  THE MICROSAURIAN FAMILY MOLGOPHIDÆ, FROM THE COAL MEASURES OF OHIO AND MAZON CREEK, ILLINOIS. Family MOLGOPHIDÆ Cope, 1875. Cope, Geol. Surv. Ohio, II, pt. II, p. 157, 1875. Cope, Bull. U. S. Nat. Mus., No. 1, p. II, 1875. Type of family: Molgophis. Body long, serpentine, a few species apparently limbless, ribless, and with abdominal armature lacking. VertebrÆ elongate, neural and hÆmal spines short or absent. Ribs long, heavy, and broad. The vertebrÆ seem to bear the characteristic marks of the family. One species has the skeleton reduced to a lanceolate skull and a string of about 50 slender vertebrÆ, all the rest of the skeleton being absent. The family is very poorly known, but was apparently of wide distribution in North America and confined to this continent. The representatives of the group are known from Iowa, Illinois, and Ohio. Four genera are assigned to the family, but future discoveries will undoubtedly demand revision of the present classification. The genera are Molgophis, Pleuroptyx, Phlegethontia, and Erpetobrachium. The distinguishing characters of these genera are apparent from the descriptions of the various forms. The skeletons of the species are too incompletely known to allow the establishment of a tabular key to the genera. Cope, Proc. Phila. Acad. Nat. Sci., p. 220, 1868. Cope, Trans. Amer. Phil. Soc., XIV, p. 20, 1869. Cope, Geol. Surv. Ohio, II, pt. II, p. 368, 1875. Cope, Trans. Amer. Phil. Soc., XV, p. 263, 1874. Type: Molgophis macrurus Cope. Cope (123) gives the following: "The characters of this genus are: body long, serpentine, without dermal armature, so far as known; vertebrÆ long and broad, with very prominent zygapophyses and moderate neural spines; ribs large, curved. No limbs or cranium can be ascribed to the type of the genus. The ribs are long, and though the head is not bifurcate, there appears to be both tubercle and head on the dilated extremity. Where crushed they display a large median vacuity. "This genus differs from Ophiderpeton Huxley (334) in the characters of the dorsal vertebrÆ, which, in their projecting zygapophyses, resemble those of Amphiuma. The lack of ventral armature distinguishes it from Œstocephalus, while its well-developed ribs separate it from Phlegethontia." Molgophis macrurus Cope. Cope, Proc. Phila. Acad. Nat. Sci., p. 220, 1868. Wyman, Am. Jour. Sci. and Arts, p. II, fig. 1, 1858 (refers to a batrachian reptile). Cope. Trans. Amer. Phil. Soc., XIV, p. 20, 1869. Cope, Trans. Amer. Phil. Soc., XV, p. 263, 1874. Cope, Geol. Surv. Ohio, II, pt. II, p. 368, pl. xliii, fig. 1, 1875. Type: Specimen No. 8617 G, American Museum of Natural History, collection of Dr. J. S. Newberry. Horizon and locality: Linton, Ohio, Coal Measures. This species is established by remains of 2 individuals, one embracing 16 and the other 14 vertebrÆ, with ribs. The neural arches, viewed from above, have a V-shaped outline posteriorly, from the fact that the broad zygapophyses meet on the median line and spread out distally over the broad anterior ones adjoining. The latter appear to be somewhat concave and to border the former exteriorly as well as inferiorly. The base of the neural spine extends to the posterior emargination, but not quite to the anterior. The breadth of the dorsal vertebrÆ above is equal from the emargination behind to the anterior margin of the anterior zygapophyses. The ribs are long for an amphibian, but not long for a reptile. They are well curved, chiefly near the proximal extremity. The longest found, measured by a cord, equals two and two-fifths vertebrÆ. These vertebrÆ, measured along the median line above, equal 11 lines; one of these is 3.6 lines in width above. This animal has been, like Amphiuma, a snake-like amphibian, but was probably still larger. How near the affinities to this genus may be can not now be determined, owing to the want of many important parts of the skeleton, but it differs in the important feature of large, well-developed ribs. The size of the vertebrÆ would indicate a body of the size of the common rattlesnake (Crotalus horridus) and too large for Brachydectes newberryi, which is only known from jaws. Fig. 32.—Drawing from Cope's figure of Molgophis brevicostatus Cope, × 0.5 Molgophis brevicostatus Cope. Cope, Geol. Surv. Ohio, II, pt. II, p. 369, pl. xliv, fig. 1, 1875. Moodie, Proc. U. S. Nat. Mus., 37, p. 27, 1909. Type: Specimen No. 8341 G, Amer. Mus. of Nat. History. Horizon and locality: Linton, Ohio, Coal Measures. Represented by portions of the vertebral column of several individuals. One of these includes 9 pairs of ribs, with vertebrÆ, and another 13 pairs. The vertebrÆ are subquadrate in section, and the concavity of the two articular faces is not deep. They support strong lateral ridges separated by deep concavities. The heads of the ribs are somewhat contracted, and the shafts present outward a tubercular angle at a distance of one-fourth the length from the head. The remaining part of the shaft is stout, nearly straight, and gradually contracts to an obtuse extremity. It possesses a narrow medullary cavity. In none of the specimens is there any trace of abdominal armature, but abundant remains of the contents of the abdominal cavity, in proper position, are preserved on the blocks. This species is more massive than Molgophis macrurus, and the ribs are shorter, thicker, and less curved. Ventral scutellÆ are present in one specimen of this species. There are a number of specimens. They have the following numbers at the American Museum: 158, 1100 G, no number, 8341 G (type), no number, 8466 G; and 4477 in the U. S. National Museum.
Molgophis wheatleyi Cope. Cope, Geol. Surv. Ohio, II, pt. II, pp. 369, 370, pl. xlv, fig. 1, 1875. Cope, Trans Am. Phil. Soc., XV, p. 263, 1874. Type: Specimen No. 1101 G, American Museum of Natural History. Horizon and locality: Linton, Ohio, Coal Measures. A critical study of the type specimen of this species does not reveal anything essentially different from the description of Cope. The following is taken from his report (123): "Established on a specimen which exhibits about twenty-five vertebrÆ with ribs, and the posterior portion of the cranium. No traces of abdominal scales or rods, thoracic shields, or limbs are visible. By such negative characters it is referable to the genus Molgophis, although the definition of this genus is incomplete. The present batrachian may, indeed, be ultimately found to be an Ophiderpeton, to which it also bears some resemblance. "The specimen is that of an animal of very much smaller size than the M. macrurus. The vertebrÆ are of moderate length, with a low neural spine, and centrum angular at the sides and truncate at the articular extremities when in place. The ribs are rather short, slightly curved, apparently hollow and intercentral in position. Although the vertebral centra are ossified, the elements of the cranium have a larval appearance. These consist of two parallel bony plates, which resemble the fronto-parietal bones of the frog; they are slightly separated from each other, but do not inclose a fontanelle. A wedge-shaped bone extends from the outside of the front of each of these, acuminate behind, and widening anteriorly in the position of a postfrontal bone. In front of the posterior border of each parietal, on its outer side, a bony enlargement arises which contracts outward and forward into a narrow element which curves forward beneath the postfrontal. These look like an anteriorly directed quadrate with articular bone, such as seen in the larvÆ and some adults of existing batrachians. These determinations will require confirmation from additional material. In the meantime it is evident that the present specimen can not be referred to any of the other species herein described. The elements of the cranium are entirely smooth with no sign of sculpture, and in this respect the present species is unlike any of the other known from the Carboniferous." The vertebrÆ are not so clearly marked as one is led to believe from Cope's figure.
The species is dedicated to Charles M. Wheatley, of Phoenixville, Pennsylvania, one of the original investigators of the Linton deposits. It is a part of the Newberry Collection. Additional material of this species is represented by specimens Nos. 7 and 8699 G of the American Museum of Natural History. They are both very unsatisfactory. They consist of molds of the vertebral column, with in one case an enlargement at one end which may represent the head, and if such, the specimen probably represents a distinct species. The impression, No. 7, contains molds of about 30 vertebrÆ The other impression, 8699 G, contains impressions of about 20 vertebrÆ, apparently immature, though one can not be entirely sure as to the nature of the structures. They are covered over with a thin layer of carbonaceous material which is impossible to remove satisfactorily. The two specimens remind one of what Huxley has written in regard to the forms of Microsauria (334) from Kilkenny, Ireland.
Moodie, Kans. Univ. Sci. Bull., VI, No. 2, p. 353, 1912. Type: Erpetobrachium mazonensis Moodie. The generic characters are apparent in the greatly elongated fore limb, in the exceptionally broad scapula, the long radius and ulna, which slightly exceed the humerus in length, a character hitherto unknown among Carboniferous Amphibia. Erpetobrachium mazonensis Moodie. Moodie, Kans. Univ. Sci. Bull., VI, No. 2, pp. 353-354, pl. 2, fig. 2; pl. 8, fig. 3, 1912. Type: Specimen No. 799 (222), Yale University Museum. Horizon and locality: Mazon Creek shales, near Morris, Illinois. The scapula of the present form is exceptional in its shape. It resembles an asymmetrical pyramid, the anterior side of the lower edge of the bone being contracted so that the anterior edge of the element is arcuate. Its top is very thin and possibly terminated in a broad cartilage. The lower end is thick and heavy and the articular surface is, apparently, well formed, though somewhat obscured. The element identified as a clavicle is lying on its edge and has the proportions of the clavicle of Mazonerpeton costatum. The exterior edge is somewhat rounded and small. A portion of another element which I suppose to represent the coracoid lies alongside the humerus, although its form is quite obscured. (Plate 3, fig. 3.) The humerus has a remarkably well-formed head. In perfection of formation it corresponds well with that of the higher reptiles. This surface can even be divided into an anterior and a posterior articulation. The element projects posteriorly for the distance of 1 mm. from the surface of the shaft. The shaft immediately below the head is somewhat flattened and has an ovoid section. Further on it becomes flattened, a part of which is probably due to pressure during fossilization. The elements of the forearm are both preserved and are approximately equal in size. They are remarkable in that they exceed the humerus in length, although they are not so heavy as that element. They are greatly elongate and slender, with the middle of the shaft only moderately contracted. The articular surfaces are well formed and both bones were hollow, as was also, apparently, the humerus. The ulna may be represented by the most posterior of the two elements, though the relations of the elements may have been reversed (fig. 15, D). The base of the left wing of an orthopterous insect possibly allied to Paolia gurleyi Scudder lies between the radius and ulna. The nodule also contains impressions of plants, a portion of a frond of a Neuropteris and the impression of one of the Cordaites. Lying next the radius is a slender elongate element which may be a rib or a portion of a metacarpal. If a rib, it indicates that the animal belongs among the Branchiosauria. The fragment is only half as long as the radius and is entirely too obscure to base any conclusions. The other characters of the specimen point quite strongly to its microsaurian affinities. The structure of the articular surfaces of the limb bones alone would indicate the microsaurian relationship of Erpetobrachium. It may be provisionally associated in the family MolgophidÆ with such forms as Molgophis brevicostatus Cope, Molgophis (Pleuroptyx) clavatus Cope, and Molgophis macrurus Cope from the Coal Measures of Linton, Ohio.
Cope, Geol. Surv. Ohio, II, pt. II, p. 370, pl. xlii, fig. 1; pl. xliv, fig. 2, 1875. Cope, Proc. Phila. Acad. Nat. Sci., p. 16, 1875. Moodie, Proc. U. S. Nat. Mus., 37, p. 27, 1909. Type: Pleuroptyx clavatus Cope. The specimens on which the species of this genus repose do not exhibit crania. The 5, probably 6, specimens which represent them offer various views of the vertebral column, and in none is there any trace of ventral or thoracic armature. Limbs can be ascribed to them with probability only. The vertebrÆ are of moderate length, with well-developed zygapophyses, and a short and not very elevated neural spine in the dorsal region, which is not sculptured in any way. The generic character is seen in the ribs. These are rather short and very stout and support an ala on the posterior or convex border, which expands downwards, and then suddenly contracts to the shaft. The extremity of the latter is broad and truncate, and includes a medullary cavity, which is only partially fitted with cancellated tissue. Pleuroptyx clavatus Cope. Cope, Geol. Surv. Ohio, II, pt. II, p. 370, pl. xlii, fig. 1; pl. xliv, fig. 2, 1875. Cope, Proc. Phila. Acad. Nat. Sci., p. 16. 1875. Moodie, Proc. U. S. Nat. Mus., 37, p. 27, 1909. Type: Specimen No. 8617 G, American Museum of Natural History. Horizon and locality: Linton, Ohio, Coal Measures. The general appearance of the species of Pleuroptyx is that of the Molgophis, so far as known, but nothing resembling the peculiar structure of the ribs is seen in any other. There is no assurance that the genus is distinct from Molgophis. Parts of two individuals express the typical characters of this species, while a third only differs in being considerably smaller. A fourth may very probably be referred here, and another, bearing several elements of a leg, should be most likely associated with the last mentioned. The ribs are considerably narrowed near the head, and appear to possess a low tubercular process some distance below it. The shaft is curved throughout; the laminar expansion is quite thin; while the distal end is expanded and concave, perhaps for the attachment of cartilage, although no trace of this remains on the shale. The neural spines have short bases, oblique anterior and nearly straight posterior borders, with obtuse extremity. I perceive no essential difference in the smaller specimen, which is one-third less than the types. The limb is appropriate in its proportions to the present species, and may be described in this place. The first segment is one-third longer than the second, and has a transversely expanded head. The shaft is stout, the distal extremity not expanded and concave. The second segment is stout, more expanded proximally than distally, the proximal end truncate and slightly concave. A bone, much displaced, lies near it, and is probably ulna or radius; it is as stout as the first, the end not expanded. Of metatarsals there are 2, three-fifths the length of the second bone of the leg, and of phalanges 2, of 2 digits each. The proximal are three-fourths the length of the metatarsals, and indicate elongate toes. The obverse of the specimen is preserved, and contains no additional toes or phalanges. Fig. 33.—Forelimb of a member of the MolgophidÆ, possibly Pleuroptyx clavatus Cope. × 0.75.
Hitherto only two portions of the dorsal series and a left limb have been assigned to this species. The present specimen (No. 4479, U. S. Nat. Mus.) thus proves of interest in determining that the creature was long-tailed, like Œstocephalus, Ptyonius, and Phlegethontia, but unlike the first two genera the neural and hÆmal spines are not elongate nor marked with radiating lines. The neural spines are indistinct and if developed at all were very low and short. The centra are short, cylindrical, and thick. They gradually decrease in size to where they are lost, since the portion preserved does not represent the entire length of the tail. There may have been 15 more vertebrÆ distally and 5 more proximally, thus making about 75 caudal vertebrÆ, as Woodward (630) has determined obtains in Ceraterpeton galvani Huxley. The ribs are continuous throughout the length of the tail preserved and have precisely the same structure as is found in the dorsal region with the possible exception that the posterior alar expansion is not so well developed in the caudal ribs. The ribs are decidedly fan-shaped and articulate by a single head with a short transverse process. They are distinctly curved like all microsaurian ribs.
The above-described specimen represents what I suppose to be the posterior part of the body of Pleuroptyx clavatus Cope. The characters of the ribs and vertebrÆ are the same. The fragment is interesting, since it gives an insight into the form of the body, which was slender, conforming thus to other long-tailed microsaurs. Length of specimen, 65 mm.; width of specimen, 30 mm. There is still a third example of this species among the collections belonging to the National Museum (No. 4484). The specimen includes a badly crushed posterior portion of a skull and a series of about 16 crushed vertebrÆ, with several pairs of ribs and ventral scutes. Very little can be said of the skull save that the maxilla of the right side was long and bore from 15 to 20 teeth, of which 9 are preserved more or less completely. The mandible is likewise crushed and one can not determine its elements. Portions of 2 or 3 teeth are preserved. The form of the mandible is long and slender. The ventral scutes are of the pectoral region. They are long, slender, and thread-like. They are not closely packed, but I count 12 in a distance of a millimeter. So far as can be determined the vertebrÆ are the same as has been described for other specimens. They are short and heavy. The ribs show, for the most part, the same characters as the type specimen.
Cope, Proc. Am. Phil. Soc., p. 177, 1871. Cope, Geol. Surv. Ohio, II, pt. II, p. 366, 1875. Type: Phlegethontia linearis Cope. This is one of the most interesting genera of the present series. It rests chiefly on a single specimen of one species, which is not perfect, but which displays the following characters: Head elongate-triangular; body and tail extremely elongate, the dorsal vertebrÆ without ribs, and the caudals without dilated spines; no ventral armature nor limbs. As a great portion of the length is presented, and no ventral rods or scales are visible, and as this character is confirmed by a second specimen, it probably belongs to the genus. The pectoral shields are also wanting in the specimen, Phlegethontia linearis Cope. Cope, Geol. Surv. Ohio, II, pt. II, p. 367, pl. xliii, fig. 2, 1875. Type: Specimen in the American Museum of Natural History. Horizon and locality: Linton, Ohio, Coal Measures. In the only specimen the dorsal vertebrÆ are much involved anteriorly, so that the length is not readily ascertained. There is an outline of a triangular object which may represent the skull of this specimen, although it is so far removed from the vertebrÆ that there is some doubt as to whether it belongs with the vertebrÆ or not. Indeed, there is even doubt whether it is a skull. The vertebrÆ have longitudinal diapophysial keels, and have a zigzag interlocking of neural arches. The latter are distinctly turned outward. The vertebrÆ are very numerous, and the tail very attenuated. The number preserved is about 60. The total length of the coils unwound is about 295 mm., or 11 coils in 8 lines; but there are interruptions not measured and confusions not unraveled. This is the most elongate and slender of all the species of the Carboniferous Amphibia. The vertebrÆ are apparently ribless and there are no evidences of limbs or pectoral plates. It may be said that the body consists entirely of skull and vertebrÆ.
No. 8370 G, American Museum of Natural History, shows a few vertebrÆ. Phlegethontia serpens Cope. Cope, Geol. Surv. Ohio, II, pt. II, p. 367, pl. 32, fig. 2, 1875. Type: Specimen No. 1102 G, American Museum of Natural History. Horizon and locality: Linton, Ohio, Coal Measures. This amphibian is much larger than the last, approaching nearly in its dimensions the Molgophis macrurus. It is represented by a series of 22 vertebrÆ, which, like those of Phlegethontia linearis, are devoid of ribs, abdominal armature, dilated neural spines, etc. The series when complete must have been very long, as there is little difference in size between the first and the last of the 22. They are marginate fore and aft, and much contracted medially, owing to the transverse expanse of the diapophyses. There may be, indeed, a diapophysial element beneath these, but, if so, the two are indistinguishable. They are connected by longitudinal impressions, indicating the existence of the tendinous bands in the longitudinal muscles seen in Amphiuma, or the osseous spicules seen in the same situation in birds. The neural spines, as indicated by their narrow bases, occupy the length of the neural arch, and remind one of Amphiuma. Width of one of the vertebrÆ, 3 lines. | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
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