SUCCESSIVE MAMMALIAN FAUNAS 221 



In size, these creatures varied from a tapir to an elephant, 

 though all were much shorter-legged than any elephant ; the 

 extremely massive tail, which the larger forms had, served to 

 support the huge body, when erected to tear down the branches 

 and leaves upon which these strange creatures fed. 



Opossums were extremely numerous, especially in the 

 Brazilian caves, where in half a cubic foot of earth 400 jaws 

 were collected. 



The Pleistocene mammalian fauna of South America was 

 a mixture of modern forms with ancient, vanished types similar 

 to that which we found in North America. The fground- 

 sloths and jglyptodonts, the jlitopterns, ftoxodonts and 

 ftypotheres, the antelopes, horses and fmastodons have all 

 disappeared from the continent, or vanished altogether from 

 the face of the earth. 



II. Tertiary Faunas 

 1 . Pliocene 



North America. — No part of the Cenozoic history of North 

 America is so imperfectly recorded and so unsatisfactorily 

 known as that of the Pliocene, and the later portion of that 

 epoch is especially obscure. If the Peace Creek formation 

 of Florida is properly referred to the upper Pliocene, it would 

 show that the mammals of that time were substantially the 

 same as those of the eai'ly Pleistocene. 



The only fauna, as yet discovered, which can be referred 

 to the middle Pliocene, is that of the Blanco beds of north- 

 western Texas, which have yielded but a scanty list of mostly 

 ill-preserved fossils. Obviously, these give us a very incom- 

 plete picture of the life of that time. The great fground- 

 sloths had already reached North America, and the genus 

 ^Megalonyx, so common in the forested areas of Pleistocene 

 North America, was perhaps already in existence. The 

 tglyptodonts were likewise represented by one genus {\Glyp- 



