924 



EOCENE AND OLIGOCENE TITANOTHERES OF MONGOLIA 



Measurements of type, paratype, and two referred specimens of 

 Dolichorhinus kaiseni, in millimeters 



SUBFAMILY MANTEOCEEATINAE (BRONTOPINAE) 

 Protitanotherium Hatcher, 1895 



Generic characters. — The generic characters of this 

 broad-nosed titanothere as it lived in Mongolia are 

 readily inferred by comparing it with the numerous 

 skuUs and jaws of the primitive species Protitano- 

 therium grangeri, from the Irdin Manha formation, and 

 of the more progressive species Protitanotherium mon- 

 goliense and Protitanotherium andrewsi, from the over- 

 lying Shara Murun formation. The genus takes its 

 name from the resemblance of its long, broad, shallow, 

 and gently decurved nasal bones to those of Menodus 

 {= Titanotherium) and of Brontops in South Dakota. 

 The low, elongate, transversely narrow bony horns 

 resemble those of Brontops hrachycephalus. The 

 cranial proportions are correspondingly broad, de- 

 pressed; the stout, broadly expanding zygomatic 

 arches are correlated with relatively strong powers of 

 mastication; the breadth-length index of 69 (P. 

 grangeri; length 695 mm., breadth 480 mm., estimated) 

 contrasts with an index of 47 in a skull of Dolicho- 

 rhinus kaiseni of the same basilar length, 695 milli- 

 meters. The nasofrontal bony horns also are elongate 

 and are low, oblong, obtuse, but less obtusely promi- 

 nent than in Dolichorhinus. The jaws are robust and 

 have prominent coronoid processes and shallow sym- 

 physis as compared with Brontops gohiensis. The den- 

 tition harmonizes with the strong masticating power of 



Figure 780. — Jaws of Protitanotherium grangeri in place, Irdin Manha formation, upper Eocene of Mongolia 

 Messrs. Osborn, Granger, and the Chinese assistant Kan Chan Pou in the fore-ground. After Am. Mus. negative No. 251583, by B. C. Andrews. 



