When did birds first appear on Earth?

According to a 2013 Discovery News article, researchers at Italy's Museo Geologico Giovanni Capellini analyzed a bird fossil that existed in China 160 million years ago. The dinosaur, named Aurornis xui, is thought to have been a small feathered animal with teeth, claws and a long tail.

The bird's remains were found in the Tiaojishan Formation of the Liaoning Province in northeastern China, and it is believed to have been a ground bird. The name Aurornis comes from the Latin word "aurora" for "daybreak" the Greek word "ornis" for "bird," and xiu is honor of Chinese paleontologist Xu Xing. Before this discovery was made, the earliest bird was believed to have existed 50 to 60 million years ago.