Re: Vampire-osaurs?

[Michael Habib <mbh3q@virginia.edu>]

>> ... More
>> to the point, however, they would have to be grooved or hollow to
>> inject a
>> toxin, which may or may not be evident from the specimens.
> 
> IF it needed to be injected. I'm pretty sure there are frogs/toads that
> can secret a poisonous substance when the need arises.

Yes, many amphibians can.  However, they have permeable skins, and this
relates to secretion.  No squamate reptiles secrete toxins across the skin
(as far as I can recall), and no extant archosaurs other than the one bird
exception noted on the list (thanks for that guys) do so.

>> Thus, extant archosaurs are not prone to be
>> poison
>> users, and none are venomous.  Overall, reptiles get a reputation as
>> toxin
>> users only because snakes are prone to evolving venom use.  Their
>> unique
>> ecology and physiology plays a major role in this.
> 
> Also, komodo dragons are technically poisonous.  And I believe that sea
> snakes have some of the most toxic venom among snakes. They'd rather
> not go chasing their prey all through the water until the venom takes
> full effect, go following it's scent through the water and/or give
> another predator a free meal. Mosa/Plio/Plesio, anybody? hehehe . . .
> 

Komodo dragons are _technically_ not poisonous.  They have highly infectious
wounds, and the Staph infections resulting produce their own toxins.  No
extant Varanus species injects venom.

True, sea snakes have neuroinhibitors that act rapidly, as do cone snails
and several fish.  So, marine piscavores may have a greater chance of
deriving venom use.  Might be worth looking into to see if any extinct
marine taxa have left signs of venom use (anyone out there have a ref or
two?).  From an extant bracketing point of view, which is granted somewhat
circumstantial, Mosasaurs would be the best candidate.

Cheers,
--Mike Habib