Spines of Saber-Toothed Cats Reveal Extinction Clues

Fossils of saber-toothed cats (Smilodon fatalis) recovered from California's La Brea Tar Pits reveal a remarkably high frequency of spinal maladies, including rare spinal nerve tumors dating back to 12,000 and 13,000 years ago. Researchers led by veterinary surgeon Hugo Schmökel analyzed over 3,000 vertebrae, discovering that three individual cats exhibited cavernous hollows in their lower back vertebrae caused by tumors, at a rate roughly 1,000 times higher than modern humans and dogs. The researchers hypothesize that these spinal tumors and deformities were driven by severe inbreeding during the declining twilight years of the species as populations shrank and became increasingly isolated before total extinction at the end of the Pleistocene Epoch. This study provides critical biological insight into the mechanisms of prehistoric extinction, suggesting that shrinking population sizes and reduced genetic diversity manifest as physical deformities that further compromise an endangered species' ability to survive.