DEINONYCHUS ANTIRRHOPUS
DEINONYCHUS ANTIRRHOPUS
DEINONYCHUS ANTIRRHOPUS
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DEINONYCHUS ANTIRRHOPUS
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DEINONYCHUS ANTIRRHOPUS

MONTANA, USA

Details
DEINONYCHUS ANTIRRHOPUS
MONTANA, USA
From the Cloverly Formation, Wolf Canyon, Carbon County, Montana, the Early Cretaceous (circa 115-108 million years ago). The specimen of Deinonychus antirrhopus in remarkable state of preservation; approximately 126 fossil bones with remaining cast elements on custom frame
119 2⁄3 x 62 1⁄4 x 26in. (304 x 158 x 66cm.)
Provenance
Excavated at Wolf Canyon, Carbon County, Montana (in the W1/2NE1/4 of Section 23, Township 4 South, Range 24 East, P.M.M.) 2013-4
Pangea Fossils February 2015
Acquired from the above by the current owner
Literature
Bakker, R.T. The Dinosaur Heresies. (London, 1988)
Charig, A. A new look at the Dinosaurs. (London, 1979)
Ostrom, J.H. ‘Osteology of Deinonychus antirrhopus, an unusual theropod from the Lower Cretaceous of Montana’ in Peabody Museum of Natural History Bulletin. Vol. 30 (1969) pp. 1-165.
Grellet-Tinner, G. & Makovicky, P. ‘A possible egg of the dromaeosaur Deinonychus antirrhopus: phylogenetic and biological implications’ in Canadian Journal of Earth Sciences. Vol. 43 no. 6 (2006) pp. 705-719.
Exhibited
King of Dinosaurs, Natural History Museum of Denmark, Copenhagen, June 2020 to December 2021.

Brought to you by

James Hyslop
James Hyslop Head of Department, Scientific Instruments, Globes & Natural History

Lot Essay

1. Hector

Fifty million years before the reign of the dinosaurs ended in the age of Tyrannosaurus rex, a smaller, more agile, pack-hunting predator was the most feared animal of its time. The sleek, dynamic, and deadly Deinonychus is one of the most popular and well-known dinosaur species, but also one of the rarest fossils. Its popularity would peak following its leading appearance alongside T. rex as the Raptor in Jurassic Park. Taking his name from the greatest of the Trojan warriors, ‘Hector’ is the most complete skeleton of his species ever found. As the only Deinonychus in private hands, Hector is marking the debut of the iconic Raptor at auction.


2. Poised for Attack

Known for its long talon-like claws and elegant frame, Deinonychus flourished in western North America during the Early Cretaceous period. Part of the clade of dinosaurs called theropods (carnivorous animals that can walk on two legs), these sickle-clawed predators were armed with a deadly kick. Their fossil remains are typically found in the Cloverly Formation and the Antlers Formation, which are thought to have provided an environment of tropical and sub-tropical forests, lagoons, swamps, and river deltas for Deinonychus to inhabit.

The name Deinonychus was coined by palaeontologist, John Ostrom, in 1969 and translates to “terrible claw,” in reference to the killing claw on each foot. Shaped like a sickle and held up off the ground when not in use so as to maintain its lethal sharpness, this claw was used to disembowel its prey. It is believed that in order to use the claw with the highest degree of success, Deinonychus would have stood on one leg, holding the target with its long arms, and impaled its prey with a powerful kick. This attack was aided by the ability to use its arms, unlike many other dinosaurs, and the ability to stretch its hand to nine inches long. Indeed, it is believed that the main use of the arms was for this very purpose, and it is unlikely that the arms were ever used to walk on. Its deft movement and predatory skill were further supported by Deinonychus ability to stand on its hind legs when attacking other dinosaurs. This upright, offensive stance was facilitated by its long tail that provided essential balance thanks to rows of internal bundles of bony rods that gave the tail additional strength. The tail would otherwise be stretched horizontally when running, and contributed to the exceptional length of this animal, measuring approximately 3 meters long.

“Wickedly enlarged hind claw for disembowelling prey”– Robert Bakker, The Dinosaur Heresies (1986).

A highly sophisticated animal, Deinonychus was likely to have been a fast running and agile theropod as well as a dexterous killer. With a femur shorter than the lower leg bones, it shows adaptation for faster running. The large skull is broad but with fenestrae, reducing the weight of its head contributing to the ease of maneuverability and speed at which it could run. Furthermore, the enlarged optic lobes in the skull are suggestive of the exceptional eyesight that this dinosaur once possessed. Although the sickle claws on the hind legs were the main force of attack, Deinonychus may have had up to sixty or seventy fiercely sharp teeth producing a powerful and deadly bite. With remains of Tenontosaurus found with Deinonychus teeth, it is believed that they fed and possibly hunted in packs.

3. A Dinosaur Renaissance

Dinosaur remains have been found on every continent but Antarctica (due to the heavy ice acting as a barrier to excavations). The remains are only found in sedimentary rocks of the Late Triassic to the Late Cretaceous age, between 235 million and 65 million years old and usually occurring in freshwater or dry-land deposits.
The history of fossil hunting in America is rife with intrigue, drama, and competition. The late 1800s and early 1900s marked a first Golden Age of Dinosaur discoveries and was a period of intense and ruthlessly competitive fossil hunting known as the Bone Wars. Sparked by the great rivalry between Othniel Charles Marsh and Edward Drinker Cope, the two palaeontologists often employed underhanded methods, and even bribery, to outdo one another. By the end of the Bones Wars, both men had contributed significant paleontological findings, while also meeting their own social and financial ruin.

As the first raptor to be uncovered, the Deinonychus species represents one of the most important paleontological discoveries of the 20th century. Based on fossils found in 1964, Deinonychus was formally named by John Ostrom in 1969, who wrote extensively on the dinosaur, emphasizing the sophistication of the creature. Ostrom’s breakthrough study of Deinonychus in the late 1960s cemented the evolutionary link between dinosaurs and birds. He noted that the agility, high level of activity and sensitivity to stimuli of Deinonychus was closer to that of a bird rather than a reptile as most dinosaurs were categorized. The comparison with Archaeopteryx highlighted the classical view of birds as warm-blooded and dinosaurs as cold-blooded, proposing that Deinonychus was also warm-blooded. He argued that it shared the same characteristics as many flightless birds, noting long legs, long necks, horizontal bodies and potentially also feathers. This development was known as the Dinosaur Renaissance that led to a profound shift in thinking on nearly all aspects of dinosaur biology, including physiology, evolution, behavior, ecology, and extinction. Ostrom’s pioneering work on Deinonychus triggered a scientific revolution — boosting the development of ideas and knowledge surrounding dinosaurs, challenging the view that they were slow and lumbering but agile and intelligent creatures, while simultaneously igniting the much debated link with the origin of birds.

4. Superstar Species: The Celebrity of the Raptor

Deinonychus has featured prominently in popular culture, notably in both the 1990 and 1995 novels Jurassic Park, and The Lost World by Michael Crichton and their film adaptations directed by Steven Spielberg, albeit under the name Velociraptor. The Jurassic Park franchise boosted the Raptor’s reputation, although not creating a wholly accurate depiction of the Velociraptor. In reality, Velociraptor was the size of a turkey and its fossil remains are found exclusively in Mongolia, while in the films they were based on the larger, more aggressive predator: the Deinonychus from American sedimentary formations. The Jurassic Park films had followed suit of Michael Crichton’s novels, in which the author chose to use the name Velociraptor for added dramatics but based his animal entirely on the behaviours, size, and appearance of Deinonychus. Crichton, who consulted Ostrom for his books, was later apologetic about the name change.

Hector was excavated from Wolf Canyon, in Montana, and has since been in private hands, only being exhibited once before in Copenhagen at the Natural History Museum of Denmark. The exhibition “King of Dinosaurs” ran from June 19, 2020 to December 31, 2021 and showed Hector on display alongside five other dinosaurs, including the iconic Tyrannosaurus rex. Exhibiting these two ‘blockbuster’ species alongside one another, the Tyrannosaurs and Deinonychus display echoed the portrayal seen in Jurassic Park, further accentuating the celebrity status of Deinonychus.


5. Other specimens of Deinonychus

In comparison to the small handful of recorded specimens found over the decades, Hector is the single most complete specimen of Deinonychus ever found, and only the third complete skeleton.

The first fossilized remains of Deinonychus were recovered from the Cloverly Formation in Southern Montana near the town of Billings, by palaeontologist Barnum Brown, in 1931. Brown found a small carnivorous dinosaur skeleton similar to that of a Tenontosaurus, however, because it was encased in lime and therefore difficult to prepare, he never put it on display. It wasn’t until 1969 that John Ostrom and his assistant, Grant Meyer, re-examined it in detail and consequentially identified it as a Deinonychus. The estimated age of this fossilized skeleton is dated to the late Aptian to the early Albian stages of the Early Cretaceous. The skeleton that Meyer and Ostrom later identified is housed at the American Museum of Natural History in New York (specimen AMNH 3015) and is the second most complete Deinonychus skeleton, after Hector. Even after Ostrom’s work on this skeleton, there remained several blocks of lime-encased bones. In 2000, Gerald Grellet-Tinner and Peter Makovicky examined these blocks to find several long, thin bones that are the abdominal ribs as well as fossilized eggshells. This is the first dromaeosaurid egg to be identified and suggests that Deinonychus might have brooded its eggs for incubation, as modern birds do, further contributing to the link between dinosaurs and birds.

In August 1964, Ostrom and Meyer led an expedition from Yale’s Peabody Museum of Natural History to a newly discovered quarry in the Early Cretaceous Cloverly Formation of Southern Montana. Here they found a large, clawed hand, carnivore teeth and a foot with a sickle-shaped claw on the inner toe. Over the next two years they returned to this site and collected approximately one thousand bones, and although it is thought they were likely from only three or four dinosaurs, no complete single skeletons were found. They could only determine that two feet came from the same source – this would become the type specimen for the species, YPM 5205. The remaining bones were catalogued into fifty different entries at Yale’s Peabody Museum.

By 1969 numerous bones believed to have originated from Deinonychus had been excavated from different localities and essential missing bones including most of the postorbital skull elements, the femurs, sacrum, furcula, sternum and some vertebrae were identified. During a Harvard University expedition in Montana in 1974 led by Steven Orzack, many new bones were unearthed that would prove crucial to the understanding of the Deinonychus including femora, pubis, a sacrum, ilia, pes and metatarsus. These are now housed at the Museum of Comparative Zoology at Harvard University (specimen MCZ 4371).

Another revealing insight into Deinonychus behaviour has been suggested by the discovery of their teeth. Many Deinonychus teeth were found in the Cloverly Formation next to the remains of the ornithopod dinosaur Tenontosaurus. In the Yale quarry in the Cloverly of Montana, teeth belonging to four adult Deinonychus and one juvenile were discovered. With five sets of teeth found in the same quarry, it is probable that these dinosaurs all fed on the animal, and likely hunted bigger prey together. Teeth have also been found in the quarry of the Antlers Formation of Oklahoma, containing six partial skeletons of Tenontosaurus and many teeth of Deinonychus.

To this handful of recorded specimens found over the decades, with only two skeletons all in museum collections, Hector can now be added as the single most complete individual of Deinonychus ever found.

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