Foraminiferal diversification during the late Paleozoic ice age

Abstract

A record of late Paleozoic foraminiferal diversity, origination and extinction frequencies, and provincialism at million-year temporal resolution and species-level taxonomic resolution has been achieved by analyzing composite standard databases. Foraminiferal species diversity increased throughout Mississippian and Pennsylvanian time leading up to its peak at the Pennsylvanian/Permian boundary. Foraminifers then experienced a steep decline in diversity during the Early Permian. Frequencies of origination and extinction broadly tracked changes in global diversity. From Late Mississippian time onward, patterns in total foraminiferal diversity were dominated by fusulinoideans. There is no clear relationship between rates of foraminiferal evolution and the alternating glacial and nonglacial intervals that characterized the late Paleozoic ice age. Rather, high rates of origination and extinction might reflect instability of neritic environments as a consequence of high-frequency, high-amplitude base-level fluctuations (cyclothemic deposition). Further, the advent of algal symbiosis in fusulinoideans was a physiologic innovation that promoted diversification as these symbiont-bearing taxa experimented with morphologic adaptations for partitioning the low-nutrient environments to which they were specialized. Growth to large size and delayed maturation in fusulinoideans might have been enabled by the late Paleozoic hyperoxic atmosphere and the widespread development of oligotrophic, carbonate platform and shelf environments. The late Paleozoic history of foraminiferal diversification was influenced also by closure of the Rheic Ocean beginning in Late Mississippian time. Foraminiferal associations on opposite sides of Pangea exhibited relatively high similarity prior to the closure, but then similarity decreased steadily after destruction of the subequatorial marine corridor. Arctic-Eurasian and North American associations were nearly isolated from one another throughout the main burst of fusulinoidean diversification, so that parallel lineages developed independently in the two regions, resulting in many instances of convergence.

Warm water benthic foraminifera document the Pennsylvanian–Permian warming and cooling events — The record from the Western Pangea tropical shelves

“…The first occurrence datum in both North American and Boreal shelves are well constrained and seem synchronous. This evolutionary event is also associated with the reduction of the fusulinid diversity in Podolskian in the eastern Pangaea and at the Atokan-Desmoinesian transition in the western Pangaea (Groves and Wang, 2009;Davydov et al, 2012) and increasing provincialism . The isochronicity of the occurrence of Wedekindellina in temperate climatic zones (Arctic-Urals and North American shelves) is interpreted here as evidence of a cooling event where cool-water assemblages in both North America shelves and northern Pangea shelves become more uniform then the warm water assemblages in these regions (Fig.…”

“…1) (Mamet, 1977;Davydov, 2008;Groves and Wang, 2009;) but no reasons for this situation have been offered. A possible reason proposed here is that North American shelves in tropical paleolatitude had predominantly temperate paleoclimates (Davydov, 2008(Davydov, , 2013.…”

“…The second potential cooling event corresponds with the major extinction event in the fusulinid evolution at the Moscovian-Kasimovian boundary (Kireeva, 1964;Reitlinger, 1969;Davydov, 1990;Davydov and Nilsson, 1999). This extinction is well expressed in Tethys (Leven and Davydov, 2001) and at the global scale (Groves and Wang, 2009;Davydov et al, 2012) and is associated with the unconformity in many regions in Pangaea (Davydov and Nilsson, 1999) and with the turnover of the early-middle Pennsylvanian fusulinellid fauna into the late Pennsylvanian-Permian schwagerinid fauna. In Boreal and North America provinces this event is marked by the occurrence Eowaeringella.…”

“…Another warming event during the late Gzhelian in the Tethyan and Boreal provinces is associated with the maximum peak in foraminiferal diversity and the global distribution of many fusulinid species (Groves and Wang, 2009;Davydov et al, 2012;Davydov, 2013;Davydov et al, 2013a;). In North American shelves it is marked by the occurrence of Occidentoschwagerina (=Advenella of Wilde, 2006), Likharevites (= "Alpinoschwagerina" of Wilde, 2006) and Schellwienia, which is thought here to include many North American species traditionally placed in Schwagerina or Pseudofusulina.…”

Stratigraphic Unconformities: Review of the Concept and Examples from the Middle-Upper Paleozoic

“…The latter controls biostratigraphic resolution to a significant extent by cosmopolitism vs. provincialism of marine faunas. High cosmopolitism is characteristic of greenhouse periods with circum-tropical seaway connections, whereas provincialism is favored by forcing of the Earth into icehouse mode and shutdowns of low-latitude seaway connections, as likely happened during Pennsylvanian-Permian assembly of Pangaea [36,37].…”