174 



TITANOTHERES OF ANCIENT WYOMING, DAKOTA, AND NEBRASKA 



seen in the anterior view, Figure 110. Ttiese characters and 

 the absence of the frontoparietal and interparietal sutures all 

 point well toward Titanotherium, but the premolars are still 

 absolutely simple, showing no trace of the postero-internal cusps 

 which characterize Diplacodon elatus. 



Other striking peculiarities are the upward-arching mid- 

 cranial region, the extremely long, narrow, and laterally de- 

 curved nasals; the strong infraorbital shelf upon the molars 

 [malars] (seen also in T. megarhinum) , the slender zygomatic 

 arch, the low occiput, the backward extension of the posterior 

 nares by the palatines, and the partial inclosing of the roof of 

 the pharynx by the pterygoids. 



Sphenocoelus Osborn, 1895 



Cf. Sphenocoelus Osborn, this monograph, page 417 



Original reference. — Am. Mus. Nat. Hist. Bull., vol. 

 7, pp. 98-102, 1895 (Osborn, 1895.98). 

 Generic characters. — Osborn writes: 



The distinctive features of the skull may therefore be summed 

 up as follows: Deep paired pits in the aUsphenoids, and orbito- 

 sphenoids upon either side of the thin presphenoid [basisphenoid] ; 

 a long alisphenoid canal; foramen ovale widely separated from 



Figure 110. — Type (holoty 

 Side, front, and top views of skull. Am. Mus. 



This general description of character was followed 

 by a more detailed description. 



Etymology. — cornutus, horned; in allusion to the 

 osseous "horns." 



Present determination. — Comparison of the lower 

 jaw with the type of Palaeosyops hyognathus Osborn 

 indicates that the species T. cornutum is a synonym of 

 P. hyognathus, a species which is now referred to the 

 genus Dolichorhinus. 



pe) of Tebnatotherium cornutum 



1851. After Osborn, 1S95. One-fourth natural size. 



1 for. lac. medium; condjdes very broad; foramen magnum 

 large; occipital crest extending anteriorlj' into a short sagittal 

 crest with convex sagittal ridges; skull apparently long and 

 narrow. 



Etymology. — <T4>riv, a wedge; koIXos, hollow; in allusion 

 to the paired cavities in the basisphenoid bone. 



Present determination. — This is a valid genus of 

 Eocene titanotheres related to the long-skulled 

 Dolichorhinus. (See p. 417.) 



