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Re: Did pterosaurs feed by skimming?

All good points. Some thoughts inserted below.

"I see two possible problems with this otherwise very cool idea.  The
first is that the rest of the Pteranodon hind limb does not seem to show
any signal of aqueous propulsion, and morphologic signals related to
fluid medium show up very clearly in birds (though, admittedly, most of
the available limbs are flattened beyond all recognition, making this
conclusion tentative).  Pterosaurs don't have to follow the same
patterns as birds, but enough of the mechanics would be consistent that
I find it doubtful that pterosaurs could be swimming and not have to
deal with loads at least somewhat similar to those experienced by
swimming birds."

True - they're certainly lacking devleoped processes on the tarsi and
tibia that we might expect from swimming birds. What strikes me is that
pterosaur hindlimbs appear very simple in their structure - really
tubular. As you say though, this might be because lots of them are
squashed flat, crushing all their topography into one plane, but the
nice Santana Formation specimens seem to verify it. I'm not sure what
this means for swimming: maybe pterosaurs weren't very good at it at
all. That said, trace fossil evidence suggests that at least some
pterosaurs swam, so I guess they managed it without developed hypotarsus
and cnemial crest. Thinking about it, those trace fossils tell us a bit
about how pterosaurs might have swam, with their hindlimbs paddling in a
parasagittal fashion. I'm not sure their forelimbs would be much use in
swimming, mind.

" Gulls can also dip feed, I think, and lack much of a hook."

As far as I'm aware (and I'm no expert), gulls are stationary feeders,
either standing or alighting on the water surface. I might go and check
that out to confirm it, though. 

"Of course, Pteranodon must have been doing *something* to eat"

Nah - they had symbiotic photosynthetic algae in the wings and
headcrest. Solar gliders, folks, solar gliders...


Mark Witton
Palaeobiology Research Group
School of Earth and Environmental Sciences
University of Portsmouth
Burnaby Building
Burnaby Road
Tel: (44)2392 842418
E-mail: Mark.Witton@port.ac.uk