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Velociraptor

2007 Schools Wikipedia Selection. Related subjects: Dinosaurs

       iVelociraptor

                        Fossil range: Late Cretaceous

   Velociraptor skeletal anatomy, showing enlarged hind claw.
   Velociraptor skeletal anatomy, showing enlarged hind claw.

                             Conservation status

   Extinct (fossil)
                   Scientific classification

   Kingdom:    Animalia
   Phylum:     Chordata
   Class:      Sauropsida
   Superorder: Dinosauria
   Order:      Saurischia
   Suborder:   Theropoda
   Infraorder: Coelurosauria
   Family:     Dromaeosauridae
   Subfamily:  Velociraptorinae
               Barsbold, 1983
   Genus:      Velociraptor
   Species:    V. mongoliensis

                                Binomial name

   Velociraptor mongoliensis
   Osborn, 1924

                                  Synonyms

     "Ovoraptor djadochtari"
   Osborn, 1924 ( nomen nudum)

   Velociraptor (meaning "swift thief") is a genus of dromaeosaurid
   theropod dinosaur that existed approximately 83 to 70 million years ago
   during the later part of the Cretaceous Period. There is only one
   universally recognized species, V. mongoliensis, although others have
   been attributed in the past. Fossils of this species have been found in
   central Asia, from both Inner and Outer Mongolia.

   Smaller than other dromaeosaurids like Deinonychus and Achillobator,
   the turkey-sized Velociraptor nevertheless shared many of the same
   anatomical features. It was a bipedal carnivore with a long, stiffened
   tail and had an enlarged, sickle-shaped claw on each hindfoot, which is
   thought to have been used to kill its prey. Velociraptor can be
   distinguished from other dromaeosaurids by its long and low skull, with
   an upturned snout.

   Due in large part to its prominent role in Michael Crichton's novel
   Jurassic Park and the subsequent motion picture series, Velociraptor
   (commonly shortened to 'raptor') is one of the dinosaur genera most
   familiar to the general public. It is also well-known to
   paleontologists, with over a dozen recovered fossil skeletons — the
   most of any dromaeosaurid. One particularly famous specimen shows a
   Velociraptor locked in combat with a Protoceratops.

Description

   Velociraptor compared in size to a human
   Enlarge
   Velociraptor compared in size to a human

   Velociraptor was small for a dromaeosaurid, with adults measuring up to
   1.798 meters (5.9 ft) long, 0.62 meters (2 ft) high at the hip, and
   weighing 20 kilograms (45  lb). The skull, which grew up to
   249 millimeters (9.80 in) long, was uniquely up-curved, with a concave
   upper surface and convex lower. The jaws were lined with 26–28
   widely-spaced teeth on each side, each more strongly serrated on the
   back edge than the front — possibly an adaptation that improved its
   ability to catch and hold fast-moving prey.

   Velociraptor, like other dromaeosaurids, had three strongly-curved
   claws on each forelimb and large 'hands', which were similar in
   construction and flexibility to the wing bones of modern birds. Of the
   three digits present, the first was shortest and the second longest.
   The structure of the carpal bones prevented pronation of the wrist and
   forced the 'hands' to be held with the palmar surface facing inwards
   (medially), not downwards. Unlike most theropod dinosaurs, which had
   three functional toes on the hindlimb, dromaeosaurids like Velociraptor
   walked on only their third and fourth digits. The first digit, as in
   other theropods, was a small dewclaw. The second digit, for which
   Velociraptor is most famous, was highly modified and held retracted off
   of the ground. It bore a relatively large, sickle-shaped claw, typical
   of dromaeosaurid and troodontid dinosaurs. This enlarged claw, up to
   67 millimeters (2.6 in) long around its outer edge, was most likely a
   predatory device, used to tear into the prey, possibly delivering a
   fatal blow.

   The tail of Velociraptor was stiffened, both by long bony projections
   (prezygapophyses) from the upper surfaces of the vertebrae and by
   ossified tendons underneath. The prezygapophyses began on the tenth
   tail (caudal) vertebra and extended forward to brace four to ten
   additional vertebrae, depending on position in the tail. The stiffening
   forced the entire tail to act as a single rod-like unit, preventing
   vertical motion between vertebrae. However, at least one specimen
   preserves a series of intact tail vertebrae in an S-shaped curve,
   suggesting that there was considerably more horizontal flexibility.
   These adaptations of the tail probably provided balance and stability
   while turning, especially at high speeds.

History

   An American Museum of Natural History expedition to the Mongolian Gobi
   desert in 1922 recovered the first Velociraptor fossil known to
   science: a crushed but complete skull, associated with one of the
   raptorial second toe claws. Two years later, museum president Henry
   Fairfield Osborn mentioned the animal in a popular press article, under
   the name "Ovoraptor djadochtari" (not to be confused with the similarly
   named Oviraptor). However, because the name "Ovoraptor" was not
   published in a scientific journal or accompanied by a formal
   description, it remained a nomen nudum ("naked name"), and the name
   Velociraptor retains priority. Later that year, Osborn designated the
   skull and claw (which he assumed came from the hand) as the type
   specimen of his new genus, Velociraptor. This name is derived from the
   Latin words velox (meaning 'swift') and raptor (meaning 'robber' or
   'plunderer') and refers to the animal's cursorial nature and
   carnivorous diet. Osborn named the type species V. mongoliensis after
   its country of origin.

   While North American teams were shut out of Mongolia, during the Cold
   War, expeditions by Soviet and Polish scientists, in collaboration with
   Mongolian colleagues, recovered several more specimens of Velociraptor.
   The most famous is part of the legendary "Fighting Dinosaurs" specimen,
   discovered by a Polish-Mongolian team in 1971. This fossil preserves a
   single Velociraptor in the midst of battle against a lone
   Protoceratops.

   Between 1988 and 1990, a joint Chinese-Canadian team discovered
   Velociraptor remains in northern China; joint Mongolian-American
   expeditions to the Gobi, led by the American Museum of Natural History
   and the Mongolian Academy of Sciences, turned up several well-preserved
   skeletons between 1990 and 1995.

Provenance

   All known specimens of Velociraptor mongoliensis were discovered in the
   Djadochta Formation of the Mongolian province of Ömnögovi, or of
   Chinese Inner Mongolia. A species of Velociraptor, possibly V.
   mongoliensis, is also preserved in the slightly younger Barun Goyot
   Formation of Mongolia. These geologic formations are estimated to date
   back to the Campanian stage (about 83 to 70 million years ago) of the
   Late Cretaceous Epoch.

   V. mongoliensis has been found at many of the most famous Djadochta
   localities. The type specimen was discovered at the Flaming Cliffs site
   (also known as Bayn Dzak and Shabarakh Usu), while the "Fighting
   Dinosaurs" were found at the Tugrig locality (also known as Tugrugeen
   Shireh). More recently, fossils of V. mongoliensis were recovered from
   Bayan Mandahu, a prolific site from the Djadochta of Inner Mongolia in
   China. A dromaeosaurid skull, currently known only as IGM 100/1015, was
   recovered from the site called Ukhaa Tolgod and may represent a new
   species of Velociraptor, but is not V. mongoliensis. The well-known
   Barun Goyot localities of Khulsan and Khermeen Tsav have also produced
   remains which may also belong to the genus Velociraptor.

   All of these sites preserve an arid environment with fields of sand
   dunes and only intermittent streams, although the younger Barun Goyot
   environment seems to have been slightly wetter than the older
   Djadochta. Aside from Protoceratops, upon which it preyed, Velociraptor
   shared its environment with other basal ceratopsians, like
   Udanoceratops and ankylosaurids, like Pinacosaurus, along with several
   species of oviraptorid, troodontid, and alvarezsaurid theropods.

Taxonomy

   Velociraptor is a member of the subfamily Velociraptorinae, a derived
   sub-group of the larger family Dromaeosauridae. In phylogenetic
   taxonomy, Velociraptorinae is usually defined as "all dromaeosaurs more
   closely related to Velociraptor than to Dromaeosaurus." Dromaeosaurid
   classification is highly variable. Originally, the subfamily
   Velociraptorinae was erected solely to contain Velociraptor. Other
   analyses have included other genera, usually Deinonychus and
   Saurornitholestes. A recent cladistic analysis indicated that this
   subfamily may only contain Deinonychus and the specimen IGM 100/1015,
   which may be a species of Velociraptor.
   Life restoration of Velociraptor
   Enlarge
   Life restoration of Velociraptor

   In the past, other dromaeosaurid genera, including Deinonychus and
   Saurornitholestes, have sometimes been classified with Velociraptor
   within a single genus. Since Velociraptor was the first to be named,
   the species Deinonychus antirrhopus and Saurornitholestes langstoni
   were sunk into Velociraptor, as V. antirrhopus and V. langstoni.
   However, the only currently recognized species of Velociraptor is V.
   mongoliensis.

   When first described in 1924, Velociraptor was placed in the family
   Megalosauridae, as was the case with most carnivorous dinosaurs at the
   time (Megalosauridae, like Megalosaurus, functioned as a sort of
   'wastebin' taxon, where many unrelated species were grouped together).
   As dinosaur discoveries multiplied, Velociraptor was later recognized
   as a dromaeosaurid. All dromaeosaurids have also been referred to the
   family Archaeopterygidae by at least one author (which would, in
   effect, make Velociraptor a flightless bird).

   Whether Velociraptor was a bird or a dinosaur depends on the definition
   being used. Phylogenetically, all members of the clade Aves are
   dinosaurs. However, in Linnean taxonomy and common terminology, a
   "bird" is not just a member of Aves but any animal with feathers. Under
   the latter definition, Velociraptor and all maniraptoran dinosaurs are
   actually birds, since feather-bearing animals are known from every
   maniraptoran group. Recently, fossils of dromaeosaurids more primitive
   than Velociraptor have been found in China, with feathers covering
   their bodies and fully-developed, feathered wings. In light of this, it
   is most likely that Velociraptor bore feathers too, since even
   flightless birds today retain most of their feathers. While there is,
   as yet, no fossil evidence to confirm that Velociraptor had feathers,
   there is no reason to suspect it of being an exception.

   It has been recently suggested that Velociraptor and other
   dromaeosaurids were true birds, both under the phylogenetic definition
   and under the common usage of the word. Basal dromaeosaurids, such as
   Microraptor and Rahonavis, have been found to have had even more
   bird-like characters than derived forms like Velociraptor, some even
   having flight capability - possibly indicating that Velociraptor was
   secondarily flightless, like an ostrich. The discovery, in 2005, of the
   Thermopolis specimen of Archaeopteryx, which preserves a
   dromaeosaurid-like hyperextendible second toe, may mean that
   Archaeopteryx itself is more basal than Velociraptor. If this is true,
   then all dromaeosaurids must be considered true birds and members of
   Aves by definition, as Aves is defined to include Archaeopteryx, all
   living birds and all descendents of their most common ancestor.

Paleobiology

Predatory behaviour

   The "Fighting Dinosaurs" specimen of Velociraptor and Protoceratops, on
   display at the American Museum of Natural History
   Enlarge
   The "Fighting Dinosaurs" specimen of Velociraptor and Protoceratops, on
   display at the American Museum of Natural History

   The "Fighting Dinosaurs" specimen, found in 1971, preserves a
   Velociraptor and Protoceratops in combat and provides direct evidence
   of predatory behaviour. When originally reported, it was hypothesized
   that the two animals drowned. However, taking into account the fact
   that the animals were preserved in ancient sand dune deposits, it is
   now thought that the animals were buried in sand, either from a
   collapsing dune or while trapped in a sandstorm. Burial must have been
   extremely fast, judging from the lifelike poses in which the animals
   were preserved. Both forelimbs and one hindlimb of the Protoceratops
   are missing, which has been seen as evidence of scavenging by other
   animals.

   The distinctive claw, on the second digit of dromaeosaurids, has
   traditionally been depicted as a slashing weapon; its assumed use being
   to cut and disembowel prey. In the "Fighting Dinosaurs" specimen, the
   Velociraptor lies underneath, with one of its sickle claws apparently
   embedded in the throat of its prey, while the beak of Protoceratops is
   clamped down upon the right forelimb of its attacker. This suggests
   Velociraptor may have used its sickle claw for precision killing by
   piercing vital organs such as the jugular vein, carotid artery, or
   trachea (windpipe) rather than slashing the abdomen. The inside edge of
   the claw was rounded and not at all sharp, which may have precluded any
   sort of cutting or slashing action, although only the bony core of the
   claw is known, so the keratin sheath may have had a sharper edge.
   However, it is unlikely that any sharp edge could be maintained, as the
   claw was not retractable for its protection, nor could it easily be
   sharpened by scraping against other objects, as seen in cats. The thick
   abdominal wall of skin and muscle would have been difficult to slash
   with such a dull cutting surface. The slashing hypothesis was tested
   during a 2005 BBC documentary, The Truth About Killer Dinosaurs. The
   producers of the program created an artificial Velociraptor leg with a
   sickle claw and used a pork belly to simulate the dinosaur's prey. The
   sickle claw did not fully penetrate the abdominal wall, indicating that
   the claw was not used to disembowel prey.

   Remains of Deinonychus, a closely related dromaeosaurid, have commonly
   been found in aggregations of several individuals. Deinonychus is also
   occasionally found in association with a larger herbivore,
   Tenontosaurus, which has been seen as evidence of cooperative hunting.
   However, although many fossils of Velociraptor and other dromaeosaurids
   have been found in Mongolia, all have been isolated specimens not
   closely associated with any others. Therefore, while Velociraptor is
   commonly depicted as a pack hunter, as in the movie Jurassic Park, no
   fossil evidence currently supports this theory.

Metabolism

   Velociraptor was probably warm-blooded to some degree, as it required a
   significant amount of energy to hunt. Modern animals that possess
   feathery or furry coats, like Velociraptor likely did, tend to be
   warm-blooded, since these coverings function as insulation. However,
   bone growth rates in dromaeosaurids and some early birds suggest a more
   moderate metabolism, compared with most modern warm-blooded mammals and
   birds. The kiwi is similar to dromaeosaurids in anatomy, feather type,
   bone structure and even the narrow anatomy of the nasal passages
   (usually a key indicator of metabolism). The kiwi is a highly active,
   if specialized, flightless bird, with a stable body temperature and a
   fairly low resting metabolic rate, making it a good model for the
   metabolism of primitive birds and dromaeosaurids.

In popular culture

   Velociraptor is well-known in its role as a vicious and cunning killer,
   from the 1990 novel Jurassic Park by Michael Crichton, and its 1993
   film adaptation, directed by Steven Spielberg. The "raptors" portrayed
   in Jurassic Park were modelled after a slightly larger relative,
   Deinonychus, which some scientists at the time called Velociraptor
   antirrhopus. The paleontologists in the film and the novel excavate a
   Velociraptor skeleton in Montana, where Deinonychus fossils would be
   found, far from the central Asian range of Velociraptor. A character in
   Crichton's novel also states that "...Deinonychus is now considered one
   of the velociraptors", indicating that Crichton used this taxonomy,
   though the "raptors" in the novel are referred to as V. mongoliensis.

   The Velociraptor depicted in the Jurassic Park films were
   scientifically inaccurate in numerous ways. One major discrepancy,
   possibly explained by the fact that Deinonychus was used as a model, is
   that the size of the Velociraptor in the film was much greater than
   their diminutive real-world counterparts. The size of the film's
   Velociraptor may also have been increased for dramatic reasons by
   director Steven Spielberg. The film versions of Velociraptor were also
   covered in scales. No evidence of body scales has been reported for any
   maniraptoran dinosaur and it is more likely that they were covered in
   feathers, though no direct fossil evidence of integument of any kind
   exists for Velociraptor itself. Jurassic Park III does depict a type of
   feathers on its Velociraptor, quill-like structures along the back of
   the head and neck, although these do not resemble the down-like
   feathers known from real-life dromaeosaurids. Additionally, the
   forelimbs of the film animals did not closely resemble those of real
   dromaeosaurids and their tails were too short and flexible, anatomical
   errors which directly contradict fossil evidence. In the sequel film
   Jurassic Park III, one character states that Velociraptor were smarter
   than dolphins, whales and primates. Based on fossil evidence, this is
   highly unlikely, and it is more probable that, while intelligent by
   dinosaur standards, they were less intelligent than modern big cats.
   The robotic toy Roboraptor
   Enlarge
   The robotic toy Roboraptor

   Since the success of Jurassic Park, Velociraptor has become a
   ubiquitous representation of dinosaurs in popular culture. It has
   appeared in several other films and television programs, including
   several of The Land Before Time animated films and a spin-off of the
   Transformers television series, Beast Wars. Velociraptor was also
   featured in three documentary programs, The Discovery Channel's
   Dinosaur Planet, most notably a female trying to locate a pack, a
   special of the BBC's Walking With... series (" The Giant Claw"),
   attacking a Protoceratops and The Truth About Killer Dinosaurs, another
   BBC production which featured Velociraptor in an animated fight with an
   Ankylosaurus.

   Velociraptor has also appeared in the realms of music and sport. For
   example, the Toronto Raptors, an NBA franchise, adopted a stylised
   Velociraptor as their logo, while the band Norma Jean named their 2005
   tour the "Velociraptour". There is also a robotic toy based on
   Velociraptor, called Roboraptor. Aside from titles based on Jurassic
   Park, Velociraptor has also been featured in other video games,
   including the Dino Crisis series, Carnivores, and World of Warcraft.
     * Dinobot's beast form in the Beast Wars television series was that
       of a Velociraptor.

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