Re: Vampire-osaurs?

[Michael Habib <mbh3q@virginia.edu>]

> I've long been wondering about the 'poisonous tendencies' of dinosaurs,
> especially given that living reptiles tend to be the most common to
> have some sort of poison, next to bugs and fishes. Has anybody else
> concluded that the quills toward the posterior of the otherwise
> defenseless psittacosaurus may have been poison-filled? Well unless
> they just wanted to be more noticeable to predators . .?


Well, I am not fully up to date on the morphology of the psittacosaur
quills, but it seems unlikely that they would contain venom tubes.  As far
as I know, they were very long and likely flexible, which does not make a
very good venom injection mechanism (would tend to bend and not stab).  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.

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.

Just a few thoughts for what they're worth

Cheers,
--Mike