292 



TITANOTHERES OF ANCIENT WYOMING, DAKOTA, AND NEBRASKA 



conid, Pa laterally compressed, hypoconid distinct, 

 paraconid, metaconid, and entoconid extremely rudi- 

 mentary rectigradations. In the molar teeth, mi_3, 

 the metastylid and entostylid are also in an extremely 

 rudimentary or rectigradational stage. In ma the 

 hypoconulid is small, subconic, external in position. 

 (See fig. 235.) 



Eotitanops brownianus (Cope) 



Text figures 104, 143, 231, 246, 247, 253 

 [For original description and type references see p. 169] 



Type locality and geologic horizon. — Wind River 

 Basin, Wyo.; Wind Eiver formation, Lambdotherium- 



c-fSS^' 



Figure 247. — Lower jaws of Eotitanops gregoryi and E. brownianus 



One-half natural size. A, E. gregoryi, Am. Mus. 14889 (type), reversed; Alkali Creek, Buck Spring, 



upper level ol "Big Red Pocket"; Wind River formation, upper part (Wind River B, "Lost 



Cabin"). Contours partly restored from E. borealis. B, E. brownianus, Am. Mus. 4885 (type), 



reversed; Wind River Basin. Contours partly restored from E. borealis and E. princeps. 



Eotitanops- Cory phodon zone (Wind River B), exact 

 level not recorded. 



Specific characters. — Size greater than E. gregoryi; 

 P2-m3, 90 millimeters; mi_3, 55; fang of pi placed in 

 close proximity to the canine; p2 compressed, hypo- 

 conid distinct, elevated, entoconid invisible, paraconid 

 and rudimentary rectigradations placed very low on 

 the crown, metaconid extremely rudimentary if pres- 

 ent; metastylid rudimentary. 



P2 (see fig. 246) is in a less advanced stage of 

 evolution than ps in E. gregoryi. 



As shown in the comparative series of the jaws 

 (fig. 231), in the table of measurements (p. 290; see 

 also fig. 483), and in the accompanying figures, the 

 type of this species belonged to an animal in size 

 midway between E. gregoryi and E. borealis. The 

 ramus of the jaw rather resembles that of E. borealis 

 but with a pronounced swelling below ms; its vertical 

 depth below the anterior face of ms is 40 millimeters; 

 the symphysis is decidedly broad and massive. 

 Eotitanops borealis (Cope) 

 Cf. Palaeosyops borealis Cope 

 Plate LIV; text figures 10, 28, 29, 102, 143, 219, 229-231, 243, 



244, 246, 248-251, 405, 406, 482, 493-495, 497, 498, 501-503, 

 507, 515, 521-523, 646, 648, 649, 690, 694, 700, 

 / 701, 717, 721, 724, 725, 745 



(For original description and typa references see p. 168] 



Type locality and geologic Twrizon. — 

 Wind River Basin, Wyo.; Wind River 

 formation, Lambdotherium- Eotitanops- 

 Coryphodon zone (Wind River B, "Lost 

 Cabin"). 



Specific characters. — Of larger size; p2-m3, 

 94-98 millimeters; premolar teeth more 

 complicated, as shown in neotype and 

 associated specimens; p2 with very, rudi- 

 mentary paraconid and metastylid; p^~* 

 with progressively developing tritocones 

 and single internal deuterocones back- 

 wardly inclined, crowns sub triangular; 

 m'~^ with distinct protoconules. 



Materials. — The fragmentary type speci- 

 men is the historical Palaeosyops borealis 

 (Am. Mus. 4892) of Cope, figured in the 

 "Tertiary Vertebrata," Plate LVIII, A, 

 Figures. It is marked No. 16 in the Wind 

 River valley collection of J. L. Wortman, 

 July, 1880. The very fine specimen se- 

 lected as a neotype (Am. Mus. 14887, figs. 

 250, 251) consists of the skull and jaws 

 found by Granger in 1909 on Dry Muddy 

 Creek, 100 feet above the alkali "red 

 stratum," and represents a slightly larger 

 and somewhat more progressive mutation. 

 Incisors of neotype. — The incisors show the char- 

 acteristic titanothere feature of increase in size from 

 i' to i^, the transverse measurement of the crowns 

 being respectively i' 6 millimeters, i^ 6, i^ 8 (estimated). 

 The crowns of i' and i^ are bluntly spatulate or chisel- 

 shaped. P has a faint antero-internal cingulum; i^ 

 is rounded and subcaniniform. The general arrange- 

 ment of the series is obliquely anteroposterior rather 

 than transverse. The canine is prominent, laterally 

 compressed, the alveolus measuring, transverse, 13 

 millimeters (estimated); anteroposterior, 17. 



