known galeaspids, such as those of the genera Hanyangaspis and Dayongaspis, first appear near the start of the Telychian age, of the latter half of the Llandovery epoch of the Silurian, about 436 million years ago. During the transition from the Llandovery to the Wenlock, the Eugaleaspids underwent a diversification event. By the time the Wenlock epoch transitioned into the Ludlow Epoch, all of the eugaleaspids, save for the Eugaleaspidae, were extinct. The Eugaleaspidae lived from the Wenlock, and were fairly long-lived, especially the genus Eugaleaspis. The last of the Eugaleaspididae disappeared by the end of the Pragian Epoch of the Lower Devonian. The first genus of Geraspididae, the eponymous Geraspis, appears during the middle of the Telychian. The other genera of Polybranchiaspidida appear in the fossil record a little after the beginning of the Lochkovian Epoch, at the start of the Devonian. The vast majority of the supraorder's genera either date from the Pragian epoch, or have their ranges end there. By the time the Emsian epoch starts, only a few genera, such as Duyunolepis and Wumengshanaspis, survive, with most others already extinct. The last galeaspid is an as yet undescribed species and genus from the Fammenian epoch of the Late Devonian, found in association with the tetrapod Sinostega and the antiarch placoderm Remigolepis, in strata from the Northern Chinese province of Ningxia. Taxa Family Hanyangaspididae Pan & Liu 1975 Hanyangaspis Pan & Liu 1975 Nanjiangaspis Wang et al. 2002 Kalpinolepis Wang, Wang & Zhu 1996 Konoceras Pan 1992 Latirostraspis Wang, Xia & Chen 1980 Family Xiushuiaspididae Pan & Liu 1975 Changxingaspis Wan 1991 Microphymaspis Wang et al. 2002 Xiushuiaspis Pan & Wang 1983 Family Dayongaspididae Pan & Zen 1985 Dayongaspis Pan & Zen 1985 Platycarpaspis Wang et al. 2002 Order Eugaleaspidiformes Liu 1965 Yongdongaspis Chen et al., 2022 Family Shuyuidae Shan et al. 2020 Meishanaspis Wang 1991 Shuyu Gai et al. 2011 Family Tridenaspididae Liu 1986 Pterogonaspis Zhu 1992 Tridenaspis Liu 1986 Family Sinogaleaspididae Pan & Wang 1980 Anjiaspis Gai & Zhu 2005 Sinogaleaspis Pan & Wang 1980 Rumporostralis Shan et al. 2020 Family Eugaleaspididae Liu 1980 ?Liuaspis Whitley 1976 non Borchsenius 1960 Dunyu Zhu et al. 2012 Eugaleaspis Liu 1965 [Galeaspis Liu 1965 non Ivshin ex Borukaev 1955] Nochelaspis Zhu 1992 Pseudoduyunaspis Wang, Wang & Zhu 1996 Yunnanogaleaspis Pan & Wang 1980 Super order Polybranchiaspidida Liu 1965 Order Polybranchiaspidiformes Janvier 1996 Family Gumuaspididae Gai et al. 2018