本文记述了盔甲鱼类的一新属种——珍奇秀甲鱼(Geraspis rara gen. et sp. nov.),它代表—新科(Geraspididae fam. nov)。头甲及其后覆盖鳞片部分呈正常连接。主要特征为:间带短,角呈狭长的三角形,伸向后方。侧背沟靠近头甲中背线。鳞...本文记述了盔甲鱼类的一新属种——珍奇秀甲鱼(Geraspis rara gen. et sp. nov.),它代表—新科(Geraspididae fam. nov)。头甲及其后覆盖鳞片部分呈正常连接。主要特征为:间带短,角呈狭长的三角形,伸向后方。侧背沟靠近头甲中背线。鳞为小而密集的菱形。展开更多
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
We present the first parsimony analysis of the agnathan subclass Galeaspida based on the analysis of 53 morph ological characters.Three most parsimonious cladograms(126 steps in length;CI=0.508;RI=0.801)were discovere...We present the first parsimony analysis of the agnathan subclass Galeaspida based on the analysis of 53 morph ological characters.Three most parsimonious cladograms(126 steps in length;CI=0.508;RI=0.801)were discovered.An amended classification of the Galeaspida is proposed corresponding to the present analysis.Our results suggest that hanyangaspids,xiushuiaspids and dayon-gaspids from the Llandovery-Wenlock of Silurian are basal galeaspids.Within the remaining galeaspids,three major mono phyletic groups(the Eugaleaspidiformes,the Polybranchiaspidiformes and the Huananaspidiformes)are well sup-ported.It is shown that the dorsal fenestrae of the headshield evolved twice within the Galeaspida,one in the polybranchi-aspidiform lineage,and the other in the huananaspidiform lineage(nested within the Huananaspidae).The chronological distribution of galeaspids highlights two radiations of the group,one for basal galeaspids and eugaleaspids in the Telychian(Llandovery)of Silurian,and the other for polybranchiaspidiforms and huananaspidiforms in the Lochkovian of Early Devonian.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.
基金This work was supported by grants from the National Natural Science Foundation of China(Grant No.40332017)the Special Funds for Major State Basic Research Projects of China(No.G2000077704)IGCP 491.We appreciate the review of manuscript by Chang Meemann and Zhang Jiangyong.
文摘We present the first parsimony analysis of the agnathan subclass Galeaspida based on the analysis of 53 morph ological characters.Three most parsimonious cladograms(126 steps in length;CI=0.508;RI=0.801)were discovered.An amended classification of the Galeaspida is proposed corresponding to the present analysis.Our results suggest that hanyangaspids,xiushuiaspids and dayon-gaspids from the Llandovery-Wenlock of Silurian are basal galeaspids.Within the remaining galeaspids,three major mono phyletic groups(the Eugaleaspidiformes,the Polybranchiaspidiformes and the Huananaspidiformes)are well sup-ported.It is shown that the dorsal fenestrae of the headshield evolved twice within the Galeaspida,one in the polybranchi-aspidiform lineage,and the other in the huananaspidiform lineage(nested within the Huananaspidae).The chronological distribution of galeaspids highlights two radiations of the group,one for basal galeaspids and eugaleaspids in the Telychian(Llandovery)of Silurian,and the other for polybranchiaspidiforms and huananaspidiforms in the Lochkovian of Early Devonian.
