The Caudipteryx (“tail feather”) was a 3-foot-(1-meter-) tall, feathered theropod dinosaur that may be the closest-known ancestor of birds to date. Fossils of this creature have been uncovered in the sediment of an ancient lake bed in China’s Liaoning Province. This dinosaur lived during the Late Jurassic to Early Cretaceous periods (about 120 to 136 million years ago) and had asymmetrical feathers, indicating that it did not fly, but used the feathers for insulation. Unlike other theropod dinosaurs, the Caudipteryx did not have a long tail, but it did support feathers up to 8 inches (20 centimeters) in length.