De evolutie van de olifantachtigen

This article present some information about the distribution and special adaptations of the two present-day elephant species, such as the structure of their spinal columns, their legs and their dentition, with special reference to molar structure and their horizontal replacement. The origin and evolution of the proboscidians since the Eocene is dealt within detail. During the course of evolution there was a gradual increase in body size, in the size of their molars and in the number of transverse ridges in each molar. This culminated in the true elephants of the Pleistocene to which the woolly mammoth also belonged. A special characteristic of the true elephants is that, apart from the increase in the number of molar ridges, the height of the molars is also greatly increased. Having undergone the first part of their evolution in Africa, since the Miocene the proboscidians spread over almost the entire world to reach their maximum distribution in the Pleistocene. Towards the end of this period, however, most species became extinct and the two present-day elephants in fact constitute there mains of a once very succesful animal group.