Palaeobiogeography of early planktonic foraminifera

Abstract

Over the last 50 years, our knowledge of early planktonic foraminifera has changed markedly. In 1958 Grigelis described “Globigerina oxfordiana” from the Upper Jurassic of Lithuania and this has, subsequently, become identified as one of the most geographically widespread of Jurassic planktonic taxa. There is a danger in that many authors identify any planktonic foraminiferid from the Jurassic as this taxon, rather than consider the alternative species described in the literature. In the period from 1967 to 1973, however, Dr W. Fuchs (Austria) identified a number of new taxa from the Triassic and Jurassic of Austria and the Jurassic of Poland and claimed that the history of planktonic foraminifera began in the Triassic. Following a long re-investigation of all his material in the Geologische Bundesanstalt in Vienna by the authors it appears that one of his new genera, Praegubkinella, was probably the ancestor of Conoglobigerina in the Toarcian (Early Jurassic). The first conoglobigerinids have been described from Toarcian – Aalenian – Bajocian strata in Central and Eastern Europe (including parts of the Former Soviet Union). The palaeobiogeography of Conoglobigerina and other related genera such as Globuligerina, Haeuslerina and Compactogerina are discussed and the problems yet to be resolved (e.g., records of “planktonic” taxa in the Triassic/Jurassic offshore N.W. Australia) are documented. The distribution (and evolution) of the Jurassic and Early Cretaceous planktonic foraminifera appear to be related to sea level highstands and continental fragmentation, especially in the earliest Cretaceous.

A reassessment of ‘<i>Globigerina bathoniana</i>’ Pazdrowa, 1969 and the palaeoceanographic significance of Jurassic planktic foraminifera from southern Poland

“…It has previously been noted (Hudson et al, 2009) that there is a widespread (Poland, Germany, UK, etc.) occurrence of planktic foraminifera in the uppermost Callovian to lowermost Oxfordian (e.g.…”

“…In the mid-Jurassic the situation was very different and the positions of the ACd and CCd were, almost certainly, completely different. The pteropods had not evolved and the planktic foraminifera probably evolved in the Toarcian (Hart et al, 2003;Hudson et al, 2009), and remained a low diversity assemblage until the earliest Cretaceous (Hart et al, 2002). These early planktic foraminifera were aragonitic in composition (Simmons et al, 1997) and this is in keeping with an origin within the Aragonite ll Ocean of Stanley & Hardie (1998), Stanley (2006) and de Vargas et al (2007).…”

“…Evolving from benthic ancestors in the mid-Toarcian, the planktic foraminifera dispersed rapidly within the Jurassic Tethys/Peri-Tethys seaway (Hudson et al, 2009). In many areas of this seaway the low-diversity planktic foraminiferal assemblage was almost the only provider of CaCO 3 (in the form of aragonite) to the sea floor.…”

Global bioevents and the Cretaceous/Paleogene boundary in Texas and Alabama: Stratigraphy, correlation and ocean acidification

“…While the calcareous nannofossils appeared in the Triassic, they did not colonise the open ocean in large numbers until the post-Toarcian (Bown et al, 2004;Bown, 2005). This is almost the same time that the planktic foraminifers appeared in the Tethys Ocean (Wernli, 1995;Wernli and Görög, 1999;Hart et al, 2003Hart et al, , 2012aHudson et al, 2009). The planktic foraminifers did not, however, become diverse and abundant until the Early Cretaceous (Premoli Silva and Sliter, 1999;Hart, 1999;Hart et al, 2002).…”

Seeking a better life in the plankton

“…Planktic foraminifers of the Jurassic occupied shallow seas and hugged the margins of Tethys (12)(13)(14). They expanded their range in the Early Cretaceous (15), but then experienced an explosion of diversity and morphologic form during the mid-Cretaceous that continued through the Late Cretaceous (e.g., refs.…”