110 
ORIGIN OF LIFE IN AMERICA 
northern hemisphere, and that they are comparatively modern 
immigrants into South America, where they now attain their 
maximum development. 
Mr. Lydekker gets over the difficulty of the simple-antlered 
South American deer, or brockets as they are called, by the 
admission that because they are unknown in North America, 
they are not ancestral forms. He thinks they should be 
regarded as degraded or arrested types of the group (p. 296). 
Professor Marsh * * * § was inclined to look upon the North 
American Leptomeryx as the probable progenitor of the 
Cervidae. His suggestion led to further researches on the 
part of Dr. Matthewf who supplied a connecting link in the 
chain of ancestry of Odo,coileus in the Miocene Blastomeryx. 
That Dr. Matthew’s view, however, is not generally accepted 
may be gathered from Professor Osborn’s $ recent remark in 
reference to the Pleistocene Period in North America, that 
among the newly entering northern forms are Odocoileus, 
Ursus and Erethizon. Professor Osborn’s § opinion is that 
the origin of the Cervidae will probably prove to be Asiatic. 
I quite concur in the view that they are of Old World origin, 
and yet I hold that the ancestors of the North American 
Odocoileus have invaded the northern continent from South 
America. The remote ancestors of Odocoileus must, there¬ 
fore, have penetrated from the Old World to South America 
without attaining North America. How they have done so is 
the problem I shall endeavour to solve. 
Later on, when we come to deal with the zoogeographical 
relationship of South America and Africa, I shall show that 
we possess valuable evidence for the belief in a former land 
connection across the southern Atlantic between these conti¬ 
nents. This, however, will not help us in explaining the deer 
problem, because no deer have ever been found fossil in Africa 
south of the Sahara, and those species which have succeeded in 
establishing themselves in northern Africa have clearly done 
so in recent geological times. Deer are absent from all the 
* Marsh, 0. C., “ Introduction of Vertebrate Life in America,” p. 30. 
t Matthew, W. D., “Osteology of Blastomeryx,” p. 535. 
f Osborn, H. F., “ Cenozoic Mammal Horizons,” p. 8S. 
§ Osborn, H. F., “Ten Years Progress in Palaeontology,” p. 107. 
