Articles | Volume 45, issue 1
https://doi.org/10.5194/jm-45-159-2026
https://doi.org/10.5194/jm-45-159-2026
Research article
 | 
09 Mar 2026
Research article |  | 09 Mar 2026

Early Eocene evolutionary trajectories within the Toweius genus: insights from a newly identified species in the equatorial Atlantic

Joseph D. Asanbe and Jorijntje Henderiks

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Cited articles

Agnini, C., Muttoni, G., Kent, D. V., and Rio, D.: Eocene biostratigraphy and magnetic stratigraphy from Possagno, Italy: The calcareous nannofossil response to climate variability, Earth Planet. Sc. Lett., 241, 815–830, https://doi.org/10.1016/j.epsl.2005.11.005, 2006. 
Agnini, C., Fornaciari, E., Rio, D., Tateo, F., Backman, J., and Giusberti, L.: Responses of calcareous nannofossil assemblages, mineralogy and geochemistry to the environmental perturbations across the Paleocene/Eocene boundary in the Venetian Pre-Alps, Mar. Micropaleontol., 63, 19–38, https://doi.org/10.1016/j.marmicro.2006.10.002, 2007. 
Alegret, L., Harper, D. T., Agnini, C., Newsam, C., Westerhold, T., Cramwinckel, M. J., Dallanave, E., Dickens, G. R., and Sutherland, R.: Biotic response to early Eocene warming events: Integrated record from Offshore Zealandia, North Tasman Sea, Paleoceanogr. Paleoclimatol., 36, https://doi.org/10.1029/2020PA004179, 2021. 
Asanbe, J. D. and Henderiks, J.: Major Shifts in Equatorial Atlantic and Pacific Calcareous Nannofossil Assemblages Across the Early Eocene Climatic Optimum (EECO; 53–49 Ma), Paleoceanogr. Paleoclimatol., 40, e2024PA005038, https://doi.org/10.1029/2024PA005038, 2025. 
Asanbe, J. and Henderiks, J.: Early Eocene evolutionary trajectories of within the Toweius genus: Insights from a newly identified species in the equatorial Atlantic – Coccolith biometric dataset, Zenodo [data set], https://doi.org/10.5281/zenodo.17201433, 2026. 
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Short summary
Toweius was among the most widespread and important calcareous nannoplankton groups in the oceans 53 million years ago, playing a key role in the evolutionary transition to another prominent group during the Cenozoic (Reticulofenestra). Using detailed biometric measurements with high-resolution imaging, we describe a distinctive, smaller morphotype of Toweius. Our results indicate that this form evolved gradually through speciation, shedding light on the complex evolutionary dynamics of Toweius.
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