A partially fossilized jaw from an adult Smilodon fatalis saber-toothed cat showing a fully erupted canine is pictured in this undated handout photo courtesy of the American Museum of Natural History (AMNH), obtained by Reuters on July 1, 2015. REUTERS/AMNH/J. Tseng/Handout via Reuters

The saber-toothed cat, which roamed what are now the streets of Hollywood until about 10,000 years ago, is the stuff of legends. A menacing predator with gigantic, fearsome canine teeth, it would have been a scourge to any prey animal that encountered it – including early humans. The spectre of the saber-toothed cat has been over-hyped in popular culture, but is it possible it really was as fearsome as it seems? The answer is yes, according to a new analysis.

Smilodon was “basically a lion on steroids with knives coming out of its mouth,” said paleontologist Z. Jack Tseng of the American Museum of Natural History in New York.

The study, published in the journal PLOS ONE, involved an analysis of oxygen isotopes left behind in the enamel of a fossilized tooth found in the La Brea Tar Pits. The analysis revealed a few surprising insights into the lives of saber-toothed cats. For one thing, they weren’t born with those massive canines – they had so-called baby teeth for the first year and a half of their lives, with the adult teeth taking about three years to grow in completely.

Smilodon’s canines were seven-inch, serrated killing tools, but their size also made them somewhat fragile. That’s ok, however, because the researchers also determined that the canine teeth grew at a rate of about a quarter of an inch per month. That’s faster than a lion or tiger’s teeth grow, and even faster than human fingernails.

“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 Tseng. “This is especially crucial for understanding sabertoothed predators such as Smilodon.”

Speaking of lions and tigers, Smilodon had a similarly sized frame, though it’s believed to have been much more muscular than modern big cats. With it’s stout, powerful build, it would have pounced on and overpowered prey, using its large canines to quickly sever crucial arteries in the neck.

In the future, scientists hope the method used to analyze the teeth of saber-toothed cats can also be applied to determine the growth rate of other animals, like elephants and marine animals.