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section. In 2017, the Xiaoyangqiao section near the Dayangcha Village, North China, was proposed as the second ASSP for the base of Tremadocian/Lower Ordovician. The first planktonic graptolites can be found right below the Cordylodus lindstromi Conodont Zone in this section. Both ASSPs were approved through supermajority vote by the Subcommission on OrdovicianStratigraphy in 2016 and 2019, respectively. However, in 2021, the International Union of Geological Sciences

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