In Depth
Whenever you hear someone mention a ‘Sabre Toothed Tiger’, what they are really talking about, whether they realise it themselves or not, is Smilodon. This is because Smilodon does not belong to the same cat family as Tigers, which belong to the Pantherinae group. As a member of the Machairodontinae, a more acceptable generic name for Smilodon is ‘Sabre toothed cat’. This is not to be pedantic; it’s just about being factually correct so that people do not learn the wrong information.
Smilodon has a very wide expanse in the fossil record with the earliest species S. gracilis being known from the early Pleistocene till the Ionian stage about five-hundred-thousand years ago. Not only is S. gracilis the earliest species of Smilodon, it is also the smallest with weight estimates between 55 to a 100Kg.
S. fatalis is more intermediate in size with estimates of 160-280Kg. Its entry in the fossil record incorporates the final three sixths of Smilodon’s temporal range 1.6 million years ago near the start of Calabrian, till the early Holocene ten-thousand years ago. This overlaps the existence of S.gracilis by a little over one million years.
The largest and last species of Smilodon is S. populator, known in the fossil record from the upper part of the Calabrian till the early Holocene ten thousand years ago. Study of Smilodon remains also indicates that for a period of five-hundred-thousand years between the Calabrian and Ionian stages, all three species would have existed and been active at the same time as one another.
One interesting hunting theory is that Smilodon would lurk in the tree canopy waiting for a prey animal to walk underneath. Smilodon would then drop out of the trees and onto the animals back, sinking its teeth into it is neck before it even knew what had hit it. This is especially plausible for S. gracilis, as if its size estimates of 55-100 Kg are correct, it would be in roughly the same weight class as a modern leopard, a big cat which is known to spend a lot of time in trees.
However, S. populator was a much larger species of Smilodon, and as such would need either larger or more prey. With maximum weight estimates approaching half a metric ton , its large weight would also restrict its ability to drop from the trees. Although it may still have been able to drop from rocks which would be better able to support its weight, this still may have been a too passive method of hunting to support itself as a larger body would require more food to fuel it. For this reason it is highly likely it would at least on occasion switch to a different method of finding food. Large numbers of Smilodon have been recovered from the La Brea tar pits in California. In fact the recovered remains are in the hundreds, with an unknown number still waiting to be found. Smilodon would have been lured to this predator trap on the false promise of free food as other animals had become stuck and began struggling and calling out in distress. Many carnivorous animals, not just Smilodon, ended up getting stuck themselves as indicated by the vast numbers and types of remains.
This indicates that Smilodon like other predators was not above scavenging, either at La Brea or other locations. This does not mean that Smilodon was just a scavenger, in fact cats from the largest Tigers to the smallest domestic house cats are all active predators, which is why even well fed pets will still kill birds and bring them back to their owners.
While direct fossil evidence has not been found, Smilodon are sometimes envisioned as being pack hunters in a similar fashion to modern day lions. Although perhaps not the fastest of runners, two or three Smilodon jumping upon a large prey item could have used their combined strength and body weights to wrestle their prey to the ground. Once restrained, one of the Smilodon would then be able to finish the prey off with a bite to the neck, severing the arteries and closing the windpipe.
Although the large ‘sabre teeth’ of Smilodon appear to be devastating weapons, they were actually very fragile for canine teeth. Just as you can use a lever to magnify force to lift an object, the oversized teeth would also have been susceptible to magnified forces. Smilodon also had weaker jaw muscles than many other large cats that had smaller teeth, perhaps as an adaptation to reduce exposure to potentially teeth breaking stresses. However, weaker muscles would also allow Smilodon to open its mouth wider, and as we shall see, that is a vital adaptation.
A key feature of the jaws is the enormously wide gape. Compared to one of today’s lion’s that can open their mouths to 60 degrees, Smilodon could double this by opening its mouth to 120 degrees. Although impressive on paper, this is actually a very necessary adaption if it were to get full use of its teeth without also being handicapped by them. Considering that the teeth were up to 28centimetres long, the lower jaw would barely clear the bottom of the teeth if it could only open by 60 degrees. Smilodon may have also been a delicate eater due to the two larger teeth getting in the way of the smaller canine teeth. This would mean that Smilodon had to take smaller bites from a carcass as the large teeth were not suitable for tearing off large chunks. They may however have helped to hold bones in place while Smilodon chewed on them with its rear teeth, although the weaker jaw muscles probably meant that Smilodon did not spend much time trying to crack open bones.
Returning to the above proposal of pack hunting in Smilodon, there are two areas of support for this theory. The first is the paleopathology of Smilodon remains. Many of these specimens show signs of injuries to bones and the areas of muscle attachment that are so serious they would take weeks, and even months to heal, and would be enough to prevent a Smilodon from actively hunting. In solitary creatures these wounds would mean that the animal could not hunt and would actually starve to death, but many of the Smilodon specimens show that they healed. This means that the injured Smilodon had to get its food from somewhere while it recovered, and one explanation is that it was supported and fed by other members of the group. This behaviour can be observed in prides of lions today.
A second piece of support references a study of African carnivore reactions to the sounds of distressed animals. When the investigative team played back the sounds, they noticed that social carnivores would approach the sounds, whereas solitary ones would typically give them a wide birth. This suggests that when smaller carnivores hear the distress calls, they know that not only are larger carnivores coming to investigate, they are coming in their numbers too. A smaller carnivore is smart enough to know that if it goes to an area where large predators are not just present but numerous, it will likely end up being killed and eaten too. This scenario is quite plausible for the La Brea Tar Pits and the parallels that can be drawn between this study and the fossil evidence of la Brea, gives a very good indication to the social interaction of not just Smilodon, but other ancient predators such as dire wolves.
Further Reading
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