Extinction of nanicellid foraminifera during the Frasnian–Famennian biotic crisis: some far-reaching evolutionary consequences

This study evaluates the severity of the poorly known and mostly underestimated foraminiferal extinction during the Frasnian–Famennian biotic crisis and its evolutionary aftermath. During this global event, worldwide, truly plurilocular planispiral (Nanicellidae) and uniseriate, palmate (Semitextulariidae) foraminifera associated with metazoan reefs died out entirely. Highly advanced test morphology such as that of nanicellids did not reappear in the earth's history until the Late Triassic. Moreover, morphotype comparable to that of the Devonian bilaterally flattened and palmate semitextularids appeared again until the Middle Jurassic (Frondicularia, Lagenida). In terms of the degree of test septation and chamber arrangement as well as general test shape, these foraminifera were ‘very far ahead of their time’. In consequence, foraminifera suffered a significant collapse during the F-F biodiversity crisis, leading to an amazingly long evolutionary time lag in the case of plurilocular foraminifera lasting at least 150 million years.