Edmontonia was one of the largest and most widely distributed nodosaurids. One excellent specimen has allowed a good understanding of its anatomy and appearance. Bands of armor plates covered the upper surface of the neck and shoulder region, and smaller plates covered the rest of the back and tail. Several long spikes projected from each shoulder. The first two spikes pointed diagonally forwards, and the two further back pointed sideways. Edmontonia is skull had a long, low snout and its eye sockets were placed far back.