ankylosaurs

Ankylosaurs are a group of armored, herbivorous dinosaurs within the clade Ankylosauria. They are known for extensive dermal armor composed of osteoderms that covered the back, sides, and often the head. Fossils indicate ankylosaurs lived during the Early to Late Cretaceous, roughly from 125 to 66 million years ago, with remains found in North America, Europe, and Asia.

Anatomy and armor around the body were highly specialized. They were quadrupedal, with broad, low-slung bodies protected by a mosaic of bony plates and spines embedded in the skin. The skulls were broad and powerful, equipped with beaks and dental batteries for processing vegetation. A key distinction within Ankylosauria is between ankylosaurids and nodosaurids. Ankylosaurids typically possessed a tail club formed by fused vertebrae and large terminal osteoderms, while nodosaurids lacked the tail club and often bore spikes or elongated shoulder blades for defense.

Taxonomy centers on two primary families. Ankylosauridae includes genera such as Ankylosaurus, which is famous for its prominent tail club and armor. Nodosauridae comprises genera like Edmontonia, Panoplosaurus, and Pinacosaurus, which generally lack tail clubs but feature robust spikes and other armor arrangements. Despite differences, both families shared a common strategy of heavy armor as a primary defense against predators.

Ecology and life history are inferred from their anatomy. Ankylosaurs were likely low-nlung, slow-moving browsers that fed on low-lying vegetation. The armor and, in some species, tail clubs would have provided protection against theropod dinosaurs. Their relatively widespread geographic distribution and long paleoecological presence reflect a successful, if conservative, evolutionary path within herbivorous dinosaurs.