THE EOCENE OF EUROPE AND NORTH AMERICA 147 



Cuvier, are slender and slightly formed, like the most beautiful gazelles. 

 For the environment of these animals Cuvier pictured a small number of 

 tolerably fertile plains wherein they could multiply, perhaps separated by 

 considerable stretches of lofty hills. The researches of Adolphe Brongniart ^ 

 revealed the flora of the period as consisting of palm trees and many other 

 beautiful plants, while in the waters were found crocodiles and soft-shelled 

 turtles (Trionychia). 



The following is a newer picture of the Upper Eocene life of southern 

 France, England, and Bavaria. 



Herbivorous mammals. — The odd-toed ungulates, or perissodactyls, 

 become increasingly important. All are polyphyletic, or broken up into a 

 number of independent phyla. (1) The lophiodonts, the dominant family, 

 embrace two main generic phyla {Lophiodon and Chasmotherium) , both 

 descended from Ypresian ancestors, and both becoming extinct in the 

 Bartonian; of these the genus Lophiodon splits up into three sub-phyla, 

 according to Deperet. (2) The palseotheres, first known in the Upper 

 Lutetian, also diphyletic and including the cursorial Plagiolophus and the 

 less swift but bulkier Palceotherium, were of medium size; they become 

 extinct in the Ludian. (3) The hyracotheres, or primitive horses, also 

 sulidivided into three and perhaps four phyla (Pachynoloplms, Anchilophus, 

 Lophiotherium), were of the smallest size and greatest speed. They ap- 

 parently disappeared from western Europe at the close of the Ludian. 



The even-toed ungulates, artiodactyls, though inferior in size to the 

 largest of the perissodactyls, were highly varied and numerous, yet appar- 

 ently not ancestral to any of the modern artiodactyls. They include: 

 (1) The dichobunes, sub-selenodont artiodactyls of very small size, similar 

 to the homacodonts of North America. This is a prominent Eocene phylum 

 which extends into the Oligocene (Stampian), but according to the best 

 authority (Stehlin) does not give rise to the higher artiodactyls or rumi- 

 nants.- (2) Anthracotheres of somewhat larger size, but swift-moving 

 cursorial forms, first appear in the Lutetian (Catodontherium) , and des- 

 tined to survive into the Oligocene (Brachyodus), to become dominant in 

 size and variety and to send off branches which migrated to North America. 



(3) Xiphodonts, excessively light-limbed, fleet, or cursorial forms first 

 know7i in the Lutetian, surviving to the close of the Eocene (Ludian). 



(4) Dichodonts and dachrytheres, first appearing in the Upper Lutetian 

 and surviving to the close of the Eocene. (5) Anoplotheres, browsers, 

 forest and swamp dwellers, of larger size, slow-moving, with clumsy feet, 

 first appearing in the summit of the Eocene (Ludian). (6) Aberrant 



1 Cuvier, G., and Brongniart, A., Description Geologique des Environs de Paris. Paris, 

 1821. 



- See Stehlin, Die Siiugetiere des schweizerischcn Eociins. Critischer Catalog der Materia- 

 lien. Abhandl. schweiz. palaont. Ges., Vol. XXXIII, Zurich, 1906, Pt. 4, p. 670 (table of the 

 phylogeny of the dichobunids). 



