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 genus 

 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, E., " Deer of all Lands," p. 245. 



