Editing Microraptor

{{Short description|Extinct genus of dinosaurs}}
{{Automatic taxobox
| fossil_range = [[Early Cretaceous]], {{fossil range|120}}
| image = Microraptor gui holotype.png
| image_upright = 1.15
| image_caption = Fossil specimen, with white arrows pointing at preserved feathers
| taxon = Microraptor
| authority = [[Xu Xing (paleontologist)|Xu]] ''et al.'', 2000
| type_species = {{extinct}}'''''Microraptor zhaoianus'''''
| type_species_authority = Xu ''et al.'', 2000
| subdivision_ranks = Other [[species]]
| subdivision =
* {{extinct}}'''''M. gui''''' <small>Xu ''et al.'', 2003</small>
* {{extinct}}'''''M. hanqingi''''' <small>Gong ''et al.'', 2012</small>
| synonyms = 
* ''Cryptovolans'' <small>Czerkas ''et al.'', 2002</small>
* "Tetrapterornis" <small>Miller, 2004 (''[[nomen nudum]]'')</small><ref name="Miller 2004">{{cite journal |last=Miller |first=Z.M. |date=2004 |title=A new phylogeny of Dromaeosauridae |journal=Student Showcase Journal, University of Alaska Anchorage |volume=20 |pages=123–158 |url=https://core.ac.uk/reader/162574940}}</ref>
}}

'''''Microraptor''''' ([[Greek language|Greek]], μικρός, ''mīkros'': "small"; [[Latin language|Latin]], ''raptor'': "one who seizes") is a [[genus]] of small, four-winged [[dromaeosaurid]] [[dinosaur]]s. Numerous well-preserved [[fossil]] specimens have been recovered from [[Liaoning]], [[China]]. They date from the early [[Cretaceous]] [[Jiufotang Formation]] ([[Aptian]] stage), 125 to 120&nbsp;million [[year]]s ago. Three species have been named (''M. zhaoianus'', ''M. gui'', and ''M. hanqingi''), though further study has suggested that all of them represent variation in a single species, which is properly called ''M. zhaoianus''. '''''Cryptovolans''''', initially described as another four-winged dinosaur, is usually considered to be a synonym of ''Microraptor''.<ref name="senteretal2004">{{cite journal | last1 = Senter | first1 = P. | last2 = Barsold | first2 = R. | last3 = Britt | first3 = B.B. | last4 = Burnham | first4 = D.A. | year = 2004 | title = Systematics and evolution of Dromaeosauridae (Dinosauria, Theropoda) | journal = Bulletin of the Gunma Museum of Natural History | volume = 8 | pages = 1–20 }}</ref>

Like ''[[Archaeopteryx]]'', well-preserved fossils of ''Microraptor'' provide important evidence about the evolutionary relationship between [[bird]]s and earlier dinosaurs. ''Microraptor'' had long [[pennaceous feather]]s that formed aerodynamic surfaces on the arms and tail but also on the legs. This led paleontologist [[Xu Xing (paleontologist)|Xu Xing]] in 2003 to describe the first specimen to preserve this feature as a "four-winged dinosaur" and to speculate that it may have [[Gliding flight|glided]] using all four limbs for lift. Subsequent studies have suggested that ''Microraptor'' was capable of powered flight as well.

''Microraptor'' was among the most abundant non-[[Avialae|avialan]] dinosaurs in its ecosystem, and the genus is represented by more fossils than any other dromaeosaurid, with possibly over 300 fossil specimens represented across various museum collections.<ref name=alexanderetal2010/> One specimen in particular shows evidence of active primary feather [[moulting]], which is one of the few known fossil evidence of such behavior among pennaraptoran dinosaurs.<ref>{{Cite journal|last1=Kiat |first1=Y. |last2=O'Connor |first2=J. K. |year=2023 |title=Rarity of molt evidence in early pennaraptoran dinosaurs suggests annual molt evolved later among Neornithes |journal=Communications Biology |volume=6 |issue=1 |at=687 |doi=10.1038/s42003-023-05048-x |pmid=37400509 |pmc=10317961 |doi-access=free }}</ref>

==History==
===Naming controversy===
{{Main|Archaeoraptor}}
[[File:Archaeoraptor-Paleozoological Museum of China.jpg|alt=|thumb|The "[[Archaeoraptor]]" fossil; the tail belongs to ''Microraptor'']]
The initial naming of ''Microraptor'' was controversial, because of the unusual circumstances of its first description. The first specimen to be described was part of a chimeric specimen—a patchwork of different feathered dinosaur species (''Microraptor'' itself, ''[[Yanornis]]'' and an as-of-yet undescribed third species) assembled from multiple specimens in China and smuggled to the USA for [[Fossil collecting|sale]]. After the forgery was revealed by [[Xu Xing (paleontologist)|Xu Xing]] of [[Beijing]]'s [[Institute of Vertebrate Paleontology and Paleoanthropology]], [[Storrs L. Olson]], curator of birds in the [[National Museum of Natural History]] of the [[Smithsonian Institution]], published a description of the Microraptor's tail in an obscure journal, giving it the name ''Archaeoraptor liaoningensis'' in an attempt to remove the name from the paleornithological record by assigning it to the part least likely to be a bird.<ref name="olson2000">Olson, S.L. (2000). "Countdown to Piltdown at ''National Geographic'': the rise and fall of ''Archaeoraptor''." ''Backbone'', '''13'''(2) (April): 1–3.</ref> However, Xu had discovered the remains of the specimen from which the tail had been taken and published a description of it later that year, giving it the name ''Microraptor zhaoianus''.<ref name="Xu2000">Xu, X., Zhou, Z., and Wang, X. (2000). "The smallest known non-avian theropod dinosaur." ''Nature'', '''408''' (December): 705-708.{{cite web |url=http://research.amnh.org/%7Esunny/microraptor.pdf |title=Archived copy |access-date=2008-12-17 |url-status=dead |archive-url=https://web.archive.org/web/20081217154907/http://research.amnh.org/%7Esunny/microraptor.pdf |archive-date=2008-12-17 }}</ref>

Since the two names designate the same individual as the [[Type (biology)|type]] specimen, ''Microraptor zhaoianus'' would have been a [[junior objective synonym]] of ''Archaeoraptor liaoningensis'' and the latter, if valid, would have had priority under the [[International Code of Zoological Nomenclature]]. However, there is some doubt whether Olson in fact succeeded in meeting all the formal requirements for establishing a new taxon. Namely, Olson designated the specimen as a [[lectotype]], before an actual type species was formally erected.<ref name=dmlarchaeoraptor>Creisler, B. (2002). "[http://dml.cmnh.org/2001Jan/msg00092.html Archaeoraptor still a nomen nudum] {{Webarchive|url=https://web.archive.org/web/20080725160846/http://dml.cmnh.org/2001Jan/msg00092.html |date=2008-07-25 }}." Message to the Dinosaur Mailing List, 4 Jan 2001. accessed 23 Sep 2009.</ref> A similar situation arose with ''[[Tyrannosaurus rex]]'' and ''Manospondylus gigas'', in which the former became a ''nomen protectum'' and the latter a ''nomen oblitum'' due to revisions in the ICZN rules that took place on December 31, 1999.<ref name="sowhyhasn">{{Cite web|title=So why hasn't Tyrannosaurus been renamed Manospondylus?|url=http://www.miketaylor.org.uk/dino/faq/s-class/priority/|access-date=2023-02-07|website=The Dinosaur FAQ |last=Taylor |first=M. |author-link=Michael P. Taylor |date=2002-08-27}}</ref> In addition, Xu's name for the type specimen (''Microraptor'') was subsequently used more frequently than the original name; as such, this and the chimeric nature of the specimen would render the name "Archaeoraptor" a ''nomen vanum'' (as it was improperly described) and the junior synonym ''Microraptor'' a ''nomen protectum'' (as it's been used in more published works than "Archaeoraptor" and was properly described).<ref name=dmlarchaeoraptorvmicroraptor>Williams, T. (2002). "[http://dml.cmnh.org/2001Jan/msg00020.html Archaeoraptor v Microraptor] {{Webarchive|url=https://web.archive.org/web/20160303215023/http://dml.cmnh.org/2001Jan/msg00020.html |date=2016-03-03 }}." Message to the Dinosaur Mailing List, 1 Jan 2001. accessed 30 Sept 2014.</ref>

===Additional specimens===
[[File:Microraptor Skeletons by Qilong.jpg|thumb|Skeletal restorations of various specimens]]
The first specimen referred to ''Microraptor'' represented a small individual and included faint feather remnants, but was otherwise not well preserved and lacked a skull.
In 2002 [[Mark Norell]] et al. described another specimen, BPM 1 3-13, which they did not name or refer to an existing species.<ref name="norelletal02">Norell, Mark, Ji, Qiang, Gao, Keqin, Yuan, Chongxi, Zhao, Yibin, Wang, Lixia. (2002). "'Modern' feathers on a non-avian dinosaur". ''Nature'', 416: pp. 36. 7 March 2002.></ref> Later that year [[Stephen A. Czerkas|Stephen Czerkas]] et al. named the specimen ''Cryptovolans pauli'', and referred two additional specimens (the first to show well-preserved feathers) to this species. The generic name was derived from Greek ''kryptos'', "hidden", and [[Latin]] ''volans'', "flying". The [[specific name (zoology)|specific name]], ''pauli'', honors [[Paleontology|paleontologist]] [[Gregory S. Paul]], who had long proposed that dromaeosaurids evolved from flying ancestors.<ref name="Czerkas2002"/>

The [[type specimen]]s of ''C. pauli'' were collected from the [[Jiufotang Formation]], dating from the early [[Albian]] and now belong to the collection of the Paleontology Museum of Beipiao, in [[Liaoning]], China. They are referred to by the inventory numbers LPM 0200, the [[holotype]]; LPM 0201, its counterslab (slab and counterslab together represent the earlier BPM 1 3-13); and the [[paratype]] LPM 0159, a smaller skeleton. Both individuals are preserved as articulated compression fossils; they are reasonably complete but partially damaged.<ref name="Czerkas2002"/>
[[File:Microraptor-Beijing Museum of Natural History.jpg|alt=|left|thumb|Specimen at the [[Beijing Museum of Natural History]]]]
Czerkas ''et al.'' (2002) diagnosed the genus on the basis of having primary feathers (which in the authors' opinion made it a [[bird]]), a co-ossified sternum, a tail consisting of 28 to 30 vertebrae and a third finger with a short phalanx III-3.<ref name="Czerkas2002"/> Some of the feathers Czerkas described as primary were actually attached to the leg, rather than the arm. This, along with most of the other diagnostic characters, is also present in the genus ''Microraptor'', which was first described earlier than ''Cryptovolans''.<ref name="Xuetal03">{{cite journal | last1 = Xu | first1 = Xing | last2 = Zhou | first2 = Zhinghe | last3 = Wang | first3 = Xiaolin | last4 = KUang | first4 = Xuewen | last5 = Zhang | first5 = Fucheng | last6 = Du | first6 = Xiangke | year = 2003 | title = Four-winged dinosaurs from China | journal = Nature | volume = 421 | issue = 6921| pages = 335–340 | doi=10.1038/nature01342 | pmid=12540892| bibcode = 2003Natur.421..335X | s2cid = 1160118 | url = http://doc.rero.ch/record/15275/files/PAL_E2574.pdf }}</ref> However, BPM 1 3-13 has a longer tail, proportionately, than other ''Microraptor'' specimens that had been described by 2002, which have 24 to 26 tail vertebrae.<ref name="norelletal02"/>

Subsequent studies (and more specimens of ''Microraptor'') have shown that the features used to distinguish ''Cryptovolans'' are not unique, but are present to varying degrees across various specimens. In a review by Phil Senter and colleagues in 2004, the scientists suggested that all these features represented individual variation across various age groups of a single ''Microraptor'' species, making the name ''Cryptovolans pauli'' and ''Microraptor gui'' junior synonyms of ''Microraptor zhaoianus''.<ref name="senteretal2004"/> Many other researchers, including Alan Feduccia and Tom Holtz, have since supported its synonymy.<ref name="Holtz2008">Holtz, Thomas R. Jr. (2011) ''Dinosaurs: The Most Complete, Up-to-Date Encyclopedia for Dinosaur Lovers of All Ages,'' [http://www.geol.umd.edu/~tholtz/dinoappendix/HoltzappendixWinter2010.pdf Winter 2010 Appendix.]</ref><ref name=FLH05>{{cite journal|last1=Feduccia |first1=A. |year=2005 |title=Do feathered dinosaurs exist? Testing the hypothesis on neontological and paleontological evidence |journal=Journal of Morphology |volume=266 |issue=2 |pages=125–166 |pmid=16217748 |doi=10.1002/jmor.10382|last2=Lingham-Soliar|first2=T|last3=Hinchliffe|first3=JR|s2cid=15079072 }}</ref> ''M. gui'' has been accepted as a distinct species with the specimen reported in 2013 being distinguishable from the type specimen of ''M. zhaoianus''.<ref name=Xing13/>

A new specimen of ''Microraptor'', BMNHC PH881, showed several features previously unknown in the animal, including the probably glossy-black iridescent plumage coloration. The new specimen also featured a bifurcated tailfan, similar in shape to previously known ''Microraptor'' tailfans except sporting a pair of long, narrow feathers at the center of the fan. The new specimen also showed no sign of the nuchal crest, indicating that the crest inferred from the holotype specimen may be an artifact of [[taphonomy|taphonomic]] distortion.<ref name="iridescence"/><ref name="iridescence2"/>

Numerous further specimens likely belonging to ''Microraptor'' have been uncovered, all from the Shangheshou Bed of the [[Jiufotang Formation]] in Liaoning, China. In fact, ''Microraptor'' is the most abundant non-avialan dinosaur fossil type found in this formation.<ref name="xu&norell2006">{{cite journal | last1 = Xu | first1 = X. | last2 = Norell | first2 = M.A. | year = 2006 | title = Non-Avian dinosaur fossils from the Lower Cretaceous Jehol Group of western Liaoning, China | doi = 10.1002/gj.1044 | journal = Geological Journal | volume = 41 | issue = 3–4| pages = 419–437 | bibcode = 2006GeolJ..41..419X | s2cid = 32369205 }}</ref> In 2010, it was reported that there were over 300 undescribed specimens attributable to ''Microraptor'' or its close relatives among the collections of several Chinese museums, though many had been altered or composited by private fossil collectors.<ref name=alexanderetal2010/>

===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"/>

==Description==
[[File:Microraptor scale.png|thumb|left|Wingspan and body size compared with a human]]
''Microraptor'' was among the [[Dinosaur size|smallest-known non-avian dinosaurs]], with the holotype of ''M. gui'' measuring {{convert|77|cm|ft}} in length, {{convert|88|-|94|cm|ft}} in wingspan and weighing {{convert|0.5|-|1.4|kg}}.<ref name="chatterjee2007"/><ref>{{Cite journal|last1=Xu |first1= Xing|last2=Qin|first2=Zi-Chuan|year=2017|title=A new tiny dromaeosaurid dinosaur from the Lower Cretaceous Jehol Group of western Liaoning and niche differentiation among the Jehol dromaeosaurids|journal=Vertebrata PalAsiatica|volume=55|issue=2|pages=129–144|url=http://www.ivpp.cas.cn/cbw/gjzdwxb/pressonline/201704/P020170410587218147108.pdf|s2cid=44178386}}</ref><ref name=D20/> There are larger specimens which would have measured at least {{convert|80|cm|ft}} in length, more than {{convert|99|cm|ft}} in wingspan and weighed {{convert|1.25|-|1.88|kg}}.<ref name=D20/>{{efn|The wingspan estimate is based on the equation presented in the study by Dececchi ''et al.'' (2016) which states that the wingspan of the paravians in the study would have been 2.1 times the wing length.<ref name=Dececchi_etal_2016/> In case of ''Microraptor'', the holotype had a wing length of {{convert|42|cm|ft}}, resulting in a wingspan of more than {{convert|88|cm|ft}}. The larger specimen QV1002 measured {{convert|3|cm|in}} longer than the holotype in precaudal length, and had wing length of {{convert|47.2|cm|ft}}, resulting in a wingspan of more than {{convert|99|cm|ft}}.<ref name=D20/>}} Aside from their extremely small size, ''Microraptor'' were among the first non-[[Avialae|avialan]] dinosaurs discovered with the impressions of feathers and wings. Seven specimens of ''M. zhaoianus'' have been described in detail, from which most feather impressions are known. Unusual even among early birds and feathered dinosaurs, ''Microraptor'' is one of the few known bird precursors to sport long flight feathers on the legs as well as the wings. Their bodies had a thick covering of feathers, with a diamond-shaped fan on the end of the tail (possibly for added stability during flight). Xu ''et al.'' (2003) compared the longer plumes on ''Microraptor''{{'}}s head to those of the [[Philippine eagle]]. Bands of dark and light present on some specimens may indicate color patterns present in life,<ref name="hwangetal2002"/> though at least some individuals almost certainly possessed an iridescent black coloration.<ref name="iridescence"/>

===Distinguishing anatomical features===
A diagnosis is a statement of the anatomical features of an organism (or group) that collectively distinguish it from all other organisms. Some, but not all, of the features in a diagnosis are also autapomorphies. An autapomorphy is a distinctive anatomical feature that is unique to a given organism. Several anatomical features found in ''Microraptor'', such as a combination of unserrated and partially serrated teeth with constricted 'waists', and unusually long upper arm bones, are shared with both primitive avians and primitive [[Troodontidae|troodontids]]. ''Microraptor'' is particularly similar to the basal troodontid ''[[Sinovenator]]''; in their 2002 description of two ''M. zhaoianus'' specimens, Hwang ''et al.'' note that this is not particularly surprising, given that both ''Microraptor'' and ''Sinovenator'' are very primitive members of two closely related groups, and both are close to the [[Dromaeosauridae|deinonychosaurian]] split between dromaeosaurids and troodontids.<ref name="hwangetal2002">Hwang, S.H., Norell, M.A., Ji, Q., and Gao, K. (2002). "New Specimens of ''Microraptor zhaoianus'' (Theropoda: Dromaeosauridae) from Northeastern China." ''American Museum Novitates'', 3381: 44pp.</ref>

===Coloration===
[[File:Microraptor Restoration.png|thumb|[[Paleoart|Restoration]] of ''M. gui'' with coloration based on fossilized melanosomes]]
In March 2012, Quanguo Li ''et al.'' determined the plumage coloration of ''Microraptor'' based on the new specimen BMNHC PH881, which also showed several other features previously unknown in ''Microraptor''. By analyzing the fossilized melanosomes (pigment cells) in the fossil with [[scanning electron microscope]] techniques, the researchers compared their arrangements to those of modern birds. In ''Microraptor'', these cells were shaped in a manner consistent with black, glossy coloration in modern birds. These rod-shaped, narrow melanosomes were arranged in stacked layers, much like those of a modern [[Common starling|starling]], and indicated [[iridescence]] in the plumage of ''Microraptor''. Though the researchers state that the true function of the iridescence is yet unknown, it has been suggested that the tiny dromaeosaur was using its glossy coat as a form of communication or sexual display, much as in modern iridescent birds.<ref name="iridescence">{{cite journal| last1 = Li| first1 = Q. | last2 = Gao | first2 = K.-Q. | last3 = Meng | first3 = Q. | last4 = Clarke | first4 = J.A. | last5 = Shawkey | first5 = M.D. | last6 = D'Alba | first6 = L. | last7 = Pei | first7 = R. | last8 = Ellision | first8 = M. | last9 = Norell | first9 = M.A. | last10 = Vinther | first10 = J.| title = Reconstruction of ''Microraptor'' and the Evolution of Iridescent Plumage| journal = Science| volume = 335| pages = 1215–1219| date = 2012| doi = 10.1126/science.1213780| pmid=22403389 | issue = 6073| bibcode = 2012Sci...335.1215L| s2cid = 206537426 }}</ref><ref name="iridescence2">{{cite news| last = Wilford| first = John Noble| title = Feathers Worth a 2nd Look Found on a Tiny Dinosaur| newspaper = The New York Times| location = New York| date = 8 March 2012| url = https://www.nytimes.com/2012/03/09/science/feather-cells-tell-of-microraptors-crowlike-sheen.html| access-date = 22 April 2012}}</ref>

==Classification==
[[File:Dromaeosaurs.png|thumb|Size of ''Microraptor'' (1) compared with other [[Dromaeosauridae|dromaeosaurs]]]]
[[File:Shandong Microraptor.jpg|thumb|Specimen in the Shandong Tianyu Museum of Nature]]
The cladogram below follows a 2012 analysis by paleontologists Phil Senter, James I. Kirkland, Donald D. DeBlieux, Scott Madsen and Natalie Toth.<ref name=Yurgovuchia>{{Cite journal | last1 = Senter | first1 = P. | last2 = Kirkland | first2 = J. I. | last3 = Deblieux | first3 = D. D. | last4 = Madsen | first4 = S. | last5 = Toth | first5 = N. | editor1-last = Dodson | editor1-first = Peter | title = New Dromaeosaurids (Dinosauria: Theropoda) from the Lower Cretaceous of Utah, and the Evolution of the Dromaeosaurid Tail | doi = 10.1371/journal.pone.0036790 | journal = PLOS ONE | volume = 7 | issue = 5 | pages = e36790 | year = 2012 | pmid = 22615813| pmc = 3352940| bibcode = 2012PLoSO...736790S | doi-access = free }}</ref>

{{clade| style=font-size:100%;line-height:100%
|label1=[[Dromaeosauridae]]
|1={{clade
   |1=''[[Xiaotingia]]'' [[File:Xiaotingia .jpg|80px]]
   |2={{clade
      |1=[[Unenlagiinae]] [[File:Austroraptor Restoration (flipped).png|80px]]
      |2={{clade
         |1=''[[Shanag]]'' [[File:Shanag.jpg|80px]]
         |2={{clade
            |label1=[[Eudromaeosauria]]
            |1={{clade
               |1=[[Saurornitholestinae]] 
               |2={{clade
                  |1=[[Velociraptorinae]] [[File:Fred Wierum Velociraptor.png|80px]]
                  |2=[[Dromaeosaurinae]] [[File:Deinonychus ewilloughby (flipped).png|80px]] }} }}
            |label2=[[Microraptoria]]
            |2={{clade
               |1=''[[Tianyuraptor]]'' 
               |2={{clade
                  |1=''[[Hesperonychus]]'' 
                  |2={{clade
                     |1={{clade
                        |1='''''Microraptor sp.''''' 
                        |2={{clade
                           |1='''''Microraptor gui''''' [[File:Fred Wierum Microraptor.png|80px]]
                           |2='''''Microraptor zhaoianus''''' }} }}
                     |2={{clade
                        |1=''[[Cryptovolans]]''
                        |2=''[[Graciliraptor]]'' [[File:Graciliraptor.jpg|80px]]
                        |3=''[[Sinornithosaurus]]'' [[File:Sinornithosaurus.jpg|80px]] }} }} }} }} }} }} }} }} }}

In a 2024 paper which reported the smallest known juvenile specimen of ''Microraptor'', Wang and Pei included [[microraptoria]]ns and [[eudromaeosauria]]ns within a new clade Serraraptoria.<ref>{{Cite journal|last1=Wang |first1=R. |last2=Pei |first2=R. |year=2024 |title=The smallest known specimen of ''Microraptor'' (Dinosauria: Dromaeosauridae) from the Jiufotang Formation in northeastern China |journal=Historical Biology: An International Journal of Paleobiology |pages=1–11 |doi=10.1080/08912963.2024.2385604 }}</ref>

==Paleobiology==
===Wings and flight===
''Microraptor'' had four [[wing]]s, one on each of its forelimbs and hindlimbs, somewhat resembling one possible arrangement of the quartet of flight surfaces on a [[tandem wing]] aircraft of today. It had long [[pennaceous feather]]s on arms and hands {{convert|10|–|20|cm|in|adj=mid|long|abbr=on}} with legs and feet {{convert|11|–|15|cm|in|adj=mid|long|abbr=on}}. The long feathers on the legs of ''Microraptor'' were true flight feathers as seen in modern [[bird]]s, with asymmetrical vanes on the arm, leg, and tail feathers. As in modern bird wings, ''Microraptor'' had both primary (anchored to the hand) and secondary (anchored to the arm) flight feathers. This standard wing pattern was mirrored on the hindlegs, with [[flight feather]]s anchored to the upper foot bones as well as the upper and lower leg. Though not apparent in most fossils under natural light, due to obstruction from decayed soft tissue, the feather bases extended close to or in contact with the bones, as in modern birds, providing strong anchor points.<ref name=hone2010>{{cite journal | last1 = Hone | first1 = D.W.E. | last2 = Tischlinger | first2 = H. | last3 = Xu | first3 = X. | last4 = Zhang | first4 = F. | year = 2010 | title = The extent of the preserved feathers on the four-winged dinosaur ''Microraptor gui'' under ultraviolet light | journal = PLOS ONE | volume = 5 | issue = 2| page = e9223 | doi = 10.1371/journal.pone.0009223 | pmid=20169153 | pmc=2821398 | bibcode = 2010PLoSO...5.9223H | doi-access = free }}</ref>

It was originally thought that ''Microraptor'' was a [[Gliding flight|glider]], and probably lived mainly in trees, because the hindwings anchored to the feet of ''Microraptor'' would have hindered their ability to run on the ground.<ref name="Xuetal2003">Xu, X., Zhou, Z., Wang, X., Kuang, X., Zhang, F. and Du, X. (2003). "Four-winged dinosaurs from China." ''Nature'', '''421'''(6921): 335-340, 23 Jan 2003.</ref> Some paleontologists have suggested that feathered dinosaurs used their wings to parachute from trees, possibly to attack or ambush prey on the ground, as a precursor to gliding or true flight.<ref name="benson2012"/> In their 2007 study, Chatterjee and Templin tested this hypothesis as well, and found that the combined wing surface of ''Microraptor'' was too narrow to successfully parachute to the ground without injury from any significant height. However, the authors did leave open the possibility that ''Microraptor'' could have parachuted short distances, as between closely spaced tree branches.<ref name="chatterjee2007"/><ref name="benson2012">{{cite book|author1=Benson, R.B.J. |author2=Brussatte, S. |year=2012|title=Prehistoric Life|location=London|publisher=Dorling Kindersley|page=332|isbn=978-0-7566-9910-9}}</ref> Wind tunnel experiments have demonstrated that sustaining a high-lift coefficient at the expense of high drag was likely the most efficient strategy for ''Microraptor'' when gliding between low elevations. ''Microraptor'' did not require a sophisticated, 'modern' wing morphology to be an effective glider.<ref>{{cite journal | last1 = Dyke | first1 = Gareth | last2 = de Kat | first2 = Roeland | last3 = Palmer | first3 = Colin | last4 = van der Kindere | first4 = Jacques | last5 = Naish | first5 = Darren | last6 = Ganapathisubramani | first6 = Bharathram | year = 2013 | title = Aerodynamic performance of the feathered dinosaur Microraptor and the evolution of feathered flight | journal = Nature Communications | volume = 4 | page = 2489 | doi = 10.1038/ncomms3489 | pmid = 24048346 | bibcode = 2013NatCo...4.2489D | doi-access = free }}</ref> However, the idea that ''Microraptor'' was an arboreal glider relies on it to have regularly climbed or even lived in trees, when study of its anatomy have shown that its limb proportions fall in line with modern ground birds rather than climbers, and its skeleton shows none of the expected adaptations in animals specialized for climbing trees.<ref>{{Cite journal|last1=Dececchi|first1=T. Alexander|last2=Larsson|first2=Hans C. E.|date=2011-08-09|editor-last=Farke|editor-first=Andrew Allen|title=Assessing Arboreal Adaptations of Bird Antecedents: Testing the Ecological Setting of the Origin of the Avian Flight Stroke|journal=PLOS ONE|language=en|volume=6|issue=8|pages=e22292|doi=10.1371/journal.pone.0022292|issn=1932-6203|pmc=3153453|pmid=21857918|bibcode=2011PLoSO...622292D|doi-access=free}}</ref><ref name=Dececchi_etal_2016>{{cite journal | last1 = Dececchi | first1 = T.A. | last2 = Larsson | first2 = H.C.E. | last3 = Habib | first3 = M.B. | year = 2016 | title = The wings before the bird: an evaluation of flapping-based locomotory hypotheses in bird antecedents | journal = PeerJ | volume = 4 | page = e2159 | doi = 10.7717/peerj.2159 | pmid=27441115 | pmc=4941780 | doi-access = free }}</ref>

[[File:Microraptor gui holotype under UV light.png|thumb|''M. gui'' [[holotype]] under two different UV light filters, revealing the extent of preserved feathers and soft tissue]]
Describing specimens originally referenced as a distinctive species (''Cryptovolans pauli''), paleontologist Stephen Czerkas argued ''Microraptor'' may have been a powered flier, and indeed possibly a better flyer than ''[[Archaeopteryx]]''. He noted that the ''Microraptor's'' fused sternum, asymmetrical feathers, and features of the shoulder girdle indicated that it could fly under its own power, rather than merely gliding. Today, most scientists agree that ''Microraptor'' had the anatomical features expected of a flying animal, though it would have been a less advanced form of flight compared to birds. For example, some studies suggest the shoulder joint was too primitive to allow a full flapping flight stroke. In the ancestral anatomy of theropod dinosaurs, the shoulder socket faced downward and slightly backward, making it impossible for the animals to raise their arms vertically, a prerequisite for the flapping flight stroke in birds. Studies of maniraptoran anatomy have suggested that the shoulder socket did not shift into the bird-like position of a high, upward orientation close to the [[vertebra]]l column until relatively advanced avialans like the [[enantiornithes]] appeared.<ref name=senter2006>{{cite journal | last1 = Senter | first1 = P | year = 2006 | title = Scapular orientation in theropods and basal birds, and the origin of flapping flight | journal = Acta Palaeontol. Pol. | volume = 51 | pages = 305–313 }}</ref> However, other scientists have argued that the shoulder girdle in some [[Paraves|paravian]] theropods, including ''Microraptor'', is curved in such a way that the shoulder joint could only have been positioned high on the back, allowing for a nearly vertical upstroke of the wing. This possibly advanced shoulder anatomy, combined with the presence of a [[Patagium|propatagium]] linking the wrist to the shoulder (which fills the space in front of the flexed wing and may support the wing against drag in modern birds) and an [[alula]], much like a "thumb-like" form of [[leading edge slot]], may indicate that ''Microraptor'' was capable of true, powered flight.<ref name=avianancestry>{{Cite journal|author1=Federico L. Agnolín |author2=Fernando E. Novas |name-list-style=amp |year=2013 |title=Avian ancestors. A review of the phylogenetic relationships of the theropods Unenlagiidae, Microraptoria, ''Anchiornis'' and Scansoriopterygidae |journal=SpringerBriefs in Earth System Sciences |pages=1–96 |doi=10.1007/978-94-007-5637-3 |isbn=978-94-007-5636-6 |s2cid=199493087 }}</ref>

Other studies have demonstrated that the wings of ''Microraptor'' were large enough to generate the lift necessary for powered launching into flight even without a fully vertical flight stroke. A 2016 study of incipient flight ability in paravians demonstrated that ''Microraptor'' was capable of [[wing-assisted incline running]], as well as wing-assisted leaping and even ground-based launching.<ref name=Dececchi_etal_2016/>

Stephen Czerkas, Gregory S. Paul, and others have argued that the fact ''Microraptor'' could fly and yet is also very clearly a dromaeosaurid suggests that the [[Dromaeosauridae]], including later and larger species such as ''[[Deinonychus]]'', were secondarily flightless. The work of Xu and colleagues also suggested that the ancestors of dromaeosaurids were probably small, arboreal, and capable of [[Gliding flight|gliding]], although later discoveries of more primitive dromaeosaurids with short forelimbs unsuitable for gliding have cast doubt on this view.<ref name="Xuetal2003"/><ref name=Turneretal07>{{cite journal | last1 = Turner | first1 = Alan H. | last2 = Pol | first2 = Diego | last3 = Clarke | first3 = Julia A. | last4 = Erickson | first4 = Gregory M. | last5 = Norell | first5 = Mark | year = 2007 | title = A basal dromaeosaurid and size evolution preceding avian flight | journal = Science | volume = 317 | issue = 5843| pages = 1378–1381 | doi = 10.1126/science.1144066 | pmid = 17823350 | bibcode = 2007Sci...317.1378T | doi-access = free }}</ref> Work done on the question of flight ability in other paravians, however, showed that most of them probably would not have been able to achieve enough lift for powered flight, given their limited flight strokes and relatively smaller wings. These studies concluded that ''Microraptor'' probably evolved flight and its associated features (fused sternum, alula, etc.) independently of the ancestors of birds.<ref name=Dececchi_etal_2016/><ref>{{Cite journal|last1=Hartman|first1=Scott|last2=Mortimer|first2=Mickey|last3=Wahl|first3=William R.|last4=Lomax|first4=Dean R.|last5=Lippincott|first5=Jessica|last6=Lovelace|first6=David M.|date=2019-07-10|title=A new paravian dinosaur from the Late Jurassic of North America supports a late acquisition of avian flight|journal=PeerJ|language=en|volume=7|pages=e7247|doi=10.7717/peerj.7247|issn=2167-8359|pmc=6626525|pmid=31333906 |doi-access=free }}</ref><ref>{{Cite journal|last1=Pei|first1=Rui|last2=Pittman|first2=Michael|last3=Goloboff|first3=Pablo A.|last4=Dececchi|first4=T. Alexander|last5=Habib|first5=Michael B.|last6=Kaye|first6=Thomas G.|last7=Larsson|first7=Hans C.E.|last8=Norell|first8=Mark A.|last9=Brusatte|first9=Stephen L.|last10=Xu|first10=Xing|date=2020|title=Potential for Powered Flight Neared by Most Close Avialan Relatives, but Few Crossed Its Thresholds|url=|journal=Current Biology|volume=30|issue=20|language=en|pages=4033–4046.e8|doi=10.1016/j.cub.2020.06.105|pmid=32763170|doi-access=free|bibcode=2020CBio...30E4033P |hdl=11336/143103|hdl-access=free}}</ref><ref name=D20>{{cite journal |last1=Dececchi |first1=T. Alexander |last2=Larsson |first2=Hans C. E. |last3=Pittman |first3=Michael |last4=Habib |first4=Michael B. |title=High flyer or high fashion? A comparison of flight potential among small-bodied paravians |journal=Bulletin of the American Museum of Natural History |date=2020 |volume=440 |pages=295–320 |url=http://digitallibrary.amnh.org/bitstream/handle/2246/7237/440-11-dececchi_et_al.pdf}}</ref> In 2024, Kiat and O'Connor analyzed that Mesozoic birds and ''Microraptor'' had remex morphologies that are consistent with modern volant birds, while [[Anchiornithidae|anchiornithid]]s and ''[[Caudipteryx]]'' were secondarily flightless.<ref>{{cite journal |last1=Kiat |first1=Yosef |last2=O’Connor |first2=Jingmai K. |title=Functional constraints on the number and shape of flight feathers |journal=Proceedings of the National Academy of Sciences |date=20 February 2024 |volume=121 |issue=8 |pages=e2306639121 |doi=10.1073/pnas.2306639121 |pmid=38346196 |pmc=10895369 |bibcode=2024PNAS..12106639K |issn=0027-8424}}</ref>

===Hindwing posture===
[[File:Microraptor models.png|thumb|Wind tunnel experiments with different wing configurations]]
[[Sankar Chatterjee]] suggested in 2005 that, in order for ''Microraptor'' to [[Gliding flight|glide]] or fly, the forewings and hindwings must have been on different levels (as on a [[biplane]]) and not overlaid (as on a [[dragonfly]]), and that the latter posture would have been anatomically impossible. Using this biplane model, Chatterjee was able to calculate possible methods of gliding and determined that ''Microraptor'' most likely employed a ''[[phugoid]]'' style of gliding: launching itself from a perch, the animal would have swooped downward in a deep U-shaped curve and then lifted again to land on another tree. The feathers not directly employed in the biplane [[wing]] structure, like those on the [[tibia]] and the [[tail]], could have been used to control drag and alter the [[Airway (aviation)|flight path]], [[trajectory]], etc. The orientation of the hindwings would also have helped the animal control its gliding flight. Chatterjee also used computer [[algorithm]]s that test [[Flying and gliding animals|animal flight]] capacity to test whether or not ''Microraptor'' was capable of true, powered flight, as opposed to or in addition to passive gliding. The resulting data showed that ''Microraptor'' did have the requirements to sustain level powered flight, so it is theoretically possible that the animal flew, as opposed to gliding.<ref name="chatterjee2007">{{cite journal | last1 = Chatterjee | first1 = S. | last2 = Templin | first2 = R.J. | year = 2007 | title = Biplane wing planform and flight performance of the feathered dinosaur ''Microraptor gui'' | url = http://www.pnas.org/cgi/reprint/0609975104v1.pdf | journal = Proceedings of the National Academy of Sciences | volume = 104 | issue = 5| pages = 1576–1580 | doi=10.1073/pnas.0609975104 | pmid=17242354 | pmc=1780066| bibcode = 2007PNAS..104.1576C | doi-access = free }}</ref>

Some paleontologists have doubted the biplane hypothesis, and have proposed other configurations. A 2010 study by Alexander ''et al.'' described the construction of a lightweight three-dimensional physical model used to perform glide tests. Using several hindleg configurations for the model, they found that the biplane model, while not unreasonable, was structurally deficient and needed a heavy-headed weight distribution for stable gliding, which they deemed unlikely. The study indicated that a laterally abducted hindwing structure represented the most biologically and aerodynamically consistent configuration for ''Microraptor''.<ref name=alexanderetal2010>{{cite journal | last1 = Alexander | first1 = D.E. | last2 = Gong | first2 = E. | last3 = Martin | first3 = L.D. | last4 = Burnham | first4 = D.A. | last5 = Falk | first5 = A.R. | year = 2010 | title = Model tests of gliding with different hindwing configurations in the four-winged dromaeosaurid ''Microraptor gui'' | journal = Proceedings of the National Academy of Sciences, USA | volume = 107 | issue = 7| pages = 2972–2976 | doi = 10.1073/pnas.0911852107 | pmid = 20133792 | bibcode = 2010PNAS..107.2972A | pmc = 2840342 | doi-access = free }}</ref> A further analysis by Brougham and Brusatte, however, concluded that Alexander's model reconstruction was not consistent with all of the available data on ''Microraptor'' and argued that the study was insufficient for determining a likely flight pattern for ''Microraptor''. Brougham and Brusatte criticized the anatomy of the model used by Alexander and his team, noting that the hip anatomy was not consistent with other dromaeosaurs. In most dromaeosaurids, features of the hip bone prevent the legs from splaying horizontally; instead, they are locked in a vertical position below the body. Alexander's team used a specimen of ''Microraptor'' which was crushed flat to make their model, which Brougham and Brusatte argued did not reflect its actual anatomy.<ref>{{cite journal | last1 = Brusatte | first1 = Stephen L. | last2 = Brougham | first2 = Jason | year = 2010| title = Distorted ''Microraptor'' specimen is not ideal for understanding the origin of avian flight | journal = Proceedings of the National Academy of Sciences, USA | volume = 107| issue = 40| pages = E155| doi = 10.1073/pnas.1004977107 | pmid = 20864633 | bibcode = 2010PNAS..107E.155B| pmc = 2951411| doi-access = free }}</ref> Later in 2010, Alexander's team responded to these criticisms, noting that the related dromaeosaur ''[[Hesperonychus]]'', which is known from complete hip bones preserved in three dimensions, also shows hip sockets directed partially upward, possibly allowing the legs to splay more than in other dromaeosaurs.<ref>{{cite journal | last1 = Alexander | first1 = D.E. | last2 = Gong | first2 = E. | last3 = Martin | first3 = L.D. | last4 = Burnham | first4 = D.A. | last5 = Falk | first5 = A.R. | year = 2010 | title = Reply to Brougham and Brusatte: Overall anatomy confirms posture and flight model offers insight into the evolution of bird flight | journal = Proceedings of the National Academy of Sciences, USA | volume = 107| issue = 40| pages = E155| doi = 10.1073/pnas.1004977107 | pmid = 20864633 | bibcode = 2010PNAS..107E.155B | pmc = 2951411 | doi-access = free }}</ref> However, Hartman and colleagues suggested that ''Hesperonychus'' is not a dromaeosaur, but actually an [[Avialae|avialan]] close to modern [[bird]]s like ''[[Balaur bondoc]]'' based on phylogenetic analyses in 2019.<ref name=H19>{{Cite journal |last1=Hartman |first1=Scott |last2=Mortimer |first2=Mickey |last3=Wahl |first3=William R. |last4=Lomax |first4=Dean R. |last5=Lippincott |first5=Jessica |last6=Lovelace |first6=David M. |date=2019-07-10 |title=A new paravian dinosaur from the Late Jurassic of North America supports a late acquisition of avian flight |journal=PeerJ |language=en |volume=7 |pages=e7247 |doi=10.7717/peerj.7247 |issn=2167-8359 |pmc=6626525 |pmid=31333906 |doi-access=free }}</ref>

===Ground movement===
[[File:Microraptor by durbed.jpg|thumb|Restoration of two individuals by the ground]]
Due to the extent of the hindwings onto most of the animal's foot, many scientists have suggested that ''Microraptor'' would have been awkward during normal ground movement or running. The front wing feathers would also have hindered ''Microraptor'' when on the ground, due to the limited range of motion in the wrist and the extreme length of the wing feathers. A 2010 study by Corwin Sullivan and colleagues showed that, even with the wing folded as far as possible, the feathers would still have dragged along the ground if the arms were held in a neutral position, or extended forward as in a predatory strike. Only by keeping the wings elevated, or the upper arm extended fully backward, could ''Microraptor'' have avoided damaging the wing feathers. Therefore, it may have been anatomically impossible for ''Microraptor'' to have used its clawed forelimbs in capturing prey or manipulating objects.<ref name=sullivanetal2010>{{cite journal | last1 = Sullivan | first1 = C. | last2 = Hone | first2 = D.W.E. | last3 = Xu | first3 = X. | last4 = Zhang | first4 = F. | year = 2010 | title = The asymmetry of the carpal joint and the evolution of wing folding in maniraptoran theropod dinosaurs | journal = Proceedings of the Royal Society B | volume = 277 | issue = 1690| pages = 2027–2033 | doi = 10.1098/rspb.2009.2281 | pmid = 20200032 | pmc = 2880093 }}</ref>

===Implications===
[[File:Tetrapteryx.jpg|thumb|left|[[William Beebe]]'s hypothetical "''Tetrapteryx''" with four wings, 1915]]
The unique wing arrangement found in ''Microraptor'' raised the question of whether the evolution of flight in modern birds went through a four-winged stage, or whether four-winged gliders like ''Microraptor'' were an evolutionary side-branch that left no descendants. As early as 1915, [[Natural history|naturalist]] [[William Beebe]] had argued that the evolution of bird flight may have gone through a four-winged (or ''tetrapteryx'') stage.<ref name="beebe1915">{{cite journal | last1 = Beebe | first1 = C. W. A. | year = 1915 | title = Tetrapteryx stage in the ancestry of birds | journal = Zoologica | volume = 2 | pages = 38–52 }}</ref> Chatterjee and Templin did not take a strong stance on this possibility, noting that both a conventional interpretation and a tetrapteryx stage are equally possible. However, based on the presence of unusually long leg feathers in various feathered dinosaurs, ''[[Archaeopteryx]]'', and some modern birds such as raptors, as well as the discovery of further dinosaurs with long primary feathers on their feet (such as ''[[Pedopenna]]''), the authors argued that the current body of evidence, both from morphology and phylogeny, suggests that bird flight did shift at some point from shared limb dominance to front-limb dominance and that all modern birds may have evolved from four-winged ancestors, or at least ancestors with unusually long leg feathers relative to the modern configuration.<ref name="chatterjee2007"/>

===Feeding===
[[File:Microraptor cast in Horniman Museum.jpg|thumb|Cast in [[Horniman Museum]]]]
In 2010 researchers announced that further preparation of the type fossil of ''M. zhaoianus'' revealed preserved probable gut contents, and a full study on them was later published in 2022 by David Hone and colleagues. These consisted of the remains of a mammal, primarily a complete and articulated right foot (including all [[Tarsal bone|tarsals]], [[metatarsals]], and most of the [[phalanges]]) as well as the shafts of additional long bones and potentially other fragments. The foot skeleton is similar to those of ''[[Eomaia]]'' and ''[[Sinodelphys]]''. It corresponds to an animal with an estimated snout to vent length of {{cvt|80|mm}} and a mass of {{cvt|13|–|43|g}}. The unguals of the foot are less curved than in ''Eomaia'' or ''Sinodelphys'', indicating that the mammal could climb but less effectively than in the two latter genera and so was likely not arboreal but potentially scansorial.<ref name="Larsson et al. 2010"/><ref name="Hone22"/>

It is ambiguous whether the mammal had been predated upon or scavenged by the ''Microraptor'', although the lack of other definitive body parts consumed may suggest the low-muscle mass foot may have been eaten during a late stage of carcass consumption, possibly through scavenging. The find is a rare example of a theropod definitively consuming a Mesozoic mammal.<ref name="Larsson et al. 2010">Larsson, Hans, Hone, David, Dececchi, T. Alexander, Sullivan, Corwin, Xu, Xing. "THE WINGED NON-AVIAN DINOSAUR MICRORAPTOR FED ON MAMMALS: IMPLICATIONS FOR THE JEHOL BIOTA ECOSYSTEM" "Program and Abstracts. 70th Anniversary Meeting Society of Vertebrate Paleontology October 2010" 114A.</ref><ref name="Hone22">{{Cite journal |last1=Hone |first1=D. W. |last2=Dececchi |first2=T. A. |last3=Sullivan |first3=C. |last4=Xu |first4=X. |last5=Larsson |first5=H. C. |year=2022 |title=Generalist diet of ''Microraptor zhaoianus'' included mammals |journal=Journal of Vertebrate Paleontology |volume=43 |issue=e2144337 |at=e2144337 |doi=10.1080/02724634.2022.2144337|bibcode=2022JVPal..42E4337H |s2cid=255051527 |url=https://zenodo.org/record/7477141 }}</ref> The only other two examples are the indeterminate [[tyrannosauroid]] specimen GMV 2124 (also known as NGMC 2124) and the holotype of ''[[Huadanosaurus]]'', both of which are previously attributed to ''[[Sinosauropteryx]]''.<ref>{{Cite journal |last1=Qiu |first1=Rui |last2=Wang |first2=Xiaolin |last3=Jiang |first3=Shunxing |last4=Meng |first4=Jin |last5=Zhou |first5=Zhonghe |date=2025-02-22 |title=Two new compsognathid-like theropods show diversified predation strategies in theropod dinosaurs |journal=National Science Review |volume=12 |issue=5 |pages=nwaf068 |language=en |doi=10.1093/nsr/nwaf068 |issn=2095-5138|doi-access=free |pmid=40191255 |pmc=11970238 }}</ref>

In the December 6, 2011 issue of ''Proceedings of the National Academy of Sciences'', Jingmai O'Connor and coauthors described a specimen of ''Microraptor gui'' containing bones of an arboreal [[enantiornithean]] bird in its abdomen, specifically a partial wing and feet. Their position implies the bird was swallowed whole and head-first, which the authors interpreted as implying that the ''Microraptor'' had caught and consumed the bird in the trees, rather than scavenging it.<ref>{{cite journal |author1=Jingmai O'Connor |author2=Zhonghe Zhou |author3=Xing Xu |name-list-style=amp |year=2011 |title=Additional specimen of ''Microraptor'' provides unique evidence of dinosaurs preying on birds |journal=Proceedings of the National Academy of Sciences of the United States of America |volume=108 |issue=49 |pages=19662–19665 |doi=10.1073/pnas.1117727108 |pmid=22106278 |pmc=3241752|bibcode=2011PNAS..10819662O |doi-access=free }}</ref>

In 2013 researchers announced that they had found fish scales in the abdominal cavity of another ''M. gui'' specimen.<ref name=Xing13>{{cite journal |author=Lida Xing|year=2013 |title=Piscivory in the feathered dinosaur ''Microraptor'' |journal=Evolution|doi=10.1111/evo.12119|display-authors=etal |volume=67 |issue=8 |pages=2441–2445 |pmid=23888864|s2cid=34471616 |doi-access=free }}</ref> The authors contradicted the prior suggestion that ''M. gui'' hunted only in an arboreal environment, proposing that it was also an adept hunter of fish as well. They further argued that the specimen showed a probable adaptation to a fish-eating diet, pointing to the first three teeth of the mandible being inclined anterodorsally, a characteristic often associated with piscivory.<ref name=Xing13/> They concluded that ''Microraptor'' was an opportunistic feeder, hunting the most common prey in both arboreal and aquatic habitats.<ref name=Xing13/>

Both of these studies regarded each gut contents as instances of predation. However, Hone and colleagues (2022) questioned the reliability of these interpretations and wrote that both could just as equally be attributed to scavenging. Further, they argued against ''Microraptor'' being a specialist in either or both arboreal or aquatic hunting, citing the broad range of vertebrate gut contents (i.e. fish, mammals, lizards, birds) as evidence for a generalist hunting strategy, and that neither required that ''Microraptor'' being a specialist for hunting in either habitats.<ref name="Hone22"/>

In 2019, a new genus of [[scleroglossa]]n [[lizard]] (''[[Indrasaurus]]'') was described from a specimen found in the stomach of a ''Microraptor''. The ''Microraptor'' apparently swallowed its prey head first, a behavior typical of modern [[Carnivore|carnivorous]] [[bird]]s and lizards. The ''Indrasaurus'' bones lacked marked pitting and scarring, indicating that the ''Microraptor'' died shortly after eating the lizard and before significant digestion had occurred.<ref name=":0">{{Cite journal|last1=Zhou|first1=Zhonghe|last2=Zhang|first2=Xiaomei|last3=Wang|first3=Yan|last4=Wang|first4=Xiaoli|last5=Dong|first5=Liping|last6=Zheng|first6=Xiaoting|last7=O’Connor|first7=Jingmai|date=2019-07-11|title=Microraptor with Ingested Lizard Suggests Non-specialized Digestive Function|journal=Current Biology|volume=29|language=en|issue=14|pages=2423–2429.e2|doi=10.1016/j.cub.2019.06.020|issn=0960-9822|pmid=31303494|doi-access=free|bibcode=2019CBio...29E2423O }}</ref>

Unlike its fellow [[Paraves|paravian]] ''[[Anchiornis]]'', ''Microraptor'' has never been found with [[Pellet (ornithology)|gastric pellets]], despite the existence of four ''Microraptor'' specimens that preserve stomach contents. This suggests that ''Microraptor'' passed indigestible fur, feathers, and bits of bone in its droppings instead of producing pellets.<ref name=":0" />

Based on the size of the [[Sclerotic ring|scleral ring]] of the eye, it has been suggested ''Microraptor'' hunted at night.<ref>{{cite journal | title=Nocturnality in dinosaurs inferred from scleral ring and orbit morphology|vauthors=Schmitz L, Motani R | journal=Science| year=2011| doi=10.1126/science.1200043| pmid=21493820| volume=332 | issue=6030 | pages=705–8| bibcode=2011Sci...332..705S|s2cid=33253407 }}</ref> However, the discovery of iridescent plumage in ''Microraptor'' has cast doubt on this conclusion, as no modern birds that have iridescent plumage are known to be nocturnal.<ref name="iridescence"/>

==See also==
{{Portal|Dinosaurs}}
* [[Dinosaur coloration]]
* [[Timeline of dromaeosaurid research]]

==Notes==
{{Notelist}}

==References==
{{Reflist|2}}

==External links==
{{Wikispecies|Microraptor}}
*[[Dromaeosauridae#Relationship with birds|Dromaeosauridae, ''Relationship with birds'']]
*[https://web.archive.org/web/20040306034207/http://www.indyrad.iupui.edu/public/jrafert/Filipovic/newfeather/Microraptor-gui-%28Cryptovol.jpg A model of ''Microraptor''/Cryptovolans pauli by Boban Filipovic]
*Jacqui Hayes: [http://www.cosmosmagazine.com/node/984 Bird wings evolved from biplane dinosaurs] {{Webarchive|url=https://web.archive.org/web/20070127002632/http://www.cosmosmagazine.com/node/984 |date=2007-01-27 }} COSMOS magazine
*[https://www.pbs.org/wgbh/nova/microraptor/ The Four-Winged Dinosaur] - PBS website for the ''Nova'' documentary
*NewScientist [https://www.newscientist.com/articleimages/dn21552/1-microraptors-glossy-black-feather-coat-reconstructed.html Microraptor's glossy black feather coat reconstructed]
*[https://web.archive.org/web/20130618224030/http://phenomena.nationalgeographic.com/2012/03/08/a-shiny-dinosaur-four-winged-microraptor-gets-colour-and-gloss/ nationalgeographic.com 2012-03-08 Ed Yong, A shiny dinosaur four-winged Microraptor gets color and gloss]
*[https://web.archive.org/web/20130123100759/http://phenomena.nationalgeographic.com/2008/10/08/microraptor-the-dinosaur-that-flew-like-a-biplane/ nationalgeographic.com 2008-10-08 Ed Yong, Microraptor–the dinosaur that flew like a biplane]

{{Dromaeosauridae}}
{{Taxonbar|from=Q310537}}

[[Category:Microraptoria]]
[[Category:Dinosaur genera]]
[[Category:Aptian dinosaurs]]
[[Category:Jiufotang Formation]]
[[Category:Taxa named by Xu Xing]]
[[Category:Fossil taxa described in 2000]]
[[Category:Dinosaurs of China]]
[[Category:Feathered dinosaurs]]