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Velociraptor

Velociraptor, meaning “swift seizer” is a genus of dromaeosaurid theropod dinosaur that lived about 75 to 71 million years ago during the later part of the Cretaceous Period. There are two species that are presently recognized. The type species is V. mongoliensis; fossils of this particular species have been uncovered in Mongolia. A second species, V. osmolskae, it was named in 2008 for some skull material from Inner Mongolia, China.

They are smaller than other dromaeosaurids such as Deinonychus and Achillobator, though they shared many of the same anatomical features. It was a bipedal carnivore bearing feathers with a long tail and an enlarged sickle-shaped claw on each hind food, which is considered to have been used to kill its prey. Velociraptor can be distinguished from other dromaeosaurids by its low and long skull and upturned snout.

It was a mid-sized dromaeosaurid, the adults measuring up to 6.8 ft long, 1.6 ft high at the hip, and weighing up to 33 lb. The skull, which grew up to 9.8 inches long, was distinctively up-curved, the upper surface being concave and the lower surface being convex. The jaws were lined with about 26 to 28 teeth, widely spaced, on each side, each more strongly jagged on the back edges than the front.

Like other dromaeosaurids, Velociraptor had a large manus, meaning hand, with three strongly curved claws, which were much like the wing bones of modern birds in regards to construction and flexibility. The second digit was the longest of the three, while the first was the shortest. The first digit of the foot, like in other theropods, was a small dewclaw. However, where as most theropods had feet with three digits making contact with the ground, dromaeosaurids such as the Velociraptor, walked only on their third and fourth digits. The second digit was highly modified and held retracted off the ground. It bore a somewhat large, sickle-shaped claw, which is usual of dromaeosaurid and troodontid dinosaurs. This oversized claw, which could be over 2.6 inches long around its outer edge, was probably a device used in predation, aiding in tearing into the prey, potentially delivering a fatal blow. In 2007, some paleontologists documented the discovery of quill knobs on a very well-preserved Velociraptor mongoliensis forearm from Mongolia, authenticating the presence of feathers in this species.

On August 11, 1923, Peter Kaisen uncovered the first Velociraptor fossil known to science during an American Museum of Natural History expedition to the Outer Mongolian Gobi Desert. It consisted of a crushed, but complete skull, associated with one of the raptorial second toe claws. In 1924, museum president Henry Fairfield Osborn designated these fossils 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 is in reference to the animals cursorial nature and its carnivorous diet.

All of the sites that produced Velociraptor remains preserve an arid environment with fields of sand dunes and only sporadic streams. The posture of some complete fossils, in addition to the mode of preservation most show in structure less sandstone deposits, might show that numerous specimens were buried alive during sandstorm events that were frequent to the three environments.

Velociraptor belongs to the subfamily Velociraptorinae, a resulting subgroup of the larger family called Dromaeosauridae. In phylogenetic taxonomy, Velociraptorinae is generally defined as “all dromaeosaurs more closely related to Velociraptor than to Dromaeosaurus”. When it was initially described in 1924, Velociraptor was put in the family Megalosauridae, which was the case with most carnivorous dinosaurs at that time. As discoveries multiplied, Velociraptor was later recognized as a dromaeosaurid.

The specimen called “Fighting Dinosaurs”, found in 1971, preserves a Velociraptor mongoliensis and Protoceratops andrewsi in combat and gives direct evidence of predatory behavior. When it was initially reported, it was thought that the two animals drowned. However, as the animals were preserved in ancient sand dune deposits, it’s now though that the animals were buried in sand, either from the collapsing of a dune or in a sandstorm. The life like poses that the animals were preserved it suggests that the burial was quite rapid.

In 2012, Hone and colleagues released a paper regarding their 2008 discovery of shed teeth belonging to what they believed to be a Velociraptor near a tooth-marked jaw bone of what they though to be a Protoceratops in the Bayan Mandahu Formation. Authors concluded that the find was in representation of “late-stage carcass consumption by Velociraptor” as the predator would’ve eaten other parts of a freshly killed Protoceratops before biting into the area of the jaw.

It was most likely warm-blooded to some extent, as it needed a significant amount of energy to hunt. Some modern animals that have feathery or furry coats, as the Velociraptor did, tend to be warm-blooded, since these coverings serve as insulation. However, bone growth rates in dromaeosaurids and some early birds propose a more moderate metabolism, compared to most modern warm-blooded mammals and birds.

Image Caption: 148 Wyoming Dinosaur Center. Credit: Ben Townsend/Wikipedia (CC BY 2.0)

Velociraptor


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