No, cladograms deal with living species.
Oxygen.
Oxygen was fatal when organisms started using photosynthesis, this event was known as the Great Oxidation Event.
They eat other snakes, including venomous snakes. They have developed a hunting technique to avoid being bitten by clamping down on the jaws of the venomous prey, but even if bitten, they are immune to the venom. They also eat amphibians, turtle eggs, lizards, and small mammals, which they kill by constriction.
I think its pulmonary circulation too.
