.11 KAS.SK ' VERTEBRATE FOSSILS. 503 



the skull of another species, and in fig. 59 a tooth of tin- same individual is 

 also represented. < >ther allied genera of this group from the same horizon 

 are Dryosaurus and Laosaurus, the latter containing several species of very 

 small, bird-like forms. A restoration of one of these l Laos/turn* consors) is 

 shown in PL XXIV. 



The restoration given on PL XXIII is based upon the type specimen 

 of Camptosaurus dispar, one of the most characteristic forms of the great 

 group Ornithopoda, or bird-footed dinosaurs. 'The reptile is represented on 

 this plate one-thirtieth natural size. The position chosen was determined 

 after a careful study, not only of the type specimen, but of several others 

 in excellent preservation belonging to the same species or to others aearly 

 allied. It is therefore believed to be a position frequently assumed by the 

 animal during life, and thus, in some measure, characteristic of the genus 

 Camptosaurus. 'The present species, when alive, was about 20 feet in 

 length and In feet high in the position here represented. 



I I I! A l( i~AI RDS. 



The Jurassic dinosaurs above described from the Atlantosaurus beds 

 have all Keen herbivorous forms, but in the same horizon there are 

 abundant remains of carnivorous species that preyed upon them. These 

 are members of the order Theropoda, and the most important genera are 

 Allosaurus and Ceratosaurus, both large of size and ferocious in habit 

 A small, bird-like form (Coelurus) of this order lived at the same time, 

 and although of much scientific interest can not be discussed here. All 

 these carnivorous dinosaurs were bipedal in locomotion, and their general 

 form and appearance are suggested by the restoration of Ceratosaurus, 

 shown in PI. XXV. 



The genus Ceratosaurus is the best known of this group, and may he 

 taken as a typical form. The skull of the type species is shown in fig. <>0, 

 and the pelvis of Allosaurus in fig. 61. 



The skull of Ceratosaurus nasicornis is very large in proportion to the 

 rest of the skeleton. The posterior region is elevated, and moderately 

 expanded transversely. The facial portion is elongate, and tapers gradually 

 to the muzzle. Seen from above, the skull resembles in general outline 

 that of an alligator. The nasal openings are separate and lateral, and are 

 placed near the end of the snout, as shown in fig. <J<>. 



