The oldest eugaleaspiform fishes from the Silurian red beds in Jiangxi, South China and their stratigraphic significance

Abstract

• Two new species, Qingshuiaspis junqingi and Anjiaspis ericius , are established. • The eugaleapiforms-polybranchiaspiforms split occurred as early as early Telychian. • The Tangchiawu Formation can be correlated with the Qingshui Formation. • Eugaleapiformes provided key evidence for the correlation of Silurian LRBs in China. • The age of Shuyu should be modified as early Telychian, about 438 million years ago. Two new species of Eugaleaspiformes, Qingshuiaspis junqingi gen. et sp. nov. and Anjiaspis ericius sp. nov., were described from the lower Telychian Qingshui Formation in Wuning, Jiangxi Province. Our phylogenetic analysis reveals that Qingshuiaspis clusters with Shuyu , Meishanaspis , and Jiangxialepis to form the clade Shuyuidae, which is the sister to all other Eugaleaspiformes. These represent the oldest and most primitive fossil occurrences of Eugaleaspiformes in the marine Lower Red Beds of Silurian in South China. The new fossil evidence indicates that the vertebrate assemblages consisting of Shuyu , Meishanaspis , and Anjiaspis from the Silurian marine red beds in northwestern Zhejiang are more comparable to that of the Qingshui Formation (Lower Red Beds) than that of the Xikeng Formation (Upper Red Beds) in Jiangxi Province. The fish-bearing marine red beds in northwestern Zhejiang probably belong to the Tangchiawu Formation rather than the Maoshan Formation, and its age should be modified as early Telychian, about 438 million years ago. The oldest eugaleaspiforms and polybranchiaspiforms from the marine Lower Red Beds of Silurian in South China demonstrate that the two major groups of galeaspids split no later than the early Telychian.