LIFE 493 



islands north of the mainland. The Trias here is generally con- 

 formable on the Permian and beneath the Jurassic. 



In South America no marine deposits of Triassic age are known 

 ea>t of the Andes, but coal-bearing Trias occurs in Argentina and 

 Onle, and marine beds at various points in the Andes. Thus it 

 is clear that the site of parts of this great system of mountains was 

 beneath the sea in the Triassic period. 



The Triassic system is represented also in South Africa, Aus- 

 tralia, New Zealand, and New Caledonia. 



LIFE 



The remarkable physical conditions that impoverished the land 

 life of the Permian period held sway during the early part of the 

 Triassic, and the two periods were much alike in their general 

 biological aspects, as in their physical conditions; but toward the 

 close of this period there was a pronounced change. The land 

 became lower and the sea encroached upon it, bringing about appro- 

 priate changes in life. Nearly all that is known of life in North 

 America belongs to the later portion of the period. 



Plants. Plant life was probably meager, for broad saline basins 

 and arid tracts are inhospitable to it. At any rate, its record is 

 scanty. The Triassic was distinctly an age of gymnosperms. Ferns 

 and fern-like plants were still important but their dominance was 

 past. The great lycopods, too, were almost gone, though sigillarias 

 were among their lingering representatives. Calamites had given 

 place to true equiseta, which were represented by gigantic forms. 

 Among gymnosperms, cordaites had declined, and ginkgos (Gink- 

 goales) diverged from them at about this time. Conifers of the 

 types that came in during the Permian, and kindred new ones, were 

 prominent. The cycadean group (p. 685) occupied the place of 

 central interest. The Bennettitales (p. 685), formerly called cycads, 

 abounded, and from them the true cycads sprang. The Triassic 

 floras of Europe and America, so far as known, were much alike. 

 Both had a scrawny pauperitic aspect that reflected the hostile con- 

 ditions in which they lived. In the far east and in the southern 

 hemisphere, the genus Glossopteris and its allies constituted a marked 

 feature of a flora whose general aspect was much like that of the 

 preceding Permian flora in the same regions. 



In the closing stages of the period an ampler flora seems to record 

 some amelioration of the inhospitable conditions. The larger part 



