128 



TITANOTHEEES OF ANCIENT WYOMING, DAKOTA, AND NEBRASKA 



together in the same region in the West. In Miocene 

 time the American rhinoceroses were joined in the 

 western plains by certain European rhinoceroses. 

 Thus continental radiations from great countries like 

 Africa, Asia, or America may pour some of their 

 branches into a single small region, mingling many 

 distinct phyla. 



Hypsodont or grazing types may mingle with brach- 

 yodont or browsing types in the same locality through 

 their choice of grasses or of shrubs as their principal 

 article of diet. Independently in the same region in 

 southern Wyoming two of the branches of the titano- 

 theres {Telmatherium and DolichorTiinus) began to 

 acquire long-crowned teeth, while two others {Palaeo- 

 syops and Limnohyops) retained persistently short- 

 crowned teeth. 



HABITS OF THE EHINOCEROSES PARALLEL TO THOSE OF 

 THE OLIGOCENE TITANOTHERES 



Mingling of hrowsing and grazing rJiinoceroses in 

 Africa. — In equatorial Africa the Nile is an insuperable 

 barrier between two species of rhinoceros, the "white 

 rhinoceros," which is confined to the west bank, and 

 the "black rhinoceros," which ranges along the east 

 bank; yet these two species were formerly found 

 together in the same regions of South Africa. The 

 large grazing "white rhinoceros," R. (Ceraiotheriwn) 

 simus, has hypsodont teeth and grazes in the open 

 country, particularly in the wide, grassy valleys, 

 though it was frequently met on the high veldt of 

 Matabele and Mashonaland, feeding at night or in the 

 cooler parts of the morning and evening. Its food 

 consists entirely of grasses. Its sight is bad, but its 

 scent and hearing are acute. On the other hand, the 

 smaller browsing "black rhinoceros," R. (Opsiceros) 

 hicornis, which has brachyodont teeth, was formerly 

 common on the slopes of Table Mountain and on the 

 Cape Flats and closely overlapped R. (Ceratotherium) 

 simus in certain parts of its range; it frequented bush- 

 covered country more than open grass lands and was 

 often found in rocky, stony districts. It is partly 

 nocturnal in its habits. Its food consists entirely of 

 leaves, twigs, and sometimes of the roots of certain 

 bushes and shrubs, but seldom of grass (Roosevelt and 

 Heller, 1914.1). Its adaptations are essentially those of 

 a browser, for it prefers the twigs and small roots of 

 certain shrubs which it finds on the treeless plains of 

 East Africa (Stevenson-Hamilton, 1912.1). It has a 

 considerable vertical geographic range,'- being found 

 also on the high plateau near the glaciers of Mount 

 Kenya. (J. W. Gregory, 1896.1, p. 267.) 



Habits of Asiatic rhinoceroses. — The existing species 

 of Asiatic rhinoceroses differ in habitat; they do not 

 mingle. Rhinoceros unicornis or indicus, which has 

 relatively hypsodont grinders, frequents the swampy, 

 grassy jungles of the plains of India. The R. sondaicus 



" Gregory attributes this range to the white rhinoceros, but his observation 

 actually refers to the black rhinoceros, as Heller has pointed out. 



of Burma and Java has shorter grinders. As observed 

 by Blanford (Lydekker, 1893.1, vol. 2, sec. 4, p. 

 470), it "is more an inhabitant of the forest than of 

 the grass, and although it is found in the alluvial 

 swamps of the sudarbans, its usual habitat appears 

 to be in hilly countries. It has been observed at 

 considerable elevations both in Burma and Java." 

 Indeed there is much evidence that it probably ascends 

 occasionally to as much as 7,000 feet above sea level. 

 Its food consists largely of twigs and smaller branches. 

 The third species of Asiatic rhinoceros, the Sumatran 

 rhinoceros {R. (Dicerorhinus) sumatrensis) , which has 

 relatively short-crowned teeth, inhabits hilly forest 

 districts and has been observed in Tenasserim at an 

 altitude of 4,000 feet above the sea. According to 

 Lydekker, it is a good swimmer and is said to have 

 been seen swimming in the sea in the Mergui Archi- 

 pelago, possibly traveling in search of new feeding 

 grounds or to avoid certain unfavorable conditions. 



Thus we find among the rhinoceroses three lines of 

 adaptation to habitat and to food radiation — first, both 

 hypsodont (grass-loving) and brachyodont (browsing) 

 forms; second, a considerable geographic vertical range 

 both in R. (Ceratotherium) simus and R. sondaicus; 

 third, the occasional assumption of semiaquatic habits. 



All these conditions were partly paralleled among 

 the Oligocene titanotheres, which, however, attained 

 no extreme hypsodontism. 



HABITS OF THE EXISTING TAPIRS PARALLEL TO THOSE OF 

 THE EOCENE TITANOTHERES 



The Eocene titanotheres, although inferior in the 

 structure of their grinding teeth, were nearest in form 

 and in body adaptations to the existing tapirs. In 

 the Tapiridae we find these principles of adaptive 

 radiation — great vertical geographic range, including 

 choice between upland and lowland habitat, and 

 assumption of more or less aquatic life. The teeth 

 are short-crowned (brachyodont), are crested (lopho- 

 dont), and are superior in mechanism to the cone and 

 crescent (bunoselenodont) grinders of the titano- 

 theres. These principles are observed as follows: 



1. According to J. E. Gray (1872.1, p. 486) Tapirus 

 pincJiaque ascends to very great heights in the Andes. 

 M. Goudot "obtained a young female tapir at an 

 elevation of about 1,400 meters — nearly up to the 

 snow level on the Peak of Tolima in New Granada — 

 about 1843." According to Gray (1872.1, pp. 487, 

 488) Tschudi, in the "Fauna peruana" (p. 213), says, 

 " This species of tapir [T. roulini] is found in Peru on 

 the eastern slope of the Cordilleras at an elevation of 

 7,000 or 8,000 feet, which is above the snow line. " 



2. On the other hand, the tapirs (T. hairdi) from 

 Mexico and the Isthmus of Panama, which have 

 been referred to the genus Elasmognathus by Gill, are 

 more generally confined to the lower hills or occupy 

 an intermediate habitat. Captain Dow observes 

 (1867.1, p. 214): 



