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Re: pterosaur femora sprawl



Tim Williams wrote:

As a postscript, I'll only mention that if the origin of avian flight had an arboreal component, then such pre-avian maniraptorans would probably have climbed trees in a quadrupedal fashion, and may have employed all four limbs in gliding (microraptor-style).<

I think Dial demonstrated rather convincingly several years ago how a feathered pre-avian maniraptoran with an incipient "flight stroke" capability (selected for whatever reason) could have exploited an arboreal environment. Once in the trees, such an animal would have needed to return to the ground somehow, and using whatever aerodynamic function existed in their "proto-wings" for that purpose could have been advantageous for a number of reasons. If there was an arboreal stage in the origin of avian flight, which is an open question, I don't see a compelling argument for the necessity of either a quadrupedal climbing or a four-limb gliding phase.


PTJN