Rammerheads are descended from a group of troodons that survived the extinction of most non-avian dinosaurs. They have filled the niche left behind by pachycephalosaurids (which didn't make it through the extinction). They are herbivores that feed on grass, leaves, berries, ivy (even posion ivys due to their strong immunity against the ivy's posion), ferns, cycads, and horsetails. There are more than 465 species of rammerheads, ranging from red fox-size to dryosaurus-size ones. They resemble a long-extinct psittacosaurus, but without quil-like feathers on its back, and it also has a bony head for head-butting against its rivals and/or would-be predators. They are actually tolerating human activities very well. They are native to North American forests, grasslands, savannas, scrublands, des