Euoplocephalus was an ankylosaur, an armoured dinosaur, that lived in North America during the Late Cretaceous Period. It may have wandered alone in search of plants and roots to eat. Euoplocephalus had a stocky, low-slung body with stout legs and clawed feet. Plates of bony armour, known as scutes, were embedded into skin on its head (including eyelids), neck, back and tail. The plates were dotted with thick studs. There were large spines on its shoulders and a heavy club of bone at the end of its tail. It had small teeth.

Ankylosaurs

Euoplocephalus means “well-armoured head”—for obvious reasons. The name Ankylosaurus means “stiffened reptile”, a reference to the way its bones were fused together. Saichania, an ankylosaur from East Asia, is Mongolian for “beautiful one”, not because of its rugged good looks, but because its fossilized bones were extremely well-preserved when discovered. Talarurus also lived in Mongolia in the Late Cretaceous. Its name means “basket tail”, after the shape of its tail club.

Tail club defence

Anklyosaurs like Euoplocephalus, Anklyosaurus and Talarurus all had a deadly weapon to defend themselves with. At the end of their tails was a "club", a large ball of bone. It could be swung from side to side into the body or head of any flesh-eater, such as a Tarbosaurus, that attacked them. The tail bones interlocked to form a stiff rod, increasing the swing force.

Spicomellus

The oldest anklyosaur known lived in North Africa 165 million years ago during the mid-Jurassic. Named Spicomellus, it is described in a 2025 study as "one of the strangest dinosaurs ever discovered." It was almost entirely covered by bony spikes. Those around its neck were more than a metre long, while others were fused to its ribs—a feature never seen in any other animal, living or extinct. Spikes also stuck out of its sides and hips, and ran the length of its back to the tip of its tail.

Facts about Euoplocephalus

Pronunciation: You-op-loh-SEFF-ah-lus

Size: 6 m (20 ft) long and 2.2 m (7.2 ft) tall

Where and when: Open woodland in North America, 85–66 million years ago (Late Cretaceous)

Diet: Low-growing plants and roots

Predators: Giant theropods such as Albertosaurus, Daspletosaurus and Tyrannosaurus rex

Features: Protective armour, spikes and tail club; huge stomach, capable of breaking down tough plant material; large nasal passages giving good sense of smell

Relatives: Ankylosaurus, (North America); Pinacosaurus, Saichania and Talarurus (East Asia), Spicomellus (North Africa)