A new genus and species of agnathan Eugaleaspidiformes(Galeaspida), Yongdongaspis littoralis gen. et sp. nov., is described from the Llandovery(lower Silurian) Huixingshao Formation at Yongdong Town, Xiushan County, C...A new genus and species of agnathan Eugaleaspidiformes(Galeaspida), Yongdongaspis littoralis gen. et sp. nov., is described from the Llandovery(lower Silurian) Huixingshao Formation at Yongdong Town, Xiushan County, Chongqing, southwestern China. This new Telychian taxon morphologically exhibits some transitional states between Sinogaleaspidae and a cluster of higher eugaleaspidiforms containing Tridensaspidae, Eugaleaspidae, Yunnanogaleaspis, and Nochelaspis, which we term here as the ’eugaleaspid cluster’. Phylogenetic analysis of an extended character matrix of Galeaspida reveals Yongdongaspis, on which Yongdongaspidae fam. nov. is erected, as the sister taxon of this ’eugaleaspid cluster’, supported by two synapomorphies, the presence of one median transverse canal, and two lateral transverse canals leaving from the infraorbital canal. As the first fish described from the Llandovery Huixingshao Formation in Chongqing, Yongdongaspis provides new fossil evidence for the subdivision and correlation of the Upper Red Beds in South China.展开更多
基金supported by the Strategic Priority Research Program of Chinese Academy of Sciences(Grant Nos.XDA19050102 and XDB26000000)the National Natural Science Foundation of China(Grant No.41872023)+1 种基金the Key Research Program of Frontier Sciences,CAS(Grant No.QYZDJ-SSW-DQC002)the Mineral Resources Protection and Supervision Project:Evaluation and Survey of the Silurian Fish Fossil Resources of Youxiu Fold Belt,Chongqing。
文摘A new genus and species of agnathan Eugaleaspidiformes(Galeaspida), Yongdongaspis littoralis gen. et sp. nov., is described from the Llandovery(lower Silurian) Huixingshao Formation at Yongdong Town, Xiushan County, Chongqing, southwestern China. This new Telychian taxon morphologically exhibits some transitional states between Sinogaleaspidae and a cluster of higher eugaleaspidiforms containing Tridensaspidae, Eugaleaspidae, Yunnanogaleaspis, and Nochelaspis, which we term here as the ’eugaleaspid cluster’. Phylogenetic analysis of an extended character matrix of Galeaspida reveals Yongdongaspis, on which Yongdongaspidae fam. nov. is erected, as the sister taxon of this ’eugaleaspid cluster’, supported by two synapomorphies, the presence of one median transverse canal, and two lateral transverse canals leaving from the infraorbital canal. As the first fish described from the Llandovery Huixingshao Formation in Chongqing, Yongdongaspis provides new fossil evidence for the subdivision and correlation of the Upper Red Beds in South China.
