Description of new Permian orthocerid forms from Gufeng Formation of South China (the Yangtze Craton) and their palaeobiogeographic implications in the Palaeotethys

ABSTRACT

Orthocerids from the Upper Gufeng Formation, Guadalupian (middle Permian), from Anhui Province (China) are described for the first time in this article. The specimens are mainly Pseudorthoceratidae characterised by slender orthocones that have been studied under CT-Scan. A new genus and species have been described, Houdongoceras chaohuensis gen. et sp. nov., with seven morphotypes that presumably relate to new ones. Seventeen per cent of the specimens have epibiotic bacterial colonies associated indicating suboxic environments restating redox conditions during their deposition. This is also the first report of Permian macrofossils presenting bacterial colonies in China. This fauna is interpreted as autochthonous or parautochthonous which originally lived nektobenthically in shallow marine waters above the sediments or close to the sea bottom on the eastern margin of the Palaeotethys Ocean during the late Guadalupian faunal crisis.

KEYWORDS:

• Gufeng Formation
• Guadalupian
• Anhui province
• Pseudorthoceratidae
• bacterial colonies
• Palaeotethys

Acknowledgments

This research has been supported by the Chinese Academy of Sciences (grant XDB26000000) and the Natural Science Foundation of China. We thank Dr Congjun Yin and Miss Suping Wu of Nanjing Institute of Geology and Palaeontology for the supporting of CT technology, Dr Kuidong Zhao of China University of Geosciences (Wuhan) and Xiangyuan Chen for collecting samples in 2006 and 2017, respectively, Dr Tomasz Goral for his assistance at the SEM at the Natural History Museum (NHM), London, and Kevin Webb, NHM science photographer for most of the photographs illustrated in this paper. I would also like to acknowledge Dr John Taylor, NHM scientific associate, Dr Olev Vinn, University of Tartu (Estonia), Dr Iván Cortijo, UNESCO Geopark Villuercas-Ibores-Jara (Spain) and Dr Mónica Martí Mus, University of Extremadura (Spain) for useful comments on taxonomy; Dr Jeremy Young (University College London), Dr Alberto Perez-Huerta (University of Alabama) and Dr Giles Miller and Dr Tim Ewin from the NHM for advice discarding possible microfossils and assisting with ammonium chloride, respectively; Dr Tsuyoshi Ito (Geological Survey of Japan, AIST) and an anonymous reviewer for improving this manuscript. Dr Consuelo Sendino, from the Natural History Museum, London, benefited from the support of Nanjing University.

Disclosure statement

The authors declared no potential conflicts of interest with respect to the research, authorship, and/or publication of this article.

Additional information

Funding

This work was supported by the Chinese Academy of Sciences Key Project [XDB26000000].