OLIGOCENE OF EUROPE, NORTH AFRICA, AND NORTH AMERICA 213 



the varied structure of the horses. Titanotherium, for example, being a 

 slender-hmbed, and swift-moving, animal, may have cultivated a grazing 

 habit, while Brontotherium (Fig. 97) was a heavy-limbed, slow-moving 

 quadruped armed with gigantic horns 

 and teeth of a relatively short- 

 crowned, browsing type. The titano- 

 theres now reach the climax of their 

 evolution and become extinct with 

 apparent suddenness. 



Two members of this^family have 

 been discovered in Europe. They 

 are (1) Brachydiastematherium trans- 



SylvaJliaim from the vicinity of Andra- By permission ot the U.S. Geological Survey. 



shaza Klausenburg, TranSSylvania, in Fig. lOl. — Scale section of the Oligocene 



Hungary, comparable to om Proti- Sa^kSa^'^'lft^rWoVtml^^ 

 tanotherium; (2) 'Titanotherium' ru- 



melicxim Toula, from Bulgaria. Probably a member of the sub-family 

 Titanotheriinae {fMegacerops) . 



The faunal group as a whole is exhibited in the following conspectus: 



Leptauchenia 

 „ clays'" 

 emazone Protoceras 

 sandstones" 



Oreodon clays" 



Me tamynodon 

 sandstones''^ 



Titanotherium 

 clays and 

 one sandstones" 



Characteristic 

 Mammals 



Opossums 



Leptictids 



Hyaenodonts 



True canids 



Mustelids 



Machaerodont cats 



Surviving Eocene rodents 



(ischyromyids) 

 Hcteromyids 

 Leporids (hares) 

 Hyracodonts 

 Amynodonts 

 Aceratheres 

 Diceratheres 

 Lophiodonts 

 Horses 



Clialicotheres 

 Titanotheres 

 Entclodonts 

 Dicotylids 

 Lpptochrcrids 

 Anthi'acotheres 

 Camels 

 Hypertragulids (hornless) 



This group seems to be much richer in peris- 

 sodactyls than that of the Lower Oligocene of 

 western Europe, especially in the presence of the 

 cursorial rhinoceroses or hyracodonts, of the 

 horses, of surviving slender-limbed lophiodonts 

 (Colodon), as well as of the great titanotheres. 

 Beside the hyracodont and amynodont rhinoc- 

 eroses the true rhinoceroses appear, probably 

 both the acerathere and dicerathere ancestors, 

 distinguished (Trigonias) by the presence of 

 small upper canine teeth. Coenopus is a still 

 more common form. We note that the artio- 

 dactyls are freshly allied to those of Europe 

 through the widespread anthracotheres (Ancodus f 

 Anthracotherium) , probably recent arrivals from 

 the Old World. The primitive peccaries (Dico- 

 tylidae), the primitive ruminants (Hypertra- 

 gulids), and the small camels (Camelida?) are 

 peculiarly American. Primitive insectivores (lep- 

 tictids and chrysochloritls) occur. The opos- 

 sums (Peratherium) survive. The Carnivora- 

 Creodonta now include a variety of hyjenodonts, 

 among which are forms of really gigantic size. 

 The true Carnivora include varied canids 

 (Daphcenus and Cynodidis), the latter similar 



