Deinonychus

Deinonychus was a small meat-eating dinosaur. It lived in what is now North America during the Early Cretaceous Period.

This dinosaur had a large, sickle-shaped talon on the second toe of each foot. When not in use the claw was held off the ground to keep it sharp.

The species name - antirrhopus - means 'counterbalancing'. This is because Deinonychus' tail was long and stiff, helping to balance the animal's weight.

When we talk about raptors, we are really talking about dromaeosaurs. 'Raptor' isn't a proper scientific term. Dromaeosaurs were all small- to medium-sized hunters with large toe claws.

Some dromaeosaurs have the word 'raptor' in their names, such as Velociraptor, Bambiraptor and Utahraptor. But there are many others that don't, including Deinonychus and Achillobator. That's why it's misleading to call them all raptors.

Deinonychus was a close relative of Velociraptor. When the latter featured in the novel Jurassic Park, the author based the dinosaur's details on the bigger Deinonychus. The film and sequels did the same.

Nobody has found evidence to prove that Deinonychus had feathers. But scientists think it's very likely that it did.

Some very closely related dinosaurs - including Velociraptor - definitely had them.

The first Deinonychus fossils were found in southern Montana by John Ostrom and Grant Meyer in 1964. Ostrom published the findings and named the dinosaur five years later.

His work caused a widespread change of opinion among palaeontologists. Before, people tended to think of dinosaurs as being slow, lumbering, cold-blooded beasts. Ostrom's studies helped scientists realise that they could be athletic, warm-blooded animals.

This change of thought is sometimes called 'the dinosaur renaissance'. It brought a lot of new interest to the world of dinosaur science.

Although Deinonychus is often portrayed as a fast-moving hunter, it may not have been as agile as we first imagined.

Many researchers now think that Deinonychus wasn't especially quick on its feet compared to other dinosaurs, although it wouldn't have been slow as such.

Deinonychus had relatively short lower leg bones. Some experts think that these may have evolved to help Deinonychus attack with its toe claws. They suggest that the shorter bones helped to absorb the impact of its slashing strikes.

Other scientists aren't convinced that Deinonychus' toe claws were very effective as slashing weapons. They think the claws helped Deinonychus to climb or to pin smaller prey animals to the ground.

Tenontosaurus and Zephyrosaurus may have been among the dinosaurs hunted by Deinonychus.