Surgeon aims to diagnose deformities of extinct saber-toothed cats

Robert Klapper has examined scores of damaged and diseased human knees, hips and shoulders. But a visit to the La Brea Tar Pits and Museum introduced the orthopedic surgeon to the suffering of an extinct cat — and a scientific mystery. In 2000, Klapper took a break from his patients at Cedars-Sinai Medical Center in Los Angeles to visit the nearby tar pits, where myriad mammals and other animals (SN: 5/17/14, p. 18) have been getting stuck for the last 40,000 years. (Yes, modern birds and insects still wander in.)

After examining a museum display of broad-snouted dire wolf (Canis dirus) skulls, Klapper made a beeline for the security guard and asked to see a curator. He badgered then collections manager Chris Shaw with questions about why the skulls looked so perfect — no signs of cancers, fractures or arthritis.

“Instead of throwing me out,” Klapper says, Shaw took Klapper into the bowels of the museum and pulled out a drawer of bones from saber-toothed cats (Smilodon fatalis), one of the abundant prehistoric animals preserved in the pits about 14,000 years ago. Klapper noticed a pelvis with a surface that reminded him of a medieval mace: One hip socket was spiky with sharp edges, a telltale sign of arthritis. At the healthy hip socket, the bone was billiard ball smooth.

That kind of bone damage did not happen overnight. The arthritic animal had been disabled for years, Klapper estimated, perhaps even from birth. The surgeon asked a favor: “I’d love to get a CT scan.” Signing out the ancient cat’s pelvis, he says, was a thrill.

Paleontologists have long debated whether saber-toothed cats were solitary or social hunters. If this lame cat had been unable to hunt for years, which is what its traumatized hip bone indicated to Klapper, it could have survived only with help from other cats.

Klapper scanned that fossilized cat pelvis but left the images untouched for years, occupied with his hospital job and hosting ESPN Radio’s Weekend Warrior, a health and sports program. Now, collaborating with Emily Lindsey, a paleoecologist at La Brea, Klapper plans to use more sophisticated radiology techniques to diagnose the deformity and possibly deduce clues about the cat’s lifestyle.

It’s still early days for the revitalized project, Lindsey cautions, but “I’m really excited about it.” The museum houses some 2,000 fossils of saber-toothed cats, several of which the two plan to scan in the months ahead.