https://orcid.org/0000-0003-4827-306X
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Abstract
North China was a key centre of Middle Ordovician stromatoporoid diversification. However, detailed studies of the subsequent Late Ordovician stromatoporoid development in this terrane are lacking; thus, the spatiotemporal development of North Chinese stromatoporoids is poorly understood. The Beiguoshan Formation (middle Katian age, Late Ordovician) contains the youngest Ordovician stromatoporoids in North China, comprising a unique stromatoporoid fauna, consisting of 12 species across 10 genera and three orders of traditional taxonomic groupings: labechiids Rosenella woyuense Ozaki, Citation1938, Pseudostylodictyon poshanense Ozaki, Citation1938, Pseudostylodictyon chunhuaensis (Jiang et al., Citation2011), Labechia sp., Labechiella gondwanense Jeon in Jeon, Liang, Kershaw, Park, and Zhang, Citation2022, Labechiella regularis (Yabe & Sugiyama, Citation1930a); clathrodictyids Clathrodictyon sp. cf. Cl. mammillatum (Schmidt, Citation1858), Camptodictyon amzassensis (Khalfina, Citation1960), Ecclimadictyon tiewadianensis (Jiang et al., Citation2011), Plexodictyon xibeiense Jeon sp. nov., Petriterastroma exililamellatum Jeon and Kershaw gen. et sp. nov.; and the stromatoporellid Simplexodictyon conspicus Jeon and Kershaw sp. nov. This assemblage is distinguished by: (1) succeeding Darriwilian species of North China, (2) few peri-Gondwanan species, and (3) stromatoporoid genera common in Siluro–Devonian assemblages. Plexodictyon and Simplexodictyon species (commonly found in middle Palaeozoic rocks) are here recorded in the Ordovician for the first time. Their stratigraphical occurrence in the middle Katian reveals an interval of absences before their faunal development in the middle Silurian, a stratigraphical gap caused by the Huaiyuan Epeirogeny, which largely shaped and controlled the regional stratigraphy of North China. This unique assemblage of Katian stromatoporoids is not known from other contemporary terranes, supporting the interpretation that North China was separated from the north-eastern peri-Gondwanan regions, thus constituting an independent palaeobiogeographical unit during the Late Ordovician. Early occurrence of these common Siluro–Devonian-type stromatoporoids indicates a prologue of the Ordovician–Silurian stromatoporoid faunal transition in North China, characterized by a decrease in labechiids and rapid diversification of clathrodictyids and related stromatoporoids of typical Silurian types.
http://zoobank.org/urn:lsid:zoobank.org:pub:E8E8C006-D15D-490C-86B8-469E6F02A5A1
Acknowledgements
This study was supported by grants from the Chinese Academy of Sciences (XDB26000000) and the National Natural Science Foundation of China (grant nos. 42030510, 41402013 and J1210006) to Y. D. Zhang and K. Liang. The Alliance of International Science Organizations Scholarship for Young Talents and 2021 Nanjing Municipal Government International Students Scholarship to J. Jeon are acknowledged. We are grateful to Xing-Liang Zhang, Hao Yun (both Northwest University), Luoyang Li (Ocean University of China), D.-J. Lee (Jilin University), S.-J. Choh (Korea University), M. Lee (Korea Polar Research Institute), and H. Park for their field assistance. J. Jeon owes a lot to Ursula Toom (Tallinn University of Technology) and Olga Obut (Trofimuk Institute of Petroleum Geology and Geophysics), for kindly providing references and chances to check Ordovician stromatoporoid type specimens. We are also indebted to Carl Stock and an anonymous reviewer for their constructive comments. This paper is a contribution to IGCP 735 ‘Rocks and the Rise of Ordovician Life: Filling knowledge gaps in the Early Palaeozoic Biodiversification’.
Disclosure statement
No potential conflict of interest was reported by the author(s).
Associate Editor: Ken Johnson