Ordovician samples have been collected from various places from within three separate terranes in Scotland; the Highland Border Complex, the Southern Uplands and the Midland Valley. The samples have been palynologically processed and their assemblages studied with the aim of understanding some of the palaeoecological, biostratigraphical and thermal relationships of the three areas.Seventy one samples have been processed from nine localities of the Highland Border Complex and these have yielded fifteen species of chitinozoans in four genera, as well as indeterminate species of those genera. There are also five species of acritarchs in four genera as well as other microfossils. Black shales from the Complex yield the most diverse palynomorph assemblages, and were probably deposited from Arenig through to Caradoc although not necessarily at the same time in different parts of the basin. The preservation of palynomorphs appears to be better in the west of Scotland than in the east.From the Southern Uplands samples have been processed from Coldingham Bay and proved barren, from Barrhill the assemblages are poor, but from the Ordovician-Silurian bondary beds (C. peltifer to P. acuminatus Zones) at Dob's Linn they are quite diverse although abundance is very low, with forty three samples yielding thirty three species of acritarchs in eighteen genera, thirty one species of chitinozoans in thirteen genera and various other microfossils. The boundary cannot be delineated using the palynological assemblages, and although Tylotopalla sp. A and Ancyrochitina ancyrea Eisenack 1931 are common in most of the samples from the boundary the palynomorphs do not appear to mirror the changes that occur in the graptolite assemblages.From the Midland Valley samples have been processed from eight miscellaneous localities in the region of Girvan, giving very little biostratigraphical data, although one sample from Doularg Hill is dated as upper Arenig to lower Llanvirn. A section of twelve samples processed from the Mill and Shalloch Formations (D. complanatus and D. anceps Zones) at Woodland Point, Girvan, has yielded thirty five species of chitinozoans in twelve genera including a new species Angochitina woodlandensis and five new combinations; Belonechitina comma (Eisenack 1959), Belonechitina hirsuta (Laufeld 1967). Belonechitina micracantha (Eisenack 1931), Belonechitina schopfi subsp. americana (Taugourdeau 1965), and Belonechitina seriespinosa (Jenkins 1969). There are also forty seven species of acritarchs in twentyone genera, including two new species; Actinotodissus woodlandense, and Goniosphaeridium girvanense, and many scolecodonts. Spores are common and three species are recognised at Woodland Point. The samples are dated as Upper Ordovician and Calpichitina lenticularis (Bouche 1965) and Acanthochitina barbata appear to be important Upper Ordovician indicators, possibly being near-shore species as they are not found in rocks of the same age at Dob's Linn. Calpichitina lenticularis is very important in one sample and less so in all the others and it is suggested that it may be reworked. The palaeoecological picture at Woodland point shows an offshore situation in the Mill Formation, becoming more near-shore at the base of the Shalloch Formation and then more off-shore again.The palaeoecology of both Dob's Linn and Woodland Point are discussed and chitinozoans found to be more common in black shales than grey mudstones, although the acritarchs do not appear to be preferentially found in grey mudstones or black shales. Netromorph acritarchs are less common at Dob's Linn than was expected, but are very common at Woodland Point which may suggest that the sediments at Woodland Point were deposited more offshore than those at Dob's Linn but were more greatly influenced by turbiditic material. Sphaeromorph acritarchs at Woodland Point are very common and due to the variable thickness of the walls it is suggested that there is a mixing of near-shore and off-shore species, possibly by the turbiditic action mentioned above. Belonechitina is markedlymore important at Woodland Point than at Dob's Linn the reverse of which is true with Cyathochitina . The suggested reason for this is that Belonechitina is a near-shore species whilst Cyathochitina is an off-shore species. Veryhachium appears to become more important towards the end of the Ordovician, as a sample each from Woodland Point and Dob's Linn contain three species of this relatively rare genus, although the significance of this is not yet known.The sample from Dob's Linn and Woodland Point are compared with published works using the jacquard Coefficient and the results presented. The samples at Dob's Linn are compared with the Ordovician-Silurian boundary sediments elsewhere, and although different species are present at Dob's Linn and on Anticosti Island, and the abundance and diversity is lower at Dob's Linn, the boundary in Scotland has a much better palynomorph assemblage than was expected. The boundary assemblage presented here is quite similar to the one in Skane, Sweden.Finally the thermal history of the samples is discussed, and a general trend appears, with the samples from Girvan being the least altered, those from the Southern Uplands being moderately altered and finally the Highland Border Complex samples which have been subjected to temperatures probably between 200 and 300oC, and thus strongly altered.

Oxbow lakes are of high ecological importance due to the number and the diversity of habitats they provide. They are created after the abandonment of meanders and subsequent sediment infilling leads to their progressive terrestrialisation, taking from a few months up to several centuries. Nonetheless, little is known about oxbow lake terrestrialisation processes, sediment composition, or why such a disparity exists in lakes’ longevity. To understand the controls on oxbow lakes alluviation, field observations, remotely sensed data and GIS analyses were combined. Sediment transfers in oxbow lakes were documented by topographic and sampling surveys of sites in France and Wales. Aerial photographs and maps were used to date cutoff events, analyse oxbow lakes geometry, and understand the controls on oxbow lake terrestrialisation for eight rivers of different characteristics. Findings from this study illustrate that the specific mechanism by which an oxbow lake is formed is critical to its persistence as a lake and to the sedimentary processes experienced. Chute cutoff oxbow lakes filled in 10 times faster than neck cutoffs and showed significantly different sediment deposits. Results also highlighted that oxbow lakes are not only fine-grained sediment stores, as often referred to, but can be significant bed material sinks since a site on the Ain River sequestered up to 34% of the bed material supply. However, the volume of sediment mobilised in the main channel during cutoff appeared to be larger than the bed-load stored in the former channel within the first decade after abandonment (40%). Sedimentary evidence showed that the terrestrialisation of oxbow lakes is driven by several processes: a flow separation zone at the entrance of the channel creating a sediment plug, sediment sorting by flow gradients and decantation in ponded areas. These results have important implications for the management of meandering rivers by providing a comprehensive analysis of depositional processes which also helps to predict oxbow lake longevity.

The evolutionary history of archosauromorphs is of particular interest because it includes the origins of two of the best-known and most distinctive extant tetrapod groups: crocodylians and birds. In this thesis, the anatomy, taxonomy and systematics of the Permo-Triassic non-archosaur archosauromorphs are revised. A revision of the Permo-Triassic archosauromorph record indicates that only four Permian species are known and there are three valid proterosuchid species immediately after the Permo-Triassic boundary in South Africa. Analyses of cranial ontogenetic variation in \(Proterosuchus\) \(fergusi\) found that ontogenetic modification events (e.g. heterochrony) may have been key drivers of the evolution of the general shape of the skull at the base of Archosauriformes. A comprehensive quantitative phylogenetic analysis recovered a polyphyletic “Prolacertiformes”, restricted the taxonomic content of Proterosuchidae to only six species, Erythrosuchidae was composed of eight nominal species, and \(Euparkeria\) \(capensis\) was found as the sister-taxon of the clade that includes proterochampsians (doswelliids + proterochampsids) and archosaurs. The results obtained here suggest that the evolutionary history of the archosauriforms during the Early Triassic can be subdivided into a first phase characterized by the short-lived “disaster-clade” Proterosuchidae and a second phase that witnessed the initial morphological and probably palaeoecological diversification of the group.