The genus Discoceras (Tarphyceratida, Cephalopoda; Ordovician) from Estonia and glacial erratics in north-central Europe
Abstract
The cephalopod genus Discoceras Barrande, 1867 (family Trocholitidae Chapman, 1857; order Tarphyceratida Flower, 1950) is a characteristic component of the late Middle and Late Ordovician carbonates of Baltoscandia and its glacial erratics in north-central Europe. The genus consists of tens of species, most of which are, however, poorly constrained, partly due to the type material being inaccessible or lost. Consequently, a comprehensive revision of the genus is needed. Here, we describe 39 specimens from in-situ rocks in northern Estonia and Norway, and from boulders in Pleistocene glaciofluvial sediments in Germany and Poland. Six previously described species were identified: Discoceras antiquissimum (Eichwald, 1842), D. saemanni (Hyatt, 1894), D. ievense (Balashov, 1953), D. damesii (Schröder, 1891), D. bandonis Remelé, 1890 and D. danckelmanni (Remelé, 1880). Two species were left in open nomenclature: D. cf. paopense Kröger, 2025 and D. cf. gubkovense Balashov, 1953; seven species are newly described: D. aseriense sp. nov., D. brandenburgense sp. nov., D. angustum sp. nov., D. circulare. sp. nov., D. sovaki sp. nov., D. alienum sp. nov. and D. polonicum sp. nov. The single specimen and holotype of Discoceras aseriense (Aseri Regional Stage, Darriwilian, Middle Ordovician) is the stratigraphically earliest known representative of the genus from Baltica and possibly globally. Lituites trapezoidalis is herein synonymised under the type species, Discoceras antiquissimum. A neotype is proposed for the latter, stabilising the concept of the type species and the genus Discoceras. The study showed that the separation of Discoceras at the family level is not justified and the monogeneric family Discoceratidae Hyatt, 1894 is herein synonymised under the family Trocholitidae Chapman, 1857.
References
Aubrechtová M. & Korn D. 2025. The coiled Middle Ordovician cephalopod genera Trocholites and Curtoceras (Tarphyceratida) from Baltoscandia and north-central Europe. European Journal of Taxonomy 982: 1–78. https://doi.org/10.5852/ejt.2025.982.2843
Balashov Z.G. 1953. Stratigraphic distribution of nautiloids during the pre-Baltic Ordovician. Trudy vsjesojuznogo neftjanogo nauchno-issledovatělskogo geologo-razvedochnogo Instituta (VNIGRI) 78: 197–216.
Balashov Z.G. 1962. Otryad Tarphyceratida. In: Orlov Y.A. (ed.) Osnovy Paleontologii, Mollyuski – Golovonogie 1: 77–82. Akademiya Nauk SSSR, Moskva
Balashov Z.G. 1964. Nekotorye nautiloidei endoceratoidei i actinoceratoidei Ordovika Severo-Vostoka SSSR. Ucenye zapiski naucno issledovatelskij Institut Geologii arktiki gosudarstvennogo Geologiceskogo Komiteta SSSR 6: 12–71.
Balashov Z.G. 1974. Order Tarphyceratida. In: Hardin H. (ed.) Fundamentals of Paleontology (Osnovy Paleontologii). Vol. 5, Molluska – Cephalopoda 1: 99–106. Keter Publishing House, Jerusalem.
Barrande J. 1865. Systême silurien du Centre de la Bohême; Ière partie: Recherches paléontologiques, Vol. II. Céphalopodes. Ière Série: Planches 1 à 107. Praha, Paris. Available from https://www.biodiversitylibrary.org/page/14860520 [accessed 5 Nov. 2025].
Barrande J. 1867. Systême silurien du Centre de la Bohême; Ière partie: Recherches paléontologiques, Vol. II. Texte. Classe des Mollusques, Ordre des Céphalopodes. Praha, Paris. Available from https://www.biodiversitylibrary.org/page/14886746 [accessed 5 Nov. 2025].
Barrande J. 1877. Systême silurien du Centre de la Bohême; Ière partie: Recherches paléontologiques, Vol. II. Classe des Mollusques, Ordre des Céphalopodes. Supplément et Série tardive. Praha, Paris. Available from https://www.biodiversitylibrary.org/page/14861750 [accessed 5 Nov. 2025].
Barskov I.S. 1972. Late Ordovician and Silurian Cephalopod Molluscs of Kazakhstan and Middle Asia. Akademiya Nauk USSR, Moskva.
Chapman E.J. 1857. On the occurrence of the genus Cryptoceras in Silurian rocks. Annals and Magazine of Natural History, Series 2 20: 114–117. https://doi.org/10.1080/00222935709487883
de Verneuil É.P. 1845. Paléontologie. In: Murchison R.I., de Verneuil É.P. & Keyserling A.G. (eds) Géologie de la Russie d’Europe et des Montagnes de l’Oural Vol. 2. Murray, Bertrand, London & Paris.
Dzik J. 1984. Phylogeny of the Nautiloidea. Palaeontologia Polonica 45: 1–219.
Dzik J. & Korn D. 1992. Devonian ancestors of Nautilus. Paläontologische Zeitschrift 66: 81–98. https://doi.org/10.1007/BF02989479
Ebbestad J.O.R. & Högström A.E.S. 2007. Ordovician of the Siljan district, Sweden. Sveriges geologiska Undersökning, Rapporter och Meddelanden 128: 7–26.
Eichwald E. 1840. Über das silurische Schichtensystem in Esthland. Journal für Natur-und Heilkunde 1–2: 1–210. https://doi.org/10.5962/bhl.title.150763
Eichwald E. 1842. Neuer Beitrag zur Geognosie Esthlands und Finlands. In: Eichwald E (ed.) Die Urwelt Russlands durch Abbildungen erlaeutert: 1–138. Akademie der Wissenschaften, St Petersburg.
Eichwald E.d. 1860. Lethaea Rossica ou Paléontologie de la Russie. Premier Volume. Ancienne Période. Schweizerbart, Stuttgart. https://doi.org/10.5962/bhl.title.52391
Etheridge R. 1904. On the occurrence of a lituitean in the Upper Silurian rocks of Bowning, New South Wales. Records of the Australian Museum 5: 75–77. https://doi.org/10.3853/j.0067-1975.5.1904.1037
Flower R.H. 1964. Nautiloid shell morphology. New Mexico Institute of Mining and Technology, State Bureau of Mines and Mineral Resources, Memoir 13: 1–77. https://doi.org/10.58799/M-13
Flower R.H. 1968. Some additional Whiterock cephalopods. New Mexico Institute of Mining and Technology, State Bureau of Mines and Mineral Resources, Memoir 19: 19–55.
Foerste A.F. 1925. Notes on cephalopod genera; chiefly coiled Silurian forms. Denison University Bulletin, Journal of the Scientific Laboratories 21: 1–69.
Foerste A.F. 1930. Three studies of cephalopods. Denison University Bulletin, Journal of the Scientific Laboratories 23: 265–381.
Foord A.H. 1891. Catalogue of the Fossil Cephalopoda in the British Museum, part II. Containing the remainder of the suborder Nautiloidea, consisting of the families Lituitidae, Trochoceratidae, and Nautilidae, with a supplement. Order of the Trustees, London. https://doi.org/10.5962/bhl.title.112429
Furnish W.M. & Glenister B.F. 1964. Nautiloidea-Tarphycerida. In: Moore R.C. (ed.) Treatise on Invertebrate Paleontology: K343–K368. The Geological Survey of America and The University of Kansas Press, Lawrence, KS.
Gao Y., Lai C. & Y.W. 1982. Phylum Mollusca. Class Cephalopoda. In: Xi’an Institute of Geology and Mineral Resources (ed.) Palaeontological Atlas of Northwest China, Shaanxi-Gansu, Ningxia Volume. Part 1, Precambrian and Early Palaeozoic: 187–208. Geological Publishing House, Beijing.
Hucke K. 1967. Einführung in die Geschiebeforschung (Sedimentärgeschiebe). Nederlandse Geogologische Vereiniging, Oldenzaal.
Hyatt A. 1894. Phylogeny of an acquired characteristic. Proceedings of the American Philosophical Society 32: 349–647. https://doi.org/10.5962/bhl.title.59826
Klug C., Korn D., Landman N.H., Tanabe K., De Baets K. & Naglik C. 2015. Describing ammonoid conchs. In: Klug C., Korn D., De Baets K., Kruta I. & Mapes R.H. (eds) Ammonoid Paleobiology: From Macroevolution to Paleogeography, Topics in Geobiology 44: 3–24. Springer, Dordrecht. https://doi.org/10.1007/978-94-017-9630-9_1
Korn D. 2010. A key for the description of Palaeozoic ammonoids. Fossil Record 13: 5–12. https://doi.org/10.1002/mmng.200900008
Korn D. & Klug C. 2003. Morphological pathways in the evolution of Early and Middle Devonian ammonoids. Paleobiology 29: 329–348. https://doi.org/10.1666/0094-8373(2003)029<0329:MPITEO>2.0.CO;2
Kröger B. 2008. Nautiloids before and during the origin of ammonoids in a Siluro-Devonian section in the Tafilalt, Anti-Atlas, Morocco. Special Papers in Palaeontology 79: 1–110.
Kröger B. 2013a. The cephalopods of the Boda Limestone, Late Ordovician, of Dalarna, Sweden. European Journal of Taxonomy 41: 1–110. https://doi.org/10.5852/ejt.2013.41
Kröger B. 2013b. Cambrian–Ordovician cephalopod palaeogeography and diversity. Geological Society, London, Memoirs 38: 429–448. https://doi.org/10.1144/M38.27
Kröger B. 2025. The Lyckholm acme of cephalopods – Review of the late Katian (Vormsi–Pirgu regional stages) Ordovician cephalopods of Estonia. European Journal of Taxonomy 978: 1–169. https://doi.org/10.5852/ejt.2025.978.2801
Kröger B. & Aubrechtová M. 2018. Cephalopods from reef limestone of the Vasalemma Formation, northern Estonia (latest Sandbian, Upper Ordovician) and the establishment of a local warm-water fauna. Journal of Systematic Palaeontology 16: 799–839. https://doi.org/10.1080/14772019.2017.1347212
Kröger B. & Aubrechtová M. 2019. The cephalopods of the Kullsberg Limestone Formation, Upper Ordovician, central Sweden and the effects of reef diversification on cephalopod diversity. Journal of Systematic Palaeontology 17: 961–995. https://doi.org/10.1080/14772019.2018.1491899
Kröger B., Ebbestad J.O.R., Högström A.E. & Frisk Å.M. 2011. Mass concentration of Hirnantian cephalopods from the Siljan District, Sweden; taxonomy, palaeoecology and palaeobiogeographic relationships. Fossil Record 14: 35–53. https://doi.org/10.1002/mmng.201000014
Lai C. 1982. Ordovician cephalopods from Xainza, Xizang (Tibet). Acta Palaeontologica Sinica 21: 553–559.
Lai C. 1987. Ordovician cephalopods from Mt. Querquerk (Mt. Charchag), Xinjiang. Professional Papers in Stratigraphy and Palaeontology 17: 227–246.
Lai C. & Wang M. 1981. Cephalopoda. In: Wang M. (ed.) Atlas of Palaeontology of Northwest China, Xinjiang: 115–134. Geological Publishing House, Beijing.
Lai C. & Wang M. 1986. Ordovician cephalopods from Mt. Altun area, NW China. Acta Palaeontologica Sinica 25: 248–258.
Lossen C. 1860. Über einige Lituiten. Zeitschrift der Deutschen geologischen Gesellschaft 12: 15–28. Available from https://www.biodiversitylibrary.org/page/34776055 [accessed 5 Nov. 2025].
Manda Š. & Turek V. 2018. Silurian tarphycerid Discoceras (Cephalopoda, Nautiloidea): systematics, embryonic development and paleoecology. Journal of Paleontology 92: 412–431. https://doi.org/10.1017/jpa.2017.122
Manda Š. & Turek V. 2019. Embryonic and early juvenile development in the Silurian basal nautilid Peismoceras Hyatt, 1894. Swiss Journal of Palaeontology 138: 123–139. https://doi.org/10.1007/s13358-019-00192-6
Meek F.B. & Worthen A.H. 1870. Descriptions of new species and genera of fossils from the Palaeozoic rocks of the western states. Proceedings of the Academy of Natural Sciences of Philadelphia 22: 22–56. Available from https://hdl.handle.net/10088/34362 [accessed 5 Nov. 2025].
Meek F.B. & Worthen A.H. 1873. Descriptions of invertebrates from Carboniferous system. Illinois Geological Survey Bulletin 5: 321–619. Available from https://www.biodiversitylibrary.org/page/19707315 [accessed 5 Nov. 2025].
Meidla T., Ainsaar L. & Hints O. 2014. The Ordovician System in Estonia. In: Bauert H., Hints O., Meidla T. & Männik P. (eds) 4th Annual Meeting of IGCP 591. The Early to Middle Paleozoic Revolution. Estonia, 10–19 June 2014. Abstracts and Field Guide: 116–122. University of Tartu, Tartu.
Meidla T., Ainsaar L., Hints O. & Radzevičius S. 2023. Ordovician of the Eastern Baltic palaeobasin and the Tornquist Sea margin of Baltica. Geological Society, London, Special Publications 532: 317–343. https://doi.org/10.1144/SP532-2022-141
Nakrem H.A. & Rasmussen J.A. 2013. Oslo Region, Norway. In: Calner M., Ahlberg P., Lehnert O. & Erlström M. (eds) The Lower Palaeozoic of Southern Sweden and the Oslo Region, Norway. Field Guide for the 3rd Annual Meeting of the IGCP Project 591. Sveriges geologiska Undersökning Rapporter och Meddelanden: 57–85.
Neben W. & Krueger H.-H. 1971. Fossilien ordovizischer Geschiebe. Staringia 1: 1–50.
Neben W. & Krueger H.-H. 1973. Fossilien ordovizischer und silurischer Geschiebe. Staringia 2: 51–109.
Nielsen A.T., Ahlberg P., Ebbestad J.O.R., Hammer Ø., Harper D.A.T., Lindskog A., Rasmussen C.M.Ø. & Stouge S. 2023. The Ordovician of Scandinavia: A revised regional stage classification. Geological Society, London, Special Publications 532: 267–315. https://doi.org/10.1144/SP532-2022-157
Noetling F. 1883. Die Cambrischen und Silurischen Geschiebe der Provinzen Ost- und West-Preussen. Jahrbuch der Königlich Preussischen Geologischen Landesanstalt und Bergakademie zu Berlin 1882: 261–324. Available from https://www.biodiversitylibrary.org/page/51411914 [accessed 5 Nov, 2025].
Pohle A., Kröger B., Warnock R.C.M., King A.H., Evans D.H., Aubrechtová M., Cichowolski M., Fang X. & Klug C. 2022. Early cephalopod evolution clarified through Bayesian phylogenetic inference. BMC Biology 20: 88. https://doi.org/10.1186/s12915-022-01284-5
QGIS Development Team 2024. QGIS 3.34.13. Geographic information system. QGIS Association. Available from https://github.com/qgis/QGIS/commit/222b5995 [accessed 5 Nov. 2025].
Rasmussen J.A. & Surlyk F. 2012. Rare finds of the coiled cephalopod Discoceras from the Upper Ordovician of Bornholm, Denmark. Bulletin of the Geological Society of Denmark 60: 15–22. https://doi.org/10.37570/bgsd-2012-60-02
Reed F.R.C. 1912. Ordovician and Silurian fossils from the central Himalayas. Palaeontologia Indica Series 15 7 (Memoirs 2): 1–168.
Remelé A. 1880. Ueber einige neue oder seltene Versteinerungen aus silurischen Diluvialgeschieben der Gegend von Eberswalde. In: Festschrift für die Fünfzigjährige Jubelfeier der Forstakademie Eberswalde: 179–252. Julius Springer, Berlin.
Remelé A. 1886. Systematic der Lituiten. Zeitschrift der Deutschen geologischen Gesellschaft 38: 467–468. Available from https://www.biodiversitylibrary.org/page/43541565 [accessed 5 Nov. 2025].
Remelé A. 1890. Untersuchungen über die versteinerungsführenden Diluvialgeschiebe des norddeutschen Flachlandes mit besonderer Berücksichtigung der Mark Brandenburg. Springer, Berlin, Heidelberg. https://doi.org/10.1007/978-3-662-32621-3
Roemer F. 1861. Die fossile Fauna der silurischen Diluvial-Geschiebe von Sadewitz bei Oels in Nieder-Schlesien: Eine palaeontologische Monographie. Nischkowsky, Breslau.
Roemer F. 1885. Lethaea erratica oder Aufzählung und Beschreibung der in der norddeutschen Ebene vorkommenden Diluvial-Geschiebe nordischer Sedimentär-Gesteine. Paläontologische Abhandlungen 2: 248–420. Available from https://www.biodiversitylibrary.org/page/11307585 [accessed 5 Nov. 2025].
Rüdiger H. 1889. Über die Silur-Cephalopoden aus den mecklenburgischen Diluvialgeschieben. Philosophische Facultät. Universität Rostock, Güstrow, Rostock. https://doi.org/10.5962/bhl.title.14078
Saemann L. 1853. Ueber die Nautiliden. Palaeontographica 3: 121–167. Available from https://www.biodiversitylibrary.org/page/33098171 [accessed 5 Nov. 2025].
Saladžius V. 1966. Mollusc fauna of the Silurian deposits of the South of the East Baltic territory. Paleontology and Stratigraphy of the Baltic and Byelorussia 1: 31–73.
Schmidt F. 1861. Untersuchungen über die Silurische Formation von Ehstland, Nord-Livland und Ösel. Archiv für die Naturkunde Liv-, Ehst- und Kurlands, 1. Serie, Mineralogische Wissenschaften, nebst Chemie, Physik und Erdbeschreibung 2: 1–248.
Schröder H. 1891. Untersuchungen über silurische Cephalopoden. Palaeontologische Abhandlungen, Neue Folge 1: 1–48. https://doi.org/10.5962/bhl.title.25535
Strand T. 1933. The Upper Ordovician cephalopods of the Oslo area. Norsk geologisk Tidsskrift 14: 1–117.
Stumbur H.A. 1959. On the embryonic shells of some Ordovician Tarphyceratida. Paleontologitscheskij Zhurnal 1959: 25–29.
Stumbur H.A. 1962. Rasprostranenie nautiloidei v ordovike Estonii (s opisaniem nekotorykh novykh rodov). Trudy Instituta geologii Akademii Nauk estonskoi SSR (ENSV Teaduste Akadeemia geoloogia Instituudi Uurimused) 10: 131–147.
Sweet W.C. 1958. The middle Ordovician of the Oslo region, Norway. 10. Nautiloid cephalopods. Norsk geologisk Tidsskrift 38: 1–176.
Teichert C. 1930. Die Cephalopoden-Fauna der Lyckholm-Stufe des Ostbaltikums. Paläontologische Zeitschrift 12: 264–312. https://doi.org/10.1007/BF03044452
Thorslund P. 1936. Siljanområdets brännkalkstenar och kalkindustri. Sveriges geologiska Undersökning, Afhandlingar och Uppsater, C 398: 1–57.
Ulrich E.O., Foerste A.F., Miller A.K. & Furnish W.M. 1942. Ozarkian and Canadian Cephalopods Part I: Nautilicones. Geological Society of America Special Papers 37: 1–157. https://doi.org/10.1130/SPE37-p1
Whiteaves J.F. 1897. The fossils of the Galena-Trenton and Black River Formations of Lake Winnipeg and its vicinity. In: Geological Survey of Canada, Palaeozoic Fossils, Vol. 3, Part 3: 129–242. B.E. Dawson, Geological Survey of Canada. https://doi.org/10.4095/131599
Zou X. 1983. Silurian Nautiloids from Bateaobao, Darhan Muminglan Joint Banner, Inner Mongolia, In: Li W., Rong J. & Dong D. (eds) Silurian and Devonian Rocks and Faunas of the Bateaobao Area in Darhan Mumingan Joint Banner, Inner Mongolia: 165–173. The People’s Publishing House of Inner Mongolia, Nanjing.
Copyright (c) 2026 Martina Aubrechtová, Dieter Korn, Björn Kröger
This work is licensed under a Creative Commons Attribution 4.0 International License.
Creative Commons Copyright Notices
Authors who publish with this journal agree to the following terms:
- Authors retain copyright and grant the journal right of first publication with the work simultaneously licensed under a Creative Commons Attribution License (CC BY 4.0) that allows others to share the work with an acknowledgement of the work's authorship and initial publication in this journal.
- Authors are able to enter into separate, additional contractual arrangements for the non-exclusive distribution of the journal's published version of the work (e.g., post it to an institutional repository or publish it in a book), with an acknowledgement of its initial publication in this journal.
- Authors are NOT PERMITTED to post their submitted work online (e.g., in institutional repositories or on personal websites) prior to publication, as it may lead to nomenclatural issues.
