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Re: Hone and Benton 2007 (their second paper)




----- Original Message ----- From: "Michael Habib" <mhabib5@jhmi.edu>
To: "DML" <dinosaur@usc.edu>
Sent: Wednesday, May 23, 2007 9:44 PM
Subject: Re: Hone and Benton 2007 (their second paper)



In addition, the build and mechanics of most pterosaurs are not set up such that they would gain a great deal by bipedal locomotion (as best I can tell, in any case).

I agree, but also note that they would need the ability to take a couple of bipedal steps or hops when landing (sort of a 'stutter-step', an asymmetric hop just before the first manus touches down). On landing, there would be no need for a digitigrade pes, nor for the ability to run bipedally.


I doubt that bipedal running would be faster for them,

I would expect bipedal running to be slower for them than quadrupedal running, but don't see the need for them to have much of an ability at either. That said, I speculate that they could move rather rapidly with a quadrupedal gait, though I haven't seen any trackways that illustrate them doing so.


and quadrapedal launching would be more powerful (and is supported by several aspects of morphology, especially in larger pterosaurs).

I agree, and hope to have more to say on that at Munich, budget permitting :-)


Just because we cannot see the benefit does not mean it did not exist, but it does make me more skeptical of the concept of bipedal progression in pterosaurs as a common means of transport.

So far, I've not seen any trackways that demonstrate more than a couple of consecutive bipedal steps.


The fact that the interphalangeal lines do not preclude bipedality in pterosaurs is useful to know, but I suspect it is not a result of bipedal running.

Me too. I would expect the pes to be capable of reaching a transient and momentary 'digitigrade' articulation during launch, but to remain in a 'plantigrade' articulation during landing. The former could be mistaken for evidence of bipedality, but I don't personally know of any tracks that demonstrate a launch. I would be willing to bet that there are some out there somewhere..........


JimC