Nature, Published online: 21 May 2025; doi:10.1038/s41586-025-08944-wRe-examination of the presumed Cambrian fossil fish Anatolepis reveals previous misidentification of aglaspidid sensory structures as dentine, a vertebrate sensory tissue, showing it to be an arthropod, and shifting the origin of vertebrate hard tissues to the Middle Ordovician. #origin #vertebrate #teeth #evolution #sensory