Wouldn't other animals with strong bites be capable of crushing bones to eat the marrow inside? The theory is big on assumptions, but I guess that's how it goes when you're trying to figure out what happened millions of years ago.
Some animals like snakes simply swallow prey whole. Dogs and pigs are known for eating hastily with minimal chewing, and I'd imagine many other predators are the same. No idea how efficiently their respective digestive systems extract nutrients from solid mammal chunks.
I was under the impression that it had more to do with lips than jaws. Hyenas can outbite humans a thousand times over, but they can't drink a milkshake through a straw!
In other words, breaking bones is the easy part; sucking out the marrow is the tricky bit.
Hyenas are known to eat bone. The bearded vulture is the only known bird that eats bone marrow, and cracks open bones by dropping them on rocks from a great height.
