24 THE PALEONTOLOGIC RECORD 



PALEONTOLOGIC EVIDENCES OF CLIMATE 



BY T. W. STANTON 



U. S. GEOLOGICAL SURVEY 



nnO every one climate is an interesting theme. The climates of the 

 -L past, especially when they can be shown to differ in character 

 or distribution from those of the present, attract the attention of the 

 general public, and they are of importance to the special student of 

 geologic history whether his researches deal with the purely physical 

 aspects of the subject or include some branch of paleontologic study. 



The evidence as to former climates comes from many sources. The 

 records of deposition and denudation in themselves sometimes give 

 more or less definite indications concerning variations in temperature 

 or moisture or both; the land floras when compared with those now 

 living by their general characters and by the details of their structure, 

 show more or less clearly the climatic conditions under which they 

 lived ; the land animals, especially the higher vertebrates, afford a good 

 basis for inferring their habits and hence indirectly their environment, 

 including climate; marine invertebrates give trustworthy evidence of 

 differences in temperature of oceanic littoral waters at least in the later 

 periods. It is obvious, however that the data furnished by any one of 

 these lines of evidence will make only unconnected fragments of the 

 history of past climates and that the evidence on the climate of any 

 particular epoch, if derived from a single source, is seldom so complete 

 or so convincing that corroborative testimony from other sources is not 

 desirable. The subject is one in which general cooperation is essential. 



It should be stated at the outset that the most abundant and most 

 definite evidence comes from paleobotany, and will be outlined in Mr. 

 White's paper. The discussion of the data derived from fossil verte- 

 brates must also be left for some one who is qualified to present it, and 

 the whole Paleozoic era may be passed over with the statement that so 

 far as indications from the animal life are concerned the climate of 

 the whole earth was mild and equable. The proof of local exceptions 

 to this statement comes from other sources. 



All inferences from paleontologic evidence as to former climatic 

 conditions rest in the final analysis on a comparison with the present 

 distribution of animals and plants with reference to climate. Such 

 comparisons may be general or specific, direct or indirect, and the con- 



