[CHAPTER XXI.]
THE MICROSAURIAN FAMILY SAUROPLEURIDÆ, FROM THE COAL MEASURES OF OHIO.
Family SAUROPLEURIDÆ Hay, 1902.
Hay, Bull. U. S. Geol. Surv., No. 179, p. 419, 1902.
The present family is an association of related forms due to similar structure of vertebræ, ribs, ventral scutellation, and limbs. There is no character in the skull which would indicate a separation of the genera here included, at least in the light of present knowledge.
The family may be characterized as: Subaquatic or terrestrial vertebrates with a typically amphibian development of the ventral armature; ribs intercentral, as in all members of the order; skull elongate and slender or broad and obtuse; cranial and dermal elements of the pectoral girdle sculptured; lateral-line canals indicated in one genus, Saurerpeton; limbs well developed, with well-developed digits and ungual phalanges claw-like; body usually slender, broad in Saurerpeton; the ribs broad and heavy; the vertebræ relatively stout; ventral armature highly developed, reaching the height of specialization among the Microsauria; scutellæ consisting of rods, plates, or stout bristles. The family is represented by 5 genera: Sauropleura, Saurerpeton, Ctenerpeton, Leptophractus, and Eurythorax, the association of the last two genera being provisional. The genera may be distinguished as follows:
| I. | Pectoral elements sculptured, clavicles triangular, interclavicle diamond-shaped, ventral scutellæ rods, arranged en chevron with anterior angle | [Sauropleura] |
| II. | Pectoral elements slightly sculptured, cranium broad, obtuse and sculptured, ventral armature broad imbricated plates extending on to the throat | [Saurerpeton] |
| III. | Limbs, skull, arches and dorsal vertebræ unknown, caudal vertebræ with fan-shaped neural and hæmal spines which may indicate relationship with Ptyonius and Œstocephalus, but in those genera the ventral armature is weakly developed; ventral scutellæ curved rod-like plates arranged en chevron with anterior angle, marked in abdominal region by distinct rounded pits | [Ctenerpeton] |
| IV. | Known only from fragments of the skull, teeth large and fluted; association in family provisional | [Leptophractus] |
| V. | Known only from a single interclavicle of peculiar form which resembles that of Saurerpeton; association in the family provisional | [Eurythorax] |
The members of this family are confined to the deposits of the Coal Measures at Linton, Ohio. Ctenerpeton, and possibly Sauropleura, were highly developed swimmers, but the strength of the limbs as exhibited, especially by Sauropleura and Saurerpeton, indicates that they had not entirely forsaken the land.