Savanna Hypothesis, Myth, and Dilemma!

The general scenario for the late tertiary involves climatic change from the typical tropical (warm and moist) Oligocene forests to the subtropical early to middle Miocene forests and eventually to the more arid and cooler temperate Plio-Pleistocene environments. These climatic changes were critical for the evolution of all mammalian species, with stronger influence, of course, on herbivores. It is recognized for a long time that the general pattern along the tertiary is that forests were reduced and savannas and grasslands developed and expanded (Culver and Rawson 2000; Jacobs et al. 1999; Stromberg et al. 2007). It is a basic rule of paleoecology and paleoclimatology that evaluation of past ecology and climates is accomplished on the basis of floral and faunal evidences (and other eological/geochemical proxies), with fossil forms compared directly with modern ones considered most similar in morphological respects. It is assumed that the fossil plants or animals being studied lived under ecological and climatological conditions similar to those under which their closest modern counterparts live today. A further step involves the crucial question when from fossil forms we broaden our target trying to study continental fossil ecosystems. The question is, “What was the paleoecology of this studied biome?” Especially during the Neogene, such a question is essential for understanding the morphological changes observed in the continental mammal species.