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Re: Venom in Sinornithosaurus



--- On Wed, 12/23/09, Michael Erickson <tehdinomahn@live.com> wrote:
> 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.
> 

OK, I'll believe these grooves are real.

> 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.
> 

Of course, long knives have grooves, but they aren't for venom delivery (or the 
other misconception, that they work the other way around, to let blood come out 
while the knife is still in).
This may simply be a weight saving feature, as with human designed knives 
(although often the grooves aren't to impart I-beam like strength/weight 
ratios, but rather they do it just for aesthetic appeal)
The entire skull does look rather lightly built.
The longest teeth would need the most strength to keep from breaking, so a 
groove on the longest teeth makes sense if you only wanted to reduce weight.

> 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.
> 

OK, but its still just a depression, that says little about function.

> 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. 

I agree, if the platypus/monotremes had gone extinct, we'd have no examples of 
venomous mammals (as far as I know)

And if in a million years there were no snakes, and if a few lizard species 
went extinct, we'd be saying reptiles shouldn't be venomous by that logic as 
well.

> 
> 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.
Re-interpreting evidence is always fine with me - I'm glad T-rex's aren't 
depicted in the tripod stance anymore, are you?


> 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. 
Well... having not read the paper, and just seeing news articles, one does tend 
to think: "Oh that guy that makes baseless claims is making another claim..... 
time to ignore it like the rest of his claims"
I'd make an analogy to certain religions here, if it wouldn't come close to 
violating the mailing list policies.....


> 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. 
Saying the current view is right, is not the same as saying the "new" view is 
wrong, and likewise, saying the "new" view is wrong, does not mean the current 
view is right.

If I were to claim all theropods had retractable neck frills as depicted in 
Jurassic park on Dilophosaurus, would the burden of proof lie on the rest of 
you to say it is wrong?
To use a more well known example,
If I were to assert there is a teacup orbiting the sun, somewhere in between 
Mars and Jupiter, and say the burden of proof lies on you to prove me wrong, 
would you conclude you cannot prove one isn't there, therefore you must accept 
my assertion?
http://en.wikipedia.org/wiki/Russell's_teapot

We don't need to prove no Theropods had venom, we only need to show the claim 
that *this particular theropod* had venom is not adequately supported.

That still leaves it open for other dinosaurs to be found with Venom delivery 
systems.