Why Mammals Are So Good at Hearing (And Chewing)

Why Mammals Are So Good at Hearing (And Chewing)

One hundred and twenty million years ago, when northeastern China was a series of lakes and erupting volcanoes, there lived a tiny mammal just a few inches long. When it died, it was fossilized down to its most minuscule ear bones. A wealth of evidence from fossils and developing embryos suggests that two of these ear bones were once jawbones.