[AutumnBison (OP)]

• Since Walking with Beasts, is the "love-hook" idea of the smaller back legs still a valid explanation?  Or have others been brought up over the years?
• How on Earth can you fit a population of 65-foot-long, multiton predators like Basilosaurus in habitat as dense, shallow and unstable as a mangrove swamp?

[OokieWonderslug]

You probably can't. But you can wash a few in with a hurricane where they die upon being stuck in the quagmire of a mangrove swamp. Fossils rarely show where a fossil lived. They show where they die.

[evan_au]

It appears that Basilosaurus was a large predatory whale (marine mammal), rather than a dinosaur.

Mangrove swamps can cover a large area, but they don't survive in the deep water that would be an ideal environment for a whale-like creature.

So maybe it was an early mass beaching?

See: https://en.wikipedia.org/wiki/Basilosaurus