| 1. |
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| 2. |
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| 3. |
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| 4. |
- Blom, Henning, Dr, 1969-, et al.
(författare)
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Thelodont scales from the Lower Devonian of Novaya Zemlya Archipelago, Arctic Russia.
- 2022
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Ingår i: Spanish Journal of Palaeontology. - : Universitat de Valencia. - 2255-0550 .- 2660-9568.
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Tidskriftsartikel (refereegranskat)abstract
- Scales of a new thelodont species, Amaltheolepis terranovi sp. nov., are described from the upper Emsian, Lower Devonian Shevchenkinskaya Formation of Novaya Zemlya, Arctic Russia. The new species shows strong resemblance with the Emsian “Verdalen assemblage” from Spitsbergen, supporting an Emsian age for the upper part of the Shevchenkinskaya Formation. This conclusion in the context of the various Amaltheolepisassemblages from Spitsbergen allows for a more accurate comparison and correlation between assemblages from different regions in the Northern Hemisphere, suggesting that the type species, Amaltheolepis winsnesifrom Spitsbergen, is Eifelian in age
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| 5. |
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| 6. |
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| 7. |
- Fadel, Alexandre, et al.
(författare)
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Palaeoenvironmental signatures revealed from rare earth element (REE) compositions of vertebrate microremains of the Vesiku Bone Bed (Homerian, Wenlock), Saaremaa Island, Estonia
- 2015
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Ingår i: Estonian journal of earth sciences. - : Estonian Academy Publishers. - 1736-4728 .- 1736-7557. ; 64:1, s. 36-41
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Tidskriftsartikel (refereegranskat)abstract
- Rare earth elements (REEs) have been analysed from fossil vertebrate microremains (thelodont scales) from the Vesiku Bone Bed, Saaremaa, Estonia, using in situ microsampling by laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS). Well-preserved scales of three species of the genus Thelodus (T. carinatus, T. laevis and Thelodus sp.) show very uniform REE patterns with slightly lower overall REE concentrations in enameloid than in dentine, with enrichment in middle REEs, depletion in heavy REEs and pronounced negative europium anomaly, but no cerium anomaly. The results of this study suggest a similar diagenetic history and possibly contemporaneous habitats for all three Thelodus species, as well as possible suboxic to anoxic conditions of the bottom and pore waters during the formation of the Vesiku Bone Bed.
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| 8. |
- Histon, Kathleen, et al.
(författare)
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Preface
- 2015
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Ingår i: Estonian journal of earth sciences. - 1736-4728 .- 1736-7557. ; 64:1, s. 1-2
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Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)abstract
- Evolutionary palaeoecology and palaeobiogeography: year 4 of the IGCP-591 project 'The Early to Middle Palaeozoic Revolution - Bridging the Gap between the Great Ordovician Biodiversification Event and the Devonian Terrestrial Revolution
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| 9. |
- Mergl, Michal, et al.
(författare)
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Vertebrate Microremains From The Pragian, Emsian And Eifelian Of The Prague Basin (Czech Republic)
- 2017
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Ingår i: Folia Musei rerum naturalium Bohemiae occidentalis. Geologica et Paleobiologica. - : Walter de Gruyter GmbH. - 1805-286X. ; 51:1/2, s. 1-12
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Tidskriftsartikel (refereegranskat)abstract
- The vertebrate faunas in limestone samples of the Early and Middle Devonian ages (Pragian, early Emsian, late Emsian, and latest Eifelian) which were collected from five localities in the Barrandian area, Bohemia, include scales, tesserae, bones, and teeth of acanthodians, placoderms, chondrichthyans, and sarcopterygians. Although the vertebrate remains are not abundant the assemblages are significant in being dominated by particular taxa. Apart from undetermined microremains the genera Cheiracanthoides, Laliacanthus, Nostolepis, and Tassiliodus were determined.
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| 10. |
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| 11. |
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| 12. |
- Qvarnström, Martin, et al.
(författare)
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Synchrotron phase-contrast microtomography of coprolites generates novel palaeobiological data
- 2017
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Ingår i: Scientific Reports. - : Nature Publishing Group. - 2045-2322. ; 7
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Tidskriftsartikel (refereegranskat)abstract
- Coprolites (fossil faeces) reveal clues to ancient trophic relations, and contain inclusions representing organisms that are rarely preserved elsewhere. However, much information is lost by classical techniques of investigation, which cannot find and image the inclusions in an adequate manner. We demonstrate that propagation phase-contrast synchrotron microtomography (PPC-SR mu CT) permits high-quality virtual 3D-reconstruction of coprolite inclusions, exemplified by two coprolites from the Upper Triassic locality Krasiejow, Poland; one of the coprolites contains delicate beetle remains, and the other one a partly articulated fish and fragments of bivalves.
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| 13. |
- Qvarnström, Martin, et al.
(författare)
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Vertebrate coprolites (fossil faeces) : An underexplored Konservat-Lagerstatte
- 2016
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Ingår i: Earth-Science Reviews. - : Elsevier BV. - 0012-8252 .- 1872-6828. ; 162, s. 44-57
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Forskningsöversikt (refereegranskat)abstract
- Fossilized soft tissues of animals (e.g. muscles, hair and feathers) are valuable sources of palaeobiological information, but a poor preservation potential makes them undesirably scarce in the fossil record. The aim of this review is to summarize main findings, current progress and the analytical constraints of detecting fossilized soft tissues in coprolites from, mainly, freshwater and terrestrial carnivorous vertebrates. We conclude that soft-tissue inclusions in coprolites are sources of two important lines of information: the fossils can be put in a direct palaeoecological context, and characters of extinct taxa are more likely preserved in the phosphate-rich taphonomic microenvironment of coprolites than elsewhere. As a result, it is possible to unravel the deep-time origins of host-parasite relations, to understand ancient trophic food webs and detect new soft-tissue characters of different animal groups. Examples of the latter include muscle tissues from a tyrannosaurid prey, tapeworm eggs (including a developing embryo) in a Permian shark coprolite, as well as hair from multituberculates and, probably, from stem-mammals (Therapsids). Additionally, the use of coprolites in an archaeological context is briefly reviewed with focus on key aspects that may become implemented in studies of pre-Quaternary specimens as well. In summary, there is a wide range of information that can be extracted from coprolites, which has not yet been fully explored in palaeontological studies.
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| 14. |
- Qvarnström, Martin, 1989-
(författare)
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Who ate whom? Paleoecology revealed through synchrotron microtomography of coprolites (fossil feces)
- 2020
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Fossil droppings, known as coprolites, are being increasingly recognized as a valuable source of paleoecological information with special regard to diets, parasitism, and physiology of extinct taxa. Here, it is suggested that the excellent preservation and amount of inclusions in the coprolites (e.g. food residues and parasites) qualifies them as Lagerstätten – deposits with exceptional paleontological information. However, two interlinked problems commonly arise when they are studied. Firstly, it is often difficult to tie coprolites to producers and, secondly, it is challenging to recognize the fragmented and randomly distributed inclusions in their matrix. Here I use propagation phase-contrast synchrotron microtomography (PPC-SRμCT) in combination with other techniques to solve these problems. As a result, the oldest known example of archosaurian osteophagy is uncovered based on inter alia the occurrence of serrated teeth and many crushed bones in coprolites assigned to the Late Triassic theropod-like archosaur Smok wawelski. Osteophagy has previously been thought to be rare among extinct archosaurs with the exception of Late Cretaceous tyrannosaurids. This suggests some degree of ecological convergence between the tyrannosaurids and S. wawelski. Furthermore, exceptionally-preserved beetle remains are discovered in coprolites tentatively assigned to the Triassic dinosauriform Silesaurus opolensis, which had a specialized dentition and possessed beak-shaped jaws that were likely used to peck insects off the ground. Moreover, pterosaur coprolites are shown to contain similar food residues as found in droppings of recent flamingos, implying that some Late Jurassic pterosaurs were filter feeders. I argue that such paleoecological studies have a large impact on our understanding of ancient animals, and that studies of coprolites can unravel parts of ancient food webs in unprecedented ways. Information on past food webs may, in turn, be used to analyze trophic changes through time, which could cast new light on big evolutionary events. This is demonstrated by reconstructing trophic structures in early Mesozoic assemblages that represent snapshots of three stages of early dinosaur evolution.
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| 15. |
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| 16. |
- Verniers, Jacques, et al.
(författare)
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SILURIAN
- 2008
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Ingår i: The Geology of Central Europe. - : Geological Society of London. - 9781862392458 ; , s. 249-302
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Bokkapitel (refereegranskat)
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| 17. |
- Verniers, Jacques, et al.
(författare)
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Silurian : The Geology of Central Europe
- 2008
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Ingår i: Geological Society Special Publication. - 0305-8719 .- 2041-4927. ; 1, s. 249-302
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Tidskriftsartikel (refereegranskat)
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| 18. |
- Weber, Katrin, et al.
(författare)
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Dental microwear texture analysis on extant and extinct sharks : Ante- or post-mortem tooth wear?
- 2021
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Ingår i: Palaeogeography, Palaeoclimatology, Palaeoecology. - : Elsevier. - 0031-0182 .- 1872-616X. ; 562
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Tidskriftsartikel (refereegranskat)abstract
- Sharks are apex-predators that play an important role in past and present aquatic food webs. However, their diet - especially in extinct species - is often not well constrained. Dental microwear texture analysis (DMTA) has been successfully applied to reconstruct diet and feeding behaviours of different aquatic and terrestrial vertebrates. However, unlike in mammals, food-to-tooth contact in sharks is rather limited because only larger prey is manipulated before swallowing. Together with a fast tooth replacement rate, this reduces wear on individual teeth. Here, we present an explorative study of dental microwear texture on extant and extinct sharks to test whether ante-mortem wear is related to ingested diet or habitat preferences and resistant to post-mortem alteration processes. Shark teeth from 24 modern species and 12 fossil species from different localities were measured. As an additional comparison, extant shark teeth of Carcharhinus plumbeus were tumbled in sediment-water suspensions to simulate post-mortem mechanical alteration by sediment transport. Only three of the twelve extant shark species with three or more specimens had significantly different dental surface textures. Furthermore, no clear relation between food or habitat preferences and ante-mortem dental wear features was detected for this sample set. Tumbling modern shark teeth with siliciclastic sediment of four different grain size fractions led to increasing complexity of the dental surface. Fossil specimens resemble these experimentally altered shark teeth more in complexity and roughness. Thus, fossil shark teeth seem to display either very different (e.g. harder) diet-related wear or a strong degree of post-mortem alteration. Based on our restricted sample size, dental wear of shark teeth does overall not seem to simply reflect dietary differences; hence, it is difficult to use DMTA as reliable dietary reconstruction, in either extant nor extinct sharks.
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| 19. |
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| 20. |
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| 21. |
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| 22. |
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| 23. |
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| 24. |
- Zigaite, Zivile, et al.
(författare)
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Do fossil vertebrate biominerals hold the key to Palaeozoic climate?
- 2012
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Konferensbidrag (refereegranskat)abstract
- Fossil vertebrate hard tissues - teeth and dermoskeleton - are considered among the most geochemically stable biominerals, and therefore are widely used for palaeoenvironmental and palaeoclimatic reconstructions. Elemental and isotopic compositions of fossil dental tissues may provide unique palaeoenvironmental information, ranging from the diet and trophic positions on a food chain, to the palaeosalinity and water temperatures of ancient seas. However, before starting any geochemical interpretations, the preservation potential of fossil tissues must be studied carefully, considering possible alteration of the primary geochemical composition. Evaluation of fossil hard tissue preservation can be made by semiquantitative spot geochemistry analyses on fine polished teeth and scale thin sections using Energy Dispersive X-ray Spectroscopy (EDS), and help to roughly preview the chemical composition. The Electron Backscatter Diffractometry (EBSD) is useful to examine the cristallinity and possible structural alterations. In addition, rare earth element (REE) abundances can be measured in situ within the fine fossil tissues (such as enamel vs. dentine) using Laser Ablation Inductively Coupled Plasma Mass-spectrometry (LA-ICP-MS), and give us information about the selective geochemical resilience between separate vertebrate hard tissues. To conclude, in order to decipher the geochemical signal of fossil biominerals correctly, the evaluation of preservation should be the starting point to any further geochemical studies.
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| 25. |
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| 26. |
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| 27. |
- Zigaite, Zivile
(författare)
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Endemic thelodonts (Vertebrata: Thelodonti) from the Lower Silurian of central Asia and southern Siberia
- 2013
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Ingår i: Earth and environmental science transactions of the Royal Society of Edinburgh. - 1755-6910 .- 1755-6929. ; 104:2, s. 123-143
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Tidskriftsartikel (refereegranskat)abstract
- New fossil vertebrate microremains from the Lower Silurian of NW Mongolia, Tuva and S Siberia have been discovered, and previous collections of thelodonts (Vertebrata: Thelodonti) from this region re-studied, figured and described, following recent advances in morphology and systematics of thelodont scales. As a result, six thelodont species are described here and attributed to two families and three genera. An emended diagnosis is given for each species. Morpohological scale varieties of each species are revised, and the squamation types are introduced to the species descriptions, resulting in newly grouped morphological sets of scales. The previously monotypic genus Talimaalepis Zigaite, 2004, is proposed to contain two different species; therefore, two new combinations of morphological scale sets of two species are described for the first time. Both of them show transitional scale structure between the genera Loganellia (family Loganellidae) and Helenolepis (family Phlebolepididae). Two of the thelodont genera, Angaralepis and Talimaalepis, as well as all the six species, are endemic and not known anywhere else in the world. They are accompanied by a variety of other peculiar early vertebrates, such as mongolepids, two endemic genera of acanthodians, and putative galeaspids. This work enhances our knowledge of early Silurian vertebrate diversity, and provides evidence of regional palaeoenvironmental conditions and palaeogeographical relationships of the Siberia and Tuva terranes.
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| 28. |
- Zigaite, Zivile, et al.
(författare)
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Geochemistry of dental bioapatite, the key to palaeoclimate
- 2013
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Ingår i: Proceedings of the 3rd IGCP 591 Annual Meeting, Lund, Sweden, 9-19 June 2013. - Lund : Department of Geology, Lund University. - 9789186746872 ; , s. 361-362
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Konferensbidrag (refereegranskat)
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| 29. |
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| 30. |
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| 31. |
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| 32. |
- Zigaite, Zivile, et al.
(författare)
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New observations on the squamation patterns of articulated specimens of Loganellia scotica (Traquair, 1898) (Vertebrata : Thelodonti) from the Lower Silurian of Scotland
- 2012
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Ingår i: Geodiversitas. - : Museum National d'Histoire Naturelle, Paris, France. - 1280-9659 .- 1638-9395. ; 34:2, s. 253-270
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Tidskriftsartikel (refereegranskat)abstract
- Articulated squamations of Loganellia scotica (Traquair, 1898) from the Lower Silurian Lesmahagow inliers of southern Scotland have been studied. They include seven articulated specimens, three of them representing complete thelodont fossils, and four partially preserved postpectoral, precaudal and caudal parrs of the exoskeleton. All the five main types of thelodont scales that is rostral, cephalo-pectoral, postpectoral, precaudal and pinnal sacles, as well as respective squamation patterns have been observed on articulated specimens. The specific orbital, branchial, and bucco-pharyngeal scales, characteristic of L. scotica, have not been found due to the poor or non-preservation of these particular areas within the specimens studied. Tail morphology and squamation pattern of the caudal fin have been studied with particular attention, and the constitution of the caudal fin rays has been analyzed. The rostral squamation pattern is argued to be characteristic to L. scotico.
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| 33. |
- Žigaitė, Živilė, et al.
(författare)
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New vertebrate assemblages from the Andrée Land Group, Spitsbergen, and their biostratigraphic significance
- 2010
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Ingår i: Programme and Abstracts. ; , s. 80-81
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- The Lower and Middle Devonian successions of Spitsbergen provide excellent examples of vertebrate biostratigraphy applied to sedimentary basin analysis. A number of previous works on the Red Bay Group (Lochkovian, Lower Devonian) made a notable study of the earliest Devonian vertebrate record, and their use in biostratigraphy. Our current study concerns the Lower to Middle Devonian of the Andrée Land Group, which comprises the Wood Bay Formation, spanning from Pragian to Emsian in age, and the Grey Hoek Formation, representing the Eifelian. It consists of thick layers of terrigenous sediments, the stratigraphy is largely based on the lithofacies.Two new thelodont assemblages are considered to represent different depostional phases of the late Lower - early Middle Devonian of the Andrée Land Group. The first, older assemblage comprises turiinid, talivaliid, and furcacaudid thelodonts, and identifies the lower Wood Bay Formation. The second, younger assemblage is prevailed by the talivaliid thelodont Amaltheolepis winsnesi, and is characteristic for the upper Wood Bay Fm., as well as the lower Grey Hoek Fm. The recognition of these two new thelodont assemblages allows us to precise the relative age of the Lower – Middle Devonian strata.
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| 34. |
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| 35. |
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| 36. |
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| 37. |
- Zigaite, Zivile, et al.
(författare)
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Palaeobiogeography of Early Palaeozoic vertebrates
- 2013
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Ingår i: Early Palaeozoic Biogeography and Palaeogeography. - London. - 9781862393738 ; 38:1, s. 449-460
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Konferensbidrag (refereegranskat)abstract
- The oldest known Palaeozoic vertebrate record currently is Early Cambrian in age. The first taxa with mineralized exoskeletons are at least Ordovician in age, followed by a sporadic fossil record with Talimaa’s Gap of c. 3 myr in the Rhuddanian (earliest Silurian). Ordovician and Silurian vertebrate faunas are dominated by ‘agnathans’. Early Palaeozoic vertebrates occupied a wide range of environments: nearshore marine to restricted marine in the Ordovician, and on the marine epicontinental shelves of the Silurian. Silurian vertebrates are useful biostratigraphical indicators, as well as good markers of palaeocontinental margins. Two main palaeobiogeographical units are renamed for the Ordovician: a Gondwana Realm and a Laurentia–Siberia–Baltica Realm. Vertebrate fossil localities are more numerous in the Silurian; therefore a series of palaeobiogeographical provinces and realms are defined on Laurentia, Baltica, Avalonia, Siberia, South China and East Gondwana. More discoveries of Silurian vertebrate-bearing localities should certainly help to define additional provinces, in particular along the northern margins of Gondwana and in SE Asia.
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| 38. |
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| 39. |
- Zigaite, Zivile, et al.
(författare)
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Palaeoenvironments revealed by rare-earth element systematics in vertebrate bioapatite from the Lower Devonian of Svalbard
- 2016
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Ingår i: Canadian journal of earth sciences (Print). - : Canadian Science Publishing. - 0008-4077 .- 1480-3313. ; 53:8, s. 788-794
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Tidskriftsartikel (refereegranskat)abstract
- In situ rare-earth element (REE) compositions have been measured in early vertebrate microremains from the Lower Devonian basin of Andree Land (Svalbard), with the aim of obtaining information about their early depositional environment and potential reworking. Vertebrate microremains with different histology were used for the analyses, sourced from two different localities of marginal marine to freshwater sediments from geographically distant parts of the Grey Hoek Formation (Skamdalen and Tavlefjellet members). We selected thelodont and undescribed ? chondrichthyan scales, which allowed us to define potential taxonomic, histological, and taphonomic variables of the REE uptake. Results showed REE concentrations to be relatively uniform within the scales of each taxon, but apparent discrepancies were visible between the studied localities and separate taxa. The compilation of REE abundance patterns as well as REE ratios have revealed that thelodont and ? chondrichthyan originating from the same locality must have had different burial and early diagenetic histories. The shapes of the REE profiles, together with the presence and absence of the Eu and Ce anomalies, equally suggested different depositional and diagenetic environments for these two sympatric taxa resulting from either stratigraphical or long-distance reworking. The REE concentrations appear to have visible differences between separate dental tissues, particularly between enameloid and dentine of thelodonts, emphasizing the importance of in situ measurements in microfossil biomineral geochemistry.
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| 40. |
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| 41. |
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| 42. |
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| 43. |
- Zigaite, Zivile, et al.
(författare)
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Rare earth elements (REEs) in vertebrate microremains from the upper Pridoli Ohesaare beds of Saaremaa Island, Estonia : geochemical clues to palaeoenvironment
- 2015
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Ingår i: Estonian journal of earth sciences. - : Estonian Academy Publishers. - 1736-4728 .- 1736-7557. ; 64:1, s. 115-120
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Tidskriftsartikel (refereegranskat)abstract
- Rare earth element (REE) compositions of Nostolepis sp. scales, spines, plates and tesserae from Ohesaare bone beds were measured by in situ microsampling using laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS). The obtained REE concentrations, normalized to Post-Archean Australian Shale concentrations, were evaluated using basic geochemical calculations and quantifications. The REE compositions were nearly identical across all the morphotypes and histologies of Nostolepis microremains, showing flat REE patterns with slight depletion in heavy REEs. There was no visible enrichment in middle REEs, indicating good geochemical preservation of bioapatite and absence of any pronounced fractionated REE incorporation during later stages of diagenesis. The shale-normalized (La/Yb)(SN) and (La/Sm)(SN) REE ratio compilations indicated adsorption as the dominating REE uptake mechanism across all datapoints. The absence of well-defmed Ce anomaly suggested oxic palaeoseawater conditions, which agrees with the existing interpretations of the Ohesaare sequence as high-energy shoal and regressive open ocean sedimentary environments.
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| 44. |
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| 45. |
- Žigaitė, Živilė, et al.
(författare)
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REE compositions in fossil vertebrate dental tissues – key to biomineral preservation
- 2011
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Ingår i: The Palaeontological Association Newsletter.
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- Rare earth element (REE) abundances have been measured in a number of Palaeozoic and Mesozoic vertebrate hard tissues (teeth and dermoskeleton) using laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS). Fossil vertebrate analysed comprise scales and tesserae of Silurian and Devonian thelodonts, chondrichthyans, galeaspids, mongolepids, spines of acanthodians, as well as teeth of Cretaceous lungfish and marine reptiles.Pre-evaluation of fossil preservation level has been made by semi-quantitative spot geochemistry analyses on fine polished teeth and scale thin sections, using energy dispersive X-ray spectroscopy (EDS). Silicification of bioapatite, together with elevated heavy element concentrations corresponded to fossil tissue structure and colour alteration. Stable oxygen isotope measurements (δ18O) of bulk biomineral have been conducted in parallel, generally yielding lower heavy oxygen values in stronger alterated teeth and scales. Clear distinction in REE concentrations was observed between dentine and enamel of Cretaceous plesiosaurs, suggesting enamel to be more geochemically resistant to diagenetic overprint.
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| 46. |
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| 47. |
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| 48. |
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| 49. |
- Zigaite, Zivile, et al.
(författare)
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Stable oxygen isotopes of dental biomineral : differentiation at the intra- and inter-tissue level of modern shark teeth
- 2014
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Ingår i: GFF. - : Informa UK Limited. - 1103-5897 .- 2000-0863. ; 136:1, s. 337-340
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Tidskriftsartikel (refereegranskat)abstract
- In situ oxygen isotopic composition of the sandbar shark (Carcharhinus plumbeus) teeth grown at a constant water temperature and salinity were analysed by high precision and high spatialresolution secondary ion mass spectrometry, targeting dental biomineral within the parallel-bundled enameloid (PBE), the tangle-bundled enameloid (TBE) and the dentine. Measured O-18 values had comparable inter-tissue variability in each tooth analysed. The PBE enameloid had the smallest scatter of oxygen isotope ratios, while the TBE enameloid had slightly higher intra-tissue variation of O-18, but similar average values. The dentine had largest variability and lower average O-18. The enameloid of shark teeth is therefore recommended as a target biomineral and a preferential biogeochemical reference for environmental and palaeoenvironmental studies.
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| 50. |
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