• Assessing the Potential for Radiocarbon Dating the Scales of Australian Lungfish (Neoceratodus forsteri)

      James, Kelly M.; Fallon, Stewart J.; McDougall, Andrew; Espinoza, Tom; Broadfoot, Craig (Department of Geosciences, The University of Arizona, 2010-01-01)
      We present a novel application for radiocarbon dating by aging 4 scales from a single large adult lungfish (Neoceratodus forsteri) from the Burnett River, in Queensland, Australia. The relict fish species lack a solid crystalline otolith, which precludes the use of the otolith annuli as a reliable age indicator. Previous attempts to age lungfish using a number of techniques have had only limited success. We report on ages obtained from the dense lamellar bone of the scale, which were isolated from the organic layers that thicken and subsequently obscure the 14C signal. Using the characteristics of the bomb curve, 2 parameter von Bertanalffy growth functions were fit, providing an estimate of absolute age to be ~65-70 yr. The information gleaned from this study will aid in assessing the population structure, and therefore management, of this vulnerable species.
    • Pre-Bomb Marine Reservoir Variability in the Kimberley Region, Western Australia

      O'Connor, Sue; Ulm, Sean; Fallon, Stewart J.; Barham, Anthony; Loch, Ian (Department of Geosciences, The University of Arizona, 2010-01-01)
      New Delta-R values are presented for 10 known-age shells from the Kimberley region of northwest Australia. Previous estimates of Delta-R for the Kimberley region are based on only 6 individual shell specimens with dates of live collection known only to within 50 yr (Bowman 1985a). Here, we describe the results of our recent attempts to constrain Delta-R variability for this region by dating a suite of known-age pre-AD 1950 shell samples from the Australian Museum and Museum Victoria. A regional Delta-R of 58 +/- 17 14C yr for open waters between Broome and Cape Leveque is recommended based on 7 of these specimens. The criteria used to select shells for dating and inclusion in the regional mean are discussed.