Check out this article about a theory of dinosaur metabolism that you may not have heard before. It claims that dinosaurs were essentially cold-blooded but that they could rev up their metabolic rates and become warm-blooded when they needed to act fast. Basically dinosaurs could have have their cake (i.e. catch their prey) and eat it too (i.e. consume its energy at a lower metabolic rate over a long period of time). The theory chalks up the extiinction of the dinosaurs to climate change stating that this kind of system, while very efficient, is untenable in a cooler world, and that global cooling killed the dinosaurs.
I really admire the elegance of this theory. It reminds me of Steven Pinker's book Words and Rules, in the way that it synthesizes both sides of a debate into complementary elements.