Euoplocephalus tutus YOO-oh-ploh-SEF-uh-lus

"Well-armored head"

Euoplocephalus silhouette
You 1.8 m (5.9 ft) tall
Euoplocephalus 6 m (19.7 ft) long
4 people holding hands
silhouette · Andrew Farke (CC-BY) via PhyloPic
Length
6 m (19.7 ft) — About 6 m long, ~2 tonnes — slightly smaller than Ankylosaurus.
Period
Late Cretaceous (77–75 Mya)
Place
North America · Alberta, Canada
Food
Herbivore — Tough low-growing plants, probably ground level only — the head was too low to reach high vegetation.
Clade
Ankylosauridae Dinosauria Ornithischia Thyreophora Ankylosauria

Euoplocephalus was an earlier and slightly smaller ankylosaur, living about ten million years before Ankylosaurus in roughly the same part of North America. It had the same plated armor and club tail, plus an unusual extra: bony eyelids that worked like blinds, snapping shut to protect the eyes.

What we know

  • More than 40 skeletons known, more than any other ankylosaur.
  • Bony eyelids — unique among armored dinosaurs.
  • Tail club similar to Ankylosaurus, ending in a fused mass of bone.
  • Lived in the Dinosaur Park Formation alongside Centrosaurus, Corythosaurus, and Gorgosaurus.

What we guess

  • Whether multiple ankylosaur species in the same area filled different ecological roles.
  • Whether the tail club was used in male-male combat or only against predators.
  • Why some ankylosaurs had clubs and others (nodosaurids) had spikes instead.