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IIRC, this was already the standard story of snake evolution. I believe the remaining mystery revolves around which lineage they evolved from. Skinks, monitors

by netcan 5y ago

IIRC, this was already the standard story of snake evolution. I believe the remaining mystery revolves around which lineage they evolved from. Skinks, monitors and I believe Plesiosaurs are proposed as possibilities... At present, there are multiple lineages of non-snake, legless lizards. That basic body plan is relatively abundant, probably was then too. One of these lineages started to diversify into snakes after KT. Large fauna extinctions probably made small prey more abundant, so it's a good time to be a snake. A lot of snakes are mammal specialists, which also succeeded after KT. Snakes may have started to proliferate in response to the post KT abundance small burrowing mammals.

pfdietz 5y ago
There are plenty of weird legless tetrapods back as far as the Carboniferous. It's an ancient niche.
nickik 5y ago
But didn't snakes evolve from something with legs? There are a number of snakes, specially historically with legs and some where the leg bones are still there. Legless lizards and snakes some to convergent evolution. But its of course possible that other legless lizards existed before that.
- netcan 5y ago
  There are modern species of snakes with vestigial legs today, pythons, boas... Leglessness in lizards not very uncommon. It evolves regularly, before and after the snake lineage likely originates. One species of such creatures became the ancestor of snakes. I think (not an expert) that the lineage of that creature is still speculative... with a still-wide range of candidates. Not sure if Plesiosaurs are still a contender, but if it is then it gives Plesiosaurs the same relationship to snakes that birds have to dinosaurs.