The Deadwood Formation is an Upper Cambrian to Lower Ordovician succession of sandstones, shales, siltstones and limestones that blanketed central western North America during the initial Phanerozoic transgression. This transgression led to a broad, shallow epeiric sea which onlapped the Transcontinental Arch to the east and was protected on its westernseawardside by a system of carbonate platforms now exposed in the Rocky Mountains. The Deadwood Formation is mostly a subsurface unit, but several exposures exist in the northern Great Plains due to uplift by Eocene igneous intrusions. Linguliformean brachiopods were recovered from two areas: the Black Hills of South Dakota, and two subsurface cores from Alberta and Saskatchewan. Forty-five species of linguliformean brachiopods assigned to twenty-eight genera were recovered from these localities and described. Giving provisional names, one new family, Holmerellidae, one new subfamily, Neotretinae, five new genera, Amplitreta, Dianabella, Ganotoglossa, Holmerellus, and Vangaporosa, are erected and seventeen new species are described: Amplitreta cyclopis, Amplitreta elongata, aff. Anabolatreta tora, Canthylotreta parislata, Curticia pustulosa, Dianabella artemesia, Ganotoglossa leptotropis, Holmerellus convexus, Holmerellus, acuminatus, Holmerellus limbatus, Kotylotreta nupera, Linnarssonella tubicula, Opisthotreta nuda, Rhondellina albertensis, Tropidoglossa costata, Quadrisonia? sigmoidea, and Vangaporosa dakotaensis. The family Holmerellidae is distinguished by pitted larval shells and smooth postlarval shells, a feature that is unique in the Linguloidea. The composition of the new subfamily Neotretinae recognizes the evolutionary relationship of the genera Neotreta and Rhondellina, which are more closely related to each other than to any other acrotretid genera. Based on a comparison of the brachiopod assemblages with similar faunas from Australia and elsewhere in Laurentia, the sections studied are determined to be late Marjuman (early Late Cambrian) to early Sunwaptan (middle Late Cambrian) in age. The subsurface faunas provide the first biostratigraphic dates for any part of the Deadwood Formation in Canada. Faunas from South Dakota come from strata near the base of the formation and below the first trilobite occurrences, this giving a more refined age for the transgression in South Dakota. A large number of shells with perforations assumed to have been caused by predators were recovered from two localities in South Dakota, and represent the first evidence of predation of fossil lingulids. Two types of perforations were identified: round holes with sharp, non-beveled edges, and irregularly shaped holes with chipped edges. The former hole type is attributed to either steady pressure applied over time (e.g. boring) or to a swift, piercing percussive strike. The latter hole type is attributed to a smashing percussive strike with a blunt appendage. Based on criteria established by the proposed attack-mode models, various hypothetical animals are discussed as potential linguliformean predators. While the evidence for these predators is circumstantial, it indicates a more complex benthic paleoecology that had hitherto been envisaged for the Upper Cambrian.

Dans ce mémoire de maîtrise, nous allons nous intéresser au treillis Cambrian. Nous débuterons par des rappels de notions préliminaires sur les treillis, les groupes de Coxeter et l'ordre faible. Ensuite, nous présenterons le treillis Cambrian comme étant un sous-treillis du treillis faible. Puis, en considérant une congruence de treillis, nous allons démontrer qu'il peut également être vu comme le treillis quotient de l'ordre faible. Finalement, nous donnerons une représentation combinatoire des treillis Cambrian de type An. ______________________________________________________________________________

The Deadwood Formation is an Upper Cambrian to Lower Ordovician succession of sandstones, shales, siltstones and limestones that blanketed central western North America during the initial Phanerozoic transgression. This transgression led to a broad, shallow epeiric sea which onlapped the Transcontinental Arch to the east and was protected on its westernseawardside by a system of carbonate platforms now exposed in the Rocky Mountains. The Deadwood Formation is mostly a subsurface unit, but several exposures exist in the northern Great Plains due to uplift by Eocene igneous intrusions. Linguliformean brachiopods were recovered from two areas: the Black Hills of South Dakota, and two subsurface cores from Alberta and Saskatchewan. Forty-five species of linguliformean brachiopods assigned to twenty-eight genera were recovered from these localities and described. Giving provisional names, one new family, Holmerellidae, one new subfamily, Neotretinae, five new genera, Amplitreta, Dianabella, Ganotoglossa, Holmerellus, and Vangaporosa, are erected and seventeen new species are described: Amplitreta cyclopis, Amplitreta elongata, aff. Anabolatreta tora, Canthylotreta parislata, Curticia pustulosa, Dianabella artemesia, Ganotoglossa leptotropis, Holmerellus convexus, Holmerellus, acuminatus, Holmerellus limbatus, Kotylotreta nupera, Linnarssonella tubicula, Opisthotreta nuda, Rhondellina albertensis, Tropidoglossa costata, Quadrisonia? sigmoidea, and Vangaporosa dakotaensis. The family Holmerellidae is distinguished by pitted larval shells and smooth postlarval shells, a feature that is unique in the Linguloidea. The composition of the new subfamily Neotretinae recognizes the evolutionary relationship of the genera Neotreta and Rhondellina, which are more closely related to each other than to any other acrotretid genera. Based on a comparison of the brachiopod assemblages with similar faunas from Australia and elsewhere in Laurentia, the sections studied are determined to be late Marjuman (early Late Cambrian) to early Sunwaptan (middle Late Cambrian) in age. The subsurface faunas provide the first biostratigraphic dates for any part of the Deadwood Formation in Canada. Faunas from South Dakota come from strata near the base of the formation and below the first trilobite occurrences, this giving a more refined age for the transgression in South Dakota. A large number of shells with perforations assumed to have been caused by predators were recovered from two localities in South Dakota, and represent the first evidence of predation of fossil lingulids. Two types of perforations were identified: round holes with sharp, non-beveled edges, and irregularly shaped holes with chipped edges. The former hole type is attributed to either steady pressure applied over time (e.g. boring) or to a swift, piercing percussive strike. The latter hole type is attributed to a smashing percussive strike with a blunt appendage. Based on criteria established by the proposed attack-mode models, various hypothetical animals are discussed as potential linguliformean predators. While the evidence for these predators is circumstantial, it indicates a more complex benthic paleoecology that had hitherto been envisaged for the Upper Cambrian.

The Assynt District on the North West Highlands of Scotland is composed of a thrusted sequence of Cambrian limestones and quartzites, originally unconformably laid down on Archaean Lewisian gneisses and Pre-Cambrian Torridonian arkoses. Igneous activity associated with the development of the Caldedonian orogeny occurs as a series of genetically related hornblende ± pyroxene lamprophyre sills. High level fractionation of the lamprophyric magmas has resulted in the development of a suite of tinguaitic, peralkaline, oversaturated, aegirine felsites which cut the earlier lamprophyric intrusions. Plutonic activity occurs in the Assynt District, as an early syenitic intrusion at Loch Ailsh dated at 439 ± 24 my and a late, in part ultrapotassic, carbonatite bearing, undersaturated intrusion at Loch Borralan, intruded after thrusting activity had ceased at 430 ± 4 my. The lamprophyric intrusions are relatively primitive magmas having high MgO and Ni, Cr abundances, they are enriched in light rare earths. Their trace element chemistry shows that they are derived from a lithospheric mantle, metasomatically enriched with incompatible elements and volatiles from subducted crust. Textural study shows that the primitive magmas were probably intruded as a volatile rich suspension of mafic phenocrysts. Subsequent evolution initially by the fractionation of amphibole pyroxene and plagioclase has resulted in the formation of a suite of increasingly silicic andesitic to rhyolitic sills. The later stages of evolution were due to the metasomatic effects of a volatile phase. The simultaneous removal of hornblende and plagioclase has resulted in the formation of oversaturated peralkaline felsites without the REE patterns normally associated with evolved felsitic rocks. Thrusting activity has resulted in the apparent close association between the lamprophyric/felsitic sill swarm and the loch Borralan intrusion. Pre thrusting reconstruction of the Assynt district show that the sills were intruded at least 30km to the south west and are not genetically related to the Loch Borralan intrusion.

With the advent of automated sequencing, sequence data are now available to help us understand the functioning of our genome, as well as its history. To date,powerful methods such as maximum likelihood have been used to estimate its mode and tempo of evolution and its branching pattern. However, these methods appear to have some limitations. The purpose of this thesis is to examine these issues in light of Bayesian modelling, taking advantage of some recent advances in Bayesian computation. Firstly, Bayesian methods to estimate divergence dates when rates of evolution vary from lineage to lineages are extended and compared. The power of the technique is demonstrated by analysing twenty-two genes sampled across the metazoans to test the Cambrian explosion hypothesis. While the molecular clock gives divergence dates at least twice as old as those indicated by the fossil records, it is shown (i) that modelling rate change gives results consistent with the fossils, (ii) that this improves dramatically the fit to the data and (iii) that these results are not dependent on the choice of a specific model of rate change.Results from this analysis support a molecular explosion of the metazoans about 600 million years (MY) ago, i.e. only some 50 MY before the morphological Cambrian explosion. Secondly, two new Bayesian tests of phylogenetic trees are developed. The first aims at selecting the correct tree, while the second constructs confidence sets of trees. Two other tests are also developed, in the frequentist framework. Based on p-values adjusted for multiple comparisons,they are built to match their Bayesian counterparts. These four new tests are compared with previous tests. Their sensitivity to model misspecification and the problem of regions is discussed. Finally, some extensions to the models examined are made to estimate divergence dates from data of multiple genes, and to detect positive selection.

Trilobites typical of the well known Olenellus zone of the Lower Cambrian constitute a large collection from the Eager Formation, near Cranbrook, B.C. Their classification is discussed and two new species described: Olenellus eagerensis n.sp. and Olenellus schofieldi n.sp. Since the use of certain structures in classifying olenellids has been disputed in the past, these and other less controversial features are critically examined, insofar as they apply to the genera and species present. From this study the writer assembles criteria which might be used by later workers to redefine the generic and specific positions of selected species of Olenellus and Paedeumias. / Arts, Faculty of / Geography, Department of / Graduate

New specimens of the problematic group Sphenothallus have been recovered from the early Cambrian Shuijingtuo and Niutitang Formations in South China. The two sites from the Shuijingtuo Formation were collected from Yanjiahe and Changyang in Hubei and the equivalent Niutitang Formation from Siduping in Hunan. The ability to unite fossils in this genus is due to the pair of longitudinal thickenings which allow for species level analysis of morphology within this easily recognized genus. The morphology needed to differentiate species is subtle and may be influenced by abiotic factors. Differences between the three sampled sites representing different weathering states and paleo-environments allow us to investigate variations in preserved morphology related to abiotic factors (e.g., taphospecies and ecophenotypes). Despite differences in weathering and interpreted paleo-environments, no significant differences in preserved morphology are observed. Without abiotic biases, a logarithmic ontogenetic pattern of the organism indicates a set size of the adult as well as a set width of the longitudinal thickening throughout the organism's lifespan. The ability to incorporate multiple specimens from sites with differing diagenetic histories allows for greater sample sets to be created for investigating morphology, especially with early Cambrian organisms which rely on subtle character differences to identify species. / Master of Science

The Middle Cambrian Spence Shale Member of the Langston Formation of northern Utah and southern Idaho is a fossil-rich unit that exhibits distinct cyclicity at the parasequence (meter) scale. At least seven discrete, shallowing-upwards parasequences, or cycles, can be found at the Miners Hollow and Antimony Canyon localities, each composed of calcareous shale capped by limestone. Within each cycle and within the member as a whole, predictable patterns of faunal distribution are evident. Sampling and identification of fossils from two localities have revealed that observed changes in fauna track changes in sea level throughout the section. Through cluster and principal components analyses it has been determined that those rocks of the Spence Shale representing a transgressive systems tract are home to a particular community of organisms, while those rocks of the highstand systems tract are home to another. It logically follows that the rocks of the transgressive tract represent a distinct biofacies, while those of the highstand tract represent another. The transgressive biofacies is composed of species such as agnostid and oryctocephalid trilobites and inarticulate brachiopods that are commonly found in deeper ramp settings. The highstand biofacies is distinguished by such taxa as Zacanthoides and other larger trilobite genera such as Glossopleura and Kootenia, and the eocrinoid Gogia, among others. The difference in ramp position between the Miners Hollow and Antimony Canyon localities implies a water depth gradient, with Antimony Canyon representing shallower water and Miners Hollow representing deeper water. This relationship is also reflected in the biofacies and community assignments. The stratigraphic trends explored in this study may be applied to other Spence Shale localities and possibly other Cambrian fossil deposits, such as the Burgess Shale of British Columbia. (151 pages)

Includes 5 items (fold.) in back pocket / Includes bibliographical references / 2 v. : ill. ; 30 cm. / Title page, contents and abstract only. The complete thesis in print form is available from the University Library. / Thesis (Ph.D.)--University of Adelaide, Dept. of Geology and Minerology, 1973

Includes 5 items (fold.) in back pocket / Includes bibliographical references / 2 v. : ill. ; 30 cm. / Title page, contents and abstract only. The complete thesis in print form is available from the University Library. / Thesis (Ph.D.)--University of Adelaide, Dept. of Geology and Minerology, 1973