QUOTE(Rare and Unusual Human Creature @ Apr 21 2006, 09:03 PM) [snapback]1158364[/snapback]
They don't know for a fact it didn't spit venom, do they?
Nice pics in this thread, by the way.
Yes and no. It wasn't venomous in the sense that it injected venom with a bite; that would require hollow fangs, or at least a groove to direct the venom. Nothing even remotely resembling that has been found in any dinosaur, and it is believed that venom didn't evolve until later.
However, it is possible that it could spit venom. That would require only a venom gland; glands don't fossilize, so we can never know for sure that it didn't have one.
That said, the odds are very much against it. As I said, dilophosaurus was an apex predator; it was the biggest, baddest, strongest dinosaur around. It had no use for venom because it could out-muscle its prey. Modern animals in a similar position as dilophosaurus - lions, eagles, crocodiles, etc - are, without exception, non-venomous. The only even remotely venomous apex predator is the komodo dragon, which is not venomous but its saliva contains lethal bacteria. Even then, the dragon kills by biting, not spitting, as the bacteria requires an open wound to infect the bloodstream. Furthermore, the closest living reletives of dinosaurs are birds. No birds are venomous, which suggests that the line of dinosaurus that gave rise to birds - and dilophosaurus is a close reletive of that line - probably also lacked venom.
Thus, while we can't say with absolute certainty that they were non-venomous, we are about 95% sure.
-Pilgrim