NORTH AMERICA AND THEIR VERTEBRATE FAUNA. 



143 



etc., appropriate to that genus. The skull, long considered as belonging to a 

 totally different type of animal, the scapula, pelvis, and the proportions of 

 the limb bones have all been shown to be radically different from those of 

 the Dimetrodon. The skull was rather short and high, with large orbits near 

 the middle. The teeth upon the edges of the jaws are conical, with accessory 

 crushing-teeth upon the palate and dentary. The scapula was very broad 

 and heavy. An isolated scapula of this form was found many years ago by 

 the author and supposed to belong to a diadectid, but, as has recently been 

 shown by Case and Williston,'' probably belongs to Edaphosaurus. 



The limbs were shorter than in Dimetrodon, owing largely to the short 

 fore limb, indicating a creeping habit and much slower motion. No foot 

 bones have been certainly associated with this genus. A very large, claw-like 



-'\t«U' 



Fig. 29. — ^Restoration of Edaphosaurus cruciger Cope. About one-tenth natural size. 



ungual phalanx is associated with a specimen in the American Museum, and 

 well-modeled tarsal and carpal bones, not assignable to Dimetrodon or Dia- 

 dectes, have been found in the Brier Creek bone-bed, associated with bones of 

 Edaphosaurus, but the evidence is too unsatisfactory to be accepted without 

 question. It is not improbable that the feet were strong, and provided with 

 powerful scratching or digging claws. 



The dorsal spines differed somewhat in the different species. In Edapho- 

 saurus claviger the spines of the cervical vertebrae were expanded and clavate 

 at the top; in Edaphosaurus cruciger they were very little or not at all ex- 

 panded. The dorsal spines began immediately behind the skull, rose rapidly 

 to their full height, and continued to the pelvic region, where they terminated 

 abruptly. The spines of the first caudal vertebrae are abruptly reduced in 



" Carnegie Inst. Wash. Pub. 181, p. 78, 1913. 



