This study is based on both a generic and species level investigation of the individual size of the latest Permian conodont Neogondolella Pa elements collected from Meishan Section A, Changxing, Zhejiang Province. In ...This study is based on both a generic and species level investigation of the individual size of the latest Permian conodont Neogondolella Pa elements collected from Meishan Section A, Changxing, Zhejiang Province. In this study, an obvious size reduction of Neogondolella Pa elements within bed 24e of the upper Changxing Limestone is recognized. The size variation of the Neogon- dolella occurs simultaneously with some important events including the negative shift of δ 13C, change in the ratio of the abundance of cyanobacterial biomarkers versus that of other general bacterial biomarkers and the shallowing of the sea water. Through the investigation of the paleoenvironmental changes and the analysis of the paleoecology of the conodont genus Neogondolella, the authors propose that the major factors for the size reduction of species of the conodont genus Neogondolella are food shortages caused by the mass extinction, the shallowing of the sea water as well as the in- crease in opacity of the sea water during the end Permian. The same phenomenon of Neogondolella size reduction is also observed in preliminary research from the same horizon at Shangsi Section, Sichuan Province. All the evidence suggests that there was a mass extinction that occurred at the horizon of bed 24e, and the evidence supports the viewpoint of a multi-phase mass extinction during the Permian and Triassic transition in South China.展开更多
The Olenekian-Anisian Boundary(OAB)interval is an important time in Earth history,reflecting the last phase of marine ecosystem recovery in the aftermath of the end-Permian mass extinction.Despite this,the Global Stra...The Olenekian-Anisian Boundary(OAB)interval is an important time in Earth history,reflecting the last phase of marine ecosystem recovery in the aftermath of the end-Permian mass extinction.Despite this,the Global Stratotype Section and Point(GSSP)for the base of the Anisian remains undefined.The first appearance of the conodont Chiosella timorensis has been proposed as a potential index for the boundary;however,the discovery of this conodont with ammonoids traditionally considered to be Spathian has generated doubts about its suitability.The taxonomy and relationships of early Anisian conodonts,including species of Chiosella,remain understudied,which leads to difficulties in correlation.New species of Neogondolella(N.gradinarui)and Magnigondolella(M.n.sp.D)have been recognized from the leading GSSP candidate section for the OAB at De?li Caira,and from an additional OAB section at Guandao.Furthermore,several species previously identified in Canada and the USA can be recognized from these sections,improving correlation between Tethys and North America.One of these species may serve as a suitable alternative proxy for the OAB;for instance,N.curva appears just below the first Anisian ammonoids in De?li Caira,and just above the first appearance of C.timorensis in both De?li Caira and Guandao.Continued work on sections other than the candidate sections,and on the taxonomy of species outside of those traditionally proposed as indices,is required.展开更多
基金supported by the National Natural Science Foundation of China(Grant No.40232025)the GeoTurn Group of China University of Geosciences.
文摘This study is based on both a generic and species level investigation of the individual size of the latest Permian conodont Neogondolella Pa elements collected from Meishan Section A, Changxing, Zhejiang Province. In this study, an obvious size reduction of Neogondolella Pa elements within bed 24e of the upper Changxing Limestone is recognized. The size variation of the Neogon- dolella occurs simultaneously with some important events including the negative shift of δ 13C, change in the ratio of the abundance of cyanobacterial biomarkers versus that of other general bacterial biomarkers and the shallowing of the sea water. Through the investigation of the paleoenvironmental changes and the analysis of the paleoecology of the conodont genus Neogondolella, the authors propose that the major factors for the size reduction of species of the conodont genus Neogondolella are food shortages caused by the mass extinction, the shallowing of the sea water as well as the in- crease in opacity of the sea water during the end Permian. The same phenomenon of Neogondolella size reduction is also observed in preliminary research from the same horizon at Shangsi Section, Sichuan Province. All the evidence suggests that there was a mass extinction that occurred at the horizon of bed 24e, and the evidence supports the viewpoint of a multi-phase mass extinction during the Permian and Triassic transition in South China.
文摘The Olenekian-Anisian Boundary(OAB)interval is an important time in Earth history,reflecting the last phase of marine ecosystem recovery in the aftermath of the end-Permian mass extinction.Despite this,the Global Stratotype Section and Point(GSSP)for the base of the Anisian remains undefined.The first appearance of the conodont Chiosella timorensis has been proposed as a potential index for the boundary;however,the discovery of this conodont with ammonoids traditionally considered to be Spathian has generated doubts about its suitability.The taxonomy and relationships of early Anisian conodonts,including species of Chiosella,remain understudied,which leads to difficulties in correlation.New species of Neogondolella(N.gradinarui)and Magnigondolella(M.n.sp.D)have been recognized from the leading GSSP candidate section for the OAB at De?li Caira,and from an additional OAB section at Guandao.Furthermore,several species previously identified in Canada and the USA can be recognized from these sections,improving correlation between Tethys and North America.One of these species may serve as a suitable alternative proxy for the OAB;for instance,N.curva appears just below the first Anisian ammonoids in De?li Caira,and just above the first appearance of C.timorensis in both De?li Caira and Guandao.Continued work on sections other than the candidate sections,and on the taxonomy of species outside of those traditionally proposed as indices,is required.
