Dinosaur Species Evolution
Dinosaur Species Evolution
Deinonychus is a spectacular, but fairly small dinosaur. It measured about three and a half feet tall, and about nine feet long. Its weight is estimated at 150 pounds. By hunting in groups, members of a Deinonychus pack could have brought down dinosaurs much larger than themselves. In fact, the bones of several individuals of Deinonychus have been found with the skeleton of a large plant eating dinosaur, called Tenontosaurus.
Deinonychus belongs to a family of dinosaurs called dromaeosaurs. 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. Dromaeosaurs probably had keen vision and their brains were relatively large for a dinosaur. The dromaeosaurs lived throughout the Cretaceous period, 140 to 65 million years ago.
Deinonychus was highly specialized for swift movement and savage attack. With its terrible claw flicked forward it slashed its prey with one foot while standing on the other. This kind of behavior required good coordination, excellent eyesight and a high level of energy. By hunting in packs they may have brought down prey much larger than itself.
Deinonychus is probably the best known of the dromeasaurids, with nine specimens having been discovered since the genus was established in 1962 by John Ostrum. An interesting feature about this dinosaur is that its teeth are more backward pointing than other, larger theropods, suggesting that they are designed for feeding and not for the of prey. This points to the effectiveness of its hand and foot claws as weapons. Its skeletal design, according to Ostrum, clearly points to a very active predatory lifestyle - a hunter with both speed and agility. Its hands were very large and had a great range of movement and flexibility. As the dinosaur grew, long tendons along its tail hardened into a bone-like material to stiffen it and make it a useful mechanism for maintaining balance and direction in quick turns. A few scientists have argued that Deinonychus is a North American species of Velociraptor and does not merit its own genus.
In his 1986 book The Dinosaur Heresies, Dr. Robert Bakker puts forth the view that Deinonychus has many features found in birds and might be considered either a bird-like...