Wikipedia:Today's featured article/May 29, 2011

A Deinonychus antirrhopus skeleton, in the Philadelphia Academy of Natural Sciences

Deinonychus is a genus of carnivorous dromaeosaurid dinosaur that existed during the Early Cretaceous. It contains only a single species, D. antirrhopus. Fossils of the 3.4 meter (11 ft) long dinosaur have been recovered from the U.S. states of Montana, Wyoming, and Oklahoma, though teeth attributed to Deinonychus have been found as far east as Maryland. A 1960s study of Deinonychus revolutionized the way scientists thought about dinosaurs, leading to the "Dinosaur renaissance" and igniting a debate on whether dinosaurs were warm-blooded. Where the popular conception of dinosaurs had been one of plodding reptilian giants, the study's description of Deinonychus' small body, sleek horizontal posture, ratite-like spine and enlarged raptorial claws suggested an active, agile predator. As in other dromaeosaurids, the tail vertebrae have a series of ossified tendons and super-elongated bone processes. These features would seem to make the tail into a stiff counterbalance, but fossils of closely-related species suggest that, in life, the tail could swish to the sides with a high degree of flexibility. Deinonychus teeth and other remains have been found closely associated with those of the ornithopod Tenontosaurus, implying that it was hunted or at least scavenged upon by Deinonychus. (more...)

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