Tetrapod evolution and climate change
It is tempting to think of climate change as a recent phenomenon. However, in some ways the only predictable thing about climate is the certainty of change. There have been at least four major glaciations during the Phanerozoic (icehouse periods) and in between there is usually little or no evidence for permanent ice existing at the poles (these are called greenhouse periods). In addition to climatic oscillations, there have been unique changes caused by tectonics or by biological evolution. These events have almost certainly influenced the evolution of major tetrapods, and also their relative success.
The evolution of amphibians from fish took place in the wet, warm tropics of a large continent. Reptiles evolved from amphibians in these same forests, which began to become more arid during later Carboniferous times. This climatic drying trend continued into the early Permian, when conditions also became much warmer in continental interiors due to the formation of the supercontinent of Pangea. Huge deserts on this continent would have been impossible for amphibians to live in, but were accessible to reptiles, especially those that needed the least water.
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