Edmontonia (also known as Female Ankylosaur) is a lone Edmontonia and presumably her mate was killed possibly by a Gorgosaurus. She is in March of the Dinosaurs. She was seen in the begininng of the film where Scar the young Edmontosaurus tries to get a piece of leaf from a tree that fell, but the Edmontonia catches it first. When winter is about to start, the Edmontonia is seen eating rotten wood from dead logs. The grubs where in the rotten wood to provide a little extra protein to keep the 3 ton herbivore on the move and Scar does the same as well.
When the Edmontosaurus herd and Pachyrhinosaurus herd leave to the warmer areas, the Edmontonia watches the herd leave and she knows she is to heavy to keep up the herd and might accidentally whack any herd members with her spikes. She goes back to feeding as the Male Gorgosaurus watches her, but he instead finds Patch the Troodon.
When it was winter, the Edmontonia finds a last leaf on a tree and she tries to get it as she gets on a rotten log. As she catches it, the rotten log crumbles as she rolls down the hill and she lays upside down as she is completely helpless. 3 days later in the morning, the Edmontonia realised she was laying upside down for that long. A pack of Troodon show up and they decide to make a meal out of her. All the noise wakes up the King of the Forest. The Gorgosaurus comes out of his cave and tries to drag the Edmontonia back to his cave to feed himself.
When he slowly drags her onto a small slope she whacks him in the face with her tail, causing him to stumble back and the sudden movement of her tail combined with the partial slope she was on allowed her to right herself. The Edmontonia then charged and puts a final crushing blow on the Male Gorgosaurus; causing the Gorgosaurus to back off and limp back to his cave where he will eventually die in, either by starvation or blood-loss as "the tables have turned" with Patch watching the dying Gorgosaurus as he enters the cave. In the end of the film, The Edmontonia is seen happily feeding on ferns as she watches the sun rising once again.
Edmontonia also appears in Walking with Dinosaurs: The 3D Movie.