What killed saber-toothed cats? New study points to diseased bones

Despite being extinct large predators, a new study shows they shared common illnesses — potentially contributing to their fall — with the cats and dogs in our homes today.
Sade Agard
Defected joint in an adult saber-toothed cat/ An extinct species (smilodon) of the saber-toothed cat
Defected joint in an adult saber-toothed cat/ An extinct species (smilodon) of the saber-toothed cat

Schmökel et al/ La Brea Tar Pits and Museum & Natural History Museum of Los Angeles County  

Ice Age saber-toothed cats and dire wolves had a high prevalence of bone disease in their joints, found a study published in PLOS ONE on July 12. 

The findings help to illuminate their health and how this potentially impacted hunting. The high occurrence of OCD also suggests a possible link to declining populations as these species approached extinction.

Poor health and saber-toothed cats' extinction

Dr. Hugo Schmökel, the chief veterinary officer at Evidensia Academy, Sweden, and colleagues examined fossil limb bones from the Late Pleistocene — approximately 55,000 to 12,000 years ago.

The fossils originated from the renowned La Brea Tar Pits, an urban paleontological research site in Los Angeles famed for its remarkably comprehensive preservation of diverse ancient plants and animals.

The researchers identified signs of osteochondrosis dissecans (OCD), a specific manifestation of bone disease, in both species. OCD is known to affect the joints of vertebrates, including humans and various domesticated species. However, documentation in wild species is rare.

The study focused on over 1,000 limb bones of saber-tooth cats ((Smilodon fatalis) and over 500 limb bones of dire wolves (Aenocyon dirus), finding small defects consistent with OCD in many bones. 

The incidence of the disease was notably high, reaching up to 7 percent of the examined bones, which is significantly higher than observed in modern species. The affected joints were primarily the shoulders and knees.

What killed saber-toothed cats? New study points to diseased bones
Large subchondral defects in adult saber-toothed cat (S.fatalis)

While the study's findings are limited to isolated bones from a single fossil site, further investigations on other fossil locations could unveil patterns in the prevalence of the disease. This would help to consolidate our understanding of these ancient animals' lives.

It remains uncertain whether the joint problems would have affected the hunting abilities of these predators. Moreover, the high incidence of OCD in these ancient species may suggest declining populations as they neared extinction. 

The disease is commonly observed in highly inbred domestic dogs. The researchers speculate that the prevalence of OCD in the fossils might indicate a similar genetic vulnerability due to reduced population sizes.

"This study adds to the growing literature on Smilodon and dire wolf paleopathology, made possible by the unparalleled large sample sizes at the La Brea Tar Pits & Museum," said the authors in a press statement.

"This collaboration between paleontologists and veterinarians confirms that these animals, though they were large predators that lived through tough times and are now extinct, shared common ailments with the cats and dogs in our very homes today."

The research opens avenues for further exploration of the health and well-being of ancient species.