UN1 RSITY OF
ILLIj^iS LIBRARY

NATURAL HIST. SURVEY

FIELDIANA • GEOLOGY

Published by
CHICAGO NATURAL HISTORY MUSEUM

Volume 10 August 28, 1951 No. 11

FAUNA OF UPPER VALE AND CHOZA: 1-5

Everett Claire Olson

Research Associate, Division of Paleontology
Associate Professor of Vertebrate Paleontology, University of Chicago

INTRODUCTION

A study of the vertebrates of the upper part of the Vale Forma-
tion in Knox County and the Choza of Knox and Foard Counties,
Texas, has been in progress since 1946 (Olson, 1948). Intensive
work for several field seasons has resulted in the accumulation of
a large collection of vertebrates, comprising fresh-water fishes,
amphibians and reptiles. The complete preparation and study
of these materials will occupy a period of several years and it is
expected that, in the meantime, additional specimens will be ob-
tained. In view of these circumstances it seems advisable to publish
accounts of specimens as their preparation and study have been
completed, in order that the information may be generally available.
This will be done through a series of articles.

The course of such a program is determined primarily by the
order in which materials are prepared and consequently is non-
systematic in its organization. Once completed, however, the
series will contain information on all the groups of vertebrates that
have been discovered in the formation. A final paper of the series
will be a comprehensive survey of the geology and fauna of the
beds involved, to bring together under a single cover a co-ordinated
study of the various contributions made in the earlier articles.

1. A NEW FAMILY OF THE PARAREPTILIA

The specimen that forms the principal basis for the following
description was preserved in a nodule that had weathered from a
conglomeratic deposit of channel origin. When found, the nodule
had suffered considerable spalling, with the result that little of the
surface bone of the skull was preserved. The skull was also some-
what crushed and the lower jaws had been forced laterally from their

No. 674 89

90 FIELDIANA: GEOLOGY, VOLUME 10

life position. The matrix is hard and the bone soft, so that it has
not been possible to reveal detail in various regions. So far, this
specimen, a single, isolated vertebra, a maxillary tooth plate, and
two pairs of lower jaws are the only representatives of the genus
that have been definitely recognized. The collections include some-
what similar smaller jaws, fragmentary palates and various parts
of postcranial skeletons that may prove referable to the genus when
more is known concerning the full skeleton and range of variation.

Class REPTILIA

Subclass Parareptilia

Order Diadecta

Suborder Seymouriamorpha ?

Family Waggoneriidae fam. nov.

Waggoneria gen. nov.

Diagnosis. — Maxillary and dentary expanded medially to form
plates bearing several rows of interlocking teeth. Otic notch open,
with quadrate well forward of posterior termination of dorsal surface
of skull. Parasphenoidal wings very broad, extending laterally to
quadrate ramus of pterygoid. Lower jaws deep posteriorly and
heavy throughout. Articular bone proportionately large. Centra
of vertebrae amphicoelous posteriorly and opisthocoelous in extreme
anterior part of column. Neural arches broad and low, neural spines
short. Articular surfaces of zygapophyses nearly horizontal except
in first two vertebrae. Interclavicle T-shaped.

Waggoneria knoxensis1 sp. nov.

Type. — C.N.H.M.-U.R. 14, skull, lower jaws, six anterior
vertebrae and partial shoulder girdle.

Horizon and locality. — Upper part of Vale Formation, Clear Fork
group, Early Permian. Locality KF (Olson, 1948) at three-channel
hill, approximately seven miles north of Vera, Knox County, Texas.

Diagnosis. — As for the genus.

Skull. — No details of the dorsal surface can be obtained from
the type specimen. A reconstruction of the probable outlines is

1 The generic name is given in recognition of the long-continued aid that has
been given to students of vertebrate paleontology by the Waggoner estate of
Vernon, Texas. The specific name alludes to the county in which the specimens
were found.

OLSON: FAUNA OF UPPER VALE AND CHOZA

91

B

Fig. 38. Reconstructions of the skull of Waggoneria knoxensis gen. and sp.
nov. Based primarily upon type specimen. A. Dorsal aspect. B. Lateral aspect.

shown in figure 38, A and B. The position of the orbits is clear and
the general configuration is moderately accurate. The most interest-
ing features of the skull are the temporal region and the position of
the articulation of the lower jaw. There is no temporal fenestra,
but an otic notch is well developed. This notch appears to have been
open broadly, as in Diadectes and Procolophon. The articulation of
the lower jaws lies at the base of the notch. The quadrate, which

92

FIELDIANA: GEOLOGY, VOLUME 10

is poorly preserved, seems to have been similar in general aspects
to that of Diadectes.

Certain features of interest are revealed in the palatal aspect
(fig. 39). The posterior wings of the parasphenoid are present, and
the transverse and quadrate processes of the pterygoid are well
exposed. No other bones of the palate or of the basicranium are

Fig. 39. Ventral aspect of type specimen of Waggoneria knoxensis gen. and
sp. nov. X %.

revealed except a fragment, which is probably part of the basi-
sphenoid.

The left wing of the parasphenoid is moderately well preserved.
It consists of a broad, flat plate that extends laterally to the level
of the quadrate ramus of the pterygoid. The anterior margin is
curved dorsally. In these respects the parasphenoid is much like
that of Diadectes and not decidedly different from that of Seymouria.
Presumably the stapes passed above it from low in the otic notch
to the otic region of the brain case. There is a rather slender bone
in this area, but it cannot be properly developed without irreparable
damage to the parasphenoid and pterygoid.

OLSON: FAUNA OF UPPER VALE AND CHOZA

93

The preserved parts of the pterygoid show no definitive features.
The nature of the cranio-palatal articulation is not revealed.

Dentition and jaws (fig. 40, A, B, C). — Dentary and maxillary
teeth are preserved in the type specimen. Each of the tooth-bearirtg
bones is somewhat expanded medially and the shelf-like projections
oppose each other when the jaws are closed. The teeth are short,

B C

Fig. 40. Jaw and dentition of type specimen of Waggoneria knoxensis gen.
and sp. nov. A. Inner aspect of lower jaw and cross section at level of expanded
dentary. B. Ventral aspect of maxillary dentition of type specimen; drawn from
rubber cast. C. Ventral view of maxillary dentition of referred specimen, circles
indicating positions of broken teeth. X %.

slightly bulbous cones. There are four rows of teeth above and
at least four below.

The lower jaw is deep relative to its length, presumably in con-
nection with a crushing function of the teeth on the expanded
dentary. The articular is a large, strongly ossified bone, and the
sheathing dermal bones are thick.

Postcranium. — Parts of six vertebrae, clavicles and interclavicle,
fragments of the coracoids and part of one rib are preserved in the
type specimen. A single, isolated dorsal vertebra, C.N.H.M.-U.R.
15, is all that is known of the remainder of the column. The verte-

94

FIELDIANA: GEOLOGY, VOLUME 10

Fig. 41. Vertebrae and shoulder girdle of type specimen of Waggoneria
knoxensis gen. and sp. nov. A. Dorsal aspect of first six vertebrae. Atlas repre-
sented by centrum only. Right side of arches and spines somewhat restored.
B. Ventral aspect of centra of first six presacral vertebrae. C. Ventral aspect of
interclavicle, clavicles and partial coracoids.

brae of the type specimen (fig. 41, A and B) consist of the first six
presacrals. The centra are well preserved but most of the spines,
arches and zygapophyses are badly damaged. The centra of verte-
brae 3 to 6 are normal for primitive reptiles. A break between the
second and third vertebrae reveals the presence of an opisthocoelous
articulation of the centra. Neural arches and zygapophyses are
fairly well preserved on the left side of the column. The reconstruc-
tion in figure 41, A, shows their general condition in dorsal aspect

OLSON: FAUNA OF UPPER VALE AND CHOZA 95

with the right side and some of the spines restored. The evidence
for most of the reconstruction is sound but some details may be in
error. Vertebrae 4, 5, and 6 are alike in general structure and not
greatly different from the more posterior presacrals, as shown by
C.N.H.M.-U.R. 15, except that the zygapophyses and arches are
less broad. The arches are of the type common to primitive Early
Permian reptiles. They resemble those of Labidosaurus most closely

A B

Fig. 42. Dorsal vertebrae of Waggoneria knoxensis gen. and sp. nov. C.N.
H.M.-U.R. 15. A. Right lateral aspect. B. Dorso-anterior aspect. X 1.

but are considerably more flattened. Zygapophyses are large, but
proportionately less extensive than those in Captorhinus, Labido-
saurus or Diadectes. The arch of vertebra 3 is normal, as are the
posterior zygapophyses; the anterior zygapophyses, however, rise
sharply from the level of origin and are expanded medially to form
a secondary junction with the neural arch. A short, expanded
cervical rib is fused to this vertebra.

The axis is specialized. It is somewhat distorted and rotated
from its life position but the essential features are clear. The arch
is very broad, as are the posterior zygapophyses. The anterior
zygapophyses extend antero-laterally as distinct processes. Pre-
sumably these articulated with similarly extended processes of the
atlas, but the dorsal part of this vertebra is not preserved. The
centrum of the axis is specialized in the possession of a sharp ventral
keel. Between the axis and the atlas there is a small wedge-shaped
intercentrum. Little can be told about the atlas, since only the
centrum is preserved. The dorsal parts were lost or, as seems more
probable, were unossified. The centrum is nearly rectangular in
cross section. Anterior to the centrum, as seen ventrally, is a bone
that represents either an atlantal intercentrum or the posterior
margin of the occipital condyle, or parts of both. The articulation

96 FIELDIANA: GEOLOGY, VOLUME 10

of the vertebra and skull appears to have been single. The only
rib preserved is displaced from its natural position. It appears to
have been associated with the fifth or sixth presacral vertebra. The
rib is holocephalous, has a short shaft and is expanded distally.
The transverse process on the only known dorsal vertebra shows
that the ribs in this area were holocephalous as well.

Measurements mm.

Length of skull (snout to end of dorsal table) 116

Posterior width of skull (maximum) 90

Length of lower jaw (approx.) 108

Anterior dorsal vertebra (based on C.N.H.M.-U.R. 15)

Length of centrum (ventral) 12.5

Height of centrum (anterior) 12.8

Total height of vertebra 30 . 5

Width of posterior zygapophyses 27 . 2

Width of anterior zygapophyses 29.5

Relationships. — As yet no genus but Waggoneria can be assigned
definitely to the new family, Waggoneriidae. Various jaws, parts
of postcranial elements, and parts of palates that show some of the
characteristics of Waggoneria have been found. They differ with
respect to size and morphological detail, and some of them may
belong to other genera that should be included in the family. Addi-
tional collecting and preparation will probably increase the knowledge
of the known genus and perhaps bring to light other genera closely
related to it.

Broad neural arches, emphasis of the pleurocentral part of the
centrum and absence of temporal fenestrae place Waggoneria among
the primitive reptiles. The open otic notch and broad wings of the
parasphenoid indicate that it belongs in the Subclass Parareptilia.
Affinities within this subclass are with the Order Diadecta rather
than with the Order Chelonia. There are resemblances to the
Seymouriamorpha, Diadectomorpha and Procolophonia. The ver-
tebrae of Waggoneria resemble those of Seymouria more closely than
those of genera included in the other two suborders but, as stated,
the closest resemblance is to the vertebrae of Labidosaurus, a member
of the subclass Eureptilia. The temporal and quadrate regions are
similar to those of Diadectes and Procolophon and seem to be struc-
turally somewhat closer to Procolophon. The parasphenoid, on the
contrary, is more like that of Diadectes. It is possible that Waggoneria
will prove to be a representative of a heretofore unknown suborder
of these reptiles, but establishment of such a category must await

OLSON: FAUNA OF UPPER VALE AND CHOZA 97

more complete evidence; for the present the family is placed very
provisionally in the Seymouriamorpha. There is nothing in the
known structure of Waggoneria that could not have been derived
through modifications of Seymouria, and some species of this genus
might conceivably have been ancestral to it, whereas Diadectes is
too specialized in a number of respects, the palate, dentition, verte-
brae, etc., to be considered as a possible ancestor.

2. A NEW CAPTORINOMORPH REPTILE

Class REPTILIA

Subclass Eureptilia

Infraclass Captorhina

Order Captorhina

Suborder Captorhinomorpha

Family Captorhinidae

Captorhinoides gen. nov.

A number of specimens representing captorhinid reptiles have
been obtained from the upper part of the Vale and Choza. At
least one is very similar to Captorhinus isolomus of the Arroyo. It
may be that some of the fragmentary material may be similarly
referred, after it has been prepared and studied. In addition, how-
ever, there is captorhinid material that does not appear to be referable
to the genus Captorhinus. Much of it is so fragmentary and so poorly
preserved that generic reference will be impossible until much more
is known of the Vale and Choza captorhinids from more complete
specimens. One skull, however, is complete enough for profitable
study and the new genus erected in this section has been based
upon it. The specimen was found in a channel conglomerate near
the type specimen of Waggoneria knoxensis. The bone of the
dorsal and lateral surfaces had been destroyed by spalling. The
palate, basicranium, stapes and part of the jaws and dentition are
well preserved and form the principal basis for the diagnosis.

Diagnosis. — General configuration of skull similar to that of
Captorhinus. Stapes with broad foot, very large stapedial foramen,
and slender, tapering shaft. Basisphenoid-parasphenoid short, with
prominent transverse ridge near anterior end. Pterygoid with
quadrate process separated into short anterior process and broad
posterior plate, the two lacking osseous connection. Epipterygoid
with stout, rod-like ascending process and long cylindrical quadrate

98 FIELDIANA: GEOLOGY, VOLUME 10

process. Upper and lower jaws with three irregular rows of teeth.
Marginal teeth elongated and somewhat recurved anteriorly, grad-
ually diminishing in height posteriorly. Teeth of inner rows, low,
somewhat bulbous cones.

Captorhinoides valensis sp. nov.

Diagnosis. — As for the genus.

Type. — C.N.H.M.-U.R. 13, incomplete skull and jaws.

Horizon and locality. — Upper part of Vale Formation, Clear
Fork group, Early Permian. Locality KF (Olson, 1948), approxi-
mately seven miles north of Vera, Knox County, Texas.

Description and comparisons. — Throughout this section the
descriptions are augmented by comparisons with members of the
genus Captorhinus. Four species of this genus have been described
from the North American Permian but the taxonomy is not satis-
factory. It is not certain that the four species are all distinct, and
it is possible that certain specimens do not belong to any of the
named species. Falling in this latter category are at least some of
the specimens from the Permian fissure fills in the Arbuckle lime-
stone north of Fort Sill, Oklahoma. Much of the work of Price
(1935) was based on material from this locality. There are moder-
ately great differences in the basicranium, the middle ear and the
craniopalatal regions of the various specimens of Captorhinus that
have been examined, but the skulls do seem to show a continuity
of form which indicates that they are variates of a common pattern
rather different from that of Captorhinoides. In making comparisons
a specimen belonging to the Arroyo species Captorhinus isolomus
and material of Captorhinus sp. from the Oklahoma fissure fills have
been used.

The Dorsal Surface (fig. 43, A): Only in the region of the
orbit and the right maxillary is bone preserved. So far as it is possible
to tell there are no important differences between the dorsal surfaces
of Captorhinus and Captorhinoides, but it is entirely possible that
differences would be evident were the latter better preserved. The
orbits in Captorhinoides are large, but this feature is shared with
small skulls of Captorhinus. The internal cast of the temporal region
has a smooth, uninterrupted surface with no evidence of fenestration.
As in Captorhinus, the posterior rim of the dorsal surface of the skull
is smoothly rounded and shows no evidence of an otic notch.

Jaws and Dentition: Both upper and lower jaws are partially
preserved but the sheathing bone is badly damaged or absent, except

OLSON: FAUNA OF UPPER VALE AND CHOZA

99

Fig. 43. Captorhinoides valensis gen. and sp. nov., type C.N.H.M.-U.R. 13.
A. Lateral aspect of skull. B. Palatal aspect of skull. X 2.

anteriorly. The articulation of the lower jaw and the skull lies at
the extreme posterior end of the skull. As in Captorhinus, there
are multiple rows of teeth on both upper and lower jaws. A differ-
ence between the two genera exists in the presence of elongated
marginal teeth in the anterior half of the upper jaw of Captorhinoides.
This difference can hardly be considered of generic significance but
it may reflect some difference in the dietary habits of the species
of the two genera. Apparently Captorhinoides had recurved pre-

100 FIELDIANA: GEOLOGY, VOLUME 10

maxillary teeth as did Captorhinus, but poor preservation in the area
makes the determination uncertain.

Basicranium and Palate: The most interesting features of the
skull occur in these regions. They are shown in figures 43, B, 44,
and 45, together with comparative drawings of Captorhinus isolomus
and Captorhinus sp. Figure 44 shows the basisphenoid-parasphenoid
in ventral aspect. That of Captorhinoides is proportionately short
and differs in many details from either of the other two. In the
nature of the basipterygoid process of the basisphenoid, C. isolomus
is more or less intermediate between the extreme conditions shown
in Captorhinus sp. and Captorhinoides. Captorhinoides differs mark-
edly from the other two in the presence of a ridge-like cross connec-
tion between the latero-ventral flanges of the two sides of the
basisphenoid-parasphenoid .

Figure 45 gives comparative illustrations of the cranio-palatal
joint and associated osseous elements. Each illustration has been
drawn from the specimen, without reconstruction, to show the
cranio-palatal joint somewhat open. In life, of course, the basi-
pterygoid process fitted closely into the socket of the pterygoid-
epipterygoid complex.

The epipterygoid enters into the joint in each case. In Cap-
torhinus it makes up almost the entire articular surface for the
palate but in Captorhinoides it forms only the dorsal part. The
most striking difference, however, lies in the quadrate process of
the epipterygoid, which is present in Captorhinoides and virtually
absent in Captorhinus. Whether or not this process actually reached
the quadrate or whether it extended only to the posterior plate
of the quadrate process of the pterygoid is uncertain. As indicated
in the figure, the quadrate process of the pterygoid of Captorhinoides
has no osseous continuation from the short anterior part, which
lies on the posterior margin of the transverse process, to the posterior
plate.

This appears to be the condition that occurred during life and
not one due to post-mortem damage, since exceedingly delicate
features of the stapes are well preserved in the immediate area in
which the medial part of the process might be expected. The end
of the anterior process seems to have continued as soft tissue for
at least a short distance back of its osseous termination, and shows
no evidence of having been shortened by breakage. The posterior
plate likewise shows no evidence of having been continued anteriorly
by bone.

Fig. 44. Basisphenoid-parasphenoid of Captorhinoides and Captorhinus.
A. Captorhinoides valensis, C.N.H.M.-U.R. 13; X 2%. B. Captorhinus sp., M.C.Z.
1198; X 33^. C. Captorhinus isolomus, C.N.H.M.-U.C. 1702; X 2%.

bpt-proc

8PT-PROC

^-BS-PAS

B

Fig. 45. Basicranio-palatal articulation
of Captorhinoides and Captorhinus. A. Cap-
torhinoides valensis, C.N.H.M.-U.R. 13; X 4;
slightly restored and reversed to correspond
in position to B and C. B. Captorhinus sp.,
M.C.Z. 1198; X 4. C. Captorhinus isolomus,
C.N.H.M.-U.C. 1702; X 4. Abbreviations:
BPT-PROC, basipterygoid process; BS-
PAS, basisphenoid-parasphenoid; EPT, epi-
pterygoid; PT, pterygoid.

BPT-PROC

-i— B S- PAS

101

102 FIELDIANA: GEOLOGY, VOLUME 10

The remaining parts of the palate of Captorhinoides, so far as
they have been observed, differ only in minor details from those of
Captorhinus sp. and Captorhinus isolomus, and the differences are
no greater than those between the described species of Captorhinus.

The Stapes: This bone is well preserved on the left side of the
skull in the specimen of Captorhinoides. Details of structure in
ventral view are shown in figure 46 and the stapes of Captorhinus
isolomus, which resembles that of Captorhinus sp. closely in basic

A B

Fig. 46. Stapes of Captorhinoides and Captorhinus in ventral aspect. A.
Captorhinoides valensis, C.N.H.M.-U.R. 13, slightly restored; X 8. B. Captor-
hinus isolomus, C.N.H.M.-U.C. 1702; X 8.

features, is illustrated for comparison. The stapes of Captorhinoides
differs materially from that of any species of Captorhinus. Most
striking is the fact that it is much more slender and lightly con-
structed throughout. That these differences are due neither to
age nor size is suggested by the fact that even very small stapes of
Captorhinus sp. have the characteristic heavy structure.

The stapedial foramen of Captorhinoides is very large compared
to that of Captorhinus. This may have resulted merely from an
over-all reduction in the thickness of the various parts of the bone.
The dorsal process is slender but distinct, and similar in position
and orientation to that of Captorhinus.

Discussion. — The skull of Captorhinoides valensis has been shown
to differ from those of two species of Captorhinus in several aspects
usually considered to be of fundamental taxonomic significance.
On the basis of differences in the basicranium, the cranio-palatal
joint, the pterygoid and epipterygoid, and the stapes, the new genus
has been established. The striking differences in the stapes would
seem, in themselves, to indicate that Captorhinus and Captorhinoides
were markedly divergent. If it may be assumed that the stapes
functioned in hearing, it would appear that Captorhinoides had a
decidedly superior mechanism for transmission of vibrations from
the outer to the inner ear. This could be a basic advance of real

OLSON: FAUNA OF UPPER VALE AND CHOZA 103

significance. We do not know the total extent of variation of this
feature among the species of Captorhinus and thus cannot evaluate
the full significance of the difference. To a greater or lesser extent
this same difficulty is involved in evaluation of each of the several
differences. In spite of the rather inadequate bases for determining
the significance of the differences, they can hardly be of less than
generic significance and in some respects they suggest separation at
a higher level.

Captorhinoides could have been derived from Captorhinus. If
we assume this to be the case, certain of the presumed changes
have considerable interest as indicators of trends in evolution of
at least one line of the Captorhinomorpha. The basisphenoid-
parasphenoid, being shortened and broadened, approaches the primi-
tive pelycosaur condition more closely than does this region in
Captorhinus. Partial exclusion of the epipterygoid from the cranio-
palatal joint represents a trend toward the condition seen in several
reptilian lines, for example certain therapsids. It is not, however,
a change in the direction of primitive Lepidosauria, such as the
Eosuchia, which, on the basis of evidence from Youngoides (Olson,
1936; Olson and Broom, 1937), have preserved a meniscus that
appears to represent the foot of the epipterygoid. Even in the
lacertilians, the meniscus pterygoideus is present as an apparent
remnant of participation of the epipterygoid in the joint. In some
diapsids in the archosaurian line, however, the epipterygoid is
excluded from the joint.

Ossification of the quadrate process of the epipterygoid, although
it is a striking feature in itself, may be of little real significance.
A short quadrate process is present in various pelycosaurs and repre-
sents merely an ossification of a part of the quadrate process of the
palatoquadrate bar; a similar structure may confidently be inferred
in Captorhinus. The significance of the structure of this area lies
rather in the fact that the epipterygoid appears to replace the
quadrate process of the pterygoid functionally in Captorhinoides.
This specialization shows little morphological convergence to any
related group of reptiles. It is true that the quadrate process of
the epipterygoid is prominent in certain therapsids, especially in
advanced carnivorous types, and is carried over to mammals (in
the equivalent alisphenoid), but the development is actually quite
different from that seen in Captorhinoides.

The stapes is, as remarked, decidedly reduced. This trend is
one to be anticipated in the ancestry of a number of lines of reptiles.

104 FIELDIANA: GEOLOGY, VOLUME 10

Even primitive Lepidosauria, for example, appear to have a stapes
much reduced over that seen in Captorhinus. Marked stapedial
reduction occurs among the synapsids but only in the most advanced
groups. The stapes is large and heavy in the pelycosaurs and short
and stocky in such therapsids as the dicynodonts, gorgonopsians,
dinocephalians, and at least primitive therocephalians. Reduction
seems to have begun independently within the therapsid lines.
There is thus in Captorhinoides a general pattern of convergence
to two major groups of Eureptilia. Stapedial reduction also occurs
in the Parareptilia, as exemplified by the Chelonia.

Taken individually, the various changes suggest, in most in-
stances, a trend toward conditions seen in one or more groups of
reptiles. Such trends are often, and properly, taken as indications
of ancestral-descendant relationships. Inferences of relationships
based on single trends are, however, to be regarded with the greatest
caution; series of trends are infinitely more reliable. In the present
instance, if this philosophy be followed, it is apparent that the
series of trends which have been witnessed, when taken together,
do not suggest that Captorhinoides was evolving toward conditions
realized in any one of the major groups of reptiles.

3. LUNG FISH OF THE VALE

GENERAL CONSIDERATIONS

Ten specimens, all from the Vale Formation, have been identified
as lung fish. All are isolated teeth or teeth and jaw elements. Five
of the specimens were taken from a quarry in fine-grained, green
channel deposits in locality KF (Olson, 1948). Remains of fish are
abundant in this quarry and it is probable that many of the scattered
bones are skeletal elements of lung fish. It may be possible, when the
material has been fully prepared, to determine associations and to
gain some information concerning the skeletons of these dipnoans.
All five specimens from this locality are lower teeth and associated
jaw elements. The other five specimens occurred as follows: two
large partial lower teeth from coarse channels in locality KF near
the quarry; one very small, complete upper tooth from KF at the
"three channel hill locality"; a small, nearly complete upper tooth
from a conglomerate at locality KI,1 and a partial large upper
tooth from the "boulder locality" of KD.

1 Locality KI was investigated for the first time in 1948. It is located on
aerial photographs as follows: CGV 5 24, Corners at 1.6-4.5, 1.5-3.3, 2.2-4.5,
and 2.2-3.2 (see Olson, 1948, for indexing system).

OLSON: FAUNA OF UPPER VALE AND CHOZA 105

Teeth of lung fish are abundant at various localities in beds of
the Wichita group of the Early Permian in north central Texas but
are rare in the Clyde and Arroyo formations of the Clear Fork group.
The great majority pertain to the genus Sagenodus. Proceratodus?
favosus is represented by a single specimen from the "Permian of
Texas" (Cope, 1884; Hussakof, 1911; Romer and Smith, 1934).
Gnathorhiza has been found in beds of Wichita and Clear Fork ages,
but data on the majority of the specimens known from the Permian
are not sufficiently detailed to allow them to be placed stratigraphi-
cally with any accuracy. One, an upper tooth collected in Baylor
County, Texas, is definitely of Arroyo age (Olson, 1939).

Lung fish are more abundant in the Vale than in the Arroyo,
but the abundance by no means approaches that of dipnoans in the
Wichita. Sagenodus, the common Pennsylvanian and Wichita
genus, has not been found in the Arroyo and collecting to date has
not revealed its presence in the Vale. All specimens from the Vale
may be referred to the genus Gnathorhiza. One specimen, C.N.H.M.-
U.F. 96, from locality KI, is an upper tooth that differs in no im-
portant respect from the specimen from the Arroyo, C.N.H.M.-U.F.
95, and clearly belongs to the same species. The remaining nine
specimens, however, are much larger, except for C.N.H.M.-U.F. 88,
and differ markedly in a number of features from any heretofore
described species of Gnathorhiza.

The taxonomy of the genus is rendered difficult by the fact that
Gnathorhiza pusillus (Cope), from the Pennsylvanian of Illinois, is
an upper tooth plate, whereas all others from the Permian beds
below the Vale, except for the one from the Arroyo, are lowers.
Romer and Smith (1934) have suggested that it is desirable to con-
sider the Permian representatives as specifically different from the
Pennsylvanian species, G. pusillus, and retain the species G. serrata
(Cope) rather than recognize only a single species as did Hussakof
(1911). Such a differentiation was stratigraphic rather than morpho-
logic, since the only specimens known were the upper tooth from the
Pennsylvanian and the lowers from the Permian. The case is some-
what strengthened by the one upper plate from the Arroyo. This
tooth differs from the type of G. pusillus in the lack of denticulation
on the ridges and in the stronger development of the anterior ridge.
Also, it is considerably larger, but this may have little real meaning.
These two upper plates furnish sufficient morphological evidence
for the recognition of two species. The problem of associations still
remains, since it cannot be demonstrated that the upper tooth from

106 FIELDIANA: GEOLOGY, VOLUME 10

the lower Permian actually belongs to the same species as the lowers.
The probability that this is the case seems high, however, since all
the known lowers are very similar and show no evidence of two
species in the pre- Vale Permian. On the basis of this probability,
I have followed Romer and Smith in recognizing the Permian
species G. serrata (Cope) as distinct from the Pennsylvanian species
G. pusillus.

Romer and Smith (1934) suggest that Gnathorhiza is a Permian
representative of the family Lepidosirenidae, in opposition to the
opinion of Stromer (1910) that the resemblances of the teeth to
those of Lepidosiren and Protopterus are convergent. The many
similar features in the dentitions of these three are suggestive of a
real relationship. Such similarities, however, might be due to con-
vergence. There is no way of settling this matter from the evidence
now available. As will be shown, the lower plates of the Vale speci-
mens show a trend away from rather than toward the condition of
the living lepidosirenids but, again, this offers no proof that affinities
do not exist. Inasmuch as there are notable resemblances between
Gnathorhiza and the lepidosirenids and no positive evidence that
they are not related, and since there is no other family of the Dipnoi
to which Gnathorhiza could belong, I have tentatively accepted the
placement of the genus in this family.

taxonomy

Of the ten identified specimens of dipnoans from the Vale, all
of which belong in the genus Gnathorhiza, nine belong to one species
and one to another. Among the nine are seven lower tooth plates
and two uppers. The single representative of the other species
consists of an upper tooth plate. So comparisons may be made, the
new species, represented by the nine specimens, is considered first.

Class OSTEICHTHYES
Subclass Choanichthyes

Order Dipnoi

Family Lepidosirenidae

Genus Gnathorhiza

Gnathorhiza dikeloda sp. nov.

Type. — C.N.H.M.-U.F. 91. Lower tooth plate and splenial
(fig. 47, A and B).

OLSON: FAUNA OF UPPER VALE AND CHOZA

107

Horizon and locality. — Upper part of Vale Formation, Clear Fork
group, Early Permian, locality KF (Olson, 1948), Knox County,
Texas, about seven miles north of Vera, Texas.

Referred specimens.— C.N.H.M.-U.F. 87-90, 92-94, C.N.H.M.-
U.C. 1668. C.N.H.M.-U.F. 87 from locality KD, remainder from
KF.

Diagnosis. — Lower tooth with inner ridge forming narrow,
strongly serrated blade. Anterior moiety of blade at least two

B

Fig. 47. Lower teeth of Gnathorhiza. A. Inner aspect of the type of G.
dikeloda sp. nov., C.N.H.M.-U.F. 91; X llA. B. Dorsal aspect of type of
G. dikeloda sp. nov., C.N.H.M.-U.F. 91; X 1& C. Dorsal aspect of type of G.
serrata (Cope), A.M.N.H. 7258 (after Hussakof); X 1^.

times length of posterior moiety, possessing five or six strong denticu-
lations. Single radiating ridge short and serrated on external slope
only. Posterior moiety of blade strongly curved laterally and only
slightly serrated. Upper tooth with long, compressed inner blade
and two short radiating ridges. Inner blade strongly angulated
anterior to radiating ridges and bearing three strong denticles.
Posterior moiety of inner ridge finely denticulated and uncurved.
Radiating ridges with denticulate sloping external margins.

Description and discussion. — Adults of the species are much larger
than those of G. serrata or G. pusillus, as shown in Table 1. The
shearing function of the blades of the teeth are even more highly
developed than in the other species by virtue of the elongation of
the anterior moieties of the inner ridges of both the upper and lower

108

FIELDIANA: GEOLOGY, VOLUME 10

tooth plates. This difference is clearly shown in the LAM/LPM
column in Table 1.

Each of the differences is of such a high order that there is no
need to demonstrate its validity by statistical analysis.

Table 1.— COMPARISON OF MEASUREMENTS OF
GNATHORHIZA DIKELODA AND G. SERRATA

Total
length1

Length of
anterior
moiety

G. dikeloda

Length of

posterior

moiety

Length of

radiating

ridge

LAM*
LPM

C.N.H.M.-U.F. 90..
C.N.H.M.-U.F. 94..
C.N.H.M.-U.F. 93..
C.N.H.M.-U.F. 92..
C.N.H.M.-U.F. 91. .

. 28.0
. 27.0
. 30.0

. 30^5

21.5
20.0
24.0

25.2
G. serrata

9.0

9.0
10.0

8.8
10.2

5.2
4.8

5^2
6.0

2.4
2.2
2.4

2^4

A.M.N.H. 7258
A.M.N.H. 8014

10.8
. 12.2

6.2

8.2

4.7
5.3

1.3
1.5

Table 2.— PARAMETERS OF SAMPLE OF
GNATHORHIZA DIKELODA

Measurements N M

Total length 4 28.9±0.81

Length of anterior moiety 4 22.7±1.17

Length of posterior moiety 5 9.4 ±0 . 25

1.65±0.59
2.35±0.83
0.65±0.21

The nature of the upper teeth in G. dikeloda is less readily deter-
mined. The only adult tooth is C.N.H.M.-U.F. 87 and this is only
a small part of the inner ridge and of the two radiating ridges (fig. 48).
The short portion of the inner ridge that is present is somewhat
straighter than that in G. serrata. More information is provided by
a very small tooth, C.N.H.M.-U.F. 88, whose total length is only
8.9 mm. The tooth appears to be an unerupted plate of an immature
individual. The general characteristics show, with little doubt,
that this was the type associated with the lowers of the adults.
This belief is strengthened by the fact that the preserved parts of

1 Measurements in millimeters, taken as follows: Total length equals distance
from the anterior extremity of the tooth to the posterior extremity measured along
a line parallel to the longitudinal axis of the jaw. Length of anterior moiety
equals the distance from the position of intersection of the radiating ridge and
the inner ridge to the anterior extremity of the tooth in a direct, straight line.
Length of posterior moiety equals the distance from the point marked by the
intersection of the radiating ridge and the inner blade to the posterior extremity
of the tooth in direct, straight line. Length of radiating ridge is the distance from
the intersection as above to the lateral extremity of the ridge.

2 LAM, length of anterior moiety; LPM, length of posterior moiety.

OLSON: FAUNA OF UPPER VALE AND CHOZA

109

the large upper are identical with those in the complete small tooth
in every way except size. The principal features of this upper tooth
and comparisons with upper teeth of G. serrata are shown in figure 48.

Gnathorhiza serrata (Cope)

A single tooth, C.N.H.M.-U.F. 96, from the Vale is referred to
this species. This tooth (fig. 48, B) is identical, except for a slight

Fig. 48. Upper teeth of Gnathorhiza. A. G. pusilliis (Cope), type, C.N.H.M.-
U.C. 6508; X 2V2. B. G. serrata (Cope) from the Vale, C.N.H.M.-U.F. 96; X 2]/2.
C. G. serrata (Cope) from the Arroyo, C.N.H.M.-U.F. 95; X 2XA- D. Lepidosiren;
X2Y2. E. G. dikeloda sp. nov., immature individual, C.N.H.M.-U.F. 88; X 1Y%.
F. G. dikeloda sp. nov., C.N.H.M.-U.F. 87; X 1x/2.

size difference, with the upper tooth of G. serrata from the Arroyo.
It was found at locality KI. So far as can be told, the horizon is
essentially the same as that from which the five specimens of G.
dikeloda were obtained in locality KF. In this single tooth there is
evidence that the species known from the Arroyo continued un-
changed into the Vale.

4. THE SKULL OF GNATHORHIZA DIKELODA OLSON

It was stated above (p. 105) that teeth of the dipnoan Gnathorhiza
occur in beds of Late Pennsylvanian and Early Permian age, extend-
ing to the top of the Vale Formation of the Clear Fork group.
Recent work has shown their presence in the Choza beds, as well.
Three species have been recognized from teeth, G. pusillus from the
Pennsylvanian, G. serrata from the Arroyo and Vale formations of
the Early Permian Clear Fork and apparently from the Wichita

110

FIELDIANA: GEOLOGY, VOLUME 10

PAS

Fig. 49. Parasphenoid and associated elements of G. dikeloda. A. C.N.H.M.-
U.F. 175, ventral aspect. B. C.N.H.M.-U.F. 168, ventral aspect. C. C.N.H.M.-
U.F. 171, dorsal aspect, showing inverted plate B with exoccipital process. D.
C.N.H.M.-U.F. 182, ventral aspect, showing cranial rib. CR, cranial rib; EO,
exoccipital; PAS, parasphenoid. All X %.

group as well, and G. dikeloda from the Vale and Choza. The last-
named species, described on page 107, was founded on a lower tooth
and jaw. Disarticulated skull plates were abundant in the deposits
from which the type and referred specimens were obtained and
many of these pertained to G. dikeloda. Using these elements I
have attempted to reconstruct the skull of G. dikeloda and to use
the skull as a means of determining the taxonomic and phylogenetic
position of the genus. Skull parts of the other species are not known.
About 200 individual skull elements have been studied. Those
that have contributed most to the interpretation are illustrated

OLSON: FAUNA OF UPPER VALE AND CHOZA

111

in figures 49 to 52. In only three instances has any articulated
material been found and this has not been particularly instructive.
All the plates, however, have been obtained from fine-grained
channel deposits in locality FK (Olson, 1948) in Knox County,
Texas. Mixed with the bones of the lung fish are jaws, skull plates,

Fig. 50. Jaws of G. dikeloda. A-F. Lower jaws in medial aspect. G.
Upper jaw in lateral aspect. A, C.N.H.M.-U.F. 197; B, C.N.H.M.-U.F. 198;
C, C.N.H.M.-U.F. 196; D, C.N.H.M.-U.F. 91, type of species; E, C.N.H.M.-
U.F. 118; F, C.N.H.M.-U.F. 169; G, C.N.H.M.-U.F. 204. All X H-

girdle elements and limb bones of trimerorhachid amphibians and
vertebrae of Dimetrodon and Waggoneria.

With one exception every type of dipnoan bone that has been
observed has a frequency of 4 or more, and it seems safe to assume
that all ossified parts of the skull, with the possible exception of
very small bones, have been found. The size of the various elements
is such that the bones could not have come from the small species,
G. serrata, which does occur in the Vale. Furthermore, no teeth
of this species have been found at locality KF. There is little doubt
that all of the elements belong to the single species G. dikeloda.

In a study based on fragmentary materials such as those available
for this work, the probability of errors is always high — errors of both
major and minor proportions. It is almost certain that some modifi-
cations in the reconstructed skull pattern will be necessary in the

Fig. 51. Skull elements of G. dikeloda. A-M. Median elements, oriented
with anterior ends toward top. N-0. Lateral element Y1+Y2. A, C.N.H.M-
U.F. 203, plate B in dorsal aspect; B, C.N.H.M.-U.F. 175, plate B in ventral
aspect, showing exoccipital; C, C.N.H.M.-U.F. 175, plate B in ventral aspect,
showing exoccipital; D, C.N.H.M.-U.F. 185, plate B in dorsal aspect; E, C.N.H.M.-
U.F. 171, plate F in dorsal aspect; F, C.N.H.M.-U.F. 173, plate F in dorsal aspect;
G-M, plate D in dorsal aspect, C.N.H.M.-U.F. 178, U.F. 166, U.F. 187, U.F. 174,
U.F. 165 and U.F. 164, respectively; N and 0, plate Y1+Y2 in lateral aspect with
anterior end to the right, C.N.H.M.-U.F. 205 and U.F. 199 respectively. All
X %.

112

K

L

Fig. 52. Lateral skull elements of G. dikeloda. A-I, plate M+L1+L2+K
with orbital margin toward bottom, C.N.H.M.-U.F. 179, U.F. 176, U.F. 176,
U.F. 183, U.F. 204, U.F. 173, U.F. 177, U.F. 181, U.F. 183, respectively. J and
K, plate J with ventral margin in upper right hand corner, C.N.H.M.-U.F. 191,
U.F. 204, respectively; L and M, plate J with anterior end to right and dorso-
medial toward top, C.N.H.M.-U.F. 175, U.F. 181, respectively; N, C.N.H.M.-
U.F. 184, "squamosal" element in lateral aspect with dorso-posterior portion
toward top (dotted outline reconstructed from rather poor impression in matrix).
All X H.

113

114

FIELDIANA: GEOLOGY, VOLUME 10

event that articulated skulls are found. So far as field investigations
have progressed, however, the chances of finding articulated materials
seem to be poor and an attempt to understand the skull, even though
the restorations may be inaccurate in some parts, seems justified

MI + LI + L2+K

Sq \UJ

B

Fig. 53. Reconstructions of skull of G. dikeloda. Solid lines represent visible
bones, broken lines those concealed by the surface of the skull. A. Dorsal aspect.
B. Lateral aspect. Approximately X % of adult skull. Lettered bones based on
system of Westoll (1949). CR, cranial rib; OM, orbital margin; PAS, parasphe-
noid; Sq, "squamosal;" UJ, upper jaw.

in view of the information that such a study can yield. Every effort
has been made to avoid errors and the more questionable parts of
the restorations are documented in the text. The comments on
taxonomy and phylogeny on pages 120-124 are, of course, only as
valid as the interpretations of the identities and positions of the
bones.

THE SKULL ELEMENTS AND THE RESTORATIONS

In the following paragraphs the bones of the various series are
described in some detail and their probable positions in the skull
are given. The reader may best maintain his orientation by reference

OLSON: FAUNA OF UPPER VALE AND CHOZA 115

to the reconstructions (fig. 53), but he should consult figures 49 to
52 for an evaluation of the evidence. The terminology of Westoll
(1949) has been adopted so far as it is applicable to the elements
described. The fossils offer little evidence on homologies of the
various bones so that these have been taken from various sources
as noted in the text. For the reconstructions, an effort has been
made to approximate the mean sizes of the different bones in the
hope that this would produce a reasonably integrated whole.

Palate, jaws and teeth (figs. 49 and 50). — The parasphenoid and
the upper jaw, usually called pterygo-palatine, make up the palate,
as in most dipnoans. The principal features of the parasphenoid are
well shown in figure 49, A and B, and need little additional comment.
The basal, posterior spur is constant in the species, and the posterior
part of the dorsal surface is deeply grooved to receive a large noto-
chord. The parasphenoid is typically dipnoan and presents no
unusual major features. Three well-preserved and seven partial
parasphenoids have been found. There is some variation in length
and width and considerable variation in thickness.

Only two tooth-bearing upper jaws have been found, which is
in rather odd contrast to the dozen lowers. The single element of
the upper jaw corresponds closely to that of other lung fish. It
is proportionately broader and shorter than that in Protopterus and
Lepidosiren but otherwise much the same. There is no reason to
doubt that the upper jaw was associated with the expanded anterior
end of the parasphenoid in typical dipnoan fashion. There was a
moderately strong antero-median symphysis between the right and
left jaws.

Several fairly well-preserved lower jaws and teeth have been
recovered, plus some fragmentary remains, to make a total of
twelve specimens. Best preserved is the lower jaw and tooth
described above (p. 107) and designated as the type of the species,
C.N.H.M.-U.F. 91 (fig. 50, D). Specimens obtained since the time
that the description was written have added little to what was then
known. Only a single lower jaw element has been identified, that
called splenial or coronoid by various workers on modern lung fish.
Anteriorly, this element carries the very long, sectorial lower tooth
and medial to the anterior margin of this tooth it forms a strong
symphysis with the opposite jaw. Posterior to the tooth, the jaw
thins rapidly and is projected dorsally into a thin "coronoid process."
The general pattern is much the same as that in Protopterus, Lepido-
siren and Epiceratodus, but the posterior ramus is proportionately

116 FIELDIANA: GEOLOGY, VOLUME 10

thinner in Gnathorhiza and there is no evidence of a Meckelian
orifice such as is found in recent genera. It would appear that the
inner margin of the basal part of the ramus had degenerated to a
greater degree than is the case in living lung fish. No small element
is to be found below the splenial. This element is set in a deep
notch in Lepidosiren and Protopterus. No such notch occurs in
Gnathorhiza. As in modern dipnoans, the articular part of the lower
jaws appears to have been an unossified portion of Meckel's cartilage.

A somewhat puzzling relationship exists between the upper and
lower teeth. Lower teeth have an exceedingly long, serrate, anterior
blade. Large upper teeth do not show any such development. If
the lower and upper jaws are placed in the position consistent with
the condition in Protopterus and Lepidosiren, which seems logical
in view of the morphological similarities of the teeth and jaws in
the three genera, the long lower blade projects far beyond the anterior
limit of the upper tooth. A very small upper tooth, described above
(p. 108), has a long anterior blade that would occlude with the
anterior part of the lower blade, but no large upper tooth shows this
structure. The anterior margin of two well-preserved upper teeth
seems to be smooth. Whether the small tooth does not actually
pertain to this species or whether the anterior blade and any support-
ing structure that it may have had were lost by wear cannot be
determined from the material at hand. In all respects, except size
and the long blade, the large and small upper teeth are similar. The
problem appears to be insoluble at present but, in any event, it is
evident that in the adult the anterior part of the lower tooth did
not meet an opposing blade of the upper. It may, however, oppose
the "vomerine" teeth, whose position may be inferred from tubercles
observed on the ventral surface of the most anterior element of the
median series of dermal roofing bones.

Median dorsal series {fig. 51, A-M). — Three types of median
plates have been observed, each represented by several specimens.
Their median position has been inferred from their bilateral sym-
metry and from the presence of longitudinal structures that pre-
sumably lay along the midline. Representatives of each type are
shown (fig. 51) and their positions in restoration (fig. 53). Two of
the three median elements have distinctive features that define
their positions clearly. A number of plates (fig. 51, B and C; also
fig. 49, C, EO) possess a ventral process that corresponds very
closely to the exoccipital in Protopterus. In no single plate in which
the ventral side is exposed have both exoccipital processes been

OLSON: FAUNA OF UPPER VALE AND CHOZA 117

preserved, but right and left exoccipitals have been observed on
different plates. Two plates that carry this process have a curving
posterior distal margin and one has a posterior median projection.
This permits association of these plates with another (fig. 51, A)
that shows the full posterior margin in dorsal aspect, as well as much
of the outline of the lateral margin of the plate. It seems evident
from the presence of the exoccipitals and the configuration of the
posterior margin of the plates that this median plate lay at the
back of the skull in the position indicated in the restorations. It
corresponds to plate B of Westoll (1949).

Two complete plates and several fragments represent another type
of median plate (fig. 51, E and F). The outline in dorsal and ventral
aspect is roughly flask-shaped and corresponds closely to the out-
line of the rostral plate, dermo-ethmoid of Bridge (1898) and others,
in Protopterus and Lepidosiren. The posterior margin of the smaller
plate (fig. 51, F) is emarginated, presumably as the result of incom-
plete ossification. The ventral surface carries a pair of strong,
rounded tubercles that probably mark the positions of a pair of
vomerine teeth. These are an integral part of the plate with no
evidence of separate origin. That these plates represent anterior
members of the median series seems certain and, as such, they
correspond to plate F of Westoll (1949).

There is little definitive about the third type of median plate
(fig. 51, G-M). These plates are thin and in most instances poorly
ossified. The edges are feathered and irregular. A rough diamond
shape is characteristic. The end interpreted as posterior is some-
what flattened and, in some instances, seems to carry a short posterior
spur that presumably passed under the more posterior median
element (fig. 51, M). The anterior margin normally has a slight,
posteriorly directed emargination. Since this type of plate is clearly
median, there seems no alternative to the conclusion that it lay on
the dorsal midline of the skull between plates B and F, and thus
is comparable to plate D of Westoll (1949).

G. dikeloda appears to have had a midline series of three plates.
This is in contrast to Epiceratodus, Lepidosiren and Protopterus,
which have but two, but very similar to Ceratodus sturii Teller
(interpretation of Westoll, 1949, fig. 9) and, in some respects to
Sagenodus.

Lateral plates (fig. 51, N and 0; fig. 52). — Interpretation of the
lateral plates has been more difficult and conclusions are less certain
than in the cases of the palate, jaws, and median plates. The

118 FIELDIANA: GEOLOGY, VOLUME 10

reconstructions, of course, show the plates with definite outlines
and in definite positions, but it must be realized that the certainty
is not as great in some instances as figure 53 might indicate. The
probabilities of accuracy for each set of plates are considered in
the following paragraphs.

Two types of nearly flat plates, somewhat rounded in outline,
have been found, each represented by a considerable number of
specimens. Both types are asymmetrical and cannot have lain in
the midline. The configuration of the larger series of plates is shown
in figure 52, A-I. One margin of this type of plate is smoothly
finished along a slightly asymmetrical, concave surface. The
asymmetrical triangular apex of the opposite side may be fitted
nicely into the recess created by the margins of median plates F
and D (see fig. 53, A). In this position the curved margin lies in
the vicinity of the orbit and appears to constitute the dorsal orbital
rim. This type of plate can be placed in position with considerable
confidence.

The smaller rounded plates (fig. 52, J and K) have fewer defini-
tive characters. The shape is moderately constant and two small
features aid in placement. On one margin there is a projecting
shelf that must have passed beneath an adjacent element. Flanking
this shelf is a short, smoothly finished margin much like the orbital
margin of the larger plates. If the small plate is placed so that the
smooth margin forms a posterior continuation of the orbital margin,
the projecting shelf then articulates with the larger more anterior
plate and a reasonable relationship to plate D exists. A space is
left in the area created by the tapering margins of plates D and B
but this is explained, perhaps, by the fact that the adjacent margin
of the small plate tapers to a poorly defined, feathered edge that
suggests incomplete ossification. The same type of edge occurs on
plate D, whereas the margins of B are reasonably well developed.

The position of the two rounded plates seems fairly well estab-
lished. The precise locations may be slightly in error but the general
area can hardly be incorrect. It is difficult to be certain of homologies
but the positions strongly suggest that the larger plates correspond
to Westoll's M+L2+L1+K and the smaller to his plate J.

Another type of lateral plate occurs in the deposits, a long, thin,
wedge-shaped bone with a strong spur at one corner of the border
(fig. 52, L and M). The position of this plate is by no means certain
but it may at least be placed in a reasonable position. There is, of
course, the possibility that it does not belong to Gnathorhiza at all,

OLSON: FAUNA OF UPPER VALE AND CHOZA 119

but it certainly finds no reasonable place in the skulls or postcrania
of any other animal known from the deposits, and the structure of
the bone is the same as that of other skull plates of Gnathorhiza.
One margin of this plate fits moderately well against the lateral
margin of median plate B, if the broader end, which is well finished,
is considered to be posterior. One surface of this plate, presumably
ventral, gives the appearance of having received a flat spur from a
bone that lay latero-ventral to it. Such a spur occurs on an element,
described below, that is labeled 71+72 in figure 53 and located
with some confidence. At the postero-lateral margin of the lateral
plate under discussion, as oriented, occurs the strong spur that
projects ventrally and seems to fit into the notch created by a
posterior process of 71+72. These features, taken together with
the fact that there is no other plausible place where the bone might
lie in the skull, have been the basis of its placement. In this position
it would, presumably, be equivalent to element / of Westoll.

Four fairly well-preserved specimens and some fragments give
evidence of the rather complex bone that is thought to have lain
latero-ventral to element I. The bone is best understood by reference
to figure 51, N and 0. In the orientation indicated in the restora-
tion (fig. 53, B), this bone consists of an anterior ventral process,
a broad dorsal plate and a short posterior spur. The ventral edge
is rounded and well finished, as if it marked part of the skull margin.
The crescentic recess above the anterior process has a very thin,
knife-like edge unlike that found in the orbital margin. This, among
other things, makes it improbable that this bone was associated
with the orbit, as its shape might otherwise suggest. If the bone
did not lie in the orbital region, the indicated position must be
correct. There are several details that point in this direction. The
dorsal plate is very thin and irregularly grooved as if it inserted
under an adjacent bone. It will be recalled that the under surface
of element / gave indication of carrying such a bone. The posterior
spur is well suited to articulate with the ventral spur of I. The
anterior process could well be a quadrate process and in the orienta-
tion suggested it passes to the proper area. A well-defined groove
passes anteriorly and curves slightly dorsally from the posterior end
of the base of the dorsal plate to the anterior crescentic incisure.
This appears to show the course of a latero-sensory canal which
corresponds closely to that on 71+72 of various late Paleozoic
dipnoans (see, for example, Westoll, 1949, fig. 8).

One other feature of importance in the placement of this element
is the nature of the inner surface of the anterior quadrate process.

120 FIELDIANA: GEOLOGY, VOLUME 10

Since the importance of this feature becomes apparent only when
its probable relationship to a bone so far undescribed is recognized,
a digression to consider the latter is in order. In recent lung fish,
of which Protopterus may be taken as an example, the articulation
of the jaws is accomplished by cartilage, Meckel's cartilage in the
lower jaw and the quadrate cartilage in the skull. Lying lateral
to the quadrate cartilage is a thin, spatulate, dermal bone that
overlies a descending process of the large posterior roofing element
of the skull. The ventro-anterior end of the spatulate element
is expanded into a thin but deep condyloid process that, capped
by cartilage, aids in the jaw articulation. The homology of this
element has been variously interpreted, perhaps the most logical
interpretation being that it is squamosal. A similar element, known
from only one specimen (fig. 52, N), has been found in the Gna-
thorhiza-hearmg sediments. The condylar part is damaged but
the remainder is very like the "squamosal" of Protopterus. If this
element lay in a position similar to that in Protopterus, it would pass
to the anterior process of the bone discussed in the preceding para-
graph and identified as 71+ Y2. The inner surface of the anterior
process of the latter is strongly concave, opening ventro-medially,
precisely as would be the case had it received that dorso-posterior
end of the small "squamosal" element. This is believed to have
been the case.

DISCUSSION

It was hoped when this study was undertaken that positive
evidence concerning the position of Gnathorhiza with respect to the
living Lepidosirenidae might be forthcoming. Although results
have been unsatisfactory in this regard, a number of interesting
items that have come to light may be considered briefly. Romer
and Smith (1934) suggested an early separation of the Ceratodontidae
and Lepidosirenidae, recognizing a Pennsylvanian proceratodont and
referring Gnathorhiza to the family Lepidosirenidae. Stromer
(1910, 1936 and 1938) has argued strongly that the lepidosirenids,
excluding Gnathorhiza from the group, originated from the cerato-
dontids late in the Mesozoic and that the resemblances in dentition
between Gnathorhiza and Protopterus and Lepidosiren were the
result of convergence. Dollo (1896) and Agar (1906) imply a
similar relationship among living lung fish, with Epiceratodus the
most advanced. The problem involved is clear cut and simple,
namely, whether the differentiation was pre-Triassic, presumably

OLSON: FAUNA OF UPPER VALE AND CHOZA 121

in the Permo-Carboniferous, or whether it was post-Triassic, pre-
sumably in the Cretaceous. Solution is not an easy matter.

Until now, only teeth of Gnathorhiza have been available for
study. The work of Westoll (1949) has greatly amplified our
knowledge of the patterns of skull evolution in the dipnoans of the
Paleozoic. Evidence concerning skull evolution in the Mesozoic is
scant. Both Westoll (1949) and Stromer (1938) have discussed the
evidence, the latter in some detail, and both have concluded that
the case for late origin of the lepidosirenids from a ceratodont stock
is to be preferred. It would appear that the principal basis for such
a conclusion, as both writers suggest, is the absence of any remains
of lepidosirenids from the Mesozoic, coupled with the facts that
the morphological pattern of the lepidosirenids could have been
derived from that of the ceratodontids and that late Mesozoic teeth
are highly variable.

Now that many details of the skull of G. dikeloda are available,
it is possible to study the resemblance of this skull to those of other
Paleozoic lung fish, and to Protopterus and Lepidosiren. A considera-
tion of the possible Paleozoic ancestors shows that the most probable
source of Gnathorhiza is the genus Sagenodus. Gnathorhiza could
have been derived from this genus both from the aspects of time and
morphology, and in view of the resemblances of plates B and D
in the median series and J, J, and M+L2+L1+K in the lateral
series and the fact that the necessary dental modifications, while
striking, would not have been prohibitively drastic, Sagenodus may
well have occupied the ancestral position. Assuming this to have
been the case, the following changes would appear to have occurred.
Element D of the median series expanded at the expense of the paired
element E, which is lost in Gnathorhiza. F has enlarged. Q and N,
plus the circumorbital bones 2, 3 and probably 4, are gone, and the
orbital margin is formed by M+L2+L1+K and J. There is no
element X in Gnathorhiza so far as known. Yl and Y2 have fused
and H is absent. J has become longer and narrower but has main-
tained its position. Y1+Y2 have developed a strong quadrate
process that appears to have overlain the "squamosal."

The dermal bones appear to have become more deeply set so
that there is no trace of grooves for the latero-sensory organs except
on Y1+Y2. Most skull bones have lost intimate articulation with
their neighbors and, except adjacent to such structures as the orbits
and skull margins, tend to "feather out" toward the edges. Elements
D and J are very thin but the others have maintained considerable

122 FIELDIANA: GEOLOGY, VOLUME 10

thickness. The parasphenoid and jaws have changed little but the
dentition has modified to a strictly sectorial type. The only bone
remaining in the brain case is the exoccipital element. A strong
cranial rib is present.

As a result of these changes, Gnathorhiza approaches rather closely
the patterns seen in Protopterus and Lepidosiren. Assuming for
the moment that Gnathorhiza may be considered ancestral to the
living lepidosirenids, additional changes necessary to produce
Protopterus or Lepidosiren would not be great and would seem to
represent a continuation of some of the trends established in Gna-
thorhiza. Continued loss of bone would account for disappearance
of the already thin elements D and J. Element / would have dis-
appeared, and Y1+Y2 and B would have continued to sink deeper
below the surface. M+IA-\-L+K would be most drastically modified
of any of the elements that did not disappear, remaining for the
most part superficial but being elongated into the rather remarkable
processes found in the two living genera. Jaws and dentition would
have undergone only slight modifications. Such changes are certainly
plausible.

With this evidence alone the case seems fairly strong. The
changes from Sagenodus to Epiceratodus, however, are different only
in a few points. Westoll's circumorbital bone 4, bone X and bone /
are present in Epiceratodus. All are small and, although only I
has been identified in Gnathorhiza, the others might have been
present but small and hence not found. None of these are found in
the lepidosirenids. D and J are found in Gnathorhiza and not in
Epiceratodus, but Ceratodus sturii Teller, from the Triassic, has
D strongly developed. This form, in some respects, appears to be
intermediate between Sagenodus and Epiceratodus. Unlike Gna-
thorhiza, C. sturii lacks J and /, and M+L2+IA+K is elongated.
The circumorbital series, as interpreted, is complete in contrast to
that inferred in Gnathorhiza. If the changes from Sagenodus to
Epiceratodus are carried through the C. sturii stage, a reasonable
point of departure for the lepidosirenid type is reached at about
the Epiceratodus stage.

There is apparent in evolution, in these lines as in so many
others, a pattern of comparable changes and similar trends in
series that are at least ordinally related. Striking, in the genera
under consideration, is the fact that Gnathorhiza has become highly
modified in the Early Permian, whereas the first record of important
modification in the ceratodontid line is in the Triassic. This may,

OLSON: FAUNA OF UPPER VALE AND CHOZA 123

of course, be due to the scantness of the record, for no skulls or
teeth that can be referred with certainty to this line are known in
the Paleozoic. Romer and Smith (1934), it is true, have noted teeth
with a Ceratodus-like pattern from the Carboniferous and it is
possible that these specimens actually represent ancestral forms.
None are known from the Early Permian, however. If the negative
evidence of the lack of ancestral lepidosirenids in the Mesozoic is
to be considered an important item in the suggested derivation of
the lepidosirenids from the ceratodonts, some consideration must
be given to the fact that no protoceratodonts occur in the Permian
and no Sagenodus types have been found above beds of Wichita
age, although dipnoans of the Gnathorhiza type have now proven
to be abundant in the Vale of Clear Fork age. By application of
the same sort of evidence and the same type of reasoning as used
in the case for relationship of the ceratodontids and lepidosirenids,
it might be concluded that Gnathorhiza, not an impossible ancestor
for Ceratodus morphologically, is to be considered ancestral to both
the ceratodont and lepidosirenid lines.

Phyletic inter-relationships appear to be highly complex as a
result of the tendency for independent developments of similar modi-
fications in related lines. It seems equally possible from the mor-
phological standpoint for the lepidosirenids to have arisen from
either the Gnathorhiza stock or from the ceratodontid stock, and it
is not impossible, although the dentition may make it improbable,
that the ceratodontid stock might have arisen from Gnathorhiza.
Thus, as things now stand, the morphological evidence must be
considered as inadequate to solve the problem of relationships.

The stratigraphic evidence is of little more help. Great gaps in
the paleontological record have existed in the past. Some have
been filled while others still remain. Some, such as the lack of
evidence of coelacanth fish in the Tertiary, are explainable on environ-
mental bases; others, such as the lack of late Paleozoic, Mesozoic
and Cenozoic ancestors for the lampreys and hagfish, can be explained
by the absence of hard parts; still others, such as the absence of
known ancestors for the Chelonia of the Triassic, have, at present,
no explanation that is not purely conjectural. It thus becomes very
unsafe to assume that the lack of evidence of lepidosirenids in the
Mesozoic is strong evidence that they did not come into existence
prior to the late Mesozoic and thus must have been derived from the
ceratodontids. Perhaps, if such Mesozoic ancestors existed, they
lived under circumstances where preservation was improbable;

124 FIELDIANA: GEOLOGY, VOLUME 10

perhaps their range was restricted, as in the case of the two genera
of today. Any one of many explanations might be possible.

Every argument that may be advanced can be countered by one
equally plausible and we are forced, if we wish to classify, to use a
classification that has no sound basis of phylogenetic probability.
Such a classification, then, must be a categorization that is arbitrary
and practical, that introduces as little confusion as possible into
nomenclature, and that impedes and restricts our patterns of thought
no more than is necessary. Of the several possibilities in the present
situation, each may do violence to actuality. It seems more practical
at present to include Gnathorhiza with the forms that it resembles
most closely, as a genus under the Family Lepidosirenidae, than to
erect a new family for it, which would be necessary under any
other scheme.

5. AN ERYOPID AMPHIBIAN

GENERAL CONSIDERATIONS

One moderately well-preserved skull, a small part of the sculp-
tured dorsal surface of another skull, and a few skull roof fragments,
of uncertain affinities, are the only remains of large, labyrinthodont
amphibians that have been found to date in the upper beds of the
Vale. The first two may definitely be assigned to the genus Eryops.
It was reported earlier (1948) that this genus had not been dis-
covered in two seasons of collecting and that the failure to find any
traces of such a large animal might indicate that it did not exist
in the vicinity during the time of deposition of the beds. This,
of course, is now known to be incorrect, but the absence of limb
bones, vertebrae and other skeletal parts from the channel deposits,
which carry most of the specimens in the area, has yet to be explained.
Although the fragment of sculptured dorsal surface of the skull was
found in a channel conglomerate, it was not until production was
obtained from clay deposits that any well-preserved remains were
obtained.

Only the skull, C.N.H.M.-U.R. 23, is preserved well enough to
permit specific identification. This skull, although fractured into
a mosaic of small bone fragments, has preserved the original shape
with but little crushing. No sutures can be distinguished. It was
found with the palatal surface exposed and the lower jaws and ventral
margins of the skull were somewhat damaged by weathering. Only
the dorsal surface has been prepared, since this is sufficient for
identification and the skull was too fragile for further preparation.

OLSON: FAUNA OF UPPER VALE AND CHOZA 125

SPECIFIC ASSIGNMENT

The skull resembles that of the type of Eryops megacephalus
Cope in virtually all features that can be studied, except that it is
somewhat smaller. Measurements are given in Table 3 along with
measurements of the type (taken from Case, 1911). The difference
in size and slight differences in proportions cannot be considered
significant taxonomically, for a much greater range of variation is
seen among specimens of this species from earlier Permian beds.
The exact horizon from which the type of E. megacephalus came
is not known, but quite certainly the species occurs throughout much
of the Wichita and in the Clyde, Arroyo and Vale Formations of the
Clear Fork. The species persisted over a relatively long period of
time, longer, apparently, than did most species of Early Permian
tetrapods.

OCCURRENCE AND FAUNAL RELATIONSHIPS OF
ERYOPS IN THE VALE

Until 1948, vertebrates of late Vale age were known only from
beds of moderate to coarse conglomerates that originated as stream
deposits. During 1948, however, several occurrences in fine, green
channel sediments, red channel sands and clays of non-channel origin
were discovered. Two localities in the Vale and one in the Choza
where production may be obtained from clays are now known, as
follows:

1. "Clay Hill" in KH at CGV 4 41, 2.6-3.3, Vale.

2. "Chocolate Clay Locality" in KH at CGV 5 26, 6.3-4.95,

Vale.

3. Locality FA,1 Choza.

The skull of Eryops megacephalus, C.N.H.M.-U.R. 23, was found
at the first listed locality. The layer in which it occurred is exposed
around the margin of Clay Hill, a rounded prominence about 40
feet high and 150 feet in diameter, about 15 feet above the base of
the hill. The northern and western exposures of the bed consist
of about six feet of sandy, purplish-red clay. They grade into a more

1 See Olson, 1948, for index system. Locality FA was discovered and explored
in 1948-1950. It lies just north of the North Fork of the Wichita River in Foard
County, Texas, approximately north of Vera, Texas. It is shown on aerial photo-
graph CZW 1C 59 and has irregular boundaries that may be limited as follows:
NE corner at 1.3-3.9, N 60° E to 3.5-3.3, along margin of exposures to 3.7-2.4,
thence to 4.95-3.2, and SE and SW along margin of exposures to corner on river
at 4.3-1.5, W and slightly N along margin of open breaks to tank at 1.6-2.75,
along margin of exposures to NE corner of area.

126 FIELDIANA: GEOLOGY, VOLUME 10

sandy, somewhat thicker phase exposed at the southern margin of
the hill. This extremity contains layers and lenses of fine conglom-
erate. Much of the clay is rich in compressed plant remains, which
impart the purplish cast to the rock and give it a finely laminated
appearance. The clay deposit does not occur in the adjacent hills
to the north, east or west, but is continued in a sandy, conglomeratic
phase in a hill about fifty yards to the south of Clay Hill. This
deposit in turn is continuous to the south with a conglomerate
formed in a stream channel. It appears that the clay was laid
down in a pond of no more than a hundred yards in diameter with
an inlet to the south. Overlying the clay bed are deposits of clay
and sandstone capped by a conglomerate. All of these appear to
be of flood-plain origin.

In addition to the skull of Eryops, fragments of small amphibians,
two sets of vertebral spines of small dimetrodonts, jaws of Trimero-
rhachis, and many teeth and pieces of calcified cartilage of xenacanth
sharks have been found in the clay. This assemblage, except for
the dimetrodonts, which quite certainly came to the ponds for
watering or, perhaps, feeding, may well typify the life assemblage
that was characteristic of open and moderately persistent ponds of
the time. A deposit very similar to the one described above, so far
as the physical constituents are concerned, was found in locality
FA, but no plant or vertebrate assemblage was found in it.

It is possibly significant that Eryops, except for fragments, has
not been found in the many channel deposits that have been studied.
It may have been restricted in habitat to ponds and absent from the
streams and stream margins. The absence of Diplocaulus in fine-
grained deposits, in which its presence has not been noted, may also
be noteworthy in suggesting that this aquatic amphibian, abundant
where it does occur, existed in late Vale times in running water
only and was not associated with Eryops. This is in marked contrast
to the conditions in the Arroyo, in which D. magnicornis was pre-
dominantly a pond dweller and in which association with Eryops
is not infrequent. In this regard, it is of interest to note that one
fair specimen and several fragments of Diplocaulus were found in
the sandy-conglomeratic phase of the deposit in the exposures to
the south of Clay Hill. It is inevitable that such suggestions con-
cerning ecological relationships in part depend upon the fragile
web of negative evidence. Through many such analyses, correcting
misinterpretations as more evidence appears, we may hope eventu-
ally, however, to obtain a reasonably clear idea of environmental

OLSON: FAUNA OF UPPER VALE AND CHOZA 127

conditions and faunal and floral relationships and associations
throughout short spans of time even in periods as remote as the
Permian.

Table 3 —MEASUREMENTS OF ERYOPS MEGACEPHALUS
(In millimeters)

Specimen Ski (g)1 Ski (to) Skw (dp) low Orw Orl

A.M.N.H. 4189 433 335 118 86 57 48

(type)
C.N.H.M.-U.R. 23 360 310 120 60 55 55

(Vale)

1 Abbreviations: Skl(g), greatest skull length, snout to level of posterior
termination of quadrate; Skl(m), skull length along dorsal midline; Skw(dp),
skull width at posterior end of dorsal platform; low, interorbital width, minimum;
Orw, orbital width, maximum normal to midline; Orl, orbital length, maximum
parallel to midline.

ADDENDUM

As the result of unexpected delay in publication of this series
of papers, certain family, generic and specific names established
herein inadvertently appeared in an earlier paper (Olson, E. C.
1951, Vertebrates from the Choza Formation, Permian of Texas.
Jour. Geol., 59, pp. 178-181). The names are as follows: Family
Waggoneridae, genus and species Waggoneria knoxensis, species
Gnathorhiza dikeloda.

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Bridge, T. W.
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Dollo, L.

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HUSSAKOF, L.

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