Euoplocephalus - Meaning:well-armoured head 

Euoplocephalus (you-OH-plo-kef-ah-luss) meaning 'well-armored head' was one of the largest of the ankylosaurian dinosaurs, at about the size of a small elephant. It is also the ankylosaurian with the best fossil record, so its stiff shell of spiked armor, low-slung body, and great club-like tail are well documented.

It was active during the Late Cretaceous period.

Among the ankylosaurids, Euoplocephalus was exceeded in size only by Tarchia and Ankylosaurus. Euoplocephalus was 6 metres (20 ft) long and weighed about 2.2 tons. While it was 2.4 metres (8 feet) wide, it was low-slung, with short, stout legs. The rear legs were larger than the front legs and all four limbs were tipped with hoof-like claws. A trackway of an ankylosaur, found in 1996, at Sucre, Bolivia, indicates that Euoplocephalus could probably have moved with moderate speed.

Like all ankylosaurids, it had a flat, thick, triangular skull, with little capacity for a brain. The mouth was a horny beak and the teeth were small, weak and peg-like. It had a short neck.

The entire head and body of the Euoplocephalus are covered with bands of armor, which allowed a surprisingly amount of flexibility. It was the first ankylosaurid discovered with armored shutters that it could slide down to cover its eyelids.

Each narrow band of armor was composed of a thick oval plate, embedded in the thick surrounding skin, which was studded with short, horny spikes (dermal scutes, like those of crocodiles), which were about 10 to 15 centimetres (4 to 6 inches) long. In addition to the spines running down its back, Euoplocephalus had large horns growing from the back of its head.

It also had a bony club at the end of its rigid tail, which it carried in a raised position. The tail was muscular, so the club could be swung from side to side for defense.

Internally, many bones were fused together to provide support for the heavy armor. The backbone (the dorsal vertebrae) is merged with the ribs, and several of the backbones in front of the hips (presacral vertebrae) were also fused together into a rod. The tail is made from hardened tissues, which are fused to the tail bones (known as caudal vertebrae).

Euoplocephalus was a herbivorous dinosaur.