As air–breathing mammals, whales must once have lived on land and needed hind limbs capable of supporting the mammals...

Emil-Kunkin on January 28, 2023

Hi,

A supports the idea that whales used to have hind limbs because it tells us that older whales had a pelvis, and the argument tells us that animals with a pelvis should have legs. Thus, if whales had a pelvis, then we would have expected them to have hind legs.

I think D actually weakens the argument. If it tells us that other marine mammals are able to live on land without legs, then it undermines the idea that ancient whales would have needed legs to live on land.