Velociraptor
Velociraptor (lat. "speedy thief") is a genus with two known species of dromaeosaurid theropod dinosaurs that lived towards the end of the Cretaceous period, 75 to 71 million years ago, during the Campania, in present-day Asia. Only one species, Velociraptor mongoliensis, has long been recognized, whose fossils have been found in Central Asia, in Mongolia, but a second species, Velociraptor osmolskae, was named in 2008 from cranial material from Inner Mongolia, China.
Although smaller than other dromaeosaurids such as Deinonychus and Achillobator, Velociraptor had many similar anatomical features to them. It was a bipedal carnivore, with a long, stiff tail, and large sickle-shaped claws on each leg, which probably made it easier for it to kill its prey. Unlike other dromaeosaurids, velociraptor had a low, elongated skull and a flat, upturned snout. It had long hind legs, which expresses (like the name) its apparent great speed.
Due to his prominent appearance in Michael Crichton's novel Jurassic Park, Velociraptor, in the film his name is often abbreviated to "raptor" or "raptors". and they are represented much larger, it is one of the genera of dinosaurs best known by the general public. In real life, Velociraptor was about the size of a turkey, considerably smaller than the roughly seven-foot-tall, two-hundred-pound reptiles featured in novels and movies, which were based on Deinonychus, which had been proposed as a species of the genus, was rejected by scientists. It is also well known to paleontologists, with no less than a dozen fossil skeletons unearthed, the most ever discovered for a dromaeosaurid. A particularly famous specimen is the one showing a Velociraptor engaged in battle with a Protoceratops.
Description
For a dromaeosaurid, Velociraptor was relatively small, smaller than Deinonychus and Achillobator; adults averaged about 1 inch in length. 8 meters, and 0.5 meters tall at the hip, weighing about fifteen kilograms. The size ranges from 1.5 to 2.07 meters long, with a body mass between 15 and 18, 3 kilograms.
It is possible that Velociraptor was covered in feathers, not only covering down but also complex feathers on its forearms similar to the remiges of modern birds. However, this curious animal could never fly. Prominent attachment points on forearms, possible attachment sites for "wing" and direct indicators of a feather covert, have been reported from the ulna of a single Velociraptor specimen, IGM 100/981, which represents an animal of about 1.5 meters long and fifteen kilograms in weight. The spacing of six preserved bumps suggests that eight additional bumps may have been present, giving a total of fourteen bumps on which developed large secondary feathers, "wing" which are derived from the forearm. However, the sample number has been corrected to IGM 100/3503 and its referral to Velociraptor may require reassessment, pending further studies. However, there is strong phylogenetic evidence for other dromaeosaurid relatives indicating the presence of feathers in Velociraptor, including dromaeosaurids such as Microraptor or Zhenyuanlong i>.
Skull
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The skull, about nine inches long, had a unique upward-curving shape, with a concave upper surface and a convex lower surface. The snout, which took up about 60% of the total length of the skull, was remarkably narrow, consisting mainly of the nasal, premaxillary, and maxillary bones. The premaxilla was the most anterior bone of the skull and was longer than it was tall. While its posterior end joined the nasal, the main body of the premaxilla touched the maxilla. The maxilla was almost triangular in shape and was the largest element of the snout. In its center or main body, there was a depression that developed a small oval-shaped or circular hole, called the maxillary fenestra. In front of this fenestra were two small openings, called promaxillary fenestrae. The posterior edge of the maxilla predominantly formed the antorbital fenestra, one of several large openings in the skull. Both the premaxilla and the maxilla had several tooth sockets on their lower surfaces. Above the maxilla and making contact with the premaxilla, was the nasal bone. It was a thin, narrow, elongated bone that contributed to the upper surface of the snout. Together, both the premaxilla and the nasal bones formed the nare or narial fenestra, the opening of the nostril, which was relatively large and circular. The posterior end of the nasal was joined by the frontal and lacrimal bones.
The posterior or anterior region of the skull was formed by the frontal, lacrimal, postorbital, jugal, parietal, quadrate, and quadratojugal bones. The front was a large element, vaguely rectangular in shape when viewed from above. At its posterior end, this bone was in contact with the parietal bone and these elements were the main bodies of the skull roof. The lacrimal was a T shaped bone and its main body was thin and delicate. Its lower end meets the jugal, often called the cheekbone, which was a large element of a subtriangular shape. Its lower edge was remarkably straight and horizontal. The postorbital was located just above the jugal, a stubby bone with a strong T shape. As a whole, the orbit or orbital fenestra, the cavity of the eye, formed by the lacrimal, the jugal, the frontal and the postorbital, was large and almost circular in shape, being longer than it was high. When viewed from above, a pair of large, sharply rounded foramina were present near the back of the skull, the temporal windows, the main components of which were the postorbital and squamosal. Behind the jugal, an inverted T shaped bone, also seen in other dromaeosaurids, developed, known as the quadratus jugal. While the upper end of the quadratojugal was joined to the squamosal, an element of irregular shape, its inner side meets the quadrate. The latter was of great importance for the articulation with the lower jaw. The most posterior bone was the occipital bone and its projection the occipital condyle, a rounded, bulbous protrusion that meets the first vertebra of the neck.
The lower jaw of Velociraptor mainly comprised the dentary, splenial, angular, surangular, and articular bones. The dentary was a very long, slightly curved and narrow element that developed several alveoli on its upper surface. At its posterior end it joins the surangular. It had a small hole near its posterior end, called the surangular foramen or fenestra. Both bones were the largest elements of the Velociraptor lower jaw, contributing practically its entire length. Below them were the smaller splenia and angulars, closely articulated with each other. The articular, located on the inner face of the surangular, was a small element that joined the square of the upper skull, allowing articulation with the lower jaw. An elongated, almost oval hole developed in the center of the lower jaw, the mandibular fenestra, and was produced by the articulation of the dentary, surangular, and angular bones.
The teeth of Velociraptor were fairly homodont, equal in shape, and had several denticles, each more serrated on the trailing edge than on the front. The premaxilla had four sockets, meaning four teeth developed, and the maxilla had eleven sockets. In the dentary, between fourteen and fifteen alveoli were present. All the teeth present in the premaxilla were badly curved, with the first two teeth being the longest, and the second having a characteristically large size. The maxillary teeth were thinner, recurved, and, above all, the lower end was considerably more serrated than the upper, possibly an adaptation that enhanced its ability to catch and hold swift prey.
Upper limbs
The arm of Velociraptor was made up of the humerus, the upper arm bone, the radius and ulna, the forearm and hand bones. Velociraptor, like other dromaeosaurids, had a large hand with three elongated fingers ending in strongly curved unguals, claw bones, which were similar in construction and flexibility to the wing bones of birds. modern. The second digit was the longest of the three digits present, while the first was the shortest. The first of these three phalanges was the shortest, the second being the longest. The structure of the carpal bones, the wrist, prevented pronation of the wrist and forced the palm surface to be held inward, medially, not downward.
Lower limbs
Just like birds, their pubis pointed backwards, not forwards like most theropods. Unlike most theropods, which had three functional toes on each hind limb, dromaeosaurids such as Velociraptor walked on only their third and fourth toes. The anatomy of the Velociraptor foot consisted of the metatarsal, a large element composed of three metatarsals, of which the first was extremely small in size, and four toes that developed large nails. The first toe, as in other theropods, was a small vestigial claw, separate from the others and without any function. The second finger, to which Velociraptor owes part of its fame, was highly modified and remained retracted without touching the ground. It carried a huge sickle-shaped claw, typical of dromaeosaurid and troodontid dinosaurs. This elongated claw, about 65 millimeters long at its outer edge, was probably a hunting tool capable of inflicting fatal wounds. The kicking muscles of the leg and toe flexors were well developed. and they made the claw work like a deadly switchblade. Conventionally, it has been believed that this animal rested on one of its hind legs and launched an attack with the other, the tail functioning as a seesaw.
Axial skeleton
The tail of Velociraptor was rigid, with long bony projections, zygoapophyses, at the top of each vertebra and with ossified tendons under it. The prezygoapophyses began at the tenth caudal vertebra and extended forward to reinforce an additional four to ten vertebrae, depending on the position of the tail. The stiffness strengthened the entire tail allowing it to act as a bar-like unit, preventing vertical movement between the vertebrae. However, at least one specimen preserves a series of caudal vertebrae intact in an 'S'-shaped curve, suggesting that there was considerable horizontal flexibility. These tail adaptations probably provide balance and stability when turning, especially at high speeds. It is a mechanism similar to, and in evolutionary convergence with, the tail of cheetahs.
Discovery and research
During an American Museum of Natural History expedition to the Flaming Cliffs, called Bayn Dzak or Bayanzag in the local language, of the Djadochta Formation, Gobi Desert of Mongolia, on August 11, 1923, Peter Kaisen discovered the first fossil of Known Velociraptor. This is a broken and crushed but complete skull, associated with one of the raptorial second toe claws of the paw. They were cataloged as AMNH 6515. In early 1924, museum president Henry Fairfield Osborn mentioned the animal in an article, under the name Ovoraptor djadochtari (not to be confused with another genus with a similar name, Oviraptor). But because the name Ovoraptor had not been published in a scientific journal or accompanied by a formal description, it remained invalid. 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, the genitive of which, velocis, refers to the carnivorous diet and running nature of the animal. This last feature was contradictory to the idea of slow and unintelligent dinosaurs that used to be put forward at that time. At the same time he named the type species V. mongoliensis in honor of its country of origin. Due to the above, the latter is considered a valid name for the genus and the species.
While American scientists were kept away from communist Mongolia during the Cold War, expeditions of Soviet and Polish scientists, in collaboration with Mongolian colleagues, unearthed many Velociraptor specimens. The most famous is part of the "The Fighting Dinosaurs" specimen, MPC-D 100/25, formerly IGM, GIN or GI SPS, discovered by a Polish-Mongolian team in 1971. The fossil preserves a Velociraptor in battle against a Protoceratops. It is considered a national treasure of Mongolia, and in 2000 it was loaned to the American Museum of Natural History in the city New York for a temporary exhibition.
Between 1988 and 1990, a Chinese-Canadian team discovered Velociraptor remains in northern China. Also Mongolian-American expedition members, belonging to the American Museum of Natural History and the Mongolian Academy of Sciences, unearthed several well-preserved skeletons between 1990 and 1995. One of these specimens, IGM 100/980, it was nicknamed Ichabodcraniosaurus by Norell's team because it was a very complete specimen that was found without its skull, an allusion to Washington Irving's character Ichabod Crane. This specimen may belong to Velociraptor mongoliensis, but Norell and Makovicky concluded that it was not complete enough to say for sure, and awaits a formal description. Though Norell and Makovicky tentatively considered it a specimen of Velociraptor mongoliensis, was named as a new species, Shri devi in 2021.
A maxilla and a lacrimal, the bone that has most of the teeth of the upper jaw and the bone that forms the anterior edge of the eye socket, respectively, recovered in 1999 by the Sino-Belgian expeditions were considered as belonging to to Velociraptor, but not to the type species V. mongoliensis. Pascal Godefroit et al. named these bones V. osmolskae, by the Polish paleontologist Halszka Osmólska, in 2008, being the second species to be considered valid.
Paleontologists Mark A. Norell and Peter J. Makovicky, in 1997, described new and abundantly preserved specimens of V. mongoliensis, including MPC-D 100/985, collected from the Tugrik Shireh locality in 1993, and MPC-D 100/986, collected in 1993 in the town of Chimney Buttes. The team briefly mentioned another specimen, MPC-D 100/982, which at the time of this publication remained undescribed. In 1999, Norell and Makovicky provided more information on the anatomy of Velociraptor with additional specimens. Among these, MPC-D 100/982 was partially described and calculated, and referred to V. mongoliensis based mainly on cranial similarities with the holotype, although they stated that there were differences between the pelvic region of this specimen and other Velociraptor specimens. This relatively well-preserved specimen, including the skull, was discovered and collected in 1995 at the Bayn Dzak locality, more specifically at the "Volcano" sub-locality. Martin Kundrát, in a 2004 abstract, compared the neurocranium of MPC-D 100/982 with another specimen of Velociraptor, MPC-D 100/976. He concluded that the general morphology of the former was more derived or advanced than that of the latter, suggesting that they might represent different taxa.
Mark J. Powers, in his 2020 master's thesis, fully described MPC-D 100/982, which he concluded represents a new and third species of Velociraptor >. This species, which he named Velociraptor vadarostrum, was stated to differ primarily from other Velociraptor species in having a shallow maxillary morphology. Powers and colleagues also in 2020, used morphometric analyzes to compare several dromaeosaurid maxillae and found that the maxilla of MPC-D 100/982 differs greatly from specimens referred to Velociraptor. They indicated that this specimen, based on these results, represents a different species. In 2021 Powers and his team used principal component analysis to separate the maxillae of dromaeosaurids in particular, finding that MPC-D 100/982 falls outside the intraspecific variability of V. mongoliensis, arguing for a different species. They considered that both V. mongoliensis and this new species were ecologically separated based on their skull anatomy. In another 2021 abstract, the team again reinforced the separation at the species level, noting that additional differences can be found in the legs. rear.
Classification
Velociraptor is a member of the Eudromaeosauria group, a subgroup derived from the larger family Dromaeosauridae. Velociraptor is a member of the Velociraptorinae subfamily, a subgroup derived from the Dromaeosauridae family. In phylogenetic taxonomy, the group Velociraptorinae is usually defined as "all dromaeosaurids more closely related to Velociraptor than to Dromaeosaurus&# 3. 4;. The classification of dromaeosaurids is highly variable. Originally, the subfamily Velociraptorinae was created solely to contain Velociraptor. But other analyzes have included other genera in the category, usually Deinonychus and Saurornitholestes. A cladistic analysis indicated that this subfamily could only have contained Deinonychus and the specimen IGM 100/1015, which belongs to the genus Tsaagan. The work describing Tsaagan also includes a cladistic analysis that identifies the group Velociraptorinae as monophyletic, containing Velociraptor, Deinonychus, Tsaagan, and the closely related but doubtfully located Saurornitholestes. Several studies published during the 2010s, including expanded versions of analyzes found support for the Velociraptorinae, they failed to resolve it as a distinct group, instead suggesting that it is a paraphyletic grade that gave rise to the Dromaeosaurinae.
In the past, other genera of dromaeosaurids, including Deinonychus and Saurornitholestes, have sometimes been classified in the same genus with Velociraptor. Since Velociraptor was the first to be named, the species Deinonychus antirrhopus and Saurornitholestes langstoni would then be named V. antirrhopus and V. langstoni. However, only two species of Velociraptor are currently recognized, and these are V. mongoliensis and V. osmolskae.
In 1924, when it was described for the first time, Velociraptor was included in the family Megalosauridae, like most carnivores at that time. Megalosauridae, like Megalosaurus, functioned as a class of "recyclable" taxon, where many not closely related species were classified together. But as dinosaur fossil discoveries multiplied, Velociraptor i> was classified as a dromaeosaurid. All dromaeosaurids have been referred to the family Archeopterygidae by at least some author, which would, in effect, make Velociraptor a flightless bird. In the past, other dromaeosaurid species, including Deinonychus antirrhopus and Saurornitholestes langstoni, have sometimes been classified in the genus Velociraptor. Since Velociraptor was the first to be named, these species were renamed Velociraptor antirrhopus and Velociraptor langstoni, respectively. As of 2008, the only currently recognized species of Velociraptor are V. mongoliensis and V. osmolskae. However, several studies have found that V. osmolskae is distantly related to V. mongoliensis. If this turns out to be true, the species should be assigned to its own genus.
Phylogeny
The cladogram below follows a 2009 analysis by Longrich and Currie.
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The following are the results of the phylogeny of Eudromaeosauria based on the phylogenetic analysis carried out by James G. Napoli and his team in 2021 during the description of Kuru, showing the position of Velociraptor.
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Paleobiology
Predatory behavior
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The set of fossils known as the «fighting dinosaurs», found in 1971, preserves the remains of a Velociraptor and a Protoceratops apparently killed in combat, which provides direct evidence of predatory or predatory behavior. When the discovery of these fossils was published, it was thought that the two animals had drowned. However, as the remains were preserved in ancient aeolian deposits, they are now interpreted to have been buried in sand by a collapsing dune or in a sand storm. Both forelimbs and one hindlimb of the protoceratope are missing, indicating that it was carrion for other animals. Comparisons between the scleral rings of Velociraptor, Protoceratops and birds and reptiles Modern studies indicate that Velociraptor may have been nocturnal, while Protoceratops may have been cathemeral, active throughout the day at short intervals, suggesting that the fight may have occurred in twilight or low light conditions.
The distinctive hypertrophied claw, on the second digit of the dromaeosaurid claw-like foot, has traditionally been depicted as a slashing weapon, presumably used to cut and disembowel its prey. Fighting Dinosaurs,” Velociraptor is positioned below, its deadly claw seemingly embedded in its victim's throat, while the protoceratope's beak bites into and pins its attacker's right arm. This suggests that Velociraptor may have used its fingernail for precision killing by piercing vital organs, such as the jugular vein, carotid artery, or trachea, rather than ripping open the abdomen. Since the inner edge of the nail was rounded and not quite sharp, it could not have generated a type of ripping cut, making the nail more of a piercing than cutting weapon, although only the bony core of the nail is known. a; the keratin sheath may have had a sharper edge. However, it is unlikely that the edge could have been maintained, because the nail, as far as is known, could not be retracted to protect it. It also couldn't have been easy to scratch anything, a problem cats have too. This fact would indicate that the protoceratope's thick abdominal wall of skin and muscle would have been difficult to slash with such a blunt cutting surface. The slash hypothesis was examined in a 2005 BBC documentary The Truth About Killer Dinosaurs. The show's producers created an artificial Velociraptor claw with a sickle-shaped nail and used a pig's belly to simulate dinosaur prey. Although the nail penetrated the abdominal wall, it was unable to cut it open, indicating that the nail was not used to disentangle prey.
Deinonychus is a dromaeosaurid phylogenetically very close to Velociraptor, and deinonic remains have often been found in groups of several individuals. Deinonychus is also occasionally associated with a larger herbivore, Tenontosaurus, which has been interpreted as evidence of cooperative hunting. However, while many fossils have been discovered of Velociraptor and other dromaeosaurids in Mongolia, all have been isolated specimens and not in close proximity to each other. The only solid evidence of social behavior among dromaeosaurids comes from a footprint impression in China, which shows six individuals of a large species moving as a group, although no evidence of cooperative hunting has been found. No other dromaeosaurid groups have been found in close association.
In 2011, Denver Fowler et al. suggested a new method by which dromaeosaurids such as Velociraptor could have caught smaller prey. In this model, known as the 'raptor prey retention' (RPR) model of predation, they propose that dromaeosaurids killed their victims in much the same way as modern accipitrid birds of prey: by jumping on their prey, fixing it with its body weight, and holding it firmly with its large sickle-shaped claws. Like accipitrids, dromaeosaurids may have begun feeding on their prey while it was still alive, until it eventually died from blood loss and organ failure. This proposal is based primarily on comparisons between the morphology and proportions of the foot and legs of dromaeosaurids and various groups of extant predatory birds of prey. Fowler found that the foot and legs of these dinosaurs are very similar to those of eagles and hawks, especially in having a highly elongated second-toed claw and a similar range of grasping motion. The short tarsometatarsus and foot strength, however, might have been more similar to that of owls. The RPR method of predation could be consistent with other aspects of Velociraptor anatomy, such as its unusual jaw and arm morphology. The arms, which could have exerted considerable force and covered with long feathers, may have been used as stabilizers by flapping to balance while on top of struggling prey, along with the stiff counterbalancing tail. The jaws, which Fowler et al. consider comparatively weak, might have been useful for eating the prey alive, but not so useful for dispatching it swiftly and forcefully. These predatory adaptations working together may also have had implications for the origin of wing flapping in paravians.
Scavenging behavior
In 2010 Hone et al. published an article about their 2008 discovery of isolated teeth that they considered to be from Velociraptor along with bite marks on the bone of a suspected Protoceratops in the Bayan Mandahu Formation. The authors concluded that the find represented "the last stage of consumption of the carcass by Velociraptor", since when the predator had eaten other parts of a freshly killed Protoceratops, before biting in the jaw area. This observation was perceived as further evidence for the fossil-based inference of the "fighting dinosaurs" that Protoceratops was part of the Velociraptor diet. In 2012 Hone et al published a paper describing a Velociraptor specimen with a bone length of an azhdarchid pterosaur in its throat. This finding was interpreted as evidence of scavenging behavior.
Senses
Examinations of the Velociraptor endocranium indicate that it was able to detect and hear a wide range of sound frequencies, 2368–3965 Hz, and as a result was able to track prey with ease. Examinations of the endocranium also further cemented the theory that dromaeosaurids were agile and swift predators. Fossil evidence suggests that Velociraptor eating carrion also indicates that it was an opportunistic and actively predatory animal, feeding on carrion in times of drought or famine, if in poor health, or depending on the age of the animal.
Feathers
In 2007, Alan H. Turner and colleagues reported the presence of six bulges on the ulna of a specimen of Velociraptor, referred to as IGM 100/981, from the locality of Ukhaa Tolgod of the Djadochta Formation. Turner and his colleagues interpreted the presence of feathers in Velociraptor as evidence against the idea that larger, flightless maniraptorans lost their feathers secondarily due to larger body size. In addition, they noted that feather bumps are almost never found in flightless bird species today, and that their presence in Velociraptor, which is assumed to be flightless due to its relatively large size and their short forelimbs, is evidence that the ancestors of dromaeosaurids could fly. Which makes Velociraptor and other large members of this family secondarily flightless, although it is possible that the large wing feathers are inferred that the ancestors of Velociraptor had a purpose other than flight. The feathers of the flightless Velociraptor may have been used for display, to cover their nests while brooding, or for increased speed and thrust when running down steep slopes. Due to the presence of another dromaeosaurid on Ukhaa Tolgod, Tsaagan, Napoli and their team have noted that the reference of this specimen to Velociraptor is currently subject to revision.
Dromeosaurid species older than Velociraptor are known to have feathers on the body, fully developed on the arms. The fact that the ancestors of Velociraptor were feathered and with some flight ability suggests that Velociraptor also bore feathers, since even today's flightless birds retain much of their plumage. In September 2007, Turner, Makovicky and Norell published that the ulna, one of the arm bones, of a Velociraptor found in Mongolia shows typical protuberances from the insertion of feather cannons. These protuberances in the wing bones of birds they show where the feathers are attached, and their presence in Velociraptor indicates that this dinosaur also had them. According to paleontologist Alan Turner,
Lack of cannon bonds does not necessarily mean that a dinosaur does not have feathers. Find them in VelociraptorHowever, it means he definitely had feathers. This is something we suspected a long time ago, but we hadn't been able to check it out.
Another of the paper's co-authors, Mark Norell, curator in charge of fossil reptiles, amphibians, and birds at the American Museum of Natural History, also commented on their discovery, saying:
The more we learn about these animals, the more we find that there is practically no difference between the birds and the dinosaurs more closely related to their ancestors as Velociraptor. Both have spurs, packed their nests, have hollow bones and were covered with feathers. If animals like Velociraptor were alive today our first impression would be that they were only birds of very unusual appearance.
According to Turner, Makovicky, and Norell, the protrusions that hold the feathers are not present in all prehistoric birds, but their absence does not mean that the animal was not feathered—flamingos, for example, lack such protrusions—. However, its presence confirms that Velociraptor had modern-looking wing feathers, with a rachis and a vane formed by wattles. The forearm specimen on which the bumps were found (specimen number IGM 100/981) represents an animal 1.5 meters long and fifteen kilograms in weight. Based on the spaces between the six bulges preserved in this specimen, the authors suggested that Velociraptor had fourteen secondary feathers (wing feathers coming from the forearm), compared to twelve or more in Archaeopteryx, eighteen in Microraptor and ten in Rahonavis. This kind of variation in the number of wing feathers between closely related species is somewhat to be expected, the authors say, since similar variation occurs among modern birds.
Turner and colleagues interpreted the presence of feathers in Velociraptor as evidence against the idea that large flightless dinosaurs of the taxon Maniraptora lost their feathers from secondary form due to its larger size. Furthermore, they noted that the bumps are almost never found in today's flightless birds, and their presence in Velociraptor (which must have been terrestrial due to its relatively large size and short arms) is proof that dromaeosaurid ancestors could fly, which would make Velociraptor and other large members of its family secondarily terrestrial, although it is possible that the long wing feathers inferred in Velociraptor's ancestors served a purpose other than flight. The flightless Velociraptor's feathers may have been used for display, covering its nests while brooding, or to add speed and momentum when running up steep inclines.
Food
In 2020, Powers and colleagues re-examined the jaws of several eudromaeosaurid taxa and concluded that most Asian and North American were separated by snout morphology and ecological strategies. They found that the maxilla was a reliable reference when inferring the shape of the premaxilla and the snout in general. For example, most Asian species have elongated jaw-based snouts, ie velociraptorines, indicating selective feeding in Velociraptor and relatives, such as picking up small, fast prey. By contrast, most North American eudromaeosaurids, mostly dromaeosaurs, have a robust and deep maxillary morphology. However, the large dromaeosaurid Achillobator is a unique exception to Asian taxa with its deep jawbone.
Metabolism
The fact that Velociraptor was covered in feathers suggests that it was homeothermic (warm-blooded), since an insulating cover only makes sense in animals that need to maintain their body heat and would be a nuisance for an animal that had to warm itself in the sun. We can verify this in modern animals that have feathered or furry "coats", as Velociraptor could have had, which are only warm-blooded. This also means that you should need significant amounts of meat to maintain your metabolism. However, the range of bone growth in dromaeosaurids and some primitive birds suggests a more moderate metabolism, compared to most modern warm-blooded mammals and birds. Kiwis are similar to dromaeosaurids in anatomy, covered in feathers, bone structure, and even the narrow shape of the sinuses (usually a good indicator of metabolism). Kiwis are highly active, specialized, flightless birds, with a stable body temperature and a fairly low resting metabolic rate, being a good example of primitive bird and dromaeosaurid metabolism.
Pathology
In 1995, Norell and colleagues reported a Velociraptor mongoliensis skull that has two parallel rows of small perforations in its frontal bones that, upon closer examination, match the size and spacing of Velociraptor teeth. Scientists believe the wound was probably inflicted by another Velociraptor during a fight. In fact, since the fossil bone shows no signs of healing around the bite wounds, this injury probably killed it. In 2001, Molnar and his team observed that this specimen is MPC-D 100/976 , from the town of Tugrik Shireh, which also contributed the specimen "Fighting Dinosaurs".
In 2012, David Hone and his team reported that another injured Velociraptor specimen, MPC-D 100/54, approximately a subadult individual, had encountered the bones of an azhdarchid pterosaur inside its stomach cavity, was carrying or recovering from a rib injury. Based on evidence in pterosaur bones, which lacked pitting or digestion deformation, Velociraptor died shortly thereafter, possibly due to earlier injury. However, the team noted that these broken ribs show signs of bone healing.
Paleoecology
Provenance
Djadochta Formation
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All known specimens of V. mongoliensis have been discovered in the Djadochta Formation, or Djadokhta, in Ömnögovi Province, Mongolia, or in the Chinese area of Inner Mongolia. A species of Velociraptor, possibly V. mongoliensis, has been discovered in the Barun Goyot Massif, Mongolia, which is a somewhat younger formation, although it could equally belong to a new, undetermined genus. These geological formations are estimated to date from the Campanian epoch., about 83 to 70 million years ago. Late Cretaceous. The abundant sediments, sands, sandstones, or caliche of the Djadochta Formation were deposited by aeolian processes in arid environments with sand dune fields and only intermittent streams, as indicates fluvial sedimentation, deposited in rivers, very scarce, in a semi-arid climate.
The Djadochta Formation is separated into a lower Bayn Dzak member and an upper Turgrugyin member. V. mongoliensis is known from both members, represented by numerous specimens. The Bayn Dzak Member, primarily the Bayn Dzak locality, has produced the oviraptorid Oviraptor philoceratops, the ankylosaurid Pinacosaurus grangeri, protoceratopsid Protoceratops andrewsi and the troodontid Saurornithoides. The youngest member of the Turgrugyi, mainly the Tugriken Shireh locality, has produced the bird Elsornis, the dromaeosaurid Mahakala omnogovae, the ornithomimid Aepyornithomimus tugrikinensis and the protoceratopsid Protoceratops andrewsi.
Specimens of V. mongoliensis in many of the areas of Djadochta. The type specimen was discovered in the area called the Blazing Cliffs, also known as Bayn Dzak and Shabarakh Usu, while the "fighting dinosaurs" were found in the town of Tugrig, also known as Tugrugeen Shireh. The well-known Barun Goyot localities of Khulsan and Khermeen Tsav have also yielded remains that may be of Velociraptor or a related genus. A dromaeosaurid skull, identified as IGM 100/1015, was excavated in Ukhaa Tolgod, and could be from a new species of Velociraptor. In the localities of Khulsan and Khermeen Tsav in Barun Goyot, remains that could belong to the genus Velociraptor. Fossils of V. mongoliensis from Bayan Mandahu, a prolific fossil bed site, in Djadochta of Inner Mongolia. However, these fossils had not been prepared or studied until 2008. A partial skull of an adult from the Bayan Mandahu Formation it has been assigned to a separate species, Velociraptor osmolskae.
Bayan Mandahu Formation
In the Bayan Mandahu formations, where V. osmolskae, and Djadochta many of the same genera were present, although they varied at species level. These differences in species composition may be due to a natural barrier separating the two formations, which are relatively close to each other geographically. However, given the lack of any known barrier that could cause the specific faunal compositions to be found in these areas, those differences are more likely to indicate a slight time difference.
V. osmolskae lived alongside the ankylosaurid Pinacosaurus mephistocephalus, the alvarezsaurid Linhenykus monodactylus, the closely related dromaeosaurid Linheraptor exquisitus, the oviraptorids Machairasaurus leptonychus and Wulatelong gobiensis, the protoceratopsids Bagaceratops rozhdestvenskyi and Protoceratops hellenikorhinus and the troodontids Linhevenator tani, Papiliovenator neimengguensis and Philovenator curriei. Sediments throughout the formation indicate a depositional environment similar to that of the Djadochta Formation.
Habitat
All of these sites had an arid climate, with sand dune fields and intermittent streams. However, existing evidence would indicate that the climate at Barun Goyot was wetter than at Djadochta.
The deposits in which Velociraptor has been found give a good idea of what the landscape or habitat in which it lived might have been. The sites in Djadochta show an arid environment with numerous deserts and sand dunes in which dense forests grew, crossed by intermittent streams or ravines. Normally in habitats like these, Velociraptor is usually found. However, other more recent deposits in Barun Goyot, in which there are also remains of the Velociraptor, show a slightly more humid climate, which indicates that around the Campanian epoch the climate and environment of Velociraptor had slight changes. The posture of some complete fossils, as well as the mode of preservation, show that they were within unstructured sandstone deposits, indicating that a number of specimens were buried alive during sandstorms, common events in these environments.
Many of the same genera were present in these formations, although they varied at the species level. For example, Djadochta was home to Velociraptor mongoliensis, Protoceratops andrewsi and Pinacosaurus grangeri, while Bayan Mandahu was home to Velociraptor osmolskae, Protoceratops hellenikorhinus and Pinacosaurus mephistocephalus. These differences in species composition may be due to a natural barrier separating the two formations, which are relatively close geographically. However, given the lack of any known barrier that could cause endemism in the faunas of these areas, it is these differences are more likely to indicate a slight temporal difference.
Other known dinosaurs from the same localities as V. mongoliensis include the primitive bird Judinornis, the troodontid Saurornithoides, the oviraptorid Oviraptor, and the primitive dromaeosaurid Mahakala i>, in addition to the mammals Deltatheridium and Zalambdalestes. V. osmolskae lived alongside the ceratopsian Magnirostris, as well as the oviraptorid Machairasaurus and the dromaeosaurid Linheraptor.
In popular culture
Velociraptor is best known for his role as a cruel and cunning assassin in the 1990 novel Jurassic Park, by Michael Crichton, and its subsequent 1993 film adaptation, Directed by Steven Spielberg. The "raptors" that appeared in Jurassic Park were designed to represent their 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 the Deinonychus fossils would have been found, far from the Central Asian area proper to Velociraptor. A character in Crichton's novel clarifies this: "The Deinonychus is now considered to be one of the Velociraptor", indicating that Crichton used the taxonomy proposed by Gregory Paul in 1988. However, "raptors" in the novel referred to Velociraptor mongoliensis. Crichton met the discoverer of Deinonychus, John Ostrom, several times at the University of Yale to discuss the details of the animal's possible range of behaviors and appearance. Crichton at one point told Ostrom apologetically that he had decided to use the name Velociraptor instead of Deinonychus because the earlier name was "more dramatic" # 3. 4;. According to Ostrom, Crichton claimed that the Velociraptor in the novel was based on Deinonychus in almost every detail, with only the name changed. The Jurassic Park filmmakers also requested all of Ostrom's published articles on Deinonychus during production. They portrayed the animals with Deinonychus size, proportions, and snout shape. > instead of Velociraptor.
Production on Jurassic Park began before the discovery of the large dromaeosaurid Utahraptor was made public in 1991, but as Jody Duncan wrote of this discovery: "Later, after we designed and built the raptor, a raptor skeleton was discovered in Utah, which they called a 'super-slasher'. They had discovered the largest Velociraptor to date and it was 1.65 meters tall, just like ours. So we designed it, we built it, and then they figured it out. That still amazes me". Spielberg's name was briefly considered to name the new dinosaur in exchange for funding the fieldwork, but no agreement was reached.
The Velociraptors depicted in the Jurassic Park movies were scientifically inaccurate in a number of 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 larger than its diminutive counterparts. real. The size of Velociraptor in the film may also have been increased for dramatic reasons by director Steven Spielberg.
In the movie versions, Velociraptors were also covered in scales. There is no evidence of body scales reported on any dinosaur in the Maniraptora clade and it is more likely that this one was covered with feathers. In Jurassic Park III, feather-like structures appear on the back of the head and neck, although these do not resemble the feathers known from dromaeosaurids in real life. Additionally, the forelimbs of the filmed animals do not resemble those of real dromaeosaurids and their tails were very short and flexible, errors in anatomy that directly contradict fossil evidence. In the movie Jurassic Park III, one of the characters further indicates that Velociraptors were more intelligent than dolphins, whales and primates. Based on the fossil record, this is highly doubtful, and it is more likely that, while they were intelligent compared to other dinosaurs, they were less intelligent than modern big cats. However, the dromaeosaur Pyroraptor was feathered. for Jurassic World Dominion, along with other changes such as stiffening the tail to account for ossified tendons, and deproning the hands.