The morphogroups of small agglutinated foraminifera from the Devonian carbonate complex of the Prague Synform, (Barrandian area, Czech Republic)

Abstract

Agglutinated foraminifera from the Lower and lower part of the Middle Devonian, predominantly limestones of the Prague Synform (Barrandian area), were classified into five morphogroups: morphogroup ED1 was divided to morphotype ED1a which is represented by foraminifera with straight tubular or branched tests. Irregularly coiled forms are separated to morphotype ED1b; ED2 morphogroup includes genera with planoconvex tests which can be divided into morphotype ED2a, characterized by planoconvex meandering tests, and morphotype ED2b with subglobular tests; the ED3 morphogroup contains genera with discoidal (flattened) planispirally coiled forms; the ED4 group consists of globular forms, whilst simple globular forms without marked tubular projections are representatives of morphotype ED4a, and globular morphotypes ED4b with apertures on marked neck-like projections; and morphogroup ED5 is represented by very rare multilocular morphotypes. The absence of the deep infaunal morphogroups is characteristic. The morphogroup distribution has been strongly affected by oxygen concentration, the energy of the environment, nutrient availability and post-mortem processes. Intervals with diversified and abundant foraminiferal assemblages can be correlated with positive δ13C excursions and also with the deposition of nodular limestones. The Devonian assemblages from the Prague Synform were compared with isochronous assemblages from other regions. Though the taxonomical composition of the Early Devonian assemblages from these areas are rather different, the morphogroup composition is highly comparable, and globally indicates similar life and feeding strategies of the Early Devonian foraminifera.