Occurrence of the Ordovician-type aglaspididTremaglaspisin the Cambrian Weeks Formation (Utah, USA)

Abstract

AbstractThe Guzhangian Weeks Formation preserves a diverse, yet virtually unstudied, non-trilobite arthropod fauna. Here we describeTremaglaspis vanroyisp. nov., the oldest representative of an enigmatic group of extinct arthropods, the Aglaspidida.Tremaglaspiswas previously known from the Lower Ordovician and its morphology was regarded as particularly derived within the clade. Its occurrence in the Cambrian of Utah suggests that much of the early evolutionary history of the Aglaspidida remains unknown. A review of the environmental settings of previous aglaspidid findings suggests that these arthropods preferentially inhabited shallow-water environments, which may partially explain their limited fossil record.