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67-580: Dromaeosauridae ( / ˌ d r ɒ m i . ə ˈ s ɔːr ɪ d iː / ) is a family of feathered coelurosaurian theropod dinosaurs . They were generally small to medium-sized feathered carnivores that flourished in the Cretaceous Period . The name Dromaeosauridae means 'running lizards', from Greek δρομαῖος ( dromaîos ), meaning 'running at full speed', 'swift', and σαῦρος ( saûros ), meaning 'lizard'. In informal usage, they are often called raptors (after Velociraptor ),
134-608: A dromaeosaurid , was too heavy to fly but still had wings with feathers required for flying, which suggests its ancestors had the ability for aerial locomotion. Other groups, like the Oviraptorosauria who had a tail with a tail fan of feathers with caudal anatomy resembling a pygostyle , are not known to have been capable of flight, but some scientists, such as Gregory S. Paul , have suggested that they could be descended from ancestors which flew. Paul has gone as far as to propose that Therizinosauria , Alvarezsauroidea , and
201-407: A trochanteric crest . An elongated, backwards-pointing pubic bone is present in therizinosauroids, dromaeosaurids, avialans, and the basal troodontid Sinovenator , which suggests that the propubic condition in advanced troodontids and oviraptorosaurs is a reversal. Turner et al. (2007) named seven synapomorphies that diagnose Maniraptora. Modern pennaceous feathers and remiges are known in
268-493: A 2001 paper. Their proposed definition for the group was "the clade stemming from the first panavian with ... remiges and rectrices , that is, enlarged, stiff-shafted, closed-vaned (= barbules bearing hooked distal pennulae), pennaceous feathers arising from the distal forelimbs and tail". Ancestral morphology relating to pennaceous feathers suggests that basal species of Pennaraptora were capable of scansorial locomotion and gliding, and further evolution of said adaptation within
335-708: A 2015 analysis by DePalma et al. using updated data from the Theropod Working Group. Rahonavis Buitreraptor Unenlagia Sinornithosaurus [REDACTED] Microraptor [REDACTED] NGMC 91 [REDACTED] Bambiraptor [REDACTED] Tianyuraptor Adasaurus Tsaagan Saurornitholestes Velociraptor [REDACTED] Deinonychus [REDACTED] Atrociraptor [REDACTED] Achillobator [REDACTED] Utahraptor [REDACTED] Dakotaraptor [REDACTED] Dromaeosaurus [REDACTED] Another cladogram constructed below follows
402-500: A feathered bird-like predator) is a clade within Maniraptora, defined as the most recent common ancestor of Oviraptor philoceratops , Deinonychus antirrhopus , and Passer domesticus (the house sparrow), and all descendants thereof, by Foth et al. , 2014. The clade "Aviremigia" was conditionally proposed along with several other apomorphy -based clades relating to birds by Jacques Gauthier and Kevin de Queiroz in
469-401: A flying ancestor for dromaeosaurids are sometimes called "Birds Came First" (BCF). George Olshevsky is usually credited as the first author of BCF. In his own work, Gregory S. Paul pointed out numerous features of the dromaeosaurid skeleton that he interpreted as evidence that the entire group had evolved from flying, dinosaurian ancestors, perhaps an animal like Archaeopteryx . In that case,
536-482: A great deal of study, and hypotheses about that relationship have changed as large amounts of new evidence became available. As late as 2001, Mark Norell and colleagues analyzed a large survey of coelurosaur fossils and produced the tentative result that dromaeosaurids were most closely related to birds, with troodontids as a more distant outgroup. They even suggested that Dromaeosauridae could be paraphyletic relative to Avialae. In 2002, Hwang and colleagues utilized
603-514: A group of bizarre creatures with long fingers and necks, a large number of small teeth, and possible semiaquatic habits. Another enigmatic group, Unenlagiinae, is the most poorly supported subfamily of dromaeosaurids and it is possible that some or all of its members belong outside of Dromaeosauridae. The larger, ground-dwelling members like Buitreraptor and Unenlagia show strong flight adaptations, although they were probably too large to 'take off'. One possible member of this group, Rahonavis ,
670-554: A lack of widespread consensus within the scientific community for extended periods. The continual publication of new data and diverse opinions plays a crucial role in facilitating adjustments and ultimately reaching a consensus over time. The naming of families is codified by various international bodies using the following suffixes: The taxonomic term familia was first used by French botanist Pierre Magnol in his Prodromus historiae generalis plantarum, in quo familiae plantarum per tabulas disponuntur (1689) where he called
737-418: A large, recurved claw on the second toe. Their tails were slender, with long, low, vertebrae lacking transverse process and neural spines after the 14th caudal vertebra. Ossified uncinate processes of ribs have been identified in several dromaeosaurids. Like other theropods, dromaeosaurids were bipedal; that is, they walked on their hind legs. However, whereas most theropods walked with three toes contacting
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#1732780925037804-503: A long, backwards-pointed pubis and short ischia were present in Scansoriopteryx , a scansoriopterygid. The authors considered it to be more primitive than true theropods, and hypothesized that maniraptorans may have branched off from theropods at a very early point, or may even have descended from pre-theropod dinosaurs. Zhang et al. , in describing the closely related or conspecific specimen Epidendrosaurus (now considered
871-450: A number of discoveries made during the first decade of the 21st century, as well as re-evaluation of older evidence, began to suggest that maniraptorans were a primarily omnivorous group, including a number of sub-groups that ate mainly plants, insects, or other food sources besides meat. Additionally, phylogenetic studies of maniraptoran relationships began to more consistently show that herbivorous or omnivorous groups were spread throughout
938-471: A primitive palatine , unreversed hallux , and hyper-extendable second toe. Their phylogenetic analysis produced the controversial result that Confuciusornis was closer to Microraptor than to Archaeopteryx , making the Avialae a paraphyletic taxon. They also suggested that the ancestral paravian was able to fly or glide, and that the dromaeosaurids and troodontids were secondarily flightless (or had lost
1005-517: A revised definition of the sub-group containing Microraptor to ensure that it would fall within Dromaeosauridae, and erected the subfamily Microraptorinae, attributing it to Senter et al. , though this usage has only appeared on his online TaxonSearch database and has not been formally published. The extensive cladistic analysis conducted by Turner et al. (2012) further supported the monophyly of Dromaeosauridae. The cladogram below follows
1072-482: A synonym of Scansoriopteryx ), did not report any of the primitive traits mentioned by Czerkas and Yuan, but did find that the shoulder blade of Epidendrosaurus appeared primitive. Despite this, they placed Epidendrosaurus firmly within Maniraptora due to a number of synapomorphies. Scientists traditionally assumed that maniraptorans were ancestrally hypercarnivorous , that is, that most non-avialan species primarily ate and hunted only other vertebrates . However,
1139-616: A tail-spanning fan, both of which are unexpected traits that may offer an understanding of the integument of large dromaeosaurids. Dakotaraptor is an even larger dromaeosaurid species with evidence of feathers, albeit indirect in the form of quill knobs, though the taxon is considered as chimeara by other researchers as even the dinosaurian elements with supposed traits diagnostic for dromaeosaurs also referrable to caenagnathids and ornithomimosaurians . Dromaeosaurids share many features with early birds (clade Avialae or Aves ). The precise nature of their relationship to birds has undergone
1206-542: A term popularized by the film Jurassic Park ; several genera include the term "raptor" directly in their name, and popular culture has come to emphasize their bird-like appearance and speculated bird-like behavior. Dromaeosaurid fossils have been found across the globe in North America , Europe , Africa , Asia and South America , with some fossils giving credence to the possibility that they inhabited Australia as well. The earliest body fossils are known from
1273-580: Is a large body of evidence showing that dromaeosaurids were covered in feathers . Some dromaeosaurid fossils preserve long, pennaceous feathers on the hands and arms ( remiges ) and tail ( rectrices ), as well as shorter, down-like feathers covering the body. Other fossils, which do not preserve actual impressions of feathers, still preserve the associated bumps on the forearm bones where long wing feathers would have attached in life. Overall, this feather pattern looks very much like Archaeopteryx . The first known dromaeosaurid with definitive evidence of feathers
1340-499: Is commonly referred to as the "walnut family". The delineation of what constitutes a family— or whether a described family should be acknowledged— is established and decided upon by active taxonomists . There are not strict regulations for outlining or acknowledging a family, yet in the realm of plants, these classifications often rely on both the vegetative and reproductive characteristics of plant species. Taxonomists frequently hold varying perspectives on these descriptions, leading to
1407-554: Is curved horizontally in a long S-shape. This suggests that, in life, the tail could bend from side to side with a substantial degree of flexibility. It has been proposed that this tail was used as a stabilizer or counterweight while running or in the air; in Microraptor , an elongate diamond-shaped fan of feathers is preserved on the end of the tail. This may have been used as an aerodynamic stabilizer and rudder during gliding or powered flight (see "Flight and gliding" below). There
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#17327809250371474-485: Is one of the eight major hierarchical taxonomic ranks in Linnaean taxonomy . It is classified between order and genus . A family may be divided into subfamilies , which are intermediate ranks between the ranks of family and genus. The official family names are Latin in origin; however, popular names are often used: for example, walnut trees and hickory trees belong to the family Juglandaceae , but that family
1541-533: Is very small, with well-developed wings that show evidence of quill knobs (the attachment points for flight feathers) and it is very likely that it could fly. The next most primitive clade of dromaeosaurids is the Microraptoria. This group includes many of the smallest dromaeosaurids, which show adaptations for living in trees. All known dromaeosaurid skin impressions hail from this group and all show an extensive covering of feathers and well-developed wings. Like
1608-505: The Genera Plantarum of George Bentham and Joseph Dalton Hooker this word ordo was used for what now is given the rank of family. Families serve as valuable units for evolutionary, paleontological, and genetic studies due to their relatively greater stability compared to lower taxonomic levels like genera and species. Maniraptora Maniraptora is a clade of coelurosaurian dinosaurs which includes
1675-602: The birds and the non-avian dinosaurs that were more closely related to them than to Ornithomimus velox . It contains the major subgroups Avialae , Dromaeosauridae , Troodontidae , Oviraptorosauria , and Therizinosauria . Ornitholestes and the Alvarezsauroidea are also often included. Together with the next closest sister group, the Ornithomimosauria , Maniraptora comprises the more inclusive clade Maniraptoriformes . Maniraptorans first appear in
1742-465: The scansoriopterygids , Pedopenna , and Yixianosaurus . In 1993, Perle and colleagues coined the name Metornithes to include alvarezsaurids and modern birds, which the researchers believed were members of the Avialae. This group was defined as a clade by Luis Chiappe in 1995 as the last common ancestor of Mononykus and modern birds, and all its descendants. Pennaraptora (Latin penna "bird feather" + raptor "thief", from rapere "snatch";
1809-636: The unenlagiines ( Austroraptor , which measured 5–6 m (16–20 ft) long). A possible third lineage of giant dromaeosaurids is represented by isolated teeth found on the Isle of Wight , England . The teeth belong to an animal the size of the dromaeosaurine Utahraptor , but they appear to belong to velociraptorines, judging by the shape of the teeth. The distinctive dromaeosaurid body plan helped to rekindle theories that dinosaurs may have been active, fast, and closely related to birds. Robert Bakker 's illustration for John Ostrom 's 1969 monograph, showing
1876-411: The "primitive" forward-pointing hip seen in advanced troodontids and oviraptorosaurs is an evolutionary reversal, and that these groups evolved from ancestors with backward-pointing hips. Holtz and Osmólska (2004) diagnosed the clade Maniraptora based on the following characters: reduced or absent olecranon process of the ulna , greater trochanter and cranial trochanter of the femur fused into
1943-461: The Avialae, and these two points suggested that the ancestral dromaeosaurid could not glide or fly. Based on this cladistic analysis, Mahakala suggests that the ancestral condition for dromaeosaurids is non- volant . However, in 2012, an expanded and revised study incorporating the most recent dromaeosaurid finds recovered the Archaeopteryx -like Xiaotingia as the most primitive member of
2010-675: The Early Cretaceous (145–140 million years ago), and they survived until the end of the Cretaceous ( Maastrichtian stage, 66 ma), existing until the Cretaceous–Paleogene extinction event . The presence of dromaeosaurids as early as the Middle Jurassic has been suggested by the discovery of isolated fossil teeth, though no dromaeosaurid body fossils have been found from this period. Dromaeosaurids are diagnosed by
2077-461: The Maniraptora, rather than representing a single side-branch as previously thought. This led scientists such as Lindsay Zanno to conclude that the ancestral maniraptoran must have been omnivorous, giving rise to several purely herbivorous groups (such as the therizinosaurs, primitive oviraptorosaurs, and some avialans) and that, among non-avians, only one group reverted to pure carnivores (the dromaeosaurids). Most other groups fell somewhere in between
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2144-456: The ability to glide). Corfe and Butler criticized this work on methodological grounds. A challenge to all of these alternative scenarios came when Turner and colleagues in 2007 described a new dromaeosaurid, Mahakala , which they found to be the most basal and most primitive member of the Dromaeosauridae, more primitive than Microraptor . Mahakala had short arms and no ability to glide. Turner et al. also inferred that flight evolved only in
2211-418: The advanced maniraptoran group Aviremigia . More primitive maniraptorans, such as therizinosaurs (specifically Beipiaosaurus ), preserve a combination of simple downy filaments and unique elongated quills. Simple feathers are known from more primitive coelurosaurs such as Sinosauropteryx prima , and possibly from even more distantly related species such as the ornithischian Tianyulong confuciusi and
2278-409: The basal position of Microraptor , along with feather and wing features, as evidence that the ancestral dromaeosaurid could glide. In that case the larger dromaeosaurids would be secondarily terrestrial—having lost the ability to glide later in their evolutionary history. Also in 2002, Steven Czerkas described Cryptovolans , though it is a probable junior synonym of Microraptor . He reconstructed
2345-474: The clade Dromaeosauridae, which appears to suggest the earliest members of the clade may have been capable of flight. The authorship of the family Dromaeosauridae is credited to William Diller Matthew and Barnum Brown , who erected it as a subfamily (Dromaeosaurinae) of the family Deinodontidae in 1922, containing only the new genus Dromaeosaurus . The subfamilies of Dromaeosauridae frequently shift in content based on new analysis, but typically consist of
2412-420: The clade Unenlagiinae as all dromaeosaurids closer to Unenlagia than to Velociraptor ). The Microraptoria is the only dromaeosaurid sub-clade not converted from a subfamily. Senter and colleagues expressly coined the name without the subfamily suffix -inae to avoid perceived issues with erecting a traditional family-group taxon, should the group be found to lie outside dromaeosauridae proper. Sereno offered
2479-479: The clade would eventually give rise to the origin of flight in avian species. The following cladogram follows the results of a phylogenetic study by Cau (2020). † Alvarezsauroidea [REDACTED] † Therizinosauridae [REDACTED] † Oviraptorosauria [REDACTED] † Dromaeosauridae [REDACTED] † Troodontidae [REDACTED] Avialae [REDACTED] In 2002, Czerkas and Yuan reported that some maniraptoran traits, such as
2546-407: The discovery of Tsaagan lent support to this grouping, the inclusion of Deinonychus , Saurornitholestes, and a few other genera is still uncertain. The Dromaeosaurinae is usually found to consist of medium to giant-sized species, with generally box-shaped skulls (the other subfamilies generally have narrower snouts). The following classification of the various genera of dromaeosaurids follows
2613-436: The dromaeosaurid Deinonychus in a fast run, is among the most influential paleontological reconstructions in history. The dromaeosaurid body plan includes a relatively large skull, serrated teeth, narrow snout (an exception being the derived dromaeosaurines ), and forward-facing eyes which indicate some degree of binocular vision. Dromaeosaurids, like most other theropods, had a moderately long S-curved neck, and their trunk
2680-439: The earlier branch-based definition. The branch-based definition usually includes the major groups Dromaeosauridae , Troodontidae , Oviraptorosauria , Therizinosauria , and Avialae . Other taxa often found to be maniraptorans include the alvarezsaurs and Ornitholestes . Several taxa have been assigned to the Maniraptora more definitively, though their exact placement within the group remains uncertain. These forms include
2747-540: The family as a rank intermediate between order and genus was introduced by Pierre André Latreille in his Précis des caractères génériques des insectes, disposés dans un ordre naturel (1796). He used families (some of them were not named) in some but not in all his orders of "insects" (which then included all arthropods ). In nineteenth-century works such as the Prodromus of Augustin Pyramus de Candolle and
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2814-513: The flying pterosaurs . Thus it appears as if some form of feathers or down-like integument would have been present in all maniraptorans, at least when they were young. Maniraptora is the only dinosaur group known to include flying members, though how far back in this lineage flight extends is controversial. Powered and/or gliding flight is believed to have been present in some types of non-avialan paravians, including dromaeosaurids, such as Rahonavis and Microraptor . Zhenyuanlong suni ,
2881-423: The following features: short T-shaped frontals that form the rostral boundary of the supratemporal fenestra ; a caudolateral overhanging shelf of the squamosal ; a lateral process of the quadrate that contacts the quadratojugal ; raised, stalked, parapophyses on the dorsal vertebrae , a modified pedal digit II; chevrons and prezygapophysis of the caudal vertebrae elongate and spanning several vertebrae;
2948-415: The following groups. A number of dromaeosaurids have not been assigned to any particular subfamily, often because they are too poorly preserved to be placed confidently in phylogenetic analysis (see section Phylogeny below) or are indeterminate, being assigned to different groups depending on the methodology employed in different papers. The most basal known subfamily of dromaeosaurids is Halszkaraptorinae,
3015-469: The fossil inaccurately with only two wings and thus argued that dromaeosaurids were powered fliers, rather than passive gliders. He later issued a revised reconstruction in agreement with that of Microraptor Other researchers, like Larry Martin , have proposed that dromaeosaurids, along with all maniraptorans, were not dinosaurs at all. Martin asserted for decades that birds were unrelated to maniraptorans, but in 2004 he changed his position, agreeing that
3082-483: The fossil record during the Jurassic Period (see Eshanosaurus ), and survive today as living birds. Maniraptorans are characterized by long arms and three-fingered hands (though reduced or fused in some lineages), as well as a "half-moon shaped" (semi- lunate ) bone in the wrist ( carpus ). In 2004, Tom Holtz and Halszka Osmólska pointed out six other maniraptoran characters relating to specific details of
3149-527: The ground or 'retracted' when walking), which is thought to have been used in capturing prey and climbing trees (see "Claw function" below). This claw was especially blade-like in the large-bodied predatory eudromaeosaurs . One possible dromaeosaurid species, Balaur bondoc , also possessed a first toe which was highly modified in parallel with the second. Both the first and second toes on each foot of B. bondoc were also held retracted and bore enlarged, sickle-shaped claws. Dromaeosaurids had long tails. Most of
3216-401: The ground, fossilized footprint tracks confirm that many early paravian groups, including the dromaeosaurids, held the second toe off the ground in a hyperextended position, with only the third and fourth toes bearing the weight of the animal. This is called functional didactyly. The enlarged second toe bore an unusually large, curved, falciform (sickle-shaped, alt. drepanoid ) claw (held off
3283-495: The larger dromaeosaurids lost some or all of their insulatory covering, the discovery of feathers in Velociraptor specimens has been cited as evidence that all members of the family retained feathers. More recently, the discovery of Zhenyuanlong established the presence of a full feathered coat in relatively large dromaeosaurids. Additionally, the animal displays proportionally large, aerodynamic wing feathers, as well as
3350-430: The larger dromaeosaurids were secondarily flightless, like the modern ostrich . In 1988, Paul suggested that dromaeosaurids may actually be more closely related to modern birds than to Archaeopteryx . By 2002, however, Paul placed dromaeosaurids and Archaeopteryx as the closest relatives to one another. In 2002, Hwang et al. found that Microraptor was the most primitive dromaeosaurid. Xu and colleagues in 2003 cited
3417-439: The name Maniraptora, which means "hand snatchers" in relation to their 'seizing hands'). In 1994, Thomas R. Holtz attempted to define the group based on the characteristics of the hand and wrist alone (an apomorphy-based definition), and included the long, thin fingers, bowed, wing-like forearm bones, and half-moon shaped wrist bone as key characters. Most subsequent studies have not followed this definition, however, preferring
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#17327809250373484-413: The non-maniraptoran group Ornithomimosauria also descended from flying ancestors. The Maniraptora was originally named by Jacques Gauthier in 1986, for a branch-based clade defined as all dinosaurs closer to modern birds than to the ornithomimids . Gauthier noted that this group could be easily characterized by their long forelimbs and hands, which he interpreted as adaptations for grasping (hence
3551-400: The phylogenetic analysis conducted in 2017 by Cau et al. using the updated data from the Theropod Working Group in their description of Halszkaraptor . Halszkaraptor [REDACTED] Mahakala [REDACTED] Hulsanpes [REDACTED] Austroraptor [REDACTED] Buitreraptor Family (biology) Family ( Latin : familia , pl. : familiae )
3618-513: The presence of a subglenoid fossa on the coracoid . Dromaeosaurids were small to medium-sized dinosaurs, ranging from 1.5–2.07 metres (4.9–6.8 ft) in length (in the case of Velociraptor ) to approaching or over 6 m (20 ft) (in Utahraptor , Dakotaraptor and Achillobator ). Large size appears to have evolved at least twice among dromaeosaurids; once among the dromaeosaurines Utahraptor and Achillobator , and again among
3685-581: The presence of quill knobs, the attachment points for wing feathers possessed by some birds. The dromaeosaurids Rahonavis and Velociraptor have both been found with quill knobs, showing that these forms had feathers despite no impressions having been found. In light of this, it is most likely that even the larger ground-dwelling dromaeosaurids bore feathers, since even flightless birds today retain most of their plumage, and relatively large dromaeosaurids, like Velociraptor , are known to have retained pennaceous feathers. Though some scientists had suggested that
3752-575: The seventy-six groups of plants he recognised in his tables families ( familiae ). The concept of rank at that time was not yet settled, and in the preface to the Prodromus Magnol spoke of uniting his families into larger genera , which is far from how the term is used today. In his work Philosophia Botanica published in 1751, Carl Linnaeus employed the term familia to categorize significant plant groups such as trees , herbs , ferns , palms , and so on. Notably, he restricted
3819-444: The skeleton. Unlike most other saurischian dinosaurs, which have pubic bones that point forward, several groups of maniraptorans have an ornithischian -like backwards-pointing hip bone. A backward-pointing hip characterizes the therizinosaurs , dromaeosaurids , avialans , and some primitive troodontids . The fact that the backward-pointing hip is present in so many diverse maniraptoran groups has led most scientists to conclude that
3886-517: The table provided in Holtz, 2011 unless otherwise noted. Dromaeosauridae was first defined as a clade by Paul Sereno in 1998, as the most inclusive natural group containing Dromaeosaurus but not Troodon , Ornithomimus or Passer . The various "subfamilies" have also been re-defined as clades, usually defined as all species closer to the groups namesake than to Dromaeosaurus or any namesakes of other sub-clades (for example, Makovicky defined
3953-428: The tail vertebrae bore bony, rod-like extensions (called prezygapophyses), as well as bony tendons in some species. In his study of Deinonychus , Ostrom proposed that these features stiffened the tail so that it could only flex at the base, and the whole tail would then move as a single, rigid, lever. However, one well-preserved specimen of Velociraptor mongoliensis (IGM 100/986) has an articulated tail skeleton that
4020-644: The two extremes, with alvarezsaurids and some avialans being insectivorous, and with advanced oviraptorosaurs and troodontids being omnivorous. A 2023 study analyzing fossil eggshells assigned to Troodon with clumped isotope thermometry found that Troodon , and likely other non-avian maniraptorans, had a slowed calcification of eggs akin to that of most reptiles. This contrasts with the rapid calcification of eggs found in modern birds, indicating that most maniraptorans aside from birds retained this basal trait. This would also indicate that most non-avian maniraptorans possessed two functional ovaries , contrasting with
4087-445: The two were close relatives. However, Martin believed that maniraptorans were secondarily flightless birds, and that birds did not evolve from dinosaurs, but rather from non-dinosaurian archosaurs. In 2005, Mayr and Peters described the anatomy of a very well preserved specimen of Archaeopteryx , and determined that its anatomy was more like non-avian theropods than previously understood. Specifically, they found that Archaeopteryx had
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#17327809250374154-448: The unenlagiines, some species may have been capable of active flight. The most advanced subgroup of dromaeosaurids, Eudromaeosauria, includes stocky and short-legged genera which were likely ambush hunters. This group includes Velociraptorinae, Dromaeosaurinae, and in some studies a third group: Saurornitholestinae. The subfamily Velociraptorinae has traditionally included Velociraptor , Deinonychus , and Saurornitholestes , and while
4221-549: The use of this term solely within the book's morphological section, where he delved into discussions regarding the vegetative and generative aspects of plants. Subsequently, in French botanical publications, from Michel Adanson 's Familles naturelles des plantes (1763) and until the end of the 19th century, the word famille was used as a French equivalent of the Latin ordo (or ordo naturalis ). In zoology ,
4288-403: The word "bird", or "Aves", that are based on the possession of feathers. However, other scientists, such as Lawrence Witmer , have argued that calling a theropod like Caudipteryx a bird because it has feathers may stretch the word past any useful meaning. At least two schools of researchers have proposed that dromaeosaurids may actually be descended from flying ancestors. Hypotheses involving
4355-653: The work of Norell et al. , including new characters and better fossil evidence, to determine that birds (avialans) were better thought of as cousins to the dromaeosaurids and troodontids . The consensus of paleontologists is that there is not yet enough evidence to determine whether any dromaeosaurids could fly or glide, or whether they evolved from ancestors that could. Dromaeosaurids are so bird-like that they have led some researchers to argue that they would be better classified as birds. First, since they had feathers, dromaeosaurids (along with many other coelurosaurian theropod dinosaurs) are "birds" under traditional definitions of
4422-423: Was Sinornithosaurus , reported from China by Xu et al. in 1999. Many other dromaeosaurid fossils have been found with feathers covering their bodies, some with fully developed feathered wings. Microraptor even shows evidence of a second pair of wings on the hind legs. While direct feather impressions are only possible in fine-grained sediments, some fossils found in coarser rocks show evidence of feathers by
4489-428: Was relatively short and deep. Like other maniraptorans , they had long arms that could be folded against the body in some species, and relatively large hands with three long fingers (the middle finger being the longest and the first finger being the shortest) ending in large claws. The dromaeosaurid hip structure featured a characteristically large pubic boot projecting beneath the base of the tail. Dromaeosaurid feet bore
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