PALEOBOTANICAL EVIDENCE 517 



on a great scale in many parts of the world, but notably along the Pacific 

 from central California to Alaska, and along the eastern Atlantic from 

 Virginia to Kova Scotia. Schnchert says : 



"Just how important this movement was and what effect it had upon the 

 climate is not yet clear, but there is important organic evidence leading to the 

 belief that the temperature was considerably reduced during latest Triassic 

 and earliest Jurassic time." 



He then points ont that of the 1,000 or more species of Triassic am- 

 monites not one is known to have survived into the Jurassic. The in- 

 sects of the Liassic, of which group over 400 species are known, appear 

 to have been quite uniformly dwarfed in size, which is interpreted by 

 Handlirsch as indicating a cooling of the climate, perhaps to that of the 

 present temperature of northern Europe between latitudes 46° and 55°. 



From these data Schuchert concludes thus : ^^We therefore are seem- 

 ingly warranted in concluding that the cooling of the climate in late 

 Triassic and early Jurassic time was not local in character, but was 

 rather of a general nature." 



According to Schuchert the evidence offered by the marine inverte- 

 brates is in substantial agreement with that of the plants. The late 

 Paleozoic forms were almost wholly replaced by a new assemblage, and 

 certain forms, especially in Middle and late Triassic time, attained aii 

 extremely wide distribution. Schuchert says : 



"We may therefore conclude that the rigid climate of the Permic had van- 

 ished even before the earliest of Triassic times, and that the climate of the 

 latter period until near its close was again mild and uniform, though semi- 

 arid or even arid the world over." 



James Perrin Smith, after discussing the very wide range of certain 

 limestones with thick coral reefs, interprets •the evidence as indicating 

 a "nearly uniform distribution of warm water over a great part of tlie 

 globe'^ during Triassic time. 



Jurassic floras. — In the lower portion of the Jurassic we find indica- 

 tions of a continuation of conditions which obtained in the upper por- 

 tion of the Triassic. The distinctive Paleozoic elements had finally 

 disappeared, and the Mesozoic life forms were in full swing, expanding 

 in the middle and upper parts of the Jurassic into the abundant and 

 wide-spread flora as we now know it. In fact, the Jurassic flora enjoyed 

 in many respects the most marvelous distribution of any known flora, 

 either living or fossil. It is known to range from Franz Josef Land, 

 82° N., to Hope Bay, Graham Land, 63° S., and from extreme western 



