Smilodon, the Saber-Toothed Wrestler

Two things are remarkable about the bones of the predators we call Saber Toothed Cats: the size of their canine teeth, and the size of their arm bones. Compared to modern cats like lions and tigers, they had massively muscled chests and front legs. Why?

Probably because they attacked their prey differently than modern cats:

Smilodon used its huge teeth in a very different way to its modern relatives. Living cats use their jaws to close the throat or nose of their prey, choking them to death. Their conical canines are well-suited to the task, able to withstand forces in all directions. Sabre-teeth, while they look formidable, were actually quite fragile. They were long and flattened, rather than short and conical. If the cat’s prey struggled, its teeth would have shattered. If the teeth hit bone during a bite, they would have shattered. So Smilodon used the sabres like an assassin’s dagger rather than a swordsman’s blade, dispatching victims with quick stabs. Its big arms helped it to restrain its prey for the killing blow.

Smilodons and similar beasts probably specialized in attacking very large prey; the massive muscles that made them strong enough to take on mastodons made them too slow to chase deer or pounce on rabbits. Which may explain why they went extinct when the giant mammals of the Americas died out.