwa '/, übergreifen. Die Externseite
ist breit gerundet und geht ebenfalls in gerundete, bei
manchen Exemplaren auch etwas abgeflachte Flanken
über. Eine Nabelkante ist bei einigen Exemplaren über-
haupt nicht, bei manchen nur schwach ausgebildet. Die
Nabelfläche fällt steil gerundet zur Naht ab.

Die Rippen verlaufen von der Naht über Flanken und
Externseite rectoradiat, sind sehr scharf und hoch (bei Fx-
emplar Nr. 38 bis über 1 mm), was jedoch nur beı
Schalenerhaltung deutlich zu beobachten ist. Es sind Voll-
rippen. Sie sind massiv und lassen nach Ablösen auf dem

zurück. Die Externrippen sind kaum weniger kräftig als
die Flankenrippen ausgebildet. Die Rippendichte ist an
den einzelnen Exemplaren verschieden (z. B. besitzt Ex-
emplar 38 bei 60 mm Durchmesser 41 Flankenrippen auf
dem letzten Umgang, Exemplar 30 dagegen bei 46 mm
Durchmesser 55 Flankenrippen). Die Rippenspaltpunkte
sind sehr unregelmäßig ausgebildet, was sowohl die Lage,
die Form und die Art der Rippenspaltung betrifft. Meist
gabeln die Flankenrippen in zwei, nicht selten auch in drei
Externrippen. Auch treten Einfachrippen auf, neben die
sich auf der Externseite Schaltrippen gesellen können,
ohne daß überhaupt ein Rippenspaltpunkt ausgebildet ist.

In Abständen von 4 bis 10 Flankenrippen können die
Rippenspaltpunkte zu kräftigen Dornen ausgebildet sein,
die die Rippen um bis zu 2 mm überragen. An solchen
Stellen treten manchmal auch fibulate Flankenrippen, wie

DM
60

40 |

50 _

40 | o

30 | ,

T T T T T

5 10 15 20 25 mm NW

Abb. 14:

auch Aufspaltung in drei Externrippen auf. Die Rippen-
spaltpunkte der Innenwindungen liegen meist frei, sind
also nicht von der nächstfolgenden Windung überdeckt.

DM
80

50 |

Dactylioceras (?Orthodactylites) helianthoides YOKOYAMA, 1904; Werte der Windungshöhe,

der Windungsbreite und der Nabelweite im Verhältnis zum Durchmesser (vgl. Tabelle).

Analysierbare Lobenlinien treten nicht auf.

Während der Ontogenese machen sich, abgesehen von
der allgemeinen großen Variabilität, keine besonderen
Entwicklungstendenzen bemerkbar.

Vergleich: Trotz dieser ausgeprägten Variabilität im
einzelnen, erscheint diese Formengruppe eine gute Art zu
bilden. Möglicherweise handelt es sich bei den großen
Exemplaren (z. B. bei Nr. 38, 37, 30 und 35) um Makro-
konche, bei den kleinen um Mikrokonche. Die Überein-
stimmung der Formen von Quebrada Noria mit der Be-
schreibung und den Abbildungen von Dactylioceras he-
lianthoides bei Hırano (1971) ist bemerkenswert gut. Das
Material von Rio Manflas und Quebrada EI Asiento läßt
sich wegen ungenügender Erhaltung nur als Dactylioceras
cf. helianthoides bestimmen.

Bemerkungen: Aufgrund der älteren Literatur war
die richtige Bestimmung dieser Art nicht möglich. Erst
Hırano (1971) hat eine präzise und ausführliche Beschrei-
bung und Bearbeitung geliefert. Dabei hat sich gezeigt,

daß sämtliche aus Europa stammenden Exemplare, die zu
dieser Art gestellt worden waren und mit Abbildungen
veröffentlicht sind, nicht dieser Art angehören
(SCHMIDT-EFFInG 1972: 110). Nur in Pınna & Levi-SetTi
(1971: Taf. 5, Fig. 3) ist ein Exemplar als Nodicoeloceras
sp. abgebildet, das dieser Art zugeordnet werden könnte
(vgl. z. B. Hırano 1971: Taf. 14, Fig. 6).

Nach dem Gesamtbild zu urteilen, gehört Dactylioceras
helianthoides sicherlich zu Orthodactylites. Besonders
rundliche und bedornte Exemplare ließen jedoch auch an
eine Zuordnung zu Nodicoeloceras denken. Warum
Hirano (1971: 104) diese Art der Untergattung Dactylio-
ceras zuordnet, was nicht nur der morphologischen, son-
dern auch der stratigraphischen Stellung widerspricht,

bleibt unklar.

Verbreitung: Es handelt sich um eine, besonders für
den pazifischen Raum (Japan, Kanada und Chile) charak-
teristische Art — in Japan ist es sogar die einzige bekannte
Dactylioceras-Art —, wobei besonders erstaunlich ist, daß

sie aus dem relativ nahen Östsibirien trotz des guten Bear-
beitungszustandes (z. B. Dacıs 1968 und Krymcoız
1974 a) nicht bekannt ist. Nach Hırano (1973:55 u. 58) ist
Dactylioceras helianthoides in Japan vom Domerium (zu-
sammen mit Amaltheus cf. stokesi) bis in die untere falci-
fer-Zone (zusammen mit Harpoceras aff. exaratum) ver-
breitet. Die chilenischen Funde sind aufgrund der Begleit-
fauna in das höhere Unter-Toarcium (hoelderi-Zone) zu
stellen.

3.1.2.4 Dactylioceras (Orthodactylites) hoelderi n. sp.
Laf..2, Fig. 13,5; Abb. 15, 16h, i

Holotyp: Taf. 2, Fig. la, b (B. St. M. 1978 II 53).
Ziemlich vollständiger Steinkern mit erhaltener Schale.

Derivatio nominis: Zu Ehren von Herrn Prof. Dr.
H. HöuLper, Münster/Westfalen, der sich um die interna-
tionale Jura-Forschung sehr verdient gemacht hat.

Locus typicus: a) Quebrada Yerbas Buenas (Chile,
Provinz Atacama), (Abb. 1, Profil 9; Abb. 6, Schicht 6),
topographische Karte 1:100000, Blatt Carrera Pinto: x =
439,4 km; y = 6979,3 km.

Stratum typicum: Etwa 1 m mächtige Schichtfolge
mit bis 20 cm mächtigen Kalkbänken, die auch Dactylio-
ceras (Orthodactylites) directum enthalten. Im Liegenden
Kalkschiefer mit Pectinula cancellata Leanza und Kalke
mit Radstockiceras sp. 2. Direkt im Hangenden 2 bis3 m
mächtige, ca. 10 cm gebankte, rostig anwitternde Kalke
mit Mergelzwischenlagen. Oberste (oder vorletzte) Bank
mit Nodicoeloceras cf. crassoides (Simpson) Form A, Hil-

Maße (in mm):

daites cf. serpentiniformis (Buckman), H. cf. serpentinus
(REINECKE), Harpoceratoides cf. alternatus (Simpson) und
Polyplectus sp. Höheres Unter-Toarcium, hoelderi-Zone.

Diagnose: Es handelt sich um eine neue Art von Dac-
tylioceras (Orthodactylites) mit hochovalem Windungs-
querschnitt, wobei die Windungsbreite an der Nabelkante
am größten ist und mit Rippen, die an der Naht in voller
Stärke einsetzen und hoch auf den Flanken in zwei bis drei
Externrippen gabeln. Die Rippen sind leicht geschwungen
und gabeln an etwas unregelmäßig gelegenen Rippen-
spaltpunkten auf. Auf den inneren Windungen, bis etwa
25 mm Durchmesser, treten gelegentlich auch fibulate
Rippen auf, wobei die Rippenspaltpunkte Knötchen tra-
gen und 3 bis 4 Externrippen von diesen abspalten.

Material: a) Locus typicus: Holotypus und vier wei-
tere Exemplare (Nr. 54: Erhaltung nur der inneren Win-
dungen, von Serpeln überwachsen; Exemplar Nr. 55:
Fragment der inneren Windungen; B. St. M. 1978 II
56-57). Erhaltung wie Holotypus.

b) Quebrada Calquis (Abb. 1, Profil 15), topographi-
sche Karte 1:100000, Blatt La Guardia: x = 402,5 km,
y = 6909,5 km. Zwei Exemplare (B. St.M. 1978 II
58-59), zusammen mit Nodicoeloceras cf. crassoides
(Sımpson) Form A, Hıildaites sp. und Polyplectus sp.

c) Quebrada Noria, 700 m SSW Punkt 3132 (südlich
Salto de la Muerte), (Abb. 1, Profil 12; Abb. 8,
Schicht 4), topographische Karte 1:100 000, Blatt Car-
rera Pinto: x = 426,5 km, y = 6970,6 km. Ein Exemplar
(B. St. M. 1978 II 60) Dactylioceras (? Orthodactylites)
helianthoides aufsitzend.

Nr. DM WH WB NW WB/WH
53 49,3 15,5 (0,31) 13,5 (0,27) 22,2 (0,45) (0,87)
53 ca. 40 13,7 (0,34) ca. 12,5 (0,31) 16,5 (0,41) (0,90)
54 27,6 10,1 (0,36) 9,3 (0,33) 10,5 (0,38) (0,92)
56 26,0 10,0 (0,38) ca. 8,5 (0,33) 9,0 (0,35) (0,85)

Beschreibung des Holotypus: Flachscheibiges,
mäßig evolutes, hochmündiges Gehäuse mit flach einge-
senktem Nabel, wobei mindestens 5 Umgänge zu erken-

nen sind. Der äußere Umgang entspricht im wesentlichen
der Wohnkammer, wobei nur etwa 1 cm der Wohnkam-
merlänge im Mündungsbereich zu fehlen scheint.

Der Windungsquerschnitt ist ausgeprägt hochoval im
Wohnkammerbereich, innen etwas rundlicher. Die größte
Windungsbreite wird in der unmittelbaren Nähe der Na-
belkante erreicht. Die flachen, breiten Flanken fallen da-
her leicht zur Externseite hin ein. Eine Externkante fehlt,
die Nabelkante ist scharf ausgebildet. Die Nabelfläche ist
steil, die Externfläche schmal. Die konkave Windungs-
zone beträgt etwa '/, des Umganges. Die Windungszu-
nahme (WH, WB und NW) während der Ontogenese er-
folgt sehr gleichmäßig.

Abb. 15: Dactylioceras (Orthodactylites) hoelderi n. sp., Holo-
typus, Quebrada Yerbas Buenas; B. St. M. 1978 II 53; nat. Gr.

Die Flankenrippen beginnen unmittelbar an der Naht
und verlaufen proradiat und etwas geschwungen über Na-
belfläche und inneren Flankenbereich, wobei sie von An-
fang an in voller Stärke ausgebildet sind. Die Flankenrip-
pen sind scharf, relativ feın und stehen dicht (letzter Um-
gang mit 60, vorletzter Umgang mit etwa 43 Flankenrip-
pen). Die Rippenspaltpunkte sind unverdickt, befinden
sich ungewöhnlich hoch auf den Flanken und liegen unre-
gelmäßig, also nicht auf einer geraden Linie. Unter sehr
spitzem Winkel spalten an den Rippenspaltpunkten 2 bis 3
Externrippen, im einzelnen etwas unregelmäßig ab. Die
Externrippen sind in ihrer Ausbildung und in ihrem Ver-
lauf den Flankenrippen ähnlich.

Lobenlinien sind nicht sichtbar.

Vergleich: Die Paratypen stimmen bis auf Exemplar
Nr. 57, das in Querschnitt und Rippengabelung etwas
abweicht, gut mit dem Holotyp überein. Bei ihnen sind
die inneren Windungsbereiche jedoch günstiger sichtbar
als beim Holotyp, weshalb einige wichtige Beobachtun-
gen ergänzt werden können: Aufden inneren Windungen,
bis zu einem Durchmesser von etwa 25 mm, treten neben
den vorherrschenden einfachen Flankenrippen gelegent-
lich auch fibulate Rippen auf (bei Exemplar Nr. 56 entfal-
len auf erwa 8 Flankenrippen jeweils 2, die fibulat ım Rip-
penspaltpunkt zusammenlaufen). Diese tragen Knötchen
und spalten in 3 bis 4 Externrippen auf.

Die beiden Exemplare von der Quebrada Calquis sind
nicht so gut erhalten, daß ihre Zuordnung völlig gesichert
wäre.

Vergleich mit ähnlichen Arten: Dactylioceras
hoelderi läßt morphologische Beziehungen zu Dactylio-
ceras semicelatum (SCHMIDT-ErrinG 1972: 95), zu Dacty-
lioceras hispanum (SCHMiDT-ErrinG 1972: 102) und zu
Dactylioceras helianthoides (vgl. S. 36) erkennen. Die
neue Art ist jedoch dichter berippt, zeigt unregelmäßigere
Rippengabelung und besitzt durch die Art der Rippenga-
belung wesentlich mehr Externrippen als Dactylioceras
semicelatum. Auch sind die Rippen leicht geschwungen.
Dactylioceras hispanum ist wesentlich lockerer berippt
und besitzt außerdem gerade Rippen. Dactylioceras he-
lianthoides weicht durch einen rundlicheren Windungs-
querschnitt und eine in vielen Merkmalen wesentlich un-
regelmäßigere Berippung ab.

Bemerkungen: Da Formen, die zu Dactylioceras
hoelderi zu stellen wären, bisher aus der Literatur nicht
bekannt sind, wird angenommen, daß es sich um eine Art
handelt, die in Chile und den umgebenden Räumen des
südöstlichen Pazifiks und Südamerikas endemisch ist.

Verbreitung: Höheres Unter-Toarcium (hoelderi-
Zone) von Chile.

3.1.2.5 Dactylioceras (Orthodactylites) tennicostatum
chilense n. ssp.
Taf. 2, Fig. 6-8; Abb. 16g

Holotypus: Taf. 2, Fig. 6a, b (B. St. M. 1978 II 61)
Steinkern der Wohnkammer, Innenwindungen weitge-

hend verdeckt.

Derivatio nominis: Nach dem Vorkommen in Chi-
le.

Locus typicus: Rio Manflas (Departamento Copia-
pö, Provinz Atacama), Profil 2,5 km südlich Los Grane-
ros, zwischen dem Fluß und dem Cerro Salto del Toro
(69°58,5’ Länge, 28°19,7’ Breite), (Abb. 1, Profil 18,
Abb. 9).

Stratum typicum: Aus dem hangenden Teil einer -
Serie 10 bis 30 cm mächtiger, gut gebankter, dichter Kal-
ke, die mit bis zu 1,5 m mächtigen Mergellagen wechsella-
gern. Zum Hangenden hin Mergel geringermächtig und
mehr Kalkbänke. Ammoniten sehr selten. Übergehend in
eine Serie gebankter Sandsteine, die zunächst noch mit
Mergeln wechsellagern (Brachiopoden und Weyla sp.
häufig).

Etwa 30 m im Liegenden 2 bis3 m mächtige, feinschich-

tige bis schiefrige, sandige Kalke mit Pectinula cancellata
Leanza und Radstockiceras sp.

tenuicostatum-Zone, sehr wahr-

scheinlich höherer Abschnitt dieser Zone.

Unter-Toarcıum,

Diagnose: Die neue Unterart unterscheidet sich von
der Typus-Art durch den Besitz von Knötchen, die im Be-
reich der Rippenspaltpunkte in Abständen auftreten. Be-
sonders deutlich sind diese Knötchen auf den Innenwin-
dungen ausgebildet; sie sind jedoch auch noch auf dem
letztem Umgang (Wohnkammer) zu beobachten.

Material: a) Locus typicus: Ein Exemplar (Holoty-
pus): Steinkern aus tonreichem, dunklem Kalk, der diage-
netisch teilweise verdrückt ist. Erhalten ist der äußere
Umgang, der wohl der Wohnkammer eines adulten Ge-
häuses entspricht.

b) Rio Manflas, Profil zwischen dem Rio Manflas und
dem Portezuelo El Padre (70°0,9’ Länge, 28°11,8’ Breite),
(Abb. 1, Profil 16). Ein schlecht erhaltenes Windungs-
fragment (B. St. M. 1978 II 62).

c) Quebrada EI Bolito (Abb. 1, Profil 7; Abb. 5,
Schicht 5), topographische Karte 1:100000, Blatt Laguna
del Negro Francisco: x = 458,4 km, y = 6995,5 km. Vier
kalkige, z. T. limonitisierte Steinkern-Fragmente z. T.
mit Schalenerhaltung verschiedener Windungsabschnitte
(B. St. M. 1978 II 63-66).

d) Quebrada La Chaucha (Abb. 1., Profil 5a), topogra-
phische Karte 1:100000, Blatt Laguna del Negro Francis-
co: x = 468 km, y = 7011 km. Zwei kalkig-mergelige
Steinkern-Fragmente (B. St. M. 1978 II 67-68), nicht aus
dem Anstehenden entnommen, wahrscheinlich zusam-
men mit einem Fragment von Dactylioceras (Orthodacty-

lites) cf. directum (Exemplar Nr. 69) und Dactylioceras
(Orthodactylites) sp. (Exemplar Nr. 70, juvenil, Durch-
messer 12 mm).

e) Quebrada El Penon (Abb. 1, Profil 5b; Abb. 3a), to-
pographische Karte 1:100000, Blatt Laguna del Negro
Francisco: x = 473,7km y = 7007,5 km. Schicht 6
7 Steinkerne (B. St. M. 1978 II 212-218 zusammen mit
sehr selten Dact. (Orthodactylites) helianthoides und
Schicht 7 3 Steinkernexemplare (B. St. M. 1978 II
219-221).

Maße: Der Holotyp besitzt einen Durchmesser
(= Enddurchmesser) von etwa 125 mm, Exemplar Nr. 63
etwa 86 mm, Exemplar Nr. 64 mindestens 90 mm, Ex-
emplar Nr. 65 etwa 41 mm und Exemplar Nr. 68 =
67 mm Durchmesser.

Beschreibung: Sehr evolutes, serpentikones,
flachscheibiges Gehäuse, das durch eine besonders lang-
same und konstante Windungszunahme auffällt. Die Zahl
der Umgänge ist am vorliegenden Material nicht feststell-
bar. Der Windungsquerschnitt ist hoch oval bis rundlich,
die Nabelfläche steil; die konkave Windungszone ist nur
gering ausgebildet.

Die Rippen sind fein und stehen dicht - der Holotypus
besitzt etwa 120 Flankenrippen auf dem letzten Umgang
-; sie entspringen auf der Nabelfläche, verlaufen leicht
proradiat über die Flanken, spalten teilweise am Außen-
bug auf und verlaufen in ähnlicher Stärke und Richtung
über die Externfläche. Die Form der Gabelung ist unre-
gelmäßig, am vorliegenden Material im einzelnen nicht
gut zu beobachten. Auf den Innenwindungen (z. B. Ex-
emplar von Quebrada El Bolito) ist die Skulptur kräftiger
als auf der Wohnkammer. Im Mündungsbereich, z. B.
beim Holotypus, fällt die große Zahl der Einfachrippen
auf, die außerdem leicht geschwungen und nach vorne et-
was ausgezogen sind. Der Schalenbau, wie auch die Ver-
teilung der verschiedenen Rippentypen (normale Vollrip-
pen auf den Innenwindungen, von Schalensubstanz er-
füllte Rippen auf dem hinteren Teil der Wohnkammer,
wieder normale Vollrippen auf dem vorderen Teil der
Wohnkammer) entspricht im wesentlichen den Beobach-
tungen von SCHMIDT-EFFING (1972: 27) und LEHMANN
(1975).

Als besonderes Merkmal ist jedoch hervorzuheben, daß
auf allen Windungsabschnitten im Bereich der Rippen-
spaltpunkte in Abständen von 3 bis 10 Flankenrippen, auf
den Innenwindungen dichter, auf den äußeren Windun-
gen in größeren Abständen, Knötchen auftreten. Ein di-
rekter Zusammenhang von Berippungsmuster/Rippen-
spaltpunkt und Knötchen ist nicht immer feststellbar,
d. h., die Knötchen können auch neben den Rippenspalt-
punkten sitzen. Auf den Steinkern-Innenwindungen zei-
gen die Knötchen Relief (z. B. Exemplar Nr. 63), sind
also Voll-Knötchen, auf den Außenwindungen nur flache
Erhebungen, die möglicherweise als Basis von Hohl-
Knötchen zu deuten sind.

Lobenlinien sind nicht erhalten.

Vergleich: Die vorliegenden Formen stimmen unter-
einander gut überein. Lediglich Exemplar Nr. 68 weicht
insofern etwas ab, als hier die Knötchen kräftiger ausge-
bildet sind und außerdem Rippenbündel auftreten, wie sie
etwa von Prodactylioceras bekannt sind.

Vergleich mit der Typus-Art: Von den Knötchen
abgesehen, stimmt das vorliegende Material gut mit dem
Neotypus der Typusart aus Yorkshire überein. Der Holo-
typ der Unterart fällt durch seine besondere Größe - Dac-
tylioceras tennicostatum ist nur selten größer als 10 cm —
auf. Sehr bemerkenswert sind die Knötchen, ein Merk-
mal, das bisher noch nicht von dieser Art beschrieben
wurde und das eine subspezifische Abtrennung rechtfer-
ugt.

Bemerkungen: Die beschriebene Unterart unter-
scheidet sich von Dactylioceras tenuicostatum nur durch
den Besitz von Knötchen (Schmipr-Erring 1975: 80). Die-
ses Merkmal läßt taxonomisch, je nach dem Gewicht, das
man ihm zubilligt, verschiedene Interpretationen zu.
Folgt man den Arbeiten von Guzx (1971, 1973 b), so wä-
ren diese Formen als neue Art der von ihm aufgestellten
Gattung Rakusites oder, da Knötchen auch untergeord-
net auf den Altersstadien auftreten, zu einer neuen Art
von Porpoceras zu stellen. Das Merkmal ‚‚Knötchen“
(„espines‘“) ist in der Dactylioceraten-Systematik von
Gurx von übergeordneter Bedeutung (vgl. SCHMiDT-Er-
FING 1975).

Da es sich bei den beknoteten Orthodactyliten der te-
nutcostatum-Zone bisher meist um Einzelfunde gehandelt
hat, wobei ihre morphologische Beziehung zu bekannten
Arten immer offenkundig war, sehe ich darin eher eine Pa-
rallelität zu dem Phänomen der fastigaten Ceratiten des
germanischen Muschelkalkes (WEnGer 1957, ROTHE
1955). Auch diese lassen sich einwandfrei bei bekannten
Ceratiten-Arten einordnen, unterscheiden sich jedoch
von diesen in einem markanten Merkmal, nämlich den die
Externfläche ohne Unterbrechung querenden Ringrip-
pen.

So wıe ım Fall der fastigaten Muschelkalk-Ceratiten
neue Merkmale zeitlich verfrüht in Einzelindividuen, in
Populationen oder Rassenkreisen ihren Ausdruck finden
können, mag auch das Auftreten von beknoteten Ortho-
dactyliten in der tennicostatum-Zone zu erklären sein. Im
Fall der Muschelkalk-Formen kam das neue Merkmal aus
paläogeographischen Gründen nicht zum Durchbruch,
entspricht aber vollkommen der üblichen morphogeneti-
schen Reihenfolge im Sinne von WepekınD. Im Fall der
weltweit verbreiteten Dactylioceraten kam dieses Merk-
mal im höheren Unter-Toarcium jedoch zur Entfaltung.

In diesem Zusammenhang kann angeführt werden, daß
Pınna & Levi-Serti (1971) aus Formen der Dactylioceras
(Orthodactylites)-Gruppe in der falcıfer-Zone die durch
Knötchen charakterisierte und im Mediterran weit ver-
breitete Gattung Mesodactylites ableiten. Ähnliche Knöt-

chen sind es auch, die bei Dactylioceras tennicostatum chi-
lense auftreten. Auch das durch Knötchen charakteri-
sierte Nodicoeloceras wird von verschiedenen Bearbeitern
(HowarTH 1962, Pınna & Levi-Setti 1971, SCHMIDT-EF-
FING 1972) aus der Gruppe des Dactylioceras (Orthodacty-
lites) abgeleitet.

Diesen Sachverhalt möchte ich in folgender Weise in-
terpretieren: In der tenuicostatum-Zone deutet sich bei
verschiedenen Arten von Dactylioceras (Orthodactylites)
eine Entwicklung neuer Merkmale an — im Fall der be-
schriebenen chilenischen Form dürfte es sich um eine geo-
graphische Rasse handeln -, die dann bei weiteren Verän-
derungen eine Aufspaltung in verschiedene Arten und
Gattungen zuläßt. Im Artbereich sollte jedoch eine taxo-
nomische Abtrennung von der Mutterart erst dann erfol-
gen, wenn sich beide durch wenigstens zwei markante und
gut definierbare artspezifische Merkmale unterscheiden
(SCHMIDT-ErFinG 1972: 32). Die Knötchen stellen zu-
nächst nur ein markantes Merkmal dar, das eine artliche
Abtrennung bei verantwortlicher Anwendung des Art-
Begriffes (Mayr 1967) nicht erlauben kann, so einfach es
zweifellos wäre, die Dactylioceraten-Gattungen schema-
tisch in solche mit und solche ohne Knötchen einzuteilen.
Aus diesem Grund ist die beschriebene Form nur als Un-
terart von Dactylioceras tenuicostatum klassifiziert. Ent-
sprechend könnte auch Rakusites pruddeni, um auf das
eingangs gewählte Beispiel zurückzukommen, als Dacty-
lioceras (Orthodactylites) directum pruddeni eingestuft
werden.

Verbreitung: Durch Vergleich mit dem stratigraphi-
schen Auftreten der Typus-Art in NW-Europa und der
chilenischen Gesamtfauna gehört Dactylioceras (Ortho-
dactylites) tennicostatum chilense dem höheren Abschnitt
der tenuicostatum-Zone (tennicostatum-Subzone) an.

3.1.2.6 Dactylioceras (Orthodactylites) sp.

Aus dem Profil vom Rio Manflas liegen zwei kleine
Fragmente vor (B. St. M. 1978 II 71-72), die wegen zu
unvollständiger Erhaltung artlich nicht bestimmbar sind.

3.1.3 Subgenus: Dactylioceras (Dactylioceras)
Hyatt, 1867

Typus-Art: Dactylioceras communis (]. SOWERBY,
1815)

Diagnose: vgl. SchmiDT-Erring 1972: 59.

Verbreitung: Vertreter dieser Untergattung sind aus
Chile und auch aus dem restlichen Südamerika bis jetzt
unbekannt. Ihr Hauptverbreitungsgebiet ist die nord-
westeuropäische und die boreale Faunenprovinz. Im Me-
diterran werden Formen dieser Untergattung relativ selten
und nur in wenigen Arten angetroffen.

Selten im höheren Unter-Toarcium, häufig im Mittel-
Toarcıum (commune-Subzone).

3.2 GENUS: NODICOELOCERAS BUCKMAN,

1926

Typus-Art: Ammonites crassoides Sımpson, 1855

Diagnose: (ausführliche Charakteristik und Syno-
nymie des Genus und seiner Arten in SCHMIDT-EFFING
1972: 63-66): Dickscheibige Vertreter der Familie Dacty-
lioceratidae mit breit ovalem, im Bereich der Innenwin-
dungen sehr breit ovalem bis kadikonem Windungsquer-
schnitt. Kräftige annulare Rippenskulptur, ähnlich wie
bei Orthodactylites. Die Rippenspaltpunkte sind oft mit
Dörnchen oder Knötchen besetzt; auch fibulate Rippen
treten gelegentlich auf. In vielen Merkmalen werden wäh-
rend der Ontogenese ausgeprägte Wachstumsallometrien
beobachtet.

Bemerkungen: Auch HowartH (1978: 256) gab
jüngst eine Diagnose dieser Gattung, die mit der hier vor-
gelegten in allen wichtigen Punkten zwar übereinstimmt,
in der Praxis sich jedoch darin unterscheidet, daß er die
von SCHMIDT-EFFInG (1972) und anderen Autoren erkann-
ten Nodicoeloceras-Formen der tenuicostatum-Zone zu
Dactylioceras (Orthodactylites) stellt. Beide Wege sind
zwar gangbar, doch halte ich die Zuordnung auch der älte-
ren Formen mit breit ovalem Windungsquerschnitt und
ausgeprägten Wachstumsallometrien, schon wegen ihrer
leichten Unterscheidbarkeit von Orthodactylites, für na-
türlicher und besser anwendbar.

Nodicoeloceras ist zwar eine sehr charakteristische und
daher leicht erkennbare Gattung; große Schwierigkeiten
bereiten dagegen, wegen des ausgeprägten ontogeneti-
schen Merkmalswechsels, die artliche Zuordnung nur
fragmentär erhaltener Exemplare. Auch durch die unter-
schiedlichen Erhaltungsweisen der hier stärker differen-
zierten Skulpturelemente -strukturen (z.B.
SCHMIDT-EFFinG 1972: 28) werden starke Unsicherheiten
in der artlichen Zuordnung verursacht.

Nach dem Versuch (ScHMiDT-Erring 1972: 63-66) über
die Taxonomie von Nodicoeloceras mehr Klarheit zu ge-
winnen, sind von HowarrH (1973, 1978) mehrere
Stellungnahmen zu den englischen Vertretern dieser Gat-
tung - die meisten ihrer Arten haben englische Typen - er-
schienen, die schwerwiegend sind. HOWARTH synony-
miert zahlreiche in England aufgestellte und dann in ande-
ren Ländern ebenfalls erkannte Nodicoeloceras-Arten,
wobei er, was sehr verwirrend ist, in seinen beiden Arbei-
ten auch durchaus unterschiedliche Standpunkte bezieht.
Das betrifft z. B. seine Stellungnahmen zu Nodicoeloceras
annulatum und die stark überkreuzenden Synonymie-
rungen von Nodicoeloceras crosbeyi (HOwARTH 1973: 255)
und Nodicoeloceras crassoides (HowarTH 1978: 256).

und

Wie heißen die außerhalb Englands gefundenen Arten,
die nach englischen Typen bestimmt sind, jetzt, nachdem
diese synonymiert wurden? Das erscheint als eine gro-
teske Frage, doch sind diese Formen in den meisten Fällen
durchaus nicht wie die englischen zu behandeln. Die Ur-

Abb. 16: Windungsquerschnitte, nat. Gr. a: Dactylioceras (Eodactylites) simplex Fucını, 1935; Que-
brada Chanchoquin; B. St. M. 1978 II 4. b: Dactylioceras (Eodactylites) simplex Fucını, 1935; Quebrada
Chanchoquin; B. St. M. 1978 II 7. c: Dactylioceras (Orthodactylites) anguinum (REINECKE, 1818); Que-
brada Chanchoquin; B. St. M. 1978 II 12. d: Dactylioceras (Orthodactylites) anguınum (REINECKE, 1818);
Quebrada Chanchoquin; B. St. M. 1978 II 13. e: Dactylioceras (?Orthodactylites) helianthoides Yo-
KOYAMA 1904; Quebrada Noria; B. St. M. 1978 1133. f: Dactylioceras (Orthodactylites) directum (BUCk-
MAN, 1926); Quebrada Chanchoquin; B. St. M. 1978 II 14. g: Dactylioceras (Orthodactylites) tenuicos-
tatum chilense n. sp., Quebrada La Chaucha; B. St. M. 1978 1168. h: Dactylioceras (Orthodactylites) hoel-
deri n. sp.; Quebrada Yerbas Buenas; B. St. M. 1978 II 57. i: Dactylioceras (Orthodactylites) hoelderi n.
sp.; Quebrada Yerbas Buenas; B. St. M. 1978 1156. j: Nodicoeloceras cf. psendosemicelatum (MAUBEUGE,
1957); Quebrada Chanchoquin; B. St. M. 1978 II 77. k: Nodicoeloceras cf. eikenbergi (HOFFMANN,
1968); Quebrada Chanchoquin; B. St. M. 1978 II 78. 1: Nodicoeloceras cf. crassoides (SımPsoN, 1855)
Form A; Quebrada Yerbas Buenas; B. St. M. 1978 II 79. m: Nodicoeloceras cf. crassoides (SIMPSON, 1855)
Form A; Quebrada Yerbas Buenas; B. St. M. 1978 II 82. n: Nodicoeloceras cf. crassoides (SIMPSON, 1855)
Form B; Quebrada El Asiento; B. St. M. 1978 II 84. o: Nodicoeloceras cf. crassoides (SIMPSON, 1855)
Form C; Quebrada El Asiento; B. St. M. 1978 II 85.

sache ist in der sehr frühen Aufstellung der englischen Ar-
ten bei ungenügender Abbildung und Beschreibung zu su-
chen, wobei offenbar dort von Anfang an ‚,splitters‘“ am
Werke waren, wie jetzt HowarTH entlarvt. Die Bearbeiter
nicht-englischen Materials erkannten unter Verwendung
dieser Namen in vielen Fällen gute Arten, die in die Litera-
tur nun schon seit langem eingeführt sind, wenn sie auch
den englischen Typen nicht entsprechen. Nodicoeloceras
annulatum ist da ein ganz besonders klassisches Beispiel.
Es ist seit Oppeı (1856) eine gute Art von großer Bedeu-
tung, doch kann Howartk (1973: 257) zeigen, daß der
völlig ungenügend abgebildete Lectotyp zu Nodicoeloce-
ras crassoides zu stellen ist.

Diese Arten müßten jetzt neu benannt werden. Um je-
doch weitere Verwirrungen zu vermeiden, kann dies nur
an einem umfangreichen Material von adulten Exemplaren
bei guter und möglichst vollständiger Erhaltung gesche-
hen. Das chilenische Material ist viel zu unvollständig und
außerdem so weit von den klassischen Lokalitäten ent-
fernt, daß eine Neubearbeitung in diesem Rahmen sehr
wenig sinnvoll erscheinen würde.

Da über die Zuordnung der Nodicoeloceras-Arten so
grundSitzliche Unklarheiten herrschen, können die hier
beschriebenen chilenischen Formen nur in offener No-
menklatur behandelt werden.

3.2.1 Nodicoeloceras cf. psendosemicelatum (MAUBEUGE,
1957)
Taf. 2, Fig. 9; Abb. 16)

cf. 1957 Dactylioceras psendosemicelatum nov. spec. — MAU-
BEUGE 1957: 193, Taf. 3, Fig. 6

Material: Quebrada Chanchoquin (Abb. 1, Profil 21;
Abb. 10, Schicht 4), topographische Karte 1:100000,
Blatt El Tränsito: x = 375,1 km, y = 6811,05 km. Profil-
beschreibung: siehe v. HıLıEsranpTt (1973: 353-354). Die
Dactylioceraten stammen aus dem tieferen Horizont, zu-
sammen mit sehr selten Radstockiceras sp. und Bouleice-
ras cf. chakdallaense Farmı. Fünf teilweise etwas ver-
drückte Exemplare (B. St. M. 1978 II 73-76) als Frag-
mente und B. St. M. 1978 II 77 als relativ komplettes
Stück. Die Schalenhohlräume sind teils von Sediment,
teils auch von Kalzit erfüllt, wobei die Schale verkieselt ist.
Der Sipho ist teilweise sichtbar.

Maße: Exemplar Nr. 77 besitzt 60 mm, Exemplar Nr.
73 46 mm und Exemplar Nr. 75 etwa 62 mm Durchmes-
ser.

Beschreibung: Weitgenabeltes, gedrungenes Ge-
häuse mit napfförmig eingesenktem Nabel. Der Win-
dungsquerschnitt ist ausgeprägt breit oval, gerundet. Da-
her fehlen Nabel- und Externkante, weshalb Nabel-,
Flanken- und Externfläche ohne deutliche Grenze inein-
ander übergehen.

Die Rippen verlaufen auf den Flanken annähernd recto-
radiat, auf der Externfläche stärker proklin. Sie sind auf

den inneren Windungen kräftiger ausgebildet als auf den
äußeren. Die Rippen sind relativ fein, teils auch etwas
kräftiger, schmal und stehen dicht - bei Exemplar Nr. 77
etwa 60 Flankenrippen auf dem letzten Umgang. Die Ex-
ternrippen sind meist etwas feiner als die Flankenrippen
ausgebildet. Die Rippenspaltpunkte sind auf den inneren
Windungen wenig, auf den äußeren nicht verdickt und lie-
gen auf einer Linie. Meist gabeln sich die Flankenrippen in
zwei Externrippen.

Die Lobenlinie ist nicht analysierbar.

Vergleich: Die Formen sind Dactylioceras pseudose-
micelatum Mauseuce, 1957 sehr ähnlich, welche Ho-
WARTH (1973: 255) mit Dactylioceras (Orthodactylites)
crosbeyi (Sımpson) vergleicht.

Verbreitung: Tennicostatum-Zone (simplex-Sub-
zone von Chile). Nach HowarTH (1973: 255) sind solche
Formen in England besonders für die tiefere tenuicosta-
tum-Zone (clevelandicum-Subzone) bezeichnend.

3.2.2 Nodicoeloceras cf. eikenbergi (HOFFMANN, 1968)
Taf. 3, Fig. 1; Abb. 16k
cf. 1968 Dactylioceras (? Orthodactylites) eikenbergi nov. spec.
— HOFFMANN: 8, Taf. 1, Fig. 2a-c.
cf. 1972 Nodicoeloceras eikenbergi (HOFFMANN, 1968) -
SCHMIDT-EFFING: 126, Taf. 14, Fig. 3a, b, Taf. 15,
Fig. 2a, b, Taf. 16, Fig. 1a, b, Taf. 19, Fig. 1.
cf. 1973 Dactylioceras (Orthodactylites) clevelandicum sp. nov.
— HOWARTHR: 257, Taf. 3, Fig. 1-3, Taf. 4, Fig. 1, 2,
Tafs5yEig, 3:
Material: Ein Fragment eines soweit erkennbar adul-
ten Exemplars (Abschnitte von drei Windungen) von
Quebrada Chanchoquin (B. St. M. 1978 II 78; Steinkern

mit verkieselter Schale).

Weitere Exemplare (Steinkerne) liegen von der Que-
brada El Penon (Abb. 3a, Schicht 4) (B. St. M. 1978 II
233-239) vor.

Maße: Ursprünglicher Durchmesser erwa 90 mm.

Beschreibung: Gehäuse scheibenförmig, im Bereich
der inneren Windungen wenig evolut, der letzten Win-
dung sehr evolut. Der Windungsquerschnitt ist breit oval.
Externkante nicht ausgebildet, Nabelkante abgerundet,
Externfläche breit-gerundet. Zur Mündung flachen die
Flanken ab und der Windungsquerschnitt wird rundlicher
(WB/WH etwa 1,2).

Die Rippen sind relativ fein, stehen dicht und spalten an
einem meist leicht verdickten Rippenspaltpunkt in sehr
spitzem Winkel in zwei Externrippen. Sie verlaufen pro-
radiat, teils auch proklin.

Eine Lobenlinie ist nicht zu beobachten.

Vergleich: Das beschriebene Fragment stimmt gut
mit den Beschreibungen von Horrmann (1968),
SCHMIDT-ErFinG (1972) und HowaRrTH (1973) überein. Wie
HOwARTH und SCHMIDT-ErrinG feststellen, ist diese Art
recht variabel. Als wichtiger Unterschied ist festzuhalten,
daß das chilenische Exemplar keinen solch ausgeprägten
Skulpturwechsel von den inneren zur äußeren Windungen

zeigt (ähnlich auch das Exemplar auf Taf. 3, Fig. la, ın:
HowAarTH 1973).

Bemerkungen: Howartk (1973: 257-258) be-
schreibt als neue Art ‚‚Dactylioceras clevelandicum“, das
nur aus Yorkshire bekannt sein soll. Ich halte diese Art je-
doch, da ich keinen wesentlichen Unterschied feststellen
kann, für ein Synonym von Nodicoeloceras eikenbergi.

Verbreitung: Tiefere tennicostatum-Zone (,,cleve-
landicum-Subzone“) von England, Norddeutschland,
Spanien und Chile (simplex-Subzone).

3.2.3 Nodicoeloceras cf. crassoides (Simpson, 1855)
Form A
Taf. 3, Fig. 24; Abb. 16 1, m

Synonymie: vgl. die umfangreiche Synonymieliste in
SCHMIDT-ErFinG (1972: 122).

Material: a) Quebrada Yerbas Buenas (Abb. 1, Pro-
fil 9, Abb. 6, Schicht 7), topographische Karte 1:100000,
Blatt Carrera Pinto: x = 439,4 km, y = 6979,3 km. Vier
Fragmente jeweils etwa eines halben Umgangs als Stein-
kerne, teils auch mit Schale (B. St. M. 1978 1179-82), zu-
sammen mit Hildaites cf. serpentiniformis (BUCKMAN),
Hildaites cf. serpentinus (REınEckE), Harpoceratoides cf.
alternatus (Sımpson) und Polyplectus sp.

b) Quebrada Calquis (Abb. 1, Profil 15), topographi-
sche Karte 1:100000, Blatt La Guardia: x = 402,7 km,
y = 6909,5 km. Ein ungünstig erhaltener Steinkern einer
äußeren Windung (B. St. M. 1978 II 83, ursprünglicher
Durchmesser mindestens 65 mm), zusammen mit Dacty-
lioceras (Orthodactilites) hoelderi n. sp.

Maße (in mm):

Nr. DM WH WB WB/WH

79 etwa 89 mm 26 2739 (1,06)
24 27 (1,13)
20,5 25 (1,22)

82 mind. 57 mm 13 16,5 (1,27)

81 mind. 30 mm 11 12 (1,09)

80 mind. 30 mm _ _ —

Beschreibung: Breit ovaler, weitgehend zugerunde-
ter, im adulten Stadium rundlicher Windungsquerschnitt,
bei leicht abgeflachten Flanken. Lediglich die Nabelkante
ist leicht angedeutet. Die konkave Windungszone ist sehr
gering (etwa '/, der Windungshöhe).

Die Rippen verlaufen rectoradiat über Flanken und Ex-
ternfläche, auf der Nabelfläche allerdings teilweise auch
retroklin. Neben dichotomer Rippengabelung treten auch
viele Einfach- und Schaltrippen auf. Auf den Steinkernen
erscheinen die Rippen breitrundlich, bei Schalenerhaltung

sind sie jedoch breit und hoch, entsprechend sind die In-
terkostalräume bei Schalenerhaltung breiter. Die Rippen
stehen mäßig dicht.

Vergleich: Das Material von Quebrada Yerbas Bue-
nas ist. sehr einheitlich. Das Exemplar von Quebrada Cal-
quis ist zu ungünstig erhalten, daß seine Zuordnung völlig
gesichert wäre.

Mit Nodicoeloceras crassoides im Sinne von SCHMIDT-
Erring (1972: 122) stimmen diese Formen recht gut über-
ein. Doch hat HowarTH (1978: 258) diese, abgesehen von
einigen englischen Formen, nicht in seine Synonymieliste
von Nodicoeloceras crassoides aufgenommen, obwohl er
auf der anderen Seite diese Art außerordentlich weit faßt.
So synonymiert er mit Nodicoeloceras crassoides auch so
wichtige Arten wie Nodicoeloceras annulatum, offen-
sichtlich auch Nodicoeloceras crosbeyi, das HOwarTH
(1973) mit diesem synonymiert hat, obwohl diese Formen
1978 nicht in der Synonymieliste erscheinen, und Nodi-
coeloceras pingne. Da es sich in allen Fällen um englische
Typen handelt, soll hier keine weitere Stellungnahme dazu
bezogen werden.

Verbreitung: Höheres Unter-Toarcium (hoelderi-
Zone) von Chile.

3.2.4 Nodicoeloceras cf. crassoides (Sımpson, 1855)
Form B
Taf. 3, Fig. 5; Abb. 16n

Material: Quebrada El Asiento (Abb. 2, Profil 6), to-
pographische Karte 1:100000, Blatt Potrerillos: x =
467,9 km, y = 7072,85 km. Ein Schale-tragender Stein-
kern (B. St. M. 1978 II 84) aus den rostbraun anwittern-
den Kalken (Abb. 3, Schicht 4).

Maße: DM = 65 mm; WH = 19,5 (0,3); WB = ca. 23
(0,35); NW = 31 (0,48); WB/WH = (1,18).

Kurzbeschreibung: Ähnlich Nodicoeloceras cf.
crassoides Form A, doch ist der Windungsquerschnitt
noch rundlicher ausgebildet, da auch keine Nabelkante
angedeutet ist. Ebenfalls in der Skulptur herrscht Über-
einstimmung, doch abweichend sind auf den Innenwin-
dungen in Abständen von 2 bis 3 Flankenrippen ausge-
prägte Knötchen entwickelt, ein Merkmal, das häufig bei
Nodicoeloceras crassoides beobachtet wird.

Verbreitung: höheres Unter-Toarcium (hoelderi-
Zone) von Chile.

3.2.5 Nodicoeloceras cf. crassoides (Sımpson, 1855)
Form C
Taf. 3, Fig. 6; Abb. 160

Material: a) Quebrada El Asiento (Abb. 2, Profil 4),
topographische Karte 1:100000, Blatt Potrerillos: x =
467,6 km, y = 7070,7 km. Ein Steinkern mit Schalen-

resten, besonders der Rippen (B. St. M. 1978 II 85), aus
den rostbraun anwitternden Kalken (Abb. 3, Schicht 4).

b) Rio Jorquera (Majada del Carrizo) (Abb. 9,
Schicht 7): 7 Steinkerne (B. St. M. 1978 11 222-228), zu-
sammen mit Dactylioceras (Orth.) directum, Polyplectus
sp., Harpoceras cf. falcıfer, Hildaites cf. levisoni (groß-
wüchsig).

Maße: Maximaler Durchmesser etwa 83 mm; DM =
75 mm; WH = 20,5 (0,27); WB = 22,5 (0,3: Wert viel-
leicht aus diagenetischen Gründen zu gering); NW = 35
(0,47); WB/WH = (1,1).

Beschreibung: Scheibenförmiges Gehäuse, wobei
die Windungszunahme (WH, WB) im Bereich der Innen-
windungen groß, auf dem letzten Umgang (wahrschein-
lich die Wohnkammer) aber gering ist. Der Windungs-
querschnitt ist breit oval, wobei die Flanken abgeflacht
sind. Eine Nabelkante ist angedeutet, eine Externkante

fehlt.

Die Skulptur wird durch sehr kräftige, dicht stehende
Vollrippen gebildet, die auf dem Steinkern nur eine relativ
schwache Rippenspur zurücklassen. Hohlrippen sind
nicht zu beobachten. Auf dem letzten Umgang dominie-
ren Einfachrippen gegenüber Spaltrippen. Auf den In-
nenwindungen scheinen Knötchen an den Rippenspalt-
punkten aufzutreten, doch ist durch die weitgehende
Überdeckung der folgenden Windungen keine sichere
Aussage möglich. Die Rippen verlaufen rectoriat über
Flanken und Externseite, auf der Nabelfläche aber retro-
klin, weshalb als Gesamteindruck die Rippen etwas ge-
schwungen erscheinen.

Vergleich: Das beschriebene Stück ist am besten mit
Nodicoeloceras annulatum vergleichbar (vgl. Synonymie-
liste und Beschreibung in SCHMIDT-EFFInG 1972: 124-126).
Doch stellt HowartH (1978: 256) den Lectotypus dieser
Art, der nur in der unklaren Abbildung von SowErBY
(1819: Taf. 222, Fig. 5) in der Literatur zugänglich ist, zu
Nodicoeloceras crassoides. Diese von HowArTH (1978)
vollzogene Synonymierung mag für die englischen For-
men gelten, nicht notwendigerweise für die nicht-engli-
schen (vgl. 5.52). Die Entscheidung, ob es sich hier um ein
echtes Nodicoeloceras crassoides handelt, was eine beson-
ders große Variabilität dieser Art voraussetzen würde,
oder eine noch nicht benannte Art, kann nur an einem um-
fangreicheren Material getroffen werden.

Verbreitung: Nach Howarrk (1973, 1978) tenuicos-
tatum- und falcifer-Zone. In Chile in der hoelderi-Zone
des höheren Unter-Toarciums. ö

Nodicoeloceras sp.

Aus dem Profil Quebrada Yerbas Buenas liegt ein
Fragment (B. St. M. 1978 II 86) vor, das wegen zu unvoll-
ständiger Erhaltung artlich nicht bestimmbar ist.

3.3 GENUS: PERONOCERAS HYATT, 1867

Typus-Art: Ammonites fibulatus SOwERBY, 1823

Diagnose: Gehäuse evolut, scheiben- bis napfförmig.
Windungsquerschnitt wenig bis stark abgerundet, trapez-
förmig oder rechteckig bis quadratisch. Windungsbreite
im allgemeinen größer als Windungshöhe. Skulptur kräf-
tig, charakteristisch das fibulate Berippungsmuster, kann
zu einfacher Flankenberippung reduziert sein. Rippen-
spaltpunkte mit Dornen oder Knoten versehen. Flanken-
rippen in 2 bis 3 Externrippen aufgespalten.

Bemerkungen: Wie Fischer (1966) und SCHMIDT-Er-
FING (1972, 1975) halte ich Porpoceras Buckman, 1911
(Typus-Art: Ammonites vortex Sımpson, 1855) für ein Sy-
nonym von Peronoceras. Auch Telodactylites Pınna &
Levı-Serti, 1971 (Typus-Art: Ammonites desplacei D’OR-
BIGNY, 1844) muß als Synonym von Peronoceras betrach-
tet werden. Die Abgrenzung einiger Arten gegenüber
Nodicoeloceras BuckMAn, 1926 ist schwierig, vor allem
dann, wenn die Wohnkammer nicht vorhanden ist. Die
typischen Arten von Nodicoeloceras besitzen ausgeprägte
Wachstumsallometrien (SCHMIDT-ErrinG 1972, $. 63). Die
Abgrenzung gegenüber Collına Bonareıuı, 1893 (Ty-
pus-Art: Collina gemma BoNARELLI, 1893) ist bei Arten,
die auf der Externfläche keine kielartige Erhöhung besit-
zen, ebenfalls schwierig. Diese Arten unterscheiden sich
dann von Peronoceras vor allem durch das sehr evolute,
flachscheibenförmige Gehäuse mit mehr oder minder
quadratischem Windungsquerschnitt.

Bei den stratigraphisch älteren Arten der Gattung Pero-
noceras tritt das fibulate Berippungsmuster vorwiegend in
bereits älteren Stadien auf und kann in jüngeren Stadien
wieder fehlen. Bei den stratigraphisch jüngeren Arten
fehlt zumeist das fibulate Berippungsmuster bei den älte-
ren Stadien und ist wie bei Collina (Pınna & Levı-Serti
1971, S. 112) deutlicher bei den jüngeren Stadien ausge-
prägt. Es besteht also die phylogenetische Tendenz wäh-
rend der Ontogenese, das fibulate Berippungsmuster auf
immer jüngere Stadien zu verlegen.

Nach Schmipr-ErrinG (1972, $. 176) sind die Ahnen
von Peronoceras wahrscheinlich bei Dactylioceras (Dac-
tylioceras) des Unter-Toarcium zu suchen (s. a. HOWARTH
1962 b, Gurx 1971). KoTTek (1966) leitet Peronoceras von
Nodicoeloceras ab. Pınna & Levi-Serti (1971, Fig. 16) un-
terscheiden zwischen einer phylogenetischen Entwick-
lung in der zentraleuropäischen und der mediterranen
Faunenprovinz, wobei Peronoceras von Dactylioceras
(Dactylioceras), Nodicoeloceras und Collina von Dacty-
lioceras (Orthodactylites) und Telodactylites von Meso-
dactylites abgeleitet werden. Zu Nodicoeloceras werden
von Pınna & Levi-Settı auch Arten (P. verticosum,
P. vorticellum, P. choffati) gerechnet, die bisher von den
meisten Autoren Peronoceras zugeordnet wurden.

Eine Darstellung der Verwandtschaftsverhältnisse eini-
ger Arten von Peronoceras wurde von FiscHEr (1966,

Tab. 3) gegeben. Sie stimmt nicht überein mit der phylo-
genetischen Entwicklung, die von Pınna & Levi-Serti
(1971) angenommen wird. So werden bei Fischer Perono-
ceras verticosum, P. vorticellum und P. vortex von P. fı-
bulatum über P. acanthopsis und P. desplacei abgeleitet.
Pınna & Levi-setti hingegen stellen P. verticosum und
P. vorticellum zur Gattung Nodicoeloceras und leiten
beide Arten von Nodicoeloceraten der falcifer-Zone ab.
Peronoceras vortex wird bei dieser Gattung belassen,
während P. acanthopsis (=P. renzi [Pınna & Le£vi-SET-
rı]) und P. desplacei zur Gattung Telodactylites gerechnet
werden.

Howarrtk (1973, S. 248) hingegen stellte fest, daß es alle
Übergänge zwischen Peronoceras vortex, P. verticosum
und P. vorticellum gibt und auch bei Dactylioceras (Or-
thodactylites) die Variationsbreite sehr groß ist. So lange
noch derartig unterschiedliche Meinungen zur Phylogenie
der Peronoceraten bestehen, erscheint es nicht ange-
bracht, diese in mehrere Gattungen aufzuspalten.

Das vorliegende Material reicht leider für variationssta-
tistische Untersuchungen nicht aus, sowohl was die An-
zahl der vorhandenen Exemplare als auch den Erhaltungs-
zustand anbelangt.

Aus diesen Gründen war ein eindeutiger Vergleich mit
europäischen Formen bei keiner Art möglich, was in den
cf.-Bestimmungen zum Ausdruck kommt. Neue Arten
wurden nur dann aufgestellt, wenn einerseits keine Über-
einstimmung zu bereits bekannten Formen bestand und
andrerseits das Material nach Anzahl der Exemplare und
Erhaltungszustand die Aufstellung einer neuen Art zu-

ließ.

3.3.1 Peronoceras cf. subarmatum (Young & Bırp, 1822)

Taf. 3, Fig. 7-10; Abb. 17d, f, 18a
cf. 1962 Peronoceras subarmatum (YOUNG and BIRD). — HO-
WARTH, S$. 117, Taf. 17, Fig. 5a, b (Neotypus).
cf. 1978 Peronoceras subarmatum (YOUNG & BIRD 1822). —
HOWARTH, S. 262, Taf. 4, Fig. 4, 5, 7.
Bemerkungen: HowarTH (1962) stellte für Perono-
ceras subarmatum einen Neotypus auf, der möglicher-
weise dem Holotypus entspricht.

Aus dem Mediterranbereich wurde in den letzten Jah-
ren mehrfach P. subarmatum beschrieben und abgebildet

(ZanzuccHi 1963, Pınna 1966, KortEk 1966, FiscHER
1966, GaLLitELLı WENDT 1969, Pınna & Levi-Serti 1971,
Drzı & Rıvorrı 1975). Der Erhaltungszustand der meisten
abgebildeten Exemplare erlaubt es nicht, diese eindeutig
P. subarmatum zuzuweisen.

Die von Zanzucchi (1963) und FiscHEr (1966) unter
P. subarmatum abgebildeten Exemplare werden von
Pınna & Levi-Serti (1971) Peronoceras vortex (SIMPSON)
zugeordnet. Sicherlich handelt es sich jedoch zumindest
bei den von Fischer (1966) abgebildeten Exemplaren um
eine mit P. subarmatum sehr nahe verwandte Form und
nicht um P. vortex.

Material: a) Quebrada EI Bolito (Abb. 5), topogr.
Karte 1:100 000, Blatt Laguna del Negro Francisco: x =
456,5 km, y= 6994,5 km. Ein Steinkernexemplar
(B. St. M. 1978 II 87) (Taf. 3, Fig. 7; Abb. 17d, 18a),
sowie ein weiteres Exemplar aus wahrscheinlich etwas
jüngeren Schichten (B. St. M. 1978 II 88). Zwei weitere
Exemplare gehören wahrscheinlich ebenfalls zu dieser Art
(B. St. M. 1978 II 89 u. 90). Zusammen mit Peronoceras
largaense n. sp., Harpoceras cf. chrysanthemum (Yo-
KOYAMA) und Mercaticeras sp.

b) Quebrada Larga (Abb. 7), topogr. Karte 1:100000,
Blatt Carrera Pinto: x = 432,7 km, y = 6978,7 km. Ein
Exemplar (Abb. 17f) (B. St. M. 1978 II 91), sowie wei-
tere Exemplare, die wahrscheinlich zu dieser Art gehören
(B. St. M. 1978 11 92, 93, 94).

c) Rio Jorquera (Majada del Carrizo) (Abb. 9), topogr.
Karte 1:100000, Blatt La Guardia: x = 437,4 km, y =
6931,7 km, 2 Steinkernexemplare (B. St. M. 1978 1195 u.
96) (Taf. 3, Fig. 8), 2 Windungsbruchstücke (B. St. M.
1978 II 97 u. 98) (Taf. 3, Fig. 9, 10) zusammen mit Pero-
noceras largaense und Harpoceras sp.

d) Quebrada El Asiento, topogr. Karte 1:100000, Blatt
Potrerillos, Profil4 (Abb. 2): x= 467,6km, y=
7070,7 km, 2 Steinkernexemplare (innere Windungen
schlecht erhalten) (B. St. M. 1978 II 99 u. 100), 1 Stein-
kernexemplar (1 cm ®, innere Windungen) B. St. M.
1978 II 101), 1 Windungsbruckstück (B. St. M. 1978 I
102). Zusammen mit Harpoceras cf. falcıfer. Profil 3
(Abb. 2): x = 467,5 km, y = 7070,45 km, 3 Exemplare
von unvollständigen, inneren Windungen (B. St. M. 1978
II 103 bis 105).

Maße:
d N H Q z
B. St. M. 1978 1187 1,25 cm 0,55
3,65 47 30 0,73 42
B. St. M. 1978 II 89 6,0 cm 47 30 0,84
B. St. M. 1978 11 88 3,1 46 30,5 0,7
B. St. M. 1978 11 91 4,7 47 30 0,78
B. St. M. 1978 II 95 6,0 cm 45 3155 0,9
4,3 44 32:9 0,8

Beschreibung: Die vorliegenden Exemplare können
nur mit Vorbehalt zu P. subarmatum gestellt werden, da
sie für einen genauen Vergleich nicht ausreichend erhalten
sind. Zumindest sind sie jedoch mit P. subarmatum nahe
verwandt.

Sämtliche Exemplare liegen als Steinkerne vor. Bei den
Innenwindungen der weitgenabelten Gehäuse ist der
Windungsquerschnitt breit trapezförmig und wird dann
allmählich breit rechteckig, wobei der Q-Wert größer
wird. Am Ende des Phragmokon wird die vorher deutli-
che Externkante abgerundet.

Fibulate Flankenrippen mit Knoten herrschen vor allem
auf dem Phragmokon vor, während auf der Wohnkammer
zunehmend diesen zwischengeschaltete einfache Flanken-
rippen häufiger werden, die zumeist gegabelt, selten un-
gegabelt sind und vorwiegend am Spaltpunkt keinen Kno-
ten besitzen. Selten vereinigen sich auch 3 Rippen zu ei-
nem Knoten. Von den Knoten gehen 2 bis 3 Spaltrippen
aus. Die äußere Lobenlinie wurde bei einem Exemplar ge-
zeichnet (Abb. 18a). Extern- und Laterallobus sind gleich
tief, der U, ist wesentlich kleiner.

Verbreitung: Peronoceras subarmatum kommt nach
HowarTtH (1978) in Europa in der fibulatum-Subzone
vor.

3.3.2 Peronoceras largaense n. sp.
Taf. 4, Fig. 14, Abb. 171

Holotypus (B. St. M. 1978 II 106): Schalenexemplar
mit ? Teil der Wohnkammer (Taf. 4, Fig. 1; Abb. 171).

47.

Derivatio nominis: Nach dem Vorkommen in der

Quebrada Larga.

Locus typicus: Quebrada Larga (Provinz Atacama)
(Abb. 1, Profil 11), topogr. Karte 1:100000, Blatt Car-
rera Pinto: x = 432,7 km, y = 6978,7 km.

Stratum typicum: Wechsellagerung von sandigen
Kalkbänken mit Kalkmergeln, die Ammoniten (P. cf.
subarmatum, P. largaense n. sp., Harpoceras sp., Merca-
ticeras sp.) enthalten.

Mittleres Toarcium, Zone des Hildoceras bifrons, Sub-
zone des Peronoceras largaense (= commune - bzw. sub-
levisoni-Subzone in Europa).

Diagnose: Gehäuse stark evolut, scheibenförmig,
Windungsquerschnitt annähernd quadratisch, fibulate
Flankenrippen mit langen Stacheln oder Knoten, von de-
nen 2 bis 3 nach vorn gebogene Externrippen ausgehen.
Einfache Schaltrippen selten.

Material: a) Am locus typicus wurde außer dem Ho-
lotypus ein weiteres, kleines Steinkern-Exemplar
(B. St. M. 1978 II 107) (Taf. 4, Fig. 2), sowie ein Stein-
kern-Windungsbruchstück gefunden (B. St. M. 1978 II
108) (Taf. 4, Fig. 4).

b) Quebrada EI Bolito (Abb. 5), topogr. Karte
1:100000, Blatt Laguna del Negro Francisco: x =
456,5 km, y = 6994,5 km.

3 Steinkernexemplare (B. St. M. 1978 II 109 bis 111)
(Taf. 4, Fig. 3), sowie Steinkern-Windungsbruchstücke
(B. St. M. 1978 II 112, 113). Zusammen mit P. cf. subar-
matum, Harpoceras cf. chrysanthemum, Mercaticeras sp.

Maße: d N H Q 7
Holotypus 4,9 cm 57 2335 0,9 50FR ca. 72ER
4,2 55 ca. 22 ca. 0,8 40FR
Paratypen
B. St. M. 1978 II 107 335 52,5 2653 0,97
B. St. M. 1978 II 109 355 ca. 50 28-29 0,85 51 FR

(Anfang letzter Umgang)

Beschreibung des Holotypus: Der Holotypus
liegt in Schalenerhaltung vor und wurde auf einer Seite aus
der kalkig-mergeligen Matrix herauspräpariert. Zumin-
dest ein Teil der letzten Windung dürfte bereits der
Wohnkammer angehören.

Das Gehäuse ist stark evolut. Die Windungen umfassen
sich nur wenig. Der Nabel ist wenig eingesenkt, da die
Windungsbreite im Verhältnis zur Windungshöhe wäh-
rend der Ontogenese allmählich abnimmt. Der Win-
dungsquerschnitt ist am Ende des letzten Umgangs fast
quadratisch (Q = 0,9), zu Beginn des letzten Umgangs
etwas breiter als hoch (Q = 0,8). Die Externseite ist wenig
gewölbt.

Bis zu einem Nabeldurchmesser von ca. 3 mm sind auf
Grund der ungenügenden Erhaltung die Rippen schlecht
zu erkennen, dann sind Einzelrippen zu erkennen, ab ei-

nem Nabeldurchmesser von ca. 4 mm treten fibulate Rip-
penpaare auf. Der externe Vereinigungspunkt ist zu einem
langen Dorn verlängert, der bis zur Mitte des nächsten
Umgangs reichen kann. Auf dem vorletzten Umgang tritt
das fibulate Berippungsmuster zurück, da sich jede zweite
Flankenrippe nur wenig an die dorntragende Rippe an-
lehnt oder als Schaltrippe ausgebildet ist. Bedingt, zumin-
dest verstärkt, wird dies wahrscheinlich durch die
Schalenerhaltung. Auf dem letzten Umgang treten wieder
häufiger fibulate Rippen auf, die auf der Externkante einen
kräftigen Knoten tragen (der ursprünglich sicherlich auch
hier vorhandene Dorn ist nicht erhalten).

Die fibulaten Flankenrippen spalten in 2 bis 3 Extern-
rippen auf. Den fibulaten Flankenrippen sind am Ende des
letzten Umgangs einige Einfachrippen zwischengeschal-
tet, die nicht in Gabelrippen aufspalten. Auf 50 Flanken-
rippen kommen im letzten Umgang ca. 72 Externrippen.

na]

e
ie:
2:
eW:

Abb. 17: Windungsquerschnitte, nat. Gr. a: Peronoceras cf. bolitoense n. sp.; Juntas del Toro; B. St. M.
1978 11154. b: Peronoceras bolitoense n. sp., Holotypus; Quebrada El Bolito; B. St. M. 1978 11146. c: Pe-
ronoceras cf. bolitoense n. sp.; Quebrada Yerbas Buenas; B. St. M. 1978 IL 153. d: Peronoceras cf. subar-
matum (YOUNG & BIRD, 1822); Quebrada El Bolito; B. St. M. 1978 Il 87. e: Peronoceras pacificum n. sp.;
Quebrada Yerbas Buenas; B. St. M. 1978 11123. f: Peronoceras cf. subarmatum (YOUNG & BIRD, 1822);
QuebradaLarga;B. St. M. 1978 IL 91. g: Peronoceras bolitoense n. sp.; QuebradaEl Bolito; B. St. M. 1978
II 147. h: Peronoceras sp. cf. P. cf. verticosum (BUCKMAN, 1914); Quebrada Yerbas Buenas; B. St. M.

1978 IL 136. i: Peronoceras largaense n. sp., Holotypus; Quebrada Larga; B. St. M. 1978 II 106. k: Collina
chilensis n. sp., Holotypus; Quebrada EI Bolito; B. St. M. 1978 II 176.

£
7
&

Die Flankenrippen stehen vorwiegend rectoradiat, sel-
ten leicht retroradıat. Spaltet ein fibulates Rippenpaar in
3 Externrippen auf, so ist der Verlauf der ersten Extern-
rippe gerade, die zweite Externrippe ist etwas und die
dritte kräftig nach vorn gebogen. Ein Zick-Zack-Muster
tritt selten auf, da die Externrippen, die von dem Knoten
der einen Seite ausgehen, sich auf der anderen Seite auch
wieder in einem Knoten vereinigen.

Beschreibung der Paratypen: Bei den Paratypen
handelt es sich um Steinkerne. Die Lobenlinie ist jedoch
an keinem Exemplar zu erkennen, da vorwiegend die
Wohnkammer erhalten ist.

Die Nabelweite und der Windungsquerschnitt entspre-
chen denen des Holotypus.

Fibulate Flankenrippen herrschen bei sämtlichen Para-
typen vor. Manchmal sind auch 3 Flankenrippen extern
zu einem Knoten vereinigt (nicht abgebildete Seite
B. St. M. 1978 II 107 [Taf. 4, Fig. 2]). Bei Exemplar
B. St. M. 1978 II 109 (Taf. 4, Fig. 3) ist nur die Wohn-
kammer in der Länge von einem Umgang erhalten. Die
letzte Hälfte der Wohnkammer ist zunehmend Richtung
Mündung verdrückt. Auf der ersten Hälfte herrschen fi-
bulate Flankenrippen vor, auf der zweiten Hälfte sind die-
sen zunehmend Gabel- und Einzelrippen zwischenge-
schaltet und die Flankenrippen nehmen einen retroradia-
ten Verlauf an. Die Knoten der fibulaten Rippen entsen-

den 2 bis 3 Externrippen. Teilweise tritt bei den Extern-
rippen ein Zick-Zack-Muster auf.

Vergleiche: Peronoceras subarmatum und P. cf. su-
barmatum besitzen einen breiteren Windungsquerschnitt.
Peronoceras fibulatum (Sow.) weist eine stark gewölbte
Externseite auf.

3.3.3 Peronoceras cf. desplacei (D’OrsıcnYy, 1844)
Taf. 4, Fig. 7, 10

cf. 1844 Ammonites Desplacei D’ORB. — D’ORBIGNY, $. 334,
Taf. 107, Fig. 144.

cf. 1971 Telodactylites desplacei (D’ORBIGNY, 1844). PINNA &
LEvıi-SETTI, S. 117, Taf. 10, Fig. 10-14, Taf. 11,
Fig. 9; Fig. 21/12.

cf. 1976 P. desplacei (D’ORB. 1844). - SCHLEGELMILCH, $. 79,
Taf. 40, Fig. 1.

Weitere Literatur bei PINNA & LEVI-SETTI (1971).
Material: Quebrada Yerbas Buenas (Abb. 6), topogr.

Karte 1:100000, Blatt Carrera Pinto:x = 439,45 km, y =

6979,53 km. 1 kleines, unvollständiges Exemplar

(B. St. M. 1978 II 114) (Taf. 4, Fig. 10), 1 halbes Exem-

plar (B. St. M. 1978 11115) (Taf. 4, Fig. 7) mitangeschlif-

fenem Querschnitt, dessen Flanken schlecht sichtbar sind.

Außenwindungsbruchstücke von Exemplaren mit einem

Durchmesser von ca. 6 cm können nur mit Vorbehalt zu

dieser Art gestellt werden. Zusammen mit Peronoceras cf.

choffati, P. sp. exgr. P. subarmatum und Harpoceras cf.

chrysanthemum.

Maße: D N H Q
B. St. M. 1978 11 115 4,2 cm 43 33 0,7
B. St. M. 1978 II 114 2,5 ‚43 30 0,69

Beschreibung: Die beiden vorliegenden Exemplare
sind nicht ausreichend erhalten, um eindeutig Peronoceras
desplacei zugeordnet werden zu können. Die Gehäuse
sind mäßig evolut, die Umgänge umfassen sich zu einem
Drittel. Der Nabel ist schüsselförmig eingesenkt. Der
rundlich querovale Windungsquerschnitt ändert sich nur
wenig während der Ontogenese. Die Externseite und die
Flanken sind stark gewölbt. Bei dem kleinsten Exemplar
trägt jede zweite rectoradiate Flankenrippe einen Knoten,
von dem 2 bis 3 Externrippen ausgehen. Die Rippen ohne
Knoten sind Einfach- oder Gabelrippen. Deutlich fibulate
Rippen kommen nicht vor.

Auch bei den größeren Exemplaren, die nur mit Vorbe-
halt zu P. cf. desplacei gestellt werden können, ist jede
zweite rectoradiate Flankenrippe mit einem Knoten ver-
sehen, von dem jedoch vorwiegend 3 Externrippen aus-
gehen. Die Schalrippen bleiben einfach oder sind bifurkat
aufgespalten. Fibulate Rippen sind etwas häufiger.

Vergleiche: Der Windungsquerschnitt ist etwas we-
niger breit als bei Peronoceras desplacei. Die Art der Be-
rippung stimmt weitgehend mit der dieser Art überein.

Verbreitung: Peronoceras desplacei ist nach FISCHER
(1966) in Europa aus der fibulatum- und braunianum-
Subzone bekannt.

3.3.4 Peronoceras cf. renzi (Pınna & Levı-Serti, 1971)

Taf. 4, Fig. 8; Abb. 18c, d, e
non 1912 Coeloceras Desplacei D’ORB. — RENZ, S. 61, Taf. 6,
Fig. 6
cf. 1971 Telodactylites renzi n. sp. - PINNA & LEVI-SETTI,
S. 117, Taf. 10, Fig. 1-5; Fig. 14B; Fig. 21/7.
Bemerkungen: Pınna & Levı-Serti (1971) benannten
die Art nach C. Renz, der eine ähnliche Art unter Coelo-
ceras desplacei D’Ors. abbildete. Das Original zu dem von
Renz (1912) abgebildeten Exemplar befindet sich im Na-
turhistorischen Museum in Basel. Einen Gipsabguß dieses
Originals erhielt ich freundlicherweise von Herrn
Dr. F. WIEDENMAYER. Die Maße sind:

Der wenig breitovale, rundliche Querschnitt gleicht
mehr dem von Peronoceras desplacei, stimmt jedoch auf
keinen Fall mit dem Querschnitt von Peronoceras renzi
(Q = 0,5 bis 0,65) bei Pınna & Levi-Serri überein. Nach
diesen Autoren unterscheidet sich Peronoceras renzi von
P. desplacei hauptsächlich dadurch, daß bei P. renzi die
fibulate Berippung ontogenetisch früher erscheint.

Material: a) Rio Jorquera (Majada del Carrizo)
(Abb. 9), topogr. Karte 1:100000, Blatt La Guardia: x =

437,35 km, y = 6931,75 km: 2 Windungsbruchstücke
(B. St. M. 1978 II 116 u. 117), zusammen mit nicht näher
bestimmbaren Windungsbruchstücken von Peronoceras
sp. und Harpoceras sp.

b) Quebrada La Chaucha (Abb. 1, Profil 6), topogr.
Karte 1:100000, Blatt Laguna del Negro Francisco: x =

468 km, y = 7011 km. Ein nicht horizontiert entnomme-
ner Steinkern (B. St. M. 1978 II 118) (Taf. 4, Fig. 8).

Maße:
d N H Q
B. St. M. 1978 II 118 3,5cm 48,5 28,5 0,61
116 0,57

Beschreibung: Der Erhaltungszustand der vorlie-
genden Exemplare reicht für eine eindeutige Zuordnung
nicht aus.

Die Gehäuse sind mäßig evolut. Die Umgänge umfas-
sen sich nur wenig. Der Nabel ist schüsselförmig einge-
senkt. Der Windungsquerschnitt ist breit rechteckig, die

Externkante nur wenig abgerundet. Die Externseite und
die Flanken sind wenig gewölbt.

Vor allem bei dem Exemplar von der Quebrada La
Chaucha sind - so weit erkennbar - fibulate Rippen vor-
handen, die an einem deutlichen Knoten in vorwiegend
3 Externrippen aufspalten. Den fibulaten Rippen können

innen
en

0 1

Abb. 18:

Lobenlinien a: Peronoceras cf. subarmatum (XOUNG & BIRD, 1822);

2cm

Quebrada EI Bolito;

B. St. M. 1978 1187. b: Peronoceras sp. ex gr. P. bolitoense n. sp.; Quebrada u B. St. M. 1978
11152. c: Peronoceras cf. renzi (PINNA & LEVI-SETTI, 1971); Rio Jorquera; B. St. M. 1978 II 116. d: Pero-

noceras cf. renzi (PINNA & LEVI-SETTI, 1971

); Rio Jorquera; B. St. M. 1978 II 116. e: Peronoceras cf.

renzi (PINNA & LEVI-SETTI, 1971); Rio Jorquera; B. St. M. 1978 II 117.

einfache Rippen zwischengeschaltet sein, die sich ohne
Knoten bifurkat teilen. Die Windungsbruchstücke von
der Majada del Carrizo zeigen die fibulate Berippung we-
niger deutlich (bedingt auch durch den Erhaltungszu-
stand).

Bei Exemplar B. St. M. 1978 II 116 ließ sich bei der
vorletzten Windung die innere und bis zur Externkante
die äußere Lobenlinie, sowie auf dem äußeren Umgang die
vollständige äußere Lobenlinie zeichnen (Abb. 1$c, d).
Bei Exemplar B. St. M. 1978 II 117 konnte die vollstän-
dige Lobenlinie gezeichnet werden (Abb. 18e). Lateral-
lobus und Externlobus sind nahezu gleich groß. Der Um-
bilikallobus U; ist bedeutend kleiner als der Laterallobus.
U, und U, sind dreispitzig. Die von PnnAa & Levi-Serti
(1971) abgebildete äußere Lobenlinie von Peronoceras
renzi ist sehr ähnlich.

Verbreitung: Peronoceras renzi kommt nach Pınna
& Levi-Setti in der bifrons-Zone vor.

3.3.5 Peronoceras cf. choffati (Renz, 1912)
Taf. 4, Fig. 5, 6
cf. 1912 Coeloceras Choffatı n. sp. - RENZ, S. 86, Taf. 6, Fig. 5

Bemerkungen: Durch Herrn Dr. F. WIEDENMAYER
erhielt ich einen Gipsabguß des Holotypus von Peronoce-

ras choffati, der sich im Naturhistorischen Museum in Ba-
sel befindet. Seine Maße sind:

d N H Q 7
3535 47 29 0,5 48
Can2al 45 33 0,47 38

Die von Pınna & Levi-Serrti (1971, S. 100, Taf. 4, Fig.
3-7, 10, 13) als Nodicoeloceras choffati bezeichneten und
abgebildeten Exemplare, sowie die in deren Synonymieli-
ste angeführten Exemplare, können nicht zu Peronoceras
choffati gestellt werden, da sie sämtlich eine weit geringere
Windungsbreite (bei Pnna & Levi-Sertı Q = 0,53 bis
0,73) besitzen. Das bei Pınna & Levi-Serti in der Syno-
nymieliste genannte Exemplar von Monsstier (1931,
Taf. 1, Fig. 28) wurde von Gurx (1972, S. 623) als Porpo-
ceras cf. crassicostatum Gurx bezeichnet und läßt sich
noch am besten mit P. choffati vergleichen. Peronoceras
crassicostatum ist allerdings etwas weniger weitnabelig
(weniger Umgänge) und besitzt in den Innenwindungen
keine fibulaten Rippen.

Material: Quebrada Yerbas Buenas (Abb. 6), topogr.
Karte 1:100000, Blatt Carrera Pinto:x = 439,45 km, y =
6979,3 km. Zwei unvollständige Exemplare (B. St. M.
1978 IL 119 u. 120), zusammen mit Peronoceras cf. despla-
cei, P. sp. exgr. P. subarmatum und Harpoceras cf.chry-
santhemum.

Maße:
d N H Q
B. St. M. 1978 II 119 SZ 45 29,5 0,51
120 ea. 0,55

Beschreibung: Beide Exemplare sind unvollständig
und können deshalb nur mit Vorbehalt P. choffati zuge-
ordnet werden. Bei Exemplar B. St. M. 1978 II 119
(Taf. 4, Fig. 5) ist nur die äußere Windung erhalten, die
den für P. choffati typischen Windungsquerschnitt zeigt.
Das zweite Exemplar B. St. M. 1978 II 120 ist mit ca. 125°
der Windungen (ohne die innersten) erhalten. Der Quer-
schnitt wurde poliert (Taf. 4, Fig. 6), die Flanken konn-
ten jedoch nicht gut präpariert werden. Der Wert von Q
liegt mit ca. 0,55 etwas höher als bei P. choffati. Soweit
erkennbar, zeigen beide Exemplare fibulate Berippung.
Die Flanken- und Externrippenzahl ist kleiner als bei
P. choffati. Die fibulaten Rippenpaare endigen in einem
deutlichen Knoten (bzw. Stachel bei dem angeschliffenen
Exemplar), und von diesem gehen 3 bis 4 Externrippen
aus. Den fibulaten Rippen können einfache oder gegabelte
Rippen (ohne Knoten) zwischengeschaltet sein. Bei
Exemplar B. St. M. 1978 II 119 muß es sich um einen Teil
der Wohnkammer handeln, da keine Lobenlinie erkenn-
bar ist. Das zweite Exemplar ist bis zu seinem Ende ge-
kammert.

Verbreitung: Aus der Faunenliste von Renz (1912)
ist schwer zu ermitteln, welcher Faunenzone der Holoty-

pus von P. choffati entstammt. MoUTERDE (1967) und
Gasıry et al. (1971) geben P. choffati aus der serpenti-
nus-Zone von Portugal an, die der falcifer-Zone ent-
spricht. Peronoceras crassicostatum kommt nach Gurx
(1972) im oberen Teil der bifrons-Subzone vor.

3.3.6 Peronoceras pacıficum n. sp.
Taf. 4, Fig. 9, 11-16, Taf. 5, Fig. 1, 2; Abb. 17e, 19a
1966 Peronoceras vorticellum (SımPsoN) 1855. — FISCHER, S. 41,
Taf. 2, Fig. 2, Taf. 6, Fig. 8.

Holotypus (B. St. M. 1978 II 125): Leicht verdrück-
ter Phragmokon (vorwiegend Schalenerhaltung) mit
°/a Windung Wohnkammer (Taf. 4, Fig. 13).

Derivatio nominis: Nach dem Vorkommen im Be-
reich des Pazifik.

Locus typicus: Quebrada Potrerillos (Abb. 1, Profil
10); topogr. Karte 1:100000, Blatt Carrera Pinto: x =
444,25 km, y = 6976,4 km.

Stratum typicum: Fossilschicht in gebankten Kal-
ken mit schiefrigen Mergellagen.

Fauna: Peronoceras pacificum, P. cf. verticosum, Har-
poceras sp., Maconiceras sp.

Der nächste Fossilhorizont im Liegenden feinschichtige
Kalke mit Pectinula cancellata. Im Hangenden weiterhin
gut gebankte Kalke mit schiefrigen Zwischenlagen. Ober-
ster Abschnitt der Serie mit wenige Meter mächtigen,
mehr knolligen Kalken und Phymatoceras.

Altersstellung: Mittleres Toarcium, Zone des Hıl-
doceras bifrons, Subzone des Peronoceras pacificum (=
tieferer Teil der bifrons- bzw. fibulatum-Subzone in Eu-
ropa).

Diagnose: Gehäuse mittelwüchsig, weitnabelig und
scheibenförmig. Windungsquerschnitt subquadratisch.
Flankenrippen dichtstehend, vorwiegend rectoradiat.
Phragmokon und erste Hälfte der Wohnkammer jede
zweite Flankenrippe mit Stachel (bzw. Knoten). Fibulate
Flankenrippen z. T. auf Wohnkammer vorhanden, am
Ende vorwiegend Einzelrippen. Knoten (bzw. Stachel)
Spaltpunkt für 2 bis 3 Externrippen, selten Zick-Zack-
Muster.

Material: a) Am Locus typicus wurden außer dem
Holotypus ein unvollständiges Exemplar (B. St. M. 1978

II 126) (Abb. 19a, Taf. 4, Fig. 16) (parallel zur Win-
dungsachse halbiert, äußerer Umgang Wohnkammer), ein
weiteres unvollständiges Exemplar (B. St. M. 1978 IL 127)
(Taf. 4, Fig. 12) (Außenskulptur der Wohnkammer nicht
erhalten) und Windungsbruchstücke gefunden.

b) Quebrada Yerbas Buenas (Abb. 6), topogr. Karte
1:100000, Blatt Carrera Pinto: x = 439,55 km, y =
6979,3 km. 3 Wohnkammerexemplare (B. St. M. 1978 II
121 bis 123) (Taf. 4, Fig. 9, 11, 15), z. T. mit Resten der
Schale, Phragmokon mit Kalzit ausgefüllt und unregel-
mäßig gespalten; ein kleines Exemplar (nur Externseite
freipräpariert) (B. St. M. 1978 II 124) (Taf. 4, Fig. 14),
Windungsbruchstücke. Zusammen mit Peronoceras cf.
verticosum, Maconiceras sp. und Polyplectus sp.

c) Quebrada El Bolito (Abb. 5), topogr. Karte
1:100000, Blatt Laguna del Negro Francisco: x =
458,4 km, y = 6995,5 km. 2 Wohnkammersteinkerne
(B. St. M. 1978 II 128 und 129) (Taf. 5, Fig. 1, 2), letzte
Windung des Phragmokons mit Kalzitresten, sonst flach-
gepreßt. Zusammen mit Harpoceras sp., Maconiceras sp.,
Polyplectus sp.

Maße:
d N H Q Z
B. St. M. 1978 II 121 3,85 cm 52 26
122 4,4 55 25 059
123 4,15 53 26,5 1,0
3,6 50 27,8 0,9
126 4,93 57 23,3 1,1
3,95 52,5 25,3 ca. 1,1
350 50,0 cau29 1,05
1 4,8 55,5 24 €4..0,9 59
129 2 53 26,5 0,92 60

Beschreibung: Die scheibenförmigen Gehäuse sind
stark evolut, und die Windungen umfassen sich nur we-
nig. Der Windungsquerschnitt ist wenig breiter als hoch
bis wenig höher als breit. Die Externseite ist etwas ge-
wölbt. Während der Ontogenie wird der Q-Wert größer.
Die innersten Windungen sind glatt. Als erstes erscheinen
am Außenrand der Flanken kleine Stacheln, ab einer Na-
belweite von ca. 1 mm allmählich Flankenrippen (Taf. 4,
Fig. 16, ce).

Die Flankenrippen stehen vorwiegend rectoradiat, am
Ende der Wohnkammer leicht retroradiat. Auf dem
Phragmokon (ab n 2,5 mm) und ersten Hälfte der Wohn-
kammer trägt jede zweite Flankenrippe einen Knoten
(Steinkern) oder langen Stachel (Schale). Fibulate Flan-
kenrippen können am Ende der ersten Hälfte der Wohn-
kammer auftreten. Auf der zweiten Hälfte der Wohn-
kammer werden Rippen ohne Knoten zunehmend häufi-
ger. Von den Knoten gehen zwei, selten drei Spaltrippen
aus, die auf der Externseite leicht nach vorn gebogen sind.
Ein Zick-Zack-Muster ist nur selten vorhanden. Die Rip-
pen ohne Knoten spalten zumeist nicht auf.

Die Lobenlinie konnte bei keinem der Exemplare ge- -
zeichnet werden.

Vergleiche: Peronoceras vorticellum (Simpson) ist
sehr ähnlich, besitzt jedoch einen etwas breiteren Win-
dungsquerschnitt, und die Windungshöhe ist im Verhält-
nis zum Durchmesser kleiner. Bei Peronoceras krumbecki
(Monssrier) beträgt das Verhältnis von Windungshöhe zu
Windungsbreite 1,5 bis 1,6 und ist somit größer als bei
P. pacificum.

Gute Übereinstimmung besteht zu dem von FiscHER
(1966) unter P. vorticellum abgebildeten Exemplar, das
einen ähnlichen Windungsquerschnitt (Taf. 2, Fig. 2) wie
die im chilenischen Lias gefundenen Exemplare besitzt.

Bemerkungen: Peronoceras pacificum gehört in den
Formenkreis von P. vorticellum. Nach Fischer (1966)
steht Peronoceras vorticellum am Anfang einer morpho-
logischen Reihe, die von dieser Artüber P. verticosum zu
P. vortex führt. Pınna & Levi-Serri (1971) stellen P. ver-
ticosum und P. vorticellum zur Gattung Nodicoeloceras
und halten die Unterschiede zwischen beiden Arten für

gering, während P. vortex unter der Gattung Peronoce-
ras aufgeführt wird. HowartH (1973) beobachtete in der
braunianus-Zone von Yorkshire eine kontinuierliche Va-
rıation zwischen P. vorticellum, P. verticosum und
P. vortex. Die Holotypen von P. vorticellum und
P. verticosum unterscheiden sich hauptsächlich durch die
verschiedene Gehäusegröße, was durch Dimorphismus
bedingt sein könnte.

Gurx (1973) hält die von ihm als Collina gr. gemma
und Porpoceras gr. verticosum bezeichneten Exemplare
für ein dimorphes Paar. SCHMIDT-ErrinG (1975) wies dar-
auf hin, daß zwischen beiden ‚‚Arten‘ keine morphologi-

ie
3

(m)
2
1

A
0

Abb. 19:

schen Unterschiede bestehen, abgesehen vom Größenun-
terschied. Beide ‚‚Arten‘“ müßten also zumindest der glei-
chen Gattung, wenn nicht auch der gleichen Art zugeord-
net werden. Die von Guzx (1972) als Collina gemma und
Guzx (1973) als C. gr. gemma bezeichneten Exemplare
stimmen nichtmit Collina gemma BonareıLı (Holotypus
neu abgebildet bei GarLimeLLı WEenpt 1969, Taf. 6,
Fig. 3a-c) überein. Es fehlt ihnen vor allem die für diese
Gattung und Art typische, kielartige Erhöhung auf der
Externseite. Die von Guzx (1972, 1973) abgebildeten Ex-
emplare sind zu Peronoceras zu stellen und gehören in die
Gruppe vorticellum-verticosum-vortex dieser Gattung.

Windungsquerschnitte a: Peronoceras pacificum n. sp.; Quebrada Potrerillos; B. St. M. 1978 II

126. b: Collina sp.; Quebrada Larga; B. St. M. 1978 II 209.

3.3.7 Peronoceras cf. verticosum (Buckman, 1914)
Taf.s5,WEig.3,65
cf. 1914 Porpoceras verticosum, nov. — BUCKMAN, Taf. 91 (Ho-
lotypus).
Bemerkungen siehe Peronoceras pacıficum.

Material: a) Quebrada Yerbas Buenas (Abb. 6), to-
pogr. Karte 1:100000, Blatt Carrera Pinto: x =
439,55 km, y = 6979,3 km. Ein Wohnkammersteinkern
(Phragmokon mit Kalzit ausgefüllt und unregelmäßig ge-
spalten) (B. St. M. 1978 II 130 [Taf. 5, Fig. 5]); ein Win-
dungsbruchstück. Faunenvergesellschaftung siehe bei
P. pacificum.

b) Quebrada Potrerillos (Abb. 1, Profil 10), topogr.
Karte 1:100000, Blatt Carrera Pinto:x = 444,25 km,y =

6976,4 km. Ein stark verdrücktes Exemplar mit Teilen der
Wohnkammer und teilweise erhaltenem Phragmokon
(B. St. M. 1978 II 131); Windungsbruchstücke. Faunen-
vergesellschaftung wie bei P. pacificum.

c) Quebrada Paipote bei Redonda (Abb. 4), topogr.
Karte 1:100000, Blatt Carrera Pinto: x = 436,3 km, y =
6996,55 km. Ein Wohnkammersteinkern (Phragmokon
nicht erhalten), der nur mit Vorbehalt zu dieser Art ge-
stellt werden kann (B. St. M. 1978 II 132) (Taf. 5, Fig. 3)
und auch zu Peronoceras cf. vortex gehören könnte. Zu-
sammen mit Peronoceras cf.bolitoense n. sp. und Collina
cf. chilensis n. sp. Aus annähernd gleichaltem Horizont
im Streichen des gleichen Profils Collina chilensis n. sp.,
Hildoceratidae gen. et sp. indet. (2 Arten).

d) Quebrada EI Asiento (Abb. 2, Profil 3), topogr.
Karte 1:100000, Blatt Potrerillos: x = 467,5 km, y =
7070,45 km. 2 Wohnkammersteinkerne (Phragmokon
nicht erhalten) (B. St.M. 1978 11 133 u. 134). Beide Exem-
plare wurden aus etwa 15 m mächtigen Knollenkalken ge-
sammelt, die auch Peronoceras cf. subarmatum sowie
Harpoceras sp. enthalten.

Die gleichen Schichten treten durch eine tektonisch be-
dingte Verdoppelung in dem gleichen Profil zweimal auf.
Vonx = 467,4 km und y = 7070,4 km stammt deshalb ein
weiterer Wohnkammersteinkern (B. St. M. 1978 II 135).

Maße:
d N H Q z
B. St. M. 1978 II 130 8,55 cm 56 4,5
7,0 54 2557 0,88 ca. 70
132 8,5 59 27. 0,8

Beschreibung: Die flachen Gehäuse sind weitnabelig.
Nur bei dem verdrückten Exemplar von der Quebrada
Potrerillos ist ein Teil des Phragmokons vorhanden, bei
allen übrigen Exemplaren ist nur die Wohnkammer erhal-
ten, die bei dem Exemplar aus der Quebrada Yerbas Bue-
nas eine Länge von zumindest 420° besitzt. Der abgerun-
det-rechteckige Windungsquerschnitt ist etwas breiter als
hoch. Die Externseite und die Flanken sind etwas ge-
wölbt. Auf dem Phragmokon (innerste Umgänge bei kei-
nem Exemplar erhalten) und zu Beginn der Wohnkammer
trägt jede zweite der rectoradiaten Flankenrippen einen
Knoten (Steinkern) oder Stachel (Schale). Fibulate Rippen
sind auf den ersten 90° der Wohnkammer zumeist selten,
treten dann regelmäßig auf und verschwinden wieder am
Ende der Wohnkammer. Zwischen den fibulaten Rippen-
paaren liegen 1 bis2 Flankenrippen ohne Knoten. Von den
Einfachrippen mit Knoten gehen zwei, von den fibulaten
Rippen zwei bis drei Spaltrippen aus. Besonders die je-
weils vorderste Spaltrippe ist auf der Externseite leicht
nach vorn gebogen. Die Flankenrippen ohne Knoten blei-
ben zumeist einfach, manchmal spalten sie auch in zwei

Externrippen auf. Zumindest nach 390° Wohnkammer (B.
St. M. 1978 II 130) treten vorwiegend Einfachrippen auf,
die nicht mehr aufspalten. Ein Zick-Zack-Muster ist auf
der Externseite nur selten vorhanden.

Die Lobenlinie konnte bei keinem der untersuchten Ex-
emplare beobachtet werden.

Vergleiche: Das Verhältnis von Nabelweite zu Ge-
häusedurchmesser (N) ist bei Peronoceras verticosum et-
was größer, bedingt durch die weniger schnell anwach-
sende Windungshöhe. Der Windungsquerschnitt ist sehr
ähnlich.

Verbreitung: Die Verbreitung in Europa ist die glei-
che wie bei Peronoceras vorticellum.

3.3.8 Peronoceras sp. ct. P. cf. verticosum BUCKMAN,
1914)
Taf. 5, Fig. 6; Abb. 17h
Material: Quebrada Yerbas Buenas (Abb. 6), topogr.

Karte 1:100000, Blatt Carrera Pinto: x = 439,55 km, y =
6979,3 km. Ein Exemplar (B. St. M. 1978 II 136).

Maße:

d N H Q Z
4,9 54 25,5 0,8 60
4,55 52:5 26,5 0,76 58

49 27. 0,76 51

Beschreibung: Von der gleichen Fundschicht, in der
Peronoceras cf. verticosum gefunden wurde, liegt ein Ex-
emplar vor, das sich von dieser Art durch die geringere
Größe, den etwas breiteren Windungsquerschnitt und das
Fehlen von fibulaten Rippen auch auf der Wohnkammer
unterscheidet.

Der mit Kalzit ausgefüllte Phragmokon endet wahr-
scheinlich etwas vor Beginn des letzten Umgangs, der als
Steinkern mit Schalenresten vorliegt und mit Sediment
ausgefüllt ist. Soweit erkennbar, ist ab einer Nabelweite

von ca. 4 mm auf dem Phragmokon und zu Beginn der
Wohnkammer jede zweite rectoradiate Flankenrippe mit
einem Stachel oder Knoten versehen. Auf der zweiten
Hälfte des letzten Umgangs liegen zwischen den leicht
rectoradiaten Flankenrippen zuerst 2, dann 3 und am
Ende 4 Rippen ohne Knoten. Die Rippen mit Knoten oder
jede zweite Flankenrippe spaltet in 2, selten 3 Externrip-
pen auf, die vordere leicht nach vorn gebogen. Auf der
zweiten Hälfte des letzten Umgangs bleiben zunehmend
2, am Ende auch 3 aufeinander folgende Flankenrippen

einfach.

3.3.9 Peronoceras cf. vortex (Sımrson, 1855)
Tat.'5, Eig.4, 7,8; Taf.'6, Fig. 1

cf. 1911 Porpoceras vortex, SIMPSON sp. — BUCKMAN, Taf. 29 A
(Holotypus) 29B.

cf. 1930 Deroceras subarmatum Y. et B. - RIGAL, S. 7, Taf. 2,
Fig. 4.

cf. 1976 Peronoceras vortex (SIMPSON 1855). — SCHLEGELMILCH,
S. 79, Taf. 40, Fig. 2 (Holotypus).

Bemerkungen siehe bei Peronoceras pacıfıcum.

Material: a) Quebrada Cortaderita (Abb. 1, Profil 8),
topogr. Karte 1:100000, Blatt Carrera Pinto: x
435,05 km, y = 6988,2 km. Ein Steinkernexemplar (B. St.
M. 1978 11 137) (Taf. 5, Fig. 7) mit Schalenresten auf dem
teilweise angebrochenen und mit Kalzit ausgefüllten
Phragmokon; ein Steinkernexemplar (B. St. M. 1978 II
138) (Taf. 5, Fig. 8) mit zwei unvollständig erhaltenen
äußeren Windungen. Zusammen mit Peronoceras cf. bo-
litoense n. sp., Collina chilensis n. sp., Harpoceras cf.
subexaratum, Phymatoceras ex gr. P. erbaense, Hildoce-
ratidae gen. et sp. indet.

b) Quebrada Llareta (Abb. 1, Profil 13), topogr. Karte
1:100000, Blatt La Guardia: x 438,6 km, y
6957,5 km. Ein senkrecht zur Aufrollungsachse ver-
drückter Steinkern (B. St. M.1978 II 139) (® ca. 8 cm) mit
etwas mehr als ein Umgang langer Wohnkammer, ein
Phragmokonsteinkern (B. St. M. 1978 II 140) (Taf. 5,
Fig. 4) von 2,5 cm Durchmesser und weitere, unvollstän-
dige, verdrückte Exemplare (B. St. M. 1978 II 141 und

142) können nur mit Vorbehalt zu dieser Art gestellt wer-
den. Zusammen mitMaconiceras sp., Polyplectus sp.,
Phymatoceras sp.

c) Quebrada Paipotito (Abb. 1, Profil 4), topogr. Karte
1:100000, Blatt Inca de Oro: x = 441,2 km, y
7013,65 km. Ein Wohnkammerexemplar mit etwas mehr
als 1'/, Umgängen, seitlich vermutlich stark komprimiert,
aber nur mit Vorbehalt zu dieser Art zu stellen (B. St. M.
1978 II 143) (Taf. 6, Fig. 1).

d) Quebrada El Hueso/Quebrada Cienaga (Abb. 2,
Profil 1), topogr. Karte 1:100000, Blatt Salar de Maricun-
ga: x = 463,9 km, y = 7065,6 km. Ein Steinkernexemplar
(B. St. M. 1978 II 144) (ca. 7,8 cm ©) kann nur mit Vorbe-
halt zu dieser Art gestellt werden. Die inneren Umgänge
sind nicht erhalten. Fibulate Rippen treten besonders am
Ende des letzten Umgangs auf. Der Windungsquerschnitt
ist weniger breit als bei P. cf. vortex.

e) Rio Jorquera (Vegas de Chanar) (Abb. 1, Profil 14a),
topogr. Karte 1:100000, Blatt La Guardia: x = 435,1 km,
y = 6931,1 km. Ein Steinkernexemplar (B. St. M. 1978 II
145) (8,4 cm ®), dessen äußerer Umgang nicht gekam-
mert ist. Die inneren Umgänge sind nicht erhalten. Fibu-
late Rippen treten am Ende des letzten Umgangs auf. Das
Exemplar kann nur mit Vorbehalt zu dieser Art gestellt
werden, da der Windungsquerschnitt weniger breit ist.
Die Flankenrippenzahl gleicht jedoch weitgehend der von
P. cf. vortex.

Maße:

d N H Q Z
B. St. M. 1978 II 137 1573 55 23 0,72 c2:,59
B. St. M. 1978 II 138 14525 58 20,5 0,76

9575 575 22,0 0,72
B. St. M. 1978 II 140 2,5 48 28 0,78 33
B. St. M. 1978 II 143 12,0 60 21
B. St. M. 1978 II 144 7,8 32 25 0,82 65
B. St. M. 1978 II 145 8,4 52,5 25 0,89

Beschreibung: Das flache Gehäuse ist weitgenabelt.
Der Windungsquerschnitt ist breiter alshoch. Die Extern-
seite und die Flanken sind gewölbt. Das kleine Exemplar
von der Quebrada Llareta (B. St. M. 1978 II 140) besitzt
erst ab einem Nabeldurchmesser von ca. 1 mm Flanken-
rippen, vorher sind kleine Stacheln zu beobachten, die
sich am Außenrand der Flanken befinden. Ab einem Na-
beldurchmesser von ca. 2,5 mm ist nur noch jede zweite
Rippe mit einem Stachel versehen. Bei dem kleineren Ex-
emplar aus der Quebrada Cortaderita trägt - soweit sicht-
bar — jede zweite der recto- bis leicht retroradiaten Flan-
kenrippen einen Knoten, von dem 2, selten 3 Externrip-
pen ausgehen, die gerade (selten leicht nach vorn gebogen)
die Externseite überqueren. Die Rippen zwischen den
Knotenrippen spalten zumeist nicht auf. Bei dem größe-
ren Exemplar aus der Quebrada Cortaderita und dem Ex-
emplar aus der Quebrada Paipotito sind besonders auf
dem letzten Umgang zahlreiche fibulate Rippen vorhan-
den. Bei dem kleineren Exemplar aus der Quebrada Cor-

taderita ist der letzte Umgang mit Sediment ausgefüllt,
und es ist keine Kammerung mehr zu erkennen. Wahr-
scheinlich handelt es sich um den ersten Umgang der
Wohnkammer. Bei dem größeren Exemplar endet die
Kammerung zu Beginn des erhaltenen, vorletzten Um-
gangs. Die Wohnkammer würde demnach bei diesem Ex-
emplar eine Länge von mehr als 1'/; Windungen besitzen.

Die Lobenlinie konnte bei keinem Exemplar beobachtet
werden.

Vergleiche: Peronoceras vortex ist noch etwas weit-
nabeliger und das Verhältnis von Windungshöhe zu Win-
dungsbreite etwas kleiner. Die Flanken der in Chile ge-
fundenen Exemplare sind stärker gewölbt. Auch bei P.
vortex erscheinen die fibulaten Rippen sehr spät.

Verbreitung: Die Verbreitung von P. vortex in Eu-
ropa ist die gleiche wie von P. vorticellum und P. vertico-
sum.

3.3.10 Peronoceras bolitoense n. sp.
Taf. 6, Fig. 2, 4-6; Abb. 17b, g, 18b, 20, 21

Holotypus (B. St. M. 1978 II 146): Teils als Stein-
kern, teils als Schalenexemplar erhalten, letzter Umgang
Wohnkammer, diese am Ende etwas seitlich verdrückt
(Taf. 6, Fig. 5; Abb. 17b).

Derivatio nominis: Nach dem Vorkommen in der

Quebrada El Boliıto.

Locustypicus: Quebrada El Bolito (Prov. Atacama)
(Abb. 5); topogr. Karte 1:100000, Blatt Laguna del Ne-
gro Francisco: x = 456,5 km, y = 6994,5 km.

Stratum typicum: Etwa I m mächtige, in sich 10 bis
20 cm gebankte Knollenkalke mit großwüchsigen Pero-
noceraten (zumeist nur Wohnkammer erhalten, Phrag-
mokon hohl), zwischen den Bänken weichere Lagen mit
verdrückten Peronoceraten. An der Basis der Knollen-
kalke eine knollige, kalkig-mergelige Schicht (rötlich) mit
zum Teil sehr gut erhaltenen Ammoniten (vorwiegend
Peronoceras und Collina).

Fauna: Peronoceras bolitoense n. sp., Collina chilen-
sis n. sp., Harpoceras sp., Maconiceras sp., Phymatoce-
ras sp., Hildoceratidae gen. et sp. indet. (glatte Art).

Im Liegenden der Knollenkalke Mergel mit Peronoce-
ras cf. vorticellum, Harpoceras sp., Maconiceras sp., Po-
Iyplectus sp. Im Hangenden 10 bis 20 cm gebankte Kalke
mit Phymatoceras cf. erbaense (Haurr), Hildoceratidae
gen. et sp. indet. (2 Arten mit retroklinen Rippen).

Altersstellung: Mittleres Toarcium, Zone des Hil-
doceras bifrons, Subzone der Collina chilensis, Horizont
mit Peronoceras bolitoense.

Die Fauna mit P. bolitoense n. sp. ist gleichaltrig mit
dem oberen Teil der Subzone des Hildoceras bifrons oder
tieferen Teil der Subzone des Hildoceras semipolitum
(Zone des Hildoceras bifrons) (Gasırty etal. 1971) in Eu-
ropa.

Diagnose: Gehäuse großwüchsig, weitnabelig und
scheibenförmig. Windungsquerschnitt rundlich bis sub-
quadratisch, dicht berippt, besonders auf der Wohnkam-
mer. Rippenzahl pro Umgang während der Ontogenie
stark zunehmend. Auf dem Phragmokon jede zweite
Flankenrippe mit Stachel versehen. Fibulate Rippen nur
auf der Wohnkammer, ihnen 2 bis 4 Einzelrippen ohne
Knoten zwischengeschaltet. Am Ende der Wohnkammer
ungespaltene Einzelrippen vorherrschend.

Material: a) Amlocus typicus wurden außer dem Ho-
lotypus 3 weitere Exemplare sowie ein Windungsbruch-
stück gefunden. Exemplar B. St. M. 1978 II 147 (Taf. 6,
Fig. 4; Abb. 178) ist nur halb erhalten und wurde zur Er-
mittlung des Windungsquerschnittes angeschliffen. Ex-
emplar B. St. M. 1978 II 148 (® 11 cm) ist seitlich kom-
primiert, und die inneren Umgänge sind nur als Abdruck
erhalten. Bei Exemplar B. St. M. 1978 II 149 sind nur 2
Umgänge des Phragmokons und diese unvollständig er-
halten. Das Windungsbruchstück (ca. '/; Windung) (B. St.
M. 1978 II 150) besteht aus zwei äußeren, ungekammerten
Windungen.

b) Rio Manflas (Department Copiapö, Prov. Atacama),
Profil zwischen dem Rio Manflas und dem Portezuelo El
Padre (70°0,9' Länge, 28°11,8’ Breite) (Abb. 1, Profil 16):
Ein kleines Exemplar (© 3 cm) mit gut erhaltenen Innen-
windungen (B. St. M. 1978 II 151) (Taf. 6, Fig. 6), zu-
sammen mit Windungsbruchstücken von Peronoceras
sp., Collina cf. chilensis n. sp., Polyplectus sp., Hildoce-
ratidae gen. et sp. indet. (glatte Art).

c) Quebrada Cortaderita (Abb. 1, Profil 8), topogr.
Karte 1:100000, Blatt Carrera Pinto: x = 435,05 km, y =
6988,2 km. Ein unvollständig erhaltener Steinkern mit
Resten der Wohnkammer B. St. M. 1978 II 152 (Taf. 6,
Fig. 2; Abb. 18b) kann nur mit Vorbehalt zu der neuen
Art gestellt werden.

Zusammen mit Peronoceras cf. vortex, Collina cf. chi-
lensis n. sp., Harpoceras cf. subexaratum, Phymatoceras
ex gr. P. erbaense, Hildoceratidae gen. et sp. indet.

Maße:
d N H Q Z
Holotypus B. St. M. 1978 II 146 8,6 cm 58 E= _ 109
7,7 55 2355 ca0595 93
6,0 52,5 25 0,9 63
5,5 51,5 26,5 0,9 57
Paratypus B. St. M. 1978 II 147 8,9 cm 58 23,5 0,95
Z51 55 24,5
5,6 50,5 DIN. 0,86
4,2 48 28,5 1,0
Paratypus 148 ca. 6,5 54 27
Paratypus 151 3,0 48 29,5 0,8-0,85 40
2,65 47,5 31,0 ca. 0,9 38
2,3 46 30,5 0,83 37
ca. 1,65 43 31,5 0,71 35
Paratypus 152 ca. 5,6 53,5 25,0 0,78-0,75
ca. 3,2 47,0 31 0,73 37
ca. 2,35 45,0 2.132 0,73 33

12)

Nabelweite in % vom

5 10

Gehäuse © incm

Abb. 20: Änderung der relativen Nabelweite im Verlauf der Ontogenie bei Peronoceras bolitoense n. sp.
und Peronoceras cf. bolitoense n. sp. Peronoceras bolitoense n. sp.: X B. St. M. 1978 11152, @B. St. M.
1978 II151, MB. St. M. 1978 11149, + B. St. M. 1978 II 146, 4 B. St. M. 1978 II 147. Peronoceras cf. bo-
litoense n. sp.: « B. St. M. 1978 II 154, 4 B. St. M. 1978 II 153, O B. St. M. 1978 II 155.

Beschreibung des Holotypus: Die innersten

Windungen sind nicht erhalten. Die abgebildete Seite des
Phragmokons (Taf. 6, Fig. 5) liegt in Schalenerhaltung
vor und ist mit Kalzit ausgefüllt. Die mit einem Umgang
vorhandene Wohnkammer ist ein Steinkern mit Schalen-
resten. Besonders die letzten 110° der Wohnkammer sind
seitlich etwas verdrückt. Das Gehäuse ist weitnabelig und
scheibenförmig, der Nabel wenig eingesenkt. Der Win-
dungsquerschnitt ist rundlich, am Ende der erhaltenen
Wohnkammer subquadratisch.
Das Gehäuse, besonders die Wohnkammer, ist dicht be-
rippt. Die Anzahl der rectoradiaten Flankenrippen pro
Umgang nimmt während der Ontogenese stark zu
(Abb. 21). Auf dem Phragmokon (soweit sichtbar) ist jede
zweite Flankenrippe mit einem Stachel versehen, der sich
an den folgenden Umgang anlehnt. Die Stachellänge kann
bis '/; der Flankenhöhe betragen. Auf der ersten Hälfte
der Wohnkammer sind die Rippen schlecht zu erkennen,
auf der zweiten Hälfte sind fibulate Rippenpaare mit Kno-
ten vorhanden. Kurz vor Erreichen der Naht sind die
sonst rectoradiaten Flankenrippen nach vorn gebogen.
Zwischen den fibulaten Rippen stehen 2 bis 4 Einzelrip-
pen. Die fibulaten Rippenpaare spalten in 2 bis 3 Extern-
rippen auf. Die Einzelrippen bleiben einfach, soweit er-
kennbar. Der Verlauf der Externrippen ist gerade.

Die Lobenlinie konnte nicht ermittelt werden.

Beschreibung der Paratypen: Die relative Na-
belweite (N) wird während der Ontogenese allmählich

größer (Abb. 20) und die relative Windungshöhe (H) all-
mählich kleiner.

Der Windungsquerschnitt ist bei den ersten Windungen
des Phragmokons etwas breiter als hoch, wird dann rund-
lich und ist auf der zweiten Hälfte der Wohnkammer sub-
quadratisch, da hier die Flanken weniger stark gewölbt
sind. Die Externseite ist jedoch weiterhin stark gewölbt

(Abb. 17b, g).

Auf dem Phragmokon sind Vollrippen vorhanden.
Zumindest am Ende der Wohnkammer liegen Hohlrippen
vor. Die ersten Umgänge sind glatt. Bei einer Nabelweite
von 1,5 mm erscheinen dicht unterhalb der Naht kleine,
spitze Knoten, die erst ab einer Nabelweite von 2 mm mit
retroradiaten Flankenrippen verbunden sind. Jede der
Flankenrippen trägt zunächst einen Stachel. Allmählich
wird jedoch jeder zweite Stachel kleiner, und ab einer Na-
belweite von 5,5 mm ist nur noch jede zweite, nunmehr
rectoradiate Flankenrippe mit einem kräftigen Stachel ver-
sehen. Am Ende des vorletzten Umgangs des Phragmo-
kons sind bei Exemplar B. St. M. 1978 II 149 die Stacheln
(Schalenerhaltung) wieder kleiner (Länge ca. 2 mm). Auf
Steinkernexemplaren können die entsprechenden Knoten,
besonders am Ende des Phragmokons und zu Beginn der
Wohnkammer, schwach entwickelt sein. Bei Exemplar B.
St.M. 1978 II 148 treten einzelne fibulate Rippen etwa 90°
nach Beginn der Wohnkammer auf, und die fibulate Be-
rippung reicht bis kurz vor das Ende des 1. Umgangs der
Wohnkammer. Zwischen den fibulaten Rippen liegt zu-

5 10

Gehäuse 9% in cm

Abb. 21: Änderungder Flankenrippenzahl im Verlauf der Ontogenie bei Peronoceras bolitoense n. sp.: +
B. St. M. 1978 II 146 (Holotypus), @ B. St. M. 1978 II 151.

erst eine Flankenrippe ohne Knoten, dann sind es 2, 3 und
am Ende bis zu 4 Einfachrippen. Zumindest ab Ende des
1. Umgangs der Wohnkammer sind keine Knoten mehr
ausgebildet und Gabelrippen treten gegenüber Einzelrip-
pen zunehmend zurück. Bei Exemplar B. St. M. 1978 II
147 (Taf. 6, Fig. 4) kommen auf 25 Flankenrippen 28 Ex-
ternrippen (1. Hälfte des zu 120° erhaltenen äußeren Um-
gangs). Die Flankenrippen nehmen dann eine rectoradiate
bis leicht retroradiate Richtung ein. In Höhe des Spalt-
punktes können sie etwas retroklin werden. Auf der Ex-
ternseite verlaufen die Rippen auf dem größten Teil des
Phragmokons und der Wohnkammer vorwiegend gerade.
Bei Exemplar B. St. M. 1978 II 151 (3 cm ®) (Taf. 6,
Fig. 6) gehen von einem Knoten oder Stachel 2 bis 3 Ex-
ternrippen aus, wobei die vorderste Externrippe nach
vorn gebogen sein kann. Die zwischen den Stachelrippen
gelegenen Rippen bleiben einfach oder sie sind bifurkat
gespalten. Ein ausgeprägtes Zick-Zack-Muster besteht
nicht.

Exemplar B. St. M. 1978 II 152 (Taf. 6, Fig. 2) unter-
scheidet sich von den Exemplaren der Quebrada El Bolito
durch eine etwas größere Windungsbreite, die zwischen
der von Peronoceras bolitoense n. sp. und der von P. cf.
vortex liegt.

Bei diesem Exemplar konnte die äußere Lobenlinie ge-
zeichnet werden (Abb. 18b). Der Laterallobus ist etwas
kürzer als der Externlobus. Der Umbilikallobus U; ist
dreispitzig.

Vergleiche: Peronoceras bolitoense n. sp. unter-
scheidet sich von P. vortex und P. verticosum vor allem
durch die dichtere Berippung auf der Wohnkammer. Die
Windungsbreite ist bei ?. vortex größer und die Gehäuse-

größe bei P. verticosum kleiner. Die Windungshöhe
nimmt bei ?. bolitoense n. sp. schneller zu als bei den ge-
nannten Arten. Catacoeloceras (? = Peronoceras) tuber-
culatum Kortik (nach Pınna & Levi-Serti 1971 = Nodi-
coeloceras (? = Peronoceras) angelonü (RAMACCIONI) ist
ebenfalls ähnlich. Diese Art ist jedoch ebenfalls klein-
wüchsiger, besitzt einen breiteren Windungsquerschnitt
und eine geringere Rippenzahl pro Umgang.

3.3.11 Peronoceras cf. bolitoense n. sp.
Taf. 6, Fig. 3, Taf. 7, Fig. 3, 4; Abb. 17a, c

Material: a) Quebrada Yerbas Buenas (Abb. 6), to-
pogr. Karte 1:100000, Blatt Carrera Pinto: x = 439,4 km,
y = 6979,35 km. Phragmokon (teils Steinkern, teils Scha-
lenexemplar) mit Beginn und verdrücktem Ende des
l. Umgangs der Wohnkammer B. St. M. 1978 II 153
(Taf. 7, Fig. 3; Abb. 17c). Zusammen mit Collina chilen-
sis n. sp., Peronoceras sp. indet., Maconiceras sp., Hildo-
ceratidae gen. et sp. indet. (glatte Art).

b) Juntas del Toro (Department Copiapö, Provinz Ata-
cama), Profil auf der rechten Talseite, kurz unterhalb der
Vereinigung von Rio Manflas und Rio del Toro (Abb. 10)
(69°58,3’ Länge, 28°24,5’ Breite). Ein Phragmokon mit
Resten der Wohnkammer (B. St. M. 1978 II 154) (Taf. 7,
Fig. 4; Abb. 17a), ein zur Hälfte erhaltener Phragmokon
(B. St. M. 1978 II 155) (Taf. 6, Fig. 3), sowie Windungs-
bruchstücke. Zusammen mit Collina chilensis n. sp.,
Harpoceras cf. subexaratum, Phymatoceras sp., Hildo-
ceratidae gen. etsp. indet. (glatte Art und weitnabelige Art
mit retroklinen Rippen).

c) Rio Manflas (Department Copiapö, Provinz Ataca-
ma), Profil 2,5 km südlich Los Graneros, zwischen dem

Fluß und dem Cerro Salto del Toro (Abb. 10) (69°58,5’
Länge, 28°19,7’ Breite). Ein weniger als zur Hälfte erhal-
tenes Exemplar (@ 14 cm) mit verdrückten Innenwindun-
gen (B. St. M. 1978 11 156). Gleicher lithostratigraphischer
Horizont wie Profil Juntas del Toro.

d) Rio Pulido (Department Copiapö, Provinz Ataca-
ma), Profil südlich Iglesia Colorada auf der linken Talseite
(Abb. 10) (69°53,2’ Länge, 28°9,8’ Breite). Mehrere Win-
dungsbruchstücke (B. St. M. 1978 II 157 bis 159), die
wahrscheinlich zu dieser Art gehören. Zusammen mit

Collina chilensis n. sp., Harpoceras cf. subexaratum,
Hildoceratidae gen. et sp. indet. (glatte Art).

e) Rio Jorquera (Vegas de Chanar) (Abb. 1, Profil 14a),
topogr. Karte 1:100000, Blatt La Guardia: x= 435,1 km,
y = 6931,1 km. 1 Windungsbruchstück (B. St. M. 1978 II
160), das wahrscheinlich zu dieser Art gehört. Zusammen
mit Peronoceras cf. P. cf. vortex, Collina chilensis, Har-
poceras cf. subexaratum und Hildoceratidae gen. et sp.
indet. (glatte Art).

Maße:
d N H Q Z
B. St. M. 1978 II 153 7,2 cm 48 2% 0,85 68
585 45 31 0,88 53
39 43 32 ca. 0,8

154 8,2cm 52 24,4 0,87 ca. 70
6,4 48 29,0 0392 ca. 61
4,7 45 32,0 0,88 ca. 58

3,35 41,5 33,0 0,92

B. St. M. 1978 II 155 6,35 cm 48 28 0,86

4,75 42,5 31,5 0,88

3,4 ca. 40 car35 ca. 0,85

Beschreibung: Die Gehäuse sind mäßig weitnabelig.
Der Nabel ist wenig eingesenkt. Der rundliche bis sub-
quadratische Windungsquerschnitt ist wenig breiter als
hoch. Der Q-Wert verändert sich während der Ontoge-
nese nur wenig. Das Exemplar von der Quebrada Yerbas
Buenas zeigt bei einem Teil der Innenwindungen
(Schalenerhaltung) kräftig ausgebildete Flankenrippen-
Stachel, wobei jede zweite, manchmal jede dritte Flanken-
rippe einen Stachel trägt. Soweit erkennbar spalten die rec-
to- bis leicht retrocostaten Flankenrippen mit Knoten
(bzw. Stacheln) in vorwiegend 2 Externrippen auf. Die
Flankenrippen ohne Knoten bleiben zumeist einfach. Die
Externrippen überqueren die Externseite gerade. Fibulate
Rippenpaare sind bei diesem Exemplar nicht zu erkennen.
Es fehlt allerdings der größte Teil der Wohnkammer, und
die Rippen sind nur auf dem kurzen, erhaltenen Anfangs-
teil der Wohnkammer gut zu beobachten. Am Ende des
1. Umgangs der Wohnkammer stehen die Flankenrippen
sehr dicht.

Die beiden Exemplare von Juntas del Toro sind etwas
weniger engnabelig als das Exemplar von der Quebrada
Yerbas Buenas. Der Windungsquerschnitt ist ähnlich und
etwas weniger breit. Bei dem größeren Exemplar ist ein
Teil der Wohnkammer erhalten. Die Rippen sind nur bei
dem kleineren Exemplar gut zu erkennen (Taf. 6, Fig. 3).
Vorwiegend jede zweite Flankenrippe trägt einen Stachel
und spaltet in 2, manchmal 3 Externrippen auf. Die Schalt-
rippen bleiben einfach, oder sie sind ebenfalls als Gabel-
rippen ausgebildet. Auf dem erhaltenen Teil des letzten
Umgangs stehen die Flankenrippen dicht und biegen von
der abgerundeten Nabelkante nach vorn zur Naht hin um.

Das Exemplar (B. St. M. 1978 II 156) vom Profil südlich
Los Graneros muß einen Durchmesser von mehr als

14 cm besessen haben. Der Windungsquerschnitt ist
rundlich (Wohnkammer Q = 0,85 bis 0,9). Auf dem letz-
ten Umgang (Wohnkammer) stehen die etwas retroradia-
ten Flankenrippen ebenfalls dichter als auf der vorherge-
henden Windung. Einfachrippen sind häufiger als Gabel-
rippen (auf 30 Flankenrippen kommen 37 Externrippen).
Fibulate Rippenpaare treten nicht auf.

Vergleiche: Peronoceras cf. bolitoense unterscheidet
sich von P. bolitoense n. sp. durch die kleinere relative
Nabelweite (Abb. 20), das größere Gehäuse und die ge-
ringere Zahl von Flankenrippen bei einem Gehäuse-
durchmesser von 6 bis 8 cm.

Die Exemplare vom Rio Manflas und Rio Pulido besit-
zen auch Ähnlichkeit mit Peronoceras moerickei n. sp.,
das jedoch auf der Wohnkammer fibulate Rippen besitzt
und bei dem der Rippenabstand auf der Wohnkammer
größer ist.

Verbreitung: Die Exemplare vom Rio Manflas und
Rio Pulido kommen in etwas jüngeren Schichten als Pero-
noceras bolıtoense vor.

3.3.12 Peronoceras moerickei n. sp.
Taf. 7, Fig. 1, 2
1894 Deroceras aff. Davoei Sow.-MOÖRICKE, S. 11, Taf. 2,
Fig. 6.-

Holotypus (B. St. M. 1978 II 161): Steinkern der
Wohnkammer (500° lang) und Reste der letzten Windung
des Phragmokons (Taf. 7, Fig. 1).

Derivationominis: Nach W. Möricke, der als er-

ster ein dem Holotypus ähnliches Exemplar aus Chile ab-
bildete.

Locustypicus: Quebrada El Asiento (Provinz Ata-
cama) (Abb. 2, Profil 4), topogr. Karte 1:100000, Blatt
Potrerillos: x = 467,55 km, y = 7070,7 km.

Stratum typicum: Dichte, graue, knollige Kalke mit
wenig Fossilschutt und Gastropoden (vorwiegend klein-
wüchsig).

Etwa 10 m im Liegenden Harpoceras sp. und Perono-
ceras sp. in lithologisch ähnlichen Kalken, z. T. mitmehr
Fossilschutt und häufiger Ammoniten.

Etwa 10 m im Hangenden Grenze der knolligen bis
mehr oder minder gut gebankten Kalke (mit Catacoeloce-
ras sp., Collina sp.) gegen einen ca. 4 m mächtigen, in
sich gebankten, groben Fossilschuttkalk mit Brachiopo-
den und Pelecypoden, sowie Pleydellia cf. fluitans im lie-
genden und Bredyia spp. im hangenden Teil. Der Fossil-
schuttkalk greift mit Täschchen und Grabgängen in die
liegenden Knollenkalke.

Altersstellung: Mittleres Toarcium, Zone des Hil-
doceras bifrons, Subzone der Collina chilensis, Horizont
mit Peronoceras moerickei. Die Fundschicht mit Perono-
ceras moerickei n. sp. ist gleichaltrig mit dem oberen Teil
der Subzone des Hildoceras semipolitum (Zone des Hıl-
doceras bifrons) in Europa.

Diagnose: Sehr großwüchsige, weitnabelige Art mit
rundlichem Windungsquerschnitt. Mäßig dicht berippt,

Rippenabstand sich während der Ontogenese wenig ver-
ändernd. Fibulate Flankenrippen nur auf der Wohnkam-
mer. Rippen gerade die Externseite überquerend. Am
Ende der Wohnkammer ungegabelte Einzelrippen vor-
herrschend.

Material: a) Am locus typicus wurde nur der Holoty-
pus gefunden.

b) Salar de Pedernales, NW-Seite (Abb. 1, Profil 1),
topogr. Karte 1:100000, Blatt Potrerillos: x =
475,05 km, y = 7199,8 km und x = 475,75 km, y =
7100,75 km (zwei Fundpunkte aus der gleichen Schicht im
Streichen). Windungsbruchstücke (Phragmokon und
Wohnkammer) (B. St. M. 1978 II 162-168). Zusammen
mit Harpoceras cf. subexaratum, Maconiceras sp., Hil-
doceratidae gen. et sp. indet. (Innenwindungen berippt,
äußere glatt).

c) Das von MörıckE (1894) abgebildete Exemplar
(Taf. 2, Fig. 6) ist nicht mehr vorhanden. Es wurde bei La
Guardia gefunden (topogr. Karte 1:100000, Blatt La Gu-
ardıa: x = 445,3 km, y = 6935,5 km).

d) Quebrada Yerbas Buenas (Abb. 6), topogr. Karte
1:100000, Blatt Carrera Pinto: x = 439,4 km, y =
6979,3 km. Ein nicht im Anstehenden gefundenes Win-
dungsbruchstück der Wohnkammer (B. St. M. 1978 II
169) (Taf. 7, Fig. 2).

Maße:
d N H Q z
Holotypus B. St. M. 1978 II 161 16,0 cm 62
14,0 60 22 0,95 107
MÖRICKE (1894, Taf. 2, Fig. 6) 13,3 cm 58

BeschreibungdesHolotypus: Vom Phragmokon
sind nur Reste der letzten Windung erhalten. Die Wohn-
kammer besitzt eine Länge von 500° und ist am Ende seit-
lich verdrückt. Die Rippen sind nur auf der abgebildeten
Seite gut zuerkennen. Der Windungsquerschnitt ist rund-
lich (Q = 0,9 bis 0,95) und besonders die Externseite stark
gewölbt. Die Flanken sind auf dem Phragmokon ebenfalls
stark gewölbt und flachen auf der Wohnkammer allmäh-
lich ab. Die Flankenrippen stehen auf dem Phragmokon
rectoradiat, besonders auf der 2. Hälfte der Wohnkam-
mer können sie auch eine retrocostate Richtung einneh-
men. Auf dem letzten Umgang sind zahlreiche fibulate
Rippen zu erkennen, zwischen denen auf der 2. Hälfte des
letzten Umgangs 2 bis 3 Einzelrippen stehen. Von den fi-
bulaten Knoten gehen 2 bis 3 Externrippen aus. Die Ein-
zelrippen spalten bifurkat auf oder bleiben einfach. Die
Rippen überqueren die Externseite gerade.

Beschreibung der Paratypen: Das von MörıckE
(1894) als Deroceras aff. davoei bezeichnete Exemplar ist
auf keinen Fall mit Prodactylioceras davoei näher ver-
wandt, sondern muß zur Gattung Peronoceras gerechnet
werden. Am meisten Ähnlichkeit besitzt das von MORICKE
abgebildete Exemplar mit Peronoceras moerickei n. sp.

Nach Mörıcke besaßen die von diesem Autor beschriebe-
nen Exemplare (2 Stück) ebenfalls einen rundlichen Win-
dungsquerschnitt, etwas breiter als hoch. Fibulate Flan-
kenrippen sind bei dem abgebildeten Exemplar wie beim
Holotypus auf der Wohnkammer vorhanden. Die zwi-
schen den fibulaten Rippen liegenden Einzelrippen schei-
nen jedoch zahlreicher zu sein und somit auch der Ab-
stand der Knoten größer. Die Flankenberippung insge-
samt ist dichter. Am Ende der (erhaltenen) Wohnkammer
herrschen Einzelrippen vor, und die Flankenrippen stehen
immer stärker retroradiat.

Vom Salar de Pedernales liegen Windungsbruchstücke
des Phragmokons und der Wohnkammer vor, die sehr
große Ähnlichkeit mit dem Holotypus aufweisen. Bis zu
einer Windungshöhe von ca. 10 mm ist der Windungs-
querschnitt sehr viel breiter als hoch (Q = 0,65 bis 0,7),
wird dann zunehmend rundlicher und der Q-Wert beträgt
am ? Ende des Phragmokons bei einer Windungshöhe von
2,1 cm 0,9. Auf der Wohnkammer liegt der Q-Wert bei
0,95 (Wh 2,8 bis 2,9 cm). Die Flanken und die Externseite
sind auf dem Phragmokon stark gewölbt, auf der Wohn-
kammer flachen die Flanken ab. Bei den Innenwindungen
des Phragmokons trägt jede zweite rectoradiate Flanken-

rippe einen Stachel (Schale) oder Knoten (Steinkern), von
dem 2 bis 3 Externrippen ausgehen, die leicht nach vorn
gebogen sind. Die Schaltrippen bleiben einfach oder sind
bifurkat aufgespalten. Auf der letzten Windung des
Phragmokons sind die Knoten auf dem Steinkern stark
abgeschwächt. Auf eine bifurkate Rippe folgt zumeist eine
Einfachrippe, die gerade die Externseite überquert. Zwei
Wohnkammerbruchstücke zeichnen sich durch fibulate
Rippenpaare aus. Zwischen den beknoteten, fibulaten
Rippen liegen 1 bis 3 Einfachrippen oder unbeknotete
Spaltrippen. Ein drittes Wohnkammerbruchstück weist
eine dichtere Berippung als der Holotypus auf, die fibula-
ten Rippen stehen in großem Abstand, Einfach- und
Spaltrippen herrschen vor. Die Berippung gleicht mehr
der des von Möricke abgebildeten Exemplars.

Das 8cm lange Wohnkammer-Windungsbruchstück
(leicht seitlich verdrückter Steinkern) von der Quebrada
Yerbas Buenas (Taf. 7, Fig. 2) weist ebenfalls eine dich-
tere Berippung auf. Zwischen den fibulaten Rippen liegen
2 bis 4 einfache oder bifurkat aufgespaltene Schaltrippen.
Von den fibulaten Rippen gehen vorwiegend 3, manchmal
auch nur 2 Externrippen aus. Auf 35 Flankenrippen
kommen 47 Externrippen. Auch dieses Exemplar stimmt

gut mit dem von Mörıcke abgebildeten Exemplar überein.

Die Lobenlinie konnte bei keinem der Exemplare ge-
zeichnet werden.

Vergleiche: Peronoceras moerickei n. sp. unterschei-
det sich von sämtlichen bisher bekannten Arten durch die
Großwüchsigkeit. Die Art der Berippung gleicht der von
Peronoceras bolitoense n. sp., das jedoch feinrippiger ist
(vor allem auf der Wohnkammer). Peronoceras cf. vortex
besitzt einen breiteren Windungsquerschnitt. Auf den
Vergleich mit Peronoceras cf. bolitoense n. sp. wurde bei
der Beschreibung dieser Art hingewiesen.

3.3.13 Peronoceras cf. planiventer (Guzx, 1972)
Tat.18,, Eig.Hl
cf. 1972 Porpoceras planiventer sp. n.- GUEX, S. 633, Taf. 8,
Fig. 10, 14; Taf. 12, Fig. 7.

Material: Quebrada Larga (Abb. 7); topogr. Karte
1:100000, Blatt Carrera Pinto: x = 432,75 km, y =
6978,7 km. 1 Exemplar (B. St. M. 1978 II 170) zusammen
mit Peronoceras cf. crassicostatum, Collına sp., Polyplec-
tus sp., Osperlioceras sp., Phymatoceras ex gr. P. erba-
ense, Hildoceratidae gen. et sp. indet. (3 Arten).

Maße:
d N H Q Z
2,8cm 48 29,5 0,6 27.
2,4 48 ca. 30 0,6 23
0,56 (Beginn letzter Umgang)

Beschreibung: Es handelt sich um einen gekammer-
ten Steinkern mit Schalenresten (besonders bei den inne-
ren Umgängen). Das Gehäuse ist mäßig evolut, der Nabel
tief. Der Windungsquerschnitt ist breiter als hoch. Die
Flanken und die Externseite sind wenig gewölbt, und es ist
eine deutliche Externkante ausgebildet. Die Flankenrip-
pen stehen nicht sehr dicht. In den Innenwindungen ist
jede der recto- bis leicht proradiaten Flankenrippen mit
einem Knoten (Steinkern) oder Stachel (Schale) versehen.
Auf der letzten Windung können den Flankenrippen auch
Einzelrippen ohne Knoten zwischengeschaltet sein. Deut-
lich fibulate Rippen fehlen. Die Rippen mit Knoten spal-
ten in 3, selten 2 Externrippen auf. Die Einfachrippen sind
selten bifurkat gespalten.

Vergleich: Peronoceras planiventer besitzt große
Ähnlichkeit, ist jedoch etwas weitnabeliger. Bei dieser Art
ist außerdem nur jede zweite Flankenrippe mit einem
Knoten versehen. Bei dem von Gurx auf Taf. 8, Fig. 10
abgebildeten Exemplar scheinen jedoch bei den Innen-
windungen auch sämtliche Flankenrippen bedornt zu
sein. Peronoceras planiventer besitzt zusätzlich eine deut-

lich fibulate Berippung. Im Gegensatz zu sämtlichen an-
deren chilenischen Arten der Gattung Peronoceras (außer
P. cf. crassicostatum) sind bis zu einem Durchmesser von
2,5 cm sämtliche Flankenrippen mit einem Knoten bzw.
Stachel versehen.

Altersstellung: Peronoceras planiventer wurde von
Gusx aus dem oberen Teil der Subzone des Hildoceras bi-
frons beschrieben.

3.3.14 Peronoceras cf. crassicostatum (Gurx, 1972)
Taf. 8, Fig. 2; Abb. 22
cf. 1972 Porpoceras crassicostatum sp. n.- GUEX, S. 633, Taf. 8,
Eig.11,.17;, Tat. 12,,Eı8,9.

Material: Quebrada Larga (Abb. 7), topogr. Karte
1:100000, Blatt Carrera Pinto: x 432,75 km, y
6978,7 km. 5 unvollständig erhaltene Exemplare (B. St.
M. 1978 II 171-175) zusammen mit Peronoceras cf. pla-
niventer (Guzx), Collina sp., Polyplectus sp., Osperlio-
ceras sp., Phymatoceras ex gr. P. erbaense, Hildocerati-
dae gen. et sp. indet. (3 Arten).

Maße:
d N H Q
B. St. M. 1978 11 171 3,7cm 40 38 0,6
172 2,6cm 44 33 0,5

Beschreibung: Sämtliche Exemplare sind gekam-
mert. Das Gehäuse ist engnabelig und der Nabel tief ein-
gesenkt. Der rechteckige Windungsquerschnitt ist bis
doppelt so breit wie hoch. Die Flanken und die Extern-
seite sind wenig gewölbt. Es ist eine deutliche Externkante
ausgebildet. Die recto- bis leicht proradiaten Flankenrip-
pen enden in einem Stachel oder Knoten. Fibulate Flan-
kenrippen sind selten, treten jedoch bei einem Exemplar
bereits bei einer Windungshöhe von 6 mm auf. Von den
Knoten gehen 2 oder 3 Externrippen aus, die etwas nach
vorn gebogen sind.

Vergleiche: Peronoceras crassicostatum ist etwas
weitnabeliger und fibulate Flankenrippen treten regelmä-
Riger auf. Auch Nodicoeloceras fontis Gurx ist ähnlich.
Bei dieser Art trägt jedoch nur jede zweite Flankenrippe

Abb. 22: Windungsquerschnitt von Peronoceras
B. St. M. 1978 II 172.

3.4 GENUS: COLLINA BONARELLI, 1893

Typus-Art: Collina gemma Bonareıuı, 1893

Diagnose: Gehäuse flach-scheibenförmig und stark
evolut, Umgänge locker aufeinander liegend, Windungs-
querschnitt zumindest in den Außenwindungen subqua-
dratisch bis höher als breit. Skulptur kräftig, Flankenrip-
pen regelmäßig mit Dornen oder Knoten versehen. Fibu-
late Rippenpaare und kielartige Erhöhung — wenn über-
haupt vorhanden - vor allem auf der Wohnkammer aus-
gebildet. Die Externrippen queren die kielartige Erhö-
hung.

Laterallobus (nach GaıtrreLLı WEnDT 1969) bifid und
genauso tief wie der Externlobus. Internlobus ebenfalls

bifid, 3 Umbilikalloben, U, tiefer als I und U,;.

einen Knoten und fibulate Rippen fehlen. Das zusammen
mit P. cf. crassicostatum gefundene P. cf. planiventer
besitzt eine sehr ähnliche Berippung, ist jedoch weitnabe-
liger, und der Windungsquerschnitt ist weniger breit. Pe-
ronoceras choffati ist bereits in den Innenwindungen re-
gelmäßig mit fibulaten Rippen versehen. Transicoeloceras
viallii Pınna ist noch engnabeliger.

Altersstellung: Peronoceras crassicostatum wurde
von Guzx aus dem oberen Teil der Subzone des Hildoce-
ras bifrons beschrieben, Nodicoeloceras fontis vom glei-
chen Autor aus der Zone der Haugıa varabilıs.

Peronoceras cf. planiventer und P. cf. crassicostatum
sind die beiden jüngsten Vertreter der Gattung Peronoce-
ras, die im chilenischen Lias gefunden wurden.

cf. crassicostatum (GUEX, 1972); Quebrada Larga;

Bemerkungen: Collina unterscheidet sich von Pero-
noceras durch das stark evolute Gehäuse, den überwie-
gend weniger breiten Windungsquerschnitt und die kiel-
artige Erhöhung auf der Externseite. Nach Pınna &
Levi-Serri (1971) kann die kielartige Erhöhung auf der Ex-
ternseite auch fehlen, was dann eine Unterscheidung von
Peronoceras erschwert.

Arkops (1972) unterscheidet nach dem Dimorphismus
zwei Untergattungen. Die microconchen Gehäuse wer-
den zur Untergattung Collina und die macroconchen Ge-
häuse zur Untergattung Collinites Arrors, 1972 (Ty-
pus-Art: Collinameneghinit BONARELLI, 1899) gerechnet.
Nach Arkors unterscheidet sich Collinites von Collina
vor allem durch das Fehlen einer kielartigen Erhöhung auf
der Externseite. Auch sollen fibulate Rippen nicht vor-

handen sein, die jedoch sowohl bei der Typus-Art (Pınna
1969, Taf. 4, Fig. 7), als auch bei Collina kampemorpha
Korrek bei Pınna & Levi-Serri (1971, Taf. 9, Fig. 14) auf
der Wohnkammer zu erkennen sind.

Nach Carroman (1969) und anderen Autoren ist es
ratsam, dimorphe Arten zumindest der gleichen Gattung
oder Untergattung zuzuweisen.

Pınna & Levi-Serti (1971) stellen in die Synonymie von
Collina gemma 8 weitere Arten.

3.4.1 Collina chilensis n. sp.
Taf. 8, Fig. 3, 4, 6-12; Abb. 17b, 23, 24
Holotypus (B. St. M. 1978 II 176): Phragmokon
(z. T. in Kalzit erhalten), letzter Umgang Wohnkammer
(Steinkern), (Taf. 8, Fig. 4;
Abb. 17k).

Derivatio nominis: Nach dem Vorkommen in Chi-
le.

seitlich komprimiert

Locus typicus undStratum typicum wie bei Pe-
ronoceras bolitoense HiLLEBRANDT, n. sp. (S. 56).

:
E

Diagnose: Gehäuse flach-scheibenförmig und sehr
weitnabelig, Windungsquerschnitt bei den Innenwindun-
gen etwas breiter als hoch, bei der Wohnkammer subqua-
dratisch bis etwas höher als breit. Flankenrippenzahl nied-
rig, jede zweite Flankenrippe mit einem Dorn oder Kno-
ten versehen. Fibulate Rippen auf dem letzten Viertel des
ersten Wohnkammer-Umgangs. Flankenrippen mit Kno-
ten bifurkat in Externrippen aufspaltend, Schaltrippen
überwiegend einfach. Externseite häufig mit Zick-
Zack-Muster.

Material: a) Am locus typicus (Quebrada EI Bolito)
wurden außer dem Holotypus 7 weitere, unvollständig
erhaltene Exemplare gefunden (B. St. M. 1978 II 177 bis
183) (Taf. 8, Fig. 8-10).

b) Quebrada Cortaderita (Abb. 1, Profil 8); topogr.
Karte 1:100000, Blatt Carrera Pinto:x = 435,05 km, y =
6988,2 km. 4 Windungsbruchstücke (B. St. M. 1978 I
184-187), die nur mit Vorbehalt zu dieser Art gestellt
werden können. Zusammen mit Peronoceras cf. vortex,
P. cf. bolitoense n. sp., Harpoceras cf. subexaratum,

n
&

Abb. 23: Windungsquerschnitte von Collina chilensis n. sp. a: Rio Pulido; B. St. M. 1978 II 190. b:

Quebrada El Bolito; B. St. M. 1978 II 178.

Phymatoceras ex gr. P. erbaense, Hildoceratidae gen. et
sp. indet.

c) Quebrada Paipote bei Redonda (Abb. 4); topogr.
Karte 1:100000, Blatt Carrera Pinto: x = 436,3 km, y =
6996,55 km und x = 436,0 km, y = 6996,3 km. Aus an-
nähernd gleichalten Horizonten im Streichen 2 unvoll-
ständig und mäßig erhaltene Exemplare (B. St. M. 1978 II
188 u. 189), die nur mit Vorbehalt zu Collina chilensıs n.
sp. gestellt werden können. Aus dem gleichen Horizont
Peronoceras sp. cf. P. cf. verticosum, P. cf. bolitoense n.
sp., Hildoceratidae gen. et sp. indet. (2 Arten).

d) Rio Pulido (Department Copiapö, Prov. Atacama),
Profil südlich Iglesia Colorada auf der linken Talseite
(Abb. 10) (69°53,2’ Länge, 28°9,8’ Breite). Zwei unvoll-
ständig erhaltene Exemplare (B. St. M. 1978 II 190 u. 191)
(Taf. 8, Fig. 6, 7), 7 Fragmente bzw. Windungsbruch-
stücke (B. St. M. 1978 II 192 bis 198) (Taf. 8, Fig. 3). Zu-
sammen mit Peronoceras cf. bolitoense n. sp., Harpoce-
ras cf. subexaratum, Hildoceratidae gen. et sp. indet.
(glatte Art).

e) Juntas del Toro (Department Copiapö, Prov. Ataca-
ma), Profil auf der rechten Talseite, kurz unterhalb der
Vereinigung von Rio Manflas und Rio del Toro (Abb. 10)
(69°58,3’ Länge, 28°24,5’ Breite). Ein Windungsbruch-
stück (Steinkern) (B. St. M. 1978 II 199) der Wohnkam-
mer zusammen mit Peronoceras cf. bolitoense n. sp.,

Harpoceras cf. subexaratum, Phymatoceras sp., Hildo-
ceratidae gen. et sp. indet. (2 Arten).

f) Quebrada Yerbas Buenas (Abb. 6); topogr. Karte
1:100000, Blatt Carrera Pinto: x = 439,4 km, y =
6979,35 km. Ein kleines Exemplar (B. St. M. 1978 II 200)
mit schlecht erhaltenem Phragmokon und °/, Umgang der
Wohnkammer (Taf. 8, Fig. 12). Zusammen mit Perono-
ceras cf. bolitoense n. sp., Peronoceras sp. indet., Maco-
niceras sp., Hildoceratidae gen. et sp. indet. (glatte Art).

g) Profil südlich Quebrada El Corral (östliche Seiten-
quebrada der Quebrada La Totora) (Abb. 1, Profil 20);
topogr. Karte 1:50000, Blatt Conay: x = 381,3 km, y =
6818,9 km. Ein Wohnkammerexemplar (Phragmokon
nicht erhalten) (B. St. M. 1978 II 201) (Taf. 8, Fig. 11),
Windungsbruchstücke (B. St. M. 1978 II 202 bis 205). Zu-
sammen mit Catacoeloceras (?) sp., Harpoceras cf.
subexaratum, Hildoceratidae gen. et sp. indet. (2 Arten
mit retroklinen Rippen).

h) Rio Jorquera (Vegas de Chanar) (Abb. 1, Profil 14a),
topogr. Karte 1:100000, Blatt LaGuardia:x = 435,1 km,
y = 6931,1 km. Ein unvollständiges Exemplar (2 äußere
Windungen zu ?/; erhalten) (B. St. M. 1978 II 206), sowie 2
Windungsbruchstücke (B. St. M. 1978 II 207 u. 208) zu-
sammen mit Peronoceras cf. P. cf. vortex, P. cf. bolito-
ense, Harpoceras cf. subexaratum, Hildoceratidae gen. et
sp. indet. (glatte Art).

Maße:
d N H Q Z
Holotypus B. St. M. 1978 II 176 6,30 cm 959,5 21 _ 52
5,64 5955 22 1,03 46
52 56,0 22 0,9 42
Paratypus 181 6,15 59 22 0,96
Paratypus 179 4,5 60 52
Paratypus 178 5,3 60 20,5 1,05
Paratypus 4,3 56 2355 154
Paratypus 180 ca. 4,7 54 25 1,075
Paratypus 177 752 59 2165 1,13 (Schale)
1,03 _ (Steinkern)
Paratypus 190 6,5 61 20,8 0,98
5,2 55 2255 0,88
4,1 51 28,0 1,0
Paratypus 191 3,9 31,3 26,0 30
Paratypus 200 3,85 55 24 0,85 bis 0,9
Paratypus 201 4,2 56 21,5

Beschreibung des Holotypus: Besonders die in-
neren Windungen sind seitlich komprimiert und mit Kal-
zit ausgefüllt, auf der linken Seite besser als auf der rechten
Seite erhalten. Der letzte Umgang gehört der Wohnkam-
mer an. Die relative Nabelweite nimmt während der On-
togenese zu und ist beim letzten Umgang sehr groß. Die
Windungen überdecken sich nur wenig. Der Windungs-
querschnitt des letzten Umgangs ist subquadratisch.

Die Rippenzahl pro Umgang ist relativ klein. Jede
zweite der rectoradiaten Flankenrippen trägt einen Stachel
(Schale) oder Knoten (Steinkern). Von den Stacheln oder

Knoten gehen je 2 Externrippen aus, von denen jedoch
häufig eine auf der anderen Seite auf eine Schaltrippe trifft,
die nicht aufspaltet. Dadurch entsteht ein Zick-Zack-Mu-
ster. Auf dem letzten Viertel des Wohnkammer-Umgangs
treten etwas retroradiate, fibulate Rippenpaare auf, und
die Rippen stehen etwas dichter.

Die Lobenlinie konnte nicht gezeichnet werden.

Beschreibung der Paratypen: Die Paratypen der
Quebrada El Bolito sind bis auf Exemplar B. St. M. 1978
II 177 seitlich etwas komprimiert (Taf. 8, Fig. 10), ob-

Nabelweite in % vom ®

1 2 3
Gehause 8 incm

Abb. 24: Änderung der relativen Nabelweite im Verlauf der Ontogenie bei Collina chilensis n. sp.: @
B. St. M. 1978 II 176 (Holotypus); + B. St. M. 1978 II 190.

wohl der Phragmokon häufig mit Kalzit ausgefüllt ist. Die
Kompression macht sich bei den innersten Umgängen am
stärksten bemerkbar.

Offensichtlich erfolgte zunächst ein Ausfüllung der
Wohnkammer mit Sediment, dann eine seitliche Kom-
pression mit Verkleinerung des Phragmokon-Hohlrau-
mes und erst anschließend eine Ausfüllung dieses Hohl-
raumes mit Kalzıt. Die Wohnkammern der Exemplare
von der Quebrada EI Bolito besitzen einen subquadrati-
schen Querschnitt.

Die Exemplare vom Rio Pulido sind nur zum Teil seit-
lich komprimiert. Das zur Hälfte erhaltene Exemplar B.
St. M. 1978 II 190 wurde angeschliffen und gezeichnet
(Abb. 23a). Wie bei den Exemplaren der Quebrada El Bo-
lito nimmt während der Ontogenie die relative Nabel-
weite zu (Abb. 24) und ist beim letzten Umgang sehr
groß. Auch der Windungsquerschnitt verändert sich wäh-
rend der Ontogenese. Bis zu einem Durchmesser von
1,5 cm ist der Querschnitt sehr viel breiter als hoch und
wird dann allmählich subquadratisch.

Exemplar B. St. M. 1978 II 179 (Taf. 8, Fig. 9) von der
Quebrada EI Bolito ist bei gleichem Durchmesser weitna-
beliger als die übrigen Exemplare. Zumindest ein Teil des
letzten Umgangs gehört bereits der Wohnkammer an, und
es treten auch fibulate Rippen auf. Es dürfte sich um ein
ausgewachsenes Exemplar mit kleinerem Enddurchmes-
ser handeln.

Die innersten Umgänge sind bei keinem Exemplar er-
halten. Jede zweite der vorwiegend rectoradiaten,
manchmal etwas retroradiaten und nicht dicht stehenden
Flankenrippen trägt einen Stachel oder Knoten. Die
Schaltrippen bleiben einfach, während die Stachel bzw.
Knoten tragenden Rippen bifurkat aufspalten. Ein Zick-
Zack-Muster ist bei einigen Exemplaren vorhanden. Be-
sonders die vorderen durch Bifurkation entstandenen Ex-
ternrippen können nach vorn gebogen sein. Nach einer
halben Windung Wohnkammer können die ersten fibula-
ten Flankenrippen auftreten, die dichter als die vorherge-
henden Rippen stehen. Die fibulaten Rippenpaare spalten
bifurkat auf, zwischen ihnen können Schaltrippen liegen,
die nicht aufspalten.

Exemplar B. St. M. 1978 II 177 (Taf. 8, Fig. 10) ist mit
einem Durchmesser von 7,2 cm größer als die übrigen Ex-
emplare. Die zweite Hälfte des erhaltenen Umgangs weist
fibulate Berippung auf. Bei Schalenerhaltung werden hier
die Rippen auf der Mitte der Externseite doppelt so hoch
wie auf den Flanken. Die fibulaten Rippen spalten eben-
falls in je2 Externrippen auf. Auch auf Phragmokonen mit
Schale sind die kräftigen Rippen auf der Externseite zu-
mindest ebenso hoch wie auf den Flanken.

Das Wohnkammerexemplar (280° erhalten) von der
Quebrada EI Corral (B. St. M. 1978 II 201) (Taf. 8,
Fig. 11) ist kleinwüchsig. Zu Beginn der Wohnkammer
beträgt der Q-Wert 0,9. Auch bei den Windungsbruch-

stücken handelt es sich ausschließlich um Teile der Wohn-
kammer.

Der Windungsquerschnitt ist subquadratisch oder we-
nig breiter als hoch. Die flachen Flanken tragen mehr oder
minder rectoradiate Rippen, die häufig in einem Knoten
zu fibulaten Rippenpaaren vereinigt sind und zwischen
denen Schaltrippen stehen können. Bei Einfachrippen
trägt — soweit erkennbar — jede zweite Flankenrippe ei-
nen Knoten. Von den Knoten gehen zwei Externrippen
aus, manchmal ist auch nur eine Externrippe wie bei den
Schaltrippen vorhanden. Bei dem Exemplar von der Que-
brada Yerbas Buenas (B. St. M. 1978 II 200, Taf. 8,
Fig. 12) ist ebenfalls nur die Wohnkammer (ca. 3, KUm-
gang) gut erhalten. Es treten jedoch keine fibulaten Rip-
penpaare auf. Die Knotenrippen spalten in 2, selten 3 Ex-
ternrippen auf. Die Schaltrippen bleiben zumeist einfach.

Die Lobenlinie konnte bei keinem Exemplar gezeichnet
werden.

Vergleiche: Zu Collina gemma besteht große Ähn-
lichkeit. Collina chilensis n. sp. fehlt jedoch die kielartige
Erhöhung auf der Externseite. Collina kampemorpha
Korrek ist in der Seitenansicht ebenfalls ähnlich.

Diese Art besitzt aber einen etwas breiteren Windungs-
querschnitt, und von den Knoten der Flankenrippen ge-
hen 3 bis 4 Externrippen aus. Die Externseite ist also sehr
viel dichter berippt.

Peronoceras pacificum besitzt einen ähnlichen Win-
dungsquerschnitt, jedoch ist die Externseite stärker ge-
wölbt und bei dieser Art ist bei gleichem Durchmesser die
Flankenrippenzahl pro Umgang größer.

3.4.2 Collina sp.
Taf. 8, Fig. 5; Abb. 19

Material: Quebrada Larga (Abb. 7); topogr. Karte
1:100000, Blatt Carrera Pinto: x = 432,75 km, y =
6978,7 km. Ein unvollständig erhaltenes Exemplar (z. T.
beschalt) (B. St. M. 1978 II 209) (Taf. 8, Fig. 5;
Abb. 19b), 2 Windungsbruchstücke (B. St. M. 1978 II
210 u. 211). Zusammen mit Peronoceras cf. planiventer,
P. cf. crassicostatum, Polyplectus sp., Osperlioceras sp.,
Phymatoceras ex gr. P. erbaense, Hildoceratidae gen. et
sp. indet. (3 Arten).

Beschreibung: Das Exemplar B. St. M. 1978 I1 209
ist bis zu einem Durchmesser von 8 mm vollständig erhal-
ten, dann nur noch ca. '/); der Windungen. Der Win-
dungsquerschnitt ist in den inneren Windungen sehr viel
breiter als hoch, bei der letzten Windung subquadratisch.
Ab einem Durchmesser von ca. 5 mm sind die Flanken-
rippen zu erkennen, von denen jede in einem Stachel en-
det. Auch in den folgenden Windungen ist jede Flanken-
rippe mit einem Stachel oder Knoten versehen. Die letzte
Windung (110° erhalten) gehörtder Wohnkammer an. Die
Flankenrippen spalten bifurkat auf oder bleiben einfach
(unregelmäßig jede zweite). Wie bei Collina chilensis sind
bei Schalenerhaltung die Externrippen der Wohnkammer
in der Mitte höher als an den Seiten und etwas nach vorn
gebogen.

Vergleiche: Collina sp. unterscheidet sich von C.
chilensis durch die geringere Größe, die kleinere relative
Nabelweite und die größere Windungsbreite am Ende des
Phragmokons. Außerdem ist bei Collina sp. wie bei Pe-
ronoceras cf. planiventer und P. cf. crassicostatum (glei-
cher Fundpunkt!) jede Flankenrippe mit einem Stachel
versehen.

4. BIOSTRATIGRAPHISCHE FOLGERUNGEN

Unter-Toarcium (SCHMIDT-Erring), vgl. Abb. 25

v. Hırıesranr legte, zuletzt 1973b (Tab. 1), eine de-
taillierte biostratigraphische Gliederung vom Hettangium
bis Aalenium der chilenisch-argentinischen Hochkordil-
lere vor, die durch die hier vorgelegte monographische
Bearbeitung der Arten von Dactylioceras und Nodicoelo-
ceras für das Unter-Toarcium ergänzt und verfeinert
wird. Da bisher keine Bearbeitung der Ammoniten des
Unter-Toarciums Südamerikas vorliegt und auch das hier
untersuchte Material vorwiegend nur Einzelfaunen aus
neun teilweise weit auseinander liegenden Profilen
repräsentiert, ist eine Zonengliederung zunächst nur indi-
rektdurch Vergleich mit den klassischen stratigraphischen
Abfolgen außerhalb Südamerikas, besonders von Europa,
erschließbar. Doch läßt sich mit Hilfe der vorliegenden
Faunen für das Unter-Toarcium, in Anlehnung an die in-

ternationale Gliederung, folgende biostratigraphische
Zonierung durchführen:

4.1 Zone des DACTYLIOCERAS
(ORTHODACTYLITES) TENUICOSTATUM

Diese weltweit angewandte erste Zone des Toarciums
ist eine Zone sensu abstracto (vgl. HöLper 1964: 27). Sie
wird auch Standardzone genannt und ist mit der OpreL-
Zone vergleichbar (HöLper & Zeıss 1972: 389), d. h., die
Zonen-Art tritt nur in einem Teil der nach ihr benannten
Zone auf. Definitionsgemäß fällt der Beginn dieser Zone
mit der Grenze Pliensbachium/Toarcium zusammen
(Eımi et al. 1974; HowArTH 1973, 1978). In Chile ist diese
Zone in zwei Subzonen (= Zonen sensu concreto, HOL-
DER 1964) gliederbar:

4.1.1 Subzone des Dactylioceras (Eodactylites)
simplex

Diese Subzone ist von der Quebrada Chanchoquin und
Quebrada El Penon bekannt:

a) Quebrada Chanchoquin:

Dactylioceras (Eodactylıtes) sımplex (9 Exemplare),
Dactylioceras (Orthodactylites) directum (6 Exemplare),
Dactylioceras (Orthodactylites) angninum (2 Exemplare),
Nodicoeloceras cf. eikenbergi (1 Exemplar),
Nodicoeloceras cf. pseudosemicelatum (5 Exemplare),

b) Quebrada El Penon:

Dactylioceras (? Eodactylites) sp.
Nodicoeloceras cf. eikenbergi

Von diesen Arten treten D. anguinum und D. direc-
tum ım gesamten Unter-Toarcium auf, während die rest-
lichen drei das tiefste Unter-Toarcıum charakterisieren,
wobei D. (Eodactylites) grundsätzlich auch schon im
höchsten Domerium vorhanden ist. Nach HowArTH
(1973, 1978) treten Formen, die mit den beiden hier ge-
fundenen Nodicoeloceras-Arten ıdent oder doch sehr nahe
stehen, als Leitformen in der ‚‚clevelandicum“ -Subzone
der tenuicostatum-Zone in Yorkshire auf, indem sie dort
die ältesten Dactylioceraten ‘überhaupt stellen. Nach
Horrmann (1968: 9) tritt N. eikenbergi in der tieferen te-
nuicostatum-Zone (siemensis-Subzone) auf, ebenfalls N.
pseudosemicelatum innerhalb eines ähnlichen stratigra-
phischen Bereichs (MAuseuce 1957: 193).

HOWARTH 1978

Das Vorkommen von D. (Eodactylites) zeigt tiefstes
Unter-Toarcium aber auch höchstes Domerium an (Ho-
WARTH 1978: 252; SCHMIDT-EFFING 1972: 180); hier ist je-
doch durch das gemeinsame Auftreten mit den genannten
Arten von Dactylioceras (Orthodactylites) und Nodicoe-
loceras Untertoarcium-Alter sichergestellt.

Eımi, Arrops & Mancoıp (1974: 55), ähnlich auch
Gurx (1973 a: 512), scheiden als tiefsten Abschnitt der te-
nuicostatum-Zone in der mediterranen Provinz eine Sub-
zone des D. (E.) mirabile aus. Da im gesamten Abschnitt
der mirabile-Subzone, wie auch in dem zeitlich äquivalen-
ten Bereich der tieferen tenuicostatum-Zone der nord-
west-europäischen Provinz noch nie ein D. tennicostatum
gefunden wurde, ist es wenig sinnvoll, diese Subzone zur
tenuicostatum-Zone zu stellen. Vielmehr wäre dieser Ab-
schnitt im Mediterran als mirabile-Zone — im Hangenden
folgt die semicelatum-Zone, da D. tenuicostatum hier
auch in der höheren ‚‚tenuicostatum-Zone‘‘ kaum auftritt
(Eımi et al. 1974) — auszuscheiden. Die tennicostatum-
Zone, so wıe sie in Yorkshire ausgeschieden wurde (Ho-
WARTH 1973), widerspricht den stratigraphischen Richtli-
nien (1977: 135) wie auch dem stratigraphischen Ver-
ständnis. Die Basis einer Zone wird durch das Erstauftre-
ten der Zonen-Leitart definiert, doch die Leitart tritt in
den Yorkshire-Profilen nur zu Anfang des obersten Drit-
tels der Gesamtzone auf. Die internationale Zonengliede-
rung des Unter-Toarciums ist also noch wenig ausgereift.

Da in Chile bis jetzt nur Dactylioceras (Eodactylites)
simplex, nicht aber D. (E.) mirabile bekannt ist, schlage
ich vor, diesen Abschnitt simplex-Subzone zu benennen.
Sie dürfte ziemlich exakt der mirabile-Zone des mediter-
ranen Bereiches entsprechen.

ELMI, ATROPS &

MANGOLD 1974

falcıfer -
Subzone

exaratum -

falcıfer -

Subzone

serpentinus-Z.

semicelatum -
Subzone

tenuicostatum-
Subzone

clevelandicum -
Subzone

tenuicostatum -

paltum-

tenuicostatum - Zone

Subzone

Abb. 25:

(strange-
waysi-Sz)

semicelatum -
Horizont

mirabıle -
Horizont

(mulgravium -

Subzone)

hoelderi - Zone

serpentinif-H.
elegantulum-H

tenuicostatum-
Subzone

simplex -
Subzone

tenuicostatum-Zone

Biostratigraphische Gliederung des Unter-Toarciums.

4.1.2 Subzone des Dactylioceras (Orthodactylites)
tenuicostatum
Diese Subzone ist aus fünf verschiedenen chilenischen
Profilen bekannt und zwar mit folgender Fauna:

a) Quebrada EI Bolito:

Dactylioceras (Orthodactylites) tennicostatum chilense (4
Exemplare),

b) Rio Manflas (bei Los Graneros):

Dact. (Orthodactylites) tenuicostatum chilense (1 Exem-
plar),

Dact. (? Orthodactylites) cf. helianthoides (1 Exemplar),
Dact. (Orthodactylites) sp. (2 Exemplare);

Die drei letzten Exemplare stammen aus etwas jüngeren
Schichten als das aufgeführte D. (O.) tennicostatum chi-
lense.

c) Rio Manflas (bei Portezuelo EI Padre):
Dact. (Orthodactylites) tennicostatum chilense (1 Exem-
plar),

d) Quebrada La Chaucha:

Dact. (Orthodactylites) tenuicostatum chilense (2 Exem-
plare),

Dact. (Orthodactylites) cf. directum (1 Exemplar),
Dact. sp. juvenil (1 Exemplar).

e) Quebrada El Penon:

Dact. (Orthodactylites) tenuicostatum chilense (10 Exem-
plare),

Dact. (? Orthodactylites) helianthoides (1 Exemplar),
Nodicoeloceras sp. (1 Exemplar).

Das Alter dieser Fauna ist durch das Vorkommen von
Dactylioceras tenuicostatum, das hier durch eine beson-
dere Unterart vertreten wird, mit den klassischen europä-
ischen Profilen direkt korrelierbar. Es entspricht der te-
nuicostatum-Subzone der tennicostatum-Zone von Ho-
WARTH (1973: 241). Entsprechend den Stratigraphischen
Richtlinien (1977: 135, $ 3.2.9) sollte dieser Abschnitt, in
welchem die Leitart tatsächlich auftritt, entgegen der bis-
herigen internationalen Gepflogenheit tennicostatum-
Zone genannt werden.

4.2 Zone des DACTYLIOCERAS
(ORTHODACTYLITES) HOELDERI!

Diese Zone ist aus fünf chilenischen Profilen bekannt
und zwar mit folgender Fauna:

a) Quebrada Yerbas Buenas:

Dactylioceras (Orthodactylites) hoelderi (5 Exemplare),
Dact. (Orthodactylites) directum (1 Exemplar),

Dact. (Orthodactylites) cf. directum (4 Exemplare),
Nodicoeloceras cf. crassoides Form A (4 Exemplare);

b) Quebrada EI Asiento:

Dact. (Orthodactylites) anguinum (2 Exemplare),

Dact. (? Orthodactylites) cf. helianthoides (3 Exemplare),
Nodicoeloceras cf. crassoides Form B (1 Exemplar),
Nodicoeloceras cf. crassoides Form C (1 Exemplar);

c) Rio Jorquera (Majada del Carrizo):
Dact. (Orthodactylites) directum (4 Exemplare),

Dact. (Orthodactylites) cf. directum (3 Exemplare),
Nodicoeloceras cf. crassoides Form C (7 Exemplare);

d) Quebrada Noria:

Dact. (Orthodactylites) hoelderi (1 Exemplar),
Dact. (Orthodactylites) directum (4 Exemplare),
Dact. (? Orthodactylites) helianthoides (20 Exemplare);

e) Quebrada Calquis:

Dact. (Orthodactylites) cf. hoelderi (2 Exemplare),
Nodicoeloceras cf. crassoides Form A (1 Exemplar);

Dactylioceras directum und Dact. anguinum treten ım
gesamten Unter-Toarcium auf, während die übrige Fauna
innerhalb dieses Zeitabschnittes zeitspezifischen Charak-
ter besitzt. Nodicoeloceras cf. crassoides charakterisiert
vorwiegend das höhere Unter-Toarcium, in England be-
sonders die falcifer-Zone. Dact. (? Orthodactylites) he-
lianthoides ist für diese Zone in Chile sehr bezeichnend,
doch tritt es in Japan im gesamten Unter-Toarcium und
auch schon im höheren Domerium auf, so daß bei biostra-
tigraphischer Datierung mit dieser Art, wenn sie alleine
auftritt, Vorsicht geboten sein sollte. Mit Hilfe der ende-
mischen Art Dact. (Orthodactylites) hoelderi ist jedoch
eine gute Biozone ausgliederbar. Zeitlich entspricht diese
Zone im wesentlichen dem höheren Abschnitt der semice-
latum-Subzone der tennicostatum-Zone und der falci-
fer-Zone Europas und des Mediterrans.

Eine Zonenbenennung nach Harpoceras oder ähnli-
chen Formen, wie das besonders in NW-Europa prakti-
ziert wird, sollte vermieden werden, da diese weltweit
nicht nur sehr unterschiedlich, sondern vor allen Dingen
auch stratigraphisch noch viel höher und tiefer häufig auf-
treten (vgl. SCHMIDT-ErrinG 1972: 181; Ermı, ATROPS &
Mancoıp 1974). Mit der hoelderi-Zone schließt das chi-
lenische Unter-Toarcium ab.

Mittel-Toarcium (von Hırıesranpr), vgl. Abb. 26.

4.3 ZONE DES HILDOCERAS BIFRONS

In den letzten Jahren hat es mehrere Versuche gegeben,
die Zone des Hildoceras bifrons in Subzonen zu untertei-
len, sowohl im NW-europäischen Bereich, als auch im
Mediterrangebiet.

Dean, Donovan & HowarTH (1961) stellten eine Zo-
nengliederung für die NW-europäische Provinz auf und
unterteilten die bifrons-Zone in die Subzonen des Dacty-
lioceras commune, Peronoceras fibulatum und Zugodac-
tylites braunianum. Diese Gliederung wurde für diesen
Bereich auch von späteren Autoren übernommen.

Donovan (1958) gab für die Südalpen und den Apennin
eine Zonengliederung. Seine Zone des Mercaticeras mer-
cati entspricht der bifrons-Zone. Die mercati-Zone un-
terteilte er in die Subzonen des Hildoceras sublevisoni und
Hıldoceras semipolitum.

Gasırry etal. (1971) stellten für den Stratotyp des Toar-
cıum (Thouars) und die benachbarten Gebiete eine Zo-
nengliederung auf. Die bifrons-Zone wird von Ihnen un-
terteilt in die Subzonen des Hildoceras sublevisoni, Hildo-
ceras bifrons und Hildoceras semipolitum. Die subleviso-
ni-Subzone wird zusätzlich unterteilt in die Horizonte des
Hildoceras sublevisoni, Dactylioceras commune und Hiıl-
doceras lusitanicum.

Eımi, Arrops & Manor (1974) unterscheiden inner-
halb der bifrons-Zone 4 Subzonen; die Subzonen des Hil-
doceras sublevisioni, H. lusitanicum, H. bifrons und H.
semipolitum.

HowarTH (1978) stellte fest, daß in England (North-
hamptonshire und Yorkshire) Peronoceras fibulatum
und Zugodactylites braunianum zusammen vorkommen.
Er untergliedert deshalb die bifrons-Zone ın die Subzonen
des Dactylioceras commune, Peronoceras fibulatum und
Catacoeloceras crassum.

Die Subzone des Dactylioceras commune ist gleichaltrig
mit der Subzone des Hıldoceras sublevisioni (bzw. H. su-
blevisioni und H. lusitanicum bei Eımi, Arrops & MaAn-
soLD), die Subzone des Peronoceras fibulatum entspricht
der Subzone des Hildoceras bifrons und die Subzone des
Catacoeloceras crassum kann mit der Subzone des Hildo-
ceras semipolitum verglichen werden.

Zur Untergliederung der bifrons-Zone werden also in
Europa Arten der Gattung Hildoceras oder Arten ver-
schiedener Gattungen der Dactylioceratidae herangezo-
gen. Bei einem Vergleich mit Südamerika ergibt sich die
Schwierigkeit, daß die Gattung Hildoceras bisher in Süd-
amerika nicht nachgewiesen wurde, ebenso die Gattungen
Dactylioceras s. str. und Zugodactylites fehlen. Die Gat-
tung Catacoeloceras ist selten und es liegen bisher keine
artlich bestimmbaren Exemplare vor. Arten der Gattun-

gen Peronoceras (+ Porpoceras) und Collina sind hinge-
gen weit verbreitet und mit ihnen ist eine Unterscheidung
mehrerer Faunenzonen möglich.

In England (HowarTtH 1978) erscheint die Gattung Pe-
ronoceras an der Basis der fibulatum-Subzone. In Frank-
reich (GAsıtLy 1976) tritt diese Gattung bereits ab der Ba-
sis der sublevisoni-Subzone auf. In Portugal (MOUTERDE
1967), Algerien (Eımı, Arrops & ManGoLp 1974) und Ma-
rokko (Gurx 1973) treten die ersten zur Gattung Perono-
ceras zu rechnenden Arten bereits in der serpentinus-
bzw. levisoni-Zone auf. Beide Zonen sind mit der falcı-
fer-Zone gleichaltrig. Im Mediterranbereich erscheint.also
die Gattung Peronoceras früher als in der NW-europä-
ischen Provinz.

In den Schichten, die altersmäßig denen der bifrons-
Zone in Europa entsprechen, lassen sich in Chile mit Hilfe
von Arten der Gattungen Peronoceras und Collina 3 Sub-
zonen unterscheiden.

4.3.1 Subzone des Peronoceras largaense

Diese Subzone ist aus 6 chilenischen Profilen bekannt
und zwar mit folgender Fauna:

a) Quebrada Larga (Abb. 7, Schicht 8)

Peronoceras largaense (Holotypus)
Peronoceras cf. subarmatum
Harpoceras sp.

Mercaticeras sp.

b) Quebrada El Bolito (Abb. 5, Schicht 6)

Peronoceras largaense
Peronoceras cf. subarmatum
Harpoceras cf. chrysanthemum
Mercaticeras sp.

c) Rio Jorquera (Majada del Carrizo) (Abb. 9)
Schicht 7a:

Peronoceras largaense
Peronoceras cf. subarmatum
Harpoceras sp.

Schicht 8:

Peronoceras cf. renzi
Peronoceras sp.
Harpoceras sp.

d) Quebrada Yerbas Buenas (Abb. 6, Schicht 8)

Peronoceras cf. desplacei

Peronoceras cf. choffati

Peronoceras sp. ex gr. P. subarmatum
Harpoceras cf. chrysanthemum

e) Quebrada EI Asiento (Abb. 3, Schicht 5)

Peronoceras cf. subarmatum

Harpoceras cf. falcifer

f) Quebrada La Chaucha

Peronoceras cf. renzi

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Der biostratigraphische Vergleich der largaense-Zone
mit gleichaltrigen Schichten in Europa ist schwierig, da
der tiefere Teil der bifrons-Zone dort durch Arten charak-
terisiert wird, die in Südamerika nicht auftreten und von
denen auch keine nahe verwandten Formen vorhanden
sind. Peronoceras cf. subarmatum ist zwar nahe ver-
wandt mit P. subarmatum, das jedoch in England nach
HOowARTH (1978) nur im unteren Teil der fibulatum -Sub-
zone vorkommt. Peronoceras choffati tritt nach Mou-
TERDE (1967) bereits in der serpentinus-Zone auf. Perono-
ceras desplacei ist in Europa eine Art der bifrons- bzw. fi-
bulatum-Subzone. Der genaue Faunenhorizont von Pe-
ronoceras renzi innerhalb der bifrons-Zone ist nicht be-
kannt. Harpoceras chrysanthemum kommt nach Dacıs
(1974) in der commune-Zone vor.

Das Harpoceras cf. falcifer aus der Quebrada EI
Asiento ist eine engnabelige Varietät dieser Art, die in
Frankreich nach Gasıtry (1976) in der sublevisoni-Sub-
zone auftritt.

Am Rio Jorquera, in der Quebrada Yerbas Buenas und
in der Quebrada El Asiento wird die largaense-Subzone
von Schichten mit einer Fauna der hoelderi-Zone unterla-
gert und in der Quebrada EI Bolito, Quebrada Yerbas
Buenas und Quebrada El Asiento von Schichten mit einer
Fauna der pacıficum-Subzone überlagert.

4.3.2 Subzone des Peronoceras pacificum

Diese Subzone ist aus 4 Profilen in Chile bekannt, die
folgende Fauna enthalten:

a) Quebrada Yerbas Buenas (Abb. 6, Schicht 9)

Peronoceras pacificum
Peronoceras cf. verticosum
Peronoceras cf. P. cf. verticosum
Maconiceras sp.

Polyplectus sp.

b) Quebrada Potrerillos (Abb. 1, Profil 10)

Peronoceras pacıificum (Holotypus)
Peronoceras cf. verticosum
Harpoceras sp.

Maconiceras sp.

c) Quebrada EI Bolito (Abb. 5, Schicht 7)

Peronoceras pacificum
Harpoceras sp.
Maconiceras sp.
Polyplectus sp.

d) Quebrada El Asiento

Peronoceras cf. verticosum
Harpoceras sp.

Peronoceras pacıficum ist nahe verwandt mit Peronoce-
ras vorticellum. Peronoceras vorticellum und P. vertico-
sum kommen nach HowarTtH (1978) in England und S-
Frankreich (nach Gurx 1972) im oberen Teil der fibula-

tum-Subzone vor. Die Gattung Phymatoceras ist in der
pacificum-Subzone noch nicht vorhanden, tritt jedoch in
England und S-Frankreich bereits im oberen Teil der fibu-
latum-Subzone auf. Die pacificum-Subzone umfaßt daher
wahrscheinlich nur den tieferen Teil der fibulatum- bzw.
bifrons-Subzone.

4.3.3 Subzone der Collina chilensis

Nach Fischer (1966), Pınna & Levi-Serti (1971) und
Gurx (1972) beginnt die Gattung Collina in der obersten
Subzone der bifrons-Zone und reicht bis in die vanzabı-
lis-Zone. GALLITELLı WENDT (1969), ATRops & Eımi (1971)
und Eımı, Arrops & Mancoıp (1974) stellten eine Sub-
zone der Collina gemma auf. Eımı, Arrops & MAnGoLD
vergleichen diese Zone mit dem tiefsten Teil der variabi-
lıs-Zone in England und Frankreich. GarırteLı WENDT
gibt jedoch zusammen mit Collina gemma verschiedene
Arten der Gattung Peronoceras an. ELm1, ATROPs & Man-
coLD fanden in den Schichten der semipolitum-Subzone
keine Dactylioceratidae. Da es sich bei Collina chilensis
wahrscheinlich um einen frühen Vertreter dieser Gattung
handelt, dem noch die kielartige Erhöhung auf der Extern-
seite fehlt, und da C. chilensis zusammen mit Vertretern
der Gattung Peronoceras vorkommt, ist ein Vergleich der
chilensis-Subzone mit der crassum-Subzone im Sinne von
HowarTH (1978) wahrscheinlicher als ein Vergleich mit
dem tieferen Teil der variabılıs-Zone. Innerhalb der chi-
lensis-Subzone können zwei Faunenhorizonte unter-
schieden werden. In beiden Horizonten kommt C. chi-
lensis vor. Der tiefere Horizont wird durch Peronoceras
bolitoense und P. cf. vortex und der höhere Horizont
durch Peronoceras moerickei und P. cf. bolitoense cha-
rakterisiert. Die Peronoceras-Exemplare im höheren Ho-
rizont sind großwüchsiger als im tieferen Horizont. Pero-
noceras moerickei und P. cf. bolitoense sind sehr viel
großwüchsiger als alle bisher bekannten Arten dieser Gat-
tung.

4.3.3.1 Horizont mit Peronoceras bolitoense

Dieser Horizont kommt bei folgenden chilenischen
Profilen vor:

a) Quebrada El Bolito (Abb. 5, Schicht 8)

Peronoceras bolitoense (Holotypus)

Collina chilensis (Holotypus)

Harpoceras sp.

Maconiceras sp.

Phymatoceras sp.

Hildoceratidae gen. et sp. indet. (glatte Art)

b) Quebrada Cortaderita (Abb. 1, Profil 8)

Peronoceras cf. vortex

Peronoceras sp. ex gr. P. bolitoense

Collina chilensis

Harpoceras cf. subexaratum

Phymatoceras ex gr. P. erbaense
Hildoceratidae gen. et sp. indet. (glatte Art)

c) Rio Manflas (Profil zum Portezuelo El Padre) (Abb. 1,
Profil 16)

Peronoceras bolitoense

Peronoceras sp.

Collina cf. chilensis

Polyplectus sp.

Hildoceratidae gen. et sp. indet. (glatte Art)

d) Quebrada Llareta (Abb. 1 Profil 13)

Peronoceras cf. vortex
Maconiceras sp.
Polyplectus sp.
Phymatoceras sp.

e) Rio Jorquera (Vegas de Chanar) (Abb. 1, Profil 14a)

Peronoceras cf. bolitoense

Peronoceras cf. P. cf. vortex

Collina chilensis

Harpoceras cf. subexaratum

Hildoceratidae gen. et sp. indet. (glatte Art)

f) Quebrada Paipote bei Redonda (Abb. 4, Schicht 3)

Peronoceras sp. ex gr. P. cf. verticosum
Peronoceras cf. bolitoense

Collina chilensıis

Hildoceratidae gen. et sp. indet. (2 Arten)

g) Quebrada Yerbas Buenas (Abb. 6)

Peronoceras cf. bolitoense

Collina chilensis

Maconiceras sp.

Hildoceratidae gen. et sp. indet. (glatte Art)

Der Horizont mit Peronoceras bolitoense kann mitdem
oberen Teil der fibulatum-Subzone und dem tieferen Teil
der crassum-Subzone in Europa verglichen werden, da in
diesem Horizont erstmals die Gattung Phymatoceras auf-
tritt.

4.3.3.2 Horizont mit Peronoceras moerickei

Dieser Horizont wurde bei folgenden Profilen gefun-
den:

a) Juntas del Toro (Abb. 10, Schicht 7)

Peronoceras cf. bolitoense

Collina chilensis

Harpoceras cf. subexaratum
Phymatoceras sp.

Hildoceratidae gen. et sp. indet. (2 Arten)

b) Salto del Toro (Abb. 10, Schicht 9)

Peronoceras cf. bolitoense

c) Rio Pulido (Abb. 10)

Peronoceras cf. bolitoense

Collina chilensıs

Harpoceras cf. subexaratum

Hildoceratidae gen. et sp. indet. (glatte Art)

d) Quebrada El Asiento (Abb. 3, Schicht 6 u. 7)

Peronoceras moerickei (Holotypus)
Collına sp.
Catacoeloceras sp.

e) Salar de Pedernales (Abb. 1, Profil 1)

Peronoceras moerickei

Harpoceras cf. subexaratum

Maconiceras sp.

Hildoceratidae gen. et sp. indet. (2 Arten)

f) Quebrada Yerbas Buenas (Abb. 6)

Peronoceras moerickei

g) La Guardia

Peronoceras moerickei

h) Quebrada El Corral (Quebr. La Totora) (Abb. 1, Pro-
fil 20)

Collina chilensis

Catacoeloceras (?) sp.

Harpoceras cf. subexaratum

Hildoceratidae gen. et sp. indet. (2 Arten)

i) Quebrada EI Bolito (Abb. 5, Schicht 9 u. 10)

Phymatoceras cf. erbaense
Hildoceratidae gen. et sp. indet. (3 Arten)

k) Quebrada Larga (Abb. 7, Schicht 9)

Peronoceras cf. planiventer

Peronoceras cf. crassicostatum

Collına sp.

Polyplectus sp.

Osperlioceras sp.

Phymatoceras ex gr. P. erbaense
Hildoceratidae gen. et sp. indet. (3 Arten)

Der Horizont mit Peronoceras moerickei kann mit dem
oberen Teil der crassum-Subzone in Europa verglichen
werden.

Die Fauna der Schicht 9 von der Quebrada Larga unter-
scheidet sich von der der übrigen Lokalitäten. Sie gehört
möglicherweise bereits der varzabilis-Zone an.

Bei den Profilen Juntas del Toro, Quebrada Larga,
Quebrada El Corral und La Guardia liegen unmittelbar
über dem letzten Horizont mit Dactylioceraten Schichten
mit Phymatoceras cf. fabale und Phymatoceras cf. lilli.
Diese Schichten können nicht mehr zur bifrons-Zone ge-
rechnet werden und dürften gleichaltrig mit denen der va-
riabilis-Zone in Europa sein.

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— — (1969): Revisione delle Ammoniti figurate da GUISEPPE
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PınnA, G. & LEvI-SETTI, F. (1971): I Dactylioceratidae della

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SCHMIDT-EFFING, R. (1972): Die Dactylioceratidae, eine Am-
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zoikum des nördlichen Bayern. - Erlanger geol. Abh., 90:
3140, 1 Tab.; Erlangen.

Fig.

1-4:
ka,b:

Tafel

Dactylioceras (Eodactylites) simplex Fucını, 1935

Phragmokon und Teil der Wohnkammer in Schalenerhaltung; Quebrada Chanchoquin;
B. St. M. 1978 II 4; a: Lateral-, b: Frontalansicht; nat. Gr.

Phragmokon in Schalenerhaltung; Quebrada Chanchoquin; B.St.M. 1978 II 5; a: Lateral-,
b: Ventralansicht; nat. Gr.

Teile von 5 Umgängen des Phragmokons in Schalenerhaltung; Quebrada Chanchoquin;
B. St. M. 1978 II 7; Lateralansicht; nat. Gr.

Phragmokon in Schalenerhaltung; Quebrada Chanchoquin; B. St. M. 1978 II 6; Lateralan-
sicht; nat. Gr.

Dactylioceras (Orthodactylites) anguınum (REINECKE, 1818).

Steinkern z. T. mit Schale; Quebrada El Asiento; B. St. M. 1978 II 10; Lateralansicht; nat. Gr.

unvollständiger Steinkern mit Schale des Phragmokons und Teilen der Wohnkammer; Que-
brada Chanchoquin; B. St. M. 1978 II 13; a: Lateral-, b: Ventralansicht; nat. Gr.

Teil des Phragmokons in Schalenerhaltung; Quebrada Chanchoquin; a: Lateral-, b: Ventral-
ansicht; 1,5-fach vergr.

Dactylioceras (Orthodactylites) directum (BUCKMAN, 1926).

: Phragmokon weitgehend in Schalenerhaltung; Quebrada Chanchoquin; B. St. M. 1978 II 14;

a: Lateral-, b: Ventralansicht; (teils Sipho sichtbar); nat. Gr.

Steinkern teilweise mit Schale; Quebrada Noria; B. St. M. 1978 II 21; Lateralansicht; 2-fach
vergr.

Steinkern teilweise mit Schale; Quebrada Noria; B. St. M. 1978 II 22; Lateralansicht; nat. Gr.

Steinkern; Quebrada Yerbas Buenas; B. St. M. 1978 II 24; Lateralansicht; nat. Gr.

Dactylioceras (?Orthodactylites) helianthoides YOKOYAMA, 1904.

Phragmokon und Wohnkammer in Schalenerhaltung; Quebrada Noria; B. St. M. 1978 I1 30;
Lateralansicht; nat. Gr.

Steinkern teilweise mit Schale; Quebrada Noria; B. St. M. 1978 IL 31; Lateralansicht; nat. Gr.

Schalenerhaltung; Quebrada Noria; B. St. M. 1978 II 33; a: Lateral-, b: Ventralansicht;
nat. Gr.

Schalenerhaltung; Quebrada Noria; B. St. M. 1978 II 34; Lateralansicht; nat. Gr.

Schalenerhaltung; Quebrada Noria; B. St. M. 1978 II 43; a: Lateral-, b: Ventralansicht;
nat. Gr.

Schalen- und Steinkernerhaltung; Quebrada Noria; B. St. M. 1978 I1 38 und 39 (aufsitzendes
weiteres Fragment); Lateralansicht; nat. Gr.

Schalenerhaltung; Quebrada Noria; B. St. M. 1978 11 47; Lateralansicht; nat. Gr.

Tafel 1

Zitteliana 6, 1980

AR Kon

une

Zitteliana 6, 1980 Tafel 2

Tafel 2

Fig. 1-3u.5: Dactylioceras (Orthodactylites) hoelderi nov. spec.

lasb:

2:2, b:

Fig. 6-8:

Fig. 9a, b:

Holotypus; Phragmokon und Wohnkammer in Schalenerhaltung; Quebrada Yerbas Buenas;
B. St. M. 1978 II 53; a: Lateral-, b: Frontalansicht; nat. Gr.

Teil des Phragmokons in Schalenerhaltung; Quebrada Yerbas Buena; B. St. M. 1978 II 56;

a: Lateral-, b: Ventralansicht; nat. Gr.

Teile des Phragmokons und der Wohnkammer in Schalenerhaltung, auf einem Expl. von
Dactylioceras (?Orthodactylites) helianthoides; Quebrada Noria; B. St. M. 1978 II 60;
Lateralansicht; nat. Gr.

Dactylioceras (?Orthodactylites) cf. helianthoides YOKOYAMA, 1904; Steinkern; Rio Manflas;
B. St. M. 1978 1152; Lateralansicht; nat. Gr.

Schalenerhaltung; Quebrada Yerbas Buenas; B. St. M. 1978 II 57; a: Lateral-, b: Ventralan-
sicht; nat. Gr.

Dactylioceras (Orthodactylites) tennicostatum chilense nov. subspec.

Holotypus; Steinkern der Wohnkammer; Rio Manflas; B. St. M. 1978 II 61; a: Ventral-,
b: Lateralansicht; nat. Gr.

Steinkern-Fragment; Quebrada La Chaucha; B. St. M. 1978 II 68; Lateralansicht: nat. Gr.

Teils limonitiertes Steinkern-Fragment; Quebrada El Bolito; B. St. M. 1978 II 63; Lateral-
ansicht; nat. Gr.

Nodicoeloceras cf. pseudosemicelatum (MAUBEUGE, 1957), Schalenerhaltung; Quebrada
Chanchoquin; B. St. M. 1978 II 77; a: Ventral-, b: Lateralansicht; nat. Gr.

Fig.

Tafel 3

Nodicoeloceras cf. eikenbergi (HOFFMANN, 1968), Schalenerhaltung; Quebrada Chancho-
quin; B. St. M. 1978 11 78; a: Lateral-, b: Ventralansicht; nat. Gr.

Nodicoeloceras cf. crassoides (SIMPSON, 1855) Form A.

Steinkern teils mit Schale; Quebrada Yerbas Buenas; B. St. M. 1978 II 79; a: Lateral-, b: Ven-
tralansıcht; nat. Gr.

Steinkern teils mit Schale; Quebrada Yerbas Buenas; B. St. M. 1978 II 82; a: Ventral-,

b: Lateralansicht; nat. Gr.

Steinkern teils mit Schale; Quebrada Yerbas Buenas; B. St. M. 1978 II 81; Lateralansicht;
nat. Gr.

Nodicoeloceras cf. crassoides (SımPsoN, 1855) Form B; Schalenerhaltung; Quebrada EI
Asiento; B. St. M. 1978 II 84; Lateralansıcht; nat. Gr.

Nodicoeloceras cf. crassoides (SIMPSON, 1855) Form C; Steinkern mit Schalenresten;
Quebrada El Asiento; B. St. M. 1978 II 85; Lateralansicht; nat. Gr.

Peronoceras cf. subarmatum (YOUNG & BIRD, 1822)

7a,b,c: Phragmokon-Steinkern mit Beginn (}) der Wohnkammer; Quebrada El Bolito; B. St. M.

1978 Il 87; a: Lateral-, b: Sagittal-, c: Ventralansicht; nat. Gr.
Wohnkammer-Steinkern; Majada del Carrizo; B. St. M. 1978 II 95; nat. Gr.
Wohnkammer-Steinkern; Majada del Carrizo; B. St. M. 1978 II 97; nat. Gr.

? Wohnkammer-Steinkern; Majada del Carrizo; B. St. M. 1978 II 98; nat. Gr.

Tafel 3

Zitteliana 6, 1980

&
&

7 'h

DRS

Zitteliana 6, 1980 Tafel 4

);

oO ah }
NTCELTER

_
—_

Fig.

7 a,b:

Tafel 4

Peronoceras largaense n. sp.

Holotypus; Phragmokon und Teil der Wohnkammer in Schalenerhaltung; Quebrada Larga;
B. St. M. 1978 II 106; a: Lateral-, b: Ventralansicht; nat. Gr.

Wohnkammer-Steinkern; Quebrada Larga; B. St. M. 1978 II 107; a: Lateral-, b: Ventral-
ansicht; nat. Gr.

Wohnkammer-Steinkern; Quebrada El Bolito; B. St. M. 1978 II 109; a: Lateral-, b: Ventral-
ansicht; nat. Gr.

Wohnkammer-Steinkern (äußerer Umgang); Quebrada Larga; B. St. M. 1978 II 108; nat. Gr.

Peronoceras cf. choffati (RENZ, 1912)

Wohnkammer-Steinkern; Quebrada Yerbas Buenas; B. St. M. 1978 II 119; nat. Gr.
Phragmokon (125° der Umgänge erhalten), angeschliffene Querschnitte; Quebrada Yerbas
Buenas; B. St. M. 1978 II 120; nat. Gr.

Peronoceras cf. desplacei (D’ORBIGNY, 1844)

Phragmokon in Schalenerhaltung; Quebrada Yerbas Buenas; B. St. M. 1978 I 115; a: an-
geschliffener Querschnitt; b: Ventralansicht; nat. Gr.

: Äußerer Umgang Steinkern mit z. T. Schale (? Wohnkammer), innere Umgänge mit Kalzit

ausgefüllter Phragmokon; Quebrada Yerbas Buenas; B. St. M. 1978 II 114; a: Lateral-,
b: Ventralansicht; nat. Gr.

Peronoceras cf. renzi (PINNA & LEVI-SETTI, 1971)
Wohnkammer-Steinkern (T Beginn der Wohnkammer); Quebrada La Chaucha; B. St. M.
1978 IL 118; nat. Gr.

9, 11-16: Peronoceras pacificum n. sp.

9a,b:

lla,b:

Wohnkammer-Steinkern, Phragmokon mit Kalzit ausgefüllt (Oberfläche nicht erhalten);
Quebrada Yerbas Buenas; B. St. M. 1978 II 123; a: Lateral-, b: Ventralansicht; nat. Gr.

Erhaltung wie Fig. 9; Quebrada Yerbas Buenas; B. St. M. 1978 II 122; a: Lateral-,

b: Ventralansicht; nat. Gr.

Phragmokon, z. T. in Schalenerhaltung, Oberfläche der Wohnkammer nicht erhalten;
Quebrada Porrerillos; B. St. M. 1978 II 127; nat. Gr.

Holotypus; Phragmokon (z. T. in Schalenerhaltung) und Wohnkammer (vorwiegend als
Steinkern); Quebrada Potrerillos; B. St. M. 1978 II 125; nat. Gr.

Steinkern mit Schale (nur Ventralseite freipräpariert); Quebrada Yerbas Buenas;
B. St. M. 1978 II 124; nat. Gr.

Erhaltung wie Fig. 9; Quebrada Yerbas Buenas; B. St. M. 1978 II 121; a: Lateral-,
b: Ventralansicht; nat. Gr.

Innenwindungen Phragmokon (in Schalenerhaltung), Außenwindungen Wohnkammer-
Steinkern; Quebrada Potrerillos; B. St. M. 1978 II 126; a, c: Lateral-, b: Sagittalansicht;
a, b: nat. Gr.,c2:1.

Fig.

Soanb:

Tafel5

Peronoceras pacıificum n. sp.

Wohnkammer-Steinkern, Phragmokon als Abdruck (letzte Windung z. T. mit Kalzit ausge-
füllt); Quebrada El Bolito; B. St. M. 1978 II 129; a: Lateral-, b: Frontalansicht; nat. Gr.

Erhaltung wie Fig. 1; Quebrada El Bolito; B. St. M. 1978 II 128; a: Lateral-, b: Ven-
tralansicht; nat. Gr.

Peronoceras sp. ex gr. P. cf. verticosum (BUCKMAN, 1914); Wohnkammer-Stein-
kern (lateral etwas verdrückt); Quebrada Paipote bei Redonda; B. St. M. 1978 II 132;
a: Lateral-, b: Frontalansicht; nat. Gr.

Peronoceras sp. exgr. P. cf. vortex (SIMPSON, 1855); Phragmokon-Innenwindungen (Stein-
kern mit Schalenresten); Quebrada Llaretra; B. St. M. 1978 II 140; nat. Gr.

Peronoceras cf. verticosum (BUCKMAN, 1914); Wohnkammer-Steinkern, Phragmokon mit
Kalzit ausgefüllt (Oberfläche nicht erhalten); Quebrada Yerbas Buenas; B. St. M. 1978 I1 130;
a: Lateral-, b: Ventralansicht; nat. Gr.

Peronoceras sp. cf. P. cf. verticosum (BUCKMAN, 1914); Phragmokon mit Schale,
Wohnkammer als Steinkern mit Schalenresten; Quebrada Yerbas Buenas; B. St. M. 1978 II
136; a: Lateral-, b: Ventralansicht; nat. Gr.

Peronoceras cf. vortex (SIMPSON, 1855)

Phragmokon mit Kalzit ausgefüllt (Oberfläche nur z. T. erhalten), (] Beginn der Wohn-
kammer); Quebrada Cortaderita; B. St. M. 1978 II 137; nat. Gr.

Wohnkammer Steinkern (] Beginn der Wohnkammer) mit Resten des Phragmokons; Que-
brada Cortaderita; B. St. M. 1978 II 138; nat. Gr.

Zitteliana 6, 1980

Tafel 5

Zitteliana 6, 1980 Tafel 6

Fig. 1:

Big. 2/ayb:

Fig. 3:

Tafel 6

Peronoceras cf. vortex (SIMPSON, 1855); Wohnkammer-Steinkern; Quebrada Paipotito;
B. St. M. 1978 II 143; nat. Gr.

Peronoceras sp. ex gr. P. bolitoense n. sp.; Steinkern-Phragmokon mit Rest der Wohn-
kammer; Quebrada Cortaderita; B. St. M. 1978 11 152; a: Lateral-, b: Sagittalansicht; nat. Gr.

Peronoceras ct. bolitoense n. sp.
Phragmokon mit Schalenresten; Juntas del Toro; B. St. M. 1978 II 155; nat. Gr.

Peronoceras bolıtoense n. sp.

Wohnkammer-Steinkern (die beiden letzten Windungen), Phragmokon mit Schalenresten
und Kalzit ausgefüllt; Quebrada El Bolito; B. St. M. 1978 II 147; nat. Gr.

Holotypus; Phragmokon in Schalenerhaltung (mit Kalzit ausgefüllt), letzter Umgang Wohn-
kammer-Steinkern; Quebrada El Bolito; B. St. M. 1978 II 146; a: Lateral-, b: Frontalansicht;
nat. Gr.

Phragmokon-Innenwindung (vorw. in Schalenerhaltung); Rio Manflas (Profil zum Porte-
zuelo El Padre); B. St. M. 1978 II 151; nat. Gr.

Bie.15,2:

Tafel 7

Peronoceras moerickei n. sp.

Holotypus; Wohnkammer-Steinkern mit Resten des Phragmokons; Quebrada EI Asiento;
B. St. M. 1978 II 161; nat. Gr.

Wohnkammer-Steinkern; Quebrada Yerbas Buenas; B. St. M. 1978 II 169; nat. Gr.

Peronoceras cf. bolitoense n. sp.

Phragmokon (innere Windungen in Schalenerhaltung, letzte als Steinkern), | Beginn der
Wohnkammer (am Ende lateral verdrückt); Quebrada Yerbas Buenas; B. St. M. 1978 II 153;
a: Lateral-, b: Frontalansicht; nat. Gr.

Phragmokon (in Kalziterhaltung) mit Resten der Wohnkammer; Juntas del Toro; B. St. M.
1978 IL 154; nat. Gr.

Zitteliana 6, 1980 Tafel 7

Zitteliana 6, 1980 Tafel 8

Fig. 1a, b:

Fig. 2a, b:

Tafel 8

Peronoceras cf. planiventer (GUEx, 1972)
Phragmokon-Steinkern mit Schalenresten; Quebrada Larga; B. St. M. 1978 II 170; a: Late-
ral-, b: Frontalansicht; nat. Gr.

Peronoceras cf. crassicostatum (GUEX, 1972)
Phragmokon-Steinkern mit Schalenresten; Quebrada Larga; B. St. M. 1978 II 171;a: Lateral-,
b: Frontalansicht; nat. Gr.

Fig. 3, 4, 6-12: Collina chilensis n. sp.

Ventralseite der Wohnkammer (Steinkern mit Schalenresten, } Beginn der
Wohnkammer); Rio Pulido; B. St. M. 1978 II 192; nat. Gr.

Holotypus; Phragmokon (z. T. in Kalzit erhalten und mit Schale), letzter Umgang

Wohnkammer-Steinkern; Quebrada EI Bolito; B. St. M. 1978 II 176; a, c: Lateral-,
b: Ventralansicht; nat. Gr.

Phragmokon z. T. mit Schale, letzter Umgang Wohnkammer-Steinkern; Rio Pulido;
B. St. M. 1978 II 190; nat.Gr.

Phragmokon mit Schalenresten; Rio Pulido; B. St. M. 1978 II 191; nat. Gr.

Phragmokon als Kalzitsteinkern und mit Schale (lateral etwas verdrücke); Quebrada El
Bolito; B. St. M. 1978 II 180; a: Lateral-, b: Sagittalansicht; nat. Gr.

Phragmokon mit Schalenresten, letzter Umgang zumindest z. T. Wohnkammer; Quebra-
da El Bolito; B. St. M. 1978 II 179; nat. Gr.

Wohnkammer-Steinkern, Phragmokon mit Kalzit ausgefüllt (Oberfläche nicht erhalten):
Quebrada El Bolito; B. St. M. 1978 II 177; nat. Gr.

Wohnkammer-Steinkern (] Beginn der Wohnkammer), Quebrada El Corral; B. St. M.
1978 II 201; nat. Gr.

Wohnkammer-Steinkern (] Beginn der Wohnkammer), Phragmokon mit Kalzit ausgefüllt
(Oberfläche nur z. T. erhalten); Quebrada Yerbas Buenas; B. St. M. 1978 II 200; nat. Gr.

Collina sp.

Äußere Windung Wohnkammer-Steinkern (z. T. mit Schale), Phragmokon mit Kalzit
ausgefüllt (z. T. Schalenoberfläche erhalten); Quebrada Larga; B. St. M. 1978 II 209;
nat. Gr.

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TION NOILNLILSNI NVINOSHLINS S31UVUAIT LIBRARIES „SMITHSONIAN INSTITUTION NOILNLILSNI NVINOSHLI
< < = gm 23. < ze <
n ‚& ı #3 3 z Ns
AA N i N !
N 6 r ö DE A =) 2 N 8
N 2, = 2, 7 = = END 2,
° >. = > = N > = N >’
zZ oO > [72) z 72) -; =

YAI7 _ LIBRARIES SMITHSONIAN INSTITUTION NOILNLILSNI_NVINOSHLIWNS S31IUV4YAI1 LIBRARIES

z A: 2 - 2 z

er = JE m, 5 =E a & -

= < #3 < = NN < =

= GG #: eE = c N R X =

= De E 3 0Vo =

[e) = [e) = [e) IN En oO

z =) =. er = en >
JTION NOILNLILSNI NVINOSHLIWS S31UVYUAI1 LIBRARIES SMITHSONIAN INSTITUTION NOILNLILSNI NVINOSHLI
N

INSTITUTION

SMITHSONI

saıyvueln
INSTITUTION
S31yV4811
INSTITUTION
saluvygı
INSTITUTION

Yall LIBRARIES SMITHSONIAN INSTITUTION NOILNLILSNI NVINOSHLINS S3IUVYAI1 LIBRARIES
As NS je

NVINOSHLINS, S31UVY817_ LIBRARIES SMITHSONIAN

NVINOSHLIWNS
NVINOSHLINS
SMITHSONIAN

SMITHSONIAN
RB
NVINOSHLIWNS

h
s31uv4gı7 LIBRARIES

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NOILNLILSNI NVINOSHLIWS

SMITHSONIAN _ INSTITUTION NOILNLILSNI NVINOSHLI

Em | Se ep —=

SMITHSONIAN
Da
7;

S_ SMITHSONIAN

JTION

S
S
S

7) = 2 .o = RS 7) W
3 2.54,» 2 = UN 3 Eye
= WW) — < - IN I < = WE
= > GG & «© S N E E = 77:
2 eo s ee : :@
er N 2 2
TITUTION NOILNLILSNI NVINOSHLINS _S31UVY911 LIBRARIES SMITHSONIAN INSTITUTION NOILNLILSNINVINOS
z Bi z = z E z au
(=) = _ z
= ie) = w = @ = w
E En) & E E EN S En N
> Hm > „> > N
= _ = 2) = EN
m = ar a 4 = > = N
m m nm m eo m 2 m SS
= (0) = o = (7) = [7
YELBI EIBIRAR LES SMITHSONIAN INSTEITLEDUFROLINZLLSNI NVINOSHLIWS S3!UVU8IT LIBRARIES „SMITHS
i < x = z * z z AR < x Z
* = 3 TG, z
ö T ö Q = = GA ° NA =
28 2 8 8 WIEN:
ESS 2 EIS 2, 5 ee Ns 2
N \ =, | \ =
= En 2 7 2 z 3 7 x =

FITUTION NOILNLILSNI_NVINOSHLINS S31IYUVYAII LIBRARIES SMITHSONIAN INSTITUTION NOILNLILSNI_NVINOS

LIBRARIES SMITHSONIAN

= 7) — = (02) >
m 2 wu 3 z wu TR
= 4 73 ä en x = N
a 3 AD E S 5 «= N
= a A 5 ° = 8.
= = = 74 > = <
uUV4yglI1 LIBRARIES SMITHSONIAN INSTITUTION NOILNLILSNI NVINOSHLINS S3IUV4Y81I7 LIBRARIES SMITHS
= m ze =
= S N ° RR: e)
Be) = E ES E Bl
3 Er 2 E E EYGH
= 7 2 5 5 a
m z m z z ie

TITUTION NOILNLILSNI NVINOSHLINS S3IUVWYSITI_LIBRARIES SMITHSONIAN INSTITUTION NOILNLILSNI NVINO:

NVINOSHLINS S31YUVY817
NVINOSHLINS S31IUVY4817

[42] ==
N < E = „Z Ni < N N <
N 53 z 5 ZzıSıD z SQ a
NN FE [e) Sr oO TEN (6) Ni \ 77 [e]
2 = 2 E SS EN ZT:
> = > s= s s $=
2 [77] = [02] 75) [72]

3V4g11 LIBRARIES SMITHSONIAN INSTITUTION NOILNLILSNI s314vug11 LIBRARIES SMITHS

2 (2) = (77) _ =
Z Se w z u z #
= LG 5 = —f BF | Fe Ay
= 2, DD = < = = 3 ER:
e x GE E De E E e x DW
= m = f =. 1 = ) I;
= = 9 - S = 5 a
= en = ROM ET
TITUTION_ NOILNLILSNITNVINOSHLIWS“ S31UWYAII_ LIBRARIES” SMITHSONIAN_ INSTITUTION NOILNLILSNITNVINOS
5 Eu 5 = z E z Eu
° = =) = ö = 5 =
5 ® IN 5 © E ‚z E E N
E SCORE I > E > = re
Fi >] III >) = >.) _ >) EN
57 m NS ‚= = E ee HF = N
_ —_ w = —
YVUSIT LIBRARIES „SMITHSONIAN_ INSTITUTION NOILNLILSNI_ NVINOSHLINS SF1UVYWAIT LIBRARIES SMITH:
I = 3 = & N 2 z < u <
z = = =
ZEN N: > N E = NG:
FE SIDE 2 N 8 Z DNS E
END: ES: 2. E NS 2
S = \ N £
= ES z = en = = 3 x >

FITUTION NOILNLILSNI_NVINOSHLIWNS S3IUVYAIT LIBRARIES SMITHSONIAN INSTITUTION NOILNLILSNI_ NVINOS

LIBRARIES SMITHSONIAN

me = u = z m RN
mm = © = u = ai N
< = De: = ya < Ex
= = > = = = Ser
= 5 = e) ° = 9
= =) zZ z Ss
uUvyglT LIBRARIES SMITHSONIAN INSTITUTION NOILNLILSNI NVINOSHLINS S31IYV481I1I LIBRARIES SMITH:
r z z = z rm z
_ o = oO zn oO = oO
I) = ‘w@ = w = I") =
= 5. 2 5 E) E [2 Be
> E5 > E >. = > EYG.4
a BE 2 = a E = Ei
m z m 2 m 2 m 2,23
[62] —_— _ [07] . = [07] —
TITUIe NOILNLILSNI a !aVUBIT LIBRARIES „SMITHSONIAN INSTITUTION NOJLNILLSNIENMIND:
Sr .< z ne u. 0. 28 .<
N zZ ie iz. SS = z N N = z
S © Ey: (©) SI & SE oO NS‘ z [®)
\ 2 N, = SW 17) WR er) 12)
E 2 E Nr = 2 E
> = > = NR > > > =
[77] zZ [2] .. 2 [77] = [7]

. = 2 r 2
uvugı7 LIBRARIES SMITHSONIAN INSTITUTION NOILNLILSNI NVINOSHLIWS Ss314V/4811 LIBRARIES SMITHS

TTS,

429 0449

ION LIBRARIES

INN!

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