Yi qi
Temporal range: Middle or Late Jurassic
Yi qi
A restoration of Yi qi
Scientific classification
Kingdom: Animalia
Phylum: Chordata
Class: Sauropsida
clade: Dinosauria
Superorder: Theropoda
Order: Saurischia
Family: †Scansoriopterygidae
Genus: Yi
Xu et al., 2015
Species: Y. qi
Binomial name
Yi qi
Xu et al., 2015

Yi qi is the only known species in a genus of scansoriopterygid dinosaurs from the Late Jurassic of China. Yi qi (from Chinese: 翼; pinyin: ; literally: "wing" and 奇; ; "strange") is known from a single fossil specimen of an adult individual found in the Middle or Late Jurassic of Hebei, China, approximately 159 million years ago. It was a small, possibly tree-dwelling animal. Like other scansoriopterygids, Yi possessed an unusual, elongated third finger, that helped to support a membranous gliding plane made of skin. The planes of Yi qi were also supported by a long, bony strut attached to the wrist. This modified wrist bone and membrane-based plane is unique among all known dinosaurs, and might have resulted in wings similar in appearance to those of bats.


The type specimen STM 31-2 is housed in the collections of the Shandong Tianyu Museum of Nature. It was compressed and is visible on a stone plate and a counterplate. The specimen is largely complete with a skull, lower jaws, neck, and limbs bones but lacking most of the backbone, pelvis, and tail. Yi qi was the size of a pigeon, estimated to weigh about 380 grams (0.84 lb).

Characteristic of scansoriopterygids, the head was short and blunt-snouted with a downturned lower jaw, hollow bones, and the first digit was the shortest while the third finger was the longest. It had few teeth, all at the front of the mouth. The forelimbs were slender, indicative of an arboreal lifestyle.

A unique characteristic of this dinosaur was that a long, pointed wrist bone known as a "styliform element" extended backward from the forelimb bones. It may have served as a support structure for Yi's membraned wings. The scansoriopterygid also had simple feathers structurally similar to downy feathers on its body. The head feathers and membrane were light in color due to the detection of phaeomelanosomes in the fossil. Eumelanosomes, organelles producing darker colors, were found in all other scanned locations, especially in the calf feathers.

Discovery and naming[]

Fossil of Yi qi

The only fossil of Yi qi was found by a farmer, Wang Jianrong, in a quarry near Mutoudeng Village. Wang sold the fossil to the Shandong Tianyu Museum of Nature in 2007, where they began further preparation of the fossil. The initial study of Yi was published in the journal Nature on April 29, 2015.

Yi qi as the shortest generic name of any dinosaur, containing two letters. Its binomial name, Yi qi, is also the shortest possible name under articles 11.8.1 and 11.9.1 of the International Code of Zoological Nomenclature.


Yi qi is a member of an extinct family of therapod dinosaurs called Scansoriopterygidae. They were of the clade Paraves which gave rise to modern-day birds.


Yi qi was likely a glider due to the lack of evidence for large pectoral muscles needed to power flight and the cumbersome nature of the styliform.


Yi qi lived in forest habitats dominated by bennettitales, ginkgo trees, conifers, and leptosporangiate ferns. They shared their environments with basal birds such as Anchiornis which outcompeted Yi.


A Model of Yi qi

In popular culture[]


Yi qi/Gallery