Dawkins on Noah's Ark

[Blind groper]

The oceans going anoxic would not kill off the marine reptiles, since they breath air anyway.

My view is that the asteroid strike would have killed off most of the photosynthetic plant life due to a 'nuclear winter' effect, blocking sunlight. The large plant eating dinosaurs would die, and their predators a little later. Insects would survive, among the plant detritus, and their predators, like birds and mammals. Seeds would remain, and the clearing of clouds would permit plant growth again. But by that time, the big dinosaurs would be extinct.

Marine plant life would also mostly die off, leaving an extinction through the food chain, up to the predatory marine reptiles. Crocodiles can survive for many months without food. Maybe that was long enough to carry them to when the ocean ecosystems began to revive. Marine turtles also survived, but they are more versatile in terms of food and can eat stuff like jellyfish.