Venomous snakes have hollow fangs and venom glands. Evolution would
have had to produce both of these innovations together, since either would
be pointless without the other.
Response:
Venom is not pointless without hollow fangs. Gila monsters have venom
glands without hollow fangs. Other venomous snakes have furrowed
fangs. These show plausible intermediate forms to hollow-fanged
venomous snakes:
A nonvenomous snake already has teeth which break the skin of its
victim.
Poisonous saliva becomes advantageous to some snakes because it
can get into the victim and kill it faster.
Furrowed fangs allow the venom to be concentrated in the prey.
The furrows gradually become enclosed, resulting in hollow fangs.
