In situ chains of Margachitina margaritana (Eisenack, 1938): a third chitinozoan egg-laying strategy

 

Authors: Vodička J, Botting JP, Muir LA, Fatka O

Published in: Bulletin of Geosciences, volume 100, issue 4; pages: 677 - 684; Received 2 July 2025; Accepted in revised form 3 November 2025; Online 31 December 2025

Keywords: Chitinozoa, Silurian, Chitinozoophoran, catenary structures, chains, egg mass,

full text (PDF, 15.15 MB)

Export to RIS

 

Abstract

There are two competing scenarios of chitinozoan affinity: metazoan eggs versus protists. Natural aggregates (clusters and chains) of chitinozoans provide evidence that can distinguish between these possibilities. In this paper, a natural assemblage of the chitinozoan Margachitina margaritana (Eisenack, 1938) from Wenlock (Silurian) rocks of the Welsh Basin, UK is described. The chitinozoan vesicles are arranged in an array of short curved chains. Based on the morphological arrangement and sedimentology, these chains are interpreted as having originated from oviposition and thus as consisting of metazoan eggs; the assemblage indicates a strategy of laying multiple short egg-chains within a small area. This arrangement is perfectly consistent with the polycluster hypothesis, as the morphology of M. margaritana excludes formation of polyclusters. The impossibility of interpreting the assemblage as a protist-produced structure further supports a metazoan origin for chitinozoans.

References

Cramer, F.H. & Díez, M.d.C.R. 1974. Polymorphism in Silurian chitinozoans from Tunisia. Palaeontographica, Abteilung B, Paläophytologie 148, 1-8.

Eisenack, A. 1931. Neue Mikrofossilien des baltischen Silurs. I. Palaeontologische Zeitschrift 13, 74-118.View article

Eisenack, A. 1938. Neue Mikrofossilien des baltischen Silurs. IV. Palaeontologische Zeitschrift 19, 217-243.View article

Gabbott, S.E., Aldridge, R.J. & Theron, J.N. 1998. Chitinozoan chains and cocoons from the Upper Ordovician Soom Shale Lagerstätte, South Africa: implications for affinity. Journal of the Geological Society 155, 447-452.View article

Grahn, Y. 1981. Ordovician Chitinozoa from the Stora Åsbotorp boring in Västergötland, south-central Sweden. Sveriges Geologiska Undersökning, Serie C 787, 1-51.

Jaglin, J.C. & Paris, F. 1992. Exemples de tératologie chez les Chitinozoaires du Pridoli de Libye et implications sur la signification biologique du groupe. Lethaia 25, 151-164.View article

Jenkins, W.A.M. 1970. Chitinozoa, 1-22. In Perkins, B.F. (ed.) Geoscience and Man 1. Baton Rouge, Louisiana.View article

Kozłowski, R. 1963. Sur la nature des Chitinozoaires. Acta Palaeontologica Polonica 8, 425-449.

Laufeld, S. 1974. Silurian Chitinozoa from Gotland. Fossils and Strata 51, 1-130.View article

Liang, Y., Bernardo, J., Goldman, D., Nolvak, 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 286, 20191270.View article

Liang, Y., Hints, O., Tang, P., Cai, C., Goldman, D., Nolvak, J., Tihelka, E., Pang, K., Bernardo, J. & Wang, W. 2020. Fossilized reproductive modes reveal a protistan affinity of Chitinozoa. Geology 48, 1200-1204.View article

Mullins, G.L. & Loydell, D.K. 2001. Integrated Silurian chitinozoan and graptolite biostratigraphy of the Banwy River section, Wales. Palaeontology 44, 731-781.View article

Mullins, G.L. & Loydell, D.K. 2002. Integrated lower Silurian chitinozoan and graptolite biostratigraphy of Buttington Brick Pit, Wales. Geological Magazine 139, 89-96.View article

Nestor, V. 1994. Early Silurian chitinozoans in Estonia and North Latvia. 195 pp. Estonian Academy Publishers, Talinn.

Nestor, V. 1998. Chitinozoan biofacies of late early Llandovery (Coronograptus cyphus) age in the East Baltic. Proceedings of the Estonian Academy of Sciences, Geology 47, 219-228.View article

Paris, F. 1981. Les chitinozoaires dans le Paleozoique du Sud-Ouest de l’Europe: (cadre géologique, étude systématique, biostratigraphie). Société géologique et minéralogique de Bretagne 26, 1-496.

Paris, F. 1996. Chitinozoan biostratigraphy and palaeoecology, 531-552. In Jansonius, J. & McGregor, D.C. (eds) Palynology: principles and applications. American Association of Stratigraphic Palynologists Foundation 2.

Paris, F. 2006. Chitinozoans: A Fascinating and Mysterious Microfossil Group. 81 pp. Rapport interne de l’université de Rennes I, France.

Paris, F. & Nolvak, J. 1999. Biological interpretation and paleobiodiversity of a cryptic fossil group: The “chitinozoan animal”. Geobios 32, 315-324.View article

Paris, F. & Verniers, J. 2005. Chitinozoa, 248-440. In Selley, R.C., Cocks, L.R.M. & Plimer, I.R. (eds) Encyclopedia of geology. Elsevier Academic, Oxford.

Schofield, D. 2009. What’s in the Welsh Basin? insights into the evolution of Central Wales and the Welsh Borderlands during the Lower Palaeozoic. Proceedings of the Shropshire Geological Society 14, 1-17.

Schofield, D.I., Davies, J.R., Waters, R.A., Wilby, P.R., Williams, M. & Wilson, D. 2004. Geology of the Builth Wells district: a brief explanation of the geological map sheet 196 Builth Wells. British Geological Survey.

Schweinenberg, J. 1987. Silurische Chitinozoen aus der Provinz Palencia (Kantabrisches Gebirge, N-Spanien). Göttinger Arbeiten zur Geologie und Paläontologie 33, 1-122.

Sutherland, S.J.E. 1994. Ludlow Chitinozoans from the type area and adjacent regions. Monographs of the Palaeontographical Society 148, 1-104.View article

Vandenbroucke, T.R., Armstrong, H.A., Williams, M., Paris, F., Sabbe, K., Zalasiewicz, J.A., Nolvak, J. & Verniers, J. 2010. Epipelagic chitinozoan biotopes map a steep latitudinal temperature gradient for earliest Late Ordovician seas: implications for a cooling Late Ordovician climate. Palaeogeography, Palaeoclimatology, Palaeoecology 294, 202-219.View article

Vandenbroucke, T.R., Munnecke, A., Leng, M.J., Bickert, T., Hints, O., Gelsthorpe, D., Maier, G. & Servais, T. 2013. Reconstructing the environmental conditions around the Silurian Ireviken Event using the carbon isotope composition of bulk and palynomorph organic matter. Geochemistry, Geophysics, Geosystems 14, 86-101.View article

Verniers, J. 1999. Calibration of Wenlock Chitinozoa versus graptolite biozonation in the Wenlock of Builth Wells district (Wales, UK), compared with other areas in Avalonia and Baltica. Bollettino della Societa Paleontologica Italiana 38, 359-380.

Verniers, J., Nestor, V., Paris, F., Dufka, P., Sutherland, S. & Van Grootel, G. 1995. A global Chitinozoa biozonation for the Silurian. Geological Magazine 132, 651-666.View article

Vodička, J. & Manda, Š. 2019. A taxonomical and statistical study of chitinozoan distribution across the lundgreni Event (Wenlock, Silurian) from the Prague Basin, Czech Republic: A specific pattern driven by ecological changes. Marine Micropaleontology 149, 44-63.View article

Vodička, J., Muir, L.A., Botting, J.P., Špillar, V. & Fatka, O. 2022. Palaeobiological significance of chitinozoan clusters with parallel vesicles. Marine Micropaleontology 172, 102109.View article

Williams, M. & Zalasiewicz, J. 2004. The Wenlock Cyrtograptus species of the Builth Wells district, central Wales. Palaeontology 47, 223-263. DO 10.1111/j.0031-0239.2004.00372.x

Zalasiewicz, J. & Williams, M. 1999. Graptolite biozonation of the Wenlock Series (Silurian) of the Builth Wells district, central Wales. Geological Magazine 136, 263-283.View article

Zalasiewicz, J.A., Taylor, L., Rushton, A.W.A., Loydell, D.K., Rickards, R.B. & Williams, M. 2009. Graptolites in British stratigraphy. Geological Magazine 146, 785-850.View article