910 



EOCENE AND OLIGOCENE TITANOTHERES OF MONGOLIA 



Menodus mongoliensis, a much larger animal than 

 Brontops, characteristic of a higher geologic level. 



Osborn (October 19, 1923) described Cadurcotlierium 

 ardynense as resembHng Cadurcotherium cayliixi of the 

 Oligoceue Phosphorites of France. The quarry con- 

 taining these rhinoceroses {Cadurcotherium ardynense) 

 lies 200 feet above the Brontops gobiensis level, or 

 100 feet below the top of the mesa, which is protected 

 by a heavy sandstone capping that preserves it from 

 erosion. 



SUMMIT OF THE EOCENE: SHAEA MURUN FORMATION 

 Berkey and Granger (Ma}' 25, 1923, p. 12) 



General features. — A hundred miles south of the 

 Ardyn Obo formation is a distinct basin carrying 

 fossiliferous strata which have been called the Shara 

 Murun formation. The sedimentary area is very 

 large and the best exposures occur along the borders 

 of a 200-foot escarpment. At this place were found 



To Sair Usu 



Dolichorhinus kaiseni 

 Protifanotherium mongo/iei 

 andremsKtypi 



20252 



Dolichorhinus kaiseniftypej 



FiGTjRE 770. — Field sketch of the chief fossiliferous beds of the Shara Murun formation 

 near Ula Usu, on the Kalgan-Uhassutai trail, showing where the types of Prolitano- 

 therium andrewsi, P. mongoliense, and Dolichorhinus kaiseni were discovered 



Unlike the Irdin Manha quarries, the fossihferous locaUties are close together in the Shara Murun formation. 

 After sketch by Walter Granger, chief paleontologist of the third Asiatic expedition. 



titano there remains resembling those found in the 

 Irdin Manha formation early in the season of 1922. 

 These beds are assigned a total thickness of 500 feet. 



The first fossil found in this formation was a titano - 

 there, which Osborn (October 17, 1923, p. 3) identified 

 as ProtitanotJierium mongoliense, a form closely inter- 

 mediate in size and characters between Protitano- 

 tJierium emarginatum and the large Protifanotherium 

 superhum, both of the Uinta formation (horizon C of 

 Uinta Basin) of northern Utah (compare fig. 778). 



According to Granger a total thickness of over 300 

 feet is exposed at this type locality. The fossils are 

 distributed through a vertical thickness of about 150 

 feet; this may account for the presence in the upper 

 levels of Protitanotherium andrewsi, a more progres- 

 sive species than Protitanotherium mongoliense, which, 

 in turn, is much more progressive than the species 

 Protitanotherium grangeri of the Irdin Manha forma- 



tion. The Shara Murun beds near Ula Usu have 

 somewhat the appearance of those of the Irdin Manha 

 formation at the Irdin Manha bench — gray shales 

 above and red shales at the base — but they weather 

 out in deeper gulches. Calcareous concretions are 

 rare in the 150 feet of rich fossiliferous beds. There 

 is much local slipping of the clays, whereby many of 

 the titanothere crania were badly crushed and dis- 

 torted, so that they required careful restoration. 

 The titanothere bones of the Shara Murun are readily 

 N distinguishable by their light 



cream color and softer texture 

 from the rust-brown bones found 

 in the Irdin Manha. 



Fauna. — The fauna of the 

 Shara Murun formation is more 

 recent than that of the Irdin 

 Manha. The small lophiodonts 

 (Desmatotherium) that swarm in 

 the Irdin Manha are rare in the 

 Shara Murun, which carries 

 many larger lophiodonts (Depere- 

 tella) and long-limbed baluchi- 

 therine (?) rhinoceroses (ancestral 

 Baluchitherium?) , as well as 

 numerous Amynodon. The great 

 herds of lophiodonts found in the 

 Irdin Manha are replaced in the 

 Shara Murun by small traguline 

 artiodactyls. These artiodactyls 

 (Archaeomeryx) were found in 

 layers that contained no other 

 mammals and may represent 

 small herds suddenly overcome. 

 The large lophiodonts {Depere- 

 tella) were also found by them- 

 selves, many individuals com- 

 pacted in a small area. 

 The rhinoceroses, which are rare in the Irdin Manha, 

 are fairly abundant in the Shara Murun and are at 

 some places mingled with titanotheres but are gener- 

 ally segregated. They include one complete skeleton 

 of Amynodon in a stage of evolution similar to that of 

 Amynodon antiquus of the upper part of the Bridger 

 formation (horizon B of Uinta Basin) of Utah. Skele- 

 tal remains and jaws and teeth of five very long-limbed 

 baluchitherine (?) rhinoceroses were found, which 

 may prove to be ancestral to the Baluchitherium 

 grangeri of the middle Oligocene. 



The titanotheres of the three species Dolichorhinus 

 Icaiseni, Protitanotherium mongoliense, and Protitano- 

 therium andrewsi dominate all other mammals, and 

 in one quarry (fig. 770) a large deposit of these bones 

 was found and worked by Kaisen during June and 

 September, 1923. In the Shara Murun, as in the 

 upper Eocene " Titanotherium beds" of the Rocky 



To Kolgan 

 Wells 



