650 



TITANOTHERES OF ANCIENT WYOMING, DAKOTA, AND NEBRASKA 



The other cervical vertebrae present no characters of sufficient 

 importance to mention in this connection. 



The dorsal vertebrae. — The first dorsal has a short depressed 

 centrum and a prominent keel. The spine and transverse 

 processes are broken off. The other dorsal vertebra belongs 



therium. The coracoid border above the notch is more curved 

 forward, as is also the glenoid border. The general outlines 

 of the scapula are on the whole more suggestive of the Rhino- 

 cerotidae than the titanotheres. 



The humerus. — The humerus is short and heavy. The bone is 

 comparatively shorter than in Eotitanotherium. Unfortunately, 

 the greater tuberosity is broken on the posterolateral face, but 

 near the deltoid groove the superior face is complete and indi- 

 cates very plainly that the tuberosity is not as high as in 

 Eotitanotherium. The lesser tuberosity accords more nearly 

 with that shown in the latter genus. The deltoid groove is also 

 of about the same size in the two genera here compared. The 

 deltoid ridge is less prominent in Dolichorhinus, while the distal 

 end of the bone is quite nearly alike in the two genera. 



A 



Figure 586. — Manus of Amynodon and Mesatirhinus compared 



A, The amphibious rhinoceros A. intermedius?, Am. Mu-s. 1961; B, the terrestrial 

 mediportal titanothere M. ■petersoni?, Princeton Mus. 10013. One-third natural 

 size. 



well back in the series and has a higher and more evenly rounded 

 centrum, without ventral keel, but with the indication of a 

 heavy neural spine. 



The lumbar vertebrae. — The two last lumbar vertebrae are 

 present; the body of the last being depressed, as is usual in the 

 case of the last lumbar, and has also the neural spine suddenly 

 reduced in the fore-and-aft direction. The transverse process 

 of the same vertebra is quite heavy and projects outward and 

 forward. Near the base of the process on the posterior face 

 there is a heavy and rounded process, which possibly came in 

 close contact with a similar process on the anterior face of the 

 pleurapophysis of the first sacral vertebra. 



When the vertebrae described above are compared with the 

 vertebral column of Dolichorhinus hyognathus it appears that 

 the neural spine of the atlas of the specimen in New York is 

 more prominent, while the position of the transverse process 

 and the anterior exit of the vertebrarterial canal of the a.xis 

 appear to be the same in the two specimens. The cervical 

 series as a whole appear to be slightly shorter in the specimen 

 preserved in New York (D. hyognathus). 



Measurements of Dolichorhinus longiceps 



Millimeters 



Atlas, greatest anteroposterior diameter 105 



Atlas, greatest transverse diameter, approximately 180 



Atlas, greatest vertical diameter 88 



Axis, anteroposterior diameter of centrum, odontoid process 



included 95 



Axis, height, including neural spine 125 



Cervical region, total length, approximately 395 



The scapula. — The scapula is little if any shorter than in 

 Eotitanotherium, as figured by Peterson, but its general out- 

 lines differ from those shown in that genus. The lower portion 

 of the coracoid border is more deeply notched than in Eotitano- 



FiGURE 587. — Left fore limb of the amphibious rliinoceros 



Amynodon intermedius? 

 Am. Mus. 1961, Uinta B 2. Formerly referred to Dolichorhinus. Ai, Outer 



side view; A2, front view of forearm and manus; B, front view of humerus. 



One-sixth natural size. 



The radius and ulna. — The radius and ulna are much shorter 

 than in Eotitanotherium and proportionally also much heavier. 

 There is a tendency to coossification of the two bones in the 

 present specimen, the shaft is rounder, and the articulation for 

 the humerus is less deeply excavated than in Eoliianotherium. 

 In comparing the ulnae of the two genera in more detail, it is seen 

 that there is a less developed tubercle on the outer margin of the 

 tendinal groove of the olecranon process in Dolichorhinus than 

 in Eotitanotherium. In consequence the groove is not as well 

 defined in the genus under description, though the termination 

 of the olecranon process is fully as well developed. In Dolichc- 

 rhinus there is a greater constriction of the olecranon between 

 the upper border of the great sigmoid notch and the termina- 

 tion of the process than is seen in Eotitanotherium. Otherwise 

 the ulna is cjuite similar in the two genera. 



