TY - JOUR AU - Colpaert , ClĂ©mentine Peggy Anne-Marie AU - Leonidovich Nikitenko , Boris PY - 2019/03/05 Y2 - 2024/03/28 TI - <em>Pseudolamarckina pseudorjasanensis </em>Dain, 1967 (Foraminifera) as a Kimmeridgian marker species and its significance for biostratigraphy, palaeoecology and palaeobiogeography JF - Polar Research JA - POLAR VL - 38 IS - 0 SE - Research Articles DO - 10.33265/polar.v38.3461 UR - https://polarresearch.net/index.php/polar/article/view/3461 SP - AB - 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. ER -