but these were referred on the assumption that Edmontonia was a synonym of Panoplosaurus, which was considered unjustified by Kenneth Carpenter in a 1990 review on Late Cretaceous nodosaurids. The referral of ROM 1215 to Panoplosaurus was questioned by Coombs in 1990, and Roland A. Gangloff referred it and the Alaskan specimen DPMWA 90–25 to Edmontonia in 1995 based on the anatomy of the lack of diagnostic traits, but Victoria Arbour and colleagues retained ROM 1215 in Panoplosaurus in 2009, limiting the genus to it, the holotype CMN 2759, and specimen AMNH 3072, all from the upper Dinosaur Park Formation. Arbour and Philip J. Currie further restricted Panoplosaurus to just the holotype in 2016, as a result of uncertainties surrounding the referrals of various specimens between it, Edmontonia rugosidens and Edmontonia longiceps, all from the Dinosaur Park Formation and similar deposits. Description Panoplosaurus was a rather large animal at , a comparable size to other ankylosaurs from the same location, and heavier than or approximately equivalent to all predators it coexisted with. Panoplosaurus was about long, and was armoured like most ankylosaurs, but lacked prominent spikes anywhere on its body. The characteristics of its armour are one of the features that distinguishes Panoplosaurus from its relative and contemporary Edmontonia, along with a tapering snout, lumpy cranial armour, a swollen vomer bone in the palate, tall neural arches and neural spines in the vertebrae, a small and round coracoid fused to the scapula, and a hand that may have only had three digits. There is also a prominent armour plate covering the cheek in the type specimen of Panoplosaurus, which may be unique feature of the taxon, or individual, depending on what additional skulls are referred to P. mirus. Skull The skull of Panoplosaurus is broad and depressed, narrowing towards the end of the blunt snout to form a triangular shape. At a total length of in a straight line, the skull is curved in a way that across the the same length is . Behind the , the skull reaches its maximum width of , giving it a very short and broad appearance. As other nodosaurid specimens from the same location that may be referred to Panoplosaurus lack the distinctively short snout of the holotype, it may be that its unique appearance is due to it being a different age or sex than other individuals. The orbits of Panoplosaurus are