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Venom in Sinornithosaurus



Okay, I understand that folks are skeptical about this proposal (venomous 
sinornithosaurs), and I do certainly understand the skepticism. But having now 
read the paper, I feel that this skepticism is misplaced.

Regarding the "teeth just slipped out of their sockets" thing, this is likely 
incorrect. There are several specimens of *Sinornithosaurus* that preserve the 
very same elongation of the teeth, and always maxillary teeth 8 - 11. Some 
rather incredible coincidence.

Note that although many non-venomous extant taxa do indeed possess grooved 
teeth, the presence of grooved *rear* teeth has never, ever been documented in 
any non-venomous animal, as Brian Fry has noted. It is especially suspicious 
that only the longest, sharpest, and most "fang-like" teeth have grooves.

Also remember that the proposed "venom-gland depression" is actually *below* 
the antorbital fossa and is separated from it by a thin bar of bone, and so it 
is not the same structure nor is it a part of that structure.

Many people are saying that the fact that venom glands are unknown in 
archosaurs weighs against the hypothesis of venomous dinosaurs. I feel that 
this is nonsensical because we have only two groups of extant archosaurs - 
crocs and birds. Two extant clades is *way* too small a sample size to allow 
one to say if venom is extraordinary for an archosaur or not. These two extant 
clades are also not at all diverse in oral anatomy - *all* crocs have the exact 
same naked, lipless teeth, and *all* birds have beaks, without exception - and 
I rather doubt that a venomous bite is even possible for a beaked or lipless 
animal.

What I think we need to be doing is celebrating a truly amazing new discovery, 
or at the very least contemplating what sort of implications this would have if 
true. We should not be so closed-minded, leaning back in our chairs trying to 
figure out how to "reinterpret" or dismiss the evidence. Something we should 
definitely avoid is an ad hominem attack on the paper - i.e. casting immediate 
doubt on it simply because a BANDit (Martin) happens to be involved. I honestly 
believe that the authors have done a fantastic job of supporting their case*, 
but even if they didn't, the burdon of proof does not automatically lie with 
the "new" or "radical" theory/hypothesis anyway; rather, it lies with *us* to 
demonstrate that the "traditional" or "widely accepted" view is well-supported 
enough as to not be challenged. Often, nearly universally accepted ideas (the 
ectothermic and featherless dinosaurs of the majority of the last century, for 
example) in reality have little to no factual basis, or are based merely on an 
absence of contrary evidence. The burden did not lie on those such as Ostrom 
and Bakker who were advocating endothermic (or even feathered) coelurosaurs; 
the burden was on those who maintained ectothermic and scaly coelurosaurs to 
demonstrate that the classical view was was the correct one, or that it was at 
least based on *something*. They failed to do this, and the enormous mountain 
of data that has accumulated since has demonstrated beyond any reasonable doubt 
that Ostrom and Bakker were correct. Perhaps this conclusion could have been 
reached even sooner, and thus the science could have progressed even farther 
than it has now, had folks not been so dead-set against such notions for the 
first few years fallowing their initial proposal and used up so much time 
trying to prove these "crazy new ideas" wrong, a task at which they did not 
succeed in any case.

Just my totally irreverent, idiosyncratic one cent's worth.

*especially considering that all they had to work with was _the skull alone_, 
and venom delivery systems in extant animals often _don't even have any sort of 
osteological correlates_.

~ Michael                                         
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