Deinonychus antirrhopus
Deinonychus antirrhopus (Gr. "Terrible claw with counterweight") is the only species of the extinct genus Deinonychus a dromaeosaurid coelurosaurian dinosaur, which lived about 115 to 108 million years ago between the Aptian and Albian to mid-Cretaceous periods, in what is now North America. This species could grow up to 3.4 meters long. Fossils have been recovered from the US states of Montana, Utah, Wyoming, and Oklahoma, in rocks from the Cloverly Formation, Cedar Mountain Formation, and Antlers Formation, although teeth that may belong to Deinonychus have been found much further east, in Maryland.
Palaeontologist John Ostrom's study of Deinonychus in the late 1960s revolutionized the way scientists thought about dinosaurs, leading to the "dinosaur renaissance& #3. 4; and started the debate about whether dinosaurs were warm-blooded or cold-blooded. Prior to this, the popular conception of dinosaurs had been that of giant, plodding reptiles. Ostrom observed the small, elegant body, with a horizontal posture, a strucioniform spine, and especially the enlarged predatory claws on the feet, suggesting an agile and active predator.
The meaning of the genus name, "Terrible Claw," refers to the unusually large, sickle-shaped claw on the second toe of each hind foot. The fossil YPM 5205 preserves a large, strongly curved nail claw. In life, archosaurs had a horn sheath over this bone, extending its length. Ostrom observed crocodile and bird claws and reconstructed the claw for YPM 5205 over 120 millimeters long. The species name antirrhopus means "counterweight" 34;, which refers to Ostrom's idea of the function of the tail. As in other dromaeosaurids, the tail vertebrae have a series of ossified tendons and super-elongated processes on the vertebrae. These features suggest that the tail is a rigid counterweight, but a very closely related Velociraptor mongoliensis fossil, specimen IGM 100/986 has an articulated tail skeleton that is curved laterally in the shape of a long S. This suggests that, in life, the tail could be bent sideways with a high degree of flexibility. In both the Cloverly and Antlers formations, remains of Deinonychus have been found closely associated with those of the Antlers. ornithopod Tenontosaurus. The discovered teeth associated with Tenontosaurus specimens imply that they were hunted, or at least part of the scavenger diet, of Deinonychus.
Description
Based on the few fully mature specimens, Deinonychus could reach 3.4 meters in length, with a skull of around 410 millimeters, a height of 87 centimeters at the hips, and a weight of 73 kilograms although there are higher estimates of up to 100 kg.
Skull
The skull was equipped with powerful jaws rimmed with around seventy curved blade-like teeth. Skull studies have progressed a lot during the last decades. Ostrom reconstructed it from partial, imperfectly preserved specimens, describing it as triangular, broad, and quite similar to Allosaurus. Additional material from the Deinonychus skull and closely related genera found with good three-dimensional preservation show that the palate was more vaulted making it narrower than Ostrom thought, making the snout narrower, while the jugal expanded laterally, giving greater stereoscopic vision. The skull of Deinonychus was different in shape from that of Velociraptor, with a cranial vault like that of Dromaeosaurus, and it did not have the depressed nasals of Velociraptor. Both the skull and lower jaw had fenestrae, skull openings, which reduced the weight of the skull. In Deinonychus the antorbital window, an opening in the skull between the eye and the nostrils, were particularly large.
Limbs
Deinonychus had large "hands" with three claws on each forelimb. The first digit was shorter and the second was longer. Each hind foot bore a sickle-shaped claw on the second digit, which was probably used during predation.
Feather lining
No skin impressions have ever been found in association with Deinonychus fossils. However, evidence suggests that the Dromaeosauridae, including Deinonychus, had feathers. The genus Microraptor is both phylogenetically more primitive and geologically older. than Deinonychus, despite being in the same family. Multiple Microraptor fossils preserve pennaceous feathers, that is, feathers with blades like those of modern birds on the arms, legs, and tail, along with cloak and contour feathers. Velociraptor is geologically younger than Deinonychus, but is still more closely related, within the subfamily Velociraptorinae, as explained below. One Velociraptor specimen has been found with feather attachment knobs on the ulna. The attachment knobs are where the follicular ligaments meet, and are a direct indicator of modern-looking feathers.
Discovery and research
Fossilized remains of Deinonychus have been recovered from the Cloverly Formation of Montana and Wyoming and the Antlers Formation of Oklahoma in North America. The Cloverly Formation has been dated to the Late Aptian by reference to the early Albian stages of the Early Cretaceous, around 115 to 108 Ma. Additionally, teeth found in the clay layers of the middle Aptian and Potomac Formation on the Atlantic coastal plain of Maryland may be assigned to this genus.
Initial Findings
The first remains to be found were found in 1931 in southeastern Montana near the town of Billings. A group led by paleontologist Barnum Brown focused primarily on excavating and preparing the remains of the ornithopod Tenontosaurus, but in their field report on the excavation site for the American Museum of Natural History, they reported the discovery of a small carnivorous dinosaur near the Tenontosaurus skeleton, "but deeply embedded in the rock making it difficult to prepare". Brown informally named the animal "Daptosaurus agilis" and made preparations to describe it and placed it on display, under catalog number AMNH 3015, but this work was never completed. B. Brown later returned from the Cloverly Formation with the skeleton of one more theropod. small with apparently large teeth, which he informally named as "Megadontosaurus". John Ostrom revised the material several decades later, identifying the teeth as belonging to Deinonychus and the skeleton as coming from a totally different animal which he named Microvenator .
Discovery and description
A little over thirty years later, in August 1964, paleontologist John Ostrom led an expedition from Yale University's Peabody Museum that discovered more skeletal material. Expeditions over the next two summers unearthed more than 1,000 bones, including at least three individuals. Since the association between the various bones recovered was weak, it was impossible to determine the exact number of individual animals, the type specimen, YPM 5205, from Deinonychus was restricted to a complete left foot and a partial right foot that definitely belonged to the same individual. The remaining specimens were cataloged in fifty separate entries in the Yale Peabody Museum of Natural History.
Subsequent studies by Ostrom and Meyer analyzed their own material as well as the "Daptosaurus" of B. Brown in detail and found that it was the same species. J. Ostrom published his discovery in 1969, giving all referred remains the name Deinonychus antirrhopus. The generic name means in Greek, δεινός, 'terrible' and ὄνυξ, with the genitive ὄνυχος 'claw'. The specific name "antirrhopus", from the Greek ἀντίρροπος means "counterweight" and refers to the likely effects of a stiff tail. In July 1969, Ostrom published an extensive monograph on Deinonychus.
Although thousands of bones were available before 1969, many of the important bones were missing or difficult to interpret. There were few postorbital elements of the skull, there was no femur, sacrum, wishbone, or sternum, vertebrae were missing, and Ostrom thought he had only a small fragment of the coracoid. J. Ostrom's skeletal reconstruction of Deinonychus included a very unusual pelvic bone, a flat, trapezoidal pubis, different from that of other theropods, but the same length as the ischium and located next to it.
Later Discoveries
In 1974 Ostrom published another monograph on the shoulder of Deinonychus, in which he corrected that the pubis he described was actually a coracoid, an element of the shoulder. In the same year, another Deinonychus specimen was excavated in Montana by a Harvard University expedition led by Farish Jenkins. This discovery added several new elements such as well-preserved femurs, pubis, a sacrum, and better iliums, as well as elements of the foot and metatarsal. Ostrom described this specimen and reviewed the skeletal restoration of Deinonychus. This time very long pubes were seen, and Ostrom began to suspect that they may even have been facing backwards a bit like in birds.
A skeleton of Deinonychus including the bones of the original and most complete specimen can be seen in the American Museum of Natural History, with another specimen in the Museum of Comparative Zoology at Harvard University. The specimens at the American Museum and at Harvard are from a different location than those at Yale. Even these two skeletal mounts are missing elements including the sterna, sternal ribs, wishbone, and gastralia.
Even after all of J. Ostrom's work, several small blocks of material embedded in the rock remained unprepared in the AMNH warehouse. These consisted mostly of bones and isolated bone fragments, embedded in the original matrix, or in the surrounding rock in which the specimens ended up initially buried. An examination of these unprepared blocks by Gerald Grellet-Tinner and Peter Makovicky in 2000 revealed an interesting, overlooked feature. Several long, thin bones identified in the blocks as ossified tendons, structures that helped stiffen the tail of Deinonychus.w, turned out to be actually gastralia, abdominal ribs. But most significantly a large number of previously unnoticed fossilized eggshells were discovered in the rock matrix that had surrounded the original Deinonychus specimen.
In a later, more detailed report on the eggshells, Grellet-Tinner and Makovicky concluded that the eggs almost certainly belonged to Deinonychus, representing the first dromaeosaurid egg to be identified. Elsewhere, the outer surface of an eggshell was found in close contact with gastralia which would suggest that this Deinonychus may have been incubating its eggs. This implies that Deinonychus underwent body heat transfer as a mechanism for egg incubation, and indicates endothermy similar to modern birds. Additional study by Gregory Erickson and colleagues finds that this individual was between 13 or 14 years to death and their growth had stopped. Unlike other theropods, in his study of specimens found associated with eggs or nests, it had finished growing at the time of death.
Implications
Ostrom's 1969 description of Deinonychus has been described as one of the most important developments in mid-20th century paleontology. The discovery of this clearly active and agile predator did much to to change the scientific and popular conception of dinosaurs and opened the door to speculation that dinosaurs may have been warm-blooded. This paradigm shift has been called the dinosaur renaissance. Several years later, Ostrom noted similarities between the forelegs of Deinonychus and those of birds, an observation that led him to revive the hypothesis that birds descended from dinosaurs. Forty years later, this idea is almost universally accepted.
The discovery of the first remains of many Deinonychus by paleontologists John Ostrom and Grant E. Meyer in 1964 in southern Montana led Ostrom to surmise that Deinonychus lived in herds, something unthinkable for the time, which judged dinosaurs as animals of limited intelligence that could only lead a solitary life. He also found the first evidence that Deinonychus preyed on Tenontosaurus ; something that, supposedly, they could not do alone.
Deinonychus was likely feathered like its close relative Velociraptor, proven in 2007 based on feather markings on its arms. Such markings show where the feathers are anchored in living birds. This recent discovery added weight to already strong theories that all dromaeosaurids were feathered.
Due to its extremely bird-like anatomy and close relationship to other dromaeosaurids, paleontologists surmise that Deinonychus was probably covered in feathers. Clear fossil evidence exists for bird-style feathers for several related dromaeosaurids, including Velociraptor and Microraptor, although there is no known direct evidence for Deinonychus. such as range of motion in the forelimbs, paleontologists such as Phil Senter assumed the probable presence of flight feathers, which occur in all known dromaeosaurs with skin impressions.
Classification
Deinonychus is one of the best known of the Dromaeosauridae, along with the smaller and relatively close Velociraptor, from the Campanian of Central Asia. The clade they form is called Velociraptorinae. The name Velociraptorinae was first coined by Rinchen Barsbold in 1983 and originally contained only Velociraptor. Phil Currie later included more dromaeosaurids. Late Cretaceous Tsaagan from Mongolia and North American Saurornitholestes, may also be among the close relatives, but the latter is poorly known and difficult to classify. Velociraptor and its relatives used their claws more than their skulls as hunting tools, compared to dromaeosaurids such as Dromaeosaurus with more massive skulls. Along with Troodontidae, the dromaeosaurids of the Deinonychosauria clade are sister taxa to birds. Phylogenetically, Deinonychosauria is the group of non-avian dinosaurs closest to birds. In a 2015 analysis by paleontologists Robert DePalma, David Burnham, Larry Martin, Peter Larson, and Robert Bakker, using updated data from the Teroxide Working Group, places Deinonychus as basal in Dromaeosaurinae.
Phylogeny
The cladogram shows the phylogenetic position of Deinonychus within the Eudromaeosauria according to the analysis of Evans and colleagues in 2013.
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Cladogram based on 2015 study.
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Paleobiology
Predatory behavior
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Deinonychus teeth found in association with fossils of the ornithopod dinosaur Tenontosaurus are very common in the Cloverly Formation. Two sites have been discovered that preserve fairly complete fossils of Deinonychus close to Tenontosaurus. The first, the Yale site in Cloverly, Montana, includes numerous teeth, four adult Deinonychus fossils and one juvenile. The association of this number of Deinonychus skeletons in a single location suggests that Deinonychus may have fed on, and perhaps hunted, that animal. Ostrom and Maxwell even used this information to speculate that Deinonychus may have lived and hunted in packs. The second site is in the Antlers Formation of Oklahoma. The site contains six partial skeletons of Tenontosaurus of various sizes, along with a partial skeleton and many teeth of Deinonychus. A humerus of Tenontosaurus even bears what may be Deinonychus tooth marks. D. Brinkman et al.. In 1998, they specified that Deinonychus had an adult weight of 70 to 100 kilograms, while adult Tenontosaurus weighed between 1 and 4 tons. A lone Deinonychus could not kill an adult Tenontosaurus, suggesting that hunting in packs would be possible.
A 2007 study by B. T. Roach and D. L. Brinkman have added to the question of cooperative behavior during Deinonychus pack hunting, based on what is known of modern carnivore hunting and the taphonomy of Tenontosaurus sites. Modern archosaurs, birds, crocodiles, and the Komodo dragon exhibit little or no form of cooperative hunting, instead they are generally solitary hunters, or group around the carcasses of previously killed animals, where much conflict occurs between individuals of different species. the same species. For example, in situations where groups of Komodo dragons are feeding together, the larger individuals eat first and will attack smaller Komodo dragons that attempt to feed. If the smaller animal is killed, it is cannibalized. When this information is applied to Tenontosaurus sites, it appears to be consistent with that found among Komodo dragons and crocodiles. The Deinonychus skeletal remains found at these sites are from subadults and the missing pieces are consistent with predation by other Deinonychus. Li et al. describe track sites with similar foot spacing and parallel tracks, implying gregarious herd behavior rather than uncoordinated feeding behavior.
In 2011, a study led by Denver Fowler suggested a new method of hunting Deinonychus and other dromaeosaurs to feed on small prey. This model proposes that Deinonychus is It pounced on its prey like modern accipitrids, dropping its weight on its prey and holding it in its claws. Like these birds, the dromaeosaur would begin to devour its still-living prey, while it died from hemorrhaging. This proposition is based on the comparison of the anatomy of dromaeosaurids with current predatory birds. The proportions of the legs and feet are similar to those of eagles and hawks, while the strong feet and short metatarsals of Deinonychus are reminiscent of those of owls. The proposed method of predation would be consistent with other aspects of Deinonychus anatomy, such as its unusual jaw and arm morphology. The arms were probably covered in long feathers, and may have been used as flapping stabilizers for balance while the top of a prey animal struggled, along with the stiff counterweight tail. Its jaws, which are thought to have had a comparatively weak bite force, could have been used for saw motion bites, like the modern Komodo dragon which also has a weak bite force, to finish off its prey, if his kicks weren't powerful enough.
Bite Force
In 2005, bite force estimates for Deinonychus were made for the first time, based on the reconstruction of the jaw musculature. This study concluded that Deinonychus was likely to have had a maximum bite force only 15% that of the modern American alligator. A 2010 study by Paul Gignac and colleagues attempted to estimate bite force directly based on newly discovered Deinonychus tooth puncture marks on the bones of a Tenontosaurus. These markings came from a large individual, and provided the first evidence that large Deinonychus could bite to the bone. As for the use of tooth marks, Gignac's team was able to determine that the bite force of Deinonychus was significantly greater than previous studies had estimated from biomechanical studies alone. They found that the bite force of Deinonychus reached between 4,100 and 8,200 newtons of force, greater than living carnivorous mammals such as hyenas, and equivalent to a crocodile of similar size.
However, Gignac and colleagues also noted that Deinonychus bone puncture marks are relatively rare, and unlike larger theropods with many known puncture marks, such as the Tyrannosaurus, Deinonychus probably did not frequently bite through bones or eat them. Instead, it is likely that they used their large bite force for defensive purposes or in capturing prey, rather than feeding.
Role of members
Despite being the most distinctive feature of Deinonychus, the shape and sickle curvature of the claw varies among specimens. The type specimen described by Ostrom in 1969 has a strongly sickle-curved claw, while a newer specimen described in 1976 had a claw with a much weaker curvature, more similar in profile to that of normal claws on the remaining toes of the claw. ft. Ostrom has suggested that this difference in the size and shape of the sickle claws might be due to individual, sexual, or age-related variation, but admitted that he could not be certain.
This is anatomical and digital evidence that this heel was raised off the ground, while the dinosaur walked on the third and fourth toes.
Ostrom suggested that Deinonychus could kick with its sickle claw to cut and tear its prey. Some researchers even suggested that the heel was used to disembowel large ceratopsian dinosaurs. Other studies have suggested that the sickle claws were not used to rip, but to deliver small stab wounds to their victim. In 2005, Manning and colleagues conducted tests on a robotic replica that exactly matches the anatomy of Deinonychus and Velociraptor, which uses hydraulic pistons to make the robot hit a pig carcass. In these tests, the claws make only superficial punctures and were unable to cut or trim. The authors suggested that the claws would have been more effective for climbing than for hitting a kill.
Ostrom compared Deinonychus to the ostrich and cassowary. He noted that bird species can cause serious injury with the large claw to the second toe. The cassowary has claws up to 125 millimeters long. Ostrom quoted Gilliard from 1958 when he said that what can break an arm or dismember a man. Kofron between 1999 and 2003 studied 241 documented cassowary attacks and found that they left one human and two dogs dead, but there is no evidence that cassowaries can dismember or dismember other animals. Cassowaries use their claws to defend themselves, attack and threaten animals, and in intraspecific display displays. The seriema also have an enlarged second foot-claw, and use it to tear small prey before swallowing. In 2011, a study suggested that the sickle claw was probably used to hold prey steady while biting, rather than as a cutting weapon.
Biomechanical studies by Ken Carpenter in 2002 confirmed that the most likely function of the arms was to grasp prey, as their great lengths would have allowed a longer reach than for most other theropods. The large, elongated coracoid suggests strong muscles in the arms, furthering this theory. Carpenter's biomechanical studies using bone casts also showed that Deinonychus could not bend. her arms against her body like a bird, contrary to what was deduced in 1985 from earlier descriptions by Jacques Gauthier and Gregory S. Paul in 1988.
Studies by Phil Senter in 2006 indicated that the arms of Deinonychus could be used not only to grasp but also to carry objects towards the chest. The probable presence of a large feathered wing in Deinonychus, however, would have limited the range of movement of the arms to some degree. For example, when Deinonychus brought its arms forward, the palm of the hand automatically turned to an upward position. This would have caused one wing to block the other if both arms were outstretched at the same time, leading Senter to conclude that pulling objects to the chest would have been accomplished with only one arm at a time. The function of the fingers would also have been limited by the feathers, for example, in activities such as digging into crevices for small prey only the third digit of the hand could have been used, and only perpendicular to the position of the wing. Alan Gishlick, in a 2001 study of the arm mechanics of Deinonychus, found that even if large wing feathers were present, the grasping ability of the hand would not have been significantly impeded. This would have been perpendicular to the wing, and would likely be held by both hands simultaneously in a 'bear hug', a fact supported by later studies of the arm by Carpenter and Senter. In a 2001 study by Bruce Rothschild and other paleontologists, 43 hand bones and 52 foot bones referring to Deinonychus were examined for signs of stress fracture, and none were found. The second phalanx of the second toe of the foot in specimen YPM 5205 shows a healed fracture.
Parsons and Parsons have shown that juvenile and young adult specimens of Deinonychus show some morphological differences from adults. For example, the arms of the juveniles were proportionally longer than those of the adults, a possible indication of a difference in behavior between the juveniles and the adults. Another example of this could be the function of the claws on the foot. Parsons and Parsons have suggested that the curvature of the claw, which Ostrom [1976] had already shown to be different between specimens, was perhaps greater for Deinonychus juveniles, as this might help to climb to trees, and that the claws became straighter as the animal increased in size and began to live exclusively on land. This was based on the hypothesis that some small dromaeosaurids used their foot claws for climbing. In a 2015 paper, reanalysis of immature fossils reported that the open and mobile nature of the shoulder joint might have meant that young Deinonychus were capable of some form of flight.
Speed
Dromeosaurids, especially Deinonychus, are often depicted as unusually fast animals in the mass media, and Ostrom himself speculated that Deinonychus was fast in its original description. However, when the first Deinonychus was described, it lacked a complete leg, and Ostrom speculated about the length of the femur, which was later found to be oversized. In a later study, Ostrom observed that the ratio of the femur to the tibia is not as important in determining speed as the relative length of the foot and lower leg. In modern birds, such as the ostrich, the ratio between the foot and the tibia is 0.95. In unusually fast dinosaurs like Struthiomimus, the ratio is 0.68, but in Deinonychus, the ratio is 0.48. Ostrom stated that "only one conclusion is reasonable, Deinonychus was not particularly fast compared to other dinosaurs, nor to modern ratites".
The low distal hindlimb ratio in Deinonychus is due in part to an unusually short metatarsal. The ratio is actually larger in smaller individuals than in larger ones. J. Ostrom suggested that the short metatarsus may be related to sickle claw function, and used the fact that it appears to get shorter as individuals age as support for this. He interpreted all these characteristics, the short second toe with the enlarged claw, the short metatarsal, etc. as an aid to the use of the hind leg as an offensive weapon, where the claw would swing down and back, and the leg would push down and back at the same time, tearing into the prey. Ostrom suggested that the short metatarsal reduced the overall stress on the leg bones during such an attack, and interpreted the unusual arrangement of muscle attachments on the Deinonychus leg as support for his idea that a system of distinct muscles were used in predatory movement and in walking. Therefore, Ostrom concluded that the legs of Deinonychus represented a balance between the current adaptations necessary for an agile predator, and the characteristics to compensate for being its sole weapon of the foot.
In his 1981 study of dinosaur tracks found in Canada, Richard Kool made crude estimates of walking speed based on various track tracks made by various species in the Gething Formation of British Columbia. R. Kool estimated for one of these trace ichnospecies, Irenichnites gracilis, which may in fact have been Deinonychus, a walking speed of 2.8 meters per second, about 10.1 kilometers per hour.
Eggs
The identification in 2000 of a probable Deinonychus egg associated with one of the original specimens allowed comparison with other theropod dinosaurs in terms of egg structure, nest, and reproduction. In their 2006 study of the specimen, Grellet-Tinner and Makovicky examined the possibility that dromaeosaurids had been feeding on the eggs, or that fragments had been associated with the Deinonychus skeleton by coincidence. They ruled out the idea that the egg had been a theropod meal, noting that the fragments were sandwiched between the gastralia and arm bones, making it impossible for them to represent the animal's stomach contents. In addition, the manner in which the egg had been crushed and fragmented indicated that it had been intact at the time of burial, and was broken by the fossilization process. The idea that the egg was randomly associated with the dinosaur was also found to be unlikely, as the bones surrounding the egg had not been scattered or disarticulated, but remained fairly intact relative to their positions in life, indicating that the area around the egg was not disturbed during preservation. The fact that these bones were gastralia, which are very rarely found articulated, supported this interpretation. All the evidence, according to Grellet-Tinner and Makovicky, indicates that the egg was intact under the body of Deinonychus when it was buried. It is possible that this represents brooding or nesting behavior in Deinonychus similar to that seen in troodontids and oviraptorids, or that the egg was in fact inside the oviduct when the animal died.
Examination of the microstructure of the Deinonychus egg confirms that it belonged to a theropod, since it shares characteristics with other known theropod eggs and shows differences with ornithischian and sauropod eggs. Compared to other maniraptor theropods, the Deinonychus egg is more similar to oviraptorid than to troodontid, despite studies showing that the latter are as closely related to dromaeosaurids as Deinonychus. While the egg was too broken to accurately determine its size, Grellet-Tinner and Makovicky estimated a diameter of around 7 centimeters based on the width of the pelvic canal through which the egg must have passed. This size is similar to the 7.2 centimeter diameter of the largest egg of Citipati, an oviraptorid. Citipati and Deinonychus also shared the same total body size, supporting this estimate. Furthermore, the thickness of the eggshells of Citipati and Deinonychus are nearly identical, and since shell thickness correlates with egg volume, these data support the idea that the eggs of these two animals were nearly equal in size.
Paleoecology
Geological evidence suggests that Deinonychus inhabited floodplain or swampy areas. The paleoenvironment of both the Cloverly and Antlers formations, where remains of Deinonychus have been found to consist of forests, river deltas, and lakes, not unlike what is now Louisiana. Other animals that shared this world with Deinonychus to the armed herbivore Sauropelta, the largest of the raptors Utahraptor and the ornithopods Zephyrosaurus and Tenontosaurus. In Oklahoma, the Deinonychus ecosystem also included the theropod Acrocanthosaurus, the gigantic Sauroposeidon, the crocodilian Goniopholis, and fish Lepisosteiformes such as Lepisosteus. If the teeth found in Maryland are from Deinonychus, then its neighbors would include Astrodon, Dryptosaurus and a nodosaurid, called Priconodon known only by teeth. The middle portion of the Cloverly Formation ranges in age from 115 ± 10 million years near the bottom to 108.5 ± 0.2 million years near the top.
In popular culture
Deinonychus featured prominently in Michael Crichton's 1990 novel Jurassic Park and its 1993 film adaptation, directed by Steven Spielberg. However, Crichton and Spielberg chose to use the name Velociraptor for these dinosaurs, rather than Deinonychus. During the writing process, Crichton met with John Ostrom on several occasions to discuss the details of the possible range of behavior and live appearance of Deinonychus. At one point Crichton apologized by telling Ostrom that he had decided to use the name Velociraptor instead of Deinonychus for his book, because he felt the former name was too & # 34; more dramatic & # 34;. Despite this, according to Ostrom, Crichton stated that the Velociraptor in the novel was based on Deinonychus in almost every way, with only the name being changed. Jurassic Park filmmakers followed suit, designing the film's models based almost entirely on Deinonychus instead of the actual Velociraptor, and reportedly requested all of Ostrom's published work. on Deinonychus during production. As a result, these dinosaurs in the film were portrayed with the size, proportions, and snout shape of Deinonychus.
Deinonychus has appeared in The Land Before Time franchise in the 2000 film The Land Before Time VII: The Stone of Cold Fire, but only in one story during the film in which they attack a herd of herbivorous dinosaurs consisting of Parasaurolophus, 'Ouranosaurus, Styracosaurus, and 'Ankylosaurus. Deinonychus has also played a leading role in dinosaur documentaries such as Clash of the Dinosaurs and Jurassic Fight Club.
Old Lace, Gertrude Yorkes' partner in the Marvel comics and TV show Runaways was correctly identified by Victor Mancha as Deinonychus after the group assumed she was a Velociraptor.