Scansoriopterygid
| Scansoriopterygids Temporal range: Middle to Late Jurassic, 165–156 Ma |
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| Fossil specimen of Epidexipteryx hui | |
| Scientific classification | |
| Kingdom: | Animalia |
| Phylum: | Chordata |
| Class: | Reptilia |
| Clade: | Dinosauria |
| Order: | Saurischia |
| Suborder: | Theropoda |
| Clade: | Paraves |
| Family: |
†Scansoriopterygidae Czerkas & Yuan, 2002 |
| Type species | |
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Scansoriopteryx heilmanni Czerkas & Yuan, 2002 |
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| Species | |
Scansoriopterygidae (meaning "climbing wings") is an extinct family of climbing and gliding maniraptoran dinosaurs. Scansoriopterygids are known from four well-preserved fossils, representing three species, unearthed in the Tiaojishan Formation fossil beds (dating to the mid-late Jurassic Period) of Liaoning and Hebei, China.
Scansoriopteryx heilmanni (and its likely synonym Epidendrosaurus ninchengensis) was the first non-avian dinosaur found that had clear adaptations to an arboreal or semi-arboreal lifestyle–it is likely that they spent much of their time in trees. Both specimens showed features indicating they were juveniles, which made it difficult to determine their exact relationship to other non-avian dinosaurs and birds. It was not until the description of Epidexipteryx hui in 2008 that an adult specimen was known. In 2015, the discovery of another, larger adult specimen belonging to the species Yi qi showed that scansoriopterygids were not only climbers but also had adaptations that could have been used for gliding flight.
Scansoriopterygids are among the smallest dinosaurs known. The juvenile specimens of Scansoriopteryx are the size of house sparrows, about 16 centimeters long, while the adult type specimen of Epidexipteryx is about the size of a pigeon, about 25 centimeters long (not including the tail feathers).
Scansoriopterygids differentiate from other theropod dinosaurs in part by their extremely long third fingers, which were longer than the first and second digits of the hand. In all other known theropods, the second finger is the longest. At least one species, Yi qi, also had a long "styliform" bone growing from the wrist, which, along with the third finger, helped support a bat-like wing membrane used for gliding. This use of a long finger to support a wing membrane is only superficially similar to the wing arrangement in pterosaurs.
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