Editing Microraptor (section)

===Study and debate===
[[File:Microraptor zhaoianus.jpg|thumb|upright|Fossil specimen]]
Norell ''et al.'' (2002) described BPM 1 3-13 as the first dinosaur known to have flight feathers on its legs as well as on its arms.<ref name="Norelletal02">{{cite journal | last1 = Norell | first1 = Mark | last2 = Ji | first2 = Qiang | last3 = Gao | first3 = Keqin | last4 = Yuan | first4 = Chongxi | last5 = Zhao | first5 = Yibin | last6 = Wang | first6 = Lixia | year = 2002 | title = 'Modern' feathers on a non-avian dinosaur | journal = Nature | volume = 416 | issue = 6876| pages = 36–7 | doi=10.1038/416036a| pmid = 11882883 | bibcode = 2002Natur.416...36N | s2cid = 4410791 }}</ref>

Czerkas (2002) mistakenly described the fossil as having no long feathers on its legs, but only on its hands and arms, as he illustrated on the cover of his book ''Feathered Dinosaurs and the Origin of Flight''.<ref name="Czerkas2002">Czerkas, Sylvia J. ed. (2002) "Feathered Dinosaurs and the Origin of Flight" The Dinosaur Museum Journal Volume 1. Blanding, Utah, USA. The Dinosaur Museum, August 1, 2002</ref> In his discussion of ''Cryptovolans'' in this book, Czerkas strongly denounces Norell's conclusions; "The misinterpretation of the primary wing feathers as being from the hind legs stems directly to [''sic''] seeing what one believes and wants to see".<ref name="Czerkas2002"/> Czerkas also denounced Norell for failing to conclude that [[Dromaeosauridae|dromaeosaurs]] are birds, accusing him of succumbing to "...the blinding influences of preconceived ideas."<ref name="Czerkas2002"/> The [[crown group]] definition of Aves, as a subset of [[Avialae]], the explicit definition of the term "bird" that Norell employs, would definitely exclude BPM 1 3-13. However, he does not consider the specimen to belong to Avialae either.<ref name="Norelletal02"/>

Czerkas's interpretation of the hindleg feathers noted by Norell proved to be incorrect the following year when additional specimens of ''Microraptor'' were published by Xu and colleagues, showing a distinctive "hindwing" completely separate from the forelimb wing. The first of these specimens was discovered in 2001, and between 2001 and 2003 four more specimens were bought from private collectors by Xu's museum, the [[Institute of Vertebrate Paleontology and Paleoanthropology]]. Xu also considered these specimens, most of which had hindwings and proportional differences from the original ''Microraptor'' specimen, to be a new species, which he named ''Microraptor gui''. However, Senter also questioned this classification, noting that as with ''Cryptovolans'', most of the differences appeared to correspond with size, and likely age differences.<ref name=senteretal2004/> Two further specimens, classified as ''M. zhaoianus'' in 2002 (''M. gui'' had not yet been named), have also been described by Hwang and colleagues.<ref name="hwangetal2002"/>

Czerkas also believed that the animal may have been able to fly better than ''[[Archaeopteryx]]'', the animal usually referred to as the earliest known bird. He cited the fused sternum and asymmetrical feathers, and argued that ''Microraptor'' has modern bird features that make it more derived than ''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). The current consensus is that there is not enough evidence to conclude whether dromaeosaurs descended from an ancestor with some aerodynamic abilities. The work of Xu ''et al.'' (2003) suggested that basal dromaeosaurs were probably small, arboreal, and could glide.<ref name=xuetal2003>{{cite journal | last1 = Xing | first1 = X. | last2 = Zhou | first2 = Z. | last3 = Wang | first3 = X. | last4 = Kuang | first4 = X. | last5 = Zhang | first5 = F. | last6 = Du | first6 = X. | year = 2003 | title = Four-winged dinosaurs from China | journal = Nature | volume = 421 | issue = 6921| pages = 335–340 | bibcode = 2003Natur.421..335X | doi = 10.1038/nature01342 | pmid = 12540892 | s2cid = 1160118 | url = http://doc.rero.ch/record/15275/files/PAL_E2574.pdf }}</ref> The work of Turner ''et al.'' (2007) suggested that the ancestral dromaeosaur could not glide or fly, but that there was good evidence that it was small-bodied (around 65&nbsp;cm long and 600–700&nbsp;g in mass).<ref name="Turneretal07"/>