EVOLUTION OF THE SKULL AND TEETH OF EOCENE TITANOTHERES 



347 



ess, from foramen ovale to condyle 100 mm.), as 

 compared with the transverse measurements (across 

 zygomata, 300 mm., estimated; across postglenoid 

 processes, 195; across mastoid processes, 180); (2) the 

 upward slant of the basisphenoid; (3) the shortness of 

 the distance (140 mm.) between the pterygo-alisphe- 

 noid wing and the condyle; (4) the postglenoid and 

 paroccipital processes greatly flattened or extended 

 transversely with very moderate anteroposterior diam- 

 eter. 



More in detail: The posterior nares open immedi- 

 ately between m^ and m^, whereas in P. leidyi they 



as compared with 38 in D. Tiyognathus. Between the 

 foramen lacerum medium and foramen lacerum 

 posterius the basioccipital forms a prominent, later- 

 ally compressed keel. The occipital condyles are 

 comparatively slender and widely separate below the 

 foramen magnum. This aspect of the skull illus- 

 trates admirably (1) the broadly transverse extension 

 of the articular facets for the condyle of the jaw, (2) 

 the broadening of the postglenoid processes, (3) the 

 separation of the postglenoid and post-tympanic, 

 which is much wider than in the brachycephalic P. 

 major but very much narrower than in the dolichoct - 



•p.ty.sq. 

 ^'pgl.sj. 



Figure 295. — Type skull of Telamatherium uliimum 



One-fourth natural size. Am. Mus. 2060. White River, Uinta Basin, Utah; base of Uinta C, true Uinta formation. Ai, Side view. The depth of 

 the sltull in the middle region and immediately in front of the orbit has been increased by lateral crushing. The double lines mark the plane of 

 the sections in Figiu-e 255, Bi, Bj. Aj, Front view. As, Occipital view. 



open opposite the posterior half of m^, and in Oligocene 

 titanotheres they often open opposite the posterior half 

 of m'. The postnarial space is relatively deep, or ver- 

 tically extended, and short anteroposteriorly ; the 

 line of junction between the pterygoid wings of the 

 alisphenoids and the palatines can not be clearly made 

 out. Unlike those of M. megarJiinus or P. major the 

 pterygoids and lateral wings of the alisphenoids descend 

 abruptly. The foramen ovale is separated from the 

 foramen lacerum medium by a bridge, 24 millimeters 



phalic D. hyognathus; (4) also the sharply produced 

 downward flange of the posterior portion of the malar. 



The superior aspect of the skull (fig. 296) fails to 

 give the actual shape of the nasals owing to the 

 marked crushing at this point. The entire length of 

 the nasals is 219 millimeters, as compared with 520, 

 the entire length of the vertex. 



Horn rudiments. — In the type female skull there is 

 no evidence of the existence of a horn swelling at the 

 junction of the frontals and nasals. In the paratype 



