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Re: Venom in Sinornithosaurus



Excellent point; there is indeed the digestive angle. My followup question on that would be, however: what is it about rear-fanged morphology (or other aspects of the physiology of snakes carrying rear- fanged apparatus) that makes anticoagulation breakdown especially helpful? The widely cytolytic venoms used by many viperids (and quite a few elapids, actually, despite what you often hear) seems to do some serious pre-digestion - the flesh literally starts to fall off of a prey animal injected with such toxins. On other hand, tearing up the blood vessels alone has less of an obvious digestive function. But just because it's less obvious doesn't mean it's wrong - it just raises more questions, is all.

Cheers,

--Mike Habib


Michael Habib
Assistant Professor of Biology
Chatham University
Woodland Road, Pittsburgh PA  15232
Buhl Hall, Room 226A
mhabib@chatham.edu
(443) 280-0181



On Dec 25, 2009, at 1:46 PM, don ohmes wrote:

Well, there is the digestive angle...

--- On Fri, 12/25/09, Mike Habib <habib@jhmi.edu> wrote:

Rear-fanged colubrids are actually quite widespread, both
phylogenetically and geographically.  Only a handful
have venom that is medically significant to humans, but the
few that do really pack a wallop (twig snake, boomslang, a
few others).  Interestingly, despite the convergent
nature of opisthoglyphy in the various venomous colubrid
groups, many (most?) of them seem to share a tendency to
utilize blood vessel wall damage and anticoagulant effects
as a primary attack form.  Very few, if any, are
substantially neurotoxic.  Human fatalities from
boomslang bites, for example, occur as a result of massive
internal bleeding.  Even those species that have little
effect on humans and are not considered "medically
significant" seem to produce somewhat accelerated bleeding
from the bit wound.  To the best of my knowledge, no
one has determined a functional, phylogenetic, or
developmental underpinning to this trend (but someone else
here may know something I don't).

Cheers,

--Mike Habib


Michael Habib
Assistant Professor of Biology
Chatham University
Woodland Road, Pittsburgh PA  15232
Buhl Hall, Room 226A
mhabib@chatha

(443) 280-0181