Saber-Toothed Cats And Dire Wolves May Have Been Heavily Inbred, New Study Of La Brea Tar Pits Fossils Shows

Saber-toothed cats and dire Wolves are among the most famous apex predators of the Ice Age. But both went extinct about 10,000 years ago.

Now, new research shows saber toothed cats and dire wolves had something unfortunate in common. The two animals appear to have had genetic bone defects possibly due to inbreeding. Smithsonian Magazine says a new study points in that direction.

The La Brea tar pits in Los Angeles are a treasure trove of fossils. The tar pits formed when crude oil seeped to the surface in pools. The lighter part of the oil evaporated, leaving only the thick heavy tar. Prey animals would become stuck in the gluey mess. Predators seeking an easy meal fell victim too. The tar pits are old enough for Ice Age fossils but not old enough to contain dinosaur fossils.

Because clouded leopards can open their jaws wider and have the largest canines in proportion to their bodies they are sometimes called modern saber tooth cats

Saber-toothed cats (Smilodon) were members of an extinct cat-like family called Machairodonts. Machairodonts and Nimravids and modern felines shared a common ancestor. Both of the other families went extinct. There is still debate about how the long and not too sturdy canines were used. Extra long fangs have evolved in cats several times. The only example living today is the clouded leopard (Neofelis nebulosa).

Similarly, dire wolves (Aenocyon dirus) and gray wolves (Canis lupus) are not closely related. They did diverge from a common ancestor about 5 million years ago.

Wolf. Original public domain image
Modern gray wolves are not related to dire wolves, although the appearance is similar. Dire wolves were larger and it is thought the smaller wolves out competed them when very large prey died out, Wolf. Original public domain image by U.S. Forest Service (source) is licensed under CC-CC0 1.0

The tar trapped about 2,000 of the cats and 4,000 of the wolves. A recent study of the fossils showed evidence of inherited disease.

“For some types of bones, between 4 and 6 percent had signs of osteochondrosis dissecans (OCD), a joint condition in which the bone underneath cartilage dies and can break loose due to a lack of blood flow. The high rate of disease could suggest the animals were inbreeding as they went extinct, according to the new paper” Links in original. The report was published in PLOS One. PLOS One is a peer-reviewed open access journal. Although the percentage seems small, researchers said it is very significant. Links in original.

A National Parks Service photo showing the kink in a cougar’s tail. This is a sign of inbreeding.

In breeding is a problem for modern mammals. Freeways and other blockages prevent free movement and lead to inbreeding. Tigers in India and mountain lions in the Santa Monica Mountains show signs of inbreeding. Efforts to create wildlife corridors such as Liberty Canyon are expected to help with the problem.

Published by ursusrising

long time writer and editor living in Los Angeles

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