Everyone knows that the sabertooth “tiger” (Smilodon fatalis) had massive fangs — I can’t bring myself to call the big cat’s teeth canines — but its secret weapon was exceptional forelimb strength:
The sabertooth cat, Smilodon fatalis, was an enigmatic predator without a true living analog. Their elongate canine teeth were more vulnerable to fracture than those of modern felids, making it imperative for them to immobilize prey with their forelimbs when making a kill. As a result, their need for heavily muscled forelimbs likely exceeded that of modern felids and thus should be reflected in their skeletons.
[...]
Using radiographs of the sabertooth cat, Smilodon fatalis, 28 extant felid [cat] species, and the larger, extinct American lion Panthera atrox, we measured cross-sectional properties of the humerus [upper arm bone] and femur [thigh bone] to provide the first estimates of limb bone strength in bending and torsion.We found that the humeri of Smilodon were reinforced by cortical thickening to a greater degree than those observed in any living felid, or the much larger P. atrox. The femur of Smilodon also was thickened but not beyond the normal variation found in any other felid measured.
(Hat tip to io9.)