Sabre-toothed cat's teeth grew twice as fast as modern lions'


The fossilised jaw of an adult Smilodon fatalis shows the fully erupted canine.
© AMNH/J. TSENG

The terrifying, dagger-like teeth of the sabre-toothed cat Smilodon fatal is grew at twice the rate of those of modern big cats, a new study has found.

However, the teeth in the prehistoric species emerged later in life and even despite their relatively fast growth-rate, the canine teeth were not fully developed until the cat was three years old.

The findings, published today in the journal PLOS ONE, are based on a new technique that combines isotopic analysis and x-ray imaging. It provides for the first time specific ages for developmental events in Smilodon, notably in their teeth.

The study estimates that the eruption rate of permanent upper canines was six millimeters a month – double the growth rate of an African lion's 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 National Science Foundation and Frick Postdoctoral Fellow in the American Museum of Natural History's Division of Paleontology and a coauthor on the new paper.

"This is especially crucial for understanding sabre-toothed predators such as Smilodon."

S. fatalis lived in North and South America until going extinct about 10,000 years ago. About the size of a modern tiger or lion but more solidly built, the cats are famous for their protruding canines, which could grow to be 18 centimeters (about 7 inches) long. Although well-preserved fossils of S. fatalis are available to researchers, very little is known about the absolute ages at which the animals reached key developmental stages.

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