Sabertooth skull offers new clues about the extinct mammal

The groundbreaking discovery of a sabertooth cat skull in southwest Iowa has provided the first concrete evidence that this prehistoric predator once roamed the state. The remarkably well-preserved skull, found in Page County, offers rare insights into the life of the iconic Ice Age species before it vanished from Earth around 12-13,000 years ago.

According to Matthew Hill, an associate professor of archaeology at Iowa State and an expert on animal bones, finding any fossilized remains of a sabertooth cat is already a rare occurrence. “The skull is a really big deal,” said Hill. “Finds of this animal are widely scattered and usually represented by an isolated tooth or bone. This skull from the East Nishnabotna River is in near perfect condition. It’s exquisite.”

Hill collaborated with Professor David Easterla of Northwest Missouri State University, to analyze the specimen. Their research has recently been published in the journal Quaternary Science Reviews. 

Using radiocarbon dating, the researchers determined that the cat lived and died at the end of the Ice Age, between 13,605 and 13,460 years ago. Hill believes it may have been one of the last sabertooth cats on the planet, as glaciers receded and temperatures rose.

During this period, southwest Iowa was thought to resemble a parkland with patches of trees interspersed with grassy openings, similar to central Canada today. 

“The cat would have lived alongside other extinct animals like dire wolf, giant short-faced bear, long-nosed peccary, flat-headed peccary, stag-moose, muskox, and giant ground sloth, and maybe a few bison and mammoth,” said Hill.

The researchers theorize that the skull belonged to a subadult (2-3 year old) male at the time of its death. The gaps between the skull’s bony plates indicate that its head was still growing, and its permanent teeth show little wear from cutting and chewing. To determine its sex, they compared the skull measurements with adult male and female sabertooth skulls from the Rancho La Brea tar pits in Los Angeles.

According to Hill, sabertooths were sexually dimorphic, meaning males were larger than females. Since the Iowa skull is larger than many male skulls from the tar pits, the researchers argue it belonged to a male. The experts estimate that the Iowa cat weighed about 550 pounds at the time of its death and might have reached 650 pounds as an adult in prime physical condition. This is considerably larger than the average adult male African lion, which weighs around 400 pounds.

The cause of the sabertooth cat’s death remains unclear, but a broken canine could offer a clue. Hill and Easterla speculate that the animal sustained a severe injury while attacking prey, which ultimately proved fatal within days of the trauma. Small patches of worn-down bone on top of the skull suggest that it slid along a river-bottom before coming to rest and becoming buried for thousands of years.

Fossils like this hold valuable information about the ecology of these extinct animals, their responses to dramatic climate change, and their interactions with new predators and competitors on the landscape, including humans. “Iowa is a fantastic laboratory to do research on extinct Ice Age animals and the people who were just beginning to share the landscape with them,” said Hill.

This recent discovery has opened up new avenues of research beyond the initial analysis. One of the questions researchers are now asking is what the cat’s primary prey might have been during the Ice Age.

Hill suspects that Jefferson’s giant ground sloth, a common species in Iowa at the time, was the cat’s main source of food. These massive creatures, measuring 8-to-10 feet tall and weighing over 2,200 pounds, would sit beside trees and bushes, pulling in leaves and buds to eat. Hill believes that only a large predator with “absolutely lethal jaws and claws” and legs designed for pouncing could have hunted these formidable animals regularly.

To test this hypothesis, Hill is collaborating with his Iowa State colleague, Andrew Somerville, an assistant professor of archaeology and an expert in dietary reconstruction using bone geochemistry. The duo is developing a stable isotope mixing model with samples from the sabertooth cat, other carnivores, and herbivores, such as Jefferson’s ground sloth, muskox, and stag-moose.

“You are what you eat, and it’s locked in your bones,” said Professor Hill. Stable isotopes allow researchers to determine what plants herbivores consumed and, in turn, what herbivores the carnivores ate. This information can be used to piece together local food webs and understand how different species filled ecological niches in their environment.

“So, maybe the sabertooth was primarily eating giant ground sloth, dire wolves primarily moose, and short-faced bears a little bit of everything. Andrew and I are going to figure it out,” said Hill. The research being undertaken by Hill and Somerville promises to shed further light on the lives and habits of these prehistoric predators and the ecosystems they inhabited.

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