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Re: New refs (short)

DinoBoyGraphics@aol.com wrote:

Monotremes and marsupials show a whole suite of morphological and reproductive variety beyond placentals, so by any morphological standard, they would better approximate the diversity seen within archosauria (or maybe ornithodira, if such a clade exists), which does indeed show a wider range of RMR strategies.

Sorry, but your comparison is still artificial. It's also circular (just read the above paragraph and you'll see why).

And you haven't explained why the Archosauria can (and did) evolve different metabolic strategies, whereas a subset of this group (the Dinosauria) could not. Why couldn't they?

There is evidence that the agile, upright ancestors of crocodylians were endotherms. If endothermic sphenosuchians could give rise to ectothermic crocs, why couldn't there be metabolic changeovers within (say) the ornithopod or theropod lineages? Your argument is "Because placentals all have the same RMR." My reply is "So what?"


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