Fossils Used To Classify New Species Of Saber-Toothed Cat
March 15, 2013

New Genus Of Saber-toothed Cat Was Native To Florida

redOrbit Staff & Wire Reports - Your Universe Online

The discovery of five-million-year-old fossils has resulted in the discovery of a new genus and species of extinct saber-toothed cat, according to research published in Wednesday´s edition of the peer-reviewed, open-access journal PLOS One.

The fossils are part of the same lineage as the Smilodon fatalis, a carnivorous apex predator that could have weighed as much as 600 pounds and had long upper canine teeth, according to the study authors. Previous research had suggested that the Smilodon fatalis and its saber-toothed siblings had migrated to North America from elsewhere, but these latest fossils indicate that the new creatures, Rhizosmilodon fiteae, actually originated on this continent.

“Smilodon first shows up on the fossil record around 2.5 million years ago, but there haven´t been a lot of good intermediate forms for understanding where it came from,” study co-author Richard Hulbert Jr., vertebrate paleontology collections manager at the Florida Museum of Natural History on the UF campus, said Thursday in a statement.

“The new species shows that the most famous saber-toothed cat, Smilodon, had a New World origin and it and its ancestors lived in the southeastern US for at least five million years before their extinction about 11,000 years ago,” he added. “Compared to what we knew about these earlier saber-toothed cats 20 or 30 years ago, we now have a much better understanding of this group.”

Rhizosmilodon fiteae was native to the area around what is now Polk County, Florida, Hulbert and his colleagues explained. The fossils used to describe it were uncovered in 1990 during excavations from a phosphate mine. The genus name, Rhizosmilodon, means “root of Smilodon” and suggests that the new animal could be a direct ancestor of the saber-tooth cats that died out 11,000 years ago.

The species was named in honor of Barbara Fite, who two years ago donated one of the specimens that was used in the descriptions of the new creature. The lower jaw portion she donated to the project contained nearly flawless examples of all three chewing teeth, making it vital to the project, according to Hulbert. Comparative analysis of the anatomy of the saber-toothed cat, conducted by Dr. Steven Wallace of East Tennessee State University, was used to help determine the new creature´s taxonomy.

“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.”

During the 1980s, Rhizosmilodon was mistakenly identified as a member of the genus Megantereon, an ancient type of saber-toothed cat that some believe could be an ancestor to Smilodon. The new genus will instead be treated as a “sister taxon” to both Megantereon and Smilodon, and all three cats are said to be in the same tribe, the researchers explained. Rhizosmilodon is believed to be the oldest of the three.

“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.”

“I think that this revision was well-needed,” added Julie Meachen of the Marshall University School of Medicine. “The fact that it´s one of the oldest lineages is really interesting because that means that this exciting group of saber-toothed cats really is a North American tribe — it evolved and persisted in North America.”