The Paleozoic record of Thaumatoporella PIA, 1927?

Abstract

From Palaeozoic (mainly Devonian) shallow-water carbonates, spherical to irregular shaped microfossils with thin, apparently homogeneous or perforate micritic walls are widely reported. They are classically referred either to unilocular parathuramminid foraminifera, algae incertae sedis or calcispheres (e.g., Bisphaera, Cribrosphaeroides, Uslonia, Vermiporella myna, Irregularina). Due to their morphology and microstructural features, they are here reassessed more accurately as belonging to Thaumatoporella PIA, a widespread Mesozoic-Early Cenozoic taxon of incertae sedis showing a remarkably high morphological variability. In analogy to Mesozoic thaumatoporellaceans, Bisphaera malevkensis BIRINA is interpreted as the cyst (= resting) stage of forms ascribed to different genera, i.e., Cribrosphaeroides, Uslonia and Vermiporella (here: Vermiporella myna WRAY). This new interpretation leads to taxonomic reassessment as Thaumatoporella malevkensis (BIRINA) nov. comb. As a consequence of our interpretation, the rather long Mesozoic to Early Cenozoic (Ladinian to Early Ypresian) record of thaumatoporellaceans is supposed to be significantly larger than formerly assumed, showing four periods of increased abundance in the Middle/Late Devonian, Late Permian (?), Early/Middle Jurassic and Late Cretaceous time windows.