GEOL 104 Dinosaurs: A Natural History

Fall Semester 2006
Dinosaur Physiology roundup

Some ways in which dinosaurs are distinctly different from modern mammalian communities:

So, what is the answer to dinosaur physiology & ecology? We still don't know.

Current status, and some scenarios:
We know that:

Scenario I: Bakker or "Hot-Blooded Dinosaurs" model
Dinosauria (and probably Ornithodira) were endothermic tachymetabolic homeotherms; therapsids and pseudosuchians had intermediate rates (crocs would thus be a reversal).

Scenario II: Ruben or "Good Reptile" model
No dinosaur was warm-blooded, but at least some had means of rapidly oxygenating their blood to be "turbo-charged" and thus function temporarily as highly active animals. True endothermic tachymetabolic homeothermy doesn't appear until after Archaeopteryx.

Scenario III: an intermediate model ("Damn Good Reptile" model)
All dinosaurs had some degree of endothermic tachymetabolic homeothermy while young; small dinosaurs retained this into adulthood. Large dinosaurs experienced a slow down in metabolic rate, but still higher than any cold-blooded animal (~ 2/3 the rate of mammals of same size). Efficient oxygenation of blood and gigantothermy allowed these dinosaurs to be as active as mammals without the same energy costs.

Still much work to be done.

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Last modified: 14 July 2006