8,207 research outputs found

    Latest Cretaceous Vertebrates from the Hateg Basin, Romania

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    The Late Cretaceous was a crucial time for the evolution of life on land, and despite its importance, this period is incompletely understood in many places around the world. The uppermost Cretaceous continental deposits of the HaŇ£eg Basin in western Romania have yielded one of the richest and most diverse vertebrate assemblages of Europe, thus being of paramount importance for understanding European Late Cretaceous ecosystems. Although the HaŇ£eg Basin looks back on a research history of more than 120 years, many open questions about the latest Cretaceous vertebrate assemblages remain. This includes, in particular, their diversity, their phylogenetic and biogeographical relationships, as well as palaeoecological aspects. In order to assess these questions, four key specimens were examined for this thesis, a partial turtle skeleton, two ornithopod braincases and one partial skull of a rhabdodontid dinosaur. The first specimen can be confidently referred to the Dortokidae, a European endemic clade of basal Pleurodires. It is morphologically similar to the genus Dortoka but differs significantly from all previously described species of that genus and thus is assigned to a new species, Dortoka vremiri. Phylogenetic analyses recovered the new taxon in a sister-group relationship with a Paleocene dortokid from western Romania, indicating local survival of the lineage across the K/Pg extinction, as opposed to subsequent immigration, as well as the presence of two distinct dortokid lineages, an eastern and a western European one. Additionally, it was possible to demonstrate that the new species occupied a different ecological niche than the only other sympatric turtle taxon from the HaŇ£eg Basin described before, Kallokibotion bajazidi. The two ornithopod braincase specimens have previously been referred to the rhabdodontid Zalmoxes, although they differ markedly from other braincase specimens of that genus described before. A detailed comparison with basal and more derived ornithopods demonstrated that the peculiar morphology of these two specimens is exclusively found in hadro-sauroids. Therefore, the two specimens are re-assigned to the basal hadrosauroid Telmatosaurus. The final specimen examined is a partial skull that resembles rhabdo-dontid dinosaurs. Despite these similarities, the specimen differs considerably from all other rhabdodontid skulls reported thus far and shows a unique and highly auta-pomorphic anatomy, and therefore, it is assigned to a new genus and species, Transylvanosaurus platycephalus. Two sets of phylogenetic analyses placed the new taxon within Rhabdodontidae but were unable to resolve the in-group relationships. Based on the high degree of similarity between Transylvanosaurus and Rhabdodon from southern France, a particularly close relationship between those taxa is suggested, which indicates a more complex biogeographical history than previously recognised. In addition, Transylvanosaurus differs widely from the sympatric rhabdo-dontid Zalmoxes in its skull proportions, indicating a certain degree of niche partitioning between the two genera. The results of this dissertation show that the alpha-level taxonomic diversity of certain groups was higher than previously thought. Moreover, the phylogenetic relationships of the new taxa indicate more complex biogeographical histories than reconstructed before and differential distribution patterns for different vertebrate groups. Finally, it was possible to detect some degree of niche partitioning between the members of the vertebrate groups.Die Oberkreide (100.5‚Äď66 Ma) war eine entscheidende Periode in der Entwicklungs-geschichte des Lebens an Land und trotz dieser Bedeutung, ist dieser Zeitabschnitt in vielen Teilen der Erde nur unvollst√§ndig verstanden. Die kontinentale Oberkreide des HaŇ£eg Beckens hat eine der reichhaltigsten und diversesten Ansammlungen von Wirbeltieren aus dieser Zeit geliefert, und ist daher von zentraler Bedeutung f√ľr unser Verst√§ndnis f√ľr die oberkretazischen √Ėkosysteme Europas. Obwohl das HaŇ£eg Becken auf eine mehr als 120-j√§hrige Forschungsgeschichte zur√ľckblickt, bleiben viele Fragen √ľber die oberkretazischen Wirbeltiere noch immer offen. Dies beinhaltet im Besonderen ihre Diversit√§t, ihre phylogenetischen und biogeographischen Beziehungen, sowie pal√§o√∂kologische Aspekte. Um diese Fragen zu beantworten, wurden vier Wirbeltierfossilien f√ľr diese Doktorarbeit untersucht, ein Teilskelett einer Schildkr√∂te, zwei Hirnsch√§del ornithopoder Dinosaurier und ein Teilsch√§del eines rhabdodontiden Dinosauriers. Das erste Fossil kann eindeutig den Dortokiden zugeordnet werden, einer endemischen Gruppe basaler Pleurodiren. Es √§hnelt morphologisch der Gattung Dortoka, unterscheidet sich aber erheblich von allen anderen bisher bekannten Arten dieser Gattung und wird daher einer neuen Art zugeordnet, Dortoka vremiri. Phylogenetische Analysen ergaben eine Schwester-gruppen-Beziehung der neuen Art mit Dortokiden aus dem Pal√§oz√§n West-Rum√§niens, was auf das lokale √úberleben dieser Gruppe w√§hrend des K/T Aussterbeereignisses hindeutet und nicht auf sp√§tere Immigration, sowie auf die Existenz zweier getrennter Dortokiden-Gruppen in Ost- bzw. Westeuropa. Des Weiteren konnte nachgewiesen werden, dass die neue Art eine andere √∂kologische Nische besetzte als die einzig andere bekannte Schildkr√∂te aus dem HaŇ£eg Becken, Kallokibotion bajazidi. Die zwei Ornithopoden Hirnsch√§del wurden zuvor dem Rhabdo-dontiden Zalmoxes zugeordnet, obwohl sie sich stark von anderen fossilen Hirn-sch√§deln dieser Gattung unterscheiden. Ein detaillierter Vergleich mit basalen und abgeleiteten Ornithopoden zeigte, dass die eigenartige Morphologie dieser beiden St√ľck ansonsten ausschlie√ülich bei Hadrosauroiden vorkommt. Daher werden beide St√ľcke stattdessen dem basalen Hadrosauroiden Telmatosaurus zugeordnet. Das letzte untersuchte Fossil ist ein Teilsch√§del der √Ąhnlichkeiten zu rhabdodontiden Dinosauriern aufweist. Trotz dieser √Ąhnlichkeiten, unterscheidet sich der Sch√§del deutlich von dem aller anderen Rhabdodontiden und zeigt eine einzigartige und stark autapomorphe Anatomie, und wird folglich einer neuen Gattung und Art zugeordnet, Transylvanosaurus platycephalus. Zwei voneinander unabh√§ngige phylogenetische Analysen ergaben, dass das neue Taxon den Rhabdodontiden angeh√∂rt, waren indes aber nicht in der Lage die Verwandtschaftsverh√§ltnisse innerhalb der Gruppe aufzul√∂sen. Aufgrund der starken √Ąhnlichkeit zwischen Transylvanosaurus und Rhabdodon aus S√ľdfrankreich, wird eine besonders nahe Verwandschaft zwischen diesen Taxa angenommen, was wiederum auf eine kompliziertere biogeographische Vergangenheit hinweist als bisher vermutet. Zudem deutet die stark unterschiedliche Sch√§delanatomie zwischen Transylvanosaurus und dem sympatrischen Zalmoxes auf die Besetzung unterschiedlicher √∂kologischer Nischen hin. Die Ergebnisse diser Dissertation zeigen, dass die Diversit√§t bestimmter Gruppen h√∂her war als bisher gedacht. Des Weiteren deuten die phylogentischen Beziehungen der neuen Taxa darauf hin, dass die Biogeographie komplizierter war als zuvor rekonstruiert und dass die verschiedenen Wirbeltiergruppen unterschiedliche Verbreitungsmuster aufweisen. Schlie√ülich war es m√∂glich die Bestzung unterschiedlicher √∂kologischer Nischen bei angeh√∂rigen derselben Gruppe aufzuzeigen

    Listening to tropical forest soils

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    Acoustic monitoring has proven to be an effective tool for monitoring biotic soundscapes in the marine, terrestrial, and aquatic realms. Recently it has been suggested that it could also be an effective method for monitoring soil soundscapes, but has been used in very few studies, primarily in temperate and polar regions. We present the first study of soil soundscapes using passive acoustic monitoring in tropical forests, using a novel analytical pipeline allowing for the use of in-situ recording of soundscapes with minimal soil disturbance. We found significant differences in acoustic index values between burnt and unburnt forests and the first indications of a diel cycle in soil soundscapes. These promising results and methodological advances highlight the potential of passive acoustic monitoring for large-scale and long-term monitoring of soil biodiversity. We use the results to discuss research priorities, including relating soil biophony to community structure and ecosystem function, and the use of appropriate hardware and analytical techniques

    Middle Pleistocene paleoenvironmental reconstruction through phytolith analysis at the Manyara Beds, northern Tanzania

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    This project is aimed at developing a detailed habitat reconstruction for hominins living at the Manyara Beds of Northern Tanzania during the early Middle Pleistocene using phytolith remains. The dissertation comprises three interlinked, but independent studies. The first study examines the phytolith assemblages from modern surface soils and plants to create a referential baseline for studying phytoliths from the Acacia-Commiphora ecosystem surrounding the Manyara Beds, the same plant regions in which our ancestors reside. Phytoliths from 21 species of plants, including 11 unstudied taxa from this ecosystem, were characterized. Twenty-five composite surface soil samples from five sites were also analyzed. Using Stromberg's 2003 classification and interpretive scheme, this study has demonstrated that the dominant phytoliths for Commiphora are polyhedral epidermal cells, and Acacia is a rare producer of blocky-faceted rectangular plate morphotypes. The second study examines phytolith assemblages from archaeological and non-archaeological sites within the six-meter zone of the uppermost part of the lower Manyara Beds. In general, phytolith assemblage from archaeological and non-archaeological sites confirms the persistence of C4 grasslands. However, varied habitats were available for the Acheulean tool-making hominins at archaeological site MK 4, which featured palms, woody dicots, sedge, and grasslands taxa, including high proportions of warm arid and moist loving C3 and C4 PACMADs and dry adapted C4 chloridoids. There is also a small presence of wet-loving panicoids. The palms, sedges, Commelinaceae, and other aquatic monocots indicate that Manyara Beds were well-watered, at least with the occurrence of freshwater springs or rivers near the Lake shores. Therefore, inferences from phytolith assemblages from the Manyara Beds are consistent with the common predictions of many Plio-Pleistocene sites near the lake shores, pointing to hominin's dependence on water and food resources such as plants and game. The third study presents the analysis of 106 stone tool residue samples from the MK4 site to understand the function of the small flake assemblage found there. Ten tools yielded phytoliths, including two flaked and eight core tools. Phytoliths revealed the exploitation of plant resources, including grasses, palms, sedges, woody dicots, and other unknown taxa

    Conservation status of Brazilian snakes inhabiting the Atlantic Forest of Northeastern Brazil

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    Due to the high level of disturbance in natural ecosystems and the progressive loss of habitats resulting from anthropic occupation, biodiversity conservation represents one of the greatest challenges today. Red lists of threatened species are essential tools for identifying species at risk of extinction and guiding conservation efforts. In this study, we assessed the vulnerability to extinction of 55 snake species that occur in the Atlantic Forest of northeastern Brazil in Paraíba state. We developed vulnerability indices based on 12 factors known to influence the survival of snake populations. To analyze the threat profiles and relative risk levels within the snake community, we employed principal component analysis (PCA) and cluster analysis. Additionally, we compared our findings with existing red lists of threatened species. Our results reveal that only 18% of the snake fauna in this region is free of any threat. The aquatic species Helicops angulatus and Oxyrhopus trigeminus were the snakes that presented the lowest risk of extinction, while Caaeteboia gaeli and Crotalus durissus presented the highest risk of extinction. Two groups of species were considered non-threatened and five groups were considered threatened. Our study provides the first overview on the conservation status of snake species in the northern portion of the Atlantic Forest and contributes to a better evaluation of conservation planning for this group in the region

    The Impacts of Clearcutting on Understory Plants and Culturally Significant Species In Coastal Western Hemlock Forests of Vancouver Island

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    The goal of the study is to understand successional changes in an understory plant community after clear-cut timber harvesting. The forest ecosystem is within the Southern Very Wet Hypermaritime biogeoclimatic subzone in the broader Coastal Western Hemlock zone along the west coast of Vancouver Island. The ecosystem is located in Huu-ay-aht First Nations traditional territory, and the subzone falls within various Nuu-chah-nulth First Nations traditional territories. A chronosequence was used to categorize various stages of forest growth in five successional stages: Regeneration, Immature, Thinning, Mature, and Old-growth. Forests censused ranged in age from 1 to 354 years old with old-growth stages described as stands over 250 years. The leaf cover and stem density of understory plant species were recorded within 83 subplots. These metrics were evaluated with regard to environmental variables (slope aspect, elevation, canopy openness, soil pH, A horizon depth, soil profile depth, tree basal area, tree stem density, ground moss cover, and bare ground cover) to determine which, if any, factors influenced understory species composition and structure. Out of 45 species identified, 19 are culturally significant plant species to the Nuu-chah-nulth First Nations. The species restricted to one successional stage were identified, with emphasis on opportunistic species in early stages and rare species in the Old-growth stage. There was a large decrease in many culturally significant species immediately after clearcutting. There was a large decrease in species (stem density, leaf cover, species richness, species diversity) from the Regeneration stage to the Thinning stage (1 to 80 years); however, these values steadily increased thereafter. Plant leaf cover and stem density were influenced by the amount of light reaching the understory. The natural disturbance regime that shade-tolerant plants are adapted to in these old-growth forests is small-scale gap formations, which clearcutting does not mimic. Timber harvesting options are recommended to better mimic the natural disturbance regime in this region, which is optimal for the understory species in this region. Many rare and culturally significant plant species were negatively impacted by clearcutting. Protecting rare plant species in old-growth forests is important for maintaining forest biodiversity and indigenous cultural practices in the future

    The Latest Occurrence of Stephanorhinus hundsheimensis (Rhinocerotidae) in Europe: The Skeletons from the Cova del Rinoceront Site (Castelldefels, Barcelona).

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    New rhino remains recovered from Cova del Rinoceront (Castelldefels, Barcelona) confirm the presence of Stephanorhinus hundsheimensis (Toula, 1902) at the site and the taxon‚Äôs persistence until the late Middle‚Äďearly Upper Pleistocene in Europe, that is, its latest documented occurrence. The three individuals recovered from the site are compared with specimens of other Pleistocene species, including those of S. hemitoechus, S. kirchbergensis and Coelodonta antiquitatis, but their anatomical characteristics (a long skull, moderate occipital elevation, partial nasal septum, and slender zygomatic arch) do not coincide with the latter‚Äôs documented features. Certain similarities are found with the most frequently occurring rhinocerotid at that time in the Iberian Peninsula, S. hemitoechus, but the cranial features of the latter differ. The anatomical characteristics of the Cova del Rinoceront individuals coincide most closely with those of S. hundsheimensis (i.e., a high occipital face, with rounded proximolateral angles and oblique lateral borders, as well as the frontoparietal angle, and facial development). Despite the marked overlaps in the general measurements of S. hundsheimensis and S. hemitoechus, many (cranial and postcranial) dimensions of the Cova del Rinoceront individuals coincide more closely with those of the former, although some bone proportions are more similar to those of the latter specimens. Therefore, S. kirchbergensis and C. antiquitatis can be discarded as they tend to be larger, more robust species

    Charles Darwin's discovery of Devonian fossils in the Falkland Islands, 1833, and its controversial consequences

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    In March 1833 Charles Darwin discovered Devonian fossils in the Falkland Islands. He was excited by his find but could have had little premonition of the long-running geological controversy that he was initiating. Darwin's fossils matched a coeval South African fauna, and as further collections were made the association was apparently strengthened. A particularly important contribution arose around 1910 through collaborations between a local collector, Constance Allardyce, and professional palaeontologists: Ernest Schwarz in South Africa and John Clarke in the USA. The accumulating evidence was seized upon by the early proponents of ‚Äėdisplacement theory‚Äô - continental drift - notably Alexander Du Toit, who relocated the Falkland Islands northward for his 1927 South Atlantic reconstruction. A more radical, but geologically sounder proposal arose in 1952 when Ray Adie suggested that the Falkland Islands, rotated through 180¬į, had originated as the eastward culmination of the Cape Fold Belt and Karoo Basin. In effect, Adie had presciently described a rotated microplate, perhaps the first on record. An opposing view saw the Falkland Islands as part of a fixed, South American promontory, and argument around these two contrasting interpretations of South Atlantic geology continues to the present day

    Forest leaf litter beetles of Taiwan: first DNA barcodes and first insight into the fauna

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    We report the publication of 953 DNA barcodes of forest leaf litter beetles from central Taiwan, in total representing 334 spe- cies of 36 beetle families. This is the first bulk of data from the Taiwanese Leaf Litter beetles project focused on uncovering the under-explored diversity of leaf litter beetles across Taiwan. Based on these data, we provide the first records of the following taxa for Taiwan: family Sphindidae (genus Aspidiphorus Ziegler, 1821); tribes Trichonychini, Ctenistini, and Bythinoplectini (all Staphylinidae: Pselaphinae); genera Gyrelon Hinton, 1942, Thyroderus Sharp, 1885, Cautomus Sharp, 1885 (all Cerylonidae), Dermatohomoeus Hlisnikovsk√Ĺ, 1963 (Leiodidae), Paraploderus Herman, 1970 (Staphylinidae: Oxytelinae), Thinocharis Kraatz, 1859 (Staphylinidae: Paederinae), Cephennodes Reitter, 1884, Napoconnus Franz, 1957 (both Staphylinidae: Scydmaeninae), Bicava Belon, 1884 (Latridiidae), Otibazo Morimoto, 1961, Seleuca Pascoe, 1871 and Acallinus Morimoto, 1962 (all Curculioni- dae); species Oodes (Lachnocrepis) japonicus (Bates, 1873) (Carabidae: Licininae), Drusilla obliqua (Bernhauer, 1916) (Staphylin- idae: Aleocharinae) and Coccotrypes advena Blandford, 1894 (Curculionidae: Scolytinae). The records of Anapleus Horn, 1873 (Histeridae) and Batraxis Reitter, 1882 (Staphylinidae: Pselaphinae) have been confirmed. The male of Sivacrypticus taiwanicus Kaszab, 1964 (Archeocrypticidae) is described for the first time. Gyrelon jenpani Hu, Fik√°ńćek & Matsumoto, sp. nov. (Cerylon- idae) is described, illustrated, and compared with related species. DNA barcodes associated larvae of 42 species with adults, we are concisely illustrating some of these: Oodes japonicus, Perigona cf. nigriceps Dejean, 1831 (both Carabidae), Ptilodactyla sp. (Ptilodactylidae), Maltypus ryukyuanus Wittmer, 1970 (Cantharidae), Drusilla obliqua, Myrmecocephalus brevisulcus (Pace, 2008), Diochus sp., Mimopinophilus sp. (all Staphylinidae), Stelidota multiguttata Reitter, 1877, Lasiodites inaequalis (Grouvelle, 1914) (both Nitidulidae), Lagria scutellaris Pic, 1910, and Anaedus spinicornis Kaszab, 1973 (both Tenebrionidae). We also report the first cases of Rickettsia infections in Scydmaeninae and Pselaphinae. All data (sequences, metadata, and voucher photos) are made public in BOLD database and in a Zenodo Archive

    The Mongolian Remodeling and the structure of Anoplocephalid cestode diversity

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    Ecological disruption plays an important role in structuring diversity of flora, fauna, and their parasites. At the end of the Eocene, climatic change across Asia resulted in a faunal turnover (the Mongolian Remodeling) as rodents diversified and larger mammals declined. Throughout the Oligocene, the landscape in Asia was characterized by episodic climatic and landscape changes resulting in pulses of rodent diversification. The role of historical ecological disruption in Central Asia in structuring the diversity of parasites of small rodents has not been thoroughly investigated. The hyper-diverse Paranoplocephala species complex (family: Anoplocephalidae) infect rodents throughout the Holarctic and present an opportunity to investigate the consequences of ecological disruption on the diversity of parasites. Here, I use whole mitogenome sequencing to produce a well-resolved phylogeny showing relationships within the Paranoplocephala species complex. I test the hypotheses that the Mongolian Remodeling initiated diversification and subsequent recurrent episodes of climatic change increased the tempo of diversification within this parasite assemblage. Using mitochondrial genome sequencing, I built the most robust phylogenetic tree of seven known species and eight previously unknown lineages. A clock calibration estimate put the temporal origin of the Paranoplocephala species complex approximately 42 MYA and lineage through time tests showed more diversification occurred in deeper time. Results indicated multiple trans-Beringian dispersal events and numerous host-colonization events, consistent with ecological disruption playing an important role in structuring parasite diversity
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