I asked this question here a few years back… but I didn’t get a definitive answer. Given advancements in the field I was hoping there might be some new theories. In college, twently years ago, when I originally asked it all I got was blank stares from my Biology professor.
While watching a pre-recorded Nova special last night about Crocs that live in caves in Madagascar, they once again reminded us that Crocodiles (as well as Turtles I believe) have been around “since the days of the dinosaures”. I think Sharks have been around that long also, but let’s leave them out of the discussion for now. So 65 million years ago something large slammed into the earth that ultimately led to the extinction of all dinosaures (except birds?). So why didn’t whatever it was that caused this mass extinction also kill off the crocs and turtles? What’s the prevailing theory?
Dunno if it’s an actual “theory”, but common sense would seem to indicate that reptiles that are able to go weeks or even months without eating could survive simply by waiting it out. The Wiki article has a good overview.
Well, first off I’d note that Crocs, Turtles, and Sharks are not dinosaurs so that’s probably a part of it.
Also, note that all of the listed groups are semi/entirely aquatic.
And I don’t think it’s so much that the dinosaur killer laid waste to all land animals but rather that it made LARGE land animals non-viable for a period of time. The smaller, more capable of adapting animals came through it. Not all of them, certainly, but enough to keep things moving.
I mentioned this before in relation to another K-T impact thread, but a wide assortment of creatures were driven to extinction at the K-T boundary. On the other hand, some groups came through it virtually unscathed.
Four out of 15 families of latest-Cretaceous turtles went extinct (27% rate), five of 14 families of crocs (36% rate).
Amphibians seem not to have noticed. Lizards and snakes, primitive mammals, and placental mammals lost only one family each.
In general, being small and/or cold blooded seems to have been an advantage in surviving the K-T impact.
Marine reptiles were hit just as hard as dinosaurs. Ammonites went completely extinct. The big winners: fish! Yep, the big winners of the K-T sweepstakes weren’t cunning little mammals, but rather fish. God killed the dinosaurs to make way for trout.
Freshwater groups in particular seem to have fared on average better than many other groups. Turtles, crocs, frogs, salamanders, etc all survived. Why exactly this was so is somewhat obscure, since many K-T scenarios include intense acid rain that presumably would have strongly impacted freshwater environments.
The other point to note is that while the chelonians and crocodilians are often large they are also usually scavengers which increases survival odds following major catastrophes.