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.