As reported in a recent issue of Nature (Aug. 15, 2002),two Chinese scientists pinpoint their newly discovered fossil fish as the most direct piece of evi dence on the common ancestry shared by tetrapods (all land... As reported in a recent issue of Nature (Aug. 15, 2002),two Chinese scientists pinpoint their newly discovered fossil fish as the most direct piece of evi dence on the common ancestry shared by tetrapods (all land verte brates including human beings) and lungfish. This latest advance in studying the origin and evolution of early fishes was jointly made by Professor Zhu Min from the CAS Institute of Vertebrate Paleontology & Paleoanthropology and his colleague Yu Xiaobo, now a Professor at the Biology Department of Kean University (New Jersey, USA).……展开更多
四足动物的起源是生物进化过程中的关键问题之一。2006年,美国学者Daeschler E B和Shubin N H在加拿大努纳武特地区南部的埃勒斯米尔岛上发掘了一系列距今3.75亿年的Tiktaalik鱼化石。该鱼与希望螈(Elpisto-stegalian)一样均没有背鳍、...四足动物的起源是生物进化过程中的关键问题之一。2006年,美国学者Daeschler E B和Shubin N H在加拿大努纳武特地区南部的埃勒斯米尔岛上发掘了一系列距今3.75亿年的Tiktaalik鱼化石。该鱼与希望螈(Elpisto-stegalian)一样均没有背鳍、没有鳃盖、子鳃盖、外肩胛骨;而具有宽大的背腹性明显的扁平颅骨,以及位于颅骨背面的眼睛,还具有成对的额骨、微鼻孔和位于末端的口,并具备了四足动物的一些特征,诸如较大的通气孔、可活动的颈部、伏瓦状排列的肋骨,胸鳍出现了挠骨的分化,并有骨质关节。这一发现填补了从海洋动物到四足动物的空白。展开更多
The non-marine strata of the Ypresian Naredi Formation have been deposited and intermittently pedogenized after the culmination of the Early Eocene Climatic Optimum(EECO).This continental interval comprises intercalat...The non-marine strata of the Ypresian Naredi Formation have been deposited and intermittently pedogenized after the culmination of the Early Eocene Climatic Optimum(EECO).This continental interval comprises intercalation of laterite and palaeosol horizons developed by cyclic episodes of erosion,subaerial exposure,and deposition.The palaeopedological analyses investigate the morphological and micromorphological features evidencing repeated subaerial exposure and consequently moderate to well-developed palaeosol horizons.The topmost laterite bed records an intensely bioturbated ichnofabric(consisting of the root traces and the composite ichnotaxa of lungfish aestivation burrows,Macanopsis(possible arachnid burrows),and Skolithos.The pedogenized shale horizons contain the paucispecific Camborygma-root trace ichnofabric with highly localized patchy preservation of Camborygma symplokonomos,Camborygma eumekenomos,and rhizoturbation.The ichnospecies variation of Camborygma along with the ichnofabric analyses led to the demarcation of stratigraphic horizons and evaluation of the palaeowater-table fluctuations vis-a-vis the low-order allocyclicity,the ethology of producers,and the depositional setting.The paucispecific suite of trace fossils refers to the Camborygma Ichnofacies,where the substrate is intermittently pedogenized and lateritized with upward increasing thickness of beds and intensity of pedogenesis,lateritization,ichnodiversity,and ichnoabundance.Hence,as an expression of high-frequency(interpreted as 5th-order)stratigraphic fluctuations within an early Falling Stage Systems Tract(FSST),a hot palaeoclimate with seasonality varying between humid inundated to dry desiccated conditions is interpreted with the palaeowater table being the base-level control.It culminates with the driest condition at the top with the thickest laterite development associated with the RAeMaS ichnofabric.With the onset of early transgression as documented in the overlying marine deposits of the Bartonian Harudi Formation,the top of the studied interval marks an induced subaerial unconformity.展开更多
文摘 As reported in a recent issue of Nature (Aug. 15, 2002),two Chinese scientists pinpoint their newly discovered fossil fish as the most direct piece of evi dence on the common ancestry shared by tetrapods (all land verte brates including human beings) and lungfish. This latest advance in studying the origin and evolution of early fishes was jointly made by Professor Zhu Min from the CAS Institute of Vertebrate Paleontology & Paleoanthropology and his colleague Yu Xiaobo, now a Professor at the Biology Department of Kean University (New Jersey, USA).……
文摘四足动物的起源是生物进化过程中的关键问题之一。2006年,美国学者Daeschler E B和Shubin N H在加拿大努纳武特地区南部的埃勒斯米尔岛上发掘了一系列距今3.75亿年的Tiktaalik鱼化石。该鱼与希望螈(Elpisto-stegalian)一样均没有背鳍、没有鳃盖、子鳃盖、外肩胛骨;而具有宽大的背腹性明显的扁平颅骨,以及位于颅骨背面的眼睛,还具有成对的额骨、微鼻孔和位于末端的口,并具备了四足动物的一些特征,诸如较大的通气孔、可活动的颈部、伏瓦状排列的肋骨,胸鳍出现了挠骨的分化,并有骨质关节。这一发现填补了从海洋动物到四足动物的空白。
基金Science and Engineering Research Board(SERB),Government of India(grant#CRG/2018/000259 to SDG)Industrial Research and Consultancy Centre(IRCC),IIT Bombay(seed grant#RD/0517-IRCCSH0-035 to SDG and final-year scholarship to MD)+1 种基金IITB and Ministry of Education,Government of India(doctoral scholarship for MD)Council of Scientific&Industrial Research(CSIR)(doctoral scholarship for RD.
文摘The non-marine strata of the Ypresian Naredi Formation have been deposited and intermittently pedogenized after the culmination of the Early Eocene Climatic Optimum(EECO).This continental interval comprises intercalation of laterite and palaeosol horizons developed by cyclic episodes of erosion,subaerial exposure,and deposition.The palaeopedological analyses investigate the morphological and micromorphological features evidencing repeated subaerial exposure and consequently moderate to well-developed palaeosol horizons.The topmost laterite bed records an intensely bioturbated ichnofabric(consisting of the root traces and the composite ichnotaxa of lungfish aestivation burrows,Macanopsis(possible arachnid burrows),and Skolithos.The pedogenized shale horizons contain the paucispecific Camborygma-root trace ichnofabric with highly localized patchy preservation of Camborygma symplokonomos,Camborygma eumekenomos,and rhizoturbation.The ichnospecies variation of Camborygma along with the ichnofabric analyses led to the demarcation of stratigraphic horizons and evaluation of the palaeowater-table fluctuations vis-a-vis the low-order allocyclicity,the ethology of producers,and the depositional setting.The paucispecific suite of trace fossils refers to the Camborygma Ichnofacies,where the substrate is intermittently pedogenized and lateritized with upward increasing thickness of beds and intensity of pedogenesis,lateritization,ichnodiversity,and ichnoabundance.Hence,as an expression of high-frequency(interpreted as 5th-order)stratigraphic fluctuations within an early Falling Stage Systems Tract(FSST),a hot palaeoclimate with seasonality varying between humid inundated to dry desiccated conditions is interpreted with the palaeowater table being the base-level control.It culminates with the driest condition at the top with the thickest laterite development associated with the RAeMaS ichnofabric.With the onset of early transgression as documented in the overlying marine deposits of the Bartonian Harudi Formation,the top of the studied interval marks an induced subaerial unconformity.
