906 



EOCENE AND OLIGOCENE TITANOTHERES OF MONGOLIA 



Fauna (1923-1926).— OngmaWj regarded by Berkey 

 and Granger (1923) "as a unit of Miocene age," 

 the fossiliferous uppermost levels [sands and clayey 

 sands] of the Hsanda Gol are now known to be of 

 middle Oligocene age, but it is believed that the for- 

 mation may well extend down at the base to upper 

 Eocene. 



Matthew and Granger (January 18, 1924, p. 5) 

 listed 22 genera and 26 species of Insectivora, Creo- 

 donta, Carnivora, Rodentia, Perissodactyla, and 

 Artiodactyla of the Hsanda Gol formation. Both the 

 Creodonta and the Carnivora are in an Oligocene stage 

 of evolution tending to early Oligocene; the Rodentia 

 appear to be of lower and middle Oligocene age; the 



Haiiai srranlh 

 \:-^-:~J\ graywacke 



. J ~^^Vit'53'^^^■!,V'->~"'T■- 



/,/ .U"i'r r\lrdin Manha 



•Irdin Manha escarpmenf Houldjm escarpmenf^||,^^ pisAsu- 



Sob; pencplanel undraine_d lowland Sobi peneplane und'ralrK 



N 



lowland 

 atos 



^wouuo)iy..,:°i^-; 



Figure 767. — Map and section of the east-central Gobi Desert, showing location 

 of the chief Cretaceous and Tertiary formations discovered in this region 



Iren Dabasu (Upper Cretaceous dinosaur beds), Houldjin (contains middle Oligocene BaluchWierium zone), 

 Irdin Manha (upper Eocene ProtUanotherium grangeri zone), Arshanto (middle (?) Eocene lophiodont- 

 Schlosseria zone). Pang Kiang (Miocene?), Shara Murun (uppermost Eocene ProtUanotheTium mongo- 

 liense zone). The section shows the Irdin Manha formation (upper Eocene) overlying the Arshanto 

 red beds (middle (?) Eocene), which in turn may overlie the lien Dabasu (Upper Cretaceous dinosaur 

 beds); also the Houldjin formation (middle and lower Oligocene) apparently overlying the Arshanto 

 red beds (middle (?) Eocene). After Berkey and Morris, Basin structures in Mongolia, figs. 12, 

 13, 1924. 



The forms taken from the uppermost beds include 

 (op. cit., p. 9) " BalucMtherium, a fine skull nearly 5 

 feet long [BalucMtherium grangeri], and other rhino- 

 cerids; rodents by the hundreds; artiodactyls; insecti- 

 vores; and carnivores." The fossiliferous uppermost 

 beds of this formation or series are termed the Balu- 

 cMtherium grangeri zone. 



Insectivora also appear to be of OHgocene age; one 

 artiodactyl, comparable to certain artiodactyls of the 

 French Oligocene Phosphorites, is a true primitive 

 cervid, Eumeryx. In the perissodactyl hornless rhinoc- 

 eros BalucMtherium grangeri the premolar evolution 

 is more modernized or recent than that of the Indri- 

 cotherium asiaticum Borissiak of Turgai, Turkestan. 



