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<* FIELDIANA 
Geology 

Published by Field Museum of Natural History 

Volume 33, No. 12 November 26, 1975 

This volume is dedicated to Dr. Rainer Zangerl 

Ptycholepis marshi Newberry, 

A Chondrostean Fish from the Newark Group 

of Eastern North America 

BOBB SCHAEFFER 

Curator, Department of Vertebrate Paleontology 

American Museum of Natural History 

David H. Dunkle 

Curator of Paleontology 
Cleveland Museum of Natural History 

Nicholas G. McDonald 

Department of Geology 

Wesleyan University 

Middletown, Connecticut 

INTRODUCTION 

In 1878, S. W. Loper, an inveterate collector of fossil fishes in 
the Triassic rocks of the Connecticut Valley, discovered several 
specimens of a new fossil fish at his well-known locality near 
Durham, Connecticut. The specimens were presented to Professor J. 
S. Newberry, who recognized them as a new species of the genus 
Ptycholepis, previously known only from the European Triassic and 
Liassic. Newberry (1878) named this species P. marshi and later 
provided a more complete description of it in his monograph on the 
fishes and plants from the Triassic of New Jersey and the 
Connecticut Valley (Newberry, 1888). 

Although additional specimens were collected at Durham and 
other localities in the Connecticut Valley, subsequent discussions of 
P. marshi (see, for example, Lesley, 1889; Woodward, 1895; 
Eastman, 1905, 1911) added little to the knowledge of the species, in 
part because of poor preservation and inadequate preparation 
techniques. Between 1942 and 1949, two amateur collectors, F. M. 

Library of Congress Catalog Card Number: 75-25181 The Library of the 

Publication 1220 205 



MAY0 7 1976 G£OLC 



206 FIELDIANA: GEOLOGY, VOLUME 33 

Baer and W. H. Martin (1949), found some unusually well-preserved 
examples near Haymarket and Midland, Virginia. Further collection 
at these sites by D. H. Dunkle and S. P. Applegate produced 
additional specimens that are now in the United States National 
Museum of Natural History and the American Museum of Natural 
History. In 1970, W. B. Cornet and N. G. McDonald reopened an 
old Loper site at North Guilford, Connecticut, not far from the 
Durham locality. A number of exceptionally well-preserved exam- 
ples of P. marshi were recovered, along with Semionotus and 
various redfieldiids. 

Most of the specimens used in this study, from Virginia and 
Connecticut, have been prepared by the airbrasive method. 

The authors are indebted to Farish A. Jenkins, Jr., Museum of 
Comparative Zoology, Harvard College; Keith Thomson, Peabody 
Museum of Natural History, Yale University; J. W. Peoples, 
Wesleyan University; and Nicholas Hotton, III, United States 
National Museum of Natural History, for the loan of specimens 
used in this study. They also gratefully acknowledge the helpful 
interpretations of European Ptycholepis species provided by Colin 
Patterson of the British Museum (Natural History), and Sylvie 
Wenz of the Museum National d'Histoire Naturelle, Paris. They 
would like to thank W. B. Cornet for important field data and for 
agreeing to the donation of many P. marshi specimens collected by 
him and N. G. McDonald to the American Museum of Natural 
History. Paul Olsen has kindly provided new locality data on P. 
marshi in New Jersey. 

The photographs were taken by Chester Tarka, and the 
drawings were made by Lorraine Meeker. The specimens used in 
this study were prepared by Walter Sorensen, and preliminary 
editing of the manuscript was done by Marlyn Mangus. 

Abbreviations 
AMNH, American Museum of Natural History 
BM(NH), British Museum (Natural History) 
MCZ, Museum of Comparative Zoology, Havard College 
NMNH, United States National Museum of Natural History 
WU, Wesleyan University 
YPM, Peabody Museum of Natural History, Yale University 



SCHAEFFER ET AL. : PTYCHOLEPIS MARSHI 207 

SYSTEMATICS 

Order Ptycholepiformes Andrews et al., 1967 
Family Ptycholepididae Brough, 1939 
Ptycholepis Agassiz, 1832 
Ptycholepis Agassiz, 1832, p. 142. 

Type species. — Ptycholepis bollensis Agassiz. 

Distribution. — Middle Triassic: Italy; Upper Triassic: Austria; 
Upper Triassic-?Liassic: Virginia, New Jersey, Connecticut; Lower 
Liassic: England; Upper Liassic: Germany, France, England. 

Revised generic diagnosis — Body elegantly to deeply fusiform; 
snout with nasals separated by postrostral bone; paired 
rostropremaxillae in subrostral position, meeting in midline; maxilla 
with slight postorbital expansion in articulation with preopercular; 
nasal and dermosphenotic in contact above orbit; suborbitals 
(known in three species) numerous (8-20), narrow, and overlapping 
anterior border of preopercular; preopercular nearly vertical, 
broadest at contact with maxilla; suspensorium nearly vertical; 
antopercular present; interopercular absent; four to six branchio- 
stegals, uppermost twice as wide as others; coronoid process absent; 
marginal teeth on maxilla and dentary small, uniform and 
acuminate; origin of dorsal fin about midway between snout and 
caudal peduncle; rays of dorsal and anal fins completely segmented; 
rays of paired fins segmented only distally; only dorsal rays not 
bifurcated; caudal fin robust, hemiheterocercal, equilobate and 
moderately cleft; all fins (including both lobes of caudal) with 
fulcra; scales rhomboidal behind shoulder girdle, elsewhere much 
longer than deep, with ganoine arranged in low, longitudinal ridges, 
frequently anastomosing; posterior borders of scales notched. 

Ptycholepis marshi Newberry, 1878 

Type. — AMNH 575, a nearly complete, but poorly preserved, 
fish from the Newark Group at the S. W. Loper locality near 
Durham, Connecticut. 

Distribution. — Upper Triassic-?Liassic Newark Group of 
Massachusetts, Connecticut, New Jersey, and Virginia. 

Specific diagnosis. — Differs from other species of Ptycholepis 
in having combined maximum width of parietals nearly equal to 
length and in having posterolateral corners of parietals extended 
posteriorly. Maxilla expanded postorbitally as in P. barboi; median 



208 FIELDIANA: GEOLOGY, VOLUME 33 

gular extending to posterior border of mandible, lateral gulars 
mostly covered by median gular; six branchiostegals; dermal bone 
ornamentation weak to strong; origin of dorsal fin at fourteenth 
scale row; gradual change from rhomboidal to narrow flank scales 
in first five vertical scale rows. 

Referred specimens. — From the Shuttle Meadow Formation, 
Durham, Connecticut: AMNH 575 (type), AMNH 669, MCZ 6254, 
WU 907, WU 865. From the Shuttle Meadow Formation, North 
Guilford, Connecticut: AMNH 4519, AMNH 4676, AMNH 4677, 
AMNH 4713, AMNH 4714, AMNH 4715, AMNH 4718. From the 
Brunswick Formation, Watchung, New Jersey: YPM 6283. From 
the Brunswick Formation, Boonton, New Jersey: YPM 6272. From 
the ?Bull Run Shale, Midland, Virginia: AMNH 4808, AMNH 4810, 
AMNH 4811, AMNH 4812, AMNH 4813, AMNH 4814, AMNH 
4815, AMNH 4816, AMNH 4817, USNM 21288, USNM 21289, 
USNM 21290, USMN 21840. From the ?Bull Run Shale, Hay- 
market, Virginia: USNM 18323. The specimens listed above were 
the most useful in this study because of their well-preserved 
morphological details. In addition, there are several dozen cata- 
logued and uncatalogued specimens of P. marshi at various 
institutions. 

Description. — Approximate measurements of the more 
complete specimens of P. marshi on which this description is based 
are presented in Table 1. The specimen sample includes fishes of 
relatively modest size and slender body (figs. 1, 2). An average of 28 
per cent of the standard length is occupied by the head and 
opercular apparatus. It is not possible to obtain an accurate 
measurement of the maximum body depth (which occurs in front of 
the dorsal fin), but it is estimated to be less than the length of the 
head, including the opercular apparatus. The dorsal fin is triangular 
and originates near the middle of the body. The anal fin is slightly 
smaller in size, is similarly triangular, and is situated about halfway 
between the pelvics and the caudal. The pelvic fins arise behind the 
termination of the dorsal and are much closer to the anal than to 
the pectorals. The hemiheterocercal caudal fin, supported by a 
stout caudal peduncle (AMNH 4813) is robust, equilobate, and 
moderately cleft. 

The endocranium, seen in NMNH 21289 (fig. 3B), is dorsoven- 
trally compressed and difficult to interpret. It is typically 
palaeonisciform and shows no evidence of subdivision into separate 
centers of ossification. The ethmoid region is about twice as broad 



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SCHAEFFER ET AL.: PTYCHOLEPIS MARSHI 213 

as long, and its ventral surface is marked by numerous pits and 
foramina that indicate nerve and vascular plexi ventral to the nasal 
capsules. The lateral occipital fissure enters the vestibular fonta- 
nelle on either side. The ventral otic fissures extend anteriorly and 
somewhat medially beyond the fontanelles, but whether they have 
a ventromedial junction cannot be determined in this specimen. 
The lateral occipital fissure extends dorsally and laterally to the 
margins of the braincase as preserved. This fissure has not been 
identified dorsally, and the presence or absence of a dorsal posterior 
fontanelle cannot be determined. Neither can the presence of a 
dorsal anterior fontanelle or the size and characteristics of the fossa 
bridgei be demonstrated. 

The dorsal aorta was enclosed in a canal in the cranial floor. A 
single median anterior opening and a single median posterior 
opening are present for the aorta. Openings for the second efferent 
branchial arteries are situated about equidistance between the 
openings for the aorta. The vagus nerve, as usual, emerged through 
the lateral occipital fissure, posterodorsal to the vestibular 
fontanelle. A faint groove traverses the wall of the endocranium in 
a dorsal direction, slightly anterior to the vagal opening. It is 
thought to have accommodated the supratemporal ramus of the 
glossopharyngeal nerve. Anteroventrally the groove is aligned with 
the rostrocaudal jugular depression and the jugular canal. The 
hyomandibular facet is located on the posteroventral surface of the 
postorbital process. 

The dermal skull (figs. 4, 5, 6) is long and narrow and has a 
pronounced rostrum. The suprascapulars are characteristically 
lobate. They are not in contact with one another in the mid-dorsal 
line: body scales may fill the intervening space. The extrascapulars, 
four in number, are quadrangular and are of approximately equal 
dimensions. The parietals are rectangular and about half as wide as 
long. The frontals are twice as long as the parietals and are rather 
irregular in outline. They increase in width from the posterior 
border to the point where they are in lateral contact with the 

Opposite.— 

Fig. 3. Ptycholepis marshi Newberry. Dissociated skull bones. A, AMNH 4817. 
B, NMNH 21289. Both xl.6. Abbreviations: dent, dentary; dpt, dermopterotic; dptq, 
dermal bones of palatoquadrate; fr, frontal; hym, hyomandibular; io, infraorbital; 
mx, maxilla; neu, neurocranium; pa, parietal; pop, preopercular; pros, postrostral; 
ptq, palatoquadrate; sbo, suborbital. 




ropmx 



214 



SCHAEFFER ET AL.: PTYCHOLEPIS MARSHI 215 

anteromesial edge of the dermopterotic and with the posteromesial 
border of the dermosphenotic. The borders of the frontals are 
emarginated anteromesially to receive the postrostral; anterolat- 
eral^ they are truncated for the nasals. The heavily ornamented 
postrostral is a robust bone with a relatively long and narrow 
posterior portion and a somewhat shorter, broader, and rounded 
anteroventral part. The flanking nasal elements are massive. 
Indentations in the lateral margin of the postrostral and in the 
anterior and posterior borders of the nasal bones mark the positions 
of the anterior and posterior nasal openings. The long crescent- 
shaped dermosphenotic is broader posteriorly than anteriorly, where 
it is in narrow contact with the nasal. The dermopterotic is in 
anteromesial contact with the frontal. It is somewhat longer than 
the parietal and is wider anteriorly than posteriorly. 

The ovate orbit is about one-third of the total length of the 
skull. The mouth is barely subterminal. The mandibular symphysis 
is long and the suspensorium is nearly vertical. The ventral and 
posterior border of the orbit is formed by four narrow infraorbitals. 
The supraorbital bone has a long anteriorly-directed process that 
partly excludes the dermosphenotic from the orbital margin. The 
anterior infraorbitals articulate anteriorly with paired elements 
that are in the same position as the so-called rostro-antorbito- 
premaxillae (figs. 4B, 5) of Boreosomus Stensio, 1921 (see Nielsen, 
1942, fig. 71). These elements meet in the midline below and behind 
the nasals and the postrostral, and they carry several sensory canal 
pores. Although they form the anterior upper border of the mouth, 
there is no evidence that they bear teeth. Between the infraorbitals 
and the preopercular there is a vertical series of narrow bar-like 
suborbital bones that vary in number from 7 to 13. The fixed 
maxilla has a lobate postorbital expansion. The oral border of the 
maxilla is gently curved; it bears a weak internal flange to receive 
the palatoquadrate. The mandible is a slender element with a 



Opposite.— 

Fig. 4. Ptycholepis marshi Newberry. Reconstruction of skull. A, Dorsal aspect. 
B, Ventral aspect. C, Lateral aspect. Abbreviations: aop, antopercular; br, 
branchiostegal; dent, dentary; dpt, dermopterotic; dsph, dermosphenotic; esc, 
extrascapular; fr, frontal; io, infraorbital; lg, lateral gular; mg, median gular; mx, 
maxilla; na, nasal; op, opercular; pa, parietal; pop, preopercular; pros, postrostral; 
ropmx, rostro-antorbito-premaxilla; sbo, suborbital; so, supraorbital; sop, subopercu- 
lar. 




Fig. 5. Ptycholepis marshi Newberry. Skulls in lateral aspect showing variation 
in dermal bone ornamentation. A, AMNH 4676, X2.2.B, AMNH 4718, X2.1. 



216 




Fig. 5 (continued). Ptycholepis marshi Newberry. Skulls in lateral aspect 
showing variation in dermal bone ornamentation. C, AMNH 4715, X2.0.D, AMNH 
4714, X2.3. 



217 



218 FIELDIANA: GEOLOGY, VOLUME 33 

straight oral border and a long symphysis. The maxilla and 
mandible have a single row of tiny, uniformly -spaced villiform 
teeth. The palatoquadrate and the hyomandibular resemble their 
counterparts in the European species of Ptycholepis (Brough, 1939; 
Wenz, 1967). 

The preoperculum is exposed in several specimens. It extends 
from the margin of the dermopterotic to the posteroventral 
extremity of the maxilla. Its posterior border is gently convex 
against the anteriorly concave margins of the antoperculum, 
operculum, and suboperculum. The anterior border is covered by 
the overlapping suborbitals above and by the posterodorsal border 
of the maxilla below. Between the two overlap areas the 
preoperculum is produced into a sharp, forwardly-directed spur. A 
perusal of the palaeonisciform restorations assembled in Schaeffer 
(1973) shows that this preopercular shape is frequently associated 
with a nearly vertical suspensorium. 

The operculum is slightly deeper than long; it is somewhat 
closer in size to the suboperculum than it is in P. bollensis, P. curta, 
or P. barboi. 

A large median gular extends from the mandibular symphysis 
almost to the transverse level of the angular. The lateral gulars are 
mostly covered by the median gular. There are six paired 
branchiostegal rays; the uppermost one is enlarged to nearly half 
the size of the suboperculum. 

Ornamentation of the skull bones (figs, 5, 6) consists generally 
of wide enameled ridges with narrow interspaced grooves. For the 
most part they are rostrocaudally directed. Density of ornamenta- 
tion varies from total coarse coverage near centers of ossification to 
wide peripheral bare areas. Invariably the ornamentation is coarsest 
rostrally, progressively less pronounced posteromesially and 
posterolateral^, and weakest ventrolaterally and ventrally. 

Determination of the lateral line sensory system of the skull is 
dependent on the degree of ornamentation. In some specimens the 
course of the supraorbital canal through the nasals and frontals is 
indefinable; in others it may be marked by ganoine ridges higher 
than, but parallel to, the ornamental ridges, or by discrete pores. 
The three pairs of pit lines in the parietals are similarly variably 
observable. In some specimens they are well defined, but in others 
they may be only partially developed on one side and absent on the 
other. In one specimen (AMNH 4812) where the internal face of the 




Fig. 6. Ptycholepis marshi Newberry. Skulls in dorsal and ventral aspect showing 
variation in dermal bone ornamentation. A, AMNH 4677, dorsal aspect, X2.1. B, 
AMNH 4813, dorsal aspect, X3.0.C, AMNH 4812, dorsal aspect, X3.4.D, AMNH 
4811, ventral aspect, X2.5. 



219 



220 FIELDIANA: GEOLOGY, VOLUME 33 

rostroantorbito-premaxilla is exposed, the ethmoidal sensory 
commissure can be seen. The preopercular sensory canal internally 
parallels the posterior margin of the preopercular bone, but emerges 
externally on the median vertical axis. The entire sensory canal 
pattern is palaeonisciform. 

Scales (fig. 7B) with ganoine-covered ridges are found over the 
entire body. They are distinctive in their length-to-height 
proportions and ornamentation. They agree in all observable details 
with the scales of P. bollensis (Aldinger, 1937). Approximately 50 
vertical scale rows (fig. 2) occur between the shoulder girdle and the 
caudal inversion. The first two rows have equilateral rhomboidal 
scales that are elaborately ornamented with both anteroposterior 
and oblique striae. Posteriorly the scales are four times as long as 
high. Anteriorly each vertical row includes about 50 scales, but the 
number diminishes to about 39 in the region of the anal fin. 

The dermal elements of the shoulder girdle are incompletely 
known, but they seem to resemble those of P. bollensis (Wenz, 
1967). The pectoral fin (fig. 2) consists of about 18 principal rays. 
The first of these is very robust, but it is only half as long as the 
longest ray. The second and third rays are acuminate and jointed, 
but unbifurcated. The fourth ray is the longest. It branches distally, 
as do all the succeeding rays. The first four rays are fringed by a 
double row of fulcral scales. 

The pelvic fins are smaller than the pectorals. They originate 
below the fourteenth vertical scale row, and each consists of from 
13 to 16 principal rays. They are fringed anteriorly by a double row 
of fulcra. The anterior four rays are acuminate and jointed, but not 
dichotomized, as are the remainder of the rays. The dorsal fin arises 
above the thirteenth vertical scale row. It consists of from 20 to 24 
principal rays, of which approximately the first five are nonbranch- 
ing and fringed by a double row of fulcra; the remaining rays are 
articulated and distally dichotomous. The anal fin is smaller than 
the dorsal. It originates beneath the twenty-fifth vertical scale row, 
behind the pectoral girdle. It consists of about 14 principal rays. 
The anterior four are acuminate and articulated; the remainder are 
bifurcated distally. This fin probably also possesses a double row of 
fulcra. 

The caudal fin is equilobate (fig. 7A). The epichordal lobe 
consists of about 20 principal rays, all regularly articulated and 
distally dichotomous. The hypochordal lobe is composed of about 30 




Fig. 7. Ptycholepis marshi Newberry. A, AMNH 4813, base of caudal fin, X4.0. 
B, AMNH 4715, flank scales, X2.0. 



221 



222 FIELDIANA: GEOLOGY, VOLUME 33 

principal rays. The anteroventral rays are acuminate and jointed, 
but not dichotomized. The borders of both the epichordal and 
hypochordal lobe are fringed by a double row of fulcral scales. 

Discussion. — Before considering the relationships of P. marshi, 
it will be helpful to reconsider the affinities of the genus Ptycholepis 
in terms of its presumed shared derived characters, and to discuss 
the status of the seven other currently recognized species in terms 
of both shared and unique derived characters. 

On the basis of "characters-shared-in-common," Aldinger (1937) 
and Brough (1939) independently concluded that Ptycholepis is 
related to the palaeonisciform genus Boreosomus, and, in fact, that 
the latter is ancestral to the former. Following a detailed re- 
examination of P. bollensis, Wenz (1959, 1967) listed the following 
characters shared by Boreosomus and Ptycholepis: (1) completely 
ossified neurocranium of palaeonisciform type; (2) dermal bone 
pattern of cranial roof; (3) rostral (snout) pattern; (4) large orbit; 
(5) numerous suborbitals; (6) antopercular (dermohyal) present; (7) 
preopercular (sometimes) divided horizontally into two separate 
components; (8) mandible elongated, extending to front of snout, 
with mandibular canal clearly curved anteriorly; (9) hyomandibular 
with large opercular process and without a canal for the 
hyomandibular branch of the facial nerve; (10) palatoquadrate of 
the palaeonisciform type; (11) cranial dermal bones and scales 
strongly ornamented. 

Wenz went on to list other Ptycholepis characters not shared 
with Boreosomus: (12) hyomandibular facet on braincase horizon- 
tal; (13) vertical preopercular with preopercular canal along 
anterior border; dorsal part occasionally covered by suborbital 
bones extending to anterior border of antopercular; (14) maxilla 
with no (or slight) postorbital expansion; (15) wide proximal 
hypurals; (16) hemiheterocercal tail; (17) fin rays equal in number 
to basals, small in number, robust and bifurcated distally. 

Many of the resemblances and differences between Boreosomus 
and Ptycholepis that Wenz noted had previously been discussed by 
Aldinger (1937) and Brough (1939), who made additional comments 
on the opercular series, the fins, and scales. 

It is now important to decide which character states previously 
considered to relate Boreosomus and Ptycholepis are primitive 
palaeonisciform ones. We regard the resemblances listed under (1), 
(2), (3), (4), (6), (8), (10), and perhaps (9) as primitive shared 



SCHAEFFER ET AL.: PTYCHOLEPIS MARSHI 223 

character states that are of no value in postulating relationships. Of 
the characters that Ptycholepis does not share with Boreosomus, 
(12), (13), and (14) are involved in the nearly vertical suspenso- 
rium— a condition that certainly evolved numerous times indepen- 
dently among the early chondrosteans. The other unshared 
characters, (15), (16), and (17), are characteristic of several 
presumably unrelated subholostean groups. 

The suborbital series has been described for three of the eight 
species of Ptycholepis. P. marshi has 7 to 13 of these elements. 
Although Brough (1939) figured four suborbitals for P. curta 
Egerton (from the Lower Lias of Dorsetshire), one specimen 
(BMNH 39493) actually has about 20 {fide Sylvie Wenz and C. 
Patterson). The type species of Ptycholepis, P. bollensis (from the 
Upper Lias of Bavaria, Yorkshire, and Yonne), has 7 to 13 
suborbitals, according to Wenz (1967), rather than two, as 
illustrated by Gardiner (1960). It seems probable, however, that the 
primitive suborbital number for the palaeonisciforms was about two 
(Schaeffer, 1973). The high number in Boreosomus, P. marshi, P. 
curta, and P. bollensis may therefore be regarded as a derived 
condition. Unfortunately, the cheek elements are unknown in the 
other species of Ptycholepis. 

The large opercular process on the hyomandibular noted by 
Wenz (1967) for P. bollensis and Boreosomus is also present in P. 
barboi Bassani (1939) and P. marshi. A robust opercular process is 
perhaps a derived condition, but our knowledge of the 
palaeonisciform hyomandibular is too incomplete to propose that 
such a process is shared by only these two genera. 

The type of dermal bone ornamentation characteristic of 
Ptycholepis is also known in Boreosomus (Nielsen, 1949) and in 
various other palaeonisciforms, such as Moythomasia Gross (Jessen, 
1968). It probably has little diagnostic significance except at low 
taxonomic levels where details of the ornamentation pattern may 
be derived and unique. Most specimens of P. marshi from Virginia 
and Connecticut have the typical heavy ribbing on all the dermal 
elements except the gulars. However, about 10 per cent of the 
specimens from both areas have very sparse sculpturing over the 
entire dermal skull. Because of this distinctive difference in 
ornamentation, we have considered the desirability of recognizing 
two species from the Newark Group. However, there is at least one 
specimen (AMNH 4812) from Midland, Virginia, that shows a more 
or less intermediate condition between heavy and sparse ornamen- 



224 FIELDIANA: GEOLOGY, VOLUME 33 

tation. Ornamentation expression is definitely not growth related, 
and because of the high frequency of strong ribbing, there is no 
basis for assuming that the differences represent sexual dimorphism. 
A reasonable explanation is that the Newark Group has a single 
species of Ptycholepis and that the more or less discontinuous 
expression of the ornamentation is an example of polymorphism 
(sensu Mayr, 1963) that is skewed, for some reason, toward greatest 
ornamentation density. 

The characteristic narrow flank scales of Ptycholepis always 
have two to four wide, ganoine-covered ridges separated by much 
narrower grooves. The ridges usually anastomose near the free edge 
of the scale, which tends to be notched (denticulated). Boreosomus 
has much deeper scales with more numerous and more delicate 
oblique ganoine ridges. The free edge of the scale is also 
denticulated. In cross-section the ridges of both Ptycholepis and 
Boreosomus are seen to be composed of successive layers (gener- 
ations) of enameloid separated by elevations of dentin that rise 
above the common dentin layer and form the floor of the grooves 
(see Aldinger, 1937, figs. 87, 88, 89). This histological pattern also 
occurs in other palaeonisciforms with similar scale ornamentation, 
e.g., Acrolepis Agassiz, Acropholis Aldinger, Plegmolepis Aldinger, 
and Boreolepis Aldinger. Apparent differences and resemblances in 
other aspects of the scale fine structure, such as the dentine canals, 
are difficult to assess. If we assume that the primitive state was one 
in which the enameloid and dentine layers were more or less 
continuous in cross section, with the horizontal and vertical canals 
arranged in irregular fashion, then the regular arrangement of these 
canals in Ptycholepis may be regarded as a derived condition. 
Although the scale architecture of Boreosomus resembles that of 
Ptycholepis, the resemblance is not exclusive. 

Unequivocal, unique derived character states for Ptycholepis 
are few. In regard to the dermal skull pattern, the absence of a 
median rostral, the relatively long frontals and dermosphenotics, 
and the modifications in the cheek related to the vertical 
suspensorium are by no means unique to Ptycholepis and 
presumably evolved several times independently in other 
palaeonisciform groups. The numerous narrow bar-like suborbitals 
in P. marshi, P. bollensis, and P. curta may represent a unique 
derived condition for the genus. The suborbitals are narrower, more 
elongate, and more numerous in these species than in Boreosomus. 
The ornamentation of the dermal bones, when strong, as in P. 



SCHAEFFER ET AL.: PTYCHOLEPIS MARSHI 225 

bollensis, P. curta, and most specimens of P. marshi, is a useful, but 
inconstant, recognition character that, again, is not unique to this 
genus. 

The squamation is perhaps the most distinctive feature of 
Ptycholepis. The shape of the individual scales, their digitate 
posterior borders, and their few strong ganoine-covered anteropos- 
terior ridges constitute, in our opinion, a unique derived character 
state (see Aldinger, 1937, fig. 85). The enlarged dorsal branchiosteg- 
al also fits into this category. 

The systematic treatment of Ptycholepis obviously poses 
problems that cannot readily be resolved. We have emphasized the 
taxonomic isolation of this genus (which Andrews et al., 1967 
implied in their recognition of the order Ptycholepiformes) by 
noting that many of the character states that Ptycholepis shares 
with other palaeonisciforms are primitive palaeonisciform ones, 
while others may be due to parallelism (e.g., those related to the 
vertical suspensorium ). The alternate hypothesis, which seems less 
parsimonius, would favor regarding Ptycholepis and Boreosomus as 
sister taxa. 

The relationships of P. marshi to the other species of 
Ptycholepis are difficult to ascertain on the basis of available 
information. Unique or shared derived character states for each of 
the recognized species are rarely evident from the published 
descriptions, and a revision of the entire genus is obviously 
necessary. The problems involved are familiar ones to anybody 
using the cladistic strategy for hypothesizing relationships within a 
group of extinct fishes. 

A brief review of the species can begin with P. barboi Bassani 
(Ladinian of the south Tessin). The "distinctive" characters of this 
incompletely known species listed by Brough (1939, pp. 65-66) are 
either primitive palaeonisciform ones or are common to most or all 
species in the genus. We have found no unique derived character 
states to distinguish this species from the others. P. avus Kner 
(Carnian, Austria) remains essentially undescribed in spite of some 
comments by Woodward (1895, pp. 323-324). P. minor Egerton 
(Lower Lias, Leicestershire) is described by Woodward (1895, p. 323) 
as having feeble ornamentation on the dermal skull, but the species 
is not otherwise distinguished. P. monilifer Woodward (Lower Lias, 
Dorsetshire) is discussed in some detail by Woodward (1895, pp. 
322-323), and later by Gardiner (1960, pp. 261-264), but aside from 



226 FIELDIANA: GEOLOGY, VOLUME 33 

being designated as the "largest known species," there are no 
discernible unique derived features. P. curta Egerton (Lower Lias, 
Dorsetshire), as redescribed by Brough (1939) and supplemented by 
some observations of Wenz (1967) and Patterson (pers. comm.) may 
have several unique conditions, including relatively small parietals 
along with elongate and posteriorly acuminate dermopterotics. A 
specimen (BMNH 39493) in the British Museum (Natural History) 
has about 20 narrow suborbitals that overlap only the anterior 
border of the preopercular. Accordingly, Brough's (1939) illustra- 
tions of this specimen should be revised so that the cheek area 
resembles that of P. bollensis (Wenz, 1967). P. gracilis Davis 
(Lower Lias, Dorsetshire) remains practically indeterminate in spite 
of Woodward's (1895, p. 320) comment that the scales differ from 
the anterior overlapped border." P. bollensis Agassiz (Lower Lias, 
Yonne), the type species, has been redescribed and figured by Wenz 
(1959, 1967). Again, there is the problem of recognizing unique 
derived character states. Possibly the extreme reduction of the body 
axis in the caudal fin may be restricted to this species. 

The distribution of Ptycholepis during the Middle and Late 
Triassic and the Liassic can be readily understood in terms of the 
Tethys Sea and the continental seaways in existence before drift 
was initiated. Ptycholepis was a marine form that, for some reason, 
got into several of the Newark basins rather late in their history. 

GEOLOGIC OCCURRENCE 

The Newark Group of eastern North America is a gently folded 
and highly faulted sequence of continental and perhaps transitional 
marine sedimentary rocks, sheets of basaltic lava and diabase 
intrusives of Late Triassic and possibly Early Jurassic age. The 
rocks occur in a series of separate basins extending from Nova 
Scotia to South Carolina. Fossil fishes have been found in most of 
the basins, but they are particularly abundant in the Connecticut 
Valley and from New Jersey to Virginia. 

In apparent contrast to the abundance and widespread 
occurrence of semionotids and redfieldiids in the Newark, P. marshi 
is numerically limited and stratigraphically restricted. Initially 
described by Newberry (1878, 1888) and Loper (1891) from two 
localities in the Connecticut Valley, P. marshi was not recorded 
elsewhere until recent decades. At present P. marshi is known from 
three widely-separated regions: the Connecticut Valley, the 



SCHAEFFER ET AL.: PTYCHOLEPIS MARSHI 227 

Northern part of the New Jersey basin, and the Midland, Virginia, 
area. 

Throughout most of the Connecticut Valley the Newark Group 
is composed of several distinct stratigraphic units: (1) a basal 
sequence dominated by red and gray arkose and conglomerate, with 
minor beds of siltstone and shale (New Haven Arkose); (2) a middle 
series of three basaltic lava formations separated by red and gray 
siltstone, shale, and coarse clastic rocks (Shuttle Meadow and East 
Berlin formations); and (3) an upper unit composed of coarse clastic 
rocks and varying amounts of red and gray shale (Portland Arkose). 
With a few exceptions fossil fishes in the Connecticut Valley are 
confined to thin layers of dark gray to black shale and limestone in 
the Shuttle Meadow and East Berlin formations. The absence of 
fishes in the red beds probably reflects inadequate conditions for 
preservation. The fossiliferous exposures may represent parts of one 
or two widespread black shale layers repeated by faulting, or they 
may be separate and distinct local horizons. Studies by Davis and 
Loper (1891) and recently by Byrnes (pers. comm.) have indicated 
that some black shale horizons do occur at approximately the same 
stratigraphic position and are, in fact, repeated by faulting. Other 
black shales, however, are unique to certain sections and cannot be 
traced or found in equivalent stratigraphic sections. 

Although numerous exposures of fossiliferous strata occur in 
Connecticut and Massachusetts, P. marshi has been recorded from 
only three localities— all in the lower portions of the Shuttle 
Meadow Formation. At two of these, the Durham and Bluff Head 
sites (both south of the town of Durham, Connecticut), equivalent 
units of black shale and limestone are exposed in stream beds. 
Historically, the Durham locality is the most famous fossil fish 
locality in the Connecticut Valley and was extensively worked by 
Davis and Loper (1891), Eastman (1911), and others during the last 
century. Hundreds of plant remains, redfieldiids, semionotids, and a 
few examples of P. marshi and Diplurus were obtained in the years 
of intensive collecting. The fossiliferous limy black shale sequence 
at Durham is approximately 2 ft. thick and outcrops along with 
largely unfossiliferous thin limestone and micaceous gray shale. 
Stratigraphically the shale occurs at an estimated 200 ft. above the 
lava of the Talcott Formation. The rock is extremely black, dense, 
and hard, and it contains appreciable amounts of carbonate. It is 
well laminated and extremely brittle; it can be split easily into 
plates one-quarter to one-half inch thick. The Durham fishes are 



228 FIELDIANA: GEOLOGY, VOLUME 33 

usually well preserved, but it is often difficult to extract them in 
one piece. The beds at Durham are now largely covered over or 
have been removed, but there are large scrap piles of black shale in 
the immediate area. 

Less than a mile northeast of the Durham locality, the 
fossiliferous black shale of the Shuttle Meadow is again exposed in a 
shallow stream bed. This site was discovered by Loper (1891) and 
was given the name "Bluff Head"; but for reasons unknown the 
locality remained unworked until recent years. The shale layers at 
Bluff Head are variably weathered— some parts crumble at a touch, 
others are hard and dense, like the Durham beds. The unweathered 
shale is dark gray to black and is very platy. The upper part of the 
exposure is composed of highly organic micaceous shale with 
occasional lenses of clay; the lower part is characterized by 
rhythmically bedded limy, carbonaceous shale. The entire unit is 
approximately 3 ft. thick and grades into a buff-brown, medium- 
grained quartz sandstone above. It is underlain by a light brown to 
white kaolinite bed. The remainder of the formation consists mainly 
of red siltstone and shale. The weathered shale at Bluff Head 
permits the removal of complete fishes. There is an extremely high 
concentration of fishes at this locality, and the majority are well 
preserved. Some 30 specimens of P. marshi have been recovered to 
date, along with well over 2,000 redfieldiids and semionotids and a 
single specimen of Diplurus cf. longicaudatus. 

Recently a small number of P. marshi remains was obtained 
from a relatively fresh road cut on the northeast corner of Mt. 
Tom, near North Hampden, Massachusetts. A thick stratigraphic 
section of the Holyoke and presumed Shuttle Meadow formations is 
exposed. 1 P. marshi fragments, as well as more numerous 
semionotid and redfieldiid remains, were recovered from a well- 
bedded, 2 ft. thick layer of gray-black calcareous siltstone, roughly 
300 ft. below the base of the Holyoke Basalt. Much of the rest of 
the Shuttle Meadow Formation in this exposure consists of coarse 
red conglomerate and finer-grained redbeds. 

The fishes from Mt. Tom frequently occur in small calcareous 
nodules and are generally dissociated. The rock is very brittle and 
dense, but the specimens are usually well preserved. The specimens 
of P. marshi from this locality are the first and only examples 

'The Talcott Basalt is absent in this area. The sedimentary beds at Mt. Tom are 
presumably equivalent to the Shuttle Meadow Formation. 



SCHAEFFER ET AL. : PTYCHOLEPIS MARSHI 229 

found in the northern two-thirds of the Connecticut Valley, and the 
only ones collected from the Massachusetts Newark. 

Until a few years ago there were no recorded discoveries of P. 
marshi from the New Jersey basin, despite the high concentration 
and widespread occurrence of other fishes (particularly semionotids 
and redfieldiids). Nevertheless, recent field work has resulted in the 
discovery of P. marshi in three north-central New Jersey localities. 
These three localities all occur in the middle and upper portions of 
the Brunswick Formation, stratigraphically the youngest formation 
in the New Jersey basin. However, P. marshi is rare in New Jersey: 
the total number of specimens recovered is fewer than ten, and 
identification of most specimens is based on isolated scales or skull 
bones. A single complete specimen from Boonton, New Jersey, was 
recently found in the collection at Peabody Museum, Yale 
University (Schaeffer, 1952, indicated that the Boonton fishes occur 
in a black shale bed near the top of the Brunswick). The shale at 
Boonton has also yielded vast numbers of other fishes, notably 
semionotids. The two remaining New Jersey localities are in the 
thin dark shale sequences underlying the Second Watchung Basalt 
near the towns of Watchung and Martinsville (Olsen, pers. comm.). 
Here P. marshi is represented only by small patches of isolated 
scales and bones. None has yet been recorded from the sedimentary 
sections below the First Watchung Basalt. 

Applegate (1956) noted that fishes have been found at several 
Newark localities in the Culpepper, Richmond, Farmville, and 
Danville basins of Virginia. Despite the common occurrence of fossil 
fishes, P. marshi has been recovered only from the Culpepper basin, 
near the towns of Midland (Fauquier County) and 
Haymarket (Prince William County). The fishes at Midland occur 
in a 2-ft. thick bed of dark gray, well-laminated silty shale and 
associated carbonaceous limestone that is part of a thick sequence 
of red and brown sandstone. At Haymarket the fossiliferous beds 
are a light buff, soft siltstone. Both sections are presumably in the 
lower portion of the Bull Run Shale (Baer and Martin, 1949). 

If one views the overall distribution of P. marshi in the Newark 
basins, three significant facts emerge: (1) P. marshi is usually a 
minor constituent of the total fish fauna (the only possible 
exception is the Midland assemblage); (2) it occurs locally and 
irregularly in geographically separated regions; and (3) it appears to 
be restricted to certain stratigraphic horizons (the lower Shuttle 
Meadow Formation in the Connecticut Valley, the middle and 



230 FIELDIANA: GEOLOGY, VOLUME 33 

upper Brunswick Formation in New Jersey, and the lower Bull Run 
Shale in Virginia). 

Since all of the European species of Ptycholepis are known only 
from marine deposits, it is suggested that P. marshi did not inhabit 
an exclusively fresh-water habitat. It is possible that it was 
euryhaline, and, as Schaeffer (1967) suggested, entered the Newark 
lowlands from the sea. Although P. marshi is geographically and 
stratigraphically restricted in the Newark basins, it occurs in 
sufficient concentrations at Midland, Durham, and Bluff Head to 
effectively rule out random introduction. 

There is little doubt that many Newark sequences are 
terrestrial in origin, but perhaps others were transitional or even 
coastal marine. Byrnes (1974) and Byrnes and Home (1974), in a 
detailed study of the Connecticut Valley Newark lithology and 
sedimentology, concluded that the rocks reflect several depositional 
environments, including alluvial fan, fluvial, deltaic, and tidal flat. 
It is reasonable to assume that marine fishes could have inhabited 
some of these environments, as could have certain fresh-water 
forms. The problem of the Newark environment cannot be solved 
by the occurence of P. marshi, but the fact that no other species of 
Ptycholepis is known from fresh-water deposits must somehow be 
taken into account. 

The correlation of rock sequences in the different Newark 
basins is difficult, as is the geochronology of the group as a whole, 
because of the absences of both invertebrate and vertebrate index 
fossils and because of the recurrence of lava flows, 1 fossiliferous 
dark shale units, red beds and conglomerates in geographically 
separated basins. Despite these obstacles, most investigators have 
assumed the entire Newark Group to be Upper Triassic (Carnian- 
Norian) in age (see Andrews et al., 1967). This assumption may 
prove to be not totally accurate, as evidenced by recent 
paleobotanical and palynological studies by Cornet et al. (1973). 
These authors concluded that the time-stratigraphic range of the 
Newark Group is greater than previously believed. In a preliminary 
comparison of newly-discovered Newark palynoflorules with those 

•Sanders (1963), in field studies of the Talcott Formation, and de Boer (1968), 
through paleomagnetic studies, have convincingly demonstrated that the lava 
complexes in New Jersey and in the Connecticut Valley are not stratigraphic 
equivalents in the manner proposed by Russell (1878) and other workers. The flows 
do, however, seem to represent a relatively limited period of vulcanism in Newark 
history. 



SCHAEFFER ET AL. : PTYCHOLEPIS MARSHI 231 

from classic European Triassic and Jurassic type sections, they 
propose an upper Carnian-Norian age for the Cumnock Formation 
(North Carolina), the Vinita Beds (Virginia), and the upper part of 
the New Oxford Formation (Pennsylvania); a Carnian-basal Liassic 
age for the Brunswick Formation (New Jersey); a basal Liassic age 
for the Shuttle Meadow Formation (Connecticut Valley) and the 
Midland, Virginia beds; and a Liassic age for the Portland 
Formation (Connecticut Valley). 

If it can be demonstrated that the upper Brunswick Formation, 
the Shuttle Meadow Formation, and the Midland beds (the only P. 
marshi-bearing deposits in the Newark Group) are contempo- 
raneous, or nearly so, a single period of marine deposition in the 
Early Liassic could explain the distribution of P. marshi. 

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