630 DR. R. BROOM ON 



group which agrees quite as much with the Rhynchocephalia and 

 the Carnivorous Dinosaurs as with the Crococlilians. 



Though tliese two opinions seem at fii-st sight to be at variance 

 they are I'eally pretty similar. Practically, it amounts to this, 

 that in the Pseuclosuchia we have a group of primitive reptiles 

 which, while they do not fit into any of the later specialised 

 orders, have affinities with quite a number of other groups. 



There cannot, I think, be the slightest doubt that tlie Pseudo- 

 suchia have close affinities with the Dinosaurs, or at least with 

 the Theropoda. This has been recognised by Marsh, v. Huene, 

 and others. In fact there seems to me little doubt that the 

 ancestral Dinosaur was a Pseudosuchian. The skulls of such types 

 as Eiqyarkeria or Ornithosuchus are practically Dinosaurian even 

 in detail, and the skulls of the early Dinosaurs, ^ch as Anchi- 

 saurus, differ less from the skulls of Pseudosuchians than those 

 of the early Dinosaur^i do from many of the later types. And 

 there is nothing in the post-ci'anial skeleton that is not just what 

 we should expect to find in the Dinosaur ancestor. The shoulder- 

 girdle is more primitive in retaining clavicles and interclavicle, 

 but these are elements which we know from the history of other 

 groups are ver}^ variable and readily lost. The pelvis is almost 

 Dinosaurian, and differs only in having the acetabulima closed. 

 This is an important character ; but when we consider the con- 

 dition in the two nearly allied Monotremes — the one with the 

 acetabulum closed, the othei' with it open — we see how easily even 

 this character may change. The hind limb is almost Dinosaurian 

 in Eaparkeria. The ankle is less specialised and the fifth toe is 

 sbill well developed and retains the Rhynchocephalian characters. 

 Ktijparkeria is in my opinion potentially bipedal, and was probably 

 partly bipedal in its habits. The fourth toe of the hind foot is 

 more feebly developed than the third and the axis of the foot is 

 down the third toe, which would seem to indicate that the feet 

 were at least not so laterally placed as in lizards, and that the 

 animal possibly ran on its hind feet. The relative shortness of the 

 toes also seems to confirm this view, as well as the feebleness of 

 the fore limbs. I believe Kvpavke.ria fed on some large forms of 

 insects like locusts, and captured them with its front feet. 



Ornithosuchus was probably very similai' in habit to Euparlieria 

 a,iul was even a little better adapted for running on its hind feet ; 

 the large species 0. taylori coulcl hardly have had the same habits 

 as tlie small 0. looodioardi. It is too massively built, and probably 

 had become largely carnivoious, adding to the larger insects various 

 small vertebrates, and perhaps, like the vulture, the flesh of 

 animals too large for it to kill. 



The affinities of such small Pseudosuchians as Euparkeria, 

 Ornithosuchus, and Aetosaurus with the Belodonts through such 

 an intermediate form as Erythrosuchus is very manifest. And as 

 Boulenger stated, the Pseudosuchians are about as near to the 

 Parasuchians as to the Dinosaurs. The series of dermal plates 

 down the back, though suggesting affinity is, however, not a 



