Pseudolamarckina pseudorjasanensis Dain, 1967 (Foraminifera) as a Kimmeridgian marker species and its significance for biostratigraphy, palaeoecology and palaeobiogeography

• Published in: Polar Research
• Main Authors: Clémentine Peggy Anne-Marie Colpaert, Boris Leonidovich Nikitenko
• Format: Article in Journal/Newspaper
• Language: English
• Published: Norwegian Polar Institute 2019
• Subjects: Foraminifera; systematics; Arctic; Jurassic; biogeography; palaeoenvironments; envir; archeo; Foraminifera*; Polar Research; Siberia
• Online Access: https://doi.org/10.33265/polar.v38.3461; https://doaj.org/article/523c87e1f1b14887b7e218ab6e8aee9f

This study presents a taxonomical review of the species Pseudolamarckina pseudorjasanensis Dain, 1967 collected at different sampling levels from the central and northern parts of European Russia and from Western Siberia. Morphological and biometrical analyses show that P. pseudorjasanensis is characterized by wide intraspecific variabilities and may encompass various previously described Kimmeridgian species of the genus Pseudolamarckina. The first appearance of P. pseudorjasanensis is recorded from the latest Early Kimmeridgian of sub-Mediterranean to Arctic regions. Furthermore, P. pseudorjasanensis appears to be the marker species of the foraminiferal JF41 Zone in Kimmeridgian sections of sub-boreal, boreal and Arctic regions. This JF41 Zone is particularly significant for interregional correlations. Finally, P. pseudorjasanensis was widespread across the Kimmeridgian basins of the Northern Hemisphere and was associated with environments predominantly located in the middle sublittoral zone.