摘要
After mass extinctions, most areas became “ecologically barren areas” lacking or even without ecosystem over an extensive region. Studying the pioneer organisms and the reconstruction process of a new ecosystem in the “ecologically barren area” is very important for revealing the evo- lution after bio-mass extinctions. In the Dushan region, Guizhou Province, China, the trace fossils appeared and flourished evidently earlier than body fossils after Frasnian-Famennian (F-F) mass extinction. The pioneer organisms and pathfinders in the “ecologically barren areas” are the trace-makers that are deposit-feeders with relatively simple structure and conformation on or near the deposit surface. The trace-makers have undergone an evolutionary process that their trace structures changed from simple to complex, and their living and moving areas and spaces enlarged from linear to planar and then to three-dimension spaces. Those characters show that the ability of the trace-makers to deposits and their efficiency of looking for food have been enhanced gradually and that those trace-makers constructed gradually a base for the new ecosystem. This process is similar to that of the trace fossils near the Precambrian-Cambrian boundary. In the Dushan area, only the recovery intervals have been identified for the Famennian body fossils, with no eminent radiation interval recognizable due to the Devonian-Carboniferous (C-D) mass ex- tinction. However, both the recovery and radiation intervals may be clearly recognized in the Famen- nian trace fossils based on their conformation and diversity. The evolution and diversification of the trace fossils in the “ecologically barren area” is considered to have played a role of necessary foun- dation for the recovery of body fossils in the ecological chain. With the gradual disappearance of the unfavourable environment factors resulting in the F-F mass extinction, a new ecosystem was reconstructed in the “ecologically barren area” through a three-step process from the “original ecosystem” to “elementary ecosystem” and finally to the “developed eco- system”. The establishment of the new ecosystem has laid a foundation for the recovery of the body fossils thereafter.
After mass extinctions, most areas became ''ecologically barren areas'' lackingor even without ecosystem over an extensive region. Studying the pioneer organisms and thereconstruction process of a new ecosystem in the ''ecologically barren area'' is very important forrevealing the evo-lution after bio-mass extinctions. In the Dushan region, Guizhou Province, China,the trace fossils appeared and flourished evidently earlier than body fossils afterFrasnian-Famennian (F-F) mass extinction. The pioneer organisms and pathfinders in the ''ecologicallybarren areas'' are the trace-makers that are deposit-feeders with relatively simple structure andconformation on or near the deposit surface. The trace-makers have undergone an evolutionary processthat their trace structures changed from simple to complex, and their living and moving areas andspaces enlarged from linear to planar and then to three-dimension spaces. Those characters show thatthe ability of the trace-makers to deposits and their efficiency of looking for food have beenenhanced gradually and that those trace-makers constructed gradually a base for the new ecosystem.This process is similar to that of the trace fossils near the Precambrian-Cambrian boundary. In theDushan area, only the recovery intervals have been identified for the Famennian body fossils, withno eminent radiation interval recognizable due to the Devonian-Carboniferous (C-D) mass extinction.However, both the recovery and radiation intervals may be clearly recognized in the Famennian tracefossils based on their conformation and diversity. The evolution and diversification of the tracefossils in the ''ecologically barren area'' is considered to have played a role of necessaryfoundation for the recovery of body fossils in the ecological chain. With the gradual disappearanceof the unfavourable environment factors resulting in the F-F mass extinction, a new ecosystem wasreconstructed in the ''ecologically barren area'' through a three-step process from the ''originalecosystem'' to ''elementary ecosystem'' and finally to the ''developed ecosystem''. The establishment ofthe new ecosystem has laid a foundation for the recovery of the body fossils thereafter.
基金
supported by the National Natural Science F oundation of China(Grant No.40172014)
the Guizhou University Foundation.
