40 CENOZOIC MAMMAL HORIZONS 



Loomis); the Palseonictidge are represented by doubtfully referred 

 specimens in the Wind River and lower Huerfano; the 3 certainly 

 surviving creodont families are the Mesonychidse, Oxyaenidse, and 

 Hyaenodontidae. The Edentata-Taeniodonta are represented by 

 Stijlinodon; the Tillodontia by Esthonyx. A supposed marsupial, 

 Peratherium coTustocki, is reported by Cope and Loomis. 



Modernized fauna: Among the modernized forms the forest-living 

 primates first deserve notice: (a) Of the animals of larger size the 

 Notharctidse include Pehjcodus, surviving from the Wasatch and con- 

 tinued into the lower Bridger; also Nothardus, a monkey very plen- 

 tiful in the Bridger, now appearing for the first time; (b) the special- 

 ized Anaptomorphidae recur; (c) the doubtful primates Microsyopidae 

 are also found. 



The Rodentia are represented by the rather abundant Paramys and 

 somewhat more rare Sciuravus. Among Insectivora, 3 families are 

 known, namely, Leptictidae (Palxidops) , and the recently referred 

 families Hyopsodontidae and Pantolestidae. The pro-Carnivora- 

 Miacidae, now become more diversified, including the genera Didy- 

 midis, Vulpavus, and Miacis, all found in the Wasatch, w^hich recur 

 here in slightly larger and more progressive forms. These animals 

 resemble the Canidae in dental structure and the Procyonidae in other 

 points. The Bridger genera Viverravus and Oddedes appear here for 

 the first time. 



Of modernized Ungulata-Perissodactyla there are now 4 families. 

 It is noteworthy that all are represented by light-limbed slender- 

 footed forms, pointing to rather dry-land conditions in this region 

 at the time, (a) The Equidae are represented by the persisting 

 Wasatch forms still known as Eohippus because a rudimentary fifth 

 digit still persists in the pes and there is little advance in dentition. 

 (b) Members of the Tapiridae have not been found, but they un- 

 doubtedly existed, (c) The Lophiodontidae are represented by 

 Heptodon. (d) The newly appearing Titanotheriidae are represented 

 ^ by 2 genera and 3 species. 



The distinctive forms of titanotheres found in the Wind River are: 



Lower part of Wind River, Lambdotherium popoagicum, of about the height of a water 



chevrotain (Dorcatherium aquaticum). 

 ?Upper part of Wind River, Eotitanops borealis, of about the height of a wart-hog 



{Phacochcerus africanm). 

 ?Upper part of Wind River, Eotitanops brownianus, of about the height of a young 



pig- 



Of these animals the Lambdotherium occurs plentifully only in the 

 upper Wasatch deposits, in the lower part of the Wind River, and in 

 the Huerfano formation of southern Colorado. Nothing at present is 

 known in the Wasatch which could stand ancestral to it^ nor is any 



