Arthropod interactions with bennettitalean roots in a Triassic permineralized peat from Hopen, Svalbard Archipelago (Arctic) C. Strullu-Derrien a , S. McLoughlin b, ⁎, M. Philippe c , A. Mørk d, e , D.G. Strullu a, 1 a Université d'Angers, Laboratoire Mycorhizes, Faculté des Sciences, 2 boulevard Lavoisier, 49045 Angers Cedex, France. Current address: Université d'Angers, Laboratoire Bio-indicateurs Actuels et Fossiles (BIAF)—CNRS UMR 6112 LPGN, Faculté des Sciences, 2 boulevard Lavoisier, 49045 Angers Cedex, France b Naturhistoriska riksmuseet, Sektionen för paleobotanik, Box 50007, 104 05 Stockholm, Sweden c Laboratoire UMR CNRS 5276 et Université Claude Bernard Lyon 1, Campus de la Doua, Bâtiment DARWIN-A, 69622 Villeurbanne Cedex, France d SINTEF Petroleum Research, 7465 Trondheim, Norway e Norwegian University of Sciences and Technology, (NTNU), NO-7491, Trondheim, Norway abstract article info Article history: Received 15 February 2012 Received in revised form 30 May 2012 Accepted 8 June 2012 Available online 16 June 2012 Keywords: Triassic Bennettitales Oribatid mites Plant–arthropod interactions Palaeoecology Wood anatomy Silicified flora Svalbard Multiple thin-sections of a Late Triassic (Carnian) siliceous permineralized peat block likely derived from the De Geerdalen Formation on Hopen Island, Svalbard Archipelago, show a dense mass of roots preserving fine anatomical details of various stages of primary and secondary vascular tissue development. The presence of moderately defined rings with few latewood cells in the secondary xylem attests to growth in a seasonal en- vironment. The presence of mucilage bodies and nests of sclerotic cells in the cortical tissues of the roots and pith of subaerial stem fragments, together with scalariform pitting on radial tracheid walls and 2–12 simple pits per cross-field favor bennettitalean affinities for the roots. Evidence of a rich fauna of detritivores inhabiting the peat profile is represented in the form of extensive damage to cortical tissues of dead roots and abundant coprolites preserved both within chambers excavated in the plant tissues and in the peat matrix. Less common gall-like structures within the roots indicate the presence of parasitic organisms in the palaeo-peat ecosystem. © 2012 Elsevier B.V. All rights reserved. 1. Introduction Late Triassic high-latitude peat-forming ecosystems have been well documented from permineralized deposits in Antarctica (Taylor et al., 1989; Taylor and Taylor, 1990), but most other well-studied floras of this age, e.g., from South Africa (Anderson and Anderson, 1983, 1989, 2003), Argentina (Morel et al., 2003), Australia (Jones and de Jersey, 1947; Barone-Nugent et al., 2003); Iran-Afghanistan (Schweitzer and Kirchner, 2003), Kyrgyzstan (Dobruskina, 1995), Italy (Roghi et al., 2006), Austria (Pott et al., 2007, 2008a), southern Sweden (Nathorst, 1878; Lundblad, 1950; Pott and McLoughlin;, 2009) and East Greenland (Harris, 1932a, b, 1937) are known only from compression/impression floras that lack details of the cryptic components of the mire or flood- plain biota. In Europe, few studies have dealt with Late Triassic floras north of Skåne in southern Sweden (Dobruskina, 1994), hence interpre- tations of the vegetation of the northern margin of the Pangaea super- continent are based primarily on extrapolations from fossil floras of lower–middle palaeolatitudes, and from dispersed spore–pollen assem- blages (Smith, 1974; Bjærke and Manum, 1977; Dypvik et al., 1985). There have been few previous studies of Triassic macrofloras from the Svalbard archipelago. Vasilevskaya (1972, 1987) described a low- diversity flora containing peltasperms from Spitsbergen but these re- ports have not been widely circulated. Harland (1997) reported well- preserved floras including tree trunks of Late Triassic age from Kong Karls Land, but thorough systematic studies of these floras have not yet been undertaken. A revision of previous Triassic plant macrofossil collections from Svalbard held in Stockholm and St Petersburg is cur- rently underway (Pott, submitted). Selling (1944, 1945) briefly described the permineralized remains of a putative conifer (which he assigned to Protojuniperoxylon arcticum), and an isoetalean megaspore (which he referred to Triletes hopeniensis) from a block of permineralized peat collected in 1929 from the island of Hopen in the southern part of the Svalbard archi- pelago. Following critical remarks on the taxonomic appraisal of these Hopen remains by Kräusel (1949), and comments by Professor I.W. Bailey in personal correspondence, Selling (1951) later stated that attribution of the axes to Protojuniperoxylon was inappropriate and that the identity of these fossils remained to be settled by further study. The “Protojuniperoxylon” specimens studied by Selling (1944, 1945) are reinvestigated in this study and the anatomy and developmental Palaeogeography, Palaeoclimatology, Palaeoecology 348-349 (2012) 45–58 ⁎ Corresponding author. Tel.: + 46 8 5195 4142; fax: +46 8 5195 4221. E-mail addresses: christine.strullu-derrien@univ-angers.fr (C. Strullu-Derrien), steve.mcloughlin@nrm.se (S. McLoughlin), marc.philippe@univ-lyon1.fr (M. Philippe), atle.mork@sintef.no (A. Mørk). 1 Deceased October, 2011. 0031-0182/$ – see front matter © 2012 Elsevier B.V. All rights reserved. doi:10.1016/j.palaeo.2012.06.006 Contents lists available at SciVerse ScienceDirect Palaeogeography, Palaeoclimatology, Palaeoecology journal homepage: www.elsevier.com/locate/palaeo