| 1. |
- Olempska, Ewa, et al.
(författare)
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Phosphatic bromalites and microfossils from the Furongian (Cambrian) of northern Poland (Baltica) and palaeobiological implications
- 2023
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Ingår i: Palaeogeography, Palaeoclimatology, Palaeoecology. - : Elsevier BV. - 0031-0182. ; 610
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Forskningsöversikt (refereegranskat)abstract
- The Furongian Słowińska Formation in Poland yielded minute three-dimensionally preserved, phosphatic fossils. Based on shape and structure, two distinct types are identified. The first type comprises sinuously folded, coiled, or spiral string-shaped specimens, interpreted as faecal material, coprolites. The specimens measure between less than one and two mm, the strings being long and against their subcircular to circular cross-section (60–150 μm). Many strings are folded in few to more than 30 regular loops, in this exceptional complexity unknown from any comparable fossil or extant faeces. Fully stretched, such strings may have an estimated length of more than three cm, suggesting continuous production of such faeces and resistance very a longer period after defecation until fossilization. Modelling similar strings indicates that the loops were produced by sidewards swinging of the body end of the producer during forward move. EDS analysis of the strings revealed low silica content, but high amounts of phosphate pointing to a organic-rich muddy bottom, which the producers swallowed and eventually became phosphatized as faeces. The producers of this faeces might have been few millimeter long and benthic, not infaunal worms, yet, none of the putative coprolites can be unquestionably ascribed to a particular animal group. The second type of fossils comprises between 100 and 220 μm long ellipsoidal to spherical forms with a smooth but wrinkled surface. They are interpreted as collapsed and deformed eggs or embryos lacking the egg shell, rather than coprolites made of digested and squeezed remains of possibly phosphatocopid crustaceans, the most abundant component of the Polish and Baltoscandian Orsten-type fossil assemblages. The spheres also have a smooth surface, which in all cases is partly broken off, uncovering an internal mass. This ranges from a small hump of possibly embryonic material in a large void, to a completely round body possibly presenting a late shield-bearing embryo filling the entire space underneath the egg shell. We interpret this second type of fossils as the first evidence of eggs in Orsten-type preservation, most likely belonging to phosphatocopid crustaceans.
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| 2. |
- Soussi, Mohamed, et al.
(författare)
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Middle Triassic (Anisian-Ladinian) Tejra red beds and Late Triassic (Carnian) carbonate sedimentary records of southern Tunisia, Saharan Platform : Biostratigraphy, sedimentology and implication on regional stratigraphic correlations
- 2017
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Ingår i: MARINE AND PETROLEUM GEOLOGY. - : Elsevier BV. - 0264-8172. ; 79, s. 222-256
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Forskningsöversikt (refereegranskat)abstract
- The "red beds" of the Triassic succession outcropping at Tejra-Medenine (southern Tunisia, Saharan Platform) have yielded rich fossil assemblages of both freshwater and brackish-marine invertebrates and vertebrates. The new discovered fauna indicates an Anisian-Lower Ladinian age for the Tejra section. Its lowermost part is considered as equivalent of Ouled Chebbi Formation, while the medium and upper parts are considered as equivalent of the Kirchaou Formation. Both sedimentological characteristics and fossil assemblages indicate the increasing marine influences within the middle part of the section and the migration of brackish and freshwater fauna into the lacustrine/playa environment at the top. The marine fauna-rich interval of the Tejra section correlates well with the well-known Myophoria-rich carbonate stratigraphic marker confirming the Middle Triassic (Ladinian) major transgression well recorded eastward in the Tunisian Jeffara basin and in Libya. The use of this Ladinian stratigraphic event in addition to the Carnian carbonate transgressive events of the Jeffara escarpment outcrops was of great help for regional lithostratigraphic correlations between the Triassic outcropping series and those currently buried in Ghadames and Berkine basins. The age of the sandstones of "Trias Argilo-Greseux Inferieur" (TAGI) which forms the main oil and gas reservoir in the Saharan domain is attributed to the Anisian-Carnian and considered as coeval of Ouled Chebbi and Kirchaou Formations of the Dahar escarpment. An updated synthetic stratigraphic chart is proposed for the Triassic of Saharan Platform domain on the basis of the compilation of the new obtained results and the subsurface data taken from published literature.
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| 3. |
- Sulej, Tomasz, et al.
(författare)
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New perspectives on the Late Triassic vertebrates of East Greenland : preliminary results of a Polish−Danish palaeontological expedition
- 2014
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Ingår i: Polish Polar Research. - : Polish Academy of Sciences Chancellery. - 0138-0338 .- 2081-8262. ; 35:4, s. 541-552
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Tidskriftsartikel (refereegranskat)abstract
- The Fleming Fjord Formation (Jameson Land, East Greenland) documents a diverse assemblage of terrestrial vertebrates of Late Triassic age. Expeditions from the turn of the 21st century have discovered many important fossils that form the basis of our current knowledge of Late Triassic Greenlandic faunas. However, due to the scarcity and incompleteness of the fossils and their insufficient study, our understanding of the taxonomic diversity of the Fleming Fjord Formation is hindered. Here, we report the preliminary findings of a Polish−Danish expedition to the Fleming Fjord Formation that took place in 2014. Three areas were visited – the fairly well known MacKnight Bjerg and Wood Bjerg and the virtually unexplored Liasryggen. MacKnigth Bjerg and Liasryggen yielded fossils which promise to significantly broaden our knowledge of vertebrate evolution in the Late Triassic. Stem−mammal remains were discovered at Liasryggen. Other fossils found at both sites include remains of actinopterygians, sarcopterygians, temnospondyl amphibians and various archosaurs (including early dinosaurs). Numerous vertebrate trace fossils, including coprolites, pseudosuchian footprints, theropod and sauropodomorph dinosaur tracks, were also discovered. Newly discovered skeletal remains as well as abundant trace fossils indicate higher tetrapod diversity in the Late Triassic of Greenland than previously thought. Trace fossils also allow inferences of early theropod and sauropodomorph dinosaur behaviour.
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| 4. |
- Sulej, Tomasz, et al.
(författare)
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The earliest-known mammaliaform fossil from Greenland sheds light on origin of mammals
- 2020
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Ingår i: Proceedings of the National Academy of Sciences of the United States of America. - : Proceedings of the National Academy of Sciences. - 0027-8424 .- 1091-6490. ; 117:43, s. 26861-26867
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Tidskriftsartikel (refereegranskat)abstract
- Synapsids are unique in having developed multirooted teeth and complex occlusions. These innovations evolved in at least two lineages of mammaliamorphs (Tritylodontidae and Mammaliaformes). Triassic fossils demonstrate that close to the origins of mammals, mammaliaform precursors were "experimenting" with tooth structure and function, resulting in novel patterns of occlusion. One of the most surprising examples of such adaptations is present in the haramiyidan Glade, which differed from contemporary mammaliaforms in having two rows of cusps on molariform crowns adapted to omnivorous/herbivorous feeding. However, the origin of the multicusped tooth pattern present in haramiyidans has remained enigmatic. Here we describe the earliest-known mandibular fossil of a mammaliaform with double molariform roots and a crown with two rows of cusps from the Late Triassic of Greenland. The crown morphology is intermediate between that of morganucodontans and haramiyidans and suggests the derivation of the multicusped molariforms of haramiyidans from the triconodont molar pattern seen in morganucodontids. Although it is remarkably well documented in the fossil record, the significance of tooth root division in mammaliaforms remains enigmatic. The results of our biomechanical analyses (finite element analysis [FEA]) indicate that teeth with two roots can better withstand stronger mechanical stresses like those resulting from tooth occlusion, than teeth with a single root.
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