AMERICAN MULE DEER 
109 
which we find living here and there in isolated districts, are 
more ancient in point of origin. 
In South America we have still living at the present 
moment deer of the type of the mule-deer, only smaller, 
with simple forked antlers. Other still smaller deer possess 
merely minute spike-antlers. Extinct deer, moreover, with all 
the different kinds of antlers, have been observed in South 
American Pleistocene and Pliocene deposits. One species 
(Odocoileus avius), which, according to Professor Ameghino, 
belongs to the group with complex antlers, has even been 
noticed in the upper Miocene of Argentina. 
Both fossil and recent evidence thus clearly points to South 
America as the source of these true American deer. If we 
supposed that the ancestors of the North American species 
of Odocoileus had penetrated northward in Pliocene times, 
when Central America assumed its present shape, we should 
have a reasonable explanation for the fact that the genu,s 
has never spread to the peninsula of Alaska, nor into north¬ 
eastern Canada and Newfoundland. 
What prevents the general adoption of the theory of the 
South American origin of this group of deer ? Clearly the 
fact that while the deer family (Cervidae) is represented 
from the Oligocene to the most recent deposits in Europe, 
it only makes its appearance in South America in the upper 
Miocene. The original home of the family is therefore 
believed to be in the northern hemisphere, and this assump¬ 
tion is strengthened by the circumstance that nowhere except 
in South America have deer penetrated to the southern hemis¬ 
phere. Since it is inadmissible to argue that mammals so 
near akin as the Old World and New World deer should have 
appeared quite independently of one another in two distinct 
centres, these affinities can only be explained by migration 
from the one centre to the other. According to most palaeonto¬ 
logists who expressed an opinion on this problem, the South 
American deer could only, for the reasons stated, have entered 
South America from North America. Whether they were 
developed in the Old World or the New, it is evident, remarks 
Mr. Lydekker,* that the American deer originated in the 
Lydekker, R., “ Deer of all Lands,” p. 245. 
