An important fossil discovery: Liaoconodon hui, a Mesozoic mammal with a transitional middle ear.

In the clip above, Jin Meng, curator of fossil mammals at the American Museum of Natural History, describes how the well-preserved fossil of Liaoconodon hui, a mammal that lived in the Mesozoic era -- the age of dinosaurs -- shows the development of middle ear structure that characterizes later mammals, including ourselves.