Ankylosaurs

By | September 9, 2016

Also known as the “armored dinosaurs” or “tank dinosaurs,” the members of this family were built like tanks. Their squat bodies were covered with defensive armor plates and spikes formed from bony growths that developed in the skin. Without this protection, these plant-eaters would have been at the mercy of much swifter and sometimes bigger carnivores.

FAMILY FACT FILE

Key features
■ Heavily armored bodies
■ Walked on all fours
■ Horny beak with teeth usually on lower jaw
■ Some ankylosaurs had tail clubs and horns on the back of the head
■ Others (known as nodosaurs) had large shoulder spikes

When
Ankylosaurs lived during the Jurassic and Cretaceous Periods.

Edmontonia (ED-mon-TOE-nee-a)

edmontonia


When: 75–65 million years ago (Late Cretaceous)

Fossil location: N. America

Habitat: Woodlands

Length: 23 ft (7 m)

Diet: Low-growing plants

Edmontonia was twice the weight of a rhino and armed with huge spikes jutting out of its shoulders. Perhaps it drove off attackers by charging and lunging into them, using the spikes as spears. Some scientists think it used its lethal shoulder spikes to fight others of its own kind in battles over territory or mates.

Ankylosaurus (ANK-ill-oh-SORE-us)

ankylosaurus


When: 70–65 million years ago (Late Cretaceous)

Fossil location: N. America

Habitat: Woodlands

Length: 20 ft (6 m)

Diet: Low-growing plants

Ankylosaurus was the largest ankylosaur ever. Hundreds of armor plates studded its thick skin, and small armor plates even covered its eyelids. The armor formed from bony plates called osteoderms that grew within the skin, much like the armor plating of a crocodile’s skin. Ankylosaurus was also equipped with a huge tail club that it could swing at attackers with bone-shattering force.

Minmi (MIN-mee)

minmi


When: 120–115 million years ago (Early Cretaceous)

Fossil location: Australia

Habitat: Scrubby and wooded plains

Length: 10 ft (3 m)

Diet: Leaves, seeds, small fruit Minmi was one of the smallest of the ankylosaurs. Small, rounded armor plates covered its body, including its belly. Extra bones along its back may have supported its back muscles. Its beak was sharp, and it had small, leaf-shaped teeth with sawtooth edges. Fossilized food remains in the belly of Minmi reveal that it ate leaves, seeds, and small fruits.

Gastonia (gas-TOE-nee-ah)

gastonia


When: 125 million years ago (Early Cretaceous)

Fossil location: USA

Habitat: Woodlands

Length: 13 ft (4 m)

Diet: Plants

Only the bravest or most desperate predator would risk attacking Gastonia. A walking fortress, it was covered from head to tail with rows of huge, bladelike spikes of bone. It had no tail club, but its spiked tail could swing from side to side to inflict savage injuries. The bone forming the top of its skull was dome-shaped and extra thick—perhaps males had head-butting contests over territories or mates.

Gargoyleosaurus (GAR-goil-oh-SORE-us)

gargoyleosaurus


When: 155–145 million years ago (Late Jurassic)

Fossil location: USA

Habitat: Woodlands

Length: 13 ft (4 m)

Diet: Low-lying vegetation

Gargoyleosaurus had many unusual features for an ankylosaur. Unlike other members of the family, it had teeth at the front of the upper jaw, and its armor plates were hollow. It also had straight nostrils instead of the odd, looping ones seen in other ankylosaurs.

Sauropelta (SORE-oh-PELT-ah)

sauropelta


When: 120–110 million years ago (Early Cretaceous)

Fossil location: USA

Habitat: Woodlands

Length: 16 ft (5 m)

Diet: Plants

Predators risked deadly injury if they tried to bite this dinosaur’s neck, which bristled with vicious, hornlike spikes. A thick shield of armor plates covered its back and tail, giving Sauropelta its name (“shield lizard”). The shield was a jigsaw of small plates of bone that fitted together like tiles.

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