594 



TITANOTHERES OF ANCIENT WYOMING, DAKOTA, AND NEBRASKA 

 nd lunar of type of Eotitanops borealis | Fore feet of Eotitanops princeps (type) 



The radius (Am. Mus. 4892) associated with the 

 type upper molars is incomplete; it exhibits an 

 asymmetrical proximal articular surface, and a 

 prominent internal distal projection (styloid process) 

 of the distal articular surface. 



This type (Am. Mus. 296), originally described as 

 E. iorealis and now referred to the mutation E. 

 princeps, is the only individual in which portions of 

 the fore and hind limbs, vertebrae, and jaws are 

 known, enabling us to establish the proportions. 



Figure 494. — Reconstructed skeleton and restoration of Eotitanops borealis 



Made by E. S. Christman under direction of W. K. Gregory. About one-tenth natural size. The provisionally recon- 

 structed skeleton is based on the following American Museum specimens from the Wind River Basin, Wye: No. 14887 

 (E. borealis, Dry Muddy Creek 12 miles above mouth), skull, pelvis; No. 296 (.E. princeps),, lower jaw, humerus, manus, 

 femur; No. 14888 (£. borealis, Alkali Greek, Davis ranch), part of scapula, pes. Remaining parts conjectural. 



The lunar is a very distinctive element in the lower 

 Eocene titanotheres, especially in the fact that in the 

 front view it rests mainly on the unciform and retains 

 a narrow vertical facet anteriorly for the magnum, 

 although in the back view it rests almost equally upon 

 the magnum and the unciform. This is an adapta- 

 tion to tridactylism or functional reduction of digits 

 I and V. 



The manus is numerically tetradactyl, but a strik- 

 ing feature is the slenderness of the fifth digit (Mtc V). 

 The carpus is narrow and deep — transverse measure- 

 ment 41 millimeters, vertical 34 (through cuneiform 

 and unciform). The lunar presents anteriorly a 

 superior transverse measurement of 17 millimeters as 

 compared with a total vertical measurement of 22; it 

 presents inferiorly a broad, oblique unciform facet 



