Contrary to the popular explanations for the extinction of saber-toothed cats, new fossil evidence suggests that they did not die out due to a lack of prey. Researchers say that even near extinction, saber-toothed cats likely had enough to eat.
Saber-toothed cats, as well as American lions, woolly mammoths and other giant creates once roamed what is now known as the United States of America, but at the end of the late Pleistocene about 12,000 years ago, these so-called "megafauna" went extinct. This die-off is known as the Quaternary extinction.
Researcher Larisa DeSantis, a vertebrate paleontologist at Vanderbilt University in Nashville, said:
"The popular theory for the megafaunal extinction is that either the changing climate at the end of the last ice age or human activity, or some combination of the two, killed off most of the large mammal. In the case of the great cats, we expect that it would have been increasingly difficult for them to find prey, especially if had to compete with humans. We know that when food becomes scarce, carnivores like the great cats tend to consume more of the carcasses they kill. If they spent more time chomping on bones, it should cause detectable changes in the wear patterns on their teeth."
Researchers thus analyzed the fossil teeth of 15 saber-toothed cats and 15 American lions that were recovered from the La Brea tar pits in Los Angeles. The specimens ranged from 11,500 to 35,000 years in age.
The researchers used dental microwear texture analysis to study the fossils. This process involves generating three-dimensional images of a tooth's surface. The image is then analyzed for microscopic grooves. The devouring of red meat produces small parallel scratches, while biting on bones leads to larger, deeper pits.
The analysis of the teeth found that the wear pattern on the teeth of the saber-toothed cat most closely resembled those of present day African lions, which sometimes crush bone when they eat. The wear pattern of American lion teeth were similar to that of the present day cheetah, which deliberately avoids bones when it eats.
Analysis of older fossils and more recent ones did not reveal any evidence that patterns of wear changed over time. None of the specimens had extreme microwear such as living hyenas, which consume entire carcasses, bones included.
The analysis of the fossil teeth suggests that the prey for saber-toothed cats was not scarce, and that the animals were not gnawing their victims to the bone.
"Tooth wear patterns suggest that these cats were not desperately consuming entire carcasses, as was expected, and instead seemed to be living the 'good life' during the late Pleistocene, at least up until the very end."
Previously, research of teeth from American lions, saber-tooth cats, dire wolves, and coyotes from La Brea revealed that they experienced three times the number of broken teeth as their contemporary predators. This suggested that they may have been having trouble finding prey, and were subsequently devouring whole carcasses. Scientists then began to suspect that climate change and human competition were making life difficult for the large predators.
DeSantis and her colleagues, however, argue that this high rate of damage seen in teeth more likely resulted during the capture of prey rather than feeding on carcasses:
"We expected extinct carnivores to show evidence for extreme bone processing, based on the high number of broken teeth determined from prior research. Finding the complete opposite pattern was shocking!"
Saber-toothed cats were about the size of the modern African lion, and the American lion was about 25 percent larger. Both fed on giants like mammoths and giant ground sloths that weighed about four-tons. The researchers say that the fact that these carnivores and their prey were larger than their contemporary predators and their victims could explain why the cats had more broken teeth.
Larger teeth break more easily than smaller teeth, so carnivores with larger teeth may be likely to break more teeth when attempting to take down large prey.
"The net result of our study is to raise questions about the reigning hypothesis that 'tough times' during the late Pleistocene contributed to the gradual extinction of large carnivores. While we can not determine the exact cause of their demise, it is unlikely that the extinction of these cats was a result of gradually declining prey."
The findings were detailed online in the journal PLOS ONE on December 26.