Portail de Conférences / Conference Portal, JK2018

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Singular aragonitic foraminifers from the Berriasian of Bosnia
Sylvain Rigaud, Bruno Granier, Rossana Martini, Jean-Pierre Masse

Building: Muséum d'Histoire Naturelle de Genève
Room: Lobby /Hall/
Date: 2018-12-05 11:14 AM – 11:17 AM
Last modified: 2018-11-24


The use of aragonite in the construction of foraminiferal tests has been identified in both tubular (e.g., Involutinida, Tubulastellidae) and multichambered, benthic (e.g., Robertinina) and planktonic (Favusellidae), forms. All aragonitic foraminifers that have been described so far have shown a test made up of aragonite needles presenting a c-axis more or less perpendicular to the wall surface. We here illustrate for the first time three aragonitically-preserved fossil foraminifers, the tests of which are made of more or less randomly arranged bundles of aragonite needles.

These new multichambered foraminifers have been found in exceptionally well-preserved Berriasian levels of Bosnia. Due to their metastable nature, aragonitic tests are extremely rarely preserved in the fossil record. However, based on morphological and structural characteristics, we suspect that the newly described group may have a long but hidden evolutionary history. Morphologically comparable foraminifers have been found in a moderate state of preservation in the Jurassic and in the Triassic. The discovery of a new wall-type in Mesozoic aragonitic foraminifers questions the long-accepted monophyly of the order Robertinida.