Deinonychus

Deinonychus (say die-NON-ih-kus) was a raptor, a fast, clever, meat-eating dinosaur that walked on two legs. Its name means "terrible claw". That's because the second toe on each foot had a huge, curved claw shaped like a sickle, a hooked farm blade.

Fossil hunter Barnum Brown found the first bones in Montana in 1931, but he never gave the dinosaur a proper name. In 1964, scientist John Ostrom and his team dug up many more bones nearby, and Ostrom named Deinonychus in 1969.

Deinonychus had a long, stiff tail for balance, long arms with three clawed fingers, sharp, curved teeth, and a big brain for a dinosaur. It was a lot more like a bird than a lizard.

A grown-up Deinonychus was about 11 feet (3.4 metres) long from the tip of its nose to the end of its tail. That's about as long as a small car! Its hips were about 3 feet (0.9 m) off the ground, around the height of a kitchen table.

Scientists think it weighed about 150 to 220 pounds (70 to 100 kg), about the same as a grown-up person. Much of its length was its long, skinny tail, so it was lighter than it looks.

Deinonychus was a middle-sized raptor. It was much bigger than turkey-sized Velociraptor, but smaller than giant Utahraptor.

Almost certainly, yes! No feathers or skin have ever been found with a Deinonychus fossil. But its close cousins did have feathers. Microraptor fossils show feathers clearly, and a Velociraptor arm bone has little bumps called quill knobs, where big wing feathers were attached.

Because the whole raptor family had feathers, scientists draw Deinonychus covered in feathers too, with wing-like feathers on its arms and a feathery fan on its tail. It couldn't fly, though. A grown-up was far too heavy.

Deinonychus was a carnivore, so it ate meat. It had rows of sharp, curved teeth with jagged edges, like little steak knives.

Its teeth are often found next to the bones of Tenontosaurus (say teh-NON-toe-SORE-us), a big plant eater with a very long tail. A grown-up Tenontosaurus weighed 1 to 4 tonnes, way too big for one Deinonychus to take down alone.

In Montana, scientists found four grown-up and one young Deinonychus together with a Tenontosaurus. That made John Ostrom wonder if they hunted in packs, like wolves. Other scientists aren't so sure. They think Deinonychus might have crowded around a meal and squabbled over it, more like Komodo dragons do. Scientists are still working on the answer!

Meet more meat-eating dinosaurs on our Types of Dinosaurs page.

Remember the tall, clever raptors in Jurassic Park? The movie called them Velociraptors, but they were really based on Deinonychus. Author Michael Crichton said his raptors matched Deinonychus in almost every detail. He just thought the name "Velociraptor" sounded more dramatic.

Real Velociraptors were only about the size of a turkey. The movie raptors were even a bit bigger than Deinonychus, closer in size to Utahraptor. And unlike the movie ones, real raptors had feathers.

Weights are scientists' estimates.

Before Deinonychus, many people pictured dinosaurs as slow, cold-blooded, tail-dragging lizards. When John Ostrom studied Deinonychus, he saw an animal built to be active and agile, with a stiff tail held up off the ground and a body a lot like a bird's.

His work started what is called the "Dinosaur Renaissance", a big change in how scientists thought about dinosaurs. It also helped prove an amazing idea: birds are living dinosaurs!

• Raptor walk: walk around the room on tiptoe, keeping one finger on each hand pointed up like a raised sickle claw. Can you stay balanced? Try holding your arms out like feathered wings.
• Measure the claw: cut a strip of paper 5 inches (13 cm) long and curve it into a hook. Compare it with your hand.
• Blue egg hunt: paint some hard-boiled eggs blue-green and hide them for a Deinonychus nest hunt.
• Color a raptor: print a free page from our Dinosaur Coloring Pages and give it feathers. Nobody knows Deinonychus's real colors, so you can choose!