Benthic origin and earliest evolution of the first planktonic foraminifera after the Cretaceous/Palaeogene boundary mass extinction

Abstract

There are several hypotheses on the origin and evolution of the earliest Danian planktonic foraminifera. Most experts suggest that they descended from a few opportunist planktonic foraminifera species, mainly of the genera Guembelitria and Hedbergella, which are usually considered to be survivors of the Cretaceous/Paleogene (K/Pg) boundary mass extinction. Nevertheless, early Danian specimens of Guembelitria and Hedbergella remained morphologically well separated from the associated parvularugoglobigerinids (i.e. Parvularugoglobigerina and Palaeoglobigerina), the first trochospiral planktonic foraminifera appearing after the K/Pg boundary event. The most likely alternative is a benthic origin for the parvularugoglobigerinids, which would be consistent with molecular phylogenetic studies that have suggested several episodes of benthic-planktonic transitions in the evolutionary history of planktonic foraminifera. A review of material from the El Kef section and other Tunisian sections supports the previous hypothesis that the buliminid genus Caucasina is the ancestor of the first parvularugoglobigerinids (i.e. Parvularugoglobigerina longiapertura and Palaeoglobigerina alticonusa), on the basis of similarities in test and apertural morphologies and wall texture. The intermediate morphotypes between caucasinids and parvularugoglobigerinids, which appeared approximately 3–5 kyr after the K/Pg boundary, are assigned to Pseudocaucasina antecessor gen. nov. sp. nov.

Keywords:

• Parvularugoglobigerinids
• Caucasina
• evolution
• earliest Danian
• Tunisia

Acknowledgements

The authors would like to thank Carolina Náñez and Norberto Malumián for their helpful in preparing this manuscript. We thank two anonymous referees for their valuable revisions of the manuscript. This research was funded by the Spanish Ministerio de Economía y Competividad projects CGL2011-23077 and CGL2011-22912 (both cofinanced by the European Regional Development Fund), UZ2015-CIE-02 (funded by the Universidad de Zaragoza, Spain), and the Aragonian Departamento de Educación y Ciencia (DGA group E05) cofinanced by the European Social Fund (ESF). The authors would like to acknowledge the use of the Servicio General de Apoyo a la Investigación-SAI, Universidad de Zaragoza. The authors are grateful to Rupert Glasgow for improvement of the English text.

Disclosure statement

No potential conflict of interest was reported by the authors.