What is a relative of the Ankylosaurus that has survived?

euoplosaurus, crichtonosaurus, stegosaurus. Each one bigger than the last. Which scientist are now discovering that that the ankylosaurus is probably the juvenile version of the stegosaurus. If you look at the skeletons of those dinosaurs you can see how they absorb the small spike and develop the large bone structures on the back. There are birds that change in bone structure as well while aging.