Extinct squirrel-like creatures from China suggest the earliest mammals originated more than 200 million years ago, much earlier than often previously thought, researchers say.
The fossils were discovered in the last three years by private collectors and amateur paleontologists in a Liaoning province cornfield in northeastern China. Liaoning has become famous for the trove of feathered dinosaurs and winged reptiles known as pterosaurs unearthed there over the last decade. The province is also known for a fossil of a baby dinosaur inside a mammal's gut, the first direct proof that mammals dined on dinosaurs.