230 



THE OSTEOLOGY OF THE REPTILES 



well, and is still used often in that original sense or with the exclusion 

 of the Cotylosauria. 



There is greater diversity among the Theromorpha as thus dis- 

 tinguished than among the Cotylosauria, the only constant differ- 

 ences from which are the perforated temporal roof, the longer neck, 

 and usually longer legs. Doubtless they were more active and agile 

 animals, and their adaptive radiation was greater. But the primitive 

 characters were less constant. The intertemporal bone is never 



Fig. i66. Skeleton oi Edaphosaurus (Theromorpha). 



present; the interparietals, tabulars, and supratemporals are always 

 smaller; some may be wanting, and the two former are always con- 

 fined to the occipital surface when present. The quadratojugal is 

 smaller; the lacrimal seldom extends to the nares. The teeth are 

 often wanting on the prevomers ; the postsplenial is never present in 

 the mandible though there is a possibility of an additional coronoid, 

 the posterior one of which is always present. The humerus has an 

 ectepicondylar foramen only in the Edaphosauridae; the entepicon- 

 dylar foramen is always present. The plate-like pelvis never has a 

 large pubo-ischiatic or a true thyroid foramen. There are two or three 

 sacral vertebrae. The fifth tarsale is rarely unossified. No dermal 

 bones have been discovered in any member of the order, and para- 

 sternal ribs are known only in the PoKosauridae and Ophiacodon- 



