224 



TITANOTHERES OF ANCIENT WYOMING, DAKOTA, AND NEBRASKA 



Titanops Marsh, 1887 



Cf. Brontolherium, this monograph, page 555 

 Original reference. — Am. Jour. Sci., 3d ser., vol. 34, 

 p. 330, October, 1887 (Marsh, 1887.1). 



Type species. — Titanops curtus. (See below.) 



Figure 182. — Type (holotype) skull of Titanops curtus 

 Front view. Yale Mus. 12013. After Marsh, 1887. One-eighth natural size. 



Generic characters. — Marsh writes: 



This genus contains the largest members of the Brouto- 

 theridae and some of the last survivors of the group. They are 

 distinguished from all the other known types by the long, 

 narrow skulls, lofty, flat horn cores, and short nasals. The 

 upper dentition corresponds nearly to that of Brontotherium, 

 but the upper molars have all two inner cones. * * * The 

 nasals are the shortest known in the group. 



Etymology. — Titanotlierium; u^/, face — that is, like 

 Titanotlierium. 



Present determination. — The genus is a synonym of 

 Brontotherium Marsh. 



Titanops curtus Marsh, 1887 



Cf. Brontotherium curtum, this monograph, page 574 



Original reference. — Am. Jour. Sci. 3d ser., vol. 34, 

 p. 330, fig. 11, October, 1887 (Marsh, 1887.1). 



Type locality and geologic horizon. — Colorado; e.xact 

 locality not stated but recorded by Hatcher (1901) as 

 from the upper Titanotlierium zone [of Chadron 

 formation]. 



Type. — A complete skull with teeth (Yale Mus. 

 12013). (See fig. 182.) 



Specific characters. — Not separated from generic 

 characters by Marsh. 



Etymology. — curtus, short; in allusion to the short 

 nasals. 



Present determination. — The species is valid and is 

 referred to Brontotherium. 



Titanops elatus Marsh, 1887 

 Cf. Brontotherium gigas, this monograph, page 567 

 Original reference. — -Am. Jour. Sci., 3d ser., vol. 34, 

 p. 330, fig. 12, October, 1887 (Marsh, 1887.1). 



Type locality and geologic horizon. — "Upper Titano. 

 therium zone, South Dakota" (Chadron formation). 



Type.— A skull and jaw (Yale Mus. 12061). (See 

 fig. 183.) 



Specific characters. — Marsh writes: 



The nasals are much longer, and the occipital crest much 

 higher, than in the type species [T. curtus]. The zygomatic 

 arches are unfortunately wanting, but the lower jaw is present, 

 nearly in place. It shows no marked characters different 

 from that of Brontops. 



Etymology. — elatus, lofty; possibly in allusion to the 

 high stage of specialization. 



Present determination. — The species is synonymous 

 with Brontotherium gigas Marsh. 



Allops Marsh, 1887 



Cf. Allops, this monograph, page 506 



Original reference. — Am. Jour. Sci., 3d ser., vol. 34, 

 p. 331, October, 1887 (Marsh, 1887.1). 



Type species. — Allops serotinus. (See below.) 

 Generic and specific characters. — Marsh writes: 



This skull in its general form resembles that of Brontotherium, 

 but differs in having only a single upper incisor, and the last 

 molar has the posterior inner cone more strongly developed. 



The superior dentition is as follows: Incisor, 1; canine, 1; 

 premolars, 4; molars, 3. 



In the tj'pe specimen the canine is small, extending but 

 httle below the premolars. There is no diastema. The upper 

 premolars have a very strong inner basal ridge. The nasals 

 are wide, expand forward in the free portion, and are notched 

 in front. The entire length of the skull is 31 inches (79 centi- 

 meters), the distance across the zygomatic arches 21 inches 

 (53 centimeters), and the length of the horn cores about 10 

 inches (25 centimeters). 



Figure 183. — Type (holotype) skull of Titanops elatus 

 Front view. Yale Mus. 12061. After Marsh, 1887. One-eighth natural size. 



Etymology. — aXXos, strange; ciiA, face. 



Present determination. — Allops is intermediate be- 

 tween Menodus and Brontops and is here regarded as 

 a valid genus. (See p. 506.) 



