The killing bite

The nature of the killing bite has puzzled palaeontologists for years. First, where was the bite best placed? Abdomen? Neck? Throat? And second, how was the actual kill made? Was it by massive blood loss due to repeated bites, or by a single crushing bite (as is typical of modern big cats)? Recent studies of tooth fracture frequency in felids, and a better understanding of sabre-tooth cat anatomy, have led to greater agreement concerning the killing bite.

The choice of where to place the killing bite was probably determined largely by the need to immobilize potentially dangerous prey as quickly as possible without breaking the slender upper canines. A sabre without its distal third or half would lose much of its tapered shape, making it much more difficult to drive through skin and muscle. By contrast, because modern big cats often kill by strangling or suffocating prey, their conical teeth can produce death grips even when blunted. A study of modern lions revealed that many individuals survived for years with at least one broken canine tooth. Based on the large sample of carnivores preserved in the Rancho La Brea tar pits of California, it

Killing Bite
Fig. 4.1.15.2 Canine-shear killing bite of Smilodon, as proposed by Akersten (1985). (From The big cats and their fossil relatives, by Alan Turner and Mauricio Anton (Contributor) © 1997, Columbia University Press. Reprinted with the permission of the publisher.)

is clear that Smilodon broke its canines regularly, but less frequently than the large lion (Panthera atrox) with which it coexisted (Van Valkenburgh and Hertel 1993). To avoid canine fracture, sabre-tooths would have directed their bites toward areas of the body where contact with bone was unlikely. Two areas appear best: the abdomen and the ventral throat. The throat was probably preferred because a bite there could more easily sever critical vessels and nerves. In addition, the abdomen might be more problematic because it is partially obstructed by the hindlimb of the prey and the large ribcage that is typical of herbivores. In either case, sabre-tooths would have held prey immobile or nearly so with their heavily muscled forelimbs and protracted claws while they applied their canines to make the kill.

The bite itself would have depended on a strong downward pull on the cranium to drive the upper canines through the throat while the lower jaw was pulled upwards. The canines and enlarged incisors could work together to pinch a sizeable fold of flesh (Fig. 4.1.15.2) that would then be removed by a rearward pull of the head (Akersten 1985). The necks of sabre-tooth cats tend to be long and heavily muscled and were no doubt important in stabilizing the head during the killing bite as well as pulling backwards and downwards. The bite strength of a sabre-tooth was likely greater than that of living big cats. A recent study of the cross-sectional geometry of the mandible of Smilodon revealed it to be similar in strength and rigidity to that of living spotted hyaenas, animals that are known for their powerful bone-cracking jaws (Biknevicius and Van Valkenburgh 1996). Whether the kill required a single bite or multiple bites may have depended on the size of the prey. A smaller sabre-tooth taking a very large prey might need to use several bites to produce the necessary blood loss or sever the trachea. Although it is possible that sabre-tooth cats could have used a stranglehold, as do modern big cats, this seems unlikely, given the knifelike nature of their canine and incisor teeth. These were teeth shaped for slashing and ripping, rather than crushing and holding.

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