EVOLUTIONARY HISTORY OF ELEPHANT

Polymorphism within each evolving branch, a wide range of variation, convergent adaptiveness, common heredity, large size, and overlapping of measurements make difficult the systematics of elephants. Only the identification of evolutionary trends may enable us to identify genera and species with sufficient reliability for regular samples. It is uncertain to what extent many of the quantitative differences can be explained as simple variations resulting from local conditions of climate and food supply. Morphological variations are large; thus the affinities and trends in form have to be established carefully. It is probable that the diversification of elephants summarized in Fig. 8 relies on a genetic basis, and it is very difficult to decide at what moment the interbreeding of different forms has terminated.