Xianglong

Xianglong (meaning "flying lizard" in Chinese) is a genus of Cretaceous lizard discovered in the Liaoning Province of China.[1] It is known from LPM 000666, a single complete skeleton with skin impressions. The specimen comes from the Barremian-age 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. It was an acrodont lizard, and a cladistic analysis indicates it was grouped with iguanians such as agamines, chamaeleonids, and leiolepidines.[2]

The fossil specimen found was 15.5 centimetres (6.1 in) long, 9.5 centimetres (3.7 in) of which was tail, but the describers say it was a juvenile. So far this is the only known fossil gliding lizard, though there are other unrelated animals that also use their ribs to glide.

Gliding ability
Xianglong is one of the few creatures that glide using their ribs. Other creatures, such as the flying squirrel and the Malabar Flying Frog, Rhacophorus malabaricus, have a different membrane attachment, toes to toes or limb to limb. Two creatures use the same way to glide, the present day Flying Lizard (genus Draco, Latin for dragon) and Triassic fossil reptiles such as Kuehneosaurus, but the Triassic look-alikes lived over 100 million years before Xianglong. Despite the 11-centimetre (4.3 in) "rib-span", the lizard might have been quite agile in the air, possibly to escape the feathered dinosaurs that coexisted with it.

Xianglong had slightly curved claws, indicating that it was arboreal. Of course, it needed to be in order to get in its "gliding mode".

Xu Xing, a Chinese paleontologist and one of the describers of Xianglong, states that it is possible Xianlong could have glided as much as half a football field, much farther than that of the modern Draco.