Velociraptor (; ) is a genus of small dromaeosaurid dinosaurs that lived in Asia during the Late Cretaceous epoch, about 75 million to 71 million years ago (Mya). Two species are currently recognized, although others have been assigned in the past. The type species is V. mongoliensis, named and described in 1924. Fossils of this species have been discovered in the Djadochta Formation, Mongolia. A second species, V. osmolskae, was named in 2008 for skull material from the Bayan Mandahu Formation, China. A possible record is known from the Nemegt Formation.
Smaller than other dromaeosaurids like Deinonychus and Achillobator, Velociraptor was about long with a body mass of around . It nevertheless shared many of the same anatomical features. It was a bipedal, feathered carnivore with a long tail and an enlarged sickle-shaped claw on each hindfoot, which is thought to have been used to tackle and restrain prey. Velociraptor can be distinguished from other dromaeosaurids by its long and low skull, with an upturned snout.
Velociraptor (commonly referred to as "raptor") is one of the dinosaur genera most familiar to the general public due to its prominent role in the Jurassic Park films. In reality, Velociraptor was roughly the size of a turkey, considerably smaller than the approximately 2 m (6.6 ft) long and reptiles seen in the novels and films (which were based on members of the related genus Deinonychus). Today, Velociraptor is well known to paleontologists, with over a dozen described fossil skeletons. One particularly famous specimen preserves a Velociraptor locked in combat with a Protoceratops.
History of discovery
During an American Museum of Natural History expedition to the Flaming Cliffs (Bayn Dzak or Bayanzag) of the Djadochta Formation, Gobi Desert, on 11 August 1923, Peter Kaisen discovered the first Velociraptor fossil known to science—a crushed but complete skull, associated with one manual claw and adjoining phalanges (AMNH 6515). In 1924, museum president Henry Fairfield Osborn designated the skull and part of the manus as the type specimen of his new genus, Velociraptor. This name is derived from the Latin words ('swift') and ('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. Earlier that year, Osborn had informally mentioned the animal in a popular press article, under the name "Ovoraptor djadochtari" (not to be confused with the similarly named Oviraptor), eventually changed into V. mongoliensis during its formal description.
While North American teams were shut out of communist 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 "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 New York City for a temporary exhibition.
Between 1988 and 1990, a joint Chinese-Canadian team discovered Velociraptor remains in northern China. American scientists returned to Mongolia in 1990, and a joint Mongolian-American expedition to the Gobi, led by the American Museum of Natural History and the Mongolian Academy of Sciences, turned up several well-preserved skeletons. One such specimen, MPC-D 100/980, was nicknamed "Ichabodcraniosaurus" by Norell's team because the fairly complete specimen was found without its skull (an allusion to the Washington Irving character Ichabod Crane).Novacek, Michael J. (1996). Dinosaurs of the Flaming Cliffs. New York: Anchor Books. . While Norell and Makovicky provisionally considered it a specimen of Velociraptor mongoliensis, it was named as a new species Shri devi in 2021.
In 1999, Rinchen Barsbold and Halszka Osmólska reported a juvenile Velociraptor specimen (GIN or IGM 100/2000), represented by a complete skeleton including the skull of a young individual. It was found at the Tugriken Shireh locality of the Djadochta Formation during the context of the Mongolian-Japanese Palaeontological Expeditions. The coauthors stated that detailed descriptions of this and other specimens would be published at a later date.
Additional species
Maxillae and a lacrimal (the main tooth-bearing bones of the upper jaw, and the bone that forms the anterior margin of the eye socket, respectively) recovered from the Bayan Mandahu Formation in 1999 by the Sino-Belgian Dinosaur Expeditions were found to pertain to Velociraptor, but not to the type species V. mongoliensis. Pascal Godefroit and colleagues named these bones V. osmolskae (for Polish paleontologist Halszka Osmólska) in 2008. However, the 2013 study noted that while "the elongate shape of the maxilla in V. osmolskae is similar to that of V. mongoliensis," phylogenetic analysis found it to be closer to Linheraptor, making the genus paraphyletic; thus, V. osmolskae might not actually belong to the genus Velociraptor and requires reassessment.
Paleontologists Mark A. Norell and Peter J. Makovicky in 1997 described new and well preserved specimens of V. mongoliensis, namely MPC-D 100/985 collected from the Tugrik Shireh locality in 1993, and MPC-D 100/986 collected in 1993 from the Chimney Buttes locality. The team briefly mentioned another specimen, MPC-D 100/982, which by the time of this publication remained undescribed. In 1999 Norell and Makovicky provided more insights into the anatomy of Velociraptor with additional specimens. Among these, MPC-D 100/982 was partially described and figured, and referred to V. mongoliensis mainly based on cranial similarities with the holotype skull, although they stated that differences were present 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 (specifically at the "Volcano" sub-locality). Martin Kundrát in a 2004 abstract compared the neurocranium of MPC-D 100/982 to another Velociraptor specimen, MPC-D 100/976. He concluded that the overall morphology of the former was more derived (advanced) than the latter, suggesting that they could represent distinct taxa.
Mark J. Powers in his 2020 master thesis fully described MPC-D 100/982, which he concluded to represent a new and third species of Velociraptor. This species, which he considered distinct, was stated to mainly differ from other Velociraptor species in having a shallow maxilla morphology. Powers and colleagues also in 2020 used morphometric analyses to compare several dromaeosaurid maxillae, and found the maxilla of MPC-D 100/982 to strongly differ from specimens referred to Velociraptor. They indicated that this specimen, based on these results, represents a different species. In 2021 Powers with team used Principal Component Analysis to separate dromaeosaurid maxillae, most notably finding that MPC-D 100/982 falls outside the instraspecific variability of V. mongoliensis, arguing for a distinct species. They considered that both V. mongoliensis and this new species were ecologically separated based on their skull anatomy. The team in another 2021 abstract reinforced again the species-level separation, noting that additional differences can be found in the hindlimbs.
Description
Velociraptor was a small to medium-sized dromaeosaurid, with adults measuring between long, approximately high at the hips, Supporting Online Material and weighing about .Supporting Information Some estimates suggest that Velociraptor may have been larger, possibly reaching lengths of about 2.5 m (8 ft) and weighing up to 28 kg (60 lb).
Prominent quill knobs—attachment site of "wing" feathers and direct indicator of a feather covering—have been reported from the ulna of a single Velociraptor specimen (IGM 100/981), which represents an animal of estimated long and in weight. The spacing of 6 preserved knobs suggests that 8 additional knobs may have been present, giving a total of 14 quill knobs that developed large secondaries ("wing" feathers stemming from the forearm). However, the specimen number has been corrected to IGM 100/3503 and its referral to Velociraptor may require reevaluation, pending further study. Nevertheless, there is strong phylogenetic evidence from other dromaeosaurid relatives that indicates the presence of feathers in Velociraptor, including dromaeosaurids such as Daurlong, Microraptor, or Zhenyuanlong.
Skull
The skull of Velociraptor was rather elongated and grew up to long. It was uniquely up-curved at the snout region, concave on the upper surface, and convex on the lower surface. The snout, which occupied about 60% of the entire skull length, was notably narrow and mainly formed by the nasal, premaxilla, and maxilla bones. The was the anteriormost bone in the skull, and it was longer than taller. While its posterior end joined the nasal, the main body of the premaxilla touched the maxilla. The was nearly triangular in shape and the largest element of the snout. On its center or main body, there was a depression developing a small oval to circular-shaped hole, called maxillary fenestra. Though in front of this fenestra were two small openings, referred to as promaxillary fenestrae. The posterior border of the maxilla formed (predominantly) the antorbital fenestra, one of the several large holes in the skull. Both premaxilla and maxilla had several alveoli (tooth sockets) on their bottom surfaces. Above the maxilla and making contact with the premaxilla, there was the bone. It was a thin/narrow and elongated bone contributing to the top surface of the snout. Together, both premaxilla and nasal bones gave form to the naris or narial fenestra (nostril opening), which was relatively large and circular. The posterior end of the nasal was joined by the frontal and lacrimal bones.
The back or posterior region of the skull was built by the frontal, lacrimal, postorbital, jugal, parietal, quadrate, and quadratojugal bones. The was large element, having a vaguely rectangular shape when seen from above. On its posterior end, this bone was in contact with the , and such elements were the main bodies of the skull roof. The was a T-shaped bone and its main body was thin and delicated. Its lower end meet the (often called cheek bone), which was a large, sub-triangular-shaped element. Its lower border was notably straight/horizontal. The was located just above the jugal: a stocky and strongly T-shaped bone. As a whole, the orbit or orbital fenestra (eye socket)—formed by the lacrimal, jugal, frontal, and postorbital—was large and near circular in shape, being longer than taller. When seen from above, a pair of large and markedly rounded holes were present near the rear of the skull (the temporal fenestrae), whose main components were the postorbital and squamosal. Behind the jugal, an inverted T-shaped bone (also seen in other dromaeosaurids), known as the , was developed. While the upper end of the quadratojugal joined the , an irregularly-shaped element, its inner side meet the . The latter was of great importance for the articulation with the lower jaw. The posteriormost bone was the and its projection the occipital condyle: a rounded and bulbous protuberance that meet the first vertebra of the neck.