150 PROCEEDINGS OP THE PALEONTOLOGICAL SOCIETY 



some characters it recalls the Eocene Anaptomorphida?, but the pattern of the 

 premolars and molars is fundamentally similar to that of its contemporary. 

 Proplio pith ecus Schlosser, which is a true anthropoid, much smaller than the 

 gibbon and foreshadowing the Pliopit It ecus-gibbon line as well as Dryopitliccus, 

 the Chimpanzee, and the Gorilla-man group, as held by Schlosser. Dryo- 

 pithecus of the Upper Miocene includes six species — three from India, recently 

 described by Pilgrim, and three from Europe, known chiefly from molar teeth 

 and lower jaws. To the writer D. punjaMcus and the later D. rhenanus appear 

 to be ancestral to the Chimpanzee, while D. chin jicn sis and perhaps /). fontani 

 appear to lead to the Gorilla. 



Pakrosiiiiia Pilgrim, from India, is known from a third upper molar which 

 foreshadows that of the Orang. Sivapithecus Pilgrim, from the Chinji zone 

 of the Lower Si walks (Upper Miocene) strongly suggests the Horn laicise in its 

 wide molars and bicuspids, but retains the primitive apelike canines. In the 

 Dryopithecits group (including Firapitliccus) there is a very special resem- 

 blance and affinity in the patterns of all the upper and lower premolars and 

 molars to those of the HoininicUe, which family may well have been derived 

 from some Upper Miocene member of that group. The retraction of the jaws 

 and the reduction in size of the canines and front lower premolars in the 

 Hominida? are retrogressive characters, as is also the reduction in the pattern 

 of the second and third upper molars from a more quadritubercular to a 

 tritubercular condition. 



Paper discussed by Professor Osbom, Doctor Miller, and Doctor Case. 

 Remarks by Professor Osborn on Pan veins from Third Interglacial of 

 Tailback (a Chimpanzee of Pleistocene age). 



ADDITIONAL CHARACTERS OF TYRANNOSAURUS AND ORNITHOMIMVS 

 BY HENRY FAIRFIELD OSBOEN 



{Abstract) 



The complete skeletons of Tyrannosaurus and Omithomimits recently secured 

 and mounted in the American Museum of Natural History render possible a 

 thorough comparison of these two extreme types of adaptation. Tyramiosaurus 

 is highly specialized, both in the skull, fore limb, and the hind limb, as a flesh- 

 eating type, capable of overcoming and devouring the most formidably defended 

 prey ; in other words, it is an example of harmonious adaptation throughout. 



The discovery of the skull and fore-limb structure of OrnitliODiimit* has 

 afforded one of the greatest surprises in the whole history of vertebrate 

 paleontology. Although descended from the same stock as Tyrannosaurus, as 

 indicated by many common points of structure, as well as by its relationship 

 to Ornitholestes of the Lower Cretaceous, this animal has diverged as widely 

 as possible from the raptorial type. The chief feature is the entire absence 

 of teeth and the modification of the skull and jaws into a beak closely 

 analogous to that of the struthious birds. The feet have entirely lost their 

 prehensile or raptorial powers and developed cursorial adaptations very sim- 

 ilar to those of the rhea and the cassowary. 



Regarding the skull and the feet alone, it might be possible to regard this 

 as an ostrich-like or struthioid dinosaur and browser, adapted to subsisting on 



