The study's lead author, Steven Wallace, an associate professor in the department of geosciences and member of the Don Sundquist Center of Excellence in Paleontology at East Tennessee State University, used comparative analysis of saber-toothed cat anatomy to help determine the animal's taxonomy. The analysis was primarily based on structure of the animal's lower jaw and teeth, smaller than the Smilodon and about the size of a modern Florida panther.
"The taxonomy of this animal was controversial because when it was first published 20 years ago, they only had one partial, somewhat-decent lower jaw, and it was missing some of the critical features," Hulbert said. "We now have more complete specimens showing it has a mixture of primitive and advanced characters, and does not match any previously named saber-toothed cat genus or species."
Originally misidentified as a member of the genus Megantereon in the early 1980s, Rhizosmilodon is instead the sister taxon to Megantereon and Smilodon, and the oldest of the group. These three cats are in the same tribe -- meaning they are more closely related than a family or subfamily -- and are often called as saber-toothed cats because of their long canine teeth, Hulbert said.
"When people think of saber-toothed cats, they think of it as just one thing, as if the famous tar pit saber-toothed cat was the only species, when in fact, it was an almost worldwide radiation of cats that lasted over 10 million years and probably had a total of about 20 valid species," Hulbert said. "Counting the newly described animal, there are now six different species of saber-toothed cats known just from Florida."
Saber-toothed cat expert Julie Meachen, an in
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University of Florida