150 DINOSAURS OP NORTH AMERICA. 



is very large. The quadrate is inclined forward, and the lower jaw is 

 robust. The entire skull is about 65 mm long, and the lower jaws are 

 of the same length. 



The neck was very long and slender, the first five cervicals measur- 

 ing 80 ,um in extent. The dorsals are also elongated, the last six cover- 

 ing a space of 135 m,n . The number of vertebrse in the sacrum can not 

 yet be determined. The caudal vertebras are short, the first ten occu- 

 pying a space of 110 ,um . 



The humerus has a very large radial crest, and is 66 mm in length. 

 The rest of the fore limb, so far as made out, is similar to that in the 

 species described. The tibia is about 88 ,um in length. There were five 

 digits in the hind foot, but the fifth is represented only by the rudi- 

 mentary metatarsal. The animal was about as large as a small fox. 



AMMOSAURUS. 



The genus Ammosaurus, represented by remains of larger size from 

 the same strata, was also a typical carnivorous dinosaur, and appar- 

 ently a near ally of Anchisaurus. So far as at present known, the 

 footprints of the two reptiles would be very similar, differing mainly 

 in size. 



On PI. Ill, fig. 6, is shown an entire hind foot of Ammosaurus, oue- 

 fonrth natural size. In this foot the tarsus is more complete than in 

 Anchisaurus. The astragalus has no true ascending process, the cal- 

 caneum is closely applied to the end of the fibula, and there are three 

 well-developed bones in the second row. The fifth digit had only a 

 single phalanx. The sacrum and ilia of the type species of Ammo- 

 saurus are shown in fig. 3, and the ischia of Anchisaurus in fig. 4. 



RESTORATION OF ANCHISAURUS. 

 Plate IV. 



The Triassic dinosaurs known from eastern North America have now 

 been briefly reviewed. Remains of seven individuals are sufficiently 

 well preserved to indicate the main characters of the animals to which, 

 they pertained. These were all carnivorous forms of moderate size, 

 and the known remains are from essentially the same geological horizon. 



The genus Anchisaurus, one of the oldest known members of the 

 Theropoda, is so well represented by parts of four skeletons from these 

 deposits that a restoration of one species can now be made with con- 

 siderable certainty. This has been attempted, and the result is given, 

 one-twelfth natural size, in the accompanying PL IV. The animal was 

 about 6 feet in length. 



The skeleton chosen for this restoration is the type specimen of 

 Anchisaurus colurus, described by the writer in the American Journal 

 of Science in 1891 and 1893. This skeleton when discovered was entire, 

 and apparently in the position in which the animal died. Portions of 



