Stabbing It has been suggested that machairodonts used their saber teeth during hunting, grappling an animal, opening its mouth, and swinging its head down with enough force to puncture the animal's skin and flesh. It was once suggested that the saber teeth were used much like a
knife. For such reasons, this concept has been rejected by the scientific community.
Sexual characteristic , displaying extreme upper canines developed only through sexual selection and otherwise completely nonfunctional Long canines could also have been the product of
sexual selection, much like the mane of a lion, and were used for courting, sexual display, and social status. Their canines are already well established as relatively fragile, and their jaw muscles not strong, so any predatory function is uncertain. However, when a trait is adopted to enhance sexual attraction, typically only one sex, usually males, display the feature. In all machairodont species, both males and females have these canines and, with only minor exceptions as in
Machairodus, are shaped similarly. There is typically also a size difference between sexes, but male and female machairodonts appear to have been the same sizes. Also, this level of sexual selection seems extreme given an individual would be left severely impaired in eating and general function. The major drawback to these methods is that the large amount of blood spilled could be smelled by other nearby carnivores, such as other machairodonts or dire wolves. Predators often form competitive relationships in which dominance can shift from one species to the other, as seen in the modern lion and spotted hyena of Africa. In such situations, squabbles are not uncommon. The balance of power and dominance between these apex predators remains a mystery because of the social factor. Strength in numbers can be significant in these struggles. For example, dire wolves are thought to have traveled in small packs, and while individually subordinate, their numbers might have been sufficient to force a machairodont off a kill. However, the cat might have been able to scavenge on kills made by dire wolves. Two solitary machairodonts would quickly develop a pecking order with the first individual dominant. Because of this uncertainty, a large part of the
niche of machairodonts is still unknown. The several variations on this hypothesis all require a subdued and still animal.
General "bite and retreat" The first hypothesis involving the sensitive neck is that the cat simply restrained the animal and then bit the neck, without much specificity to location, to cause major blood damage and then retreated to allow the animal to bleed to death. Stipulations include not biting the back of the neck where contact with vertebrae could break the teeth, but a deep bite anywhere in the neck would prove fatal. This general bite would be used wherever it could be attained, and needs fewer predators. When compared with the belly-shearing hypothesis, one
Megantereon could kill a large deer, and possibly a horse, with little danger of breaking canines. This is because the bite can be applied while the carnivore keeps its body behind the prey for the most part, avoiding flinging legs while still pressing with its body weight to keep it still. It would have been a quick bite, suiting the ambush style of stalking and hunting implied by the heavy and strong bodies of most machairodonts. It would also have been possible for a lone machairodont to wound a large prey animal in this manner, then release and follow it until it fell from shock. The general bite-and-retreat hypothesis has been criticised because of its bloodiness and because the struggling prey would have attracted any predators and scavengers in the area. The idea that a single animal would wound, release, and follow a prey animal has been counteracted more strongly. Cats rarely walk away from prey until they have eaten their fill and it would have risked being stolen by other predators.
Xenosmilus in particular might have used this method, as all the teeth in its mouth were serrated and aligned in a way that formed a consistent cutting surface. '' applying the conical-tooth equivalent of the "bite and compress" to a
bushbuck.
"Bite and compress" When the animal is wounded with a bite from a machairodont (ignoring the placement of the blood vessels, which are negligible in this hypothesis), the canines would have been inserted behind the windpipe and the premolars would have been encompassing the
windpipe. This variation states that the machairodont compressed the windpipe after dealing the bite, serving to both suffocate and wound the prey animal. Puncturing large blood vessels in the throat and causing massive bleeding would hasten the death of the animal. Modern cats, and presumably the basal genera of all cats, such as
Pseudaelurus and
Proailurus, use the
throat clamp as a common method of dispatching prey. The suffocation would inhibit sound from the panicked prey, a method used by modern cheetahs and leopards. The wound from the canines and the lack of air would then kill the prey animal. This method might inhibit the full effect of the wound created by the canines. Keeping the canines in the wound would stifle the blood flow from the body and could keep the animal alive longer even if the prey is unable to vocalize. There is no significant advantage to the longer canines in this method of killing when compared to the ancestral cats with their short, conical-shaped canines. If anything, the dangers to breaking teeth held in the throat of a panicked animal, even if well restrained, outweighs the possible benefits, so this method has often been viewed as improbable. , pulled back and tore open the body. For this technique to work, a specific sequence of motions would have to be followed. First, the animal must be completely subdued, and the predatory machairodonts must be social, so that several individuals can hold the prey animal down. The individual preparing to deliver the killing bite would open its mouth at maximum gape, and with its mandible, press up on the skin of the belly. Creating a depression where the lower canines and incisors press into the skin, a slight fold is created in the skin above the lower teeth as the mandible is shoved upward. Next, the upper canines are pressed into the skin and the muscles of the neck are used to depress the head, so instead of pulling the jaw 'up', the skull is pressed 'down' . When the canines pierce the skin, they are lowered until the gape of the mouth is roughly 45°, where the mandible is pulled up in addition to the skull still being depressed. The small flanges on the anterior portion of the mandible of most machairodonts would be used to aid the depression of the skull. When the animal's mouth is closed, it holds a thick flap of skin between its jaws, behind its canines, and the animal uses the muscles of its lower back and forequarters to pull back, tearing the flap clear of the body. This large gash, once opened, leaves intestines uncovered and arteries and veins torn. The bleeding animal would die within minutes, and the shock of repeated bites, tearing innards from the body, could speed up the process. This method allows social machairodonts to inflict large wounds on prey animals. Massive blood loss would ensue, and though bloody, the social group would be able to fend off almost any animal attracted to the area. The bite would not need to be specific, and could be repeated to hasten the death of the animal, and it is already seen in the killing methods of several extant species, such as the spotted hyena. Canines are not as likely to be broken due to the softer nature of the abdomen when compared to the throat and jerking movements are not as amplified in the abdomen as they are in the neck. The abdominal-tearing hypothesis has generally been regarded as highly plausible. In the La Brea tar pits, occurrences of broken canines in
Smilodon are rare, and this less risky method might have contributed to this. However, a shearing bite may have been problematic for machairodonts for several reasons. Most
ungulates are highly sensitive around the belly and hindquarters, and most predators find it much easier to capture and subdue an animal similar to the domestic cow, by manipulating the head and forequarters. By lowering the animal to the ground and placing itself between the pairs of legs, a machairodont would have suffered great risk of being kicked. The power behind such a kick would easily break teeth, a mandible, or a leg, and cripple or kill the cat. Sociability might have solved this issue by having one individual deliver the killing bite while others held the animal still. Furthermore, the diameter of the abdomen of a large ungulate such as a bison might have been too large, and the skin too taut, for a machairodont to grasp a flap of skin at all, much less tear it away from the body. A third issue with the shearing bite is that the canines would need to tear a large hole in the belly of the animal to be successful, but might instead simply flay the skin and produce two long slits. This wound may be painful and bleed, but the animal likely would not bleed to death and could still escape and survive, instead of bleeding to death. In 2004 an experiment used a pair of mechanical aluminum jaws, cast from the CT scans of a
Smilodon fatalis from the La Brea tar pits, to simulate several biting techniques possibly used by
Smilodon, including the shearing bite, on a fresh domestic cow carcass. The belly of the cow was found to be too large in diameter for the canines to puncture the skin, which were instead deflected off the body, with the mandible blocking their access. However, the model pulled its jaw upward as modern cats bite, while machairodonts most likely did not, instead pressing their skulls down with the aid of their neck muscles. This flaw in the procedure might nullify the results and leave the belly-shearing hypothesis untouched. ==Notes and references==