How can you distinguish Plesiosaur teeth from Crocodile teeth?

[Mosasaurhunter]

Hello, how can you distinguish plesiosaur teeth from crocodile teeth. Sometimes I hear about people confusing plesiosaur teeth with crocodile teeth like those from Thoracosaurus. I was wondering how you can tell one from another.

[North]

First thing I would check is carinae, since plesiosaurs lack it and crocodiliforms usually have it.

[Jaybot]

But sometimes crocodiliforms don't have carinae, and crocodiliforms and plesiosaurs have apicobasal ridges, right?

Newbie to this. Just trying to learn