Re: pterosaurian pterrors

[jrhutch@socrates.berkeley.edu (John R. Hutchinson)]

>I will admit that "gestalt" conceptions of biomechanical plausibility are not
>the most rigorous kind of science, but they are at least a start.  I can
>tell, for instance, that _Anhanguera_ was not a full-time swimmer or
>borrower, that it did not walk on its hands alone, and that it did not run
>along on two feet with its back held horizontally like a theropod or
>(perhaps) a "rhamphorhynchoid".  Will you dismiss these conclusions, based as
>they are on a general overview of the animal's skeletal structure?

I won't dismiss them, but I won't agree with them either.  I've never
handled a pterosaur specimen, moved its bones around, looked at its joint
surfaces, muscle scars, etc., so I must confess that I don't know what the
answer would be, especially to the question of body posture w.r.t. the
horizontal, or whether they could run bipedally. I don't know of any
osteological features that would prevent them from running bipedally, but
that's not a test of the hypothesis that they did do so.

I don't think pterosaurs did the hootchie-coo or the macarena (on a regular
basis, at least), but that's not an interesting question.  I don't know if
they borrowed often, perhaps there was a bank pteller that they frequented,
but the fossil record is silent on that issue.  Gosh, I'm sorry about that
one.  Getting late.  Ptoo late.  I'm getting ptired. :-)

Anyway, we don't know much about how living animals work; that's a given.
I think (and know that Kevin would agree with me) that extinct animals,
especially those with no particularly close, and hence morphologically and
functionally similar, living relatives (e.g. pterosaurs, _Ptriceratops_,
etc.), are even more difficult to reconstruct without meticulous hands-on
functional morphological study of specimens, biomechanical analysis, etc.
And even then... who knows?  Lots of vagaries to deal with.  Remember that
animals aren't just made of bones; they have muscles, nerves, cartilage,
tendons, their own body mass, etc. that all interact to produce the
phenomenon of locomotion.  Even a study of functional osteology leaves lots
unanswered; the more unknowns, the shakier our conclusions are.

I don't work on pterosaurs; theropod functional morphology is one of my
interests, but theropods sure ain't pterosaurs despite some similarities.
So I guess my conclusion is that I'd rather not have a conclusion right
now.  I don't know the specimens, I haven't spent years learning the
literature.  My basic point that I sort of made in my previous post is that
it just bugs the heck out of me when scientists make sweeping statements
about functional morphology in vertebrate paleontology without testing
their hypotheses in a biomechanical / functional framework (I won't point
any fingers, but suffice it to say that I doubt I'm setting up a straw man
here).  A biomechanist would practically get tarred and feathered for
making similar suppositions to his/her colleagues (at least that's what my
biomechanics friends tell me).  I don't see any compelling reason that vert
paleo, being a science, and so subject to the same basic procedural
expectations, shouldn't expect the same of its workers' endeavors in
functional morphology.  It might even earn VPers some kudos from the more
neontology-oriented scientists.  That's just my cynical grad student
opinion, love it or leave it.  And this isn't directed at you, Nick, it's
just a soapbox B.S. session for any and all to delete from their mailbox at
their leisure.  And it's almost over.

Frankly, the locomotion of pterosaurs scares the crap out of me; I find
extinct theropods challenging enough even with some vaguely useful
functional analogs.  So (please don't take this as patronizing -- it's not
meant to be so) I'd prefer to leave the conclusions to the experts who know
the specimens and have spent their lives studying them; let 'em slug it
out.  I'm plenty amazed that these things ever lived.  Whatever they were
like, they must have been quite a sight.  Weird bone histology, too; crazy
wacky stuff.  OK, I'm heading off on way too many ptangents here.  Best to
stop while my Mac still has memory left.  Please excuse the excessive use
of ptiresome puns (and parenthetical phrases).  Bye!

                        John R. Hutchinson
                 Department of Integrative Biology
                  3060 Valley Life Sciences Bldg.
                University of California - Berkeley
                     Berkeley, CA 94720 - 3140
                      Phone:  (510) 643-2109
                      Fax:    (510) 642-1822
         http://ucmp1.berkeley.edu/people/jrh/homepage.html