Thesis (Ph.D.) - James Cook University, 2004. / Typescript (photocopy) Bibliography: leaves 293-326.

Thesis (Ph.D.) -- University of Glasgow, 2002. / Ph.D. thesis submitted to the Division of Environmental and Evolutionary Biology, Institute of Biomedical and Life Sciences, University of Glasgow, 2002. Includes bibliographical references (p. 161-195). Print version also available. Mode of access : World Wide Web. System requirements : Adobe Acrobat reader required to view PDF document.

Thesis (Ph. D.)--University of Victoria, 1998. / Includes bibliographical references (leaves 243-269).

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Dissertation submitted to the Faculty of Science, University of the Witswatersrand, Johannesburg, in fulfilment of the requirements for the degree of Master of Science. May 2015 in Johannesburg / Claudins are a large gene family found in all vertebrates. Claudins encode tetraspan membrane proteins, involved in the structure and function of the tight junctions. This association of cells leads to the formation of the epithelial sheet which is involved in many functions such as embryo morphogenesis. The NCBI database shows 27 claudins identified in humans; 23 in mice and 17 in Xenopus. This suggests that an increase in gene family size may correlate with the evolution of more complex vertebrates. In this study claudins from the most basal extant vertebrate, the sea lamprey, were investigated. RNA used to build up the lamprey genome by Jeramiah Smith (Smith et al., 2012), was used for lamprey claudin sequences. Additionally this study identified 2 more claudins (Cldn B & Cldn F). The phylogenetic tree constructed using claudins from higher vertebrate model organisms and the invertebrates Ciona intestinalis and Drosophila melanogaster; showed that lamprey claudins are evolutionarily more distantly related to their orthologs in higher vertebrates. Furthermore some claudins in lamprey did not show any homologs in higher vertebrates and vice versa, indicating the emergence of novel members in higher vertebrates. However lamprey Cldn A was found to be homologous to CLDN 3 in higher vertebrates. This is interesting since CLDN 3 is involved in the development of two vertebrate specific traits; one of which is the ear placode. Thus Cldn A (renamed Cldn 3B), was made a focus of this study. RNA in situ hybridization using probes designed from individual UTRs showed localised expression of Cldn 3B in the ear placode, pharyngeal pouch, pericardial cavity and the fin fold whereas Cldn B (renamed Cldn 8B) was mostly expressed in the pharyngeal pouch and ear placode much like its orthologs in higher vertebrates. Knockout experiments showed that Cldn 3B is involved in sealing and expansion of the ear placode and pharyngeal arches during development whereas Cldn 8B is involved in determining ear placode development. Thus claudins are seen to be heavily involved in the morphology of vertebrate specific traits therefore an expansion in this gene family would affect the complexity of vertebrates during evolution.

Thesis (Ph. D.)--University of Chicago, Dept. of Organismal Biology and Anatomy, August 1999. / Includes bibliographical references. Also available on the Internet.

Thesis (M.Sc.). / Written for the Dept. of Biology. Title from title page of PDF (viewed 2008/12/05). Includes bibliographical references.

With the transition from water to land in early tetrapods, and with transitions to secondarily aquatic habits in numerous tetrapod lineages, the functions of the vertebral column were transformed. Morphological changes in the vertebral column are a major mechanism by which vertebrates accommodate changes in locomotor forces. Although morphometric measurements from vertebrae have been correlated with axial mechanics and locomotor behaviour in numerous extant taxa, few studies have sought to test or apply these principles in non-mammalian tetrapods. In my thesis, I reconstructed the vertebral mechanics of fossil taxa that represent intermediate stages in water/land transitions of their lineages. Study taxa were the basal tetrapod Pederpes finneyae, which is one of the earliest known tetrapods to show indications of terrestrial adaptation, and three extinct crocodylomorphs, Terrestrisuchus, Protosuchus, and Pelagosaurus, which span the spectrum from fully terrestrial to primarily aquatic. I used a combination of morphometric measurements and 3D virtual models of bone morphology to estimate intervertebral joint stiffness and range of motion. For comparison, I also reconstructed the vertebral mechanics of four related extant taxa. Correlations between vertebral morphometrics and axial stiffness were statistically tested in (cadaveric) modem crocodylians, and I validated my methodology by comparing my results with data from extant taxa. My results reveal similarities and differences between the two lineages. Intervertebral joint compliance and range of motion tended to decrease with adaptation for terrestrial locomotion, as expected, but this trend seems to have reversed in later forms. Additionally, vertebral mechanics may have been largely controlled by different structural mechanisms in different lineages. The relationship between biomechanics of vertebrae and environment appears to be more complex than previously supposed. However, approaches that combine experimental measurements from extant animals, thorough analysis of fossil morphology, and explicit phylogenetic considerations have the potential to greatly improve locomotor reconstructions of extinct taxa.

Jawed vertebrates (gnathostomes) account for over 99% of living vertebrate diversity, with origins that stretch back nearly half a billion years, and comprise two groups: Osteichthyes (fishes and land-dwelling vertebrates) and Chondrichthyes (sharks, rays and chimaeras). Osteichthyans are the dominant clade, with at least 60,000 species approximately evenly divided between two clades: the Actinopterygii and the Sarcopterygii. However, our understanding of early osteichthyan evolution is skewed in favour of sarcopterygians, leaving the origin of nearly half of all vertebrate diversity critically understudied. Furthermore, recent upheavals in the early gnathostome tree have destabilised relationships amongst fossil taxa and eroded our understanding of primitive anatomical conditions of key groups. Central to understanding early gnathostome evolution is the braincase, an anatomically complex structure that provides a wealth of morphological characters. However, braincases rarely fossilise, and their position inside the skull makes them difficult to attain. X-ray tomography allows a comprehensive description of the internal and external anatomy of fossils, including the braincase. This thesis sets out to target phylogenetically pivotal taxa and incorporate new anatomical data in building up a picture of character evolution in early jawed vertebrates. In particular, I target the gnathostome stem, describing a new taxon that helps bridge the morphological gap between placoderms and crown gnathostomes, allowing a more comprehensive understanding of both dermal and endoskeletal evolution. I also focus on early actinopterygians, describing the endoskeleton of the first members of the group in order to understand primitive anatomical conditions. I then investigate actinopterygian braincase anatomy in the context of a revised phylogenetic analysis, illuminating the early evolution of the actinopterygians. Finally, I present a synthetic review of braincase anatomy across the early gnathostome tree. These results provide a more accurate picture of braincase evolution across gnathostomes and actinopterygians, clarifying our understanding of their evolution while revealing new information about when key innovations arose in the brains of the very first ray-finned fishes.