406 



TITANOTHERES OP ANCIENT WYOMING, DAKOTA, AND NEBRASKA 



The more exact level, however, is not stated. Only 

 from thehr less progressive condition does it appear 

 probable that they belong to a somewhat lower 

 geologic stage than the typical D. Jiyognathus. 



Proportions. — These animals are smaller than those 

 referred to D. Jiyognathus. The type skull belongs to 

 a young adult female with canines proportioned as in 

 the females of the type species. The total length 

 (462 mm.) is somewhat inferior to that of the older 

 animal (Am. Mus. 2001), in which the length is 

 485 millimeters, as compared with an average of 550 

 in D. Jiyognathus. Similarly the superior grinding 



series measures 179 

 millimeters, as com- 

 pared with 156 in 

 Mesatirhinus peter- 

 soni and 206 in D. 

 hyognathus. 



Comparison with 

 D. (cornutus) hyo- 

 gnathus. — The crania 

 are of inferior di- 

 mensions throughout. 

 The nasals are nar- 

 rower anteriorly; the 

 horns are less prom- 

 inent and are borne 

 entirely on the nasal 

 bones; the flattened 

 vertex of the skull in 

 the parieto-occipital 

 region is relatively 

 narrow. 



The incisors, as 

 shown by i', pre- 

 served in Am. Mus. 

 2001,are deeply pitted 

 or pocketed, posteri- 

 orly. P' is a small, 

 simple tooth, less 

 broadened anteriorly 

 than in any speci- 

 mens of D. hyogna- 

 thus. The common 

 characters as com- 

 pared with B. hyo- 



1837 (type), White River, Uinta Basin, Utati, gnathuS in P^-p'' are : 



(1) The crowns are 

 less hypsodont throughout; (2) the protocone con- 

 vexities on the ectolophs are more convex or less 

 sharply constricted; (3) the tritocone convexities, on 

 the other hand, are somewhat more prominent; (4) 

 the deuterocones are more rounded or conic, and there 

 is less prominence of the internal cingula and of the 

 protoconules. All these characters indicate a lesser 

 degree of progression. 



Additional note on Doliehorhinus intermedius. — Three 

 skulls in the Carnegie Museum from Uinta B 2 

 (middle levels), Nos. 3094, 3095, 3096, collected by 



Doctor Douglass, are referred to this species. The 

 principal dimensions of two of these are given below: 



Measurements of skulls of Doliehorhinus intermedius, in milli- 

 meters 



Figure 342. — Skull of Doliehorhinus 



intermedius 

 Top view. One-tourth natural size. Am. Mus. 



1837 (ty: 



Uinta B 2. 



Pmx-condyles 



Transverse zygomata (estimated) 



Pi-m3 



Pi-p* 



M"-m3 



472 

 170 

 176 

 70 

 103 



462 



Doliehorhinus longiceps Douglass 



Plates XXX-XXXII, LXXIII, LXXV-LXXVII; te.xt figures 

 135, 136, 254, 335, 339, 340, 343-346, 353, 589-591, 724 



[For original description and type references see p. 188. For sjceletal characters see 

 p. 651] 



Type locality and geologic horizon. — Uinta Basin, 

 Utah; Eobasileus-Dolichorhinus zone (Uinta B 2). 

 Geologic range 300 to 400 feet. 



Specific characters. — Horn bases small; cranium 

 large, 530-550 millimeters; breadth, 264-240; cephalic 

 index 44-47; secondary palate in early stage of 

 development, lying above level of primary palate; 

 cranial vertex narrow posteriorly; premolars with 

 relatively feeble internal cingula. 



Geologic distribution. — The type skull of this prim- 

 itive and clearly defined species, recorded by 

 Douglass as "700 feet below Uinta red beds," would 

 place the type well down in Uinta B 2. The four 

 skuUs (Field Mus. 12175, 12176, 12193, 12200) 

 collected by Riggs extend from the lower to the upper 

 portion of Uinta B 2 or the "upper Metarhinus beds" 

 of Riggs. These specimens are somewhat smaller 

 and less specialized than the type; they vary in length 

 from 525 to 560 miUimeters. 



Type.-^^he. type skuU of Douglass has been dis- 

 torted from right to left and from above downward, 

 so that the left upper part is tilted and overhangs 

 the left temporal fossa and orbits. The right pre- 

 maxillo-maxillary rostrum is flat, and the general 

 wearing plane of the left tooth row is tUted toward 

 the right, while the parietofrontal vertex above the 

 squamosal region is squeezed up into a long antero- 

 posterior convexity. 



This distortion makes it difficult to determine what 

 are the real structural differences from D. hyognathus, 

 but the judgment of Douglass in separating this species 

 is fully confirmed by the skuUs discovered by Riggs 

 in Uinta B 1 and B 2. One skuU (Am. Mus. 1852), 

 presumably that of a female in regard both to measure- 

 ments and to characters, appears to bridge over the 

 differences between this species and the type of 

 D. cornutus { = JiyognatJius), as shown in the following 

 measurements : 



