[shantly]

Fossilization of bone generally requires animals to die such that they're buried pretty quickly. The swampier parts of swamps, river banks, tar pits, that sort of thing. Risky areas for megafauna, not places they're going to be, say, sleeping if they can avoid it. The exceptions are when there were, for example, flash floods that quickly swept & covered ordinarily-safe-and-fertile flood plains, or when predators dragged carcasses to such places for whatever reason (big crocodiles, maybe), volcanic eruptions, stuff like that. A large land animal killed not by some disaster, that ended up fossilized, probably didn't die of old age or of predation by something common to the animal's preferred habitat, unless they were (for example) swamp dwellers to begin with.

[edit]

> Are they trying to claim that females who die are less likley to turn into fossils, perhaps because of the locations the deaths occurred in?

Yes, I think that's it.