6 resultados para Palaeobiology


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Recent years have seen increased interest in skeletal populations from the Imperial Roman Age in Italy, but much less is known about diet and standards of living in the subsequent medieval period. To fill this gap, we conducted a morphological analysis of human remains from Albano, an Italian town near Rome, as well as a stable isotope analysis of bone collagen to reconstruct diet. The sample was recovered from a Medieval cemetery (1040–1220 cal. yr. BP) located in the gardens of the historical Palazzo Doria Pamphili in Albano. A minimum number of 40 individuals (31 adults and 9 sub-adults) were examined using standard methods. Though the general health status of the population was good, signs of cribra orbitalia and diffuse enthesopathies were noted during the morphological examination. Stable carbon and nitrogen isotope analyses of the bone collagen from 24 adult humans and three faunal bones indicate that the diet of the population may be described as predominantly terrestrial and C3-plant based although the data for some of the individuals suggest a modest consumption of C4-(millet) based or aquatic proteins. No evidence of significant dietary differences between the sexes was found. The comparison of the isotope data from Albano with those from populations recovered in the same region is consistent with a shift from a terrestrial, possibly plant foods-dominated subsistence in the Early Middle Ages to a diet with a higher contribution from animal proteins, both terrestrial and aquatic, in the Later Middle Ages.

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The three-dimensional reconstructions of Phoebichnus trochoides and Schaubcylindrichnus (Palaeophycus) heberti created as part of this thesis allow us to fully understand and characterize the three-dimensional morphology and palaeobiology of these common taxa. Three-dimensional reconstructions demonstrate that P. trochoides is a large stellate burrow composed of numerous long galleries produced by a deposit feeding organism. This study reports for the first time that the central zone is composed of stacked disk-shaped layers of highly bioturbated sediment, the radial burrows are composed of a sand-rich lining of pelleted annuli surrounding an active sand-rich fill, and the presence of subtle conical features above the radial galleries that are inferred to result from collapse cone feeding. Reconstructions of heberti demonstrate that the thick walled burrows are composed of sand-rich annular rings, are a broad U-shape, and may be either clustered or isolated. Our observations show that the morphology of heberti is inconsistent with the generic diagnosis of Palaeophycus, but is morphologically comparable to Schaubcylindrichnus, and is herein synonymised with Schaubcylindrichnus to create S. heberti comb. nov. The three-dimensional reconstructions have revealed a number of hitherto unknown morphological elements to both taxa which has facilitated new interpretations of the trace-makers behaviour. The data improves the taxonomic understanding of both P. trochoides and S. heberti which require significant taxonomic change and emendation of diagnoses at the species and genus level.

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Réalisé en cotutelle avec le Département de Préhistoire du Muséum national d’Histoire naturelle (Paris, France), École doctorale « Sciences de la nature et de l’Homme » (ED 227)

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A new species of Gyracanthides from the mid-Visean Ducabrook Formation of Middle Paddock site, near Springsure in the Drummond Basin, central Queensland, is based on isolated three-dimensionally preserved elements. The specimens comprise paired and unpaired spines and pectoral girdle elements, procoracoids and scapulocoracoids, and include growth series. The morphology, especially of the shoulder girdle bones and the form and tubercular ornamentation of the paired fin spines, is used to distinguish the new taxon. These characters also help differentiate the numerous described gyracanthid species. Aspects of palaeobiology including possible sexual dimorphism are explored. A hypothetical reconstruction of the fish is based on our interpretation of the articulation of isolated elements combined with examination of wear patterns on fin spines. Gyracanthides hawkinsi sp. nov. is compared with other Australian taxa as well as with gyracanthids from North America, Europe, Russia, Iran, Africa and Antarctica, some of which are tentatively reassigned here to the Gondwanan genus Gyracanthides.

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Fossil associations from the middle and upper Eocene (Bartonian and Priabonian) sedimentary succession of the Pamplona Basin are described. This succession was accumulated in the western part of the South Pyrenean peripheral foreland basin and extends from deep-marine turbiditic (Ezkaba Sandstone Formation) to deltaic (Pamplona Marl, Ardanatz Sandstone and Ilundain Marl formations) and marginal marine deposits (Gendulain Formation). The micropalaeontological content is high. It is dominated by foraminifera, and common ostracods and other microfossils are also present. The fossil ichnoasssemblages include at least 23 ichnogenera and 28 ichnospecies indicative of Nereites, Cruziana, Glossifungites and ?Scoyenia-Mermia ichnofacies. Body macrofossils of 78 taxa corresponding to macroforaminifera, sponges, corals, bryozoans, brachiopods, annelids, molluscs, arthropods, echinoderms and vertebrates have been identified. Both the number of ichnotaxa and of species (e. g. bryozoans, molluscs and condrichthyans) may be considerably higher. Body fossil assemblages are comparable to those from the Eocene of the Nord Pyrenean area (Basque Coast), and also to those from the Eocene of the west-central and eastern part of South Pyrenean area (Aragon and Catalonia). At the European scale, the molluscs assemblages seem endemic from the Pyrenean area, although several Tethyan (Italy and Alps) and Northern elements (Paris basin and Normandy) have been recorded. Palaeontological data of studied sedimentary units fit well with the shallowing process that throughout the middle and late Eocene occurs in the area, according to the sedimentological and stratigraphical data.

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The Early Miocene Napak XV locality (ca 20.5 Ma), Uganda, has yielded an interesting assemblage of fossils, including the very well represented amphicyonid Hecubides euryodon. The remarkable find of a nearly complete mandible, unfortunately with poorly preserved dentition, together with new dental remains allow us to obtain a better idea about the morphology and variability of this species. Additionally, we describe a newly discovered mandible of Hecubides euryodon from the Grillental-VI locality (Sperrgebiet, Namibia), which is the most complete and diagnostic Amphicyonidae material found in this area. Comparisons with Cynelos lemanensis from Saint Gérand le Pouy (France), the type locality, and with an updated sample of the species of amphicyonids described in Africa leads us to validate the genus Hecubides. Hecubides would be phylogenetically related to the medium and large size species of Amphicyonidae from Africa, most of them now grouped into the genera Afrocyon and Myacyon, both endemic to this continent.