Euoplocephulus



The skull of Euoplocephalus can be distinguished from other ankylosaurids by several anatomical details, including: the pattern of bony sculpturing in the region in front of the eyes; the form of the small bones over the eyes which may have served as bony eyelids; the shallowness of the nasal vestibule at the entrance of the nasal cavity; the medial curve of the tooth rows in the upper jaw; and the teeth, which are relatively small, lack cingulums, and have variable fluting. The skull resembles a truncated equilateral triangle when viewed from above, and is slightly wider than it is long.[3 ] As in most quadrupedal ornithischians, its neck is short, the scapula is massive and robust, and the forelimbs are shorter than the hindlimbs. The tail is long and ends in a bony club. The distal half of the tail has ossified tendons.

The vertebral column of Euoplocephalus is made up of seven cervical vertebrae, 13 dorsal vertebrae, three sacral vertebrae, and at least 21 caudal vertebrae; the total number of caudal vertebrae is uncertain because several are fused to form part of the tail club. This fusion is also seen in other ankylosaurids; it is possible that the extent of fusion is an age-related feature. Like other ankylosaurians, the last four dorsal vertebrae and the first caudal vertebra are fused to the sacrum, forming a reinforced synsacrum.

The head and body of Euoplocephalus were covered with bony armor, except for parts of the limbs and possibly the distal tail. Much of this armor was made up of small ossicles. Larger flat scutes, conical plates, and disc-shaped plates were arranged in transverse bands among this pavement of ossicles. Two bands protected the dorsal and lateral surfaces of the neck, four were present across the front part of the torso, three protected the pelvis, and four were present on the anterior half of the tail. The banded arrangement is thought to have permitted some freedom of movement. Types of large scutes varied by body region. For example, the neck armor included large, crested plates, the shoulder region included tall plates near the midline of the body, the armor over the sacral region included large disc-shaped scutes, and tall conical scutes were present in the final band of the tail. Little is known about the armor of the limbs. Large keeled plates were present on the upper arms. undefined In addition, Euoplocephalus had large horns growing from the back of its head.&nbsp