to an insect, the beetle Stereocephalus Lynch 1884 — so Lambe changed it to Euoplocephalus in 1910, with as combinatio nova (new combination name) Euoplocephalus tutus. The type species remains Stereocephalus tutus. In 1915, Edwin Hennig classified E. tutus under the genus Palaeoscincus Leidy 1856, coining a Palaeoscincus tutus. Today however, Palaeoscincus is considered to be a nomen dubium based on indeterminate ankylosaurian teeth. In 1964, Euoplocephalus was by Oskar Kuhn referred to Ankylosaurus, as a Ankylosaurus tutus. The genus name Euoplocephalus, meaning "well-armed head", is derived from the Greek words eu (εὖ) meaning "well", hoplo~ (ὁπλο~) meaning "armed", and kephale (κεφαλή) meaning "head". This name has been misspelled more than a dozen different ways in formal scientific literature. The specific name tutus means "safely protected" in Latin. The only valid species known today is Euoplocephalus tutus. Referred material During the early twentieth century many more ankylosaurid fossils were uncovered in North America. Some were referred to Euoplocephalus, others named as separate genera. In 1971 however, Walter Coombs submitted a dissertation containing a landmark re-appraisal of North American ankylosaurs. He noted that, among the many specimens similar to Euoplocephalus, their skulls varied so much that either every known specimen must be a new species, or they all represented individual variation within a single species: Euoplocephalus tutus. Starting from this assumption that there was only one species of ankylosaur during the Campanian stage of the Upper Cretaceous, Coombs synonymized the genera Anodontosaurus, Dyoplosaurus, and Scolosaurus with Euoplocephalus and the species A. lambei, D. acutosquameus, and S. cutleri with E. tutus, creating a species that spanned nearly ten million years, or the entire Campanian. The fossils now referred to this species contained more than forty individuals discovered in Alberta, Canada and Montana in the United States, which would have made Euoplocephalus the best known ankylosaurid. This included fifteen skulls, teeth, and a few almost-complete skeletons, found with the armor still attached. Individual armor plates are the most commonly found element from them. In 1978, Coombs even included the Asian ankylosaurid Tarchia in the genus, renaming it as Euoplocephalus giganteus. The synonymy of all Campanian North-American ankylosaurids was followed for several decades, until scientists from the University of Alberta began to re-examine the fossils. A 2009 study found that Dyoplosaurus is in fact a valid taxon, and identified unique characteristics that differentiated it from Euoplocephalus, including its triangular claws. Victoria Arbour (2010) argued