Spinal Deformities in Saber-Toothed Cat Fossils Reveal How the Now-Extinct Felines May Have Spent Their Final Days

Researchers studied saber-toothed cat vertebrae found in the La Brea Tar Pits in Los Angeles. They identified a surprisingly high number of deformations, including signs of spinal nerve tumors, hinting at a dwindling population suffering the consequences of inbreeding

Margherita Bassi | Daily Correspondent

August 10, 2026 11:36 a.m.

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Thousands of years ago, sticky tar pits in modern-day Los Angeles, California, became the graveyard for prehistoric felines struggling with deformities and disease. Soon after, the creatures would disappear for good.

Fossilized spines of saber-toothed cats that fell into the La Brea Tar Pits long ago contain signs tumors and other deformities, researchers reported in a study published July 26 in the journal Frontiers in Veterinary Science. The findings suggest that inbreeding occurred as the now-extinct feline’s population declined and offer evidence of how the iconic Ice Age predator spent its final days.

Saber-toothed cats of the species Smilodon fatalis roamed what is now the Americas around 11,000 to 700,000 to years ago. They were top predators during their time, probably feasting on camels, deer and tapirs.

The felines were also competing with fellow carnivores like dire wolves, the prehistoric canines made famous by the “de-extinction” company Colossal Biosciences’ attempt to resurrect them. In fact, study co-author and veterinary surgeon Hugo Schmökel had originally traveled to the La Brea Tar Pits and Museum to investigate joint diseases in dire wolves, reports Science News’ Jake Buehler.

But then he spotted signs of disease in the vertebrae of the large cats. “As a spine surgeon for dogs and cats, I was immediately interested and went back twice to La Brea,” Schmökel, of IVC Evidensia Veterinary Academy in Sweden, tells the outlet.

So, Schmökel and colleagues examined 3,722 vertebrae from at least 849 saber-toothed cats housed at the museum. They’re one of the most common large mammals found in the gooey, bubbling asphalt there, second to dire wolves.  

CT scans revealed a significant number of developmental abnormalities in the feline spines. The team identified 32 vertebrae with arches that hadn’t completely developed, 48 “block” vertebrae where bones had fused together and 226 “transitional” vertebrae that hadn’t formed correctly.

Perhaps most notably, three vertebrae from different individuals contained enlarged holes that allowed nerves and blood vessels to thread through them. The holes’ sizes and smooth remodeled surfaces hint that the cats had spinal nerve tumors.

These tumors are exceedingly rare in modern-day animals, including humans. In our species, for example, they occur because of certain genetic mutations, and doctors usually diagnose up to 0.38 cases for every 100,000 individuals. The study’s results suggest a much greater prevalence among saber-toothed cats at La Brea. They may have had a prevalence of 353 spinal nerve tumors for every 100,000 individuals, the researchers estimate.

The species likely suffered from these deformities because of inbreeding, which allowed harmful DNA mutations to show up more often, although a genetic analysis is needed to prove this. But the thought is that a shrinking population made negative genetic variants more prevalent in the gene pool and thus more likely to be inherited by offspring. In fact, researchers have observed the same spinal malformations in inbred gray wolf populations today.

“Fossil evidence of inherited disorders is uncommon,” Federico Agnolín, a paleontologist at the Argentine Museum of Natural Science who did not participate in the study, tells Science’s Taylor Mitchell Brown. “Documenting a possible increase in developmental abnormalities and rare tumors offers a new perspective on the biological consequences of population decline before extinction.”

Spinal nerve tumors, which were probably painful and could have led to loss of limb function, may have made affected saber-toothed cats more likely to die in the tar pits. They might have been lured by prey stuck in the sticky stuff—and then fell in themselves.

“A trapped prey animal is very attractive for a predator in pain,” Schmökel says in a statement. “A wounded or sick predator must rely on carcasses for surviving, so they’ll take bigger risks to get to them.”

So, what finally made these felines go extinct? Researchers aren’t sure, but a changing climate, human activity and competition with gray wolves may have contributed to their demise.

What’s more, the study reveals what could happen to animals facing similar population pressures today. Twenty species of wild cats are currently classified as endangered or critically endangered by the International Union for Conservation of Nature, which creates global guidance about organisms at risk of extinction.

“Loss of habitat, pollution, hunting or poaching, and in some areas today, climate change, are the cause of the fall in numbers of wild cats,” Schmökel says in the statement. “We can assume that the same happened to Smilodon at the end” of the last Ice Age.

Margherita Bassi is a freelance journalist and trilingual storyteller. Her work has appeared in publications including BBC Travel, Discover magazine, Live Science, Atlas Obscura and Hidden Compass.