John Ostrom, reviewing this material decades later, realized that the teeth came from Deinonychus, but the skeleton came from a completely different animal. The team leader, paleontologist Barnum Brown, was primarily concerned with excavating and preparing the remains of the ornithopod dinosaur Tenontosaurus, but in his field report from the dig site to the American Museum of Natural History, he reported the discovery of a small carnivorous dinosaur close to a Tenontosaurus skeleton, "but encased in lime difficult to prepare."He informally called the animal " Daptosaurus agilis" and made preparations for describing it and having the skeleton, specimen AMNH 3015, put on display, but never finished this work.Brown brought back from the Cloverly Formation the skeleton of a smaller theropod with seemingly oversized teeth that he informally named "Megadontosaurus". The first remains were uncovered in 1931 in southern Montana near the town of Billings. Model in the "Feathered Dinosaurs and the Origin of Flight" traveling exhibit Additionally, teeth found in the Arundel Clay Facies (mid-Aptian), of the Potomac Formation on the Atlantic Coastal Plain of Maryland may be assigned to the genus. The Cloverly formation has been dated to the late Aptian through early Albian stages of the early Cretaceous, about 115 to 108 Ma. This kind of behavior required good coordination, excellent eyesight and a high level of energy.īased on the few fully mature specimens, Deinonychus could reach 3.4 meters (11 feet and 2 inches) in length, with a skull length of 410 mm (16.1), a hip height of 0.87 meters (2 feet and 10 inches) and a weight of 73 kilograms (161 lbs), though there is a higher estimate of 100 kilograms (220 lbs).įossilized remains of Deinonychus have been recovered from the Cloverly Formation of Montana and Wyoming and in the roughly contemporary Antlers Formation of Oklahoma, in North America. With its terrible claw flicked forward it slashed its prey with one foot while standing on the other. The dromaeosaurs lived throughout the Cretaceous period, 115 to 108 million years ago.ĭeinonychus was highly specialized for swift movement and savage attack. Dromaeosaurs probably had keen vision and their brains were relatively large for a dinosaur. They all share the same characteristics a lightly built skull with sharp backwardly curved teeth, elongated arms and hands with sharp claws, and an extraordinary sickle-like second toe claw which was carried raised off the ground to protect the sharp point. Despite the study, many paleontologists still believe that Deinonychus still hunts in packs.ĭeinonychus belongs to a family of dinosaurs called dromaeosaurs.
At any rate, modern pack hunting animals can't bring down prey that is too large, and Tenontosaurus was roughly as big as a rhinoceros, compared to the dog-sized Deinonychus. In addition recent studies have been bolstered their solitary lifestyle. This has been historically interpreted as evidence of pack hunting, though most experts nowadays think it was a scavenger congregation.
Bones of several individuals of Deinonychus have been found with the skeleton of a large plant eating dinosaur, called Tenontosaurus. It measured about 2.9 feet high at the hip, and about 11 feet long. An artist's illustration of Deinonychus antirrhopusĭeinonychus (meaning "terrible claw") is a dromaesaurid theropod dinosaur.