The Late Ordovician Baltic Palaeobasin (BPB) offered a favourable environment for a diverse and abundant ostracod fauna to thrive across the basin. A short period of unstable environmental conditions at the end of the Ordovician, the Hirnantian glaciation, and the concurrent extinction event completely rearranged the ostracod associations. Statistical analyses reveal temporal (diverse pre-glacial, more uniform glacial and poorly diverse post-glaciation faunas) and geographical (upper shelf and middle shelf faunas) separation of ostracod associations in the BPB. The geographical division applies to the pre-glacial and glacial faunas only; the scanty post-glacial fauna found in deeper-water sections is uniform. Ostracod associations are distinct both in a temporal and geographical sense. Juxtaposing ostracod data with δ13C curves shows that the typical Hirnantian Harpabollia harparum fauna in the BPB appeared near the peak of a δ13C excursion. This might explain why the H. harparum fauna seems to appear first in deeper-water sections and is absent or appears later in shallower-water sections. The majority of the nearshore sections in Estonian and Lithuanian shelves lack most or all of the Hirnantian strata. The lowermost Hirnantian is preserved in only a few sections (e.g. Männamaa and Puhmu in Estonia).
The appearance of the post-glacial ostracod fauna, which most probably was a survival fauna rather than a recovery fauna, is related to the falling limb of the δ13C curve. The appearance of this fauna was previously considered as a marker of the Ordovician–Silurian boundary in the region but, according to the present understanding, took place in the late Hirnantian.
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, Palaeoecology, 294, 189–201.
https://doi.org/10.1016/j.palaeo.2010.01.003
Ainsaar, L., Truumees, J. & Meidla, T. 2015. The position of the Ordovician–Silurian boundary in Estonia tested by high-resolution δ13C chemostratigraphic correlation. In Chemostratigraphy: Concepts, Techniques and Applications (Ramkumar, M., ed.), pp. 395–412. Elsevier, Amsterdam.
https://doi.org/10.1016/B978-0-12-419968-2.00015-7
Bauert, H., Ainsaar, L., Põldsaar, K & Sepp, S. 2014. δ13C chemostratigraphy of the Middle and Upper Ordovician succession in the Tartu-453 drillcore, southern Estonia, and the significance of the HICE. Estonian Journal of Earth Sciences, 63, 195–200.
https://doi.org/10.3176/earth.2014.18
Bergström, S. M. & Bergström, J. 1996. The Ordovician–Silurian boundary successions in Östergötland and Västergötland, S. Sweden. GFF, 118, 25–42.
https://doi.org/10.1080/11035899609546227
Bergström, S. M., Xu, C., 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. Lethaia, 42, 97–107.
https://doi.org/10.1111/j.1502-3931.2008.00136.x
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. GFF, 133, 149–171.
https://doi.org/10.1080/11035897.2011.622049
Berry, W. B. N & Boucot, A. J. 1973. Glacio-eustatic control of Late Ordovician–Early Silurian platform sedimentation and faunal changes. Geological Society of America Bulletin, 84, 275–284.
https://doi.org/10.1130/0016-7606(1973)84<275:GCOLOS>2.0.CO;2
Boomer, I., Horne, D. J. & Slipper, I. J. 2003. The use of ostracods in paleoenvironmental studies, or what can you do with an ostracod shell? Paleontological Society Papers, 9, 153–180.
https://doi.org/10.1017/S1089332600002199
Brenchley, P. J. 2004. End Ordovician extinction. In Mass Extinctions and Their Aftermath (Hallam, A. & Wignall, B. P., eds), pp. 81–83. Oxford University Press.
Brenchley, P. J. & Newall, G. 1984. Late Ordovician environmental changes and their effect on faunas. In Aspects of the Ordovician System (Bruton, D. L., ed.), Palaeontological Contributions from the University of Oslo, 295, 65–79.
Brenchley, P. J., Marshall, J. D., Carden, G. A. F., Robertson, D. B. R., Long, D. G. F., Meidla, T., Hints, L. & Anderson, T. F. 1994. Bathymetric and isotopic evidence for a short-lived Late Ordovician glaciation in a greenhouse period. Geology, 22, 295–298.
https://doi.org/10.1130/0091-7613(1994)022<0295:BAIEFA>2.3.CO;2
Brenchley, P. J., Carden, G. A., Hints, L., Kaljo, D., Marshall, J. D., Martma, T., Meidla, T. & Nõlvak, J. 2003. High-resolution stable isotope stratigraphy of Upper Ordovician sequences: Constraints on the timing of bioevents and environmental changes associated with mass extinction and glaciation. Geological Society of America Bulletin, 115, 89–104.
https://doi.org/10.1130/0016-7606(2003)115<0089:HRSISO>2.0.CO;2
Buggisch, W., Joachimski, M. M., Lehnert, O., Bergström, S. M., Repetski, J. E. & Webers, G. F. 2010. Did intense volcanism trigger the first Late Ordovician icehouse? Geology, 38, 327–330.
https://doi.org/10.1130/G30577.1
Candela, Y. 2015. Evolution of Laurentian brachiopod faunas during the Ordovician Phanerozoic sea level maximum. Earth-Science Reviews, 141, 27–44.
https://doi.org/10.1016/j.earscirev.2014.11.012
Chen, X., Rong, J., Mitchell, C. E., Harper, D. A. T., Fan, J., Zhan, R., Zhang, Y., Li, R. & Wang, Y. 2000. Late Ordovician to earliest Silurian graptolite and brachiopod biozonation from the Yangtze region, South China with a global correlation. Geological Magazine, 137, 623–650.
https://doi.org/10.1017/S0016756800004702
Clapham, M. E. 2011. Ordination methods and the evaluation of Ediacaran communities. In Quantifying the Evolution of Early Life (Laflamme, M., Schiffbauer, J. D. & Dornbos, S. Q., eds), Topics in Geobiology, 36, 3–21.
https://doi.org/10.1007/978-94-007-0680-4_1
Correa-Metrio, A., Dechnik, Y., Lozano-García, S. & Caballero, M. 2014. Detrended correspondence analysis: A useful tool to quantify ecological changes from fossil data sets. Boletín de la Sociedad Geológica Mexicana, 66, 135–143.
https://doi.org/10.18268/BSGM2014v66n1a10
Finnegan, S., Bergmann, K., Eiler, J. M., Jones, D. S., Fike, A., Eisenman, I., Hughes, N. C., Tripati, A. K. & Fischer, W. W. 2011. The magnitude and duration of late Ordovician–Silurian glaciation. Science, 331, 903–906.
https://doi.org/10.1126/science.1200803
Finnegan, S., Heim, N. A., Shanan, E. P. & Fisher, W. W. 2012. Climate change and the selective signature of the Late Ordovician mass extinction. PNAS, 109, 6829–6834.
https://doi.org/10.1073/pnas.1117039109
Hallam, A. & Wignall, P. B. 1997. Mass Extinctions and Their Aftermath. Oxford University Press, 328 pp.
Hammarlund, E. U., Dahl, T. W., Harper, D. A. T., Bond, D. P. G., Nielsen, A. T., Bjerrum, C. J., Schovsbo, N. H., Schönlaub, H. P., Zalasiewicz, J. A. & Canfield, D. E. 2012. A sulfidic driver for the end-Ordovician mass extinction. Earth and Planetary Science Letters, 331–332, 128–139.
https://doi.org/10.1016/j.epsl.2012.02.024
Hammer, Ø. & Harper D. A. T. 2005. Paleontological Data Analysis. Blackwell Publishing, 344 pp.
https://doi.org/10.1002/9780470750711
Hammer, Ø., Harper, D. A. T. & Ryan, P. D. 2001. PAST: Paleontological Statistics software package for education and data analysis. Palaeontologica Electronica, 4(1), 9 pp.
Harper, D. A. T. & Hints, L. 2015. Hirnantian (Late Ordovician) brachiopod faunas across Baltoscandia: A global and regional context. Palaeogeography, Palaeoclimatology, Palaeoecology, 444, 71–83.
https://doi.org/10.1016/j.palaeo.2015.11.044
Harper, D. A. T., Hammarlund, E. U. & Rasmussen, C. M. Ø. 2014. End Ordovician extinctions: a coincidence of causes. Gondwana Research, 25, 1294–1307.
https://doi.org/10.1016/j.gr.2012.12.021
Harris, M. T., Sheehan, P. M., Ainsaar, L., Hints, L., Männik, P., Nõlvak, J. & Rubel, M. 2004. Upper Ordovician sequences of western Estonia. Palaeogeography, Palaeoclimatology, Palaeoecology, 210, 135–148.
https://doi.org/10.1016/j.palaeo.2004.02.045
Heberle, H., Meirelles, G. V., da Silva, F. R., Telles, G. P. & Minghim, R. 2015. InteractiVenn: a web-based tool for the analysis of sets through Venn diagrams. BMC Bioinformatics, 16, 169.
https://doi.org/10.1186/s12859-015-0611-3
Herrmann, A. D., Macleod, K. G. & Leslie, S. A., 2010. Did a volcanic mega-eruption cause global cooling during the late Ordovician? Palaios, 25, 831–836.
https://doi.org/10.2110/palo.2010.p10-069r
Hints, L. & Männik, P. 2014. Stop A10: Porkuni quarry. In 4th Annual Meeting of IGCP 591, Estonia, 10–19 June 2014, Abstracts and Field Guide (Bauert, H., Hints, O., Meidla, T. & Männik, P., eds), pp. 167−172. University of Tartu.
Hints, L., Meidla, T., Nõlvak, J. & Sarv, L. 1989. Some specific features of the Late Ordovician evolution in the Baltic basin. Proceedings of the Academy of Sciences of the Estonian SSR, Geology, 38, 83–87.
Hints, L., Oraspõld, A. & Kaljo, D. 2000. Stratotype of the Porkuni Stage with comments on the Röa Member (uppermost Ordovician, Estonia). Proceedings of the Estonian Academy of Sciences, Geology, 49, 177–199.
Hints, L., Hints, O., Kaljo, D., Kiipli, T., Männik, P., Nõlvak, J. & Pärnaste, H. 2010. Hirnantian (latest Ordovician) bio- and chemostratigraphy of the Stirnas-18 core, western Latvia. Estonian Journal of Earth Sciences, 59, 1–24.
https://doi.org/10.3176/earth.2010.1.01
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. GFF, 136, 100–104.
https://doi.org/10.1080/11035897.2013.873989
Kaljo, D., Hints, L., Martma, T. & Nõlvak, J. 2001. Carbon isotope stratigraphy in the latest Ordovician of Estonia. Chemical Geology, 175, 49–59.
https://doi.org/10.1016/S0009-2541(00)00363-6
Kaljo, D., Martma, T., Männik, P. & Viira, V. 2003. Implications of Gondwana glaciations in the Baltic late Ordovician and Silurian and a carbon isotopic test of environmental cyclicity. Bulletin de la Societe Geologique de France, 174, 59–66.
https://doi.org/10.2113/174.1.59
Kaljo, D., Hints, L., Männik, P. & Nõlvak, J. 2008. The succession of Hirnantian events based on data from Baltica: brachiopods, chitinozoans, conodonts, and carbon isotopes. Estonian Journal of Earth Sciences, 57, 197–218.
https://doi.org/10.3176/earth.2008.4.01
Kump, L. R., Arthur, M. A., Patzkowsky, M. E., Gibbs, M. T., Pinkus, D. S. & Sheehan, P. M. 1999. A weathering hypothesis for glaciation at high atmospheric pCO2 during the Late Ordovician. Palaeogeography, Palaeoclimatology, Palaeoecology, 152, 173–187.
https://doi.org/10.1016/S0031-0182(99)00046-2
Lapinskas, P. 2004. Silūras [Silurian]. In Evolution of Earth Crust and Its Resources in Lithuania (Baltrūnas, V., ed.), pp. 66–72. Geologijos ir geografijos institutas, Vilniaus Universitetas [in Lithuanian].
Laškovas, J. 2004. Ordovikas [Ordovician]. In Evolution of Earth Crust and Its Resources in Lithuania (Baltrūnas, V., ed.), pp. 56–66. Geologijos ir geografijos institutas, Vilniaus Universitetas [in Lithuanian].
Lenton, T. M., Crouch, M., Johnson, M., Pires, N. & Dolan, L. 2012. First plants cooled the Ordovician. Nature Geoscience, 5, 86–89.
https://doi.org/10.1038/ngeo1390
Long, A. J., Large, R. R., Lee, M. S. Y., Benton, M. J., Danyushevsky, L. D., Chiappe, L. M., Halpin, J. A., Cantrill, D. & Lottermoser, B. 2015. Severe selenium depletion in the Phanerozoic oceans as a factor in the three global mass extinction events. Gondwana Research, 36, 209–218.
https://doi.org/10.1016/j.gr.2015.10.001
Lukševičs, E., Stinkulis, Ģ., Mūrnieks, A. & Popovs, K. 2012. Geological evolution of the Baltic Artesian Basin. In Highlights of Groundwater Research in the Baltic Artesian Basin (Dēliņa, A., Kalvāns, A., Saks, T., Bethers, U. & Vircavs, V., eds), pp. 7–52. University of Latvia, Riga.
Männik, P. 2014. The Silurian System in Estonia. In 4th Annual Meeting of IGCP 591, Estonia, 10–19 June 2014, Abstracts and Field Guide (Bauert, H., Hints, O., Meidla, T. & Männik, P., eds), pp. 123–128. University of Tartu, Tartu.
Männil, R. & Meidla, T. 1994. The Ordovician System of the East European Platform (Estonia, Latvia, Lithuania, Byelorussia, parts of Russia, the Ukraine and Moldova). In The Ordovician System of the East European Platform and Tuva (Southeastern Russia) (Webby, B. D. & Williams, S. H., eds), IUGS Publication, 28A, 1–52.
Marshall, J. D. & Middleton, P. D. 1990. Changes in marine isotopic composition and the late Ordovician glaciation. Journal of the Geological Society London,147, 1–4.
https://doi.org/10.1144/gsjgs.147.1.0001
Meidla, T. 1996a. Latest Ordovician ostracods of Baltoscandia. In WOGOGOB-94 Symposium, Working Group of Ordovician Geology of Baltoscandia, Bornholm-94 (Stouge, S., ed.), Geological Survey of Denmark and Greenland, 98, 65–71.
Meidla, T. 1996b. Late Ordovician ostracodes of Estonia. Fossilia Baltica, 2, 1–222.
Meidla, T. 1998. Ordovician. In Tartu (453) Drillcore (Põldvere, A., ed.), Estonian Geological Sections, 1, 11–17.
Meidla, T. 2001. Distribution of ostracodes in the Valga (10) section. In Valga 10 Drill Core (Põldvere, A., ed.), Estonian Geological Sections, 3, 14–16.
Meidla, T. 2007. Ostracods from the Upper Ordovician Borenshult fauna, Sweden. GFF, 129, 123–132.
https://doi.org/10.1080/11035890701292123
Meidla, T. & Tinn, O. 2008. Distribution of Upper Ordovician ostracods. In Männamaa (F-367) Drill Core (Põldvere, A., ed.), Estonian Geological Sections, 9, 24–27.
Meidla, T., Ainsaar, L. & Truuver, K. 2011. Ostracods in Baltoscandia through the Hirnantian crisis. Cuadernos del Museo Geominero, 14, 353–357.
Meidla, T., Tinn, O., Salas, M. J., Williams, M., Siveter, D., Vandenbroucke, T. & Sabbe, K. 2013. Biogeographical patterns of Ordovician ostracods. In Early Palaeozoic Palaeobiogeography and Palaeogeography (Harper, D. A. T. & Servais, T., eds), Geological Society, London, Memoirs, 38, 337−354.
https://doi.org/10.1144/M38.21
Meidla, T., Ainsaar, L. & Hints, O. 2014. The Ordovician System in Estonia. In 4th Annual Meeting of IGCP 591, Estonia, 10–19 June 2014, Abstracts and Field Guide (Bauert, H., Hints, O., Meidla, T. & Männik, P., eds), pp. 116–122. University of Tartu, Tartu.
Modliński, Z. & Podhalańska, T. 2010. Outline of the lithology and depositional features of the lower Paleozoic strata in the Polish part of the Baltic region. Geological Quarterly, 54, 109–121.
Mohibullah, M., Williams, M., Vandenbroucke, T. R. A., Sabbe, K. & Zalasiewicz, J. A. 2012. Marine ostracod provinciality in the Late Ordovician of Palaeocontinental Laurentia and its environmental and geographical expression. PLoS ONE, 7, e41682.
https://doi.org/10.1371/journal.pone.0041682
Morris, J. L., Puttick, M. N., Clark, J. W., Edwards, D., Kenrick, P., Pressel, S., Wellman, C. H., Yang, Z., Schneider, H. & Donoghue, P. C. J. 2018. The timescale of early land plant evolution. PNAS, 115, 10.
https://doi.org/10.1073/pnas.1719588115
Nõlvak, J., Hints, O. & Männik, P. 2006. Ordovician timescale in Estonia: recent developments. Proceedings of the Estonian Academy of Sciences, Geology, 55, 95–108.
Põldvere, A. 1998. Tartu (453) drill core. Estonian Geological Sections, 1, 1–48.
Pranskevičius, A. A. 1971. K paleontologicheskoj kharakteristike nizhnego silura Yuzhnoj Pribaltiki (dannye izucheniya ostrakod) [To the paleontological characteristic of the Lower Silurian of the southern Baltic area (data of the Ostrakod Study]. In Paleontologiya i stratigrafiya Pribaltiki i Belorussii, III [Palaeontology and Stratigraphy of the Baltic and the Byelorussia, III] (Grigelis, A. A., ed.), pp. 61–70. Mintis, Vilnius [in Russian, with English summary].
Pranskevičius, A. 1972. Ostrakody silura Yuzhnoj Pribaltiki [South Baltic Silurian Ostracoda]. Izvestiya akademii nauk LitNIGRI (Transactions of the Lithuanian Scientific-Research Geological Survey Institute), 15, 1–280 [in Russian].
Rasmussen, C. M. Ø. & Harper, D. A. T. 2011. Did the amalgamation of continents drive the end Ordovician mass exctinction? Palaeogeography, Palaeoclimatology, Palaeoecology, 311, 48–62.
https://doi.org/10.1016/j.palaeo.2011.07.029
Reily, L., Adôrno, R. R., do Carmo, D. A., Salas, M. J., Cardoso da Silvia Rodrigues, L., Denezine, M. & Zabini, C. 2018. Tridimensional ostracoda assemblage from Vila Maria Formation, Ordovician/Silurian, Paraná Basin Brazil. In Anais do 49º Congresso Brasileiro de Geologia, 20 a 24 de agosto de 2018 – Rio de Janeiro (Palermo, N., de Araújo, H. I. Jr, Machado, F. B., Corval, A., de Castro Valente, S. & Dal’ Bó, P. F., eds), p. 1365.
Rong, J., Jin, J., Zhan, R. & Bergström, J. 2008. The earliest known Stegerhynchus (Rhynchonellida, Brachiopoda) from the Hirnantian strata (uppermost Ordovician) at Borenshult, Östergötland, Sweden. GFF, 130, 21–30.
https://doi.org/10.1080/11035890801301021
Rosenau, N. A., Herrmann, A. D. & Leslie, S. A. 2012. Conodont apatite δ18O values from a platform margin setting, Oklahoma, USA: Implications for initiation of Late Ordovician icehouse conditions. Palaeogeography, Palaeoclimatology, Palaeoecology, 315–316, 172–180.
https://doi.org/10.1016/j.palaeo.2011.12.003
Saltzman, M. R. & Young, S. A. 2005. Long-lived glaciation in the Late Ordovician? Isotopic and sequence-stratigraphic evidence from western Laurentia. Geology, 33, 109–112.
https://doi.org/10.1130/G21219.1
Sarv, L. 1970. Ostrakody [Ostracodes]. In Silur Éstonii [The Silurian of Estonia] (Kaljo, D., ed.), pp. 157–170. Valgus, Tallinn [in Russian].
Schallreuter, R. E. L. & Siveter, D. J. 1985. Ostracodes across the Iapetus Ocean. Palaeontology, 28, 577–598.
Sell, B., Ainsaar, L. & Leslie, S. 2013. Precise timing of the Late Ordovician (Sandbian) super-eruptions and associated environmental, biological, and climatological events. Journal of the Geological Society London, 170, 711–714.
https://doi.org/10.1144/jgs2012-148
Sheehan, P. 1973. The relation of Late Ordovician glaciation to the Ordovician–Silurian changeover in North American brachiopod faunas. Lethaia, 6, 147–154.
https://doi.org/10.1111/j.1502-3931.1973.tb01188.x
Sidaravičiene, N. 1992. Ostrakody ordovika Litvy [Ordovician Ostracods of Lithuania]. LitNIGRI, Vilnius, 252 pp. [in Russian].
Sidaravičiene, N. 1996. Biostratigrafiya ordovikskikh ostrakod Litvy [Lithuanian Ordovician Ostracod Biostratigraphy]. Geological Institute, Vilnius, 81 pp. [in Lithuanian, with English summary].
Siveter, D. J. 2009. The Ordovician. In Ostracods in British Stratigraphy (Whittaker, J. E. W. & Hart, M. B., eds), pp. 15–44. The Micropalaeontological Society, Geological Society London.
https://doi.org/10.1144/TMS003.2
Tinn, O., Meidla, T. & Ainsaar, L. 2006. Arenig (Middle Ordovician) ostracods from Baltoscandia: Fauna, assemblages and biofacies. Palaeogeography, Palaeoclimatology, Palaeoecology, 241, 492–514.
https://doi.org/10.1016/j.palaeo.2006.05.002
Torsvik, H. & Cocks, L. R. M. 2013. Gondwana from top to base in space and time. Gondwana Research, 24, 999–1030.
https://doi.org/10.1016/j.gr.2013.06.012
Torsvik, T. & Cocks, L. 2017. Ordovician. In Earth History and Palaeogeography (Torsvik, T. & Cocks, L., eds), pp. 101–123. Cambridge University Press.
https://doi.org/10.1017/9781316225523.007
Trotter, J. A., Williams, I. S., Barnes, C. R., Lécuyer, C. & Nicoll, R. S. 2008. Did cooling oceans trigger Ordovician biodiversification? Evidence from conodont thermometry. Science, 321, 550–554.
https://doi.org/10.1126/science.1155814
Truuver, K. & Meidla, T. 2015. A Hirnantian deep-water refuge for warm-water ostracods in Baltoscandia. Geological Quarterly, 59, 738–749.
https://doi.org/10.7306/gq.1258
Truuver, K., Meidla, T., Ainsaar, L., Bergström, L. & Tinn, O. 2012. Stratigraphy of the Ordovician–Silurian boundary interval in Östergötland, Sweden, based on ostracod distribution and stable carbon isotopic data. GFF, 134, 295–308.
https://doi.org/10.1080/11035897.2012.762550
Turner, B. R., Armstrong, H. A. & Holt, P. 2011. Visions of ice sheets in the early Ordovician greenhouse world: Evidence from the Peninsula Formation, Cape Peninsula, South Africa. Sedimentary Geology, 236, 226–238.
https://doi.org/10.1016/j.sedgeo.2011.01.009
Vandenbroucke, T. R. A., Armstrong, H. A., Williams, M., Paris, F., Sabbe, K., Zalasiewicz, J. A., Nõlvak, 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, 249, 202–219.
https://doi.org/10.1016/j.palaeo.2009.11.026
Vandenbroucke T. R. A., Emsbo, P., Munnecke, A., Nuns, N., Duponchel, L., Lepot, K., Quijada, M., Paris, F., Servais, T. & Kiessling, W. 2015. Metal-induced malformations in early Palaeozoic plancton are harbingers of mass extinction. Nature Communications, 6, 7966.
https://doi.org/10.1038/ncomms8966
Vannier, J. M. C., Siveter, D. J. & Schallreuter, R. E. L. 1989. The composition and palaeogeographical significance of the Ordovician ostracode faunas of Southern Britain, Baltoscandia, and Ibero-Armorica. Palaeontology, 32, 163–222.
Wang, G., Zhan, R., Huang, B. & Percival, I. G. 2017. Coral faunal turnover through the Ordovician–Silurian transition in South China and its global implications for carbonate stratigraphy and macroevolution. Geological Magazine, 154, 829–836.
https://doi.org/10.1017/S0016756816000406
Wang, G., Zhan, R. & Percival, I. 2019. The end-Ordovician mass extinction: A single-pulse event? Earth-Science Reviews, 192, 15–33.
https://doi.org/10.1016/j.earscirev.2019.01.023
Wilde, P. & Berry, W. B. N. 1984. Destabilization of the oceanic density structure and its significance to marine extinction events. Palaeogeography, Palaeoclimatology, Palaeoecology, 48, 143–162.
https://doi.org/10.1016/0031-0182(84)90041-5
Williams, M., Stone, P., Siveter, D. J. & Taylor, P. 2001. Upper Ordovician ostracods from the Cautley district, northern England: Baltic and Laurentian affinities. Geological Magazine, 138, 589–607.
https://doi.org/10.1017/S0016756801005726
