Schizosphaerella size and abundance variations across the Toarcian Oceanic Anoxic Event in the Sogno Core (Lombardy Basin, Southern Alps)

Suboxic conditions prevailed during the Toarcian Oceanic Anoxic Event in the Alpine-Mediterranean Tethys: The Sogno Core pelagic record (Lombardy Basin, northern Italy)

“…A combination of higher fertility and disruption of surface-water stability triggered a rapid shift in nannofossil assemblages. Specifically, the Fish Level is characterized by an increase in abundance of Lotharingius and Biscutum suggesting mesotrophic conditions further corroborated by the drop in abundance of the presumed oligotrophic Schizosphaerella, although its crisis is possibly the result also of ocean acidification (Erba, 2004;Casellato and Erba, 2015;Faucher et al, 2022).…”

Morphometric changes in two Late Cretaceous calcareous nannofossil lineages support diversification fueled by long-term climate change

“…Cyclic changes in the size of Pliensbachian Crepidolithus crassus have been related to an orbital control, but the primary causes evoked to explain these features are changes in water turbidity and nutrient recycling in the photic zone via orbitally-controlled storm intensity (Suchéras-Marx et al, 2010). Large Pliensbachian nannolith Schizosphaerella size changes have been interpreted as variations in abundance of three distinct morphotypes as a response to variations in temperature and proximity to the coastline (Peti & Thibault, 2017;Peti et al, 2021), whereas the drop in size of this same taxon across the Toarcian Oceanic Anoxic Event has been interpreted as a response to a calcification crisis (Suan et al, 2010;Clémence et al, 2015;Faucher et al, 2022). Changes in the size of Early to Middle Jurassic coccolith Lotharingius species might reflect the opposition between stable environmental conditions favoring large specimens versus periods dominated by ecological stress favoring small specimens (Ferreira et al, 2017).…”

“…Morphological changes in calcareous nannofossils have been the subject of numerous studies across their evolutionary history in the Meso-Cenozoic. Perhaps due to better preserved records, Cenozoic biometric studies are abundant, while Mesozoic studies have focused mostly on specific intervals such as the Early to Middle Jurassic (Suchéras-Marx et al, 2010;Suan et al, 2010;Peti & Thibault, 2017;Peti et al, 2021;Menini et al, 2021;Faucher et al, 2022;López-Otálvaro et al, 2012;Ferreira et al, 2017) or Early to mid-Cretaceous (Bornemann & Mutterlose, 2006;Barbarin et al, 2012;Lübke & Mutterlose, 2016;Bottini & Faucher, 2020;Wulff et al, 2020). In comparison to the latter periods, and considering that the Santonian to Maastrichtian interval bears the highest diversity within the overall evolutionary history of calcareous nannoplankton (Bown et al 2004), this significant part of the Late Cretaceous has been the subject of relatively few biometric studies mostly focused on Arkhangelskiellaceae and the Eiffelithus lineages (Girgis, 1987;Faris 1995;Thibault et al, 2004;Linnert & Mutterlose, 2009;Shamrock & Watkins, 2009;Thibault, 2010;Linnert et al, 2014).…”

Morphometric changes in two Late Cretaceous calcareous nannofossil lineages support diversification fueled by long-term cooling

“…Cyclic changes in the size of Pliensbachian Crepidolithus crassus have been related to an orbital control, but the primary causes evoked to explain these features are changes in water turbidity and nutrient recycling in the photic zone via orbitally-controlled storm intensity (Suchéras-Marx et al, 2010). Large Pliensbachian nannolith Schizosphaerella size changes have been interpreted as variations in abundance of three distinct morphotypes as a response to variations in temperature and proximity to the coastline (Peti and Thibault, 2017;Peti et al, 2021), whereas the drop in size of this same taxon across the Toarcian Oceanic Anoxic Event has been interpreted as a response to a calcification crisis (Suan et al, 2010;Clémence et al, 2015;Faucher et al, 2022). Changes in the size of Early to Middle Jurassic coccolith Lotharingius species might reflect the opposition between stable environmental conditions favoring large specimens versus periods dominated by ecological stress favoring small specimens (Ferreira et al, 2017).…”

“…Morphological changes in calcareous nannofossils have been the subject of numerous studies across their evolutionary history in the Meso-Cenozoic. Perhaps due to better preserved records, Cenozoic biometric studies are abundant, while Mesozoic studies have focused mostly on specific intervals such as the Early to Middle Jurassic (Suchéras-Marx et al, 2010;Suan et al, 2010;Peti and Thibault, 2017;Peti et al, 2021;Menini et al, 2021;Faucher et al, 2022;López-Otálvaro et al, 2012;Ferreira et al, 2017) or Early to mid-Cretaceous (Bornemann and Mutterlose, 2006;Barbarin et al, 2012;Lübke and Mutterlose, 2016;Bottini and Faucher, 2020;Wulff et al, 2020). In comparison to the latter periods, and considering that the Santonian to Maastrichtian interval bears the highest diversity within the overall evolutionary history of calcareous nannoplankton (Bown et al 2004), this significant part of the Late Cretaceous has been the subject of relatively few biometric studies mostly focused on Arkhangelskiellaceae and the Eiffelithus lineages (Girgis, 1987;Faris 1995;Thibault et al, 2004;Linnert and Mutterlose, 2009;Shamrock and Watkins, 2009;Thibault, 2010;Linnert et al, 2014).…”