Deinonychus

Deinonychus was a medium-sized dromaeosaurid dinosaur that roamed floodplains and forests of North America during the Early Cretaceous period. Measuring roughly three metres long, it was about the weight of a large dog or human adult. Its discovery and subsequent restudy by John Ostrom in the late 1960s fundamentally transformed palaeontology, providing compelling anatomical links between non-avian theropods and birds. Deinonychus possessed large, grasping hands with three clawed fingers, a stiffened tail that acted as a dynamic counterbalance, and a formidable hyper-extendable sickle claw on each foot. These foot claws were likely used to grasp and pin down struggling prey like the ornithopod Tenontosaurus while the predator dispatched it. Its athletic build, large braincase, and close kinship with feathered paravians indicate an active, endothermic lifestyle.

John Ostrom's detailed description of this animal ignited the modern Dinosaur Renaissance by proving dinosaurs were active, bird-like creatures.

Where and when

Deinonychus lived in the Early Cretaceous, from 115 to 108 million years ago (Aptian-Albian age). Its remains come from United States, in the Cloverly Formation.

The numbers

Length 3.2 m (estimates run from 3 to 3.4 m). Mass about 77 kg. Hip height about 0.9 m. That is 1.9 human-lengths, or 0.29 of a double-decker bus. These are estimates from near-complete skeleton; fields marked estimated by the site are length, mass, hip height.

Compare Deinonychus with a bus Place on the timeline