Period: Late Cretaceous
Order, Suborder, Family: Ornithischia, Thyreophora, Nodosauridae
Location: North America (Canada, United States)
Length: 22 feet (6.6 meters)
Edmontonia would not have made an easy meal for a hungry tyrannosaur. It had a heavily armored body and large, forward-pointing shoulder spines. We know what Edmontonia looked like because two specimens were found with their armor and spikes preserved in the position they had in life. The bodies of these specimens may have dried out because of a drought and then been quickly covered by sediment when the rainy season began. Evidence for these changes in the climate is found in the growth rings of fossil wood.
Edmontonia walked on four legs and was a plant-eater. It had a pear-shaped skull (when viewed from the top). The neck and part of the back were protected by large, flat, keeled (ridged) plates. Smaller keeled plates covered the back, hips, and tail. Spines and large spikes along its sides would have made the animal look short and wide when viewed from the front. This made it look more menacing to an enemy.
An Albertosaurus was not the only animal it needed to protect itself from. A male Edmontonia probably fought with other males for territory and females. The larger males may have used their large shoulder spines for shoving contests. The spines of Edmontonia would have been dangerous to rival males or to an Albertosaurus or Daspletosaurus, if they got too close.