318 



TITANOTHERES OF ANCIENT WYOMING, DAKOTA, AND NEBRASKA 



Comparative measurements of teeth of P. fontinalis, in millimeters 



placed than the hypocone; this tooth is therefore fully 

 quadrate though not precisely molariform. The well 

 preserved first superior molar (m') exhibits trenchant 

 or pointed main crescents and cones; the ectoloph 

 is divided by small, sharply ridged parastyles and 



Figure 270. — Upper molars of Palaeosyops 

 fontinalis 



Natural size. Am. Mus. 5107 (type) . Green River near mouth 

 of Big Sandy Creek, Bridger Basin, Wyo.; level Bridger A? 



mesostyles; a protoconule but no metaconule is pres- 

 ent; in size this tooth is diminutive, measuring (ap. 

 by tr.) 22 by 25 milHmeters. The a.m. /7413 i 

 anterior half of the second molar (m^) 

 is preserved; it measures 35 millimeters 

 from the outer side of the parastyle to 

 the inner side of the protocone; the 

 protocone and paracone are prominent; 

 the protoconule is reduced; the meta- 

 conule is not preserved. 



As compared with the molars of 

 P. leidyi, we note the following differ- 

 ences: (1) Ectolophs and cusps more 

 trenchant and flatter; (2) outer border 

 of the metacone ectoloph more in- 

 clined; (3) styles more sharply ridged; 

 (4) hypocone of dp* projecting more 

 internally than in corresponding tooth 

 of P. leidyi. This species is certainly 

 not a typical Palaeosyops in its denti- 

 tion, as stated above. Measurements 

 may be taken from the natural-size 

 figures of the teeth in Figure 270. 



Of the six specimens from Huerfano 

 B (see above) a finely preserved palate 

 (Am. Mus. 17411; fig. 271, A) of an 

 aged individual and the unworn upper 

 teeth (Am. Mus. 17425, fig. 271, D) 

 of a young individual afford a close 

 comparison with the two permanent teeth of the 

 type of Palaeosyops jontinalis from Bridger A 

 and are very similar both in characters and in 

 measurement. 



General specific characters of P. fontinalis. — The dis- 

 tinctive specific characters of P. fontinalis are (1) 

 parastyle very prominent; (2) protoconules reduced; 

 (3) meta- and hypocones closely compressed; (4) no 



Figure 271. — Teeth of Palaeosyops fontinalis 

 One-half natural size. Referred specimens from Huerfano B. (See p. 317.) 



trace of metaconules; (5) no hypocone on m^; (6) pre- 

 molars very simple; (7) restored palate of considerable 

 breadth; and (8) the maxillaries send back a spHnt on 

 the outer side of the malars, as in typical Palaeosyops. 



