The research reported in this thesis focuses on Late Cretaceous and Cenozoic fossil brachiopods of Western Australia. Although the work is primarily taxonomic, it also includes biodiversity, distribution and some aspects of ecology of the brachiopods described.The most recent information on the anatomy, physiology and ecology of brachiopods is summarised at the beginning of the thesis.Identification of brachiopods is determined primarily on internal morphological features as brachiopods tend to be homomorphic, many species looking externally the same. The morphological features used in the identification of the brachiopods described within the thesis are defined.The fossil material studied has come from four sedimentary basins in Western Australia. The Carnarvon Basin contains Late Cretaceous and Cenozoic fossil material. The Perth Basin also has Late Cretaceous and late Cenozoic brachiopods The Bremer and Eucla Basin have Cenozoic deposits. The stratigraphy of the deposits containing the brachiopods is described.Until this study commenced, eight species had been described from Western Australia. This thesis describes fifty eight species including thirty new species, one new family and two new genera.In preparing descriptions of the new species it become evident that many of the species from the Southern Hemisphere were quite different to those found in the Northern Hemisphere. Their closest affiliation was with genera and species described from the Antarctic Peninsula. Four genera and one species from the Late Cretaceous deposits of Western Australia are common to the Late Cretaceous deposits of the Antarctic Peninsula. In the examination of the Tertiary material from the Carnarvon Basin, it also became clear that there was a strong correlation with Tertiary material from the Antarctic Peninsula. At least four genera are common to both deposits. Six brachiopod ++ / genera from the Middle Miocene deposits of the South Shetland Islands Antarctica are common to New Zealand. Nine genera, identified from the La Meseta Formation, Seymour Island, Antarctic Peninsula, are also common to New Zealand. These genera are also found in Australia. This evidence has led to the proposal that in the Late Cretaceous there was a common shelf environment from the Antarctic Peninsula to the north-west coast of Western Australia. In this area, which formed the high latitude southern circum-Indo-Atlantic faunal province, brachiopods evolved different genera and species than those in the northern hemisphere. Many then dispersed into northern areas of the Indian, Atlantic and finally Pacific Oceans.When the material from the Middle to Late Eocene of the Bremer and Eucla Basin was examined, five genera were found to be common to the Early Tertiary of the Carnarvon Basin. When comparing the species from the south-western basins and those from the south- east it was evident that similar species occur in the Middle to Late Eocene of the Bremer, Eucla, St Vincent and Murray Basins. There are some fifteen species in common. Many of these species then occur in the Late Oligocene south-eastern basins near Victoria and Tasmania as the gap between the Australia mainland and Tasmania began to open. One species that occurs in the Late Eocene of Western Australia is also described from the Late Oligocene of New Zealand.In considering the distribution of the Cenozoic brachiopods, genera first appear in the north-west of Western Australia and they then appear in chronological order in the south-western basins and south-eastern basins of South Australia, then the south-eastern basins of Victoria and Tasmania and then New Zealand. By the Late Eocene, there was a shallow marine connection between the Bight and the Tasman Sea. By the Late Oligocene this had widened and ++ / Australia was finally totally separated from Antarctica.The Proto-Leeuwin Current was responsible for the distribution of the brachiopods from the north-west of Western Australia to the southern coast. Possible mechanisms for the distribution of genera to New Zealand include rafting and an extended larval stage.It has been suggested that brachiopods in Australia are distributed according to the substrate on which they settle rather than any other factor. Using the information on the distribution of brachiopods in Western Australia throughout the Cenozoic this hypothesis is examined. It is suggested that avoidance of light in the photic zone and food availability with competition with bivalves are more important factors than substrate conditions.

It has been proposed that geochemical and biomolecular palaeontological information can be obtained from biomineral associatedli pids. The location of lipidic material within the inorganic structureo f molluscan shells has previously been unknown, with important implications for long term survival of lipids and post-depositional contamination from the environment. Discrete experimental stages have been investigated and the different mechanical and chemical methods combined for the removal of contaminating material prior to the release and analysis of surficial, intercrystalline and intracrystalline lipids. Three extraction protocols have been compared using Recent Patella vulgata shells. Sequential stages of cleaning and extraction treatments identify n-alkanes, cholesterol (free and bound) and bound fatty acids. The n-alkanes are indigenous to the shell, but laboratory contamination can be significant, and highlights the need for experimental blanks. Bound fatty acids are extracted from intercrystalline and intracrystalline fractions. Cholesterol is extracted throughout the sequential methodology. The extraction of these compounds after extensive cleaning treatments illustrates the protective role of the inorganic biomineral. An experimental protocol for sequentially extracting protected lipids from the shells of Recent molluscs has been tested to distinguish the indigenous shell lipids from laboratory contamination and postdepositional ingress. The use of a calcium carbonate blank reveals the phthalate plasticisers extracted from the shells are due to laboratory contamination. Pristane, phytane and free fatty acids were rarely extracted which limits their use for interpretation. The n-alcohols, bound fatty acids, ß-hydroxy fatty acids, cholesterol and other steroids are extracted from the shells in higher yields than the calcium carbonate blanks and are considered indigenous to the shells. Multivariate statistical analysis is used to compare the distributions of bound fatty acids and steroids extracted from different shell locations with the reported fatty acids and steroids for the soft tissues of the same species. The reported values for the soft tissues were used to indicate the original shell lipid composition. The shells lack the unsaturated bound fatty acids reported in the soft tissues. The saturated bound fatty acids of Littorina littorea shells also differ in the carbon number distributions to the reported saturated fatty acids of the soft tissues. Surficial shell extracts are characterized by steroidal ketones, representing sterols which have been oxidised by the cleaning treatments used. The steroids from both intercrystalline and intracrystalline shell locations in Littorina littorea are most similar to the soft tissues. However, the intercrystalline steroids are different to the intracrystalline steroids which may indicate a different original composition. Potential Class level phylogenetic differences between the shells of Recent molluscs are revealed by their steroidal and bound saturated fatty acid compositions. The bivalves (n=3) have bound saturated fatty acids with a carbon number maximum of C16 whilst the gastropods (n=8) have a maximum of C16 or C18 and exhibit higher yields. ß-hydroxy fatty acids may indicate phylogenetic differences below the Class level for the Gastropoda. Principal component statistical analysis of the shell steroidal composition indicates differences at the Class level. Steroidal markers indicating the dietary intake have been found in the shells. The application of a methodology for the sequential extraction of lipids from molluscan shells has been used in a preliminary analysis of shell material for the presence of hydrocarbon pollutants. The shell nalkanes require comparison of carbon number distributions and yields with an experimental calcium carbonate blank to ensure indigeneity. Different n-alkane distributions within two Artica islandica shell samples are attributed to the different sampling locations. Differences between Patella vulgata and Littorina littorea shells from the same environment have also been observed, indicating different n-alkane uptake by different species. Polyaromatic hydrocarbons and sterane biomarkers reported to be present in the soft tissues of Patella vulgata exposed to the Braer oil spill have been searched for in the shells of an exposed sample. These compounds have not been detected. No increase in the shell n-alkane yields or similarity in carbon number distribution with the spilt oil is observed. This suggests no hydrocarbon incorporation or deputation pathway into the shell. Quaternary aged mollusc shells yield n-alkanes, n-alcohols, bound fatty acids and cholesterol. These have been extracted from both intercrystalline and intracrystal line locations within the shells. When compared with the extracts from Recent shells the yields of these lipids from fossil shells are significantly lower. The n-alkanes extracted from Quaternary shells are dominated by laboratory contamination, although some indigenous intracrystalline n-alkanes have been extracted. The bound fatty acids from intercrystalline sites within the fossils maintain their carbonn umber distribution but decreasein yields with increasinga ge; no diagenetic products were observed. The previously reported phylogenetic distinctions based on the bound fatty acids betweent he gastropodsa nd bivalves are maintainedf or fossils. However,t he information obtained from this analysis is limited by the small diversity of lipid distributions found in these fossil shells.

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The Castle Hayne Limestone (Middle Eocene, North Carolina), noted for its diverse macro-invertebrate fossils, was sampled to assess if early Cenozoic brachiopods from eastern North America record any traces of biotic interactions. Systematic surveys of two North Carolina quarries yielded 494 brachiopods, dominated by one species: Plicatoria wilmingtonensis (Lyell and Sowerby, 1845). Despite subtle variations in taphonomy, taxonomy, and drilling patterns, the two sampled quarries are remarkably similar in terms of quantitative and qualitative paleoecological and taphonomic patterns. Ninety-two brachiopod shells (18.6% specimens) contained a single circular hole. Majority of drillholes were singular, perpendicular to shell surface, and drilled from the outside. In addition, ventral valves were drilled slightly more frequently than dorsal ones and larger brachiopods contained more drillholes than smaller ones. However, the size of drillholes did not correlate with the size of brachiopods. The drillholes record "live-live" biotic interactions, which may represent either predatory attacks or parasitic infestations or combination of those two types of interactions. A notable fraction of specimens bears multiple drillholes, which is consistent with either parasitic nature of interactions or frequent failed predatory events. Drilling frequency was high in both quarries (24.5%); this high frequency reinforces other recent reports (from other continents and Cenozoic epochs) that drilling organisms may be a frequent predator or parasite of brachiopod prey or hosts. The number of case studies reporting high frequencies of drilling in brachiopods is still limited and thus insufficient to draw reliable generalizations regarding the causes and consequences of these occasionally intense ecological interactions. / Master of Science

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L'utilisation des compositions isotopiques en Mg des carbonates marins peut permettre l'étude du cycle biogéochimique de cet élément. Ainsi, les carbonates sont susceptibles d'enregistrer la composition isotopique de Mg de l'océan lors de leur précipitation. Cependant, il est nécessaire de comprendre les facteurs environnementaux (e.g. température, pH, Mg/Ca de la solution) qui peuvent contrôler ces compositions. Le premier objectif de cette thèse a donc été de déterminer les paramètres pouvant impacter les compositions isotopiques de Mg des carbonates par des précipitations expérimentales en conditions contrôlées. Il a ainsi été mis en évidence, dans les gammes considérées, mais qui restent restreintes, l'absence de contrôle de la température, du pH et du Mg/Ca de la solution sur le fractionnement isotopique du Mg lors de la précipitation des carbonates. Le fractionnement isotopique du Mg entre la solution et la calcite, à l'équilibre, a été évalué à -2,13 ± 0,24 pour mille (2sigma) à partir de cette étude, combinée à des données de la littérature. Ces résultats ont ensuite été appliqués à l'étude des compositions isotopiques de Mg dans des coquilles de brachiopodes à la fois modernes et anciens. Pour cela, une quantification des effets vitaux vis-à-vis des isotopes du Mg lors de la croissance du brachiopodes a été réalisée. Ainsi, les zones en équilibre isotopique pour Mg, O et C et donc susceptibles d'être utilisables lors des reconstructions paléoenvironnementales sont situées au sein de la calcite interne sur les bords de la coquille. Les premières mesures des compositions isotopiques de Mg sur les derniers 60 Ma suggèrent des variations de la composition isotopique du Mg de l'océan qui pourraient être liées à un changement du flux de carbonate à l'océan / Studying the Mg isotopic composition in marine carbonate can help to understand the biogeochemical cycle of this element. Indeed, carbonates may record seawater Mg isotopic composition during their precipitation. However, it is necessary to understand the possible control of some environmental factors (e.g. temperature, pH, Mg/Ca of the solution) on those compositions. Therefore, the first goal of this thesis was to determine parameters impacting carbonate Mg isotopic composition with experimental precipitations under controlled conditions. Thus, it has been shown, in restricted ranges, that temperature, pH and solution Mg/Ca have no influence on Mg isotopic fractionation during calcite precipitation. Equilibrium Mg isotopic fractionation between solution and calcite has been evaluated to -2.13 ± 0.24 per thousand (2sigma) from this study, combined with published data. These results were then applied to a study of Mg isotopic compositions in modern and past brachiopod shells. For this, a quantification of vital effects with respect to Mg isotopes during the brachiopod growth was realized. The zones in isotopic equilibrium for Mg, O and C, and thus susceptible to be used for paleoenvironnemental reconstruction, are in the inner calcite at the edge of the shell. The first measurements of Mg isotopic compositions for the last 60 Ma suggest variations of Mg isotopic compositions of the seawater which could be linked to changes of carbonate flux in the ocean

An organism's body size entails both physiological and ecological costs. Furthermore, as a parameter in analyzing organisms, it represents a fundamental and essential morphometric character. Reductions in size following mass extinction is a commonly observed phenomenon in the fossil record. This study examines the evolutionary significance of this phenomenon termed the: 'Lilliput Effect' by proposing that it represents a rapid evolutionary response to altered selection pressures during a mass extinction. This primary hypothesis is evaluated against two additional hypotheses of size reduction: 1) stunted growth as a response to stressed ecosystems, and/or 2) mass extinctions are size selective. These hypotheses were tested using data from shell size measurements and morphology primarily from molluscs and brachiopods from both North America and Denmark.. Morphological differences were evaluated using Elliptical Fourier Analysis (EFA) of outline shape in conjunction with Principle Components and Canonical Variate Analysis. The first part of this study provides a detailed methodology for data collection and analysis. New methods were developed which display promise in improving the degree to which differences and similarities in shape can be elucidated using EFA. These methods were then employed to test hypotheses of morphological change through minor events of local significance in the Florida Neogene and following the K/Pg mass extinction. Data sources for the K/Pg mass extinction were from high resolution (10 cm intervals) collection of bulk samples from the Brazos River in Texas as well as reposited museum specimens for the Braggs locality in Alabama and Danish samples. Study of size and evolution through more minor local events in the fossil record entailed measurements and shape analysis of left valves of bivalves from the genus Chine. Various environmental changes occurred at variousmpoints during the Neogene in Florida Neogene, most profoundly documented during the Plio-Pleistocene with accompanying faunal turnover. TheChione specimens analyzed were derived from a discontinuous sequence encompassing ~18 Ma and represent material from the Miocene Chipola Formation through to the Recent. The size of Chione increased from the Miocene to the Pliocene and then decreased from the Pliocene into the Pleistocene possibly due to lower primary productivity. The later part of the Pleistocene into the Recent was characterized by increased size relative to the early Pleistocene and size was stable through this interval. Morphologically, Chione changed in shape from the Miocene to the Pliocene, but remained in stasis from the Pliocene to the Recent suggesting that stabilizing selection may work well during periods of rapid, minor, environmental perturbations. There were a number of global changes occurring within the late Maastrichtian pr and the results of size measurements of molluscs demonstrate a decrease in size prior to the K/Pg mass extinction in Texas likely in response to a number of global scale events occurring towards the close of the Cretaceous that was also associated with morphological evolution in the small bivalve Breviarca webbervillensis. Paleocene material from Texas was dominated by smaller, newly evolved allochthonous grazing gastropods. These gastropods are thought to be newly evolved lineages as their first occurrence is marked in the Paleocene. Smaller sized nuculid bivalves were also a prominent feature in the Texas Paleocene and showed a rapid size beginning 40 cm above the boundary clay. At Braggs, Alabama, two groups, gastropods and oysters showed decreases in size across the boundary, and these changes are most likely a product of animpoverished Paleocene ecosystem. The pectinids were the only group of bivalve mollusc to xii reduce in size following extinction in Denmark most likely in response to a reduction in bryozoan substrate which resulted in a very soft coccolith-derived mud substrate in the mass extinction's aftermath. Size measurements from the Danish brachiopods showed reductions in size across the boundary in all genera except Rugia. There was a marked size reduction in specimens from the upper Maastrichtian at Stevns Klint as compared to the lower Maastrichtian at Mons Klint. The reasons for this are most likely due to lower temperatures at Stevns based on isotope data as well as lower productivity evidenced by lower δ13C values. There was a change in morphology for Terebratulina chrysalis in the earliest Paleogene due to shifted selective pressures favoring increased surface area as an adaptation to softer substrates. Size reduction within Danish sequences is evolutionary in nature as the Danian is characterized by different species within existing Maastrichtian genera and two new genera. The results of this study demonstrate that changes in body size can be a result of evolution from changing selective pressures as well as ecological perturbations. Distinguishing evolutionary forcings from ecological requires the collection and understanding of morphological data. Changes in size for Terebratulina chrysalis could have easily been interpreted as ecological were it not for morphological results showing the changes in surface area resulting from changing selective pressure. Late Cretaceous changes in climate and sea level produced observable changes in size and morphology in Breviarca webbervillensis. Potential size selectivity of the K/Pg mass extinction failed to account for any of the patterns observed in the data. Gryphaeid oysters in Denmark would have been a perfect candidate to support conclusions of size selectivity as they were the largest molluscs measured in this study and survived mass extinction.

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