Obudrodon Dicksoni
INVESTIGATIONS INTO THE EVOLUTION OF AUSTRALIAN MAMMALS WITH A FOCUS ON MONOTREMATA
Thesis submitted by
ANNE MARIE MUSSER
August 2005
For the Degree of Doctor of Philosophy in the School of Biological, Earth & Environmental Sciences University of New South Wales
ABSTRACT
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
Thesis submitted by
ANNE MARIE MUSSER
August 2005
For the Degree of Doctor of Philosophy in the School of Biological, Earth & Environmental Sciences University of New South Wales
ABSTRACT
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
References: 7 BONAPARTE, J.F., 1987 8 DUN, W.S., 1895 10 MIAO, D., 1991 13 WOODBURNE, M.O., RICH, T.A., AND SPRINGER, M.S., 2003