Journal of Paleontology, 92(5), 2018, p. 838–849 Copyright © 2018, The Paleontological Society 0022-3360/15/0088-0906 doi: 10.1017/jpa.2018.11
A new genus of eurypterid (Chelicerata, Eurypterida) from the Upper Devonian salt deposits of Belarus
Dmitry P. Plax,1 James C. Lamsdell,2 Matthew B. Vrazo,3 and Dmitry V. Barbikov4
1Belarusian National Technical University, Nezavisimosti Avenue, 65, 220013, Minsk, Belarus ⟨
agnatha@mail.ru⟩ 2Department of Geology and Geography, West Virginia University, 98 Beechurst Avenue, Brooks Hall, Morgantown, West Virginia 26506, USA
⟨
james.lamsdell@
mail.wvu.edu⟩ 3Department of Paleobiology, National Museum of Natural History, The Smithsonian Institution, Washington, DC 20013-7012, USA
⟨
vrazom@si.edu⟩ 4Republican Unitary Enterprise Production Amalgamation ‘Belaruskali,’ 5 Korzha Street, 223710, Soligorsk, Belarus ⟨
barbikov@kali.by⟩
Abstract.—We describe a new stylonurid eurypterid from the evaporitic potassium-salt deposits of the Upper Devo- nian (Famennian) Soligorsk Formation in the Pripyat Trough of Belarus. All specimens are assigned to Soli- gorskopterus tchepeliensis new genus new species, which represents the first formally described eurypterid species from Belarus. The occurrence of well-preserved eurypterids in these unusual evaporite deposits is most likely due to transport from freshwater stream habitats into a hypersaline setting following death. Soligorskopterus tchepeliensis n. gen. n. sp. appears to be intermediate between the traditionally considered parastylonurids and stylonurids and thus extends our understanding of stylonurid evolution in the mid-Paleozoic. Soligorskopterus n. gen. extends the occur- rence of Famennian eurypterids into eastern Laurussia and the Stylonuridae into the Upper Devonian, and this taxon could be part of a global eurypterid habitat shift that took place in the Late Devonian.
UUID:
http://zoobank.org/466b0195-6199-495b-9270-6f032e2d7493 Introduction
Eurypterids (Arthropoda, Chelicerata) are extinct aquatic chelicerates that achieved widespread geographic distribution between their origination in the Middle Ordovician and extinction at the end of the Permian (Tetlie, 2007; Lamsdell et al., 2015). Within the order are significant differences in the extent to which some taxa were dispersed, and this could be a reflection of relative swimming abilities, morphospace occu- pation, and the eurypterid marine–freshwater environmental transition that took place in the mid-Paleozoic (Lamsdell and Braddy, 2010; Lamsdell and Selden, 2017). For example, in the transitional Silurian–Devonian, walking-legged stylonur- ines were confined to the paleocontinents that make up Laur- ussia (Tetlie, 2007); most stylonurids known from this time occur in the USA and Scotland (eastern Laurentia), with only a few known from mainland Europe. A few Silurian–Devo- nian-age swimming eurypterine taxa are known from eastern Europe, the Baltics, Ukraine, and Russia (Plotnick, 1983, 1999; Tetlie, 2007, and references therein), but stylonurines in this region are rare, having only been found (but not named) in Belarus (Plax et al., 2009; Obukhovskaya et al., 2010; Plax and Barbikov, 2012, 2013). Over the last 40 years, several stylonurine specimens have
been obtained during mining excavations in the Belarusian Starobin potassium-salt evaporite basin, all from within the Osovets Beds of the Upper Devonian Soligorsk Formation (Plax
et al., 2009; Fig. 1). These specimens are exceptionally pre- served as carbonized, nearly fully articulated bodies (to 34cm in length) and isolated appendages. Aside from eurypterids, the only other organismal remains known from these beds are rare terrestrial plants and local miospores. Although the occurrence and general morphology of the eurypterids in these potassium- salt deposits has been documented previously (Plax et al., 2009; Obukhovskaya et al., 2010; Plax and Barbikov, 2012, 2013), they have not yet been described within a detailed morpholo- gical or systematic context. In this paper, we present a comprehensive morphological
description of these stylonurine eurypterids and describe their systematic and phylogenetic affiliation. All specimens are assigned to Soligorskopterus tchepeliensis new genus new species, the first eurypterid taxon formally described from Belarus. We consider the paleoecology and unusual preserva- tion of S. tchepeliensis n. gen. n. sp. in this evaporitic lithofacies, and the paleogeography of stylonurids in the Late Devonian. The exceptional preservation of eurypterid material from this region provides a unique perspective on global eurypterid dis- tributions at a critical time in their history.
Geological setting and stratigraphy
All specimens described herein were found in the Upper Devo- nian Soligorsk Formation (middle Famennian; Streshin regional stage; Osovets Beds) in the northwestern edge of the Pripyat
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