Yi

What it was like

Yi was a tiny, likely tree-climbing dinosaur with an odd kind of wing found in no other known dinosaur. A long, rod-like bone extended from each wrist, and skin stretched between this rod and the arm and fingers to form a bat-like membrane rather than a feathered wing.

Alongside these membrane wings, Yi also had some feathers on its body, but scientists think it likely glided between branches instead of flying under its own power.

Its world

Yi lived from about 165 to 155 million years ago, spanning the Middle and Late Jurassic, in what is now China. Its fossils come from the Tiaojishan Formation.

It shared this forested world with other small, feathered maniraptorans, including Anchiornis, Epidexipteryx, Caihong, Pedopenna, Eosinopteryx, and Serikornis, as well as the plant eater Tianyulong.

How it was found

Xu and colleagues named Yi qi in 2015, from a single fossil skeleton, the only one known. Its strange wrist bone and wing membrane were unlike anything seen before in a dinosaur, and briefly made it one of the most talked-about fossil finds of its year.