Extinct Ice Age saber-toothed cats and ground wolves had high rates of joint bone disease, according to a recent study published in the open-access journal PLOSONE by Hugo Schmökel of Evedencia Academy in Sweden and colleagues. Osteochondrosis is a developmental bone disease known to affect the joints of vertebrates, including humans and various domesticated species. However, the disease is not well documented in wild species, and published cases are rare.

In the study, Schmökel and colleagues found signs of the disease in fossilized limb bones of Ice Age saber-tooth cats (Smilodonfatalis) and direwolves (Aenocyondirus), which date from about 55,000 to 12,000 years ago.

Photos of the La Brea Tar Pits and ground wolf recovery on display at the museum. Image credits: La Brea Tar Pits and Museum and Los Angeles County Museum of Natural History, CC-BY4.0

La Brea Tar Pits Research Results

Researchers examined more than 1,000 limb bones from saber-toothed cats and more than 500 limb bones from land wolves from the La Brea Tar Pits in the late Pleistocene and found that many of the bones had small defects consistent with a specific bone disease called osteochondrosis (OCD). These defects occur primarily in the shoulder and knee joints, with an incidence of up to 7% in the bones examined, significantly higher than the incidence observed in modern species.

Impact and future research

The study was limited to isolated bones from one fossil site, so further study of other fossil sites may reveal prevalence patterns of the disease and, by extension, aspects of these animals' lives. For example, it's unclear whether these joint problems hinder these predators' ability to hunt. Additionally, OCD is common in highly inbred modern domestic dogs, so it's possible that the high incidence in these fossil animals is a sign of population decline as these ancient species became endangered.

Detail of illustration of a saber-toothed tiger in the La Brea Tar Pits in 1911. Image credit: Robert Bruce Horsford and Los Angeles County Museum of Natural History, CC-BY4.0

Connections to modern animals

The authors add: "This study, made possible by the unparalleled large sample size of the La Brea Tar Pits and Museum, adds to the growing literature on the paleopathology of Smilodon and ground wolves. The collaboration between paleontologists and veterinarians confirms that although these animals were large carnivores that experienced hard times and are now extinct, they shared diseases with the cats and dogs we have in our homes today."

Compiled source: ScitechDaily