Southern biogeography on the basis of continental drift: a review.

Abstract

Several independent lines of evidence show that continental drift has occurred on a large scale. The southern super-continent Gondwanaland, rifted during the earlier Mesozoic, began to fragment during the Cretaceous. The larger Gondwanic continental areas experienced some aridity during the late Tertiary and Pleistocene, while other smaller land areas continued to enjoy moist isothermal conditions. Different climates have led to the selection of different elements from the same original Gondwanic flora, which largely accounts for the various floristic disjunctions of the southern hemisphere. There has also been some mingling with northern floras; much plant migration probably occurred during the Pleistocene. Many animal taxa show disjunct southern distributions, explicable in terms of continental drift. The early migrations of primitive mammals, in Cretaceous times, were followed by separate processes of evolution and extinction on the separate drifted continents of the Tertiary. Gondwanaland was an important centre of evolution. The mainly southern distribution of primitive angiosperms may indicate a Gondwanic origin for the group.