Smilodons What We Know About

Smilodons

What we know About Smilodon

The smilodon is one of the most interesting predators of the Pleistocene era. Studying and habits of large predators can give us many clues as to the biodynamics of an area. The largest collection of smilodon fossils is in the tar pits near the city of present day Los Angeles. Many of the early ideals about the smilodon are no longer held to be valid. As technological advances allow us to gain a better understanding of the fossils themselves and more data is collected from a larger pool of specimens, many of the ideas about the smilodon have changed. The most remarkable finding from this research is that the smilodon was not a social animal as was once thought, but that they hunted as solitary individuals.

What we know about Smilodon

The Smilodon, mistakenly called the sabre-toothed tiger by the uninitiated, is one of the more interesting creatures of the Pleistocene. The most prominent feature of this cat-like creature is exceptionally large set of front incisors. There are many controversies concerning Smilodon from the use of those enormous teeth to social behaviors and the prevalence of arthritis. This research will explore research from the time of discovery of Smilodon to present studies on DNA.

Smilodon is a member of the Felidae family. There are six recognized sub-species of Smilodon: Smilodon californicus, Smilodon fatalis, Smilodon gracilis, Smilodon populator, Smilodon floridus, and Smilodon neogaeus (Radinsky and Emerson). These cats populated North and South America throughout the Pleistocene period. They are generally thought to have ranged from 1 million to 10,000 years ago, with some species reported to be as old as 500,000 years (Radinsky and Emerson).

A majority of what we know about Smilodon is a result of research at the La Brea Tar Pits in Los Angeles, California. The prevalence of these fossil remains in the area resulted in the Smilodon becoming recognized as the official California fossil. Data from this area is changing the way we think about smilodons. There have been several ideas about social behavior and the style of attack that have fallen out of favor as a result of research coming from this tar pit.

The skull of Smilodon, the state fossil of California, on display at the Fryxell Geology Museum of Augustana College. Source Official Dino Land State Fossils. http://www.geocities.com/stegob/smilodoncalifornia.html

They are thought to have weighed approximately 450 pounds, had a short tail, powerful legs and a disproportionately large head. One of the most remarkable aspects of the cat was its ability to open its jaws 120 degrees (Radinsky and Emerson). This allowed it to use its 7" long fangs. However, exactly how the animal used this ability is a controversial topic among scholars. Some believe that the large front teeth were used to hold prey. However, it is suspected this type of grappling would have broken the teeth.

The fossil record indicates that there are few with broken front teeth. Therefore, the teeth were likely used for a different purpose. Another theory exists which proposes the idea that the smilodon used its front teeth to produce a fatal wound in the stomach or throat. It has been suggested that rather than struggle with the prey, smilodon simply waited for the animal to die from the fatal blow. This is the most plausible scenario as it is the most consistent with morphological characteristics of the saber-tooths themselves.

Modern lions, cheetahs and other large cats use their tails to provide balance while they propel themselves at high rates of speed in pursuit of prey. Smilodon had a short, bobbed tail, suggesting that it may not have chased prey as modern animals do. It may have laid in wait until an animal passed by. Modern cats use ambush techniques similar to what many think the smilodon may have used.

Social or Solitary

Of the most intriguing of the arguments regarding smilodon is how social behavior was managed in the group. Smilodon lived a rough life as many of fossils found in the La Brea Tar Pits had broken bones and signs of bone regrowth. This is one of the key arguments for the existence of social behavior. Some have suggested that other smilodons took care of the wounded animal. However, is just conjecture. It could be suggested that these healed bones are indicative of social behavior, but for a different reason.

The hurt animal would have been unable to hunt and provide food for it long enough for bones to heal. Solitary animals often die of starvation when they suffer a crippling injury. In order to prevent starvation smilodon would have had to have others to provide food for them while they healed. This is the most logical angle to argue social behavior based on bone injuries. However, much of the argument in scholarly texts uses the healing argument to support the existence of social behavior. The ability to "doctor" an injured animal is much more complex than if other members simply provided food for the injured animal. This is the more plausible explanation of social behavior.

The most popular standpoint on the smilodon is that they lived together much as modern lion prides do today. However, as one will see, there is an overwhelming amount of evidence that suggests that smilodon was a solitary hunter like a cheetah. There is one possibility that has not been considered in the literature that was found, but one that is worth mentioning. There are six different species of smilodon thus far. Some of them have longer front legs that are suitable for sprinting like a cheetah. Others have shorter, stronger legs like a modern lion. To date no one had performed a comparison that examines the traits used to study social behavior according to the different species. Perhaps there are differences in social patterns that correlate to differences in physical features as well. This may pose an interesting question for future research.

Other injuries found on the skeletons suggest that they were injured by other cats. Modern large cats fight over food and mates. If smilodon were social, then it is likely that they fought in a similar manner. We know that the smilodon could roar due to the structure of the hyoid bone. The evidence suggests that the pack life of smilodon was much like that of modern lions and other carnivorous groups of cats.

This theory is stated in many research articles regarding smilodon social habits. However, not every one agrees that healed bones are evidence of social behavior. McCall, Naples, and Martin refute the thesis that smilodon was social based on healed bones. In their work, they provide a detailed analysis that refutes many popular theories on smilodon behavior. Their primary argument against the social cat theory is that the cats use metabolic reserves to heal quickly without feeding. The second is that dehydration is a more difficult to obtain when injured and much more critical to survival. They will die of dehydration long before they starve to death. According to McCall, Naples, and Martin, a carcass only provides one quarter of the water necessary for survival.

McCall, Naples, and Martin offered several other arguments against the social nature of the smilodon. The smilodon's brain size was small in comparison to their body. Social behavior is typically not found in animals with this small of a brain. The connection between brain size and the social nature of animals is a generally accepted principle. One would not expect to see social behavior in a brain as small as the smilodon's. This would indicate that much of smilodons' day was spent in the pursuit of food.

The physical fact that they were found in the tar pit is indicative of some type of locomotion after injury. Other researchers have argued that the number of smilodons found in the tar pits is evidence that they were social. However, this is also refuted by McCall, Naples, and Martin. They do not feel that this is indicative of social behavior, but rather the result of singular hunters tracking an easy pry. They note that other solitary hunters are found at the tar pit in numbers similar to the smilodon. Among them is the Golden eagle. On the contrary, social species, such as grey wolf (Canis lupus) and Coyote (Canis latrans) are rare.

Robert Feranec disputes the idea that the longer canines took a longer than normal time to grow. According to the authors if this were true, youths would not be able to hunt and sustain themselves. Therefore, the canines had to be in place. This theory is another stike against the social nature of the cats. If the canines grew much slower than the other teeth then the youth would have to depend on a social group to hunt and provide them with the food that they needed.

When one considers both sides of the social argument, it would appear that the non-social argument posed by McCall, Naples, and Martin is based on hard evidence and data. Therefore, it would tend to hold more credibility. Social theories based on bone breakage were based on theory alone. When one considers the merits of these two conflicting theories, one has to examine the behaviors and condition of modern animals, especially when making such general statements.

If one considers what happens to modern animals when they are hurt, the non-social theory would have more support. Dehydration would be the most critical factor in death after an injury. However, one flaw in this theory is that they gave no comparison of evidence to support their supposition that the animals could live on their body mass while healing. There is simply not enough known about the metabolism of the smilodon to make such as suggestion. Overall, the theories of McCall, Naples, and Martin hold more credibility than the social theories, save for the one exception.

Genetics and DNA

Several researchers were able to extract and clone DNA from the fossil bones of three different smilodons from the tar pits. They found that the smilodon is related to 15 known modern species including 9 species of cat and 6 non-feline species. This confirmed the theories that smilodon was distinct from the saber toothed cat that appeared during the Miocene period (Janczewsi and associates). The most important result that came from this study was that we now know it is possible to clone DNA and obtain valuable information.

Examining the fine structures on the large maxillary tells us that the tooth had the capability of providing sensory information to the brain (Riviere and Wheeler). Martin, Bariarz, Naples, and Hearst discussed the emergence of a new species found in Florida that had a different tooth shape than other saber-toothed cats. The canines of smilodons were different. Many of the cats in North America are known as the longer dirk-tooth. That is two finely serrated canines. These cats had short legs that were built for power rather than speed. Other cats had shorter scimitar-shaped canines and longer legs for speed. The new species found in Florida has the scimitar-tooth as well as the short limbs of the dirk-tooth cat (Slaughter, 486-492).

As far as body mass is concerned, three different species were examined (Christiansen and Harris). Based on variables from the skeletons of modern cats it was found that'd. gracilis is more comparable to the size of a modern jaguar. S fatalis was found to be somewhere close to the frame of a Siberian tiger. S. populator was larger and heavier than any living cat. Some exceptionally large specimens of S. populator have been recovered. According to the authors previous estimates were low due to a lack of data.

How the Smilodon Attacked

Rosie and Winters consulted with personnel from Rancho La Brea and the Idaho Museum of Natural History regarding many aspects of the smilodon. When one examines the plant matter found on herbivores it paints a picture of what smilodon's world would have been like. The area was a plain with patches of sagebrush, buckwheat, oak and pine. According to the authors, this would have made an excellent hiding place for the smilodon to stalk its prey.

When stalking its prey, the smilodon often injured itself and pulled soft tissues. The scars of these tissues bear the scars of these injuries. According to Rosie and Winters, the most common position for the body of a smilodon to be in when it attacked was feet forward in a lunge. This would suggest that smilodon would spring onto its prey. This theory was derived from data obtained by counting the number and location of injuries in the fossil record. It might be noted that when one compared the injuries of smilodon to canine species, there were fewer injuries from being kicked in the head. This would indicate that canine species attacked by lunging at the throat or hind quarters, whereas the smilodon landed on top of the animal's back and tried to bowl it over.

According to Rose and Winter, the smilodon's tooth was suited more for ripping a belly than sinking deep into the back. In this article William Akersten, former Rancho La Brea curator, this is similar to the manner in which a komodo dragon attacks. He explains that the saber-teeth are more suited for a forward and backward motion. Animals that attacked by biting the neck would need to be able to go side to side. There are surprisingly few broken saber teeth found. This injury was apparently rare. If the smilodon would have attacked and tried to bite the neck, one would expect to see many more broken teeth as they hit the harder bones of the bigger animal.

Ayonge (1059-1067) examined the molars and wear patterns and compared them to wear patterns on modern animals such as canids and other felids. They found that the wear patterns of S. fatalis were not consistent with the canine teeth of six large carnivores including leopard, panther, cheetah, African lion, spotted hyaena, Crocuta; African wild dog, Lycaon pictus; and Canis lupus. They concluded from this evidence that the diet and killing pattern differed significantly from those of modern animals. They too support theory that smilodon did not come into contact with bone while killing or feeding.