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Re: SV: Floating pterosaurs

That would presume that pterosaurs used an avian-style launch, which is doubtful. Granted, I'm a little biased on this issue, having published a paper on it, but Jim and I also have a rather substantial amount of data to back it up. So, while I agree that a larger pterosaur would have trouble launching from the water in the manner of a large living seabird, I also suggest that they did not have to, using alternative modes of launch, instead.
Incidentally, we need to keep in mind that there have been giant fossil seabirds, as well, some of which seem to have been adapted to surface swimming (i.e. pseudodontorns). The largest pseudodontorns likely mass 50 kg or more, and yet probably did manage water launches in the manner of living seabirds. So while there is a limit on the avian style launch, and the relevant size limit is well below the size reached by things like large azhdarchid pterosaurs, the mass limits are also well above what we see represented in modern birds. 

Cheers,

--Mike


Michael Habib, M.S.
PhD. Candidate
Center for Functional Anatomy and Evolution
Johns Hopkins School of Medicine
1830 E. Monument Street
Baltimore, MD 21205
(443) 280-0181
habib@jhmi.edu



On Jul 6, 2009, at 2:52 PM, Tommy Tyrberg wrote:


I must say that based on my experience of large seabirds I strongly
doubt that it was mechanically feasible for the larger pterosaurs to
take off from water in a calm, but that it was probably possible in a
moderate headwind.
Note that it is not absolutely necessary for seabirds to be able to land 
on water. Frigatebirds can't, but still spend most of their lives over
the sea. However they don't occur in Mid-ocean (unless there are
islands, like Ascension). However I suppose it is not very likely that
any fossil pterosaurs are known from abyssal sediments.

Tommy Tyrberg

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Ämne: Re: Floating pterosaurs

Preliminary calculations indicate that pterosaurs could have taken off
from
fresh water without significant difficulty, at least up the midrange
sizes
(5 to 7 meters span).  Larger ones may have been able to do so as well
-- haven't looked at them yet. Taking off from salt water would be easier. 
JimC

----- Original Message -----
From: "Dann Pigdon" <dannj@alphalink.com.au>
To: <dinosaur@usc.edu>
Sent: Sunday, July 05, 2009 6:22 PM
Subject: Re: Floating pterosaurs



might also have been possible for pterosaurs to have taken off wet,

since

they used skin membranes instead of feathers. Then again, modern bats
don't do well when they
fall into water.