Eyes

[Stefan-A]

I am not so sure about that. I was under the impression that colubrids and vipers are the "newer" snakes and that the intricate varieties of venom (whether lethal or not) are the "cutting edge" of snake evolution.

Fossil record indicate boids to be among the oldest snakes (with their vestigial hips and spurs). I would think (don't quote me on that) death by constriction may go way back!

Steve

The evolution of the snake from lizards, which also have the gene as you mentioned (meaning that venom actually predates snakes) to a more subterranean lifestyle would suggest that constriction probably wasn't the first method and it certainly wouldn't be a practical one under those conditions. Venom on the other hand would be. Constriction probably wouldn't have been a solution until the snakes started to return to the surface.

But you are definitely right about boids coming early and viperids etc. being a more recent "invention".