CHAPTER XXI. 



THE MICROSAURIAN FAMILY SAUROPLEURID/E, FROM THE COAL MEASURES 



OF OHIO. 



Family SAUROPLEURID.S Hay, 1902. 

 Hav, Bull. U. S. Geol. Surv., No. 179, p. 419, 1902. 



The present family is an association of related forms due to similar structure 

 of vertebrae, 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, Smirerpeton; limbs well developed, with well-developed digits and 

 ungual phalanges claw-like; body usually slender, broad in Saurerpeton; the ribs 

 broad and heavy; the vertebrae relatively stout; ventral armature highly developed, 

 reaching the height of specialization among the Microsauria; scutellas consisting of 

 rods, plates, or stout bristles. The family is represented by 5 genera: Sauropleura, 

 Saurerpeton, Ctenerpeton, Leptophraclus, and Eurythorax, the association of the last 

 two genera being provisional. The genera may be distinguished as follows: 



L Pectoral elements sculptured, clavicles triangular, interclavicle diamond-shaped, ventral scutellae rods, 



arranged en chevron with anterior angle Sauropleura 



IL 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 vertebrae unknown, caudal vertebrae with fan-shaped neural and haemal 



spines which may indicate relationship with Ptyonius and (Estocephalus, but in those genera the 

 ventral armature is weakly developed; ventral scutellae 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. . Leptophraclus 

 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. 



Genus SAUROPLEURA Cope, 1868. 



Newberry, Proc. Phila. Acad. Nat. Sci., viii, p. 98, 1856 {Pygoplerus scutellatus) . 

 Cope, Trans. Am. Phil. Soc., p. 22, 1869. 

 Cope, Geol. Surv. Ohio, 11, pt. 11, p. 402, 1875. 

 Hay, Bull. U. S. Geol. Surv., No. 179, p. 419, 1902. 



Type: Sauropleura scutellata Newberry. 



Vertebrae and ribs well developed; limbs 4, rather large; 5 digits in the fore- 

 foot; carpus cartilaginous. Ventral armature of closely arranged rhomboidal 

 scuta, arranged in Unes, which are closely placed in chevrons, with the angle 

 anterior. 



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