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Evolution of Amaurolithus: Amaurolithus delicatus marking the Messinian bottom

After a complete study of the sediment samples from Ocean Drilling Program (ODP) Sites 999 and 1237 in the Caribbean Sea and Eastern Pacific Ocean in order to monitor the evolution of ceratoliths. The First Occurrence of Amaurolithus delicatus marks the bottom of the Messinian Stage. The first ceratholith, A. primus, has two arms and a horseshoe shape with marked laths, and is stable and concave upwards having three blades (sinistral=blue, median=red, and dextral= green).

Early robust A. primus evolved into stylised forms and then to Amaurolithus delicatus (7.226 Ma), an almost plain horseshoe ceratolith with two arms. The left arm, usually the longer one, comes from the sinistral wing of A. primus and has a characteristic flattened omega section (Ω) without laths. There is a distribution overlap between A. primus and A. delicatus; the highest occurrence of the first one, at 6.282 Ma, is a newly proposed bioevent for the Messinian. After this, Amaurolithus does not have laths on its longer left arm and should be included in A. delicatus. 


Cite as: Lancis, C., Tent-Manclús, J.-E., Flores, J.-A., 2022. Origin and evolutionary trends of the Neogene genera Amaurolithus and Nicklithus (calcareous nannofossils). Mar. Micropaleontol. 175, 102156. https://doi.org/https://doi.org/10.1016/j.marmicro.2022.102156

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