TY - JOUR

T1 - Morphometric changes in two Late Cretaceous calcareous nannofossil lineages support diversification fueled by long-term cooling

AU - Razmjooei, Mohammad Javad

AU - Thibault, Nicolas Rudolph

PY - 2022

Y1 - 2022

N2 - Morphometric changes have been investigated in the two groups of calcareous nannofossils, Cribrosphaerella ehrenbergii and Microrhabdulus undosus across the Campanian to Maastrichtian of the Zagros Basin of Iran. Results reveal a common episode of size increase at c. 76 Ma, with a sudden increase in the size of C. ehrenbergii and with the emergence of a newly defined, larger species Microrhabdulus zagrosensis n.sp. An even larger species emerges at c. 69 Ma within the Microrhabdulus lineage, Microrhabdulus sinuosus n.sp. The timing of these size changes and origination events matches global changes in nannoplankton diversity and/or in diversity of other planktonic organisms and marine invertebrates. Comparison with long-term global climate change supports that these two distinct episodes of morphological change coincide respectively with the late Campanian carbon isotope event and acceleration of cooling and with climatic instability across the mid-Maastrichtian event.

AB - Morphometric changes have been investigated in the two groups of calcareous nannofossils, Cribrosphaerella ehrenbergii and Microrhabdulus undosus across the Campanian to Maastrichtian of the Zagros Basin of Iran. Results reveal a common episode of size increase at c. 76 Ma, with a sudden increase in the size of C. ehrenbergii and with the emergence of a newly defined, larger species Microrhabdulus zagrosensis n.sp. An even larger species emerges at c. 69 Ma within the Microrhabdulus lineage, Microrhabdulus sinuosus n.sp. The timing of these size changes and origination events matches global changes in nannoplankton diversity and/or in diversity of other planktonic organisms and marine invertebrates. Comparison with long-term global climate change supports that these two distinct episodes of morphological change coincide respectively with the late Campanian carbon isotope event and acceleration of cooling and with climatic instability across the mid-Maastrichtian event.

U2 - 10.24072/pcjournal.183

DO - 10.24072/pcjournal.183

M3 - Journal article

VL - 2

JO - Peer Community Journal

JF - Peer Community Journal

SN - 2804-3871

M1 - e64

ER -