Sabertooth cats...

...were bad, bad, animals.  Four feet tall at the shoulder, and armed with foot-long serrated canines (in the case of Smilodon populator, the largest of the group).  And, apparently, massively strong in the forelimbs.  X-ray analysis reveals that the bones from the front legs of sabertooths were dramatically thicker, and presumably stronger, than those of similarly-sized modern cats.  The cats apparently used their powerful forelimbs to hold down their prey while they dispatched them with the canines.