566 EOCENE AND OLIGOCENE PERIODS 



Vegetation 



In plant history the Eocene was not the dawn of the recent, 

 for the change from medieval to modern plants took place in the 

 Comanchean period. The Eocene did not even mark any radical 

 innovation. There was, however, much progress toward living 

 species, and toward present adaptations of plants to climate, soil, 

 and topography, and to each other. 



Among the plants of the earliest known Tertiary flora of Europe 

 were oaks like those of the present high lands of warm temperate 

 zones. With them were willows, chestnuts, laurels, etc., which 

 have been likened to the flora of southern Japan. The flora of the 

 Denver beds (p. 539), contains figs, poplars, laurels, magnolias, and 

 many ferns. The early Eocene flora of southern Canada included 

 similar forms, together with oaks, beeches, etc., a flora indicating a 

 temperate climate. 



The Middle Eocene of England records a flora "the most 

 tropical in general aspect which has yet been studied in the north- 

 ern hemisphere," l while a later flora "suggests a comparison of its 

 climate and forests with those of the Malay Archipelago and tropical 

 America." The mid-Eocene of America in temperate latitudes 

 contains palms and bananas, mingled with many other trees of 

 similar climatic significance. The Eocene flora of Alaska indicates 

 a climate comparable to that of Southern California and Florida. 

 This flora shows a curious commingling of Jurassic and Cretaceous 

 types (cycads), with angiosperms. A similar flora in the island of 

 Saghalien indicates land connection between Alaska and Asia. 2 



Early Eocene Mammals 



The mammals of the earliest Eocene included several poorly 

 differentiated groups, in which existing orders were foreshadowed 

 rather than represented. The herbivores were foreshadowed by the 

 Condylarthra,a,ndthe carnivores by the Creodonta; but the two groups 

 were not sharply differentiated. Both were five-toed plantigrades, 

 whose phalanges had horny coverings that were neither hoofs nor 

 claws. Edentates, insectivores, rodents, and lemuroids seem to have 

 been represented or foreshadowed. Evolution was so rapid that 

 before the close of the Eocene, most existing groups of mammals 

 were well defined (p. 686). None of the present genera, however, 



1 Geikie, Textbook of Geology, 3d ed., p.' 974. 

 2 Hollick, Am. Jour. Sci., Vol. 31, IQII, pp. 327-30. 



