Downloaded from http://sp.lyellcollection.org/ by guest on May 17, 2016 An introduction to the Mesozoic biotas of Scandinavia and its Arctic territories BENJAMIN P. KEAR1*, JOHAN LINDGREN2, JØRN H. HURUM3,4, JESPER MILA` N5,6 & VIVI VAJDA2,7 1Museum of Evolution, Uppsala University, Norbyva¨gen 16, 752 36 Uppsala, Sweden 2Department of Geology, Lund University, So¨lvegatan 12, 223 62 Lund, Sweden 3Natural History Museum, University of Oslo, Postboks 1172, Blindern, 0318 Oslo, Norway 4The University Centre in Svalbard, UNIS, Postboks 156, 9171 Longyearbyen, Norway 5Geomuseum Faxe/Østsjællands Museum, Østervej 2, DK-3640 Faxe, Denmark 6Natural History Museum of Denmark, Øster Voldgade 5-7, DK-1350 Copenhagen K, Denmark 7Department of Palaeobiology, Swedish Museum of Natural History, Postboks 50007, SE-104 05 Stockholm, Sweden *Corresponding author (e-mail: [email protected]) Abstract: The Mesozoic biotas of Scandinavia have been studied for nearly two centuries. How- ever, the last 15 years have witnessed an explosive advance in research, most notably on the richly fossiliferous Triassic (Olenekian–Carnian) and Jurassic (Tithonian) Lagersta¨tten of the Norwe- gian Arctic Svalbard archipelago, Late Cretaceous (Campanian) Kristianstad Basin and Vomb Trough of Ska˚ne in southern Sweden, and the UNESCO heritage site at Stevns Klint in Denmark – the latter constituting one of the most complete Cretaceous–Palaeogene (Maastrichtian–Danian) boundary sections known globally. Other internationally significant deposits include earliest (Induan) and latest Triassic (Norian–Rhaetian) strata from the Danish autonomous territory of Greenland, and the Early Jurassic (Sinemurian–Pliensbachian) to Early Cretaceous (Berriasian) rocks of southern Sweden and the Danish Baltic island of Bornholm, respectively. Marine palaeo- communities are especially well documented, and comprise prolific benthic macroinvertebrates, together with pelagic cephalopods, chondrichthyans, actinopterygians and aquatic amniotes (ich- thyopterygians, sauropterygians and mosasauroids). Terrestrial plant remains (lycophytes, spheno- phytes, ferns, pteridosperms, cycadophytes, bennettitaleans and ginkgoes), including exceptionally well-preserved carbonized flowers, are also world famous, and are occasionally associated with faunal traces such as temnospondyl amphibian bones and dinosaurian footprints. While this collec- tive documented record is substantial, much still awaits discovery. Thus, Scandinavia and its Arctic territories represent some of the most exciting prospects for future insights into the spectacular his- tory of Mesozoic life and environments. Gold Open Access: This article is published under the terms of the CC-BY 3.0 license. The Mesozoic fossil record of Scandinavia and its of palaeontological research in Europe (Rudwick Arctic territories of Greenland and Svalbard span 2008; Evans 2010), and yet many key biotas and the dawn of the Triassic some 252 myr ago (Wordie bioevents from this continent remain comparatively Creek Formation, East Greenland: Nielsen 1935; underexplored. Scandinavia and its Arctic territories Bendix-Almgreen 1976; Looy et al. 2001; Stem- are therefore extremely important because they merik et al. 2001; Bjerager et al. 2006) through to encompass not only a Boreal mid–high palaeolati- the terminal Cretaceous–Palaeogene boundary tude setting (Surlyk 1990; Ditchfield 1997), but 66 myr ago (Møns Klint Formation, Denmark: have also witnessed a burgeoning of novel discover- Damholt & Surlyk 2012; Surlyk et al. 2013; Adolfs- ies that reveal significant insights into the global sen & Ward 2014; Hansen & Surlyk 2014). This spectrum of Mesozoic organisms, ecosystems and interval is marked by the nascence of modern environments. faunal and floral biodiversity, and culminated in This Special Publication aims to encapsulate one of the most cataclysmic extinction events in these latest palaeontological advances, and aug- Earth history. Much of our knowledge about the ments them with topical synopses from leading spe- Mesozoic world has derived from the long tradition cialists in the field. Our introduction is intended to From:Kear, B. P., Lindgren, J., Hurum, J. H., Mila`n,J.&Vajda, V. (eds) 2016. Mesozoic Biotas of Scandinavia and its Arctic Territories. Geological Society, London, Special Publications, 434, 1–14. First published online April 20, 2016, http://doi.org/10.1144/SP434.18 # 2016 The Author(s). Published by The Geological Society of London. Publishing disclaimer: www.geolsoc.org.uk/pub_ethics Downloaded from http://sp.lyellcollection.org/ by guest on May 17, 2016 2 B. P. KEAR ET AL. provide additional contextual background, and, in 2015 and references therein), and coincide with particular, emphasizes the broad trends in floral lush vegetation comprising ginkgoes, cycads and successions and the distribution of faunal finds. bennettites, lycophytes, sphenophytes, and ferns Together, these highlight Scandinavia and its Arctic (Vajda et al. 2013). Fossilized fungi and bacterial territories as a regional centre for Mesozoic biotic traces have also been reported from Hopen Island radiations, and a spectacular area for future field in the Svalbard archipelago (McLoughlin & exploration with landmark research potential. Strullu-Derrien 2015). A bone fragment of a Late Triassic sauropodomorph was also recovered from Institutional abbreviations a drill core in the North Sea 2256 m below the seabed (Hurum et al. 2006a). LO, Department of Geology, Lund University, Earliest Triassic (Induan–Olenekian) marine Lund, Sweden; MGUH, Natural History Museum ecosystems are recognized from the Vardebukta of Denmark, Copenhagen, Denmark; OESM, Østs- Formation on Svalbard (Vigran et al. 2014), and jællands Museum, Store Heddinge, Denmark; most prolifically from the world-famous Wordie PMO, University of Oslo Natural History Museum Creek Formation in East Greenland (Fig. 1a–e). (Palaeontological Collection), Oslo, Norway; PMU, These deposits incorporate bivalves, gastropods Palaeontology Collection, Museum of Evolution, and ammonoids, as well as actinopterygian and coe- Uppsala University, Uppsala, Sweden. lacanth fishes (Spath 1932; Nielsen 1942, 1949; Donovan 1964) that span the Permian–Triassic boundary (Twitchett et al. 2001; Bjerager et al. A synthesis of Scandinavian Mesozoic biotas 2006). Potentially anadromous Early Triassic tem- The Triassic nospondyls (primarily tematosaurids, rhytidostians and capitosaurians) have also been described, with The long history of Scandinavia’s terrestrial biotas approximately equivalent occurrences found on is charted through the palynological record, which Spitsbergen and other islands in Svalbard (Sa¨ve- manifests liverworts as the seminal colonizers of So¨derbergh 1936; Cox & Smith 1973; reviewed by continental ecosystems in the early Palaeozoic Kear et al. 2015): these are associated with actino- (Late Ordovician) of southern Sweden (Badawy pterygian fishes (Fig. 1f) and hybodontiform sharks et al. 2014). Increasing abundance and diversity of (Stensio¨ 1921, 1925; Blazejowski et al. 2013). bryophytes and vascular plants occurred throughout Globally renowned Triassic marine amniote the Silurian and Devonian in Ska˚ne (Mehlqvist et al. fossils were recovered from Spitsbergen during 2015) and Gotland (Hagstro¨m 1997), with the gene- the Nordenskio¨ld expeditions of 1864 and 1868 sis of characteristic Mesozoic floras around the (Hulke 1873). More complete material was subse- Permian–Triassic boundary in Greenland, Svalbard quently collected by Swedish scientists in 1908 and the Oslo Rift: these collectively indicate turn- and 1909 (Wiman 1910, 1916a, b, 1928, 1933), over of regional biomes coincident with increasing and constitutes a diverse assemblage of ichthyop- aridity (Bercovici et al. 2015). The Permian–Trias- terygians (Fig. 1g), including the phylogenetically sic extinction event is otherwise expressed by the important basal taxon Grippia longirostris (Max- disappearance of dominant hygrophilous Cordaites well & Kear 2013). Isolated pistosaurid saurop- (which equate to gigantopterids in Cathaysia and terygian remains have also been discovered (Kear glossopterids in Gondwana) and their replacement & Maxwell 2013), and Hurum et al. (2014) docu- by emergent seed plants (Anderson et al. 1999; mented Triassic ichthyosaurian material from McLoughlin 2011). Edgeøya (Vigran et al. 2014). The classic vertebrate The coeval chronicle of Triassic terrestrial successions of Wiman (1910) are, however, still faunas is not well represented until the Norian– used to subdivide the horizons on Spitsbergen Rhaetian of the Fleming Fjord Formation in Jame- (see Maxwell & Kear 2013): the lithostratigraphi- son Land, East Greenland (Klein et al. 2015; cal work of Mørk et al. (1999), equating the Mila`n et al. 2015). Here, body fossils and foot- actinopterygian-andtemnospondyl-dominated‘Fish prints evidence various dinosaurian taxa, especially Niveau’ to the lower Olenekian Lusitaniadalen sauropodomorphs, together with plagiosaurid and Member of the Vikinghøgda Formation; the ‘Grip- capitosaurian temnospondyl amphibians, rare rham- pia Niveau’ and ‘Lower Saurian Niveau’ – both phorhynchoid pterosaurians, and early mammali- representing sequential components of the Late forms (e.g. Bendix-Almgreen 1976; Jenkins et al. Olenekian–Anisian Vendomdalen Member of the 1994; Mila`n et al. 2012a; Sulej et al. 2014; Clem- Vikinghøgda Formation; and derived mixosaurid mensen et al. 2015; Hansen et al. 2015; Klein and shastasaurid ichthyosaurians from