Tuesday, March 13, 2007

Profound Comment on the KT Extinction

Darren Naish made it in reply to a few of readers' comments:

One more thing on Cretaceous sebecosuchians: the existence of all of these moderately big terrestrial reptiles means we have to revise that old sound-bite about 'no land animals above [insert size] survived the end-Cretaceous event'. We don't have a complete record of sebecosuchians across the K-Pg boudary of course, but the Cretaceous, Palaeocene and Eocene forms that we have indicate that the forms that survived across the boundary were of the same size: viz, pretty big for a terrestrial non-dinosaur, 2-3 m long. Mostly ignored to my knowledge, this fact might mean something important for the metabolic status of dinosaurs, as some commenters here have already noted.

Think about that for a minute. That's damned important. IF the sebecosuchians were ectotherms, this makes complete sense. If there were prolonged periods were food was not available, then being cold blooded is immensely helpful. It also says that the dinos were not cold blooded and the terrestrial forms (ie not the birds) were not able to move around enough to get enough food. One has to wonder why the mammals survived. Could they simply hibernate?

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