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Basal Cambrian microfossils from the Yangtze Gorges area (South China) and the Aksu area (Tarim block, northwestern China)

Published online by Cambridge University Press:  20 May 2016

Lin Dong ,
Shuhai Xiao ,
Bing Shen ,
Chuanming Zhou ,
Guoxiang Li  and
Jinxian Yao
Lin Dong
Affiliation:
Department of Geosciences, Virginia Polytechnic Institute and State University, Blacksburg 24061, ,
Shuhai Xiao
Affiliation:
Department of Geosciences, Virginia Polytechnic Institute and State University, Blacksburg 24061, ,
Bing Shen
Affiliation:
Department of Geosciences, Virginia Polytechnic Institute and State University, Blacksburg 24061, ,
Chuanming Zhou
Affiliation:
State Key Laboratory of Paleobiology and Stratigraphy, Nanjing Institute of Geology and Palaeontology, Chinese Academy of Sciences, Nanjing 210008
Guoxiang Li
Affiliation:
State Key Laboratory of Paleobiology and Stratigraphy, Nanjing Institute of Geology and Palaeontology, Chinese Academy of Sciences, Nanjing 210008
Jinxian Yao
Affiliation:
College of Life Sciences, Peking University, Beijing 100871, China
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Abstract

The basal Cambrian marks the beginning of an important chapter in the history of life. However, most paleontological work on the basal Cambrian has been focused on skeletal animal fossils, and our knowledge about the primary producers—cyanobacteria and eukaryotic phytoplankton (e.g., acritarchs)—is limited. In this research, we have investigated basal Cambrian acritarchs, coccoidal microfossils, and cyanobacteria preserved in phosphorites and cherts of the Yanjiahe Formation in the Yangtze Gorges area (South China) and the Yurtus Formation in the Aksu area (Tarim Block, northwestern China). Our study confirms the occurrence in these two formations of small acanthomorphic acritarchs characteristic of the basal Cambrian Asteridium–Comasphaeridium–Heliosphaeridium (ACH) assemblage. These acritarchs include abundant Heliosphaeridium ampliatimi (Wang, 1985) Yao et al., 2005, common Yurtusia uniformis n. gen. and n. sp., and rare Comasphaeridium annulare (Wang, 1985) Yao et al., 2005. In addition, these basal Cambrian successions also contain the clustered coccoidal microfossil Archaeophycus yunnanensis (Song in Luo et al., 1982) n. comb., several filamentous cyanobacteria [Cyanonema majus n. sp., Oscillatoriopsis longa Timofeev and Hermann, 1979, and Siphonophycus robustum (Schopf, 1968) Knoll et al., 1991], and the tabulate tubular microfossil Megathrix longus L. Yin, 1987a, n. emend. Some of these taxa (e.g., H. ampliatum, C. annulare, and M. longus) have a wide geographic distribution but occur exclusively in basal Cambrian successions, supporting their biostratigraphic importance. Comparison between the stratigraphic occurrences of microfossils reported here and skeletal animal fossils published by others suggests that animals and phytoplankton radiated in tandem during the Cambrian explosion.

Type
Research Article
Information
Journal of Paleontology , Volume 83 , Issue 1 , January 2009 , pp. 30 - 44
Copyright
Copyright © The Paleontological Society

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