Browsing by Author "Hand, Suzanne."
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Item First crania and assessment of species boundaries in Nimbadon (Marsupialia, Diprotodontidae) from the middle Miocene of Australia. (American Museum novitates, no. 3678)(New York, NY : American Museum of Natural History., 2010) Black, Karen H.; Hand, Suzanne.Abundant, exceptionally well-preserved cranial material of the zygomaturine diprotodontid Nimbadon lavarackorum is described from AL90 site, a middle Miocene deposit in the Riversleigh World Heritage Area, Queensland, Australia. The material has enabled a comprehensive assessment of the expected level of morphological variation within a fossil marsupial species from a single locality, thus forming a benchmark for determining species boundaries in extinct marsupials. Variation is assessed by quantitative and qualitative means. Univariate analyses of N. lavarackorum cranial and dental dimensions indicate low coefficients of variation consistent with expected values for single species populations. Conversely, qualitative analyses indicate high levels of morphological variation, particularly in structures previously deemed phylogenetically significant, such as the upper third premolar. Some cranial variation may be due to sexual dimorphism or ontogeny but there appears to be a high degree of intraspecific morphological variation. Features once regarded to distinguish N. whitelawi from the type species fall within the boundaries of that intraspecific variation and N. whitelawi is herein regarded as a junior synonym of N. lavarackorum. Comparison with morphological variation in the Miocene diprotodontid Neohelos stirtoni suggests that N. lavarackorum was a less variable species overall, reflecting differences between the taxa in body size, home range, and habitat preference and stability. Nimbadon lavarackorum was a relatively small (75-120 kg), possibly gregarious browsing species probably restricted to closed-forest habitats.Item New genus and species of extinct Miocene ringtail possums (Marsupialia, Pseudocheiridae) ; American Museum novitates, no. 3560(New York, NY : American Museum of Natural History, 2007) Roberts, Karen K.; Archer, Michael, 1945-; Hand, Suzanne.; Godthelp, Henk.The first unique genus of ringtail possums from the Riversleigh World Heritage Area in Australia is diagnosed and described. Gawinga aranaea is the type and only species of the new genus and is known from nine isolated lower molars. It has been recovered from three Riversleigh deposits: two are of early to mid-Miocene age, while the age of the other has yet to be determined. The new possum is larger than Oligo-Miocene species of Paljara, Pildra, and Marlu, but smaller than most extant taxa. It is characterised by a distinctive lower molar cusp morphology of parallel ridges extending primarily from the cristid obliqua, filling the occlusal basins. Additional autapomorphies include: extended, shelflike protostylid cristids and a bisected posthypocristid on m1, and posterior molars that have a metaconid ridge posterobuccal to the metaconid and an anteriorly positioned protoconid relative to the metaconid. It also possesses an enlarged protostylid on m1, a feature otherwise known only in extant genera. The precise phylogenetic position of Gawinga within the pseudocheirid radiation has yet to be determined, but it is tentatively identified here to be a highly derived pseudocheirid, apomorphic with respect to Paljara and Pildra species, and with no known descendants.