Re: pterosaur femora sprawl

[ptnorton <ptnorton@suscom-maine.net>]

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