Jurassic planktic foraminifera from the Polish Basin

Abstract

Abstract. Jurassic (Bathonian–Oxfordian) planktic foraminifera from the epicontinental strata of the Polish Basin have been investigated. The palaeoecology, palaeobiogeography, and biostratigraphical potential of the recorded taxa are discussed. Four species are recorded: Conoglobigerina helvetojurassica (Haeusler, 1881), Globuligerina balakhmatovae (Morozova, 1961), G. bathoniana (Pazdrowa, 1969), and G. oxfordiana (Grigelis, 1958). This assemblage is probably the most diverse of those described to date from the epicontinental areas of Europe. The recorded taxa are thought to represent three different ecological morphotypes. The clear relationship between transgressive–regressive facies and the palaeobiogeography of the recorded planktic foraminifera indicates a morphotype-related depth–distribution pattern in which small, simple, globular-chambered morphotypes occupied shallow waters whereas slightly larger, more complex forms, or those with hemispherical chambers, inhabited deeper and more open-water environments.

Triassic and Jurassic possible planktonic foraminifera and the assemblages recovered from the Ogrodzieniec Glauconitic Marls Formation (uppermost Callovian and lowermost Oxfordian, Jurassic) of the Polish Basin

“…A significant number of these steinkerns from the strata adjacent to the Callovian-Oxfordian boundary represent planktonic taxa that have a simple morphology, ∼ four chambers in the final whorl and a quite variable spire height. Examples of these taxa from the Polish Basin are presented by Pazdrowa (1969), Hart et al (2012) and Gajewska et al (2021). The assemblages of planktonic foraminifera from the Polish Basin are, therefore, significant in the discussion of the evolution of Jurassic plankton, even if their lineages petered out in the mid-Cretaceous and were replaced by the calcitic taxa.…”

“…These individuals have a variable spire height and thickness of wall, with a characteristic ∼ four inflated chambers in the final whorl. In the Bathonian strata of the Ogrodzieniec area of Poland, undoubted planktonic foraminifera are present, including Conoglobigerina bathoniana (Pazdrowa, 1969;Hart et al, 2012;Kendall et al, 2020;Gajewska et al, 2021).…”

“…These samples, when processed at the University of Plymouth, yielded the typical steinkerns that had been seen in the collections of the Austrian Geological Survey and in the samples collected by Wendy Hudson and Michael Simmons. The planktonic foraminifera are illustrated in the paper by Gajewska et al (2021), and some of the benthic foraminifera are illustrated here (see Appendix B). Benthic foraminifera are quite difficult to determine as glauconitic steinkerns as one can normally only identify the trochospiral chamber arrangement, height of spire and numbers of chambers.…”

An updated suprageneric classification of planktic foraminifera after growing evidence of multiple benthic-planktic transitions

“…Others became also successful in the oceanic realm, mainly in continental margins. The neritic environment, probably close to continental margins, was the preferred habitat for the first Jurassic favuselloids, i.e., Conoglobigerina and Globuligerina (Gordon, 1970;Hart et al, 2002Hart et al, , 2003Hudson et al, 2009;Gradstein et al, 2017;Kendall et al, 2020;Gajewska et al, 2021). Protoheterohelix and its closest descendants (e.g., Planoheterohelix Georgescu & Huber, 2009) were inferred to be upper mixed layer dwellers (Nederbragt, 1991;Nederbragt et al, 1998).…”