ORDER VIII 



DINOSAURIA 



235 



dorsal vertebrae elongate and but slightly hollowed laterally. Sacrum com- 

 posed of four anchylosed vertebrae having slight cavities in the centra. 

 Ischia distally expanded and meeting in a ventral symphysis. Anterior 

 caudal vertebi'ae relatively small, having short, blunt transverse processes 

 and no lateral cavities. Upper Jura ; Colorado. 



Brontosaurus, Marsh (1 Amphicoeleas, Cope), (Figs. 335, 336). Total length 

 upwards of 18 m. Skull remarkably small, and brain cavity exceedingly 

 diminutive. Neck lonsi; 

 and flexible, trunk short, 

 and tail elongated. 

 About thirteen cervical 

 vertebrae, with very 

 small neural canal, and 

 no neural spines. Cer- 

 vical ribs hatchet-shaped, 

 the anterior ones fused 

 with their centra, the 

 hinder ones articulated. 

 All the centra deeply 

 hollowed, the inner 



Fig. 337. 



Morosuurus gro.ndis, Marsh. 

 Upper Jura; Wyoming. A, B, 

 Lateral and anterior aspects of 

 tooth, l/n. 



Fig. 338. 



Moroscturus grandis, Marsh. Upper Jura; Wyoming. .4, B, Lateral 

 and posterior aspects of fourth cervical vertebra, i/g. Lettering as in 

 Fig. 334. C, Pelvis viewed from in front, i/ir. a-p, The four sacral 

 vertebrae ; h, c, e, Transverse processes ; il, Ilium ; (.?, Ischium ; nc, 

 Neural eanal ; p6, Pubis (after Marsh). 



cavities of the dorsals divided by a narrow median septum. The five sacral 

 vertebrae are fused, as are also the neural spines of the three median sacrals. 

 A pair of supposed sternal bones between the perforated coracoids. Ischia 

 less robust than the pubes, somewhat expanded distally, and meeting in a 

 ventral symphysis. Upper Jura ; Wyoming and Colorado. 



Morosaurus, Marsh (Figs. 337, 338). Cervical ribs not fused with their 

 supporting processes. Neck extremely long and flexible, back short, with but 

 ten dorsal vertebrae. Chevron bones articulated by two facettes, with their 

 centra. Four sacral vertebrae. Shaft of pubes rotated distally through a 



