Ancient saber-toothed cats not only had teeth that put the choppers of modern big cats to shame, they grew them a lot faster, a new study says.
Loping across North and South America from about 700,000 years to 11,000 years ago, saber-toothed cats — Smilodon fatalis — could rip into large prey, including bison or camels with upper canine teeth as long as seven inches.
They could also grow them to that length quickly, according to a study published in PLOS One.
Scientists analyzing scans of fossilized saber-toothed skulls in the La Brea Tar Pits in Los Angeles say the big cats' permanent canine teeth grew in at about almost a quarter of an inch per month, twice as fast as a modern day African lion grows its teeth.
Paleontologists say Smilodon probably used its outsized canines to bite into a prey animal's neck and sever arteries and veins there for a quick kill.
Saber-toothed cats were about the same size as a modern-day lion or tiger but with heavier builds, leaping on their prey and holding on with powerful limbs.
"Basically a lion on steroids with knives coming out of its mouth," says paleontologist Z. Jack Tseng of the American Museum of Natural History in New York, a co-author of the study.
"Baby saber" teeth would precede those "knives," the researchers said. They would be shed by around 1-1/2 years of age, with the permanent canine teeth fully grown by about 3-1/2 years of age. There would be an overlap before the shedding of the baby teeth, the researchers suggest, and for several months, saber-toothed cubs would have a mouth featuring both sets of sabers.
The fast growth of the adult canine teeth would have allowed saber-toothed cats to be proficient hunters at a young age, says study lead author Aleksander Wysocki, a graduate student at Clemson University.
"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," he explains.
However, fossils of saber-toothed cats younger than four to seven months are conspicuous by their absence from the La Brea collections, the researchers note.
Wysocki suggests one possible reason.
"Considering the abundance of predators at Rancho La Brea, younger cubs would have been at risk of being preyed upon themselves if they attempted to feed on the animals trapped within the tar pits," he says. "The cubs probably remained hidden or at den sites while the adults pursued prey trapped in the tar pits and never made it back out."
