94 THE AGE OF MAMMALS 



cult to draw conclusions from fossil plant remains alone as to their relative 

 or absolute importance. At what period grasses began to assume anything 

 like their present dominance it is impossible to determine. The absence of 

 native grasses in Australia is indirect evidence of their late geological devel- 

 opment. According to Schimper and Schenck ' the first record of grasses 

 is in the Cretaceous Age, the cane {Arundo), and the reed (Phrag mites) 

 being found in North America. According to Gardner - the determination 

 of the meadow grass (Poacites) from the Kome beds of Greenland is very 

 doubtful. There can be little doubt, according to Hollick, that grasses arose 

 at an early period in the Csenozoic, perhaps even in the lowest Eocene. 

 While Gardner (1886, p. 454) considers that they attained prominence in both 

 hemispheres only toward the close of the Eocene, he believes it to be not im- 

 probable that they were established in the north (Spitzbergen) at an early 

 period. The indirect evidence derived from the adaptations of the teeth of 

 mammals disposes us to adopt the opinion of Gardner (1886, p. 441) that 

 grasses attained wide distribution in both hemispheres only toward the close 

 of the Eocene. Their evolution on favorable forestless regions was certainly 

 a very prolonged one, beginning in Mesozoic times. 



A southern flora. — The Tertiary flora in general ^ represents not only 

 every one of the great types of vegetation but also a large niunber of the 

 orders and genera of the present plant world. Passing over from the Creta- 

 ceous into the early Tertiary, the horsetails (Equisetaceae) are represented by 

 reduced forms. Among the gymnosperms, the cycads were waning while the 

 Coniferae, or true gymnosperms, were represented by forms closely allied to 

 the sequoias, widely distributed and in great abundance. The true conifers 

 or pines were of more modern origin. The palms were a dominant tyi^e 

 which flourished in great luxuriance during the Eocene and Miocene. The 

 dicotyledonous angiosperms which had appeared suddenly in the Upper Cre- 

 taceous began to gain complete ascendancy, and in this group were several 

 types which seem to be waning at the present time : for example, the sassa- 

 fras (Sassafras), tulip tree {Liriodendron) , and the sweet gum (Liquidambar) . 

 In the Eocene a luxuriant vegetation covered the northern hemisphere as far 

 north as Grinnell Land (81° 45") ; the Arctic flora alone comprising 400 

 species of arborescent type. In North America the deciduous flora of the 

 older Cajnozoic was very similar to the modern flora. 



The processes of modification and evolution of plants were far slower 

 than the evolution of mammals. In connection with what has been said 

 above regarding grasses, it is important to note that the deciduous plants 

 which we know are mainly those which grow in the lowlands. In Caenozoic 

 times, as now, there was a great difference in the vegetation of different 



' Schimper und Schenk, Handbuch der Palilontologie (Zittel), II Abth., Palaophytologie, 

 1890, p. 385. 



2 Gardner, J. S., Fossil Grasses. Proc. Geol. Assoc, Vol. IX, 1886, p. 441. 



^ Ward, L., Plants, Fossil, in Johnson's Universal Encyclopiedia, 1895, p. 329. 



