Deinonychus is a dromaeosaurid dinosaur discovered in North America, with a body length reaching 3 to 4 meters. Although this figure is markedly smaller than that of other large theropod dinosaurs, it is significantly larger than that of other dromaeosaurids. The name “Deinonychus” is derived from the large, sickle-shaped claw on the second toe of the foot; later research has shown that this feature is widespread among dromaeosaurids and troodontids. The morphological description of Deinonychus was published in the late 1960s. Its discovery overturned prevailing notions about dinosaurs, demonstrating that they were not cold-blooded, lumbering “giant lizards”; rather, some were small and highly active.