Yi (dinosaur)
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Yi qi Temporal range: MIddle or Late Jurassic, 160 Ma |
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| Life restoration | |
| Scientific classification | |
| Kingdom: | Animalia |
| Phylum: | Chordata |
| Class: | Reptilia |
| Clade: | Dinosauria |
| Order: | Saurischia |
| Suborder: | Theropoda |
| Family: | †Scansoriopterygidae |
| Genus: |
†Yi Xu et al., 2015 |
| Species: | †Y. qi |
| Binomial name | |
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Yi qi Xu et al., 2015 |
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Yi is a genus of scansoriopterygid dinosaurs from the Late Jurassic of China. Its only species, Yi qi (Mandarin pronunciation: [î tɕʰǐ]; from Chinese: 翼; pinyin: yì; literally: "wing" and 奇; qí; "strange"), is known from a single fossil specimen of an adult individual found in Middle or Late Jurassic of Hebei, China, approximately 160 million years ago. It was a small, possibly tree-dwelling (arboreal) 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.
Yi qi is known only from a single partial skeleton (holotype specimen STM 31-2) currently in the collections of the Shandong Tianyu Museum of Nature. The fossil was compressed and is visible on a stone plate and a counterplate. It is largely articulated, including the skull, lower jaws, neck and limb bones but lacking most of the backbone, pelvis and tail. Yi was a relatively small animal, estimated to weigh about 380 grams (0.84 lb).
Like other scansoriopterygids, the head was short and blunt-snouted, with a downturned lower jaw. Its few teeth were present only in the tips of the jaws, with the four upper front teeth per side being the largest and slightly forward-pointing, and the front lower teeth being angled even more strongly forward. The long, slender forelimbs were similar, overall, to those of most other paravian dinosaurs. Like other scansoriopterygid dinosaurs, the first finger was shortest and the third was the longest. Unlike all other known dinosaurs, a long, pointed wrist bone known as a "styliform element", exceeding both the third finger and the ulna in length, extended backward from the forelimb bones. This styliform, an adaptation to help support the membrane, may have been a newly evolved wrist bone, or a calcified rod of cartilage. It was slightly curved and tapered at its outer end.
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