Scansoriopteryx ("climbing wing") is a genus of maniraptoran dinosaur. Described from only a single juvenile fossil specimen found in Liaoning, China, Scansoriopteryx is a sparrow-sized animal that shows adaptations in the foot indicating an arboreal (tree-dwelling) lifestyle. It possessed an unusual, elongated third finger which may have supported a membranous wing, much like the related Yi qi. The type specimen of Scansoriopteryx also contains the fossilized impression of feathers.[1]
Most researchers regard this genus as a synonym of Epidendrosaurus, with some preferring to treat Scansoriopteryx as the junior synonym,[2][3] though it was the first name to be validly published.[4]
The provenance of the Scansoriopteryx type specimen is uncertain, as it was obtained from private fossil dealers who did not record exact geologic data. Czerkas and Yuan initially reported that it had likely come from the Yixian Formation, though Wang et al. (2006), in their study of the age of the Daohugou Beds, suggested that it probably hails from the same beds, and thus is likely a synonym of Epidendrosaurus. The Daohugou Beds supposedly date to the mid-late Jurassic Period,[5] but this is hotly contested. See the Daohugou Beds article for details.
The type specimen of Scansoriopteryx (type genus of the Scansoriopterygidae) and its arboreal adaptations were first presented in 2000 during the Florida Symposium on Dinosaur/Bird Evolution, at the Graves Museum of Archaeology & Natural History, though the specimen would not be formally described and named until 2002.[1]
The type specimen of Scansoriopteryx heilmanni (specimen number CAGS02-IG-gausa-1/DM 607) represents the fossilized remains of a hatchling maniraptoran dinosaur, similar in some ways to Archaeopteryx. A second specimen, the holotype of Epidendrosaurus ninchengensis (IVPP V12653), also shows features indicating it was a juvenile. The specimen is partially disarticulated, and most bones are preserved as impressions in the rock slab, rather than three-dimensional structures.[6] Because the only known specimens are juvenile, the size of a full-grown Scansoriopteryx is unknown–the type specimen is a tiny, sparrow-sized creature.[6] Gregroy S. Paul estimated its size at 50 cm (1.6 ft) in length and 250 g (8.8 oz) in body mass.[7]
Scansoriopteryx is also notable for its wide, rounded jaws. The lower jaw contained at least twelve teeth, larger in the front of the jaws than in the back. The lower jaw bones may have been fused together, a feature otherwise known only in the oviraptorosaurs.