400 



TITANOTHERES OF ANCIENT WYOMING, DAKOTA, AND NEBRASKA 



are (1) the lengthening of the middle part of the skull; 



(2) the development of supraorbital horn swellings; 



(3) the character of the teeth; (4) the shape of the 



4o6 



Dolichorhinus 

 fluminalis 



Dolichorhinus 

 cornufus, type 



Sfhenodectes 

 incisivus, iype 



Dolichorhinus 

 heferodon 



Dolichorhinus 

 hyognathus 

 (cornufus) 

 Sfhenodectes 

 incisivus 



Rhadinorh/nus 

 diploconus 



Dolichorhinus 

 longiceps, type 



Dolichorfilnus 



superior, type 

 Mefarhinus 



riparius, type 



Metarhinus 



earlei 



Telmalotherium 



Dolichorhinus 

 longiceps 



Rhadinorhinus 

 abboffi 



Metarhinus 

 fluviafiiis, type 



Sphenocoelus 

 uintensis, type 



Metarhinus 

 cristatus, type 



(?Dolichorhinus 

 longiceps) 



Metarhinus 

 riparius 



-" DiplojCodoTh 

 ~f£r'~ zone 



idZA. 



ATrvynodorhskeL.Am.M:us.N9 J933 



•noo Lorv scutdstoThe^JAmynodon. irvt^rmedius 

 ' yProtelotTierium, uintense 



I EohCLSii^LLS 



< Stylinodon. 

 I ProtylopiLs 



. EohasUeus- 

 ^°J)_olic/iorkinus 

 zone 



s^tndstone^ Harpct^ol^stes 

 EobcLsileus uintensis, type 

 FieldMus. 12170 



JHobasileiis 



Triplopus 



Mesonyjc obtuside/is 



? Triplopus 



In the comparison of numerous dental series we 

 observe that the male teeth are somewhat larger, 

 including the robust, sharp-edged canines, whereas 

 the female jaws are more slender and the ca- 

 nines smaller and rounder, with shorter enamel 

 caps. Sex apparently does not affect the de- 

 velopment of the osseous horns, which are 

 practically similar in the male and female 

 skulls. 



Synopsis of species. — The following sum- 

 mary gives the principal features of the species 

 assigned to Dolichorhinus: 



UPPER LEVELS 



D. hyognathus (Osborn) = Z). cornutus Osborn. 

 Summit of Uinta B 2 and middle of Washakie B 2. 

 Cranium large, most progressive, broad and convex, 

 length 550 millimeters, breadth 240, cephalic index 46, 

 faciocephalic index 53; broad secondary palate; horns 

 well developed. 



D. fluminalis Riggs. Summit of Uinta B 2. Dis- 

 tinguished by extreme backward prolongation of 

 secondary palate. Length, type skull, 520 millime- 

 ters, breadth 233, cephalic index 45, faciocephalic 

 index 48. 



D. intermedius Osborn. Uinta B 2. A broad form 

 with elongate skull; length 485 millimeters, breadth 

 223 (estimated), cephalic index 45 (estimated), facio- 

 cephalic index 49; horns less prominent; secondary 

 palate less extended posteriori}'. 



D. heterodon Douglass. Summit of Uinta B 2. 

 Similar to D. intermedius. Length 487 millimeters; 

 cephalic index not determined; faciocephalic index 50. 



NO MAMMALS RECORDED 



Figure 338. — Geologic section of the Eohasileus-Dolichorhinus and Meta- 

 rhinus zones in the Uinta Basin 



lower jaw; (5) the broadening of the top of the skull; 

 (6) the relatively short crowns of the grinding series. 



As a whole the grinding series is short (206 mm.) 

 in proportion to the length of the skull, the molar 

 index being 38. Correlated with molar dolichocephaly 

 the inner and outer cones of the molar teeth are 

 closely approximated and the crowns are elongated 

 and narrowed. In adaptation to harder kinds of 

 food the crests and cones are elongate or subhypso- 

 dont; both the parastyles and mesostyles are very 

 sharp and prominent. 



The backward and downward prolongation of 

 the- bony palate is a very distinctive feature. In 

 early stages {D. intermedius) the secondary palate is 

 rudimentary and lies much above the plane of the 

 primary palate; in later stages it descends and lies 

 on the same plane as the primary palate, also extend- 

 ing very far backward (D . fluminalis) . 



LOWER LEVELS 



D. longiceps Douglass. Base of Uinta B 2. Very 

 abundant; more primitive; probably ancestral to D. 

 hyognathus. Horns incipient. Large size, length 545 

 millimeters, breadth 260; cephalic index of type 47; 

 faciocephalic index 48; cranial roof narrow, less arched. 



D.? vallidens (Cope). Washakie B(?). Imperfectly 

 known teeth, more primitive than those of D. hyo- 

 gnathus. 



D. (Mesatirhinus) superior (Riggs). Summit of 

 Umta B 1. Smaller and more primitive. Horns very 

 rudimentary. No secondary palate. 



Summary of cranial indices in Dolichorhinus 



The extremes of these specific indices are also 

 presented above. 



