Determination of water masses and circulation in the eastern Great Australian Bight, in conjunction with analysis of δ18O values and trace element concentrations in the articulated brachiopod Anakinetica cumingi, indicate that brachiopods faithfully record ambient temperatures and oceanographic conditions. Five water masses are identified on the shelf during March 1998, on the basis of temperature, salinity, δ2H and δ18O values. The warm, high salinity Great Australian Bight Plume occurs in the western part of the study area both at the surface and at depth, and the cool, low salinity Flinders Current flows west along the continental slope. The Flinders Current provides upwelling water along the Eyre Peninsula and in the central Great Australian Bight, and mixing of this water with Great Australian Bight Plume and shelf waters forms the combined water masses Flinders Current + Great Australian Bight outflow, Modified Flinders Current and Mixed waters. The Great Australian Bight Plume and Flinders Current are isotopically distinct, with Great Australian Bight Plume waters having lower δ18O values and higher δ2H values than Flinders Current waters. Using mean annual temperatures and δ18O values of seawater, brachiopod temperatures calculated from their δ18O values are within 1°C of measured temperatures. δ18O values in the brachiopods, in conjunction with seasonally variable temperatures and δ18O values of seawater, provide evidence for brachiopod major growth periods. Calculated brachiopod temperatures are most accurate assuming 70% of brachiopod growth occurs during summer when upwelling is occurring and 30% of growth occurs during the rest of the year. Brachiopods may be growing more during upwelling periods in response to increased food supply. Ba, Ni and V concentrations in the brachiopod shells show spatial variation that matches with water mass distribution on the shelf. Ba positively correlates with nitrate contents in the water and is enriched in brachiopods growing in upwelling areas. Ni and V positively correlate with seawater temperatures, suggesting that incorporation of these two elements into brachiopod calcite is temperature dependant. All three elements reflect the anticlockwise circulation pattern present in the eastern Great Australian Bight during the summer major growth period. / Thesis (Master, Geological Sciences & Geological Engineering) -- Queen's University, 2009-01-29 16:23:44.036

No description available.

The fossil record is the primary source of information on the history of life. As such, it is important to understand the limitations of this record. One critical area in which there is still much work to be done is in understanding how the fossil record, and our interpretation of it, may be biased. Herein, the fidelity between the life and death assemblage of an extant brachiopod with respect to morphological variability is studied using geometric morphometrics. The results from several analyses confirm a high degree of morphological variability with little change in mean shape between the living and sub-fossil assemblage. Additionally, there is no evidence of distinct morphogroups in either assemblage. These trends persist at all depths and size classes indicating that this species could be recognized as a single, rather than multiple, species if only fossil data were available. The second chapter involves the recognition and quantification of a worker bias in monographs of brachiopods and bivalves. Most specimens studied came from the 65th to 69th percentile of their species' bulk-collected size-frequency distribution. This indicates a significant bias toward monograph specimens that are larger than the mean size of the bulk sample. When compared at the species level, this bias was found to be highly consistent among the 86 species included in the study. Thus, size measurements of monographed specimens reliably and consistently record a similar size class for any given species, and this bias is easily corrected during meta-analyses. Chapter three focuses on bivalves and brachiopods from a modern tropical shelf and quantifies the magnitude of time averaging (temporal mixing) for these two different organisms. This is accomplished by dating a suite of shells from each site using amino acid racemization calibrated with several radiocarbon dates. By studying the age distributions for each species it is determined that, despite some site to site differences, both bivalve and brachiopod species exhibit a similar time averaging magnitude when collected from the same region or depositional system. This indicates that fossil assemblages of these species may have very similar resolution. / Ph. D.

Drilling predation presents a rare opportunity to quantify ecological and evolutionary interactions in the fossil record. To date, most of this research has been done on Late Mesozoic and Cenozoic deposits, and large-scale studies have focused on temporal rather than spatial patterns. However, drilling predation occurs throughout the entire Phanerozoic, and patterns in spatial variability may mask secular trends. These issues are addressed in a series of projects presented here. An extensive survey of museum specimens and bulk materials indicate that drilling predation in Late Paleozoic brachiopod prey is relatively rare (<1% of fossil specimens are drilled) but widespread and continuously present. The intensity of drilling predation on Late Paleozoic bivalve mollusks (this is the first quantitative report of this kind) is much higher than that seen for contemporaneous brachiopod prey, but lower than what is common for Late Mesozoic and Cenozoic mollusks. Drilling intensity varies significantly between taxa and across localities, (e.g., a sample of the Pennsylvanian brachiopod Cardiarina cordata produced an estimate of 32.7%, which is an intensity similar to that seen in Cenozoic mollusks and the highest yet reported for any brachiopod). However, data for the brachiopod genus Composita, which appears to be a preferred brachiopod prey in many Late Paleozoic assemblages, show that although this genus is subject to drilling predation continuously throughout its geologic range, the over all intensity is very low (less than 1%) and at no time does the intensity ever exceed 10%. Spatial variation in Miocene assemblages from Europe is shown to be on the same order as temporal variation throughout the Cenozoic. Significant variation in drilling intensity is also documented for the Paleozoic. This emphasizes the point that to fully understand patterns of predation through time, both spatial and temporal distribution must be considered. / Ph. D.

New brachiopod materials from the lower Cambrian (Global Stage 3 and lower Stage 4) of Esmeralda County, Nevada are described and their age distribution and diversity is discussed. The specimens originate from the Fritzaspis, “Fallotaspis”, “Nevadella” and Bonnia-Olenellus biozone which in the area correspond to the Campito Formation and the overlying Poleta Formation. As the specimens from the Gold Coin Member (Begadean Series) and the Montenegro Member (Waucoban Series) of the Campito Formation encompass the oldest samples, they were therefore prioritised as there was not enough time to describe all the specimens. The oldest known trilobites from Laurentia have previously been reported from the Gold Coin Member and it is of interest to determine if the brachiopods from the same member also are the oldest known from Laurentia.As many specimens are poorly preserved, especially the ones from coarse siliciclastic intervals, the determination of their systematic position is somewhat aggravated. Despite this, a diverse fauna including Lingulida, Obolellida, Naukatida, Kutorginida, Orthida and stem-group brachiopods have been successfully identified. A total of 16 taxa were noted for the Campito fauna, including the problematic and rare genera Swantonia and Spinulothele but unfortunately little new information could be gained regarding the characters for these rare genera. Four genera are reported for the first time from the area, not including material described under open nomenclature. / Under den geologiska tidsåldern Kambrium (542-488 miljoner år sedan) uppträder de första fossilerna av djurgruppen brachiopoder, eller armfotingar som de också kallas, tillsammans med många andra djurgrupper. Få platser i Laurentia (paleo-kontinent bestående av nutidens Nordamerika och Grönland) finns kvar som har bevarat de tidigaste förekommande brachiopod fossilerna. Esmeralda län i Nevada är en sådan plats och det här har det även spekulerats att Laurentias absolut äldsta brachiopod fossil skulle kunna hittas där. Denna avhandling fokuserar på att studera dessa brachiopod fossil från Nevada. När åldern för de äldsta studerade brachiopoderna (Begadean I ålder) i denna avhandling jämfördes med tidigare dokumenterade åldrar för äldre lägre Kambrium brachiopod fossiler stod det klart att dessa är de äldsta brachiopod fossilerna som hittats hittills.Många nya fossil prover har samlats in av J.S. Hollingsworth under en längre tid från Nevada och beskrivs häri. De nya fossilen innefattar både sällsynta släkten, så som Swantonia samt Spinulothele, och släkten som inte har hittats i Esmeralda län tidigare. Tyvärr erhölls lite ny information beträffande de sällsynta släktenas morfologiska egenskaper. Upptäkterna om de nya släkterna i området skulle kunna hjälpa oss att bättre kunna rekonstruera brachiopod faunan från Nevada samt att förstå spridningen av olika brachiopod grupper i framtiden.

No description available.

No description available.

An accurate understanding of global patterns through geologic time depends upon multi-scale analyses of spatial variation within narrow temporal intervals. This work investigates geochemical and paleoecological patterns in modern brachiopod faunas which may serve as analogues for ancient brachiopod assemblages. The paleoclimatic utility of delta18O in the phosphatic phase of lingulid brachiopod shells requires valve secretion in equilibrium with seawater, an assumption tested (and rejected) when analyzed at scales ranging from millimeters to kilometers. By contrast, biological encrustation of the brachiopod fauna of the Southeast Brazilian Bight shows strong sensitivity to microenvironmental conditions such as host identity, shape, and size, and may prove useful for studies of ancient planktonic productivity. Comparison of encrustation patterns on naturally occurring brachiopods and bivalves collected from the same sites, and occupying the same size range, demonstrates that the results of encrustation studies on modern bivalves cannot be directly applied to ancient brachiopods. However, careful comparisons may reveal patterns of epibiont selectivity and the impact of changes in the relative abundance of host shells through geologic time. Finally, neither epibiont abundance nor diversity increase with host age as indicated by dated brachiopod shells from the past 1000 years. These results suggest that the temporal resolution of epibiont assemblages matches their spatial resolution, and strengthen evidence for competition among encrusting taxa. By documenting geochemical and paleoecological variation within shells and across a continental shelf, this work demonstrates the importance of understanding spatial variation across all scales before interpreting trends through time. / Ph. D.

<p>The Superfamily Strophomenoidea is a very diverse group of brachiopods in the Early Palaeozoic. In the Silurian succession on Gotland, they are among the most easily identifiable, and commonly found fossils. However, there are few detailed studies of this group from Gotland, and no new strophomenide taxa have been described from this area since 1869. The life habits of strophomenides are also poorly understood, partly because their morphology differs greatly from that of living brachiopods. </p><p>The succession on Gotland yielded 27 species belonging to the Strophomenoidea, of which two species and two subspecies are new. The remaining species have been described earlier from Gotland or Great Britain. The most important group is the Leptaeninae, which occurs commonly throughout the entire succession on Gotland. Five species (one new), two new subspecies and two taxa treated under open nomenclature were found. <i>Leptaena rhomboidalis</i> and <i>Lepidoleptaena poulseni</i> were specialized for life in shallow water environments, retaining a large apical pedicle; the remaining leptaenines were ambitopic. The Furcitellininae is represented by three genera comprising six species, of which only one persisted into the Ludlow. All were ambitopic, except <i>Pentlandina loveni</i>, which was specialized for high-energy environments. Six species of “strophodontids” from Gotland, belonging to the Leptostrophidae, the Strophodontidae and the Shaleriidae, share a shallow-bodied, variably concavo-convex shell with costellate ornament. <i>Mesoleptostrophia</i> and <i>Brachyprion</i> (<i>Brachyprion</i>) were long-ranged and ecologically tolerant, while <i>B.</i> (<i>Erinostrophia</i>), <i>Strophodonta</i> and <i>Shaleria</i> had short ranges and were ecologically specialized. The two earliest known cementing strophomenides occur on Gotland, and their hitherto unknown dorsal valves have been identified: <i>Liljevallia </i>was found to belong to the Douvillinidae. The cementing <i>Leptaenoidea silurica</i> was found to be conspecific with the ambitopic <i>Scamnomena rugata</i>; it was able to live ambitopically if removed from the substrate. The thickened dorsal valves allow reconstruction of its lophophore.</p>

The Superfamily Strophomenoidea is a very diverse group of brachiopods in the Early Palaeozoic. In the Silurian succession on Gotland, they are among the most easily identifiable, and commonly found fossils. However, there are few detailed studies of this group from Gotland, and no new strophomenide taxa have been described from this area since 1869. The life habits of strophomenides are also poorly understood, partly because their morphology differs greatly from that of living brachiopods. The succession on Gotland yielded 27 species belonging to the Strophomenoidea, of which two species and two subspecies are new. The remaining species have been described earlier from Gotland or Great Britain. The most important group is the Leptaeninae, which occurs commonly throughout the entire succession on Gotland. Five species (one new), two new subspecies and two taxa treated under open nomenclature were found. Leptaena rhomboidalis and Lepidoleptaena poulseni were specialized for life in shallow water environments, retaining a large apical pedicle; the remaining leptaenines were ambitopic. The Furcitellininae is represented by three genera comprising six species, of which only one persisted into the Ludlow. All were ambitopic, except Pentlandina loveni, which was specialized for high-energy environments. Six species of “strophodontids” from Gotland, belonging to the Leptostrophidae, the Strophodontidae and the Shaleriidae, share a shallow-bodied, variably concavo-convex shell with costellate ornament. Mesoleptostrophia and Brachyprion (Brachyprion) were long-ranged and ecologically tolerant, while B. (Erinostrophia), Strophodonta and Shaleria had short ranges and were ecologically specialized. The two earliest known cementing strophomenides occur on Gotland, and their hitherto unknown dorsal valves have been identified: Liljevallia was found to belong to the Douvillinidae. The cementing Leptaenoidea silurica was found to be conspecific with the ambitopic Scamnomena rugata; it was able to live ambitopically if removed from the substrate. The thickened dorsal valves allow reconstruction of its lophophore.