Palaeontology both borrows from and sheds light upon geology and other branches of the physical history of the earth, each of which, such as palaeogeography or palaeometeorology, is the more fascinating because of the large element of the unknown, the need for constructive imagination, the appeal to other branches of biological and physical investigation for supplementary evidence, and the necessity of constant comparison with the present aspects of nature.
The beginnings of palaeogeography followed those of palaeometeorology.
South American palaeogeography has been traced by von Ihring into a northern land mass, " Archelenis," and a southern mass, " Archiplata," the latter at times united with an antarctic continent.
Closely connected with palaeogeography is zoogeography, the animal distribution of past periods.
No other system of the United States brings out more clearly the value of palaeontology to palaeogeography.