"I started noticing this trend," she said.
Long before cats came to be, the earth was home to a number of toothy carnivores that don't exist today. Nimravids were meat eaters that roamed the world for nearly 35 million years, from about 42 to 7 million years ago, alongside another group of extinct predators called the Barbourofelids, which lived for 20 million years until they, too, died out.
"If you saw one of these animals you'd probably think it was a cat, but true cats didn't evolve until millions of years later," Meachen said.
These animals left no living descendants, but thanks to fossilized bones we know their upper canines came in a wide range of shapes and sizes. Some species had canines that were shorter and round in cross section; others were longer, flattened side-to-side, and more oval in cross section. Some were even serrated "like a steak knife," Meachen said.
To find out if sabertooth predators with longer, thinner teeth and more delicate dentition generally had thicker forelimbs, Meachen measured the fossilized arm bones and upper canines of hundreds of museum specimens of extinct cats, nimravids and barbourofelids that once roamed North America.
She also measured the teeth and arm bones of 13 cat species living today such as the tiger and the clouded leopard all of which have conical teeth.
When she compared the dimensions of the teeth to those of the arms, she found that each group of animals gradually converged on the same solution the longer the teeth, the thicker the forelimbs. The results held up even after taking into account the fact that bigger species generally have bigger bones.
She attributes the striking similarities among the species to convergent evolution "The same correlated sets of traits arose repeatedly through time," Meachen said.
"This means that sabertooth cats weren't actually that special in the big scheme of things,"
|Contact: Robin Ann Smith|
National Evolutionary Synthesis Center (NESCent)