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Fossil range: Early Cretaceous, 122 Ma
Scientific classification









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Xu & Wang, 2003

Yixianosaurus (meaning "Yixian lizard") was a maniraptoran dinosaur genus from the Early Cretaceous (Aptian stage, 122 million years ago) of China. It is known only from a pair of fossilized arms complete with fossilized feathers. Its exact placement within Maniraptora is uncertain, though its hands resemble those of another feathered dinosaur, Epidendrosaurus.[1]

The type species, Yixianosaurus longimanus, was formally described by Xu X. & Wang Xiao-lin in 2003. The partial skeleton was recovered in Liaoning, in northeastern China.[2]


Yixianosaurus is known only from a single specimen, holotype IVPP V12638, which likely derived from the Dawangzhangzi Bed (early Aptian stage, 122 million years ago).[2] It is a compression fossil, viewed from behind and preserved on a single slab has been sawed into several pieces. It consists of the shoulder girdle together with a pair of fossilized arms complete with fossilized feathers and some ribs and gastralia. Yixianosaurus has a very long hand, 140% of the length of the 89 millimetres (3.5 in) long humerus. The second finger is the longest. The fingers bear large and recurved claws. The feathers are not preserved well enough to show a specific structure, but they appear similar to the contour feathers of some Yixian Formation birds.[1] The large hands could have served in catching prey or assisted in climbing. The total body length has been estimated at 1 metre (3.3 ft), the weight at 1 kilogram (2.2 lbs).[3] Xu et al. (2013) suggested that the presence of large pennaceous feathers on parts of the forelimb strongly supports that Yixianosaurus was adapted for limited aerial locomotion.


The describers considered the exact placement of Yixianosaurus within Maniraptora to be uncertain, but because the hand length resembled that of another feathered dinosaur, Epidendrosaurus (now Scansoriopteryx), they suggested it was a close relative of the Scansoriopterygidae. Other researchers have suggested the specimen may have come from a dromaeosaurid. Subsequent analyses were divided on whether is it is more primitive and outside the clade Eumaniraptora &ndahs; this would mean that advanced characteristics such as the long hands and short arms evolved independently in this species[4] – or a basal member of the more advanced Paraves. In a 2017 re-evaluation of the Harlem Archaeopteryx specimen as an anchiornithid called Ostromia, Yixianosaurus is found to be the most basal paravian.[6] However, two other studies published the same year argued that Yixianosaurus was most closely related to Xiaotingia, with both genera being either relatives of scansoriopterygids[7] or anchiornithids.


  1. ^ Yixianosaurus longimanus, a Peculiarly Normal Yixian Theropod
  2. ^ *Xu X. & Wang Xiao-lin. (2003). "A new maniraptoran from the Early Cretaceous Yixian Formation of western Liaoning". Vertebrata PalAsiatica 41(3): 195–202.