Pits offer trove of facts for studying prehistoric cats

An iconic animal of North America’s ice age is the sabertoothed cat, which is often called a saber-toothed tiger, though it’s no more related to a tiger than it is to a lion or a house cat. Its scientific name, Smilodon, derives from meaning tooth (think orthodontics) and a Greek word meaning carving knife — so, the carving-knife tooth cat.

Adult cats were about the size of a modern-day lion, weighing 350 to 550 pounds, but were shaped differently, much more powerful in the front and slimmer in the back. Their front limbs especially were more robust, with thicker bones and much larger knobs for muscle attachment.

Most animals start out with rather weak limbs, and as they mature the bones get thicker and stronger. A recent bit of research reported in the journal PLOS One asked how Smilodon bones changed as they matured, and found an interesting pattern.

Such a question would be very difficult to answer for most prehistoric animals because finding the bones of young animals is usually very rare. What permitted this research was a wonderful site in downtown Los Angeles, the famous Rancho La Brea.

Often referred to as “tar pits,” they contain no tar at all. (Tar is a man-made material formed by distilling coal, wood, petroleum or peat.) The ponds at Rancho La Brea actually contain asphalt, which formed when petroleum seeped up from deep below ground and the volatiles (the lightweight materials) evaporated, leaving the thicker and stickier asphalt behind to trap many an unwary animal during the past 40,000 years.

Remains of animals found there included many large animals such as mammoths, mastodons, three species of ground sloths, camels, bison, horses, deer, and glyptodonts (armadillo-like animals the size and shape of a Volkswagen Beetle), as well as smaller animals including storks, teratorns (large vultures), turkeys, wolves, coyotes, foxes, badgers, skunks, rabbits, rodents, turtles, snails, insects and even microscopic fossils such as pollen grains.

Smilodon is the secondmost-common large animal at Rancho La Brea (after the dire wolf), and thousands of its bones have been recovered, including many from juveniles. Previous research using isotopes showed that it most commonly preyed on bison and camels.

Smilodon is not the only large cat preserved there — so is Panthera atrox, the American lion, which was about the same size as a modern African lion. It made a good control group for comparison with Smilodon even though it wasn’t as common, with only about half as many juvenile bones available for analysis.

So how did the youngsters of these two large cats grow? Panthera grew like modern felines — as a juvenile it had relatively slender bones that got stronger with maturity.

Smilodon kittens grew differently. They followed the same general pattern of change, but even as kittens their bones were much more robust than those of other large cats and just got more so as they approached maturity.

I wonder if they would have made good pets, but perhaps saying “Here kitty kitty kitty” wouldn’t have been such a great idea.