CAN CLIMATE BE INFERRED FROM FOSSILS? 453 



armadillos are represented by extinct gigantic Glyptodons, in which 

 the armour is free from joints, and the living Auchenia is represented 

 by the larger Macrauclienia. The monkey, Protopithecus, which 

 occurs with them, is of the American platyrhine group. 1 



Similarly, in Australia the Marsupials reach their maximum ; and 

 here also gigantic forms occur fossil, and represent most of the groups. 

 Thylacoleo is considered to represent a marsupial carnivore ; Dipro- 

 todon is termed a marsupial pachyderm. Wombats occur as large as 

 tapirs, and there were gigantic kangaroos and large phalangers. It is 

 remarkable that the living Australian lizard Moloch appears to be 

 represented in a fossil state by a gigantic prototype, Megalania. In 

 New Zealand there are found in a barely fossil condition the remains 

 of multitudinous gigantic birds, the most familiar of which is the 

 Dinornis, and these may be regarded as represented at the present day 

 by the surviving ratitse of the Australian province. All giant types 

 appear to have had a short duration in time. 



Climatal Conditions of Ancient Seas. Any attempt to estimate 

 climatal conditions in past ages of the earth's history must rest upon 

 physical evidence. Ice-scratched stones, glaciated rocks, and boulder 

 clay may prove conditions of great cold, but we are acquainted with 

 no physical evidence that would demonstrate heat as a climatic con- 

 dition of the earth. There is nothing in the condition of the skeleton 

 of the musk ox that would indicate the conditions of extreme cold 

 under which the species lives, and no one examining the arctic seals 

 in a fossil state could affirm that they had not lived in tropical waters. 

 It is equally impossible to recognise climatic conditions from structure, 

 collocation of species, or other evidence, for the abundant tertiary flora 

 of Greenland, with its many sub-tropical types, has shown that the 

 distribution of land and water may enable plants as well as animals 

 to flourish in latitudes where their existence would not be suspected 

 from the present distribution of life. Edward Forbes laid down the 

 great doctrine that " every species is controlled by its own peculiar 

 laws, and no acquaintance with one species of a genus, however exten- 

 sive and accurate, warrants us in predicting concerning any other 

 species, even though very striking resemblances may prevail ; for the 

 truths of zoology forbid us to reason concerning the species of a genus 

 in the same manner as we do with the individuals of a species." 

 Many genera are world-wide in distribution, and the habits, food, and 

 climate of one species are quite dissimilar from those of other species. 

 If, then, one recent species cannot indicate the climate under which 

 another species lived, least of all can rare and surviving recent species 

 tell anything of the climatic adaptability of extinct fossil forms. We 

 need scarcely recall attention to the inferences which were drawn 

 when the valley gravels of England first yielded the remains of 

 elephant, rhinoceros, hippopotamus, lion, and associated species, in 

 days before the glacial period was recognised. Such species were 

 almost everywhere affirmed to indicate for Britain a warmer climate 

 in the time when the fossils lived. Subsequently, when the same 

 1 Owen's "Palaeontology," 1862. 



