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Fwd: Venom in Sinornithosaurus



>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.

Not that it cannot be, it can, but it requires more asumptions (an
evolutionary step indicating acquisition of the venom) that the other
hypothesis does not. That`s the deal with the use of parsimony
phylogenetic, you try to rely on the lesser number of suppositions (in
the case, evolutionary transformations).

Indeed, a dinosaur without grooves and without bony recesses for
venomous glands may also be venomous. We cannot deny it either. But,
this hypothesis is still less parsimonious. I do not know if the
"burden of poof" has to fall in anyone or anyone's assertion (whether
venomous or not venomous) if we have some other optimality criterion
to choose among alternatives...