Articles | Volume 45, issue 1
https://doi.org/10.5194/jm-45-159-2026
© Author(s) 2026. This work is distributed under
the Creative Commons Attribution 4.0 License.
the Creative Commons Attribution 4.0 License.
https://doi.org/10.5194/jm-45-159-2026
© Author(s) 2026. This work is distributed under
the Creative Commons Attribution 4.0 License.
the Creative Commons Attribution 4.0 License.
Research article
| 
09 Mar 2026
Research article |
| 09 Mar 2026
| 09 Mar 2026
Early Eocene evolutionary trajectories within the Toweius genus: insights from a newly identified species in the equatorial Atlantic
Department of Earth Sciences, Uppsala University, Uppsala, Sweden
Jorijntje Henderiks
Department of Earth Sciences, Uppsala University, Uppsala, Sweden
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Marine sediments help us investigate the end of a long period of high ocean productivity that occurred 9 to 3 million years ago. By comparing fossil assemblages of calcifying algae from the Indian and South Atlantic oceans, we found that the dominant, fast-growing species and their ecological prominence determined how and when this period ended in each region, showing that phytoplankton species’ dynamics control large changes in paleoproductivity and carbonate deposition across ocean basins.
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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.
Bach, L. T., Riebesell, U., Gutowska, M. A., Federwisch, L., and Schulz, K. G.: A unifying concept of coccolithophore sensitivity to changing carbonate chemistry embedded in an ecological framework, Prog. Oceanogr., 135, 125–138, https://doi.org/10.1016/j.pocean.2015.04.012, 2015.
Beaufort, L.: Weight estimates of coccoliths using the optical properties (birefringence) of calcite, Micropaleontology, 51, 289–297, https://doi.org/10.2113/gsmicropal.51.4.289, 2005.
Beaufort, L., Probert, I., de Garidel-Thoron, T., Bendif, E. M., Ruiz-Pino, D., Metzl, N., Goyet, C., Buchet, N., Coupel, P., Grelaud, M., Rost, B., Rickaby, R. E. M., and de Vargas, C.: Sensitivity of coccolithophores to carbonate chemistry and ocean acidification, Nature, 476, 80–83, https://doi.org/10.1038/nature10295, 2011.
Beaufort, L., Barbarin, N., and Gally, Y.: Optical measurements to determine the thickness of calcite crystals and the mass of thin carbonate particles such as coccoliths, Nat. Protoc., 9, 633–642, https://doi.org/10.1038/nprot.2014.028, 2014.
Beaufort, L., Gally, Y., Suchéras-Marx, B., Ferrand, P., and Duboisset, J.: Technical note: A universal method for measuring the thickness of microscopic calcite crystals, based on bidirectional circular polarization, Biogeosciences, 18, 775–785, https://doi.org/10.5194/bg-18-775-2021, 2021.
Bendif, E. M., Nevado, B., Wong, E. L. Y., Hagino, K., Probert, I., Young, J. R., Rickaby, R. E. M., and Filatov, D. A.: Repeated species radiations in the recent evolution of the key marine phytoplankton lineage Gephyrocapsa, Nat. Commun., 10, 4234, https://doi.org/10.1038/s41467-019-12169-7, 2019.
Bolton, C. T. and Stoll, H. M.: Late Miocene threshold response of marine algae to carbon dioxide limitation, Nature, 500, 558–562, https://doi.org/10.1038/nature12448, 2013.
Bordiga, M., Bartol, M., and Henderiks, J.: Absolute nannofossil abundance estimates: Quantifying the pros and cons of different techniques, Revue de Micropaléontologie, 58, 155–165, https://doi.org/10.1016/j.revmic.2015.05.002, 2015.
Bown, P. and Pearson, P.: Calcareous plankton evolution and the Paleocene/Eocene thermal maximum event: New evidence from Tanzania, Mar. Micropaleontol., 71, 60–70, https://doi.org/10.1016/j.marmicro.2009.01.005, 2009.
Bown, P. R.: Calcareous nannofossils from the Paleocene/Eocene Thermal Maximum interval of southern Tanzania (TDP Site 14), International Nannoplankton Association, 31, 11–38, 2010.
Bown, P. R., Lees, J. A., and Young, J. R.: Calcareous nannoplankton evolution and diversity through time, in: Coccolithophores, edited by: Thierstein, H. R. and Young, J. R., Springer Berlin Heidelberg, Berlin, Heidelberg, 481–508, https://doi.org/10.1007/978-3-662-06278-4_18, 2004.
Bown, P. R., Jones, T. D., Lees, J. A., Randell, R. D., Mizzi, J. A., Pearson, P. N., Coxall, H. K., Young, J. R., Nicholas, C. J., Karega, A., Singano, J., and Wade, B. S.: A Paleogene calcareous microfossil Konservat-Lagerstatte from the Kilwa Group of coastal Tanzania, Geol. Soc. Am. Bull., 120, 3–12, https://doi.org/10.1130/B26261.1, 2008.
Bown, P. R., Kim, H., and Gibbs, S. J.: Danian calcareous nannofossil evolution and taxonomy with focus on sites from the North Atlantic Ocean (IODP Expedition 342, Sites U1403 and U1407), J. Nannoplankton Res., 41, 110–157, https://doi.org/10.58998/jnr3943, 2023.
Bralower, T. J.: Evidence of surface water oligotrophy during the Paleocene-Eocene thermal maximum: Nannofossil assemblage data from Ocean Drilling Program Site 690, Maud Rise, Weddell Sea, Paleoceanography, 17, https://doi.org/10.1029/2001PA000662, 2002.
Bralower, T. J. and Mutterlose, J.: Calcareous nannofossil biostratigraphy of Site 865, Allison Guyot, central Pacific Ocean: A tropical Paleogene reference section, in: Proceedings of the Ocean Drilling Program, Scientific Results, vol. 143, Ocean Drilling Program, College Station, https://doi.org/10.2973/odp.proc.sr.143.204.1995, 1995.
Cappelli, C., Bown, P. R., Westerhold, T., Bohaty, S. M., Riu, M., Lobba, V., Yamamoto, Y., and Agnini, C.: The early to middle Eocene transition: An integrated calcareous nannofossil and stable isotope record from the Northwest Atlantic Ocean (Integrated Ocean Drilling Program Site U1410), Paleoceanogr. Paleoclimatol.,, 34, 1913–1930, https://doi.org/10.1029/2019PA003686, 2019.
Cubillos, J. C., Henderiks, J., Beaufort, L., Howard, W. R., and Hallegraeff, G. M.: Reconstructing calcification in ancient coccolithophores: Individual coccolith weight and morphology of Coccolithus pelagicus (sensu lato), Mar. Micropaleontol., 92–93, 29–39, https://doi.org/10.1016/j.marmicro.2012.04.005, 2012.
Dunkley Jones, T., Bown, P. R., Pearson, P. N., Wade, B. S., Coxall, H. K., and Lear, C. H.: Major shifts in calcareous phytoplankton assemblages through the Eocene-Oligocene transition of Tanzania and their implications for low-latitude primary production, Paleoceanography, 23, 2008PA001640, https://doi.org/10.1029/2008PA001640, 2008.
Erbacher, J., Mosher, D. C., Malone, M. J., Sexton, P., and Wilson, P. A. (Eds.): Proceedings of the Ocean Drilling Program, 207 Initial Reports, Ocean Drilling Program, https://doi.org/10.2973/odp.proc.ir.207.2004, 2004.
Faucher, G., Riebesell, U., and Bach, L. T.: Can morphological features of coccolithophores serve as a reliable proxy to reconstruct environmental conditions of the past?, Clim. Past, 16, 1007–1025, https://doi.org/10.5194/cp-16-1007-2020, 2020.
Gerecht, A. C., Šupraha, L., Edvardsen, B., Probert, I., and Henderiks, J.: High temperature decreases the PIC / POC ratio and increases phosphorus requirements in Coccolithus pelagicus (Haptophyta), Biogeosciences, 11, 3531–3545, https://doi.org/10.5194/bg-11-3531-2014, 2014.
Gibbs, S. J., Bown, P. R., Sessa, J. A., Bralower, T. J., and Wilson, P. A.: Nannoplankton extinction and origination across the Paleocene-Eocene Thermal Maximum, Science, 314, 1770–1773, https://doi.org/10.1126/science.1133902, 2006.
Gibbs, S. J., Sheward, R. M., Bown, P. R., Poulton, A. J., and Alvarez, S. A.: Warm plankton soup and red herrings: calcareous nannoplankton cellular communities and the Palaeocene–Eocene Thermal Maximum, Phil. Trans. R. Soc. A., 376, 20170075, https://doi.org/10.1098/rsta.2017.0075, 2018.
Hagino, K., Okada, H., and Matsuoka, H.: Spatial dynamics of coccolithophore assemblages in the Equatorial Western-Central Pacific Ocean, Mar. Micropaleontol., 39, 53–72, https://doi.org/10.1016/S0377-8398(00)00014-1, 2000.
Haq, B. U. and Lohmann, G. P.: Early Cenozoic calcareous nannoplankton biogeography of the Atlantic Ocean, Mar. Micropaleontol., 1, 119–194, https://doi.org/10.1016/0377-8398(76)90008-6, 1976.
Hay, W. W. and Mohler, H. P.: Calcareous nannoplankton from early Tertiary rocks at Pont Labau, France, and Paleocene-early Eocene correlations, Journal of Paleontology, 41, 1505–1541, 1967.
Henderiks, J.: Coccolithophore size rules – Reconstructing ancient cell geometry and cellular calcite quota from fossil coccoliths, Mar. Micropaleontol., 67, 143–154, https://doi.org/10.1016/j.marmicro.2008.01.005, 2008.
Henderiks, J., Sturm, D., Šupraha, L., and Langer, G.: Evolutionary Rates in the Haptophyta: Exploring Molecular and Phenotypic Diversity, J. Mar. Sci. Eng., 10, 798, https://doi.org/10.3390/jmse10060798, 2022.
Hollis, C. J., Handley, L., Crouch, E. M., Morgans, H. E. G., Baker, J. A., Creech, J., Collins, K. S., Gibbs, S. J., Huber, M., Schouten, S., Zachos, J. C., and Pancost, R. D.: Tropical sea temperatures in the high-latitude South Pacific during the Eocene, Geology, 37, 99–102, https://doi.org/10.1130/G25200A.1, 2009.
Hollis, C. J., Dunkley Jones, T., Anagnostou, E., Bijl, P. K., Cramwinckel, M. J., Cui, Y., Dickens, G. R., Edgar, K. M., Eley, Y., Evans, D., Foster, G. L., Frieling, J., Inglis, G. N., Kennedy, E. M., Kozdon, R., Lauretano, V., Lear, C. H., Littler, K., Lourens, L., Meckler, A. N., Naafs, B. D. A., Pälike, H., Pancost, R. D., Pearson, P. N., Röhl, U., Royer, D. L., Salzmann, U., Schubert, B. A., Seebeck, H., Sluijs, A., Speijer, R. P., Stassen, P., Tierney, J., Tripati, A., Wade, B., Westerhold, T., Witkowski, C., Zachos, J. C., Zhang, Y. G., Huber, M., and Lunt, D. J.: The DeepMIP contribution to PMIP4: methodologies for selection, compilation and analysis of latest Paleocene and early Eocene climate proxy data, incorporating version 0.1 of the DeepMIP database, Geosci. Model Dev., 12, 3149–3206, https://doi.org/10.5194/gmd-12-3149-2019, 2019.
Kahn, A. and Aubry, M.-P.: Provincialism associated with the Paleocene/Eocene thermal maximum: temporal constraint, Mar. Micropaleontol., 52, 117–131, https://doi.org/10.1016/j.marmicro.2004.04.003, 2004.
Kelly, D. C., Bralower, T. J., Zachos, J. C., Silva, I. P., and Thomas, E.: Rapid diversification of planktonic foraminifera in the tropical Pacific (ODP Site 865) during the late Paleocene thermal maximum, Geol., 24, 423, https://doi.org/10.1130/0091-7613(1996)024<0423:RDOPFI>2.3.CO;2, 1996.
Langer, G., Probert, I., Nehrke, G., and Ziveri, P.: The morphological response of Emiliania huxleyi to seawater carbonate chemistry changes: an inter-strain comparison, J. Nannoplankton Res., 32, 29–36, https://doi.org/10.58998/jnr2159, 2011.
Ma, R., Aubry, M.-P., Bord, D., Jin, X., and Liu, C.: Inferred nutrient forcing on the late middle Eocene to early Oligocene (∼ 40–31 Ma) evolution of the coccolithophore Reticulofenestra (order Isochrysidales), Paleobiology, 50, 29–42, https://doi.org/10.1017/pab.2023.20, 2024.
Martini, E.: Standard Tertiary and Quaternary calcareous nannoplankton zonation, in Proceedings of the Second Planktonic Conference Roma 1970, Edizioni Technoscienza, Rome, 2, 739–785, 1971.
Mather, B. R., Müller, R. D., Zahirovic, S., Cannon, J., Chin, M., Ilano, L., Wright, N. M., Alfonso, C., Williams, S., Tetley, M., and Merdith, A.: Deep time spatio-temporal data analysis using pyGPlates with Plate Tectonic Tools and GPlately, Geosci. Data J., 11, 3–10, https://doi.org/10.1002/gdj3.185, 2023.
McClelland, H. L. O., Barbarin, N., Beaufort, L., Hermoso, M., Ferretti, P., Greaves, M., and Rickaby, R. E. M.: Calcification response of a key phytoplankton family to millennial-scale environmental change, Sci. Rep., 6, 34263, https://doi.org/10.1038/srep34263, 2016.
Meier, K. J. S., Berger, C., and Kinkel, H.: Increasing coccolith calcification during CO2 rise of the penultimate deglaciation (Termination II), Mar. Micropaleontol., 112, 1–12, https://doi.org/10.1016/j.marmicro.2014.07.001, 2014a.
Meier, K. J. S., Beaufort, L., Heussner, S., and Ziveri, P.: The role of ocean acidification in Emiliania huxleyi coccolith thinning in the Mediterranean Sea, Biogeosciences, 11, 2857–2869, https://doi.org/10.5194/bg-11-2857-2014, 2014b.
Müller, R. D., Cannon, J., Williams, S., and Dutkiewicz, A.: PyBacktrack 1.0: A Tool for Reconstructing Paleobathymetry on Oceanic and Continental Crust, Geochem. Geophy. Geosy., 19, 1898–1909, https://doi.org/10.1029/2017GC007313, 2018.
Müller, R. D., Zahirovic, S., Williams, S. E., Cannon, J., Seton, M., Bower, D. J., Tetley, M. G., Heine, C., Le Breton, E., Liu, S., Russell, S. H. J., Yang, T., Leonard, J., and Gurnis, M.: A global plate model including lithospheric deformation along major rifts and orogens since the Triassic, Tectonics, 38, 1884–1907, https://doi.org/10.1029/2018TC005462, 2019.
Mutterlose, J., Linnert, C., and Norris, R.: Calcareous nannofossils from the Paleocene–Eocene Thermal Maximum of the equatorial Atlantic (ODP Site 1260B): Evidence for tropical warming, Mar. Micropaleontol., 65, 13–31, https://doi.org/10.1016/j.marmicro.2007.05.004, 2007.
Pearson, P. N., McMillan, I. K., Wade, B. S., Jones, T. D., Coxall, H. K., Bown, P. R., and Lear, C. H.: Extinction and environmental change across the Eocene-Oligocene boundary in Tanzania, Geol., 36, 179, https://doi.org/10.1130/G24308A.1, 2008.
Raffi, I. and De Bernardi, B.: Response of calcareous nannofossils to the Paleocene–Eocene Thermal Maximum: Observations on composition, preservation and calcification in sediments from ODP Site 1263 (Walvis Ridge – SW Atlantic), Mar. Micropaleontol., 69, 119–138, https://doi.org/10.1016/j.marmicro.2008.07.002, 2008.
Raffi, I., Backman, J., and Pälike, H.: Changes in calcareous nannofossil assemblages across the Paleocene/Eocene transition from the paleo-equatorial Pacific Ocean, Palaeogeography, Palaeoclimatology, Palaeoecology, 226, 93–126, https://doi.org/10.1016/j.palaeo.2005.05.006, 2005.
Romein, A. J. T.: Evolutionary lineages in early Paleogene calcareous nannoplankton, Utrecht Micropaleontological Bulletins, 22, 1–230, 1979.
Roth, P. H.: Cretaceous nannoplankton biostratigraphy and oceanography of the Northwestern Atlantic Ocean, in: Initial reports of the Deep Sea Drilling Project; Volume XLIV covering Leg 44 of the cruises of the drilling vessel Glomar Challenger, Norfolk, 44, 731–759, https://doi.org/10.2973/dsdp.proc.44.134.1978, 1978.
Roth, P. H. and Thierstein, H. R.: Calcareous nannoplankton: Leg 14 of the Deep Sea Drilling Project, Init. Repts. DSDP, 14, 421–485, https://doi.org/10.2973/dsdp.proc.14.114.1972, 1972.
Schneider, L. J., Bralower, T. J., and Kump, L. R.: Response of nannoplankton to early Eocene ocean destratification, Palaeogeography, Palaeoclimatology, Palaeoecology, 310, 152–162, https://doi.org/10.1016/j.palaeo.2011.06.018, 2011.
Self-Trail, J. M., Powars, D. S., Watkins, D. K., and Wandless, G. A.: Calcareous nannofossil assemblage changes across the Paleocene–Eocene Thermal Maximum: Evidence from a shelf setting, Mar. Micropaleontol., 92–93, 61–80, https://doi.org/10.1016/j.marmicro.2012.05.003, 2012.
Shamrock, J. L. and Watkins, D. K.: Eocene calcareous nannofossil biostratigraphy and community structure from Exmouth Plateau, Eastern Indian Ocean (ODP Site 762), Stratigraphy, 9, https://doi.org/10.29041/strat.09.1.01, 2012.
Shepherd, C. L., Kulhanek, D. K., Hollis, C. J., Morgans, H. E. G., Strong, C. P., Pascher, K. M., and Zachos, J. C.: Calcareous nannoplankton response to early Eocene warmth, Southwest Pacific Ocean, Mar. Micropaleontol., 165, 101992, https://doi.org/10.1016/j.marmicro.2021.101992, 2021.
Sullivan, F. R.: Lower Tertiary Nannoplankton from the California Coast Ranges, University of California Press, ISBN 9780598201416, 1965.
Šupraha, L. and Henderiks, J.: A 15-million-year-long record of phenotypic evolution in the heavily calcified coccolithophore Helicosphaera and its biogeochemical implications, Biogeosciences, 17, 2955–2969, https://doi.org/10.5194/bg-17-2955-2020, 2020.
Triantaphyllou, M., Dimiza, M., Krasakopoulou, E., Malinverno, E., Lianou, V., and Souvermezoglou, E.: Seasonal variation in Emiliania huxleyi coccolith morphology and calcification in the Aegean Sea (Eastern Mediterranean), Geobios, 43, 99–110, https://doi.org/10.1016/j.geobios.2009.09.002, 2010.
Wei, W. and Wise, S. W.: Biogeographic gradients of middle Eocene-Oligocene calcareous nannoplankton in the South Atlantic Ocean, Palaeogeography, Palaeoclimatology, Palaeoecology, 79, 29–61, https://doi.org/10.1016/0031-0182(90)90104-F, 1990.
Westerhold, T. and Röhl, U.: High resolution cyclostratigraphy of the early Eocene – new insights into the origin of the Cenozoic cooling trend, Clim. Past, 5, 309–327, https://doi.org/10.5194/cp-5-309-2009, 2009.
Westerhold, T., Röhl, U., Frederichs, T., Agnini, C., Raffi, I., Zachos, J. C., and Wilkens, R. H.: Astronomical calibration of the Ypresian timescale: implications for seafloor spreading rates and the chaotic behavior of the solar system?, Clim. Past, 13, 1129–1152, https://doi.org/10.5194/cp-13-1129-2017, 2017.
Westerhold, T., Röhl, U., Donner, B., and Zachos, J. C.: Global extent of early Eocene hyperthermal events: A new Pacific benthic foraminiferal isotope record from Shatsky Rise (ODP Site 1209), Paleoceanogr. Paleoclimatol., 33, 626–642, https://doi.org/10.1029/2017PA003306, 2018.
Westerhold, T., Marwan, N., Drury, A. J., Liebrand, D., Agnini, C., Anagnostou, E., Barnet, J. S. K., Bohaty, S. M., De Vleeschouwer, D., Florindo, F., Frederichs, T., Hodell, D. A., Holbourn, A. E., Kroon, D., Lauretano, V., Littler, K., Lourens, L. J., Lyle, M., Pälike, H., Röhl, U., Tian, J., Wilkens, R. H., Wilson, P. A., and Zachos, J. C.: An astronomically dated record of Earth's climate and its predictability over the last 66 million years, Science, 369, 1383–1387, https://doi.org/10.1126/science.aba6853, 2020.
Young, J. R.: Possible functional interpretation of coccolith morphology, Geologische Bundesanstalt, 305–313, ISBN 3-900312-54-0, 1987.
Young, J. R.: Size variation of Neogene Reticulofenestra coccoliths from Indian Ocean DSDP Cores, J. Micropalaeontol., 9, 71–85, https://doi.org/10.1144/jm.9.1.71, 1990.
Young, J. R.: The description and analysis of coccolith structure, in: Proceedings of the 4th INA Conference, edited by: Hamrsmid, B. and Young, J. R., Prague, Knihovnicka ZPN, 14a, 35–71, 1992.
Young, J. R., Geisen, M., Cros, L., Kleijne, A., Probert, I., and Ostergaard, J. B.: A guide to extant coccolithophore taxonomy, J. Nannoplankton Res., S1, 1–132, https://doi.org/10.58998/jnr2297, 2003.
Young, J. R., Geisen, M., and Probert, I.: A review of selected aspects of coccolithophore biology with implications for paleobiodiversity estimation, Micropaleontology, 51, 267–288, https://doi.org/10.2113/gsmicropal.51.4.267, 2005.
Zachos, J., Pagani, M., Sloan, L., Thomas, E., and Billups, K.: Trends, Rhythms, and Aberrations in Global Climate 65 Ma to Present, Science, 292, 686–693, https://doi.org/10.1126/science.1059412, 2001.
Zachos, J. C., Dickens, G. R., and Zeebe, R. E.: An early Cenozoic perspective on greenhouse warming and carbon-cycle dynamics, Nature, 451, 279–283, https://doi.org/10.1038/nature06588, 2008.
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.
Toweius was among the most widespread and important calcareous nannoplankton groups in the...
