present in both genera, consisting of rounder plates that united on the midline of the animal, and one narrower element on each side with a sharp keel. In Panoplosaurus both the first and second bands of neck osteoderms had a third pair, lower on the side of the animal, again possessing a sharper keel than the elements on the top of the neck. While Edmontonia possesses lateral spines on the rear neck and shoulders, these are absent in Panoplosaurus. The arrangement of the armour on the torso and tail of Panoplosaurus is unknown, as no elements were found in articulation or association with this region of the skeleton. Classification Panoplosaurus was originally named simply as a genus of armoured dinosaur by Lambe in 1919, within the group Stegosauria, though it was subsequently specified by Sternberg in 1921 that within Stegosauria it was closest to taxa like Ankylosaurus and Euoplocephalus, and so within Ankylosauridae. The description of the new genus Edmontonia in 1928 by Sternberg identified it as a very close relative of Panoplosaurus, almost close enough to be considered the same genus, both being closely related to Palaeoscincus. Following further description of the armoured taxon Struthiosaurus by Franz Nopcsa in 1929, a different classification war proposed. Thyreophora replaced Stegosauria as the clade encompassing multiple families, with Panoplosaurus falling alongside Edmontonia, Dyoplosaurus, Hierosaurus, Scolosaurus and Stegopelta within the new subfamily Panoplosaurinae, which formed the family Nodosauridae with Nodosaurinae, Ankylosaurinae and Acanthopholinae. Nopcsa's classification of Panoplosaurinae was amended slightly by Charles W. Gilmore in 1930, who moved Palaeoscincus into the subfamily and removed Dyoplosaurus, which was discovered to have the skull of an ankylosaurine. Panoplosaurus was then placed in the new subfamily Edmontoniinae by Loris S. Russell in 1940, along with Edmontonia and Palaeoscincus, an equivalent classification to Gilmore's where Panoplosaurinae was used. Disagreeing with the classifications based on the work of Nopcsa, Evgeny Maleev moved Panoplosaurus into the family Ankylosauridae, which he considered to contain all ankylosaurs except Syrmosaurus. Coombs reviewed and revised the classifications of Ankylosauria in 1978, which he used as the group to encompass all heavily armoured ornithischians in a similar usage to Nodosauridae of Nopcsa. Within this suborder, he divided all taxa into two families, Ankylosauridae and Nodosauridae, distinguished by cranial and postcranial anatomy. Within Nodosauridae, which he considered a senior synonym of Acanthopholinae, Panoplosaurinae, Edmontoniinae, and other equivalent names, Coombs synonymized Panoplosaurus with Edmontonia, making Panoplosaurus