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Data from: Algal affinity and possible life cycle of the early Cambrian acritarch Yurtusia uniformis from South China

Citation

Shang, Xiaodong; Liu, Pengju; Moczydłowska, Małgorzata; Yang, Ben (2021), Data from: Algal affinity and possible life cycle of the early Cambrian acritarch Yurtusia uniformis from South China, Dryad, Dataset, https://doi.org/10.5061/dryad.ttdz08kv0

Abstract

Abundant, well-preserved specimens of spheroidal organic-walled microfossil Yurtusia uniformis are reported from the basal Cambrian Yanjiahe Formation in the Changyang area of Hubei Province, South China. Thin and hollow processes extend between the double walls of the vesicle. The single to multiple internal bodies within the vesicle cavity are observed in the genus for the first time, representing reproductive structures (dividing daughter cells). A small circular perforation may occur on the vesicle wall to release the internal bodies. Morphological analyses of specimens preserved at various life stages reveal that processes gradually became longer as the vesicle grew in size. The internal bodies (daughter cells) underwent several successive divisions within the vesicle, which was accompanied by a simultaneous growth of both the vesicle and processes. The regular growth of cells, formation and release of daughter cells, and the remarkable morphological similarity between extant algae and the studied microfossils suggest that Yurtusia uniformis is likely a green microalga that may be closely related to the Trebouxiophyceae or even Chlorellales (Chlorophyta). The growth and reproductive mode of individuals indicates that Y. uniformis is an actively growing vegetative cell of microalgae, rather than a metabolically inert cyst or resting spore. The life cycle of Y. uniformis involving vegetative growth and asexual reproduction is proposed on the basis of life histories of modern chlorophytes. The multiple internal cells may represent autospores produced by a mature autosporangium in the asexual reproduction, which subsequently developed into separate young vegetative cells after their release from the opened autosporangium.

Methods

Abundant, well-preserved specimens of spheroidal organic-walled microfossil Yurtusia uniformis are reported from the basal Cambrian Yanjiahe Formation in the Changyang area of Hubei Province, South China. Five samples of chert bands derived from the interval of argillaceous dolostone about 24 m above the base of the Yanjiahe Fm were studied in petrographic thin sections. The samples were cut parallel to the bedding planes and polished into ~50 micron thicknesses. Organic-walled microfossils were examined under a Carl Zeiss Axio Imager.A2 transmitted light microscope (LM) and digitally photographed by an attached Carl Zeiss AxioCam MRc5 camera. Their dimensions were measured using AxioVision Rel. 4.8 software. All thin sections with studied specimens are reposited in the collections of the Institute of Geology, Chinese Academy of Geological Sciences, Beijing, China, and they are assigned to the catalogue number with the prefix IGCAGS. The dataset includes the measurements of vesicle diameter and process length on the studied specimens.

Funding

National Natural Science Foundation of China, Award: 41872024

National Natural Science Foundation of China, Award: 41902019

China Postdoctoral Science Foundation, Award: 2019M660742

Chinese Academy of Sciences, Award: Strategic Priority Research Program (B), XDB 26000000

National Key Research and Development Program of China, Award: 2016YFC0601001

China Geological Survey, Award: DD20190008