that of Carpenter from 2001 or David B. Norman in 2021 find Scelidosaurus and possibly other early forms like Emausaurus and Scutellosaurus to fall closer to Ankylosaurus than Stegosaurus, Carpenter and later Norman suggested redefining Ankylosauria to limit it to the two subclades Nodosauridae and Ankylosauridae, creating the new clade Ankylosauromorpha for all taxa closer to Ankylosaurus than Stegosaurus. However, as historically even these primitive forms were considered ankylosaurs if they were more derived than Stegosaurus, Madzia and colleagues considered a redefinition of Ankylosauria to be undesirable, instead preferring to abandon Ankylosauromorpha as a same-definition junior synonym of Ankylosauria. The informal clade Euankylosauria, suggested by Norman as an alternative to redefining Ankylosauria, was discussed as potentially being useful in future for the typical group of nodosaurids and ankylosaurids, and was defined in 2021 by Soto-Acuña and colleagues as such as the result of their novel phylogenetic results, which grouped Antarctopelta, Kunbarrasaurus (Minmi sp. of earlier analyses) and their new taxon Stegouros as a unique group of non-euankylosaurian ankylosaurs, which they gave the name Parankylosauria. The result of their phylogenetic analysis is below. Evolution The origin of ankylosaurs is poorly understood, and only a few specimens from the Middle Jurassic are known. The ancestry of ankylosaurs has long been sought among stegosaurs, the closest group to ankylosaurs compared to other dinosaurs. Currently, ankylosaurs are a close group of stegosaurs within the Eurypoda clade. They are united by the presence of osteoderms in the skin, the narrow triangular skull of stegosaurs is similar to that of nodosaurids, and some similarity is found in the structure of the palate. Since stegosaurs are known from the Middle Jurassic, ankylosaurs are probably of the same age. They may have split up during the Aalenian period, more than 170 million years ago, but they were definitely in Africa by the Bathonian due to the presence of Spicomellus in Morocco. There are no well-preserved remains of ankylosaurs of that age. An incomplete radius and ulna from the Isle of Skye in Scotland are known, the exact affiliation of which to ankylosaurs or stegosaurs is not established. Most likely, ankylosaurs followed a different evolutionary path than stegosaurs, although it is unknown when and how they split off. In the latter, the osteoderms become raised, and the lateral protection disappears. Ankylosaurs evolved towards the development of osteoderms on the surface of the skull, increased armor and further consolidation of