EVOLUTION OF ELEPHANTS 



331 



belongs to the Mediterranean sub-region of Holarctica, not to 

 the region of Ethiopia. The centre of dispersion may have 

 been southern Asiatic in the later Tertiary, this centre 

 moving northward after the spread of the elephant into 

 northeast Africa. The following table is given by Dr. 

 Matthew to illustrate the distribution of the Proboscidea.* 



PERIOD NETROPICAL NECABTIC PAL^EARCTIC ETHIOPIAN ORIENTAL 



Recent None None None Loxodon Elephas 



Pleistocene Dibelodon 



Elephas 

 Mastodon 



Elephas 

 Mastodon 



Elephas 

 Trilophodon 



? 



Pliocene None 

 Miocene None 



Dibelodon 

 Trilophodon 



Elephas 



Mastodon 



Tetralophodon 



Trilophodon 



Dinotherium 



(No record) 

 Dinotherium 



Stegodon 



Tetralophodon 



Trilophodon 



Dinotherium 



Oligocene None 



None 



None 



Palseomastodon Hemimastodon 

 Moeritherium Dinotherium 

 ? Moeritherium 



Eocene None 



None 



None 



Moeritherium 



(No record) 



The duration of the "Age of Mammals" has been esti- 

 mated by various geologists as being from 3,000,000 to 

 6,380,000 years and even longer. Wallace's estimate of 

 1881 was 4,200,000 years. This covers the Tertiary (Eocene, 

 Oligocene, Miocene, Pliocene) and the Quaternary (Pleis- 

 tocene, Recent) periods; 4,000,000 years are assigned to the 

 former and 200,000 years to the Quaternary. This last 

 period, however, is estimated by Penck to cover from 

 500,000 to 1,000,000 years. Of the prehistoric Magdalenian 

 period, to which is assigned the remarkable etching of a 

 mammoth on a piece of ivory, Penck estimates that it lasted 

 approximately from 22,000 to 14,000 B.C.f 



*W. D. Matthew, "Climate and Evolution," Annals of the New York Academy ol 

 Sciences, Vol. XXIV, pp. 171-318; New York, February 18, 1915. See p. 255. 



tHenry Fairfield Osborn, "The Age of Mammals in Europe, Asia, and North America," 

 New York, 1910. pp. 63, 385. 



