Pioneer organisms after F-F mass extinction in Dushan region, Guizhou Province, and their significance in establishing new ecosystem |
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摘 要: | After bio-mass extinction, the ecosystems in most areas were damaged seriously and may become an “ecologically barren area” lacking or even without ecosystems. To know what the pioneer organisms would be and their development, and to trace the es- tablishment process of the ecosystems are of great importance for the study of the biological evolution and recovery in aftermath. As one of the “big five” mass extinctions in the geological history, the Late Devonian Frasnian-Famennian (F-F) e…
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收稿时间: | 26 March 2005 |
修稿时间: | 23 November 2005 |
Pioneer organisms after F-F mass extinction in Dushan region, Guizhou Province, and their significance in establishing new ecosystem |
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Authors: | WANG Yue WANG Xunlian SHI Xiaoying |
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Institution: | 1. School of Earth Sciences and Resources, China University of Geosciences, Beijing 100083, China;School of Resources and Environment, Guizhou University, Guiyang 550003, China 2. School of Earth Sciences and Resources, China University of Geosciences, Beijing 100083, China |
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Abstract: | 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 evolution 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 extinction. However, both the recovery and radiation intervals
may be clearly recognized in the Famennian 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 foundation 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 ecosystem”. The establishment of the new ecosystem has laid a foundation for the
recovery of the body fossils thereafter. |
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Keywords: | pioneer organisms reconstruction of ecosystem trace fossils F-F mass extinction Later Devonian Dushan region Guizhou Province China |
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