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Re: "No Bolides!"
Minor stuff about climate change:
The argument seems to be that major changes in the temperature
of the environment could directly impact the dinosaurs, and I don't think
that's justifiable if we accept dinosaurs as warm-bloods. (which I'd say
that critters like Cryolophosaurus and the Australia big-eyed
hypsilophodonts argue pretty strongly for). Warm-bloods don't really have
that much of a problem coping with temperature changes. What warm-bloods
have done is change from being tied down by temperature to being tied
down by food as a limiting factor (well, that's one very general way to
look at it). Dinosaurs won't die when it gets cold, they'll die, however,
if food runs out. If the climate changes cause big changes in food
availability, that can do it, but it probably wouldn't be enough to wipe
out the dinos directly.
Which is also why polar dinosaurs argue so strongly for
warm-bloodedness. Big ectotherms like Megalania, Geochelone, pythons,
etc. are tropical and subtropical animals; while coldbloods are mostly
absent from the poles. It's endotherms like penguins, arctic foxes, polar
bears, musk oxen etc. that can survive where it's cold. And while the
Cretaceous did not get as cold as our modern Ice-Age times, it certainly
seems to have been too cold for ectotherms at the poles. As long as it
can get the food to keep its metabolism going and it has sufficient
insulation, a jay or fox can survive sixty below in the Alaskan Interior.