FOSSIL VERTEBRA TES— REPTILIA 633 
The skull was very birdlike in general outline; both the 
upper and Jower jaws were full of small, sharp teeth that inclined 
toward the anterior ends of the jaws, and were not differentiated 
into molar and incisor regions (this feature oécurs only in the 
most specialized of the reptilia) ; the fore limbs were much 
smaller than the hind limbs, but were quite large in comparison 
with those of the more specialized forms of later time, and 
perhaps took a large part in walking, although the hind limbs 
undoubtedly were the most largely used; all the bones of the 
limbs were hollow, and had very thin and solid walls, as in the 
birds; the fore foot had five digits, only four of which were 
functional; the hind limb had four toes on the foot, the fifth 
being a mere rudiment and the first much smaller than the 
others, so that the track would have been that of a three-toed 
animal. It is altogether probable that many, if not all, of the 
so-called bird tracks of the Connecticut Valley sandstone were 
made by these animals. One species had a length of nearly six 
feet, while another was much smaller, no larger than a ‘small 
TO 
Thecodontosaurus is one of the few European Triassic Dino- 
saurs that are known. It is from the Rhaetic of Bristol in Eng- 
land. The form is known from teeth and from portions of the 
skeleton; the teeth are of the typical carnivorous type, and are 
serrated on the anterior and the posterior borders. 
Zanclodon (Plateosaurus) is from the Trias of many parts of 
Germany. The teeth are curved backward as in the preceding 
genus, and are serrated on the anterior and the posterior edges ; 
the vertebre are deeply bi-concave, and are very much longer 
and smaller in the cervical than the dorsal region; the limbs 
were short and strong and the jaws were long and curved. Only 
a part of the skeleton is known, although several specimens have 
been discovered; altogether there are about sixty vertebre pre- 
served in series, and these have a length of nine feet; the form 
is remarkable in being one of the few Dinosaurs that have bi-con- 
cave vertebre. 
Epicampodon isa form from the Trias of the East Indies, 
