in front of the upper socket rim which is the more common position. Coombs explained this by assuming that these bones were located in the eyelid musculature and were probably mobile enough to be moved over the eyes. Defense The tail club of ankylosaurids has often been interpreted as a defensive weapon. In Euoplocephalus, the presence of ossified tendons only with the distal half of the tail may support such a function. Because only the distal half of the tail was stiffened by tendons, the anterior half could still move freely from side to side. The ossified tendons would have transmitted the force of the swing to the club and reinforced the supporting vertebrae. The club was likely held just above the ground, as there was not sufficient musculature to raise the tail very high. A 2009 study concluded that "large ankylosaurian clubs could generate sufficient force to break bone during impacts, while average and small ones could not". It has also concluded that "tail swinging behavior is feasible in ankylosaurids, but it remains unknown whether the tail was used for interspecific defense, intraspecific combat, or both". The tail club could be swung low, toward the fragile metatarsals or shin bones of attacking theropods. Senses and airflow Euoplocephalus had relatively small eyes, but this does not necessarily mean that it had restricted vision. The complex respiratory passages observed in the skull suggest that Euoplocephalus had a good sense of smell, although in 1978 an examination of casts of the endocranium did not show an enlarged olfactory region of the brain. Teresa Maryanska, who has worked extensively on Mongolian ankylosaurids, suggested that the respiratory passages were primarily used to perform a mammal-like treatment of inhaled air, based on the presence and arrangement of specialized bones, which are present in Euoplocephalus. A 2011 study found that the nasal passages of Euoplocephalus were looped and complex; possibly an adaptation for heat and water balance and vocal resonance, and researchers discovered an enlarged and vascularised chamber at the back of the nasal tract, which was considered by the authors to be an adaptation to improve its sense of smell. The researchers also managed to reconstruct the dinosaur's inner ear and concluded that it was capable of hearing at low frequencies. They suggested that this may have been an adaption to hearing low-toned resonant sounds produced by the nasal passages. Diet Euoplocephalus, like other ankylosaurians,