U. S. GEOLOGICAL SURVEY 



MONOGRAPH 55 PLATE LXXXVI 



SKULL OF BRONTOPS BRACHYCEPHALUS 

 Plate prepared under the diretftion of Professor Marsh. One-fourth natural sue (See p 488, also Pis. LXXXIV and LXXXVni.) 

 Nat. Mus. 4258, skuU F, referred, Big Badlands, S. Dak., Chadron formation (Titanotherium sone), level middle B (Hatcher). 

 Al, Basal view, a partial reconftru(£lion, the adlual condition being shown in Plate LXXXVIII. The tooth rows as here repre- 

 sented are somewhat too redlilinear, and the details of the premolars are mcorrea m several points. The suture between the 

 basi-, pre-, and alisphenoids is well shown. A', Front view showing the sutural relations of the frontals, nasals, lacrimals, 

 maxillaries, malars, etc., relations which are essentially the same as in Eocene titanotheres 



