Sinosauropteryx, meaning “Chinese reptilian wing,” is a genus of theropod dinosaur from the Late Jurassic to the Early Cretaceous Period 135 to 121 million years ago. It was discovered in 1996 by two Chinese farmers in the dry countryside near Liaoning Province, China. The same area has also produced later on other bird-like dinosaur fossils including Caudipteryx and Protarchaeopteryx.

Three complete skeletons of Sinosauropteryx have been found, including few samples of protofeathers, stomach contents, unlaid eggs, and internal organs. Sinosauropteryx is the earliest bird-like dinosaur discovered.

Sinosauropteryx is the first dinosaur fossil found that showed evidence of having primitive feathers. Unlike modern feathered birds, however, this dinosaur could not fly; feathers were most likely used for insulation, keeping it warm.

It had downy feathers along its back and sides, forming a mane-like tuft on the back of its head. It was about 4 feet long and was bipedal. It stood 11.4 inches tall at the hips and weighed roughly 5.5 pounds. Its longest feathers were about 1.5 inches long, while most measured less than a tenth of an inch.

It had two short forelimbs and many sharp teeth. Like other theropod, it was a meat eater and probably preyed upon small animals and insects. It had a very long tail, the longest of any theropod (relative to its size). The tail was probably used for balance and making quick turns.