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Studies of marine microbioerosion in polar environments are scarce. They include our recent investigations of bioerosion traces preserved in sessile balanid skeletons from the Arctic Svalbard archipelago and the Antarctic Ross Sea. Here, we present results from a third study site, Frobisher Bay, in the eastern Canadian Arctic, together with a synthesis of our current knowledge of polar bioerosion in both hemispheres. Barnacles from 62 to 94 m water depth in Frobisher Bay were prepared using the cast-embedding technique to enable visualization of microboring traces by scanning electron microscopy. In total, six ichnotaxa of traces produced by organotrophic bioeroders were found. All recorded ichnotaxa were also present in Mosselbukta, Svalbard, and most in the Ross Sea. Frobisher Bay contrasts with Mosselbukta in that it is a siliciclastic-dominated environment and shows a lower ichnodiversity, which may be accounted for by the limited bathymetrical range and a high turbidity and sedimentation rate. We evaluate potential key ichnotaxa for the cold-temperate and polar regions, of which the most suitable are Flagrichnus baiulus and Saccomorpha guttulata, and propose adapted index ichnocoenoses for the interpretation of palaeobathymetry accordingly. Together, the three studies allow us to make provisional considerations about the biogeographical distribution of polar microbioerosion traces reflecting the ecophysiological limits of their makers.

Trace fossils provide detailed palaeoenvironmental and palaeoecological information of both ancient and modern sedimentary systems. During middle Miocene times the Aures Massif located in the northeastern part of Algeria, was affected by, at least, one marine transgression. The latter led to the installation of a carbonate platform, which is placed, for the first time, in a Mediterranean context. In the Rhassira basin, the Middle Miocene marine succession is characterised by carbonate platform deposits dominated by rhodolith beds, typical of those known throughout the Mediterranean area. This succession can be divided into many units separated by discontinuities interpreted here as omission surfaces. The Djebel Arhane section shows two omission surfaces characterised by a pre-omission suite (firmground) represented by Balanoglossites burrows for the first surface and Gastrochaenolites ornatus burrows/borings for the second one, and an omission suite (hardground) as evidenced by the bioerosive structures Trypanites and Caulostrepsis , in both surfaces, respectively. Gastrochaenolites ornatus traces were formed and preserved in firm, compact, semi-lithified and fine-grained substrates (firm- to hardground), indicating the Glossifungites ichnofacies. They show bioglyphs which have been formed during contraction of the posterior adductor muscles. These suggest that their tracemakers were represented by suspension-feeding bivalves, most probably Pholadidae or Mytilidae, which rotated during penetration. The fill of these traces is composed of marine deposits related to a transgressive lag. The omission suite is divided into two ichnocoenoses: (i) pre-lithification burrows/borings, and (ii) post-lithification borings. This is the first report of the ichnotaxon G. ornatus from Algeria. [ABSTRACT FROM AUTHOR]

Studies of marine microbioerosion in polar environments are scarce. They include our recent investigations of bioerosion traces preserved in sessile balanid skeletons from the Arctic Svalbard archipelago and the Antarctic Ross Sea. Here, we present results from a third study site, Frobisher Bay, in the eastern Canadian Arctic, together with a synthesis of our current knowledge of polar bioerosion in both hemispheres. Barnacles from 62 to 94 m water depth in Frobisher Bay were prepared using the cast-embedding technique to enable visualization of microboring traces by scanning electron microscopy. In total, six ichnotaxa of traces produced by organotrophic bioeroders were found. All recorded ichnotaxa were also present in Mosselbukta, Svalbard, and most in the Ross Sea. Frobisher Bay contrasts with Mosselbukta in that it is a siliciclastic-dominated environment and shows a lower ichnodiversity, which may be accounted for by the limited bathymetrical range and a high turbidity and sedimentation rate. We evaluate potential key ichnotaxa for the cold-temperate and polar regions, of which the most suitable are Flagrichnus baiulus and Saccomorpha guttulata, and propose adapted index ichnocoenoses for the interpretation of palaeobathymetry accordingly. Together, the three studies allow us to make provisional considerations about the biogeographical distribution of polar microbioerosion traces reflecting the ecophysiological limits of their makers. [ABSTRACT FROM AUTHOR]

The palaeoenvironmental significance of trace fossil assemblages in the flysch deposits of the Upper Cretaceous of the Sistan ocean – the Sefidabeh basin in the Sistan Suture Zone SSZ in Eastern Iran – has been assessed for the first time. The Sefidabeh basin of turbidite origin consists of 10 sedimentary facies, which can be grouped into 3 facies associations (FA) representing submarine channel-related facies associations (FA1), lobe-related facies associations (FA2), distal fan-basin floor facies associations of a deep-water turbidite system (FA3). Thirty three ichnogenera, with many ichnospecies, have been identified in this deep sea succession: Alcyonidiopsis , Arthrophycus , Asterostoma , Belorhaphe , Bergaueria , Cardioichnus , Chondrites , Cosmorhaphe , Desmograpton , Gyrophyllites , Halopoa , Helminthopsis , Helminthorhaphe , Laevicyclus , Lophoctenium , Mammilichnis , Megagrapton , Multina , Nereites , Ophiomorpha , Palaeophycus , Planolites , Phycodes , Phycosiphon , Paleodictyon , Rutichnus , Scolicia , ?Strobilorhaphe , Taenidium , Teichichnus , Thalassinoides , Zoophycos and Urohelminthoida . Their distribution is clearly linked with lithofacies and depositional palaeoenvironments. Changes in trace fossil assemblages and ichnocoenoses follow different environments of the turbidity system of the submarine channel to fan system of the Sefidabeh basin and are associated with variations in environmental controlling factors. Environmental controlling factors including hydrodynamic regime, oxygen level, organic content and sedimentation rates. Ten ichnocoenoses were recognized in the facies associations of the deep-sea fan system of this study. Taking into consideration the diversity, bioturbation level, and colonization order of bioturbated beds and the obvious deepening of the deep-sea depositional system from inner to outer parts of the succession, ichnocoenoses can express a bathymetric trend from shallower to deeper parts, and from higher-to-lower hydrodynamic condition of deep-sea fan systems of the Sefidabeh basin. This study reveals important sedimentological and ichnological features of turbiditic systems in deep sea settings of Iran and permits the development of predictive models for the palaeoenvironmental significance of trace fossil assemblages that can be readily translated to analogous depositional systems in the surface/subsurface. [ABSTRACT FROM AUTHOR]

An integrated taphonomical, ichnological and sedimentological analysis has been carried out on the Albian deposits of the Sierra Helada section (Province of Alicante, southeastern Spain). This allowed recognition and detailed characterization of the shallowing- and coarsening-upward sequences present in these deposits. Twenty sequences were detected throughout the section. They contain the following, from bottom to top: (1) the bottom of the sequence characterized by very fine-grained marls rich in echinoid tests and echinoid trace fossils with very little evidence of physical reworking—it records a distal platform, low-energy environment; (2) marls interbedded with fine-grained calcarenites, rich in large Thalassinoides and slightly reworked echinoid tests, with common bioclast-armored tubes ( Ereipichnus geladensis ), recording low-energy background conditions but increasing energy of the sedimentary events, (3) coarse-grained calcarenites rich in different types of small to large Thalassinoides and E. geladensis horizons, showing the intense and frequent action of storms and directed currents on the seafloor, and (4) coarse-grained, cross-bedded calcarenites, rich in Ophiomorpha nodosa , deposited under high-energy background conditions in the shallowest part of the sequence, recording the presence of shifting dunes in the inner platform. Occasionally, also the record of a rapid transgression has been pointed out through the presence of condensed tapho- and sedimentary facies and mixed ichnocoenoses at the top of the sequence just after an erosive surface. The defined ichnoceonoses and their distribution throughout the sequence reflect the shifting from a distal expression of the Cruziana Ichnofacies to the shallower archetypal Cruziana Ichnofacies and finally to the high-energy, shallow-water Skolithos Ichnofacies. The distribution of taphofacies and ichnocoenoses and development of the sequences all through the section show a general transgression followed by a regressive phase, which fit with the third-order curves described for the area on the basis of pure sedimentological analysis in previous studies ( Castro et al., 2008 ). [ABSTRACT FROM AUTHOR]

Jamaica has the most diverse record of Cenozoic trace fossils of any of the Antillean islands, with over 100 ichnospecies divided among more than 50 ichnogenera. Trace fossils have been identified from both shallow- and deep-water deposits in most major lithostratigraphic divisions, namely the Paleogene Richmond Formation (Wagwater Group), the mid-Cenozoic White Limestone Group and the Neogene Coastal Group. Persistent ichnogenera in these palaeoenvironments include the burrows Palaeophycus Hall, Planolites Nicholson, Taenidium Heer and Thalassinoides Ehrenberg (deeper water), and the borings/microborings Entobia Bronn, Gastrochaenolites Leymerie and Oichnus Bromley (shallow water). Differences in diversity of ichnotaxa between formations can, in part, be due to differences in lithofacies and absolute water depth. This is recognized in the differences in deeper water lithofacies between the Richmond Formation (siliciclastic turbidites), White Limestone Group (chalks), Lower Coastal Group (submarine mass flow deposits) and Upper Coastal Group (deep fore reef). Intervals and lithofacies still awaiting detailed investigation include Pleistocene red beds and fore-reef, Pliocene raised reef and shallow siliciclastic shelf, and most of the varied palaeoenvironments represented by the Eocene Yellow Limestone Group. Only crocodile coprolites (Eocene) are attributable to vertebrates; algal microborings apart, the only plant traces are Pleistocene root casts that await description. Copyright © 2014 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

Four vertebrate tracksites from the Middle Jurassic and Upper Cretaceous in the Tataouine basin of southern Tunisia are described. Approximately 130 tridactyl footprints distributed over an area of 200 square meters, preserved on Callovian beds exposed at the Beni Ghedir site, represent the oldest evidence of a dinosaur fauna in Tunisia. In addition, three tracksites—Chenini, Ksar Ayaat, and Jebel Boulouha—have been discovered in the Cretaceous beds of the upper Continental Intercalaire, previously considered as a strictly marine depositional sequence. In addition to dinosaur tracks, the Chenini tracksite (late Albian) includes poorly preserved crocodilian tracks, and footprints assigned to a pleurodiran turtle have been recovered at the Ksar Ayaat locality (early Cenomanian). The Jebel Boulouha tracksite is dominated by well-preserved tridactyl tracks referred to small-sized theropods. Depositional settings of each tracksite have been defined on stratigraphic and sedimentologic data, and tracks were ascribed to different ichnocoenoses in relation to their paleoenvironments. This new and differentiated track record gives important information on how the fossil vertebrate fauna changed in southern Tunisia during mid-Jurassic to mid-Cretaceous times. These data provide a unique and useful census of tetrapod associations along the southern margin of the peri-Mediterranean area. [ABSTRACT FROM AUTHOR]

The track rich Cretaceous Jindong Formation is famous for abundant tetrapod track assemblages, which occur at multiple, closely-spaced stratigraphic levels in the Gyeongsang Basin lake deposits of South Korea. However, until now no fish traces or fish body fossils had been reported. Thus, the discovery of three Undichna ichnospecies (U. simplicitas , U. bina , and U. britannica) provide the first direct evidence of fish in the basin. Paired in-phase traces vary in width and indicate a range of fish sizes among the tracemakers. Undichna assemblages represent a shallow lacustrine Undichna ichnocoenosis. Bird tracks (Ignotornis) registered on the same surface represent the superposition of a shorebird ichnocoenosis. Dinosaur tracks (Brontopodus and Caririchnium) associated with surfaces only ∼1 m below the bird and fish traces, represent additional large tetrapod ichnocoenoses, and demonstrate multiple, superimposed ichnocoenoses, interpenetrating localized sedimentary successions which are little separated in space or time. The Undichna and shorebird, ichnocoenoses are considered, in schema followed here, as representative of higher-level 'archetypal' Charachichnos and Grallator ichnofacies respectively. However, it is not clear whether a third ichnocoenosis and ichnofacies is represented by the Brontopodus and Caririchnium assemblages or the extent to which the overprinting of different ichnofaunas in localized areas always allows for the unambiguous application of ichnocoenois and ichnofacies schema. [ABSTRACT FROM AUTHOR]

In the cold-temperate setting of the Swedish Kosterfjord, a 2-year experiment was launched in order to assess bioerosion rates and to investigate the endolithic borer communities in relation to light availability (relative bathymetry), hydrography and exposure time. The inventory of microendolithic traces, studied by SEM analysis of epoxy resin casts of planted bivalve shells, yields diverse ichnocoenoses comprising a total of 21 traces produced by boring cyanobacteria (7), chlorophytes (4), fungi (6) and traces of uncertain affinity (4). The link between the endoliths (biotaxa) and the traces they leave (ichnotaxa) is evaluated by the study of the boring organisms in situ by transmission light microscopy of planted Iceland spar and bivalve shells. Additionally, the activity of various macroborers (foraminiferans, polychaetes, echinoids, gastropods and sponges) is documented, adding to a distinct diversity maximum at 7 m water depth. A highly condensed photic zonation, due to the high latitude (59°) and eutrophic conditions, is recorded by the measurement of the Photosynthetically Active Radiation (PAR) and is confirmed by the bathymetric range of the photic related ichnocoenoses. At 1 m water depth, a mature shallow euphotic ichnocoenosis dominated by cyanobacteria and at 7 m, a deep euphotic ichnocoenosis dominated by chlorophytes, respectively, is developed after as little as 12 months exposure. With the vanishing light availability from 15 m downwards, the ichnocoenoses development is significantly slowed and only immature dysphotic and aphotic borer communities (dominated by fungi) are encountered. Strong fluctuations of salinity (down to 8%) and temperature (0–20°C) in the euphotic zone indicate most phototrophs present to be considerably euryhaline and eurytherm, while most endolithic fungi appear preferentially in the deeper, more stable marine waters. [ABSTRACT FROM AUTHOR]