Early Devonian polygnathids of Northeast Asia and correlation of Pragian/Emsian strata of the marginal seas of Angarida

• Published in: Bulletin of Geosciences
• Main Authors: Baranov, V., Slavík, L. (Ladislav), Blodgett, R. B.
• Format: Article in Journal/Newspaper
• Language: English
• Published: 2014
• Subjects: Early Devonian; Pragian/Emsian strata; Angarida; Taimyr
• Online Access: https://doi.org/10.3140/bull.geosci.1483; http://hdl.handle.net/11104/0234751

In late Pragian and early Emsian strata of the Izvestkovyi Karier – II section of Northeast Asia is found a continuous sequence of representatives of the family Polygnathidae which testify to the synthetic nature of the currently used conodont zonal scales. In this time interval are recognized three phylogenetic lineages of polygnathids: Polygnathus sobolevi → Po. ivanowskyii, Polygnathus kitabicus → Po. bardashevi and Polygnathus settedabanicus → Po. nothoperbonus. Fifteen species of polygnathids including mostly newly described taxa are documented here: Polygnathus alkhovikovae sp. nov., Po. arthuri sp. nov., Po. bardashevi sp. nov., Po. dehiscens (Philip & Jackson, 1967) late morphotype, Po. excavatus (Carls & Gandl, 1969), Po. ivanowskyii sp. nov., Po. karsteni sp. nov., Po. kitabicus (Yolkin et al., 1994), Po. lezhoevi sp. nov., Po. michaelmurphyi sp. nov., Po. nothoperbonus (Mawson, 1987), Po. perbonus (Philip, 1966), Po. sobolevi Bardashev, Weddige & Ziegler, 2002, Po. settedabanicus sp. nov., and Po. yakutensis sp. nov. Early Emsian time in Northeast Asia is characterized by an intense speciation and radiation within its conodont fauna during a relatively short interval between the Polygnathus excavatus and Polygnathus nothoperbonus zones. The Pragian Stage (Middle Early Devonian) is characterized by a maximum transgression that led to increased migration of faunal associations of tabulate and rugose corals, brachiopods and conodonts in the marginal seas of Angarida. The position of the lower and upper boundaries of the Pragian Stage in this region is clarified and their correlations are shown with the adjoining Verkhoyansk-Chukotsk (Kolyma region), Taimyr, West Siberian, and Altai-Sayan marginal seas.