The Early Devonian (Emsian) acrotretid microbrachiopod Opsiconidion minor Popov, 1981, from the Alaska/Yukon Territory border and Novaya Zemlya

• Published in: Estonian Journal of Earth Sciences
• Main Authors: Holmer, Lars E., Blodgett, Robert B., Liang, Yue, Zhang, Zhifei
• Format: Article in Journal/Newspaper
• Language: English
• Published: Uppsala universitet, Paleobiologi 2020
• Subjects: Brachiopoda; Lingulata; Acrotretida; Biernatidae; Devonian; Emsian; Novaya Zemlya; Russia; Alaska; Yukon Territory; Other Earth and Related Environmental Sciences; Annan geovetenskap och miljövetenskap; Canada; Ogilvie; Yukon
• Online Access: http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-415206; https://doi.org/10.3176/earth.2020.10

New records of the poorly known acrotretid (Biernatidae) microbrachiopod Opsiconidion minor Popov are described from middle Emsian strata of the Ogilvie Formation in east­central Alaska and the adjacent Yukon Territory, Canada, and compared with new better­preserved topotypes from the late Early Devonian (Emsian) of Novaya Zemlya, Russia. In Alaska O. minor occurs together with fragmentary material of Lingulipora sp. and an indeterminate discinid. The only other previous record of O. minor, outside the type area, comes from the Early to ?Middle Devonian (Pragian to ?Givetian) of Australia (Victoria and NSW). Opsiconidion Ludvigsen is a stratigraphically extremely long­ranging and cosmopolitan acrotretid, which exhibits a remarkable conservatism; the morphology of the ventral valve remains essentially unchanged from the earliest Ordovician (Darriwilian) records to the Devonian.