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Flabellophyton, the Only Genus of Ediacaran Fossil Occurring in All Three Taphonomic Modes

Jun 17, 2020

The Ediacara biota (580–541 Ma) documents an important evolutionary episode just before the Cambrian explosion and marks the first appearance of macroscopic and complex multi-cellular life. 

Ediacaran macrofossils are typically preserved in three taphonomic modes: casts/molds in siliciclastic rocks, casts/molds in carbonate rocks, and carbonaceous compressions in black shales. Only a few taxa are known to be preserved in more than one of these taphonomic modes. 

Flabellophyton is a genus that has been previously reported from lower Ediacaran black shale of the Lantian Formation (635-580 Ma) in South China and upper Ediacaran sandstone of the Ediacara Member (560-550 Ma) in South Australia. 

Recently, a joint research team discovered Flabellophyton from upper Ediacaran limestone of the Shibantan Member of the Dengying Formation (551–539 Ma) in South China. This discovery made Flabellophyton the only genus that occurs in all three taphonomic modes. 

The study was conducted by Dr. WAN Bin and his colleagues from the Nanjing Institute of Geology and Palaeontology of the Chinese Academy of Sciences (NIGPAS) and researchers from Virginia Tech and University of California at Riverside of USA and Birbal Sahni Institute of Palaeosciences of India. It was published in Gondwana Research on May 15. 

In the study, they provided a systematic description of Flabellophyton based on material from the Lantian and Dengying formations in South China, recognizing three morphospecies - F. lantianense, F. typicum sp. nov., and F. obesum sp. nov. 

Based on morphological and structural characters, Flabellophyton was reconstructed as an erect epibenthic marine organism attached to sandy, carbonate, and muddy substrates. Its phylogenetic affinity remains ambiguous though it was historically interpreted as an algal fossil. 

Flabellophyton occured in all three taphonomic modes, allowing comparative ecological and taphonomic analyses. 

Taphonomic analysis of Flabellophyton indicated that multiple taphonomic pathways could facilitate the preservation of Ediacaran macrofossils. In particular, the precipitation of authigenic minerals such as pyrite, clay minerals, calcite, and possibly silica might have contributed to the preservation of Flabellophyton in a certain degree of three-dimensionality. 

Environmental factors such as water depth, sediment substrates and redox conditions exerted a strong control through taphonomic and/or paleoecological processes of Flabellophyton. The wide geographicand environmental distribution of Flabellophyton pointed to an unusual capability of Flabellophyton to evolutionarily adapt to different environments. 

As a window into Ediacaran paleoecology, Flabellophyton and other Ediacaran fossils played a crucial role in the construction of epibenthic communities in Ediacaran oceans, and helped to understand the ecologicalmigration and evolutionary expansion from deeper to shallower oceans during the Ediacaran Period. 

 

Paleoecological reconstruction of Flabellophyton from the early Ediacaran Lantian biota, showing a Flabellophyton community on early Ediacaran ocean floor (Image by NIGPAS)

Contact

LIU Yun

Nanjing Institute of Geology and Palaeontology

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A Tale of Three Taphonomic Modes: The Ediacaran Fossil Flabellophyton Preserved in Limestone, Black Shale, and Sandstone

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