Microraptor (Greek, μικρός,mīkros: "small";Latin,raptor: "one who seizes") is agenus of small, four-wingeddromaeosauriddinosaurs. Numerous well-preservedfossil specimens have been recovered fromLiaoning,China. They date from the earlyCretaceousJiufotang Formation (Aptian stage), 125 to 120 millionyears ago. Three species have been named (M. zhaoianus,M. gui, andM. hanqingi), though further study has suggested that all of them represent variation in a single species, which is properly calledM. zhaoianus.Cryptovolans, initially described as another four-winged dinosaur, is usually considered to be a synonym ofMicroraptor.^[2]

Microraptor Temporal range:Early Cretaceous,120 Ma PreꞒ Ꞓ O S D C P T J K Pg N ↓
Fossil specimen, with white arrows pointing at preserved feathers
Scientific classification
Domain:	Eukaryota
Kingdom:	Animalia
Phylum:	Chordata
Clade:	Dinosauria
Clade:	Saurischia
Clade:	Theropoda
Family:	†Dromaeosauridae
Clade:	†Microraptoria
Genus:	†Microraptor Xuet al., 2000
Type species
†Microraptor zhaoianus Xuet al., 2000
Otherspecies
†M. guiXuet al., 2003 †M. hanqingiGonget al., 2012
Synonyms
CryptovolansCzerkaset al., 2002 "Tetrapterornis"Miller, 2004 (nomen nudum)[1]

LikeArchaeopteryx, well-preserved fossils ofMicroraptor provide important evidence about the evolutionary relationship betweenbirds and earlier dinosaurs.Microraptor had longpennaceous feathers that formed aerodynamic surfaces on the arms and tail but also on the legs. This led paleontologistXu Xing in 2003 to describe the first specimen to preserve this feature as a "four-winged dinosaur" and to speculate that it may haveglided using all four limbs for lift. Subsequent studies have suggested thatMicroraptor was capable of powered flight as well.

Microraptor was among the most abundant non-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.^[3] One specimen in particular shows evidence of active primary feathermoulting, which is one of the few known fossil evidence of such behavior among pennaraptoran dinosaurs.^[4]

The initial naming ofMicroraptor 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 forsale. After the forgery was revealed byXu Xing ofBeijing'sInstitute of Vertebrate Paleontology and Paleoanthropology,Storrs L. Olson, curator of birds in theNational Museum of Natural History of theSmithsonian Institution, published a description of the Microraptor's tail in an obscure journal, giving it the nameArchaeoraptor liaoningensis in an attempt to remove the name from the paleornithological record by assigning it to the part least likely to be a bird.^[5] 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 nameMicroraptor zhaoianus.^[6]

Since the two names designate the same individual as thetype specimen,Microraptor zhaoianus would have been ajunior objective synonym ofArchaeoraptor liaoningensis and the latter, if valid, would have had priority under theInternational 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 alectotype, before an actual type species was formally erected.^[7] A similar situation arose withTyrannosaurus rex andManospondylus gigas, in which the former became anomen protectum and the latter anomen oblitum due to revisions in the ICZN rules that took place on December 31, 1999.^[8] 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" anomen vanum (as it was improperly described) and the junior synonymMicroraptor anomen protectum (as it's been used in more published works than "Archaeoraptor" and was properly described).^[9]

The first specimen referred toMicroraptor represented a small individual and included faint feather remnants, but was otherwise not well preserved and lacked a skull.In 2002Mark Norell et al. described another specimen, BPM 1 3-13, which they did not name or refer to an existing species.^[10] Later that yearStephen Czerkas et al. named the specimenCryptovolans pauli, and referred two additional specimens (the first to show well-preserved feathers) to this species. The generic name was derived from Greekkryptos, "hidden", andLatinvolans, "flying". Thespecific name,pauli, honorspaleontologistGregory S. Paul, who had long proposed that dromaeosaurids evolved from flying ancestors.^[11]

Thetype specimens ofC. pauli were collected from theJiufotang Formation, dating from the earlyAlbian and now belong to the collection of the Paleontology Museum of Beipiao, inLiaoning, China. They are referred to by the inventory numbers LPM 0200, theholotype; LPM 0201, its counterslab (slab and counterslab together represent the earlier BPM 1 3-13); and theparatype LPM 0159, a smaller skeleton. Both individuals are preserved as articulated compression fossils; they are reasonably complete but partially damaged.^[11]

Czerkaset al. (2002) diagnosed the genus on the basis of having primary feathers (which in the authors' opinion made it abird), a co-ossified sternum, a tail consisting of 28 to 30 vertebrae and a third finger with a short phalanx III-3.^[11] 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 genusMicroraptor, which was first described earlier thanCryptovolans.^[12] However, BPM 1 3-13 has a longer tail, proportionately, than otherMicroraptor specimens that had been described by 2002, which have 24 to 26 tail vertebrae.^[10]

Subsequent studies (and more specimens ofMicroraptor) have shown that the features used to distinguishCryptovolans 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 singleMicroraptor species, making the nameCryptovolans pauli andMicroraptor gui junior synonyms ofMicroraptor zhaoianus.^[2] Many other researchers, including Alan Feduccia and Tom Holtz, have since supported its synonymy.^[13][14]M. gui has been accepted as a distinct species with the specimen reported in 2013 being distinguishable from the type specimen ofM. zhaoianus.^[15]

A new specimen ofMicroraptor, 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 knownMicroraptor 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 oftaphonomic distortion.^[16][17]

Numerous further specimens likely belonging toMicroraptor have been uncovered, all from the Shangheshou Bed of theJiufotang Formation in Liaoning, China. In fact,Microraptor is the most abundant non-avialan dinosaur fossil type found in this formation.^[18] In 2010, it was reported that there were over 300 undescribed specimens attributable toMicroraptor or its close relatives among the collections of several Chinese museums, though many had been altered or composited by private fossil collectors.^[3]

Norellet 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.^[19]

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 bookFeathered Dinosaurs and the Origin of Flight.^[11] In his discussion ofCryptovolans 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".^[11] Czerkas also denounced Norell for failing to conclude thatdromaeosaurs are birds, accusing him of succumbing to "...the blinding influences of preconceived ideas."^[11] Thecrown group definition of Aves, as a subset ofAvialae, 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.^[19]

Czerkas's interpretation of the hindleg feathers noted by Norell proved to be incorrect the following year when additional specimens ofMicroraptor 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, theInstitute of Vertebrate Paleontology and Paleoanthropology. Xu also considered these specimens, most of which had hindwings and proportional differences from the originalMicroraptor specimen, to be a new species, which he namedMicroraptor gui. However, Senter also questioned this classification, noting that as withCryptovolans, most of the differences appeared to correspond with size, and likely age differences.^[2] Two further specimens, classified asM. zhaoianus in 2002 (M. gui had not yet been named), have also been described by Hwang and colleagues.^[20]

Czerkas also believed that the animal may have been able to fly better thanArchaeopteryx, the animal usually referred to as the earliest known bird. He cited the fused sternum and asymmetrical feathers, and argued thatMicroraptor has modern bird features that make it more derived thanArchaeopteryx. Czerkas cited the fact that this possibly volant animal is also very clearly a dromaeosaurid to suggest that theDromaeosauridae might actually be a basal bird group, and that later, larger, species such asDeinonychus 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 Xuet al. (2003) suggested that basal dromaeosaurs were probably small, arboreal, and could glide.^[21] The work of Turneret 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 cm long and 600–700 g in mass).^[22]

Microraptor was among thesmallest-known non-avian dinosaurs, with the holotype ofM. gui measuring 77 centimetres (2.53 ft) in length, 88–94 centimetres (2.89–3.08 ft) in wingspan and weighing 0.5–1.4 kilograms (1.1–3.1 lb).^[23][24][25] There are larger specimens which would have measured at least 80 centimetres (2.6 ft) in length, more than 99 centimetres (3.25 ft) in wingspan and weighed 1.25–1.88 kilograms (2.8–4.1 lb).^[25][a] Aside from their extremely small size,Microraptor were among the first non-avialan dinosaurs discovered with the impressions of feathers and wings. Seven specimens ofM. 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). Xuet al. (2003) compared the longer plumes onMicroraptor's head to those of thePhilippine eagle. Bands of dark and light present on some specimens may indicate color patterns present in life,^[20] though at least some individuals almost certainly possessed an iridescent black coloration.^[16]

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 inMicroraptor, 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 primitivetroodontids.Microraptor is particularly similar to the basal troodontidSinovenator; in their 2002 description of twoM. zhaoianus specimens, Hwanget al. note that this is not particularly surprising, given that bothMicroraptor andSinovenator are very primitive members of two closely related groups, and both are close to thedeinonychosaurian split between dromaeosaurids and troodontids.^[20]

In March 2012, Quanguo Liet al. determined the plumage coloration ofMicroraptor based on the new specimen BMNHC PH881, which also showed several other features previously unknown inMicroraptor. By analyzing the fossilized melanosomes (pigment cells) in the fossil withscanning electron microscope techniques, the researchers compared their arrangements to those of modern birds. InMicroraptor, 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 modernstarling, and indicatediridescence in the plumage ofMicroraptor. 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.^[16][17]

The cladogram below follows a 2012 analysis by paleontologists Phil Senter, James I. Kirkland, Donald D. DeBlieux, Scott Madsen and Natalie Toth.^[27]

In a 2024 paper which reported the smallest known juvenile specimen ofMicroraptor, Wang and Pei includedmicroraptorians andeudromaeosaurians within a new clade Serraraptoria.^[28]

Microraptor had fourwings, one on each of its forelimbs and hindlimbs, somewhat resembling one possible arrangement of the quartet of flight surfaces on atandem wing aircraft of today. It had longpennaceous feathers on arms and hands 10–20 cm long (3.9–7.9 in) with legs and feet 11–15 cm long (4.3–5.9 in). The long feathers on the legs ofMicroraptor were true flight feathers as seen in modernbirds, 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, withflight feathers 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.^[29]

It was originally thought thatMicroraptor was aglider, and probably lived mainly in trees, because the hindwings anchored to the feet ofMicroraptor would have hindered their ability to run on the ground.^[30] 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.^[31] In their 2007 study, Chatterjee and Templin tested this hypothesis as well, and found that the combined wing surface ofMicroraptor was too narrow to successfully parachute to the ground without injury from any significant height. However, the authors did leave open the possibility thatMicroraptor could have parachuted short distances, as between closely spaced tree branches.^[23][31] Wind tunnel experiments have demonstrated that sustaining a high-lift coefficient at the expense of high drag was likely the most efficient strategy forMicroraptor when gliding between low elevations.Microraptor did not require a sophisticated, 'modern' wing morphology to be an effective glider.^[32] However, the idea thatMicroraptor 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.^[33][26]

Describing specimens originally referenced as a distinctive species (Cryptovolans pauli), paleontologist Stephen Czerkas arguedMicroraptor may have been a powered flier, and indeed possibly a better flyer thanArchaeopteryx. He noted that theMicroraptor'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 thatMicroraptor 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 thevertebral column until relatively advanced avialans like theenantiornithes appeared.^[34] However, other scientists have argued that the shoulder girdle in someparavian theropods, includingMicroraptor, 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 apropatagium 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 analula, much like a "thumb-like" form ofleading edge slot, may indicate thatMicroraptor was capable of true, powered flight.^[35]

Other studies have demonstrated that the wings ofMicroraptor 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 thatMicroraptor was capable ofwing-assisted incline running, as well as wing-assisted leaping and even ground-based launching.^[26]

Stephen Czerkas, Gregory S. Paul, and others have argued that the factMicroraptor could fly and yet is also very clearly a dromaeosaurid suggests that theDromaeosauridae, including later and larger species such asDeinonychus, were secondarily flightless. The work of Xu and colleagues also suggested that the ancestors of dromaeosaurids were probably small, arboreal, and capable ofgliding, although later discoveries of more primitive dromaeosaurids with short forelimbs unsuitable for gliding have cast doubt on this view.^[30][22] 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 thatMicroraptor probably evolved flight and its associated features (fused sternum, alula, etc.) independently of the ancestors of birds.^{[26][36][37][25]} In 2024, Kiat and O'Connor analyzed that Mesozoic birds andMicroraptor had remex morphologies that are consistent with modern volant birds, whileanchiornithids andCaudipteryx were secondarily flightless.^[38]

Sankar Chatterjee suggested in 2005 that, in order forMicroraptor toglide or fly, the forewings and hindwings must have been on different levels (as on abiplane) and not overlaid (as on adragonfly), 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 thatMicroraptor most likely employed aphugoid 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 biplanewing structure, like those on thetibia and thetail, could have been used to control drag and alter theflight path,trajectory, etc. The orientation of the hindwings would also have helped the animal control its gliding flight. Chatterjee also used computeralgorithms that testanimal flight capacity to test whether or notMicroraptor was capable of true, powered flight, as opposed to or in addition to passive gliding. The resulting data showed thatMicroraptor did have the requirements to sustain level powered flight, so it is theoretically possible that the animal flew, as opposed to gliding.^[23]

Some paleontologists have doubted the biplane hypothesis, and have proposed other configurations. A 2010 study by Alexanderet 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 forMicroraptor.^[3] A further analysis by Brougham and Brusatte, however, concluded that Alexander's model reconstruction was not consistent with all of the available data onMicroraptor and argued that the study was insufficient for determining a likely flight pattern forMicroraptor. 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 ofMicroraptor which was crushed flat to make their model, which Brougham and Brusatte argued did not reflect its actual anatomy.^[39] Later in 2010, Alexander's team responded to these criticisms, noting that the related dromaeosaurHesperonychus, 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.^[40] However, Hartman and colleagues suggested thatHesperonychus is not a dromaeosaur, but actually anavialan close to modernbirds likeBalaur bondoc based on phylogenetic analyses in 2019.^[41]

Due to the extent of the hindwings onto most of the animal's foot, many scientists have suggested thatMicroraptor would have been awkward during normal ground movement or running. The front wing feathers would also have hinderedMicroraptor 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, couldMicroraptor have avoided damaging the wing feathers. Therefore, it may have been anatomically impossible forMicroraptor to have used its clawed forelimbs in capturing prey or manipulating objects.^[42]

The unique wing arrangement found inMicroraptor raised the question of whether the evolution of flight in modern birds went through a four-winged stage, or whether four-winged gliders likeMicroraptor were an evolutionary side-branch that left no descendants. As early as 1915,naturalistWilliam Beebe had argued that the evolution of bird flight may have gone through a four-winged (ortetrapteryx) stage.^[43] 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 asPedopenna), 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.^[23]

In 2010 researchers announced that further preparation of the type fossil ofM. 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 alltarsals,metatarsals, and most of thephalanges) as well as the shafts of additional long bones and potentially other fragments. The foot skeleton is similar to those ofEomaia andSinodelphys. It corresponds to an animal with an estimated snout to vent length of 80 mm (3.1 in) and a mass of 13–43 g (0.46–1.52 oz). The unguals of the foot are less curved than inEomaia orSinodelphys, indicating that the mammal could climb but less effectively than in the two latter genera and so was likely not arboreal but potentially scansorial.^[44][45]

It is ambiguous whether the mammal had been predated upon or scavenged by theMicroraptor, 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.^[44][45] The only other two examples are the indeterminatetyrannosauroid specimen GMV 2124 (also known as NGMC 2124) and the holotype ofHuadanosaurus, both of which are previously attributed toSinosauropteryx.^[46]

In the December 6, 2011 issue ofProceedings of the National Academy of Sciences, Jingmai O'Connor and coauthors described a specimen ofMicroraptor gui containing bones of an arborealenantiornithean 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 theMicroraptor had caught and consumed the bird in the trees, rather than scavenging it.^[47]

In 2013 researchers announced that they had found fish scales in the abdominal cavity of anotherM. gui specimen.^[15] The authors contradicted the prior suggestion thatM. 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.^[15] They concluded thatMicroraptor was an opportunistic feeder, hunting the most common prey in both arboreal and aquatic habitats.^[15]

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 againstMicroraptor 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 thatMicroraptor being a specialist for hunting in either habitats.^[45]

In 2019, a new genus ofscleroglossanlizard (Indrasaurus) was described from a specimen found in the stomach of aMicroraptor. TheMicroraptor apparently swallowed its prey head first, a behavior typical of moderncarnivorousbirds and lizards. TheIndrasaurus bones lacked marked pitting and scarring, indicating that theMicroraptor died shortly after eating the lizard and before significant digestion had occurred.^[48]

Unlike its fellowparavianAnchiornis,Microraptor has never been found withgastric pellets, despite the existence of fourMicroraptor specimens that preserve stomach contents. This suggests thatMicroraptor passed indigestible fur, feathers, and bits of bone in its droppings instead of producing pellets.^[48]

Based on the size of thescleral ring of the eye, it has been suggestedMicroraptor hunted at night.^[49] However, the discovery of iridescent plumage inMicroraptor has cast doubt on this conclusion, as no modern birds that have iridescent plumage are known to be nocturnal.^[16]

• Dinosaur coloration
• Timeline of dromaeosaurid research

• Dromaeosauridae,Relationship with birds
• A model ofMicroraptor/Cryptovolans pauli by Boban Filipovic
• Jacqui Hayes:Bird wings evolved from biplane dinosaursArchived 2007-01-27 at theWayback Machine COSMOS magazine
• The Four-Winged Dinosaur - PBS website for theNova documentary
• NewScientistMicroraptor's glossy black feather coat reconstructed
• nationalgeographic.com 2012-03-08 Ed Yong, A shiny dinosaur four-winged Microraptor gets color and gloss
• nationalgeographic.com 2008-10-08 Ed Yong, Microraptor–the dinosaur that flew like a biplane