Based on a thorough examination of museum and field Climactichnites specimens, two species of this trace, which is restricted to North America, are recognized, each representing a unique behavioral variant. C. wilsoni represents surface-produced trackways, whereas C. youngi is re-erected for subsurface burrows. Burrowing behavior is supported by the presence of C. youngi within beds, the orientation of burrows inclined to bedding, and the presence of distinct burrow fills. Burrows are distinguished from surface traces by characteristics including the absence of lateral ridges and the presence of mm-sized striations superimposed on the trace. Burrowing behavior was previously unknown and represents a new behavior for the animal. A new ichnospecies, Musculopodus sedentarius, is erected for sedentary impressions of the animal. In the future Musculopodus may be expanded to include the resting traces of other soft-bodied animals known from fossils. Analysis of Climactichnites indicates that the trackmaker was elongate, bilaterally symmetric, dorsoventrally flattened, and soft-footed. These characteristics are consistent with the trackmaker being a primitive mollusk or mollusk-like animal. Unlike other Neoproterozoic and Cambrain mollusks, such as Matthevia, Wiwaxia, and Odontogriphus, the Climactichnites trackmaker could reach considerable size. At up to 29 cm wide and possibly 67 cm long, it was one of the largest animals of its time. During locomotion, the animal generated muscular waves along the sole of its foot, which was extended and clamped into the substrate. Contraction of pedal muscles then pulled the body forward. This method of locomotion is similar to that employed by some gastropods, including Bullia and Polinices, which make Climactichnites-like trackways in exposed intertidal settings today. However, these modern trackways are not preserved because they are eroded by wind, waves, tides and subsequent bioturbation, as experiments confirm. Abundant microbial sedimentary structures associated with Cambrian occurrences suggests that microbial binding may have mediated the preservation of Climactichnites. Two lines of evidence suggest that the Climactichnites trackmaker may have been one of the first animals to venture onto land: the co-occurrence of subaerially-produced sedimentary structures, such as adhesion structures and raindrop impressions, and trackways that span shoreline depth gradients and exhibit variable preservation quality along their length.

Twelve freshwater gastropod families, 39 genera and 70 fossil and Recent species are recognized and systematically treated. Keys to the families, genera and species were constructed and all species are illustrated. The purpose of this study was to synthesize and update the taxonomy, zoogeography, origins and correlations with drainage systems of the entire Recent and fossil freshwater gastropod fauna of Texas.

<p>Extensive bedding plane exposures in the Ludlowville shales along Cazenovia Creek Near Spring Brook, New York display the spatial distribution of the skeletal remains from a marine faunal assemblage. Fossils typically occur in aggregates that are subcircular in plan view and plano-convex in cross-section with the convex side down. A previous paleoecological study of the most abundant brachiopod, Ambocoelia umbonata (Conrad), (Bray, 1969) revealed that aggregations were in-situ 'life' associations rather than mechanical accumulations of shell debris. This conclusion suggested that fossil clusters represent short-lived ecological successions or seres and the present study was undertaken to examine the origin, development, and extinction of clusters .</p> <p>Three clusters, sampled in 10 x 10 x 0.5 cm blocks, were subjected to an exhaustive analysis. The absence of sedimentary structures, lack of internal lamination, minor amounts of silt-size quartz, pelleted thin section textures, numerous burrow traces and presence of 3 species of deposit feeding nuculanid bivalves strongly suggested a bioturbated, fluid substratum. Under these conditions fossil clusters were initiated by attaclunent of spat to scattered shell surfaces (i.e. trilobite carapaces, cephalopod shells and rooted crinoids). Successful growth of sessile invertebrates (largely brachiopods) produced continuous addition of surface area for future spat attaclunent and clusters expanded laterally while the soft bottom prevented vertical buildup faster than sedimentation rates. Fossil density distributions within samples indicated that several species had a patchy arrangement within clusters and that the dispersion pattern of two taxa, .Ambocoelia and Styliolina, altered during cluster development. Analysis of associations by presence-absence criteria revealed that specimens larger than 2 mm had few taxonomic associations near the base of clusters and many associations near the top. The number of associated taxa among specimens smaller than 0.75 mm remained constant, but there was a decrease in the number of shared associations by some taxa toward the top of clusters. Species-abundance distributions indicated no temporal change in diversity and the succession within clusters apparently did not proceed by colonization of different taxa at different times. The lack of bottom currents and the reduction of bioturbation in shell laden patches resulted in fecal concentration that created a substrate which was locally lethal. This ultimately caused failure of spat recruitment and clusters were terminated over a short period of time. </p> / Thesis / Doctor of Philosophy (PhD)

No description available.

Fossil beetle based palaeoclimatic and palaeoenvironmental reconstructions are presented from the Westport region, West Coast, South Island, New Zealand for the last glacial cycle. They include the longest continuous fossil beetle record from New Zealand, covering 16,000 years over the OIS 3/OIS 2 transition. Early last glacial (OIS 4) and mid- Holocene (OIS 1) reconstructions are also presented. The assumptions underlying fossil beetle research in New Zealand are tested indicating beetles are suitable proxies for reconstructing palaeotemperature and palaeoprecipitation. This thesis provides the first quantitative estimates of temperature and precipitation from the Westport region for the last glacial. Reconstructed temperatures indicate stadial cooling was seasonal. Maximum cooling was ca. 5℃ in winter and ca. 2-3℃ in summer. Winter cooling is consistent with previous quantitative estimates from New Zealand. Mean annual precipitation decreased a maximum 35-40% during stadials. Temperatures and precipitation varied during OIS 3/2 indicating multiple possible drivers for glaciation. A glacial advance ca. 34-28ka BP correlates with ca. 5℃ winter cooling and ca. 40% less precipitation, which supports temperature driven glaciation whereas a glacial advance ca. 24-22ka BP correlates with ca. 3℃ winter cooling and precipitation similar to present, which supports precipitation forced glaciation. Palaeoenvironmental reconstructions of stadial vegetation from the Westport region indicate lowland Nothofagus fusca-type forest during OIS 4 and a forest-grassland mosaic during OIS 3/2. These records contrast with pollen-based reconstructions of a treeless landscape in Westport during stadials but are consistent with quantitative estimates of stadial cooling. A shift of reproductive strategy in arboreal vegetation may explain the lack of tree pollen in stadial pollen records. This is significant for our understanding of glacial palaeoecology and palaeoclimatology as pollen records may not accurately represent stadial vegetation.

タンデトロン加速器質量分析計業績報告

The Main Karoo Basin of South Africa is renowned for its exceptional palaeontological record and while its vertebrate fossils have been extensively researched, Karoo floras have received considerably less attention. Poor yields of palynomorphs from the Beaufort and “Stormberg” groups have complicated the task of erecting a comprehensive palynozonation scheme for the Karoo Supergroup. For this study, 65 palynologically productive samples from the Dwyka, Ecca, Beaufort and “Stormberg” groups allowed for systematic descriptions of all palynomorphs, as well as the ranges of the different taxa through the entire Karoo stratigraphic succession. Taxa with restricted ranges are useful for biostratigraphic correlation and these palynomorphs were used to delineate microfloral zones for the Karoo basin. The Dwyka Group contains high numbers of acritarchs and is generally low in species diversity. Useful biostratigraphic taxa for the Ecca Group include Cannanoropollis, Hamiapollenites, Platysaccus and Striatopodocarpites. Aratrisporites is a marker for the Latest Permian / Early Triassic Beaufort Group, while Cyathidites, Dictyophyllidites, Equisetosporites and Uvaesporites are indicators of the Late Triassic / Early Jurassic “Stormberg” Group. Palynostratigraphic zones correlate largely with the Karoo vertebrate biozones and severe and sudden extinction events are recognised among Karoo palynomorphs in the upper Tapinocephalus and Dicynodon assemblage zones. The first comprehensive palynological biozonation scheme for the Main Karoo Basin is proposed and the study provides a broad overview of Gondwanan Carboniferous - Jurassic floras. This study demonstrates that palynology is useful in correlating age equivalent lithostratigraphic units in the proximal and distal sectors of the Karoo Basin. Microfloras from previous South African studies are integrated within the proposed palynostratigraphic scheme, and palynological signatures of the various Karoo formations are shown to be consistent. Despite the constraints of floral provincialism, South African microfloras can be correlated to selected Gondwanan biozonations from Australia, Africa, Antarctica, New Zealand and South America. Future studies should focus on sampling more intensively over smaller stratigraphic intervals, which will assist in the correlation of time equivalent lithostratigraphic units in the different sectors of the basin, thus aiding in refinement of basin development models. Key words: palynology, Karoo, vertebrate biozones, stratigraphy, Gondwana

Thesis advisor: Paul Strother / The Rogersville Shale of the Middle to Late Cambrian Conasauga Group was deposited on the margins of Laurentia, in what is now eastern Tennessee. Based on 21 thin section samples from the ORNL-Joy2, core five distinct microlithofacies are described, trace fossils characterized, and palynological data interpreted. This investigation concluded that the Rogersville Shale was deposited in a shallow, restricted marine or possibly estuarine environment that would have been exposed to terrestrial runoff. Previous work on the Conasauga Group placed deposition of the Rogersville Shale within an intercratonic basin in approximately 250m of water, perhaps significantly deeper. This investigation found that the Rogersville Shale was likely deposited in a lagoonal setting or restricted estuarine environment that had freshwater input. / Thesis (MS) — Boston College, 2008. / Submitted to: Boston College. Graduate School of Arts and Sciences. / Discipline: Geology and Geophysics.

Troodontidae is an important dinosaur taxon that closely resembles birds in both morphology and biology. The evolution of troodontids is crucial for understanding evolutionary transitions between non-avialan theropods and avialans. Despite the recent discovery of several troodontid taxa across the world and many new studies of coelurosaurian relationships, an overall survey of morphological variation in troodontids and a comprehensive analysis of ingroup troodontid relationships have yet to be accomplished. In the first four chapters of this dissertation, the osteology of two new troodontid taxa and two closely related paravians are described in detail. These descriptions are based on new specimens recovered from the Mesozoic of China and Mongolia. These new taxa include the basal dromaeosaurid Microraptor zhaoianus, the basal avialan Anchiornis huxleyi, a new troodontid taxon represented by IGM 100/1323, and a second new troodontid taxon represented by IGM 100/1126 and IGM 100/3500. These paravian taxa are all small-sized, with a basal paravian body plan resembling Archaeopteryx, yet they represent members of all three major paravian lineages (Troodontidae, Dromaeosauridae and Avialae), and support the traditionally recognized paravian interrelationships. Osteological description of Microraptor zhaoianus is based on an excellently preserved new specimen BMNHC PH881. This specimen preserves significant morphological details that are not present, or are poorly preserved, in the other Microraptor specimens, including aspects of the skull, rib cage, and humerus. These new characters corroborate Microraptor as a member of the Dromaeosauridae and support the close relationship of troodontids with dromaeosaurids. Four new specimens (PKUVP 1068; BMNHC PH804, BMNHC PH822 and BMNHC PH823) of Anchiornis huxleyi reveal new osteological details of this important paravian taxon. Anchiornis huxleyi shares derived features with avialans, but it lacks derived deinonychosaurian characteristics such as a laterally exposed splenial and a specialized raptorial pedal digit II. IGM 100/1323 represents a new troodontid taxon from the Late Cretaceous Djadokhta Formation of Mongolia, diagnosed from other troodontids by the absence of the lateral groove on the dentary, a posteriorly curved pterygoid flange, a distinct spike-like process on the ischium, and elongate chevrons. Despite generally having a basal paravian body plan, IGM 100/1323 displays many derived troodontid features. IGM 100/1126 and IGM 100/3500 represent another new Late Cretaceous troodontid taxon from the Djadokhta-Formation-like rocks at Ukhaa Tolgod, Mongolia. It is unique and distinct from other troodontids in having closely packed peg-like teeth, a twisted suborbital process of the jugal, a quadratojugal with a crescentic ascending process that braces the quadrate posteriorly, reduction of the basal tubera, and presence of a posterior fossa on the proximal fibula. This new taxon is morphologically more derived than Early Cretaceous troodontids but is more primitive than other Late Cretaceous troodontids. A new and comprehensive phylogenetic analysis of coelurosaurian theropods, focusing on troodontids is presented in Chapter 5. This is an updated version of the Theropod Working Group (TWiG) analysis (2015.1). This new analysis incorporates new paravian taxa and new characters, most of which are relevant to paravians, especially the troodontids that are the focus of this dissertation. The new phylogenetic analysis agrees with previous studies on the general relationships of coelurosaurians, yet some important differences from previous TWiG analyses are present in paravians, including: 1), the Jianchang paravians are recovered as basal avialans; 2), Late Cretaceous troodontids form a monophyletic group; and 3), Jinfengopteryginae is not monophyletic.

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