Stegosaurians, such as Stegosaurus, were characterized by narrow, pointed heads and distinctive back plates covered in horn-like sheaths. These herbivorous dinosaurs also featured tail spikes. The other options represent different dinosaur groups: Brachiosaurids were long-necked sauropods, Ankylosaurians had armored backs with bony plates, and Hadrosaurids were duck-billed dinosaurs.