Re: Vampire-osaurs?

[Christopher Taylor <ck.taylor@auckland.ac.nz>]

On 3/7/04 6:06 pm, "Michael Habib" <mbh3q@virginia.edu> wrote:

> More generally speaking, though, I would take some care in suggesting that
> dinosaurs were likely to be poisonous or venomous because extant reptiles
> are.  The only venomous extant reptiles fall within the helodermids (Gila
> Monster and beaded lizard) and snakes, which are rather related, so venom
> use is only common in one clade of lepidosaurs.  I believe (can someone
> confirm?) that there are some poisonous birds, but only a few out of the
> some 10,000 species.  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.
> 

    The only known poisonous bird, AFAIK, is the pitohui, a small passerine
from New Guinea, and a type of whistler (Pachycephalidae). Probably quite
derived within birds, so not informative about stem forms.
    The venom (which I don't think is very strong) is secreted in the
saliva, and enters a wound passively when the bird bites. Seeing as I would
suspect the pitohui to be insectivorous (I don't actually know, but all
other whistlers are), I suspect the toxin is probably used defensively - a
nasty nip to a potential predator is even more effective a deterrent when
accompanied by an annoying itchy, nose-swiping numbness.
    Most interestingly, the pitohui's toxicity was only discovered quite
recently - early 1990s, I think. Sometimes, when it comes to places like
Papua New Guinea, we know so little about the animals happily living and
thriving there that they might just as well have been extinct for 60 million
years :-S

    Cheers,

        Christopher Taylor