THE PLIOCENE OF EUROPE, ASIA, AND NORTH AMERICA 311 



frequent, and when present include only those with simple antlers like the 

 roe deer (Capreolus). Among the rodents are two forms (Trilophomys and 

 Ruscinomys) allied to the African crested rats. A flying squirrel {Sciurop- 

 terus) and a primitive beaver (Chalicomys) persist from the Miocene. 

 Further details regarding this older fauna are given below in the descrip- 

 tion of the mammals of Roussiilon. At Casino are recorded the newly 

 arriving hippopotami (p. 313). 



The newer Pliocene fauna^ witnesses the disappearance of the last of 

 the characteristic Miocene genera, among which only the mastodon sur- 

 vives until the close. The horse {Equus stenonis) replaces Hipparion; the 

 Bovinse appear in Europe for the first time {Leptobos elatus) ; monkeys con- 

 tinue in Italy, but are now represented by forms {Macacus florentinus) allied 

 to the Barbary macaque of Gibraltar; the southern elephant (Elephas 

 meridionalis) makes its appearance and coexists almost everywhere with 

 Mastodon arvernensis and M. borsoni. This fauna has been found in vari- 

 ous parts of Italy, France, and England. Not the least characteristic 

 feature of this newer fauna is the abundance of large deer with elaborate 

 antlers of the 'polycladine' tyi3e, as well as ancestors of the true Cervus or 

 ' elaphine ' type. The newer fauna of the Upper Pliocene is thus sharply 

 defined by the expulsion or emigration of many of the resident Asiatic or 

 African forms, and by the sudden introduction or appearance of several 

 modern types which had probably evolved in North America, Asia, and 

 possibly Africa, chief among which are the following animals: 



Equus (E. stenonis) the true horses North America 



Leptobos (L. elatus) the first true cattle Southern Asia 



Cervus (C. dicranius), etc., polycladine deer Northern Asia 



Elephas (E. ineridionalis) the true elephants Asia or Africa 



Summary. — Comparing this with the corresponding general history of 

 Miocene life, p. 249, we observe that the Pliocene migrations and extinctions 

 exactly reverse those of the Miocene. 



The explanation of this interesting contrast is to be found in the reversed 

 order of the physiographic changes in Europe, and of the changes in plant 

 life, p. 244. In other words, while the Miocene closed with a period of 

 warm, dry, open plains in southern Europe favorable to grazing or steppe 

 types, the Pliocene closed with a moister period and the spread of forest and 

 fluviatile conditions interspersed with meadows favorable to a great vari- 

 ety of browsing deer, as well as to the grazing elephants, horses, and cattle. 



Lower Pliocene or Plaisancian 



As this is chiefly a marine phase, the terrestrial mammalian fauna is 

 imperfectly known. The typical deposits are those of the lignites of 



' Deperet, Succession stratigraphique des Fauiies dc Mamiuif^res Pliocenes do rEurope. 

 1893, p. 539. 



