Deinonychus is an extinct genus of dromaeosaurid coelurosaurian dinosaurs that lived around 115 to 108 million years ago. The type species Deinonychus antirrhopus is one of the best-known dromaeosaurids till now.

Physical Description

Deinonychus had a 15 to 17 inches long skull that was fairly similar to that of an Allosaurus. It had powerful jaws with curved, serrated teeth. The skull and lower jaw possessed fenestrae. It is believed that they had a flexible neck. Their brain and eyes were relatively large. Deinonychus possessed sharp and curved claws on each forelimb; and four-toed hind foot with sickle-like claws. There is no evidence that they possessed any feathers.

Discovery

Deinonychus’ fossil remains have been recovered from the Cloverly Formation (dated early Cretaceous) in Montana and Wyoming, and the Antlers Formation in Oklahoma. The first fossil remains were unearthed in southern Montana in 1931 when paleontologist Barnum Brown was charged with excavating and preparing Tenontosaurus remains. In his field report, Brown revealed the discovery of a small carnivorous dinosaur. It was informally called ‘Daptosaurus agilis.’ In August 1964, Yale University’s Peabody Museum of Natural History team led by paleontologist John Ostrom found more skeletal material near Bridger. In the following two years, over one-thousand bones and remains of at least three individuals were found. The type specimen just had the complete left foot and partial right foot. Later, Ostrom and Grant E. Meyer studied their own material and Barnum Brown’s material and found that they belong to the same species. They formally named it Deinonychus antirrhopus. In 2000, Gerald Grellet-Tinner and Peter Makovicky described a lime-encased material that was sitting at the American Museum storage for a long time. They described previously identified ossified tendons as actually being the gastralia of the species. They also found previously unnoticed fossilized eggshells that had encircled the actual Deinonychus specimen. The outer surface of one eggshell was in close proximity of the gastralia triggering the hypothesis that they brooded on eggs and it led to the suggestion of their endothermy was like modern birds.

Etymology

The name Daptosaurus comes from Greek words “deinos” meaning ‘terrible’ and “onux, onukh” meaning ‘claw.’ The term “antirrhopus” (from the type species Deinonychus antirrhopus) is a Greek word meaning ‘counterbalancing.’ It refers to the assumed purpose of its stiffened tail.

Behavior and Adaptation

They shared their territory with Sauropelta, Zephyrosaurus, Tenontosaurus, Acrocanthosaurus, Sauroposeidon, Goniopholis and Deinonychus among others. Scientists believe that they lived and hunted in packs. They killed their prey like accipitrid birds of prey. They might have preyed upon Tenontosaurus as its remains have been found near the fossil remains of Deinonychus.

Their brain and body weight ratio suggested that that were one of the ‘intelligent’ dinosaurs. They were greatly specialized for swift movement and fierce attack. They used their claw to slash and cut its prey.

They are believed to be one of the fast running creatures of their time. Deinonychus, like other raptors, could run 40 at a speed of miles per hour on average. A study conducted in 2010 by Paul Gignac and his team suggested that they had a bite force somewhere between 4100 and 8200 newtons, which is greater than a modern-day hyena.