[HarHarVeryFunny]

There's a video on YouTube by a paleontologist giving his own theory for why sabre-tooth cats had these teeth which would be more hindrance then help in the kind of use most people imagine for them. Fossils show they couldn't open their jaws wide enough to use these teeth in stabbing fashion, except on something very thin.

The theory is that the sabre-tooths evolved to specialize in feeding on long-necked camelids (camel family) and the teeth evolved to let them deliver a fatal slicing bite to the neck. The sabre-tooths teeth fit neatly between the neck vertebra of a camelid, and have serated edges to let them slice through the tissue - the teeth are made for slicing, not stabbing (edit: as much as specialized stabbing).

Being so specialized they likely went extinct when their prey did (for whatever reason).

[im3w1l]

Serrated knives are for back and forth sawing, not slicing. Would the same go for a serrated tooth?

[HarHarVeryFunny]

Yes, but if you imagine the dynamics, the cat chomps down on the prey's neck (which unlike anywhere else is narrow enough that it can open it's jaws wide enough to stab through) and just the natural struggle would let the serrations do their work. The cat wouldn't need to cut all the way through the neck - as soon as the arteries are cut then the prey will weaken and bleed out, which seems to be a fairly common MO among some predators.