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Estonian Journal of Earth Sciences
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Possible metazoan egg fossils from the Darriwilian (Middle Ordovician) of Baltoscandia; pp. 240–252
PDF | 10.3176/earth.2021.16

Olle Hints, Jaak Nõlvak, Yan Liang

The Baltoscandian lower Palaeozoic succession is well known for the abundance, diversity and excellent preservation of various groups of microfossils, such as acritarchs, chitinozoans, scolecodonts and conodonts. This paper describes a new enigmatic Middle Ordovician organic-walled microfossil Vikisphaera kundanagen. et sp. nov., characterized by a dark brown to black hollow spherical shell, 90–200 μm in diameter, with an equatorial groove and lack of openings. The specimens of Vikisphaera have been collected from several localities across Baltoscandia including Estonia, Sweden, Latvia and northwestern Russia, and their stratigraphic range is restricted to the Kunda Regional Stage, lower Darriwilian. The wide geographical distribution and short temporal range of Vikisphaera imply its biostratigraphic utility. The shape and characteristics of the shell wall of Vikisphaera are different from those of prasinophytes and other organic-walled microfossils common in lower Palaeozoic rocks. The new microfossil resembles egg shells of some invertebrates, such as arthropods, suggesting that it could represent egg capsules of a group of marine metazoans, possibly soft-bodied creatures with low fossilization potential. However, before the metazoan origin of Vikisphaera is confirmed, it can be considered as an acritarch – an organic-walled microfossil of unknown affinity.


Achab, A. & Paris, F. 2007. The Ordovician chitinozoan biodiversification and its leading factors. Palaeogeography, Palaeoclimatology, Palaeoecology245, 5–19.

Ainsaar, L., Kaljo, D., Martma, T., Meidla, T., Männik, P., Nõlvak, J. & Tinn, O. 2010. Middle and Upper Ordovician carbon isotope chemostratigraphy in Baltoscandia: A cor­relation standard and clues to environmental history. Palaeogeography, Palaeoclimatology, Palaeoecology294, 189–201.

Bengtson, S. & Zhao, Y. 1997. Fossilized metazoan embryos from the earliest Cambrian. Science277, 1645–1648.

Bergström, S. M., Chen, X., Gutiérrez-Marco, J. C. & Dronov, A. 2009. The new chronostratigraphic classification of the Ordovician System and its relations to major regional series and stages and to δ13C chemostratigraphy. Lethaia42, 97–107.

Bergström, S. M., Calner, M., Lehnert, O. & Noor, A. 2011. A new upper Middle Ordovician–Lower Silurian drillcore standard succession from Borenshult in Östergötland, southern Sweden: 1. Stratigraphical review with regional comparisons. GFF133, 149–171.

Bergström, S. M., Ahlberg, P., Maletz, J., Lundberg, F. & Joachimski, M. M. 2018. Darriwilian (Middle Ordovician) chemostratigraphy linked to graptolite, conodont and trilobite biostratigraphy in the Fågelsång-3 drill core, Scania, Sweden. GFF140, 229–240.

Cocks, L. R. M. & Torsvik, T. H. 2005. Baltica from the late Precambrian to mid-Palaeozoic times: The gain and loss of a terrane’s identity. Earth-Science Reviews72, 39–66.

Cocks, L. R. M. & Torsvik, T. H. 2020. Ordovician palaeo­geography and climate change. Gondwana Research, S1342937X20302756.

Cohen, P. A., Knoll, A. H. & Kodner, R. B. 2009. Large spinose microfossils in Ediacaran rocks as resting stages of early animals. Proceedings of the National Academy of Sciences106, 6519–6524.

Eisenack, A. 1931. Neue Mikrofossilien des baltischen Silurs. I. Paläontologische Zeitschrift13, 74–118.

Eisenack, A. 1932. Neue Mikrofossilien des baltischen Silurs. II. Paläontologische Zeitschrift14, 257–277.

Eisenack, A. 1934. Neue Mikrofossilien des baltischen Silurs. III. und neue Mikrofossilien des böhmischen Silurs. I. Paläontologische Zeitschrift16, 52–76.

Eisenack, A. 1937. Was ist MelanostrophusZeitschrift für Geschiebeforschung und Flachlandsgeologie13, 100–104.

Eisenack, A. 1963. Über einige Arten der Gattung Tasmanites Newton 1875. Grana Palynologica4, 203–216.

Eiserhardt, K.-H. 1984. Carinatosphaeridium n. g. (Acritarcha) aus einem Öjlemyr-Flintgeschiebe Gotlands (ob. Ordoviz.). Neues Jahrbuch für Geologie und Paläontologie  Monatshefte Jg.9, 521–528.

Eiserhardt, K.-H. 1992. Die Acritarchen des Öjlemyrflintes. Palaeontographica Abt. B226, 1–132.

Eriksson, M. E., Lindskog, A., Servais, T., Hints, O. & Tonarová, P. 2016. Darriwilian (Middle Ordovician) worms of southern Sweden. GFF138, 502–509.

Evitt, W. R. 1963. A discussion and proposals concerning fossil dinoflagellates, hystrichospheres, and acritarchs, I. Proceedings of the National Academy of Sciences49, 158–164.

Finkel, Z. V., Sebbo, J., Feist-Burkhardt, S., Irwin, A. J., Katz, M. E., Schofield, O. M. E., Young, J. R. & Falkowski, P. G. 2007. A universal driver of macroevolutionary change in the size of marine phytoplankton over the Cenozoic. Proceedings of the National Academy of Sciences104, 20416–20420.

Goldman, D., Sadler, P. M. & Leslie, S. A. 2020. Chapter 20. The Ordovician Period. In Geologic Time Scale 2020. Volume 2 (Gradstein, F. M., Ogg, J. G., Schmitz, M. D. & Ogg, G. M., eds), pp. 631–694. Elsevier.

Grahn, Y. & Nõlvak, J. 2010. Swedish Ordovician Chitinozoa and biostratigraphy: a review and new data. Palaeonto­graphica Abt. B283, 1–71.

Grahn, Y. & Paris, F. 2011. Emergence, biodiversification and extinction of the chitinozoan group. Geological Magazine148, 226–236.

Guy-Ohlson, D. 1996. Chapter 7B. Prasinophycean algae. In Palynology: Principles and Applications (Jansonius, J. & McGregor, D. C., eds), pp. 181–189. American Association of Stratigraphic Palynologists Foundation.

Hagen-Peter, G., Wang, Y., Hints, O., Prave, A. R. & Lepland, A. 2021. Late diagenetic evolution of Ordovician limestones in the Baltoscandian basin revealed through trace-element mapping and in situ U–Pb dating of calcite. Chemical Geology585, 120563.

Hairston, N. G., Van Brunt, R. A., Kearns, C. M. & Engstrom, D. R. 1995. Age and survivorship of diapause eggs in a sediment egg bank. Ecology76, 1706–1711.

Harper, D. A. T. 2006. The Ordovician biodiversification: Setting an agenda for marine life. Palaeogeography, Palaeo­climatology, Palaeoecology232, 148–166.

Harper, D. A. T., Cascales-Miñana, B. & Servais, T. 2020. Early Palaeozoic diversifications and extinctions in the marine biosphere: a continuum of change. Geological Magazine157, 5–21.

Harvey, T. H. P. & Pedder, B. E. 2013. Copepod mandible palynomorphs from the Nolichucky Shale (Cambrian, Tennessee): implications for the taphonomy and recovery of small carbonaceous fossils. PALAIOS28, 278–284.

Hegna, T. A. & Lazo-Wasem, E. A. 2010. Branchinecta brushi n. sp. (Branchiopoda: Anostraca: Branchinectidae) from a Volcanic Crater in Northern Chile (Antofagasta Province): A New Altitude Record for Crustaceans. Journal of Crustacean Biology30, 445–464.

Hegna, T. A., Martin, M. J. & Darroch, S. A. F. 2017. Pyritized in situ trilobite eggs from the Ordovician of New York (Lorraine Group): Implications for trilobite reproductive biology. Geology45, 199–202.

Heuse, T., Lehnert, O. & Kraft, P. 1996. Organic-walled micro­fossils Incertae Sedis from the Ordovician of the Argentine Precordillera and Bohemia. Acta Universitatis Carolinae Geologica40, 425–439.

Hints, O. 2000. Ordovician eunicid polychaetes of Estonia and surrounding areas: review of their distribution and diver­sification. Review of Palaeobotany and Palynology113, 41–55.

Hints, O. & Eriksson, M. E. 2007. Diversification and bio­geography of scolecodont-bearing polychaetes in the Ordovician. Palaeogeography, Palaeoclimatology, Palaeo­ecology245, 95–114.

Hints, O., Delabroye, A., Nõlvak, J., Servais, T., Uutela, A. & Wallin, Å. 2010. Biodiversity patterns of Ordovician marine microphytoplankton from Baltica: Comparison with other fossil groups and sea-level changes. Palaeogeography, Palaeoclimatology, Palaeoecology294, 161–173.

Hints, O., Viira, V. & Nõlvak, J. 2012. Darriwilian (Middle Ordovician) conodont biostratigraphy in NW Estonia. Estonian Journal of Earth Sciences61, 210–226.

Hints, O., Martma, T., Männik, P., Nõlvak, J., Põldvere, A., Shen, Y. & Viira, V. 2014. New data on Ordovician stable isotope record and conodont biostratigraphy from the Viki reference drill core, Saaremaa Island, western Estonia. GFF136, 100–104.

Hints, O., Antonovitš, L., Bauert, G., Nestor, V., Nõlvak, J. & Tammekänd, M. 2018. CHITDB: a database for docu­menting and analysing diversification of Ordovician– Silurian chitinozoans in the Baltic region. Lethaia51, 218–227.

Kiipli, E., Kiipli, T., Kallaste, T. & Ainsaar, L. 2010. Distribution of phosphorus in the Middle and Upper Ordovician Baltoscandian carbonate palaeobasin. Estonian Journal of Earth Sciences59, 247–255.

Kozłowski, R. 1959. Un microfossile énigmatique. Acta Palaeontologica Polonica4, 273–277.

Kozłowski, R. 1965. Oeufs fossiles des Céphalopodes? Acta Palaeontologica Polonica10, 3–9.

Kröger, B. 2012. The “Vaginaten”: the dominant cephalopods of the Baltoscandian Mid Ordovician endocerid limestone. GFF134, 115–132.

Kröger, B., Franeck, F. & Rasmussen, C. M. Ø. 2019. The evolutionary dynamics of the early Palaeozoic marine biodiversity accumulation. Proceedings of the Royal Society B: Biological Sciences286, 20191634.

Laptikhovsky, V., Nikolaeva, S. & Rogov, M. 2018. Cephalopod embryonic shells as a tool to reconstruct reproductive strategies in extinct taxa: Cephalopod reproductive strategies. Biological Reviews93, 270–283.

Liang, Y., Hints, O., Luan, X., Tang, P., Nõlvak, J. & Zhan, R. 2018. Lower and Middle Ordovician chitinozoans from Honghuayuan, South China: Biodiversity patterns and response to environmental changes. Palaeogeography, Palaeoclimatology, Palaeoecology500, 95–105.

Liang, Y., Bernardo, J., Goldman, D., Nõlvak, J., Tang, P., Wang, W. & Hints, O. 2019. Morphological variation suggests that chitinozoans may be fossils of individual microorganisms rather than metazoan eggs. Proceedings of the Royal Society B: Biological Sciences286, 20191270.

Liang, Y., Hints, O., Tang, P., Cai, C., Goldman, D., Nõlvak, J., Tihelka, E., Pang, K., Bernardo, J. & Wang, W. 2020. Fossilized reproductive modes reveal a protistan affinity of Chitinozoa. Geology48, 1200–1204.

Lindskog, A., Costa, M. M., Rasmussen, C. M. Ø., Connelly, J. N. & Eriksson, M. E. 2017. Refined Ordovician timescale reveals no link between asteroid breakup and biodiversifi­cation. Nature Communications8, 14066.

Männik, P. & Viira, V. 2012. Ordovician conodont diversity in the northern Baltic. Estonian Journal of Earth Sciences61, 1–14.

Männil, R. 1966. Balti basseini areng ordoviitsiumis [Evolution of the Baltic Basin During the Ordovician]. Valgus Publishers, Tallinn, 200 pp. [in Russian].

Mathur, V. K., Shome, S., Nath, S. & Babu, R. 2014. First record of metazoan eggs and embryos from early Cambrian Chert Member of Deo ka Tibba Formation, Tal Group, Uttarakhand Lesser Himalaya. Journal of the Geological Society of India83, 191–197.

Meidla, T. 1997. Kunda Stage. In Geology and Mineral Resources of Estonia (Raukas, A. & Teedumäe, A., eds), pp. 64–66. Estonian Academy Publishers, Tallinn. 

Menezes, M., Branco, S., Miotto, M. C. & Alves-de-Souza, C. 2018. The Genus Alexandrium (Dinophyceae, Dinophyta) in Brazilian Coastal Waters. Frontiers in Marine Science5, 1–13.

Miller, M. A. 1996. Chapter 11. Chitinozoa. In Palynology: Principles and Applications. 1 (Jansonius, J. & McGregor, D. C., eds), pp. 307–336. American Association of Stratigraphic Palynologists Foundation.

Moldowan, J. M. & Talyzina, N. M. 1998. Biogeochemical evidence for dinoflagellate ancestors in the Early Cambrian. Science281, 1168–1170.

Nõlvak, J. & Grahn, Y. 1993. Ordovician chitinozoan zones from Baltoscandia. Review of Palaeobotany and Palynology79, 245–269.

Nõlvak, J., Hints, O. & Männik, P. 2006. Ordovician timescale in Estonia: recent developments. Proceedings of the Estonian Academy of Sciences, Geology54, 95–108.

Nõlvak, J., Liang, Y. & Hints, O. 2019. Early diversification of Ordovician chitinozoans on Baltica: New data from the Jägala waterfall section, northern Estonia. Palaeogeography, Palaeoclimatology, Palaeoecology525, 14–24.

Paris, F. & Mergl, M. 1984. Arenigian chitinozoans from the Klabava formation, Bohemia. Review of Palaeobotany and Palynology43, 33–65.

Paris, F. & Nõlvak, J. 1999. Biological interpretation and paleobiodiversity of a cryptic fossil group: the ‘Chitinozoan animal’. Geobios32, 315–324.

Paris, F., Grahn, Y., Nestor, V. & Lakova, I. 1999. A revised chitinozoan classification. Journal of Paleontology73, 549–570.

Paris, F., Achab, A., Asseline, E., Chen, X.-H., Grahn, Y., Nõlvak, J., Obut, O., Samuelsson, J., Sennikov, N., Vecoli, M., Verniers, J., Wang, X.-F. & Winchester-Seeto, T. 2004. Chitinozoa. In The Great Ordovician Diversification Event (Webby, B. D., Paris, F., Droser, M. & Percival, I., eds), pp. 294–311. Columbia University Press, New York.

Pärnaste, H., Bergström, J. & Zhiyi, Z. 2013. High resolution trilobite stratigraphy of the Lower–Middle Ordovician Öland Series of Baltoscandia. Geological Magazine150, 509–518.

Põldvere, A. (ed). 2010. Viki Drill Core. Estonian Geological Sections, Bulletin. 10. Geological Survey of Estonia, Tallinn, 56 pp.

Pyle, L. J., Narbonne, G. M., Nowlan, G. S., Xiao, S. & James, N. P. 2006. Early Cambrian metazoan eggs, embryos, and phosphatic microfossils from northwestern Canada. Journal of Paleontology80, 811–825.[811:ECMEEA]2.0.CO;2

Rasmussen, C. M. Ø., Ullmann, C. V., Jakobsen, K. G., Lindskog, A., Hansen, J., Hansen, T., Eriksson, M. E., Dronov, A., Frei, R., Korte, C., Nielsen, A. T. & Harper, D. A. T. 2016. Onset of main Phanerozoic marine radiation sparked by emerging Mid Ordovician icehouse. Scientific Reports6, 18884.

Rasmussen, C. M. Ø., Kröger, B., Nielsen, M. L. & Colmenar, J. 2019. Cascading trend of Early Paleozoic marine radiations paused by Late Ordovician extinctions. Proceedings of the National Academy of Sciences116, 7207–7213.

Rubinstein, C. V. & Vajda, V. 2019. Baltica cradle of early land plants? Oldest record of trilete spores and diverse cryptospore assemblages; evidence from Ordovician suc­cessions of Sweden. GFF141, 181–190.

Schmitz, B., Harper, D. A. T., Peucker-Ehrenbrink, B., Stouge, S., Alwmark, C., Cronholm, A., Bergström, S. M., Tassinari, M. & Xiaofeng, W. 2007. Asteroid breakup linked to the Great Ordovician Biodiversification Event. Nature Geoscience1, 49–53.

Schmitz, B., Farley, K. A., Goderis, S., Heck, P. R., Bergström, S. M., Boschi, S., Claeys, P., Debaille, V., Dronov, A., van Ginneken, M., Harper, D. A. T., Iqbal, F., Friberg, J., Liao, S., Martin, E., Meier, M. M. M., Peucker-Ehrenbrink, B., Soens, B., Wieler, R. & Terfelt, F. 2019. An extraterrestrial trigger for the mid-Ordovician ice age: Dust from the breakup of the L-chondrite parent body. Science Advances5, eaax4184.

Selden, P. A., Huys, R., Stephenson, M. H., Heward, A. P. & Taylor, P. N. 2010. Crustaceans from bitumen clast in Carboniferous glacial diamictite extend fossil record of copepods. Nature Communications1, 50.

Servais, T., Brocke, R., Fatka, O., LeHerisse, A. & Molyneux, S. G. 1996. Value and meaning of the term Acritarch. Acta Universitatis Carolinae Geologica40, 631–643.

Servais, T., Owen, A. W., Harper, D. A. T., Kröger, B. & Munnecke, A. 2010. The Great Ordovician Biodiversifi­cation Event (GOBE): The palaeoecological dimension. Palaeogeography, Palaeoclimatology, Palaeoecology294, 99–119.

Servais, T., Martin, R. E. & Nützel, A. 2016. The impact of the ‘terrestrialisation process’ in the late Palaeozoic: pCO2pO2, and the ‘phytoplankton blackout’. Review of Palaeobotany and Palynology224, 26–37.

Shen, Y. & Huang, D. 2008. Extant clam shrimp egg morphol­ogy: taxonomy and comparison with other fossil bran­- chiopod eggs. Journal of Crustacean Biology28, 352–360.[0352:ECSEMT]2.0.CO;2

Siveter, D. J., Siveter, D. J., Sutton, M. D. & Briggs, D. E. G. 2007. Brood care in a Silurian ostracod. Proceedings of the Royal Society B: Biological Sciences274, 465–469.

Siveter, D. J., Tanaka, G., Farrell, Ú. C., Martin, M. J., Siveter, D. J. & Briggs, D. E. G. 2014. Exceptionally preserved 450-million-year-old Ordovician ostracods with brood care. Current Biology24, 801–806.

Steiner, M., Qian, Y., Li, G., Hagadorn, J. W. & Zhu, M. 2014. The developmental cycles of early Cambrian Olivooidae fam. nov. (?Cycloneuralia) from the Yangtze Platform (China). Palaeogeography, Palaeoclimatology, Palaeoecology398, 97–124.

Strother, P. K. 1996. Chapter 5. Acritarchs. In Palynology: Princi­ples and Applications (Jansonius, J. & McGregor, D. C., eds), pp. 81–106. American Association of Stratigraphic Palynologists Foundation.

Tammekänd, M., Hints, O. & Nõlvak, J. 2010. Chitinozoan dynamics and biostratigraphy in the Väo Formation (Darriwilian) of the Uuga Cliff, Pakri Peninsula, NW Estonia. Estonian Journal of Earth Sciences59, 25–36.

Toom, U., Vinn, O., Isakar, M., Madison, A. & Hints, O. 2020. Small faecal pellets in Ordovician shelly fossils from Estonia, Baltoscandia. Estonian Journal of Earth Sciences69, 1–19.

Torsvik, T. H. & Cocks, L. R. M. 2013. Chapter 2. New global palaeogeographical reconstructions for the Early Palaeozoic and their generation. Geological Society, London, Memoirs38, 5–24.

Verniers, J., Nestor, V., Paris, F., Dufka, P., Sutherland, S. & Van Grootel, G. 1995. A global Chitinozoa biozonation for the Silurian. Geological Magazine132, 651–666.

Webby, B. D., Cooper, R. A., Bergström, S. M. & Paris, F. 2004a. Stratigraphic framework and time slices. In The Great Ordovician Biodiversification Event(Webby, B. D., Paris, F., Droser, M. L. & Percival, I. G., eds), pp. 41–47. Columbia University Press, New York.

Webby, B. D., Paris, F., Droser, M. L. & Percival, I. G. 2004b. The Great Ordovician Biodiversification Event. Columbia University Press, New York, 484 pp.

Winding Hansen, B. 2019. Copepod Embryonic Dormancy: “An Egg Is Not Just an Egg”. The Biological Bulletin237, 145–169.

Yin, Z., Zhao, D., Pan, B., Zhao, F., Zeng, H., Li, G., Bottjer, D. J. & Zhu, M. 2018. Early Cambrian animal diapause em­bryos revealed by X-ray tomography. Geology46, 387– 390.

Yin, Z., Sun, W., Liu, P., Zhu, M. & Donoghue, P. C. J. 2020. Developmental biology of Helicoforamina reveals holozoan affinity, cryptic diversity, and adaptation to heterogeneous environments in the early Ediacaran Weng’an biota (Doushantuo Formation, South China). Science Advances6, eabb0083.

Yin, Z. J. & Zhu, M. Y. 2012. New observations of the orna­mented Doushantuo embryo fossils from the Ediacaran Weng’an Biota, South China. Bulletin of Geosciences87, 171–181.

Zhang, J. 1998. Middle Ordovician conodonts from the Atlantic Faunal Region and the evolution of key conodont genera. Meddelanden från Stockholms Universitetets Institution för Geologi och Geokemi298, 5–27.

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