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Re: Bird reduce their "heating bills" in cold climates
Jura <firstname.lastname@example.org> wrote:
> Hardly anything about the skeleton of green iguanas,
> screams arboreal either.
This is true. And, as commonly noted, even goats can climb trees.
However... if one were to hypothesize that a particular fossil taxon was
habitually arboreal, then this hypothesis will stand or fall based on its
arboreal-related characters. So far, no ornithopod (including _Leallynasaura_)
shows any adaptations for climbing or perching.
This is not to suggest that ornithopods (especially the smaller ones) *never*
climbed trees. But, if climbing or perching was indeed an integral part of the
behavior of an ornithopod (as once suggested for _Hypsilophodon_) we would
expect to see limb proportions or discrete characters associated with
arboreality (including scaling trunks or grasping branches). We don't - not in
_Hypsilophodon_, or any other known ornithopod (or ornithischian in general).
This issue comes up in the origin-of-avian-flight debate. Those who argue for
an exclusively "trees-down" origin for avian flight argue that _Archaeopteryx_
was highly adapted for an arboreal lifestyle. However, the anatomical evidence
simply doesn't support this interpretation. _Archaeopteryx_'s climbing and
perching abilities were rudimentary, at best.