MARSH.] 



PLATE0SACRID.3E. 



235 



during the life of the animal, an essential part of the remarkable leap- 

 ing foot to which it belonged, and in which it has since kept its posi- 

 tion undisturbed. The presence of such an element in the foot of this 

 diminutive dinosaur certainly suggests that the group Hallopoda, 

 which the writer has here considered a suborder, stands somewhat apart 

 from the typical Theropoda, but not far enough away to be excluded 

 from the subclass Dinosauria, as defined in the present paper. 



The genus Plateosaurus (Zanclodon), which is from essentially the 



Fig. 63. — Pelvis of Morosaunts lentus Marsh; seen from the left. 

 a, acetabular opening; other letters as in fig. G2. 



One-eighth natural size. 



same geological horizon in Germany as Aetosaurus and Belodon, is one 

 of the oldest true dinosaurs known, and a typical member of the order 

 Theropoda. In the pelvic arch of this reptile the ilium and ischium are 

 in type quite characteristic of the group to which it belongs, but the 

 pubic elements are unique. They consist of a pair of broad, thin 

 plates united together so as to form an apron-like shield in front, quite 

 unlike anything known in other dinosaurs. The wide pubic bones of 

 Belodon, and the corresponding plates in some of the Sauropoda (Moro- 

 saurus, fig. 63). indicate that this feature of the reptilian pelvis may 



