Dromaeosaurs

By | September 9, 2016

The dromaeosaurs were small but ferocious hunters with bladelike teeth and vicious, hooked claws on their hands and feet. They were closely related to birds and may have evolved from a flying ancestor. Their long arms folded up like wings, and their bodies were fully feathered. Dromaeosaurs are sometimes also called “raptors,” a word that means “thief” or “grabber.”

FAMILY FACT FILE

Key features
■ Long, birdlike feathers on the arms, legs, and tail; downy feathers on body
■ Sickle-shaped claw on second toe
■ Long arms that fold against the body like wings

When
Dromaeosaurs appeared in the Jurassic, 167 million years ago, and died out at the end of the Cretaceous, 65 million years ago.

Dromaeosaurus (DROM-ee-oh-SORE-us)

dromaeosaurus-1


When: 75 million years ago (Late Cretaceous)

Fossil location: Canada

Habitat: Forests, plains

Length: 6.1/2 ft (2 m)

Diet: Flesh

About the size of Velociraptor, Dromaeosaurus had a stockier skull and a deeper lower jaw, suggesting it had a more powerful bite. It had large eyes and hunted by vision, perhaps stalking prey quietly like a cat does before leaping for the kill. Only a partial skull and a few bones of Dromaeosaurus have been found. The skeleton shown below is based on these and other closely related dromaeosaurs.

Utahraptor (YOU-tah-RAP-tor)

utahraptor


When: 130–120 million years ago (Early Cretaceous)

Fossil location: USA

Habitat: Plains

Length: 23 ft (7 m)

Diet: Flesh

Utahraptor was the largest dromaeosaur and reached about half a ton in weight, making it heavier than a grizzly bear. Like other dromaeosaurs, it had a large, hooked claw on its second toe that it might have used for slashing or stabbing a victim after leaping on it. One fossilized claw measures 9 in (24 cm) in length.

Deinonychus (dye-NON-ee-cuss)

Deinonychus-skeleton

Deinonychus skeleton


When: 115–108 million years ago (Early Cretaceous)

Fossil location: USA

Habitat: Subtropical swamps and forests

Length: 10 ft (3 m)

Diet: Flesh

Leopard-sized Deinonychus (“terrible claw”) is famous for its large toe claws. As in other dromaeosaurs, the claws flipped up off the ground when it was walking in order to stay sharp. Some experts think Deinonychus used its toe claws to slash the throat or belly of prey while kicking violently. Others think the claws were climbing aids in juveniles or used for clinging to prey. A stiff tail provided balance when leaping or climbing.

Velociraptor (vel-OSS-ee-rap-tor)

velociraptor


When: 85 million years ago (Late Cretaceous)

Fossil location: Mongolia

Habitat: Scrubland and deserts

Length: 6. ft (2 m)

Diet: Lizards, mammals, small dinosaurs

velociraptor-protoceratops-fossil

The fossil was founded in 1971 by a team of scientists in the Gobi Desert, Mongolia

Velociraptor played a starring role in Jurassic Park, where it was shown as twice its actual size. In reality it was a slender, feathered animal about the size of a wolf. The most spectacular fossil of Velociraptor is a complete skeleton locked in combat with a Protoceratops. They died in midfight, perhaps buried by a sudden sandstorm.
Like other dromaeosaurs, Velociraptor had huge, flickable toe claws and long, clawed arms that unfolded like wings to grapple prey. Although no feathered fossils of Velociraptor have been found, its arm bones have “quill nodes”—small bumps to which long feathers were anchored.

Bambiraptor (BAM-bee-rap-tor)

bambiraptor


When: 75 million years ago (Late Cretaceous)

Fossil location: N. America

Habitat: Woodland

Length: 2 ft (6 m)

Diet: Flesh

In 1995, 14-year-old Wes Linster was hunting for fossils with his parents in the mountains of Glacier National Park in Montana. He was thrilled to find parts of a skeleton. Later excavation revealed that Wes had found a tiny but perfectly preserved dromaeosaur.
Because of its size, scientists named it after the Disney character Bambi the deer. Bambiraptor was birdlike and probably feathered, with long hindlimbs that suggest it was a fast runner. It probably hunted small mammals and reptiles, snatching them in its clawed hands as a cat catches a mouse.
It had a very large brain relative to its body size, suggesting it was a quick-witted animal (or an infant). Some scientists think its small size allowed it to climb trees.

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