The Smilodon fatalis, one of the more well-known and studied saber-toothed cats, lived in the Americas until about 10,000 years ago. This week, a new paper was published that looked at how long it took Smilodon to fully grow its trademark teeth.

“For predators such as big cats, an important determinant of an individual’s full hunting ability is the time required to grow their weapons—their teeth,” said Z. Jack Tseng, a co-author on the new paper. “This is especially crucial for understanding sabertoothed predators such as Smilodon.”

Tseng and his colleagues estimate the growth rate of Smilodon fatalis’ upper canines was 6 millimeters per month. That’s double the growth rate of a modern African lion. The saber-toothed cat’s teeth grew until it was about three years old, and each one measured nearly 7 inches long.

smilodon fatalis canine

Just like many other mammals, Smilodon had two sets of teeth in its lifetime. The first set stopped growing at about one-and-a-half years old. The permanent pair started growing around this time. By the time a Smilodon cub hit 20 months, the baby teeth were gone and the permanent set of canines continued to grow.

That is later than today’s large cats, but its teeth were also much longer.

“Despite having canine crown heights that were more than twice those of the lion, Smilodon didn’t require twice as much time to develop its canines,” said Aleksander Wysocki,

How researchers figured out the growth rate of Smilodon’s canines

Despite recovering several well-preserved fossils of Smilodon fatalis, little was known about the exact timing the animals reached certain developmental stages – such as fully grown canines.

Researchers tackled this problem by combining data from stable oxygen isotope analyses and micro-computed tomography to get a clear picture of the growth rate of the saber-toothed cat’s upper canines.

The researchers were then able to nail down the time-frame for how long it took Smilodon’s canines to fully grow.

Robert Feranec, who also worked on the study, said, “this technique will permit the determination of absolute developmental age not only for Smilodon, but other extinct species.”

According to researchers, this technique would be especially useful for determining growth rates in extinct elephants by looking at their tusks.

The life of a Smilodon

Smilodon is famous for its long upper canines, but their use might surprise you. The teeth were fragile, and the cat risked breaking them biting into bone. Instead, researchers believe the Smilodon would first wrestle their prey to the ground first before stabbing their upper canines through the prey’s throat.

Another hypothesis suggests the Smilodon may have aimed its large teeth at the chest of its prey to puncture its lungs.

The main prey for these saber-toothed cats included bison, mammoths and other large mammals. Smilodon is believed to have lived in forests and primarily ambushed its prey.

Researchers don’t have a definitive answer for why Smilodon went extinct 10,000 years ago. One theory points to the extinction of large herbivores, the cat’s primary food source. Other theories suggest competition with humans.

The paper was published yesterday in the journal PLOS ONE.

Featured image credit: Momotarou2012/Wikipedia

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