in a gradual curve towards the skull-roof. Lizards had a very different, more "open", occiput. Crocodiles were more similar but still had a concave skull rear. Bunzel considered whether it might be a dinosaur but in 1871 little dinosaurian occiput material had been described and it seemed to him that their skulls in this respect were more lizard-like. The only group showing a comparable rounding and fusion of skull bones were the birds. Bunzel sent a drawing and description to Professor Thomas Huxley in London, at the time one of the few dinosaur experts. Huxley agreed that the braincase resembled that of a bird, commenting "This skull-fragment is more bird-like, than any thing [sic] I have yet seen". Knowing that Huxley had named a reptile order Ornithoscelida for forms sharing with birds certain traits in the pelvis and hindlimbs, Bunzel ended his description with the prediction that "with time, it might also be possible to create an order Ornithocephala ('Bird Heads')". Bunzel was correct in assuming an affinity with birds but this was because birds are themselves dinosaurs. In dinosaurs, the rear skull bones are generally strongly fused. Nodosaurids did convergently develop a rounded skull. As the massive quadrates were lacking, the skull fragment gave a false impression of being lightly built. Ankylosaur material at the time was typically referred to the Scelidosauridae but because this was the first ankylosaur braincase to be described, the connection was not obvious. The first to understand it represented an armoured dinosaur was Nopcsa who in 1902 placed it in the Acanthopholididae. He later corrected its name to Acanthopholidae. Walter Coombs in 1978 stated it was a nodosaurid. Cladistic analysis of Struthiosaurus indicates that the taxon is a member of the Nodosauridae and suggested it may be one of the most basal ankylosaurs in the clade Ankylosauria. An analysis by Ösi in 2005, describing the taxon Hungarosaurus, found that while being younger in age than other nodosaurids, Struthiosaurus was one of the more basal taxa, although many features could not be coded for it. The cladogram below shows the results of the 2018 phylogenetic analysis of Rivera-Sylva and colleagues, resolving Struthiosaurus species within the clade Struthiosaurini as labelled by Madzia et al., with relationships outside Struthiosaurini excluded for simplicity. Paleobiology Examinations of the brain of Struthiosaurus published in 2022 suggest it had very poor hearing and relied mostly on its armor for defense against