Deinonychus (/daɪˈnɒnɪkəs/[1]dy-NON-ih-kəs; from Ancient Greek δεινός (deinós) 'terrible', and ὄνυξ (ónux), genitive ὄνυχος (ónukhos) 'claw') is a genus of dromaeosaurid theropod dinosaur with one described species, Deinonychus antirrhopus. This species, which could grow up to 3.4 meters (11 ft) long, lived during the early Cretaceous Period, about 115–108 million years ago (from the mid-Aptian to early Albian stages). Fossils have been recovered from the U.S. states of Montana, Utah, Wyoming, and Oklahoma, in rocks of the Cloverly Formation and Antlers Formation, though teeth that may belong to Deinonychus have been found much farther east in Maryland.
Paleontologist John Ostrom's study of Deinonychus in the late 1960s revolutionized the way scientists thought about dinosaurs, leading to the "dinosaur renaissance" and igniting the debate on whether dinosaurs were warm-blooded or cold-blooded. Before this, the popular conception of dinosaurs had been one of plodding, reptilian giants. Ostrom noted the small body, sleek, horizontal posture, ratite-like spine, and especially the enlarged raptorial claws on the feet, which suggested an active, agile predator.[2]
"Terrible claw" refers to the unusually large, sickle-shaped talon on the second toe of each hind foot. The fossil YPM 5205 preserves a large, strongly curved ungual. In life, archosaurs have a horny sheath over this bone, which extends the length. Ostrom looked at crocodile and bird claws and reconstructed the claw for YPM 5205 as over 120 millimetres (4.7 in) long.[2] The species name antirrhopus means "counter balance", which refers to Ostrom's idea about the function of the tail. As in other dromaeosaurids, the tail vertebrae have a series of ossified tendons and super-elongated bone processes. These features seemed to make the tail into a stiff counterbalance, but a fossil of the very closely related Velociraptor mongoliensis (IGM 100/986) has an articulated tail skeleton that is curved laterally in a long S-shape. This suggests that, in life, the tail could bend to the sides with a high degree of flexibility.[3] In both the Cloverly and Antlers formations, Deinonychus remains have been found closely associated with those of the ornithopod Tenontosaurus. Teeth discovered associated with Tenontosaurus specimens imply they were hunted, or at least scavenged upon, by Deinonychus.
^ abOstrom, John Harold (1970). "Stratigraphy and paleontology of the Cloverly Formation (Lower Cretaceous) of the Bighorn Basin area, Wyoming and Montana". Bulletin of the Peabody Museum of Natural History. 35: 1–234.
^Norell, Mark A.; Makovicky, Peter J. (1999). "Important features of the dromaeosaurid skeleton II: information from newly collected specimens of Velociraptor mongoliensis". American Museum Novitates (3282): 1–45. hdl:2246/3025.
teeth that may belong to Deinonychus have been found much farther east in Maryland. Paleontologist John Ostrom's study of Deinonychus in the late 1960s revolutionized...
prey. Remains of Deinonychus, a closely related dromaeosaurid, have commonly been found in aggregations of several individuals. Deinonychus has also been...
Velociraptor, Deinonychus, and Saurornitholestes, and while the discovery of Tsaagan lent support to this grouping, the inclusion of Deinonychus, Saurornitholestes...
name, ostrommaysi, is in honor to John Ostrom for his investigations on Deinonychus and its relationships to birds, as well as Chris Mays, who helped in...
contain Deinonychus remains. According to one 1995 study, only six sites containing Deinonychus fossils contain no trace of Tenontosaurus, and Deinonychus remains...
of Deinonychus in 1964, Ostrom challenged the widespread belief that dinosaurs were slow-moving lizards (or "saurians"). He argued that Deinonychus, a...
labeled Deinonychus as a Velociraptor species due to Paul's belief that many dinosaur genera should be combined. John Ostrom, who discovered Deinonychus, was...
velociraptorines are probably Nuthetes from the United Kingdom, and possibly Deinonychus from North America. However, several indeterminate velociraptorines have...
Utahraptor, but more closely resembles smaller dromaeosaurids, like Deinonychus. Apart from its large size, the description of 2015 indicated some additional...
Dromaeosaurus shared many features with Velociraptor and the newly discovered Deinonychus, and assigned these forms to a new family: Dromaeosauridae. Since then...
birds than to Deinonychus", with Troodon being sometimes added as a second external specifier in case it is closer to birds than to Deinonychus. Avialae is...
(including Tyrannosaurus), the dromaeosaurids (including Velociraptor and Deinonychus, which are remarkably similar in form to the oldest known bird, Archaeopteryx)...
most inclusive natural group containing Dromaeosaurus, Velociraptor, Deinonychus, and Saurornitholestes, their most recent common ancestor and all of...
First, John Ostrom discovered the bird-like dromaeosaurid theropod Deinonychus and described it in 1969. Its anatomy indicated that it was an active...
discovered that has tooth drag marks attributed to Saurornitholestes. Deinonychus, along with other similar dromaeosaurs, were suggested to kill prey in...
although Deinonychus may have done so. Skeletal remains from subadults with missing parts are suspected of having been eaten by other Deinonychus, mainly...
most inclusive natural group containing Dromaeosaurus, Velociraptor, Deinonychus, and Saurornitholestes, their most recent common ancestor and all of...
Velociraptorinae, such as Longrich and Currie in 2009, which recovered Deinonychus outside of the Velociraptorine and Dromaeosaurinae. Traditionally, Adasaurus...
theory of bird evolution from dinosaurs after his 1964 discovery of Deinonychus in Wyoming, agreed, calling the specimen a "jewel", and telling reporters...
without a predatory Deinonychus in sight (Tenontosaurus is almost exclusively depicted in dinosaur art as the prey of Deinonychus). The second and last...
unlike most other velociraptorines, and similar to Dromaeosaurus and Deinonychus. It preserved 14 (or possibly 15) tooth positions, which is much higher...
dinosaur in Montana. In 1969, this dinosaur was described and named Deinonychus by John Ostrom of Yale University. The next year, Ostrom redescribed...
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