ENVIRONMENT OF THE TITANOTHEEES 



95 



of Cuvier. The lower Ludian yielded the type speci- 

 men of the equine LophiotJierium, a horse in the same 

 stage of evolution as the diminutive American Epihip- 

 pus of the Uinta. The American beds contain a rich 

 titanothere fauna. They include the "Diplacodon 

 beds" of Marsh (1877.1, p. 354) and contain the 

 robust titanothere Protitanotherium, which is inter- 

 mediate between the "prophet-horn" Manteoceras and 

 the horned titanotheres of the lower Oligocene; also the 

 type of Protitanotherium superbum, an animal greatly 

 exceeding in size the earlier Oligocene titanotheres. 

 Of great interest is the survival of the ancestral genus 

 Manteoceras in the species M. uintensis, a genus first 

 occurring in the upper Bridger, and the Bridger genus 

 TelmatJierium in the species T. ultimum. 



plains fauna (Hypertragulidae and Camelidae) rep- 

 resented respectively by genera believed to be ancestral 

 to the tragulids (Leptotragulus) and to the camels 

 (Protylopus, Camelomeryx) ; also members of the 

 oreodonts (Protoreodon), and the agriochoerids {Agrio- 

 choerus). The diminutive tylopod Protylopus has 

 been selected as the possible ancestor of the great 

 family of American camels. 



The fauna found near the base of the true Uinta 

 thus includes a considerable light-limbed meadow 

 and plains element, transitional to the plains fauna 

 of the lowest Oligocene of the White River group. 

 The occurrence of this fauna near the base of Uinta 

 C indicates that the Uinta formation probably passes 

 up into lower Oligocene time. The beds represent 



Figure 66. — Badlands near the mouth of White River, Uinta Basin, Utah (No. 10, fig. 35) 



Wortman and Peterson collecting. This view shows the typical Uinta formation (Uinta C 1) and the Diplacodon zone in the fore- 

 ground, with Uinta C 2 (unfossiliferous) in the distance. After Osborn (1910.346). Am. Mus. negative 17663. Compare Plate 

 XII, B. 



The amphibious rhinoceros Amynodon occurs in the 

 species A. antiquus. It should be noted that the 

 remains of all these large mammals were found not 

 far above the base of Uinta C, and that all the speci- 

 mens in the chief collections of small Artiodactyla 

 (Protoreodon, Leptotragulus) and of Perissodactyla 

 (Triplopus, LopModon, Isectolophus , a tapiroid, Epi- 

 Jiippus) (Peterson) were obtained from the lower 

 levels of Uinta C. With Epihippus were found the 

 only primate that has been discovered in the Uinta 

 Basin, NotJiarctus? uintensis, a lemuroid, and the 

 supposed condylarth or insectivore Hyopsodus. The 

 few surviving ancient creodonts are represented by 

 Oxyaenodon and by the giant Harpagolestes uintensis. 

 Especially important is our first knowledge of the 



a considerable change in local physiographic condi- 

 tions from those of Uinta B. The fine-grained soft 

 material, composed of altered eruptives, probably 

 dacite tuffs, is of much the same texture as the char- 

 acteristic " Titanotherium beds" (Chadron formation) 

 of South Dakota, except as to its color, which is brick- 

 red ; in fact, a reddish tinge prevails throughout the 

 sediments of Uinta C 



During this latest part of the Eocene epoch the 

 titanotheres of the Rocky Mountain basin south of the 

 Uinta Mountains distinctly approach in character the 

 titanotheres of the Great Plains. The appearance 

 in this layer and near the summit of Uinta B of two 

 or three entirely new forms of titanotheres (Eotitano- 

 tJierium, Diplacodon, Protitanotherium) is less indica- 



