Xianglong

Xianglong (meaning "flying dragon" in Chinese) is a genus of Cretaceous lizard discovered in the Zhuanchengzi, near Yizhou, Yixian, Liaoning Province of China. It is known from LPM 000666, a single complete skeleton with skin impressions. The specimen comes from the Barremian-aged (Lower Cretaceous) Yixian Formation, near Yizhou. The most notable feature about Xianglong is its bizarre oversized ribs, eight on each side, which were attached to a membrane of body tissue and allowed the lizard to glide, similar to living gliding Draco lizards. While in its original description it was considered to be an acrodont lizard, with a cladistic analysis in the same study suggesting that it was grouped with iguanians such as agamines, chamaeleonids, and leiolepidines, it was later shown that this was due to misinterpretation of the crushed skull, and its affinities with other lizards remains uncertain.

== Description == thumb|Size of Xianglong (blue, bottom) compared to a human hand, the living gliding lizard [[Draco volans, as well as other unrelated extinct gliding reptiles]] The holotype specimen of Xianglong was long, of which was tail, although the describers say it was probably a juvenile. This is indicated by the unossified carpals and poorly-ossified tarsals. Metacarpal IV is shorter than the other metacarpals, and pedal digit V is greatly elongated. The radius and ulna are distally divergent. The body is covered in small, granular scales, showing little size variation. Xianglong had slightly curved claws, indicating that it was arboreal. The ribs of the animal, that functioned as gliding organs, were found in a half-open position, which indicates a post-mortem relaxation of the folded wing. This is currently the only known fossil gliding lizard, though there are other unrelated animals that also use their ribs to glide.