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Re: Hone and Benton 2007 (their second paper)

This reminds me of another question I had. (Keep in mind that I'm not very knowledgeable about pterosaur aerodynamics, so bear with me...) Certain pterosaurs (e.g., _Dimorphodon_) appear to have grasping adaptations in the feet, including similar phalangeal proportions to arboreal birds (Clark et al., 1998). So it's been suggested that these pterosaurs were capable of climbing. If true, how would a pterosaur launch itself from a tree? Having both grasping manual and pedal claws would allow the pterosaur to grip the tree with all four limbs, but how would it launch itself into the air?

Being in a tree actually makes launching quite easy, since the animal can use a gravity-assisted launch. Essentially, an arboreal pterosaur could simply drop off the tree and then start flapping. It would hit flight speed quite rapidly using gravity-assisted launch, so the animal need not fall very far. Arboreal birds use gravity assisted launches, as do cliff-dwellers like tropicbirds. Arboreal birds do not require gravity assistance, while tropicbirds (and frigatebirds) often do. However, in both cases, the vertical descent prior to reaching cruising speed is quite short. You can see it if you look for it, however. Like arboreal birds, a tree-dwelling pterosaur would not require a gravity assisted launch, but it saves energy if you happen to be at a high point already.

If a pterosaur were launching from a tree (be it a trunk or a branch), it could either use gravity-assistance, or a leaping launch (just as from the ground for a branch launch; there would be a twist after the initial leap involved for trunk launching). More than likely, arboreal pterosaurs would use a combination of both gravity assistance and leaping (which is what arboreal birds tend to do, especially larger ones).

I hope that helps; definitely an excellent question.


--Mike H.