THE AISTOPODOUS MICROSAURIAN FAMILY PTYONIIDÆ, FROM THE COAL MEASURES OF
OHIO.
=Family PTYONIIDÆ Cope, 1875.=
Cope, Geol. Surv. Ohio, II, pt. II, p. 357, 1875.
Elongate, slender, weak-limbed, aquatic microsaurians. Neural and
hæmal spines of vertebræ elongated, expanded and sculptured. Ventral
armature weakly developed or absent. Skull lanceolate, with long,
slender teeth.
Three genera are assigned to this family: _Ptyonius_, _Œstocephalus_, and
_Thyrsidium_. The forms are very closely related, and when additional
material is secured the three genera may be found to be identical. The
species included in this family are: _Ptyonius pectinatus_ Cope, _P.
vinchellianus_ Cope, _P. marshii_ Cope, _P. nummifer_ Cope, _P. serrula_
Cope, _Œstocephalus remex_ Cope, _O. rectidens_ Cope, _Thyrsidium
fasciculare_ Cope. The species are all exclusively from the Linton, Ohio,
Coal Measures, and most of them are known from abundant material.
=Genus PTYONIUS Cope, 1875.=
Cope, Geol. Surv. Ohio, II, pt. II, p. 373, 1875.
Cope designated no species as the type, but we may regard _Ptyonius
pectinatus_ as typical.
Form elongate, with long tail and lanceolate cranium. Limbs weak, a
posterior pair only discovered. Three clavicular elements; abdomen
protected by packed osseous rods, which are arranged _en chevron_, the
angle directed forward. Neural and hæmal spines of caudal vertebræ
expanded and fan-like. Ribs well developed. The various species vary in
length from 3 to 10 inches. They are the most abundant amphibian in the
Linton beds. The present genus resembles _Lepterpeton_ Huxley (334), of
the Kilkenny, Ireland, Coal Measures. But that genus possesses divided
abdominal rods, or "oat-shaped scales," and the form of the cranium and
proportions of the body are different.
The genus is closely related to, possibly identical with, _Œstocephalus_,
but additional material will be required to settle this point.
Cope (123) gives the following key for the separation of the 5 species:
x. Abdominal rods coarser, not more than 10 in 5 mm.
Median pectoral shield discoid, radiate-ridged;
muzzle short _P. nummifer_
Median pectoral shield oval, pitted and ridged _P. marshii_
xx. Abdominal rods hair-like, 15 or more in 5 mm.
Median pectoral shield with radii from the center,
the principal forming a cross; form wider _P. vinchellianus_
Middle pectoral with pits at the center and few or
no radii; form narrow _P. pectinatus_
Middle pectoral shield narrow, closely reticulate
medially, and radiate towards the circumference;
size half that of last _P. serrula_
=Ptyonius pectinatus Cope.=
Cope, Proc. Acad. Nat. Sci., 1868, p. 216.
Cope, Trans. Am. Phil. Soc., XIV, p. 20, 1869.
Cope, Trans. Am. Phil. Soc., XV, p. 266, 1874.
Cope, Geol. Surv. Ohio, II, pt. II, p. 377, pl. xxvii, fig. 7; xxviii,
figs. 2, 3, 6; pl. xxix, fig. 2; pl. xxx, fig. 2; pl. xxxv, figs. 1-3;
pl. xli, fig. 1, 1875.
Moodie, Proc. U. S. Nat. Mus., 37, p. 24, pl. 8, fig. 3, 1909.
Schwarz, Beiträge zur Paleontologie und Geologie Osterreich-Ungarns
und des Orients, Bd. XXI, p. 83, figs. 23, 24, 26, 1908.
Type: It is impossible to determine which one of the specimens is the
type. There are numerous representatives of the species, as follows: Nos.
140, 1096 G, 8345 G, 8555 G, 1089 G, 2, 132, 133, no number, 1094 G, 8545
G, 8677 G, 1159 G, 105, no number, 1091 G, 7_a_, 1092 G, 1093 G, 1095 G,
153, and others unnumbered in the American Museum of Natural History; in
the U. S. National Museum are the following: Nos. 4458, 4463, 4464, 4514.
(Plate 20, fig. 2.)
Horizon and locality: Linton, Ohio, Coal Measures.
The most abundant species of the Linton Coal Measures. There are over
three dozen specimens preserved in the Newberry collection. The species is
a clearly marked one, as a rule, though there is great variation in the
size of the body and the form of the vertebræ. Though there are several
apparently complete skulls preserved in the collection, it is impossible
to make out the morphology of the elements on account of the amount of
crushing to which the skulls have been subjected.
[Illustration: Fig. 30. Restoration of _Ptyonius_. × 1.]
The head is lancet-shaped, and the muzzle very elongate, slender, and
acute at the extremity. The head is in fact a miniature of an ichthyosaur
cranium. (Plate 20, fig. 2.) The orbits are large and posterior to the
median line. The anterior portion of the skull is narrow, posteriorly
truncate, and the mandibular angle is projecting. The posterior portion
of the mandible is sculptured. Possibly the entire cranium was also, and
this has been lost; in fact, this sculpturing is indicated in one or two
specimens. The teeth are conical and sharp, longitudinally striate, and
anisodont. There seems to be evidence of palatine or pterygoid teeth,
though this needs confirmation. The pectoral plates are well preserved,
with the interclavicle a narrow oval, with anterior and posterior
prolongations. In one specimen it is sculptured. The clavicles are narrow
and slightly sculptured. The abdominal scutellæ are bristle-like.
The vertebræ are short, with expanded neural and hæmal spines. The
expanded condition of the neural spines begins over the thoracic region,
where they are low. They become well developed in the posterior dorsal
region. The caudal fan-shaped spines are larger. The dilated portions
form equilateral triangles which stand on moderately short pedicels. They
are weakly ridged, and each ridge is prolonged into a narrow acute tooth
beyond the margin, 11 of which may be counted on one of the best preserved
spines. The longitudinal striæ are terminated near the pedicel by two
others which cross obliquely from each side, and, meeting, present the
appearance of the margin of a cup sculptured in relief, from which the
striæ arise. Pedicels smooth. The spines are in contact at their angles,
thus forming a continuous line. In a typical specimen there are 6 in half
an inch, in another 7, and in a third 8. The ribs are well-developed and
slender.
No traces of fore limbs have been detected in the numerous specimens, but
elements of hind limbs are preserved. In one of these the femur is a small
bone, contracted at the middle. The form of the body is snake-like.
There were probably from 75 to 100 vertebræ in a single animal. The form
may be well compared to the modern _Amphiuma_ so far as appearances are
concerned; structurally they are widely separate. This species is one
which is peculiarly characteristic of the Linton fauna.
Measurements of Ptyonius pectinatus Cope.
_Nos. 107 and 1094 G, American Museum._
mm.
Length of specimen 137
Length of skull 26
Posterior width of skull 8
Interorbital width 3
Diameter of orbit 1.5
Vertical expanse of vertebra 6
Width of neural fan 2
Diameter of pedicel 1
_Measurements of a small jaw, No. 8555 G, American Museum._
mm.
Length of jaw 15
Greatest width 1.5
Length of tooth 1
_Measurements of specimen No. 4438, U. S. National Museum._
mm.
Length of specimen 65
Length of skull 22
Width of skull 6
=Ptyonius vinchellianus Cope.=
Cope, Proc. Am. Phil. Soc., p. 177, 1871.
Cope, Geol. Surv. Ohio, II, pt. II, p. 376, pl. xxviii, fig. 1, 1875.
Type: Specimen in the American Museum of Natural History.
Horizon and locality: Linton, Ohio, Coal Measures.
The species is represented by the opposite halves of a single specimen,
which includes only the cranium and anterior half of the body. The
fan-shaped neural spines commence but a short distance behind the line
of the pectoral shields. They are low, with a few coarse ridges, the
margin being entire. The abdominal rods are delicate and hair-like. The
interclavicle is oval, with a few radiating crests, which originate at
the center; in the areas behind there are a few scattered tubercles. The
clavicles are ridged near the margin.
The cranium is lanceolate in form, and the bones of the dorsum are marked
with a few raised points and ridges. The species is about the size of
_Ptyonius pectinatus_ Cope, and differs, apparently, from that species in
the rather insignificant character of a narrower interclavicle and in the
ornamentation of the same. Dedicated to Professor Alexander Winchell, of
the University of Michigan.
Measurements of Ptyonius vinchellianus Cope.
mm.
Length of cranium 20
Width of same 8
Length of interclavicle 4-2
=Ptyonius marshii Cope.=
Cope, Trans. Amer. Phil. Soc., XIV, p. 24, 1869 (_Colosteus marshii_).
Cope, Geol. Surv. Ohio, II, pt. II, p. 375, pl. xxvii, fig. 6; pl.
xxviii, fig. 3, 1875.
Cope, Proc. Am. Phil. Soc., XII, p. 177, 1871.
Type: Specimen No. 1157 G, American Museum of Natural History.
Horizon and locality: Linton, Ohio, Coal Measures.
The head is elongate lanceolate. The upper surface of the frontal bones is
punctate-rugose in relief, with short radii toward the margin. The distal
two-thirds of the mandible is narrow wedge-shaped; the external surface
is coarsely pitted. There are no teeth preserved. The pectoral elements
are displaced, but the clavicles are subtriangular, and are strongly
ridged toward the inner margin. The interclavicle is short spatulate, the
narrow portion directed anteriorly; the posterior rounded. It is coarsely
pitted medially, and coarsely and strongly radiate-ridged to the margin.
The abdominal armature commences immediately behind the pectoral girdle.
It consists of elongate, narrow, subcylindric scales, which meet on the
median line, converging anteriorly. Small limbs are present.
Measurements of Ptyonius marshii Cope.
Type specimen: mm.
Length of fragmentary skull 7
Width of skull as preserved 5
Length of entire specimen 68
Width across pectoral plates 8
Width across belly 7
Specimen No. 1098 G, American Museum:
Length of specimen 32
Width of specimen 7
4 scutes of abdominal armature in 1 mm.
=Ptyonius nummifer Cope.=
Cope, Geol. Surv. Ohio, II, pt. II, pp. 374, 375, pl. xli, figs. 2 and
3, 1875.
Moodie, Bull. Am. Mus. Nat. Hist., XXVI, p. 356, pl. 63, fig. 3, 1909.
Type: Specimen No. 8546 G, American Museum of Natural History. No. 8614 G,
same museum, is associated with the type specimen.
Horizon and locality: Linton, Ohio, Coal Measures.
Two well-preserved individuals display peculiarities which indicate
specific distinctness from the previously known species of _Ptyonius_.
The abdominal rods are of the coarse type of those of _P. marshii_. The
caudal fans are well developed, and not so wide as in _P. pectinatus_.
The interclavicle is a discoid body of different form from that of _P.
marshii_ and I can not detect the clavicles. The sculpture consists
of strong ridges, which radiate from the center to near the border.
Immediately in front of this interclavicle is the head, which has a
different form from that of the other known species. The interorbital
width is two-thirds the long diameter of the orbit. The structure of the
skull can not be made out. A slender, elongate hind limb is present in the
second specimen, and a humerus is well preserved in the type.
Measurements of the Type of Ptyonius nummifer Cope.
(No. 8546 G, American Museum of Natural History. No. 8614 G is associated
in the same species.)
mm.
Length to beginning of caudal fans 65
Length of head 15
Length from muzzle to orbits 6
Length of interclavicle 7
Width of interclavicle 8
Width of abdominal armature 8
Length of a caudal fan 2.5
Length of femur 5
Proximal width of femur 1.5
=Ptyonius serrula Cope.=
Cope, Proc. Am. Phil. Soc., 1871, p. 177.
Cope, Geol. Surv. Ohio, II, pt. II, p. 379, pl. xxviii, fig. 5; pl.
xxx, fig. 1, 1875.
Type: Specimen No. 8615 G, American Museum of Natural History.
Horizon and locality: Linton, Ohio, Coal Measures.
The specimens of this species indicate that the form was only about half
the size of _Ptyonius pectinatus_. The interclavicle is narrower and more
reticulately sculptured. The tail is relatively longer. Abdominal rods
hair-like. Ribs distinct. Small limbs are present in one specimen.
Measurements of Cope's Type of Ptyonius serrula.
mm.
Length of specimen 95
Length of portion of skull preserved 3
Length of interclavicle 4.5
Width of interclavicle 2
Length of clavicle 4
Width of clavicle 1.5
Length of vertebra 1
Width of vertebra from tip of neural
spine to tip of hæmal spine 4
Another specimen (456 G, American Museum of Natural History) shows some
of the same characters. There is not the slightest basis for the support
of this species, so far as I can observe. The ones mentioned by Cope are
insufficient. It is in all probability a mutant or variety of _Ptyonius
pectinatus_.
=Genus ŒSTOCEPHALUS Cope, 1868.=
Cope, Proc. Phila. Acad. Nat. Sci., 218, 1868.
Cope, Trans. Amer. Phil. Soc., XIV, 16.
Cope, Proc. Phila. Acad. Nat. Sci., 1868, 217.
Cope, Proc. Amer. Phil. Soc., 1871, 41.
Cope, Geol. Survey Ohio, II, pt. II, 380, 1875.
Type: _Œstocephalus remex_ Cope.
Form slender and snake-like; caudal vertebræ with elongated, dilated,
sculptured neural and hæmal spines. Cranium lanceolate. Teeth numerous,
of nearly equal size. No pectoral shields known; abdomen protected by
very numerous bristle-like rods, which converge forwards. A pair of weak
posterior limbs; branchihyal bones present.
In the only well-preserved species the cranial bones exhibit no sculpture
from the parietal region forward. The genus is not very distinct from
Ptyonius, but it can not be united with that genus until more complete
material is available. The species of the genus share with _Ceraterpeton_,
_Urocordylus_ (334), and _Ptyonius_, as well as _Crossotelos_ (98), from
the Permian of Oklahoma, the elongation, sculpture, and expansion of the
neural and hæmal spines. There are but 2 species, which Cope distinguishes
by the following characters:
I. Vertebræ elongate; fan-like caudal processes narrowed. Size
large; mandibular teeth of unequal lengths, with the apices
turned backward _Œstocephalus remex_
II. Species only known from cranial bones with teeth. Teeth equal,
erect, with acute conic apices, 11 in 5 mm _Œstocephalus rectidens_
=Œstocephalus remex Cope.=
Cope, Proc. Phila. Acad. Nat. Sci., p. 217, 1868 (_Sauropleura remex_).
Cope, Proc. Phila. Acad. Nat. Sci., p. 218, 1868 (_Œstocephalus
amphiumianus_).
Cope, Trans. Amer. Phil. Soc., XIV, p. 17.
Cope, Geol. Surv. Ohio, vol. II, pt. II, p. 381, pl. xxvii, fig. 5;
pl. xxxi, fig. 1; pl. xxxii, fig. 1; pl. xxxiii, fig. 2; pl. xxxiv.
fig. 4, 1875.
Moodie, Proc. U. S. Nat. Mus., 37, p. 27, 1909.
Type: Specimen undetermined. The following specimens are to be found:
Specimens of _Œstocephalus remex_ Cope in the National Museum, Nos.
4511, 4460, 44/8. There is one specimen of _Œstocephalus remex_ in the
University of Chicago. Specimens of the species in the American Museum of
Natural History: Nos. 121, 8322 G, 8694 G, no number, 8656 G, 8583 G, 8659
G, 19, 120, 8655 G, 8662 G, 8708 G, 8665 G, 112, 8663 G, 8581 G, 8658 G,
8660 G, 8700 G, 8469 G, 1102 G, 1152 G 142, 8381 G, and obverse, 21, 8664
G, 8672 G, 8592 G, 8684 G.
Horizon and locality: Linton, Ohio, Coal Measures.
This species is one of the most abundant of the Linton Amphibia. Cope
based his description of the species on 9 specimens. There are more than
two dozen available at the present time, the majority of them being in the
possession of the American Museum of Natural History. There is a single
specimen in Walker Museum of the University of Chicago and 3 in the United
States National Museum. The numbers of all of these specimens are given
above. The material consists, for the most part, of fragmentary portions
of the vertebral column, but there are a few skulls more or less complete,
though none are sufficiently well preserved for a complete analysis of the
characters. The specimens indicate an animal slightly smaller than the
modern _Amphiuma_ means of the Mississippi River.
[Illustration: Fig. 31. Restoration of _Œstocephalus_. × 1.]
It will not be necessary here to enter into a detailed account of each
specimen, since this has been done by Cope, and a careful comparison of
his descriptions with the originals indicates that his observations are
correct. The species, as suggested in the discussion of the genus, is
not clearly distinct from those of _Ptyonius_, and it has largely the
characters of that genus. The cranium is long, slender, and wedge-shaped.
The teeth are numerous both in the maxillary and in the mandible, one
specimen indicating about 30 in a single series. They are all uniformly
cylindrical, except at the extremity, where they are flattened and
expanded so as to produce a longitudinal edge, which is carried backward
on a recurvature of the apex. The bases are anchylosed equally and without
enlargement, and no part of the shaft is striate or grooved. The upper
surface of the cranium is narrow, with the median suture distinct. The
skull surface, with that of the mandible, is smooth.
Characteristic of the species are the remarkable length and slenderness
of the fan-shaped neural and hæmal spines, and the absence of an acute
serration on their margins. In this species the spines have a laminiform
expansion at the base in their plane. One specimen exhibits the pelvic
region, including a portion of the tail. The ilium has an expanded
anterior extremity and is directed backwards and somewhat inwards on
either side of the vertebral column. The femur is nearly straight, short,
contracted medially, and expanded distally. The tibia is shorter and is
subcylindrical. Beneath the ilium the last chevron of the abdominal rods
appears, the outer extremities rising on the base of the tail.
The pectoral arch is almost unknown, and Cope based the distinction of
_Ptyonius_, and _Œstocephalus_ on the absence of these plates in the
latter genus an uncertain characterization. The fore limbs are indicated
by a humerus. There were possibly from 75 to 100 vertebræ in the entire
column. The animal was exclusively adapted to life in the water and was,
without doubt, an excellent swimmer. There are preserved in one specimen
portions of what seem to be hyobranchial elements.
Measurements of Œstocephalus remex Cope.
mm.
Length of entire caudal series 195
Width at ninth vertebra 21
Width at thirty-sixth vertebra 2
Length of four phalanges in place 14
Expanse of fan of proximal caudal 18.5
Length of ilium 11.5
Length of femur 11.5
Length of tibia 7
Length of mandibular dental series 24
Depth of mandible at middle 5
Nine teeth in 5
Length of longer teeth 2
Length of first hæmal branchial 6
Length of sixth vertebra from skull 7
Width of centrum 3
=Œstocephalus rectidens Cope.=
Cope, Trans. Amer. Phil. Soc., p. 268, Apr., 1874.
Cope, Geol. Surv. Ohio, II, pt. II, p. 386, pl. xxvii, fig. 3, 1875.
Type: Specimen No. 9033, American Museum of Natural History, collection of
J. S. Newberry.
Horizon and locality: Linton, Ohio, Coal Measures.
The species is indicated by a left dentary bone, with its teeth and
external surface preserved. The latter is nearly smooth and without
sculpture. The outer face is convex, and the general form is slender, but
not curved upward at the extremity. The extremity of the dentary does
not show any evidences of teeth. Teeth straight and conic, apex acute,
non-plicated.
Cope also associated with this species a portion of a caudal series,
consisting of 25 vertebræ. The centra are elongate and expanded at the
extremities. The neural arches have a close union. The neural and hæmal
spines are fan-shaped and striated. The bases are quite narrow.
Measurements of Œstocephalus rectidens Cope.
mm.
Length of dentary 22
Length of tooth line 15.2
Depth of dentary at last tooth 2.7
Length of 3 centra of the caudal series 8.6
Extent of neural and hæmal spines 8.7
=Genus THYRSIDIUM Cope, 1875.=
Cope, Geol. Surv. Ohio, II, pt. II, p. 365, pl. xxxi, fig. 2, 1875.
Type: _Thyrsidium fasciculare_ Cope.
Established on a species which presents its principal peculiarities in the
structure of the vertebræ. Two specimens present inferior views of the
spinal column, showing that the genus possesses, like _Siren_, enlarged
diapophyses, but they are peculiar in their fan-like form. They resemble
slightly the neural spines of the caudals of _Ptyonius_, but are present
on the dorsal vertebræ. Whether the caudals of the present species possess
ornamented neural spines the specimens do not indicate. The abdomen is
protected by the usual hair-like rods arranged _en chevron_, the angle
directed forwards. No indications of limbs can be discovered on the
blocks.
Without the cranial bones the affinities of this genus can not be
determined; while it may be allied to _Cocytinus_, the vertebræ of that
form are without peculiar diapophyses.
=Thyrsidium fasciculare Cope.=
Cope, Geol. Surv. Ohio, II, pt. II, p. 365, pl. xxxi, fig. 2, 1875.
Type: Specimen No. 8552 G, American Museum of Natural History.
Horizon and locality: Linton, Ohio, Coal Measures.
The best preserved example of this species includes 9 vertebræ and the
corresponding ventral armature. The centra, seen from below, are much
contracted in their form, presenting an obtuse median rib, which expands
to the articular extremities. In one or two instances the latter are
divided by fracture, and the moderately concave form of the adjacent
surfaces is displayed. The diapophyses are of complex form, but the
details are concealed by the prevalent thin layer of coal which invests
them. An inferior prominence runs parallel to the centrum; outside of this
the process is obscurely trilobate and thickened, not flattened, as in the
caudal vertebræ of _Ptyonius_. Several ribs (fig. 8) of moderate thickness
appear by the side of the diapophyses. Eleven abdominal ribs in 5 mm.
The second specimen was originally referred to _Œstocephalus remex_, as
a posterior portion of its vertebral column, immediately preceding the
caudal series.
This reference appears to be incorrect, although the resemblance between
the corresponding parts in the two genera is no doubt considerable, and
the alternative of proposing a new genus and species was not at that time
advisable.
The neural spines are longer than high, and are nearly in contact at their
margins; each is marked by about 5 obtuse vertical ribs. A fractured
section of the abdominal spines in place displayed at least six layers of
them.
The material on which the above account is based is imperfect. The
specimen figured by Cope (Geol. Surv. Ohio, vol. II, pt. II, pl. xxxi,
fig. 2, 1875) is undoubtedly a portion of the vertebral column of
_Œstocephalus remex_. Nos. 4462 and 4480 of the United States National
Museum may be representatives of _Thyrsidium fasciculare_, but they are
more probably _Œstocephalus remex_; if they are the latter this leaves the
type as the only known specimen of the species.
Measurements of Type of Thyrsidium fasciculare Cope.
mm.
Length of portion of vertebral column preserved 7
Width of ventral armature 18
Length of a vertebra 9
Width of same vertebra 4