Astraspida, or astraspids, are a small group of extinct armored jawless vertebrates, which lived in the Late Ordovician (about 450 million years ago) in...

(2025). The result of their maximum parsimony analysis is shown below: Astraspidida Thelodonti Galeaspida Osteostraci Lepidaspis Sansom, Robert S.; Randle...