Ther term ornithischia means “bird hipped” in Greek. Even though birds are technically theropods, this clade of dinosaurs had hips similar to today’s birds. Ornithischians also had a special bone called a predentary that allowed them to easily clip plant materials. Some experts also believe that a beak may have been attached here.
Ornithischians also had other features that group them together, like cheek teeth shaped like leaves, teeth that came together for grinding plants, tendons near the pelvis that hardened into bone, and five or more vertebrae attached to their pelvis.