Sunday, May 26

Saber-toothed cats and dire wolves carried a terrible disease in their bones

About 50,000 to 10,000 years ago, as the ice sheets melted and the planet warmed, some 100 species of gigantic animals began to disappear without a trace.

Paleontologists have been trying to figure out exactly how these animals died, including such iconic predators as the saber-toothed cat and dire wolf. Some hypotheses suggest strong competition for limited food exacerbated by the arrival of humans and gray wolves. But new evidence suggests that a bone disease that can debilitate modern dogs and cats, and even some of their humans, may also have played a role.

In a published document Wednesday in PLoS One magazine, researchers report that as the climate has changed, the bones of saber-toothed cats and dire wolves have been riddled with defects associated with osteochondrosis dissecans, or OCD, a serious developmental disease in which holes form in the bone caused by the development of tissue that has never hardened. In a live animal, the hole is filled with a flap of cartilage which can lead to painful inflammation. It is commonly referred to as osteochondritis dissecans.

These findings reveal a fossilized snapshot of how the physiologies of top predators of the Pleistocene epoch most likely faltered under environmental pressures, he said. Marine Balisicurator of the Raymond M. Alf Museum of Paleontology in Claremont, California, and author of the article.

OCD is a common orthopedic disease that affects the rapidly growing joints of dogs. While less common among cats, cases have been reported among snow leopardswhich could mean that OCD is underreported in wild animals, said Dr. Hugo Schmökel, a veterinary orthopedic surgeon based in Strömsholm, Sweden, and author of the article.

Dr. Schmökel visited the La Brea Tar Pits in Los Angeles in 2022 to study whether saber-toothed cats and dire wolves suffered from cruciate ligament disease. Instead, something else caught his eye: divots of various sizes that furrow the knee and shoulder joints of these ancient carnivores.

While paleontologists had noted these defects, “no one realized that perhaps it was pre-mortem, not post-mortem bone damage,” said Dr. Schmökel.

With the help of Dr. Balisi, then a postdoctoral fellow at the La Brea Tar Pits, e Aisling Farrella senior collections manager, Dr. Schmökel inspected more than 1,000 saber-toothed cat and dire wolf limb bones.

The team found that around six percent of the limb bones of young adult and juvenile saber-toothed cats, particularly the knee joints, had fissures measuring less than seven millimeters.

Nearly three percent of young adult and juvenile wolves also had knee joint defects that tended to be larger, measuring more than 12 millimeters. Small shoulder joint defects were more common in wolves, as in dogs, totaling nearly five percent. Some adult limbs, but no juvenile limbs, showed signs of osteoarthritis, a degenerative joint disease that can result from OCD.

The prevalence of the disease among animals appeared to be higher than among modern animals and humans, said Dr. Schmökel.

From the bones alone, it’s not clear why OCD hit like that. Nor can the researchers say for sure how it affected the animals’ quality of life or mobility. In modern pets, the disease can cause varying levels of pain and lameness. In the first few years of life, these bone defects can heal on their own; it may not have been much harm, at least to some individuals. The animals’ social behavior may also have mitigated the worst of the disease, he said Larissa DeSantisa Vanderbilt University paleontologist who was not involved in the study.

In an email, he said other specimens from the La Brea Tar Pits had signs of “hip dysplasia and severe arthritis, revealing the ability of these Ice Age predators to live for an extended period of time with such injuries.” .

But for the researchers, the higher prevalence of OCD offers reasons to speculate that there was an inbreeding problem between saber-toothed cats and dire wolves due to dwindling isolated populations. Dr. Schmökel points to modern animals as Royal Isle Wolves AND Florida panthers who have experienced the same.

While Dr. DeSantis is skeptical OCD was implicated solely in the extinction of these apex predators, Dr. Balisi says the findings are a spur for further research.

The signs of the disease, Dr. Balisi said, “could be a morphological manifestation of something deeper that we can’t get to yet, but I think it’s just a matter of time.”