Cryptovolans

From Wikipedia, the free encyclopedia

Cryptovolans
Fossil range: Early Cretaceous

Kingdom:	Animalia
Phylum:	Chordata
Class:	Sauropsida
Superorder:	Dinosauria
Order:	Saurischia
Suborder:	Theropoda
Family:	Dromaeosauridae
Genus:	Cryptovolans Czerkas et al., 2002

Species

C. pauli Czerkas et al., 2002 (type)

Cryptovolans (meaning 'hidden flyer') is a genus of feathered, dromaeosaurid, dinosaur represented by a 90 cm long individual preserved in 3 fossils. It may not have any significant differences from the genus Microraptor, in which case the name Cryptovolans would be abandoned as a junior synonym. Its specific name, C. pauli, honours paleontologist Gregory S. Paul. This fossil is in the collection of the Paleontology Museum of Beipiao, in Liaoning, China. The type specimens were collected at the Jiufotang site. They are referred to as LPM 0200 (or BPM 1 3-13), LPM 0201, and LPM 0159. Norell et al. (2002) were the first to publish a study of the specimens, but they did not assign the animal a formal name.^[1] Czerkas et al. (2002) coined the name "Cryptovolans" and diagnosed this genus on the basis of primary feathers (which in the authors' opinion made it a bird), an ossified sternum, and a third finger with a short phalanx III-3. Some of the feathers Czerkas described as primary were actually attached to the leg, rather than the arm. This, along with all of the other diagnostic characters are also present in the genus Microraptor, which was first described earlier than Cryptovolans.^[2]However, BPM 1 3-23 has a longer tail, proportionately, than other Microraptor specimens that had been described by 2002.^[1]

[edit] Flight capability

Norell et al (2002) described BPM 1 3-23 (nicknaming it "Chong") as the first dinosaur known to have asymmetric, primary flight feathers on its legs as well as on its arms.^[3]It also arguably had such feathers on the end of its long tail, as well as on the rest of its body, and other unusual adaptations such as fused sternal plates (Czerkas, 2002).

Czerkas (2002) mistakenly described the fossil as having no long feathers on its legs, but only on its arms, as he illustrated on the cover of his book. He also believed that Cryptovolans may have been able to fly better than Archaeopteryx, the animal usually referred to as the earliest known bird. Possessing an incipiently keeled sternum and ribs with uncinate processes, Cryptovolans has modern bird features which are absent in Archaeopteryx. Czerkas cited the fact that this possibly volant animal is also very clearly a dromaeosaurid to suggest that the Dromaeosauridae might actually be a basal bird group, and that later (larger) species such as Deinonychus were secondarily flightless (Czerkas, 2002). Current evidence for this theory is contradictory, and some of the modern bird-like features in Cryptovolans may have evolved independently. Regardless of whether dromaeosaurids are a sister group to birds or actual members of Aves, there is unanimity that they are part of the Maniraptoran suborder of theropod dinosaurs. Some researchers, however, such as Czerkas (2002), argue that maniraptors including modern birds and Cryptovolans are not theropods at all, but members of a hypothetical pre-theropodan group of arboreal archosaurs. According to Czerkas, one branch of this group became the ground-dwelling maniraptorans, and another branch became the true birds, a group that would include Cryptovolans and other dromaeosaurids, some of which were secondarily flightless.

[edit] References

Czerkas, S.A., Zhang, D., Li, J., and Li, Y. (2002). "Flying Dromaeosaurs", in Czerkas, S.J.: Feathered Dinosaurs and the Origin of Flight: The Dinosaur Museum Journal 1. Blanding: The Dinosaur Museum, 16-26

Senter, P., Barsold, R., Britt, B.B., and Burnham, D.A. (2004). "Systematics and evolution of Dromaeosauridae (Dinosauria, Theropoda)." Bulletin of the Gunma Museum of Natural History, 8: 1-20..