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VII. — Report on the Reptilian Fossils of South Africa. 



Part II. — Description of the Skull of a large species of Dicynodon (D. tigriceps, 

 Ow.), transmitted from South Africa hy A. G. Bain, Esq. 



By Professor OWEN, F.R.S., F.G.S. 



[Read May 16th, 1855.] 



Plates XXIX. to XXXII. 



Of the extinct Reptilia hitherto discovered in different regions of the globe, the 

 fossil skulls of some species have exhibited combinations of characters now pecu- 

 liar to distinct orders of the class, or even to distinct classes of Vertebrate animals. 

 The Ichthyosaurus, for example, shows the piscine proportions of the premaxillaries 

 in the upper jaw : the Rynchosaurus shows the chelonian absence of teeth in both 

 jaws : but the Dicynodon seems to have borrowed its peculiarities from a higher 

 class, and to have engrafted some mammalian characteristics upon the upper jaw, 

 whilst it combined a chelonian edentulous under jaw, and a crocodihan occiput, 

 with a cranium essentially constructed after the lacertian type. 



These and most of the minor peculiarities of the cranial organization of the 

 Dicynodont reptiles have been pointed out in my former account of some of the 

 smaller species of the genus*. There were, however, in Mr. Bain's first collection 

 some fragments indicative of a Dicynodon, with subcompressed tusks (D. Bainii), as 

 large as a Walrus, but these were too scanty to deserve more than a reference to 

 their indication of the size to which some species of that peculiar genus of reptile 

 had attained during the mesozoic period in South Africa. 



In a subsequent transmission of fossils from the Graaf Reinet district and 

 Kafraria by Mr. Bain, two almost entire skulls of a still larger species of Dicynodon 

 with circular tusks were included. They have been ably relieved from their 

 extremely hard matrix by Mr. Dew at the British Museum, and they exhibit, with 

 the long descending upper canines of the genus, a proportion and shape of the 

 temporal fossse more like those in the larger mammalian Carnivora, than in any 

 known reptile, or than was indicated in any of the previously described smaller 

 species of Dicynodon. Thus, of all the modifications of cranial structure which the 

 fossil remains of extinct reptiles have offered to the contemplation of the naturalist, 

 none have exhibited combinations of characters more extraordinary and suggestive 

 than those presented by the old extinct Bidental Lizards of South Africa. 



* Vide supra, p. 59. 



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