Yi is a genus of gliding scansoriopterygid dinosaurs . Its only species , Yi qi ( from Chinese : 奇 翼 ; pinyin : qí yì ; literally : " strange wing "), is known from a single fossil specimen of an adult individual found in late Jurassic period rocks in Hebei , China . It was a small , tree - dwelling ( arboreal ) animal . Like other scansoriopterygids , it possessed an unusual , elongated third finger , that helped to support a membranous wing made of skin . The wings of Yi qi were also supported by a long , bony strut attached to the wrist . This modified wrist bone and membrane - based wing is unique among all known dinosaurs , and made the wings of Yi qi similar in appearance to those of bats . Descriptionqi is known only from a single partial skeleton ( STM 31 - 2 ) currently in the collections of the Shandong Tianyu Museum of Nature . It 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 upper front teeth being the largest and slightly forward - pointing , and the front lower teeth were angled even more strongly forward . The long , slender forelimbs were similar , overall , to 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 the ulna in length , extended backward from the forelimb bones . This styliform , an adaptation to help support the wing membrane , may have been a newly evolved wrist bone , or a calcified rod of cartilage . The only known specimen of Yi qi preserved a heavy covering of feathers . Unusually based on its classification as an advanced theropod in the clade Pennaraptora ( a group containing theropods with advanced , bird - like feathers ) , the feathers were all very simple in structure and " paintbrush - like ", with long quill - like bases topped by sprays of thinner filaments . The feathers covered most of the body , starting near the tip of the snout . The head and neck feathers were long and formed a thick coat , and the body feathers were even longer and denser , making it difficult for scientists to study their detailed structure . Small patches of skin were also preserved between the fingers and the styliform bone , indicating that unlike all other known winged dinosaurs , the wings of Yi qi were formed by a skin membrane rather than flight feathers . The membrane stretched between the shorter fingers , the elongated third finger , the styliform bone , and possibly connected to the torso , though the inner part of the wing membrane was not preserved in the only known fossil . This would have given the wings a similar appearance to those of modern bats , in an example of convergent evolution . However , in bats , the wing membrane stretches between the fingers , not a styliform wrist bone . Styliform bones are also found in the wings of some modern gliding animals like flying squirrels , the Greater glider , and the prehistoric gliding rodent Eomys quercyi . PaleobiologyThe strange membranous wings of Yi qi are unique among dinosaurs and difficult to interpret . The presence of a long styliform bone adding support to the membrane , found only in other animals that glide , suggests that Yi qi was specialized for gliding flight . While it is possible that some form of flapping flight was also used by this animal , the lack of evidence for large pectoral muscles , and the cumbersome nature of the styliform , make it more likely that Yi qi was an exclusive glider . At best , the researchers who conducted the initial study of the only known Yi specimen concluded that its mode of flight should be considered uncertain . Yi qi , and presumably other scansoriopterygids , possessed a type of wing unknown among any other prehistoric bird relatives . Unlike other paravian dinosaurs , they seem to have replaced bird - like feathers with membranous wings , in what may have been one of many independent evolutionary experiments with flight close to the origin of birds . PaleoecologyThe only known Yi qi fossil was found in rocks assigned to the Tiaojishan Formation , dating to the Callovian - Oxfordian age of the Middle - Late Jurassic , dated to between 165 and 153 million years ago . This is the same formation ( and around the same age ) as the other known scansoriopterygids Epidexipteryx and Scansoriopteryx . The ecosystem preserved in the Tiaojishan Formation is a forest dominated by bennettitales , ginkgo trees , conifers , and leptosporangiate ferns . These forests surrounded large lakes in the shadow of active volcanoes , ash from which was responsible for the remarkable preservation of many of the fossils . Based on the Tiajishan ' s plant life , its climate would have been subtropical to temperate , warm and humid . Other vertebrate fossils found in the same rock quarry as Yi qi , which would have been close contemporaries , included salamanders like Chunerpeton tianyiensis , the flying pterosaurs Changchengopterus pani , Dendrorhynchoides mutoudengensis , and Qinglongopterus guoi , as well as the early tree - dwelling mammal species Arboroharamiya jenkinsi . HistoryThe first and only known fossil specimen of Yi qi was found by a farmer , Wang Jianrong , in a quarry near Mutoudeng Village ( Qinglong County , Hebei ) . Wang sold the fossil to the Shandong Tianyu Museum of Nature in 2007 , at which point Ding Xiaoqing , a technician at the museum , began further preparation of the fossil . Because many of the unique features and soft tissues of the specimen were uncovered by museum staff during preparation rather than amateur fossil sellers , the scientists who studied it were confident that it was authentic and unaltered . The initial study of Yi was published in the journal Nature and appeared on the Internet 29 April 2015 . The team of scientists who authored this initial study were led by Xu Xing and also included Zheng Xiaoting , Corwin Sullivan , Wang Xiaoli , Xing Lida , Wang Yan , Zhang Xiaomei , Jingmai O ’ Connor , Zheng Fucheng Zhang , and Pan Yanhong .