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This thesis began as an investigation into evolution of the platypus family (Ornithorhynchidae, Monotremata), now known from both Australia and South America. The thesis broadened its scope with inclusion of non-ornithorhynchid Mesozoic monotremes from Lightning Ridge, NSW. This change in direction brought an unexpected result: a fossil mammal from Lightning Ridge investigated for this thesis (presumed to be monotreme: Flannery et al., 1995) appears to be a new and unique type of mammal. Specimens were procured through Queensland Museum (Riversleigh material); Australian Museum (Lightning Ridge material); and Museum of Victoria and the South Australian Museum (fossil ornithorhynchids). Specimens were examined under a light microscope and scanning electron microscope; specimens were photographed using light photography and a scanning electron microscope; and illustrations and reconstructions were done with a camera lucida microscope attachment and photographic references. Parsimony analysis utilised the computer programs PAUP and MacClade. Major conclusions: 1) analysis and reconstruction of the skull of the Miocene platypus Obdurodon dicksoni suggest this robust, large-billed platypus was a derived northern offshoot off the main line of ornithorhynchid evolution; 2) the well-preserved skull of Obdurodon dicksoni shows aspects of soft anatomy previously unknown for fossil ornithorhynchids; 3) two upper molars from Mammalon Hill (Etadunna Formation, late Oligocene, central Australia) represent a third species of Obdurodon; 4) the South American ornithorhynchid Monotrematum sudamericanum from the Paleocene of Argentina is very close in form to the Oligocene-Miocene Obdurodon species from Australia and should be considered congeneric; 5) a revised diagnosis of the lower jaw of the Early Cretaceous monotreme Steropodon galmani includes the presence of two previously undescribed archaic features: the probable presence of postdentary bones and a meckelian groove; 6) morphological evidence is presented supporting a separate family Steropodontidae; and 7) analysis of new fossil material for Kollikodon ritchiei suggests that this taxon is not a monotreme mammal as originally identified but is a basal mammal with close relationships to allotherian mammals (Morganucodonta; Haramiyida). Kollikodon is provisionally placed as basal allotherian mammal (Allotheria sensu Butler 2000) and is unique at the ordinal level, being neither haramiyid nor multituberculate. A new allotherian order ??? Kollikodonta ??? is proposed.

Inferences regarding the biology of extinct taxa are often founded primarily on cladistically-based phylogenetic hypotheses. However, these inferences are frequently inconsistent with the morphology and physiology of modern animals. I suggest that reference to the biology of modern animals might be a more appropriate tool to aid in the reconstruction of the morphology and physiology of extinct animals. Here, this methodology is applied to: (1) reconstruction of the respiratory anatomy and physiology of some Paleozoic archosaurs (dinosaurs, early birds, pterosaurs, and early crocodilians), (2) understanding cursorial locomotion in birds and bipedal dinosaurs, and (3) a reinterpretation of an enigmatic archosaur, Longisquama. The conclusions drawn from these data raise questions regarding current thinking regarding relationships between birds and dinosaurs. / Graduation date: 2000

This thesis began as an investigation into evolution of the platypus family (Ornithorhynchidae, Monotremata), now known from both Australia and South America. The thesis broadened its scope with inclusion of non-ornithorhynchid Mesozoic monotremes from Lightning Ridge, NSW. This change in direction brought an unexpected result: a fossil mammal from Lightning Ridge investigated for this thesis (presumed to be monotreme: Flannery et al., 1995) appears to be a new and unique type of mammal. Specimens were procured through Queensland Museum (Riversleigh material); Australian Museum (Lightning Ridge material); and Museum of Victoria and the South Australian Museum (fossil ornithorhynchids). Specimens were examined under a light microscope and scanning electron microscope; specimens were photographed using light photography and a scanning electron microscope; and illustrations and reconstructions were done with a camera lucida microscope attachment and photographic references. Parsimony analysis utilised the computer programs PAUP and MacClade. Major conclusions: 1) analysis and reconstruction of the skull of the Miocene platypus Obdurodon dicksoni suggest this robust, large-billed platypus was a derived northern offshoot off the main line of ornithorhynchid evolution; 2) the well-preserved skull of Obdurodon dicksoni shows aspects of soft anatomy previously unknown for fossil ornithorhynchids; 3) two upper molars from Mammalon Hill (Etadunna Formation, late Oligocene, central Australia) represent a third species of Obdurodon; 4) the South American ornithorhynchid Monotrematum sudamericanum from the Paleocene of Argentina is very close in form to the Oligocene-Miocene Obdurodon species from Australia and should be considered congeneric; 5) a revised diagnosis of the lower jaw of the Early Cretaceous monotreme Steropodon galmani includes the presence of two previously undescribed archaic features: the probable presence of postdentary bones and a meckelian groove; 6) morphological evidence is presented supporting a separate family Steropodontidae; and 7) analysis of new fossil material for Kollikodon ritchiei suggests that this taxon is not a monotreme mammal as originally identified but is a basal mammal with close relationships to allotherian mammals (Morganucodonta; Haramiyida). Kollikodon is provisionally placed as basal allotherian mammal (Allotheria sensu Butler 2000) and is unique at the ordinal level, being neither haramiyid nor multituberculate. A new allotherian order ??? Kollikodonta ??? is proposed.

A well preserved, fossiliferous Middle Triassic to Early Cretaceous section lies on the west side of Harrison Lake in the southern Coast Mountains. The study of this area involves a re-evaluation of the stratigraphic nomenclature first described by Crickmay (1925, 1930a) together with a lithologic description of the units and age determinations based on collected, identified and described fossils by the writer. Discussions on the biostratigraphy, paleogeography, regional correlations and structure of the thesis area and an overview of the regional tectonics of southwestern British Columbia and northwestern Washington, help to better understand the relation of this Mesozoic section to other rock assemblages in this geologically complex region. The oldest unit, the Middle Triassic Camp Cove Formation, comprises conglomeratic sandstone, siltstone and minor volcanic rock. Unconformable7 overlying this unit is the Toarcian to Early(?) Bajocian Harrison Lake Formation, divided into four distinct members by the writer, Celia Cove Member (basal conglomerate), West Road Member (siltstone, shale), Weaver Lake Member (flows, pyroclastic rocks, minor sediments) and Echo Island Member (interbedded tuff, siltstone, sandstone). Thickness of this formation is estimated at 3000 m. A hiatus probably is present between this unit and overlying shale, siltstone and sandstone of the Early Callovian Mysterious Creek Formation which is 700 m thick. Conformably above this are 230 m of sandstone and volcaniclastic rock of the Early Oxfordian Billhook Creek Formation. Late Jurassic fluvial conglomerate, sandstone and siltstone of the Kent Formation, perhaps 1000 m thick south of Harrison River, unconformably(?) overlies the last two units mentioned. Berriasian to Valanginian conglomerate and sandstone, 218 m thick, of the Peninsula Formation overlies the Billhook Creek Formation with slight angular unconformity. The Peninsula Formation is conformably overlain by tuffaceous sandstone, volcanic conglomerate, crystal tuff and flows of the Valanginian to Middle Albian Brokenback Hill Formation which is several km thick. Nine Jurassic ammonite genera are identified and described in this report. Triassic radiolaria and conpdonts and Cretaceous ammonites and bivalves are also present in the section. The most significant structure in the thesis area is the post-Albian to pre-Late Eocene Harrison Fault which strikes north-northwest through Harrison Lake, separating the Mesozoic section along the west side from the northern extension of the Cascade Metamorphic Core on the east side of the lake. A strong sub-horizontal stretching lineation within the fault zone may indicate right-lateral strike-slip movement. / Science, Faculty of / Earth, Ocean and Atmospheric Sciences, Department of / Graduate