Saber toothed tigers are some of the most famous and plentiful prehistoric fossils found today, yet little is known about how they actually lived. Sabers, also known by their scientific name Smilodon fatalis, are second only to the dire wolves as the most common animal found in the La Brea Tar pits in Los Angeles, California. Other species of saber toothed cats existed all over the world, but this particular species of the big cat prowled the southwestern United States until about 10,000 years ago. Smilodon and its relatives are most famous for their massive fangs that can stretch to a length exceeding 7 inches. A recent study in PLoS One investigated  all ages of Smilodon skulls found in the tar pits, and has uncovered surprising data into the rate at which these big saber teeth grew.

It is common knowledge that as kids grow up, they lose baby teeth that are then replaced by adult teeth that had grown in underneath them. Unsurprisingly, the same happens with most mammals, including the prehistoric Smilodon. The big cats’ molars, and shredding teeth called carnassials, are replaced in the same fashion as other mammals, but their canines (the saber teeth) have a unique way of erupting.

In most big cats, such as tigers and lions, the baby teeth grow inside the womb and under the gums. This is also assumed to be the same in  Smilodon. The differences in these animals starts after birth when the teeth begin to emerge from the gums. In big cats the deciduous teeth, what we call baby teeth, grow in fully before most of these animals are 3 months of age. In Smilodon the deciduous teeth, excluding the canines, grow in at 4-7 months but the canines don’t fully emerge until 11-18 months of age. When we move onto the adult teeth the same large gap between not only species but types of teeth is also seen in Smilodon. Modern cats of the same size were again used for the adult teeth and it was found that molars and carnassials are finished growing in at 24 months, while canines finished fully developing at a maximum age of 36 months. The growth of the adult carnassials and molars in Smilodon are finished by 22 months. The canines took an extra 3 or more months to grow in and a further 20 to become full sized at around 40 months or age. This shocking  difference in tooth growth between the canines compared to the molars and carnassials was investigated further using specimens of Smilodon with a wide variety of canine growth stages.

Saber tooth with partially erupted adult canine.

Saber tooth with partially erupted adult canine. Image from Wysocki et al. 2015.

 

When the specimens had been thoroughly examined by Wysocki and his team at Clemson University, it was seen that Smilodon had a retention of the deciduous canines while the permanent ones were growing in. This means that the cats had four upper canines at the same time! This is seen somewhat with big cats such as lions, but the baby teeth are only present for a few months while the adult teeth grow in. When we look at Smilodon the older canines remain in place for nearly a year while the saber teeth grow in. Interestingly enough, research suggests that the reason for such a long period of time with both deciduous and permanent teeth in the mouth is to protect the long saber teeth from injury, such as a fracture or break during growth. Because the adult teeth take much longer to grow than all the other teeth, having support alongside the emerging tooth would be advantageous for shielding them.

Young saber tooth with adult canines erupting behind (left) the baby tooth. AMNH Tseng 2015.

Young saber tooth with adult canines erupting behind (left) the baby tooth. AMNH Tseng 2015.

Another curiosity that the research team stumbled upon while looking into the specimens of Smilodon was that there was an age cut off of about 7 months in the records. Very young animals such as cubs appear very seldom or not at all in the pits. La Brea is known to be a death trap for predators who try to attack animals stuck in the tar and in turn cause their own deaths. The cats that are found caught in these pits are usually adults or subadults. This suggests that the cats hunted away from dens or sites where the cubs were kept and brought food back to them, much like the big cats of today do. It also supports the theory that the deciduous canines remained in place while the adult teeth grew in. Why? Because with the saber teeth being weakened while growing in, the young cat would be unable to hunt on its own for risk of breaking the teeth. Maternal or pack care would ensure that little possibility of injury could  be risked to the young by bringing the carcass to the cubs, instead of bringing the cubs to the carcass. If the latter were true the likelihood of finding cubs in the tar would have risen. By bringing food to the cubs while they were young it gave the cubs enough time for their saber teeth to grow in before they hunted alone.

The growth of these unique saber teeth was both fast for the length of the teeth but slow in comparison to modern felines of similar size and build. It’s also amazing to think that just by cubs not being present in a tar pit that scientists can conclude behavioral aspects of the Smilodon’s maternal care. All of these new discoveries have led to a different view of this big cat that could, in turn, lead to further investigation into how they lived. This American saber tooth may not be around anymore, but that hasn’t stopped scientists from wanting to learn more about them.

Published On: August 28, 2015

Cienna Lyon

Cienna Lyon

Cienna Lyon is a student at Ithaca College in New York studying Biology and German and a volunteer science writer for the Paleontological Research Institute. She works in a lab with Te-Wen Lo on genetic research and at the Whalen Center for Music which are both on the Ithaca College campus. She spends her free time playing the french horn in several on campus musical ensembles or getting up to date with all the new paleontological discoveries as becoming a theropod paleontologist is her end goal.

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