"Dilophosaurus, " the tape said, "is one of the earliest carnivorous dinosaurs. Scientists
thought their jaw muscles were too weak to kill prey, and imagined they were primarily
scavengers. But now we know they are poisonous."
"Dilophosaurus secretes a hematotoxin from glands in its mouth. Unconsciousness follows within minutes of a bite. The
dinosaur will then finish the victim off at its leisure - making Dilophosaurus a beautiful but deadly
addition to the animals you see here at Jurassic Park."
That's a direct quote from the novel. Venomous and poisonous are basically the same thing. The difference is a poisonous animal doesn't need to bite the victim to use it's venom. It could be spitting or releasing venom from other parts of the body... Fish and frogs can be poisonous through skin coating or with stingers... A venomous animal can only transfer venom through bites. And since the Dilo has glands in its mouth, it can actually utilize both. So yes they are venomous through bites, as the quote in the novel states.