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1 January 2020 Graptolites from Silurian (Llandovery Series) Sedimentary Deposits Attributed to a Forearc Setting, Co to Formation, Co to Archipelago, Northeast Vietnam
Muhammad Aqqid Saparin, Mark Williams, Jan Zalasiewicz, Toshifumi Komatsu, Adrian Rushton, Hung Dinh Doan, Ha Thai Trinh, Hung Ba Nguyen, Minh Trung Nguyen, Thijs R. A. Vandenbroucke
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Abstract

Newly collected graptolites from the Co To Formation, Co To archipelago, NE Vietnam, comprise assemblages indicative of two biostratigraphical levels within the lower Silurian, Llandovery Series, Telychian Stage: the co-occurrence of Spirograptus turriculatus and Torquigraptus proteus? suggests an interval most likely within the upper part of the Spirograptus turriculatus Biozone or ‘Monograptuscrispus Biozone, whilst Oktavites spiralis and Monoclimacis cf. subgeinitzi identify the Oktavites spiralis Biozone. The graptolites provide important biostratigraphical evidence for the age of the upper part of the lower Co To Formation, biostratigraphical ties between the NE Vietnamese succession of the Bac Bo Region and graptolite assemblages of the Long Dai Formation in the Viet-Lao Region of central Vietnam, and include the new species Monograptus hamulus sp. nov. co-occurring with S. turriculatus, which is perhaps an ancestral form to the later Telychian species Monograptus drepanoformis. We also report the first chitinozoans, including Belonechitina, from the Co To Formation.

© by the Palaeontological Society of Japan
Muhammad Aqqid Saparin, Mark Williams, Jan Zalasiewicz, Toshifumi Komatsu, Adrian Rushton, Hung Dinh Doan, Ha Thai Trinh, Hung Ba Nguyen, Minh Trung Nguyen, and Thijs R. A. Vandenbroucke "Graptolites from Silurian (Llandovery Series) Sedimentary Deposits Attributed to a Forearc Setting, Co to Formation, Co to Archipelago, Northeast Vietnam," Paleontological Research 24(1), 26-40, (1 January 2020). https://doi.org/10.2517/2019PR003
Received: 10 December 2018; Accepted: 5 March 2019; Published: 1 January 2020
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KEYWORDS
biostratigraphy
Chitinozoans
Graptolites
Llandovery Series
Silurian
Vietnam
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