The Vertebrate-Bearing Late Triassic Fleming Fjord Formation of Central East Greenland Revisited: Stratigraphy, Palaeoclimate and New Palaeontological Data
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Downloaded from http://sp.lyellcollection.org/ at Orta Dogu Teknik Universitesi on December 17, 2015 The vertebrate-bearing Late Triassic Fleming Fjord Formation of central East Greenland revisited: stratigraphy, palaeoclimate and new palaeontological data LARS B. CLEMMENSEN1, JESPER MILA` N2,3*, JAN SCHULZ ADOLFSSEN2, ELIZA JARL ESTRUP4, NICOLAI FROBØSE1, NICOLE KLEIN5, OCTA´ VIO MATEUS6,7 & OLIVER WINGS8,9 1Department of Geosciences and Natural Resource Management, University of Copenhagen, Øster Voldgade 10, DK-1350 Copenhagen K, Denmark 2Geomuseum Faxe/Østsjællands Museum, Østervej 2, DK-4640 Faxe, Denmark 3Natural History Museum of Denmark, University of Copenhagen, Øster Voldgade 5-7, DK-1350 Copenhagen K, Denmark 4Geocenter Møns Klint, Stenga˚rdsvej 8, DK-4751 Borre, Denmark 5Staatliches Museum fu¨r Naturkunde Stuttgart, Rosenstein 1, 70191 Stuttgart, Germany 6Department of Earth Sciences, GeoBioTec, Faculdade de Cieˆncias e Tecnologia, FCT, Universidade Nova de Lisboa, 2829-516 Caparica, Portugal 7Museu da Lourin˜ha, Rua Joa˜o Luis de Moura 95, 2530-158 Lourinha˜, Portugal 8Niedersa¨chsisches Landesmuseum Hannover, Willy-Brandt-Allee 5, 30169 Hannover, Germany 9Museum fu¨r Naturkunde Berlin, Invalidenstraße 43, D-10115 Berlin, Germany *Corresponding author (e-mail: [email protected]) Abstract: In Late Triassic (Norian–Rhaetian) times, the Jameson Land Basin lay at 408 N on the northern part of the supercontinent Pangaea. This position placed the basin in a transition zone between the relatively dry interior of the supercontinent and its more humid periphery. Sedimen- tation in the Jameson Land Basin took place in a lake–mudflat system and was controlled by orbi- tally forced variations in precipitation. Vertebrate fossils have consistently been found in these lake deposits (Fleming Fjord Formation), and include fishes, dinosaurs, amphibians, turtles, aetosaurs and pterosaurs. Furthermore, the fauna includes mammaliaform teeth and skeletal material. New vertebrate fossils were found during a joint vertebrate palaeontological and sedimentological expe- dition to Jameson Land in 2012. These new finds include phytosaurs, a second stem testudinatan specimen and new material of sauropodomorph dinosaurs, including osteologically immature indi- viduals. Phytosaurs are a group of predators common in the Late Triassic, but previously unre- ported from Greenland. The finding includes well-preserved partial skeletons that show the occurrence of four individuals of three size classes. The new finds support a late Norian–early Rhaetian age for the Fleming Fjord Formation, and add new information on the palaeogeographical and palaeolatitudinal distribution of Late Triassic faunal provinces. Late Triassic (Norian–Rhaetian) lake sediments of The vertebrate fauna of the Fleming Fjord For- the Fleming Fjord Formation are very well exposed mation is both abundant and diverse, and includes along the eastern margin of the Jameson Land Basin fishes, dinosaurs, amphibians, turtles, aetosaurs and in East Greenland (Fig. 1). These lake deposits have pterosaurs (Jenkins et al. 1994; Sulej et al. 2014). been the subject of detailed stratigraphical, sedi- Furthermore, the fauna includes both teeth and skel- mentological and palaeontological studies since the etal elements of mammaliforms (Jenkins et al. 1994, late 1970s (e.g. Clemmensen 1980a, b; Jenkins et al. 1997), such as Haramiyavia clemmenseni, Brachy- 1994; Kent & Clemmensen, 1996; Clemmensen zostrodon and Kuehneotherium. The association of et al. 1998; Mila`n et al. 2004). several vertebrate groups is shared with well-known From:Kear, B. P., Lindgren, J., Hurum, J. H., Mila`n,J.&Vajda, V. (eds) Mesozoic Biotas of Scandinavia and its Arctic Territories. Geological Society, London, Special Publications, 434, http://doi.org/10.1144/SP434.3 # 2015 The Author(s). Published by The Geological Society of London. All rights reserved. For permissions: http://www.geolsoc.org.uk/permissions. Publishing disclaimer: www.geolsoc.org.uk/pub_ethics Downloaded from http://sp.lyellcollection.org/ at Orta Dogu Teknik Universitesi on December 17, 2015 L. B. CLEMMENSEN ET AL. Fig. 1. Location map of East Greenland showing the Mesozoic deposits in the Jameson Land Basin. Small inset: Greenland. Large inset shows a close-up of the eastern part of the basin near Carlsberg Fjord, and the two localities with Upper Triassic sediments at Lepidopteriselv and Wood Bjerg–Macknight Bjerg. Figure modified from Stemmerik et al. (1997). European Norian faunas, and the Greenland mate- The published reptile taxa from the Late Triassic rial adds new information to our understanding of of Greenland are cf. Proganochelys (Testudinata), the palaeogeographical distribution of Late Triassic Aetosaurus ferratus and Paratypothorax andressi fauna provinces. The vertebrate assemblage con- (Aetosauria: Stagonolepididae), Plateosaurus eng- strains the Jameson Land fauna in the Norian (Jen- elhardti (Dinosauria: Sauropodomorpha: Plateo- kins et al. 1994). sauridae), Theropoda? indet., and Eudimorphodon Downloaded from http://sp.lyellcollection.org/ at Orta Dogu Teknik Universitesi on December 17, 2015 LATE TRIASSIC VERTEBRATE FAUNA, GREENLAND cromptonellus (Pterosauria: Eudimorphodontidae: underwent regression and continental emergence Eudimorphodontinae). This list is largely based later in the early Triassic (Clemmensen 1980a, b; on the brief descriptions by Jenkins et al. (1994), Nøttvedt et al. 2008). Continental sediments com- except for Eudimorphodon cromptonellus, which prised alluvial fan, floodplain, aeolian dune, saline was the focus of a later monographic work (Jenkins lake and freshwater lake deposits (Clemmensen et al. 2001). Therapsids are represented by the 1980a; Clemmensen et al. 1998). The freshwater cynodont Miltredon cromptoni (Shapiro & Jenkins lake deposits in the uppermost part of the Triassic 2001), and amphibians represented by Gerrotho- succession (the Fleming Fjord Formation) are par- rax pulcherrimus and Cylcotosaurus cf. posthumus ticular well exposed in steep cliff sides facing the (Jenkins et al. 1994, 2008). Classification of the Carlsberg Fjord (Fig. 2). remains attributed to theropods is not supported by any clear diagnostic theropodan feature and might alternatively be phytosaurian in origin. Methods New data from an expedition in 2012 (briefly reported in Mila`n et al. 2012) shows the presence The area around Lepidopteriselv (Fig. 1; Jenkins of phytosaurs, a second testudinatan specimen and et al. 1994, area II) was intensively prospected, new material of sauropodomorph dinosaurs. Phyto- revealing many isolated bones, bone fragments and saurs are an archosaurian group of top predators tracks; all suitable material on the surface was col- common in the Late Triassic, but previously unre- lected. After several bone fragments were found at ported from Greenland. The finds include well- the Plateosaurus site described by Jenkins et al. preserved partial skeletons that show the occurrence (1994), two trenches, each several metres long and of four individuals of three size classes (Mateus about 50 cm deep, were excavated in the unsuccess- et al. 2014). ful search for more articulated bones. Work focused The aims of this paper are to redescribe the strati- during the first half of the expedition on several graphical, palaeoenvironmental and palaeoclimatic dinosaur tracksites and a new site on the mountain setting of the vertebrate-bearing lacustrine succes- slopes east of the camp, which was named the ‘Phy- sion, to provide a first description and classification tosaur Bone Bed’ (718 15.584′ N, 228 31.785′ W). A of the new vertebrate finds from the Late Triassic of few teeth and bones were found on the surface near a East Greenland, and to briefly discuss the palaeo- small ledge, and cleaning of the surface over an area geographical and chronological implications of the of several square metres was commenced in order to vertebrate assemblage. identify the bone-bearing layers. Prospecting, sur- face collection and excavation was continued at Wood Bjerg and Macknight Bjerg (Fig. 1) close to Geological setting area V of Jenkins et al. (1994). Excavation here focused at the old Jenkins quarry (718 22.262′ N, During Triassic times, East Greenland was located 228 33.381′ W), which was named ‘Iron Cake’ due at the northern rim of the Pangaean supercontinent to the iron-rich matrix of the bone-bearing sediment. and bounded to the north by the Boreal Sea The concretion-like iron-rich matrix was impossible (Nøttvedt et al. 2008). Triassic sediments are well to remove via field preparation and, hence, entire exposed in the Jameson Land Basin, which is blocks of sediment were excavated. located in central East Greenland at about 718 Nat Sediment grain size, depositional structures, bed the present-day land areas of Jameson Land and geometry, and the relationship to the over- and Scoresby Land (Fig. 1). The basin was situated at underlying facies were investigated for each bone- the southern end of the East Greenland rift system, and track-bearing layer. Special attention was given which formed part of a larger rift complex separat- to beds with wave ripples as they contain informa- ing Greenland from Norway prior to the opening tion on the palaeoclimatic events that brought rain of the Atlantic (Ziegler 1988). It was bounded to to the basin (cf. Clemmensen et al. 1998). Sedimen- the west by a major north–south-trending fault and tological logs on the scale of 1:10 were measured in to the east by the Liverpool Land structural high.