112 Williston — Dinosaurian Genus Creosaurus^ Marsh. 



this same vertebra, used to typify Allosaurus, is figured as 

 Creosaurus. 



The interesting fact remains that the author of Creosaurus 

 did not and apparently could not satisfactorily distinguish it 

 from Allosaurus, and the name has remained in catalogues 

 and text-books as a sort of floating wreckage, that will neither 

 sink nor be cast np. The few characters Marsh gave for 

 Creosaurus, it is readily seen are of very slight value. The 

 ilium, it is true, is of somewhat different shape, as figured, but 

 even this difference may be due to imperfect preservation, as 

 Marsh himself suspected. The only other things mentioned 

 by Marsh is the number of vertebrae in the sacrum, of very 

 little value as already demonstrated in other genera of the 

 Wealden dinosaurs ; the position of the transverse processes, 

 which 1 am confident will not prove distinctive ; and the num- 

 ber of teeth in the premaxilla. In fact, then, nothing seems 

 to be known as certainly belonging to Creosaurus, except the 

 imperfectly preserved ilium first described. 



In the Kansas University expedition to Wyoming in the 

 summer of 1899, a number of bones of a carnivorous dinosaur 

 were obtained from a deposit in the Freeze Out Mts., asso- 

 ciated with remains of Morosaurus, Diplodocus, Stegosaurus 

 and Antrodemus. These remains were at first unhesitatingly 

 referred to Allosaurus, and it is possible that some of them 

 may really belong with that genus. The numerous centra pre- 

 served certainly agree very closely with the description given 

 of the Allosaurus vertebrae— but they also agree equally well 

 with the vertebra referred to Creosaurus. Aside from the 

 vertebrae, however, there were two scapulae obtained that 

 certainly show a generic distinction from Allosaurus, as I have 

 convinced myself from inspection of the scapula referred by 

 Marsh to that genus, and figured by him in various places. It 

 remains to be seen, however, whether this scapula of Marsh 

 indubitably belongs with the bones first referred by him to 

 Allosaurus. I do not think that there is conclusive evidence 

 of this. Associated with these scapulae in our quarry, though 

 not in immediate juxtaposition, were two coracoids, a humerus, 

 radius, claw bones, etc., all of which belong I think with the 

 same species, though from two animals. An ilium and femur, 

 obtained .later from the same deposit by the Field Columbian 

 expedition, in all probability belong with one or the other of 

 the two animals. 



I give herewith a restoration of the shoulder girdle and arm, 

 so far as the bones preserved permit. The portions outlined 

 are reproduced from Marsh's restoration of the corresponding 

 parts of Allosaurus. 



