Newly identified giant saber-toothed cat roamed North America 5-9 million years ago

A giant saber-toothed cat lived in North America between 5 million and 9 million years ago, weighing up to 900 pounds and hunting prey that likely weighed 1,000 to 2,000 pounds, scientists reported today in a new study.

The researchers performed a careful comparison of seven uncategorized fossil specimens with previously identified fossil and bone samples from around the world to describe the new species. Their discovery argues for the use of the elbow portion of the humerus – in addition to the teeth – to identify fossils of large saber-toothed cats whose massive forearms allowed them to overpower their prey.

The newly identified cat averaged around 600 pounds and could have successfully killed prey weighing up to 6,000 pounds, scientists believe, suggesting their findings provide evidence for another giant cat, one of the largest in the world. history of the Earth.

“We believe these were animals that routinely slaughtered bison-sized animals,” said study co-author Jonathan Calede, assistant professor of evolution, ecology and organic biology. at the Marion campus of Ohio State University. “It was by far the largest living cat at the time.”

Calede completed the study with John Orcutt, assistant professor of biology at Gonzaga University, who initiated the project. Orcutt found a large specimen of arm bone that had been tagged as a cat in the collection of the University of Oregon’s Natural and Cultural History Museum when he was a graduate student, and collaborated with Calede on the effort of several years to determine what type of cat it might be.

They determined that the new species is an ancient relative of the best-known saber-toothed cat Smilodon, the famous fossil found in the La Brea tar pits in California that went extinct about 10,000 years ago.

The Oregon specimen was excavated on the traditional lands of the Cayuse, a tribe attached to the Umatilla and Walla Walla in the Confederate tribes of the Umatilla Indian Reservation. In recognition of its origin, Calede and Orcutt collaborated with the Tamástslikt Cultural Institute to name the new species Machairodus lahayishupup. Machairodus is a genus of large saber-toothed cats that lived in Africa, Eurasia and North America, and in the Old Cayuse language, Laháyis Húpup means “ancient wild cat”.

The study is published today (May 3, 2021) in the Journal of mammalian evolution.

Orcutt and Calede found fossil specimens of similar uncategorized arms at the Idaho Museum of Natural History, where a large cat forearm was accompanied by teeth – generally considered the gold standard for identifying new species. – as well as at the University of California Museum of Paleontology and Texas Memorial Museum.

“One of the big stories about all of this is that we ended up finding specimen after specimen of this giant cat in museums across western North America,” Orcutt said. “They were clearly big cats. We started with some assumptions based on how old they were, between 5 1/2 and 9 million years old, and how tall they were, because those things were huge.

“What we didn’t have then, what we have now, is the test to see if the size and anatomy of these bones tells us anything – and it turns out, yes, they do.”

The largest of the seven Machairodus lahayishupup humerus fossils available for analysis was over 18 inches long and 1.7 inches in diameter. In comparison, the humerus of an average modern adult male lion is approximately 13 inches long.

The researchers hypothesized that if an isolated forearm bone was useful in distinguishing between species, it would be true among the big cat species living today. Calede and Orcutt have visited numerous museums in the United States, Canada and France to photograph forearm specimens of lions, pumas, panthers, jaguars and tigers, as well as fossils of previously identified big cats.

Calede used software to place landmarks on each scanned sample that, when put together, would create a pattern of each bend.

“We found that we could quantify the differences on a pretty fine scale,” Calede said. “It told us that we could use the shape of the elbow to distinguish modern big cat species.

“Then we took the tool from the fossil record – those giant elbows scattered around museums all had one characteristic in common. This told us that they all belonged to the same species. Their unique shape and size told us that they were also very different from anything that is already known. In other words, these bones belong to a species and that species is a new species. “

The researchers calculated body size estimates for the new species based on the association between humerus size and body mass in modern big cats, and speculated on the cat’s prey based on its size. and animals known to have lived in the area during this time: rhinos were particularly abundant, as were giant camels and giant sloths.

Teeth from the Idaho Museum of Natural History were from the lower jaw and did not include the saber-shaped canines, but provided further evidence that the fossil belonged to the genus Machairodus, which gave its machairodontins name – the technical name for a saber-toothed cat, Orcutt said.

“We are pretty convinced that it is a saber-toothed cat and we are convinced that it is a new species of the genus Machairodus,” he said. “Part of the problem is because we haven’t necessarily had a clear picture in the past of how many species are present, our understanding of the relationship between all of these saber-toothed cats is a bit hazy, especially early. their evolution. “

Establishing that the humerus alone can be analyzed to identify a fossil cat has important implications for the field – the “big and beefy” forearm bones of saber-toothed cats are the most common fossil cat specimens. found in the excavations, he said.

Only a reconstruction of the evolutionary history of the saber-toothed cats can determine the place of this new species, but Orcutt and Calede believe that Machairodus lahayishupup existed early in the group’s evolution.

The discovery that this giant cat in North America existed at the same time that similar animals lived in the world also raises another evolutionary question, Calede said.

“We know there were giant cats in Europe, Asia and Africa, and now we have our own giant saber-toothed cat in North America during that time as well,” he said. “There is a very interesting pattern of independent evolution repeated across all continents of this giant body size in what remains a pretty hyperspecialized way of hunting, where we have this giant saber-toothed ancestral cat that has dispersed. on all these continents.

“This is an interesting paleontological question.”

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