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In 1933, geologist and explorer Michael Terry collected the skull of a small macropodid captured by members of his party near Lake Mackay, western Northern Territory. In 1957, this skull was described as the sole exemplar of a distinct subspecies, Bettongia penicillata anhydra, but was later synonymized with B. lesueur and thereafter all but forgotten. We use a combination of craniodental morphology and ancient mitochondrial DNA to confirm that the Lake Mackay specimen is taxonomically distinct from all other species of Bettongia and recognize an additional specimen from a Western Australian Holocene fossil accumulation. B. anhydra is morphologically and genetically most similar to B. lesueur but differs in premolar shape, rostrum length, dentary proportions, and molar size gradient. In addition, it has a substantial mitochondrial cytochrome b pairwise distance of 9.6-12% relative to all other bettongs. The elevation of this recently extinct bettong to species status indicates that Australia's mammal extinction record over the past 2 centuries is even worse than currently accepted. Like other bettongs, B. anhydra probably excavated much of its food and may have performed valuable ecological services that improved soil structure and water infiltration and retention, as well as playing an important role in the dispersal of seeds and mycorrhizal fungal spores. All extant species of Bettongia have experienced extensive range contractions since European colonization and some now persist only on island refugia. The near total loss of these ecosystem engineers from the Australian landscape has far-reaching ecological implications. [ABSTRACT FROM AUTHOR]

The article describes the partial crania of two fossil species of koala bear (family Phascolarctidae) from Oligo-Miocene deposits in Australia. These fossil species are located at the Riversleigh World Heritage Area. One of the species is referable to Litokoala kutjamarpensis while the other one is referable to Nimiokoala greystanesi. It notes that a high degree of similarity in basicranial morphology between fossil and modern phascolarctids was revealed by comparing them with the extant koala Phascolarctos cinereus and other diprotodontian marsupials. Forward displacement of the palate and a decrease in the size of the pterygoid fossae are among the key specialisations present in Phascolarctos but absent in Litokoala and Nimiokoala.

Abstract: An analysis of possible developmental-functional causes of cranial form suggests that the morphology of ‘robust’ Pleistocene/Early Holocene Australians such as Willandra Lakes Human 50 might best be explained by four underlying factors: possession of a (1) large neurocranium, (2) narrow cranial base, (3) viscerocranium with considerable midfacial projection, and (4) large dentition, especially the cheek teeth, with their associated large jaws and high volume masticatory muscles. Some of these features are likely to be highly heritable, while others are caused/exaggerated by influences from ageing processes, diet, and a hunter-gatherer lifestyle in an arid environment. These underlying ‘causes’ are either apomorphies of Homo sapiens (1 and 2) and thus absent from pre-modern specimens such as from Ngandong, or represent plesiomorphic features of latter Homo (3 and 4). It is concluded that combining current knowledge of cranial development-function with genetic studies of the population history of Aboriginal Australians provides the most parsimonious solution to understanding their origins. [Copyright &y& Elsevier]

Exceptionally well-preserved remains belonging to the Australian Early Cretaceous (Albian) ichthyosaur Platypterygius longmani Wade, 1990 are described in detail. The material is used to reconstruct some of the cranial musculature and provide a brief functional analysis of the skull and mandible. Preparation of specimens using acetic acid and application of high-resolution X-ray computed tomographic analyses has revealed many previously unrecorded anatomical details, including the absence of a coronoid and squamosal, and the presence of well-developed epipterygoid facets on the pterygoid and parietal (possibly indicating retention of an unossified epipterygoid element). Reconstruction of the jaw musculature suggests a well-developed m. adductor mandibulae internus pterygoideus (serving to close the jaws against inertia and drag of the surrounding water), and possibly an m. intramandibularis (acting to accentuate static pressure along the elongate mandible when the jaws were closed). Despite its large size (maximum total body length of around 7 m), the long, narrow snout of P. longmani (together with preserved gut contents) indicates selective feeding on relatively small prey such as fish, small tetrapods and probably cephalopods. Large orbits are indicative of a visual hunter, but extensive external passages for nerves and blood vessels might suggest the presence of a dermal sensory system. The massive stapes appears to have lost all sound conductive function, serving primarily as structural support in the basicranial region. © 2005 The Linnean Society of London, Zoological Journal of the Linnean Society, 2005, 145, 583–622. [ABSTRACT FROM AUTHOR]

This study considers the craniofacial morphology of two Australian Aboriginal populations with different patterns of tooth wear. Evidence of regional variation in cranial and facial morphology is provided by significant differences in a number of variables. In addition, the intergroup differences in the correlations between attrition and facial variables provide evidence of different adaptive and compensatory changes occurring in each group in response to the different patterns of tooth wear. [ABSTRACT FROM AUTHOR]

Previous studies of genetic markers and mitochondrial DNA have found that the amount of variation among major geographic groupings of Homo sapiens is relatively low, accounting for roughly 10% of total variation. This conclusion has had implications for the study of human variation and consideration of alternative models for the origin of modern humans. By contrast, it has often been assumed that the level of among-group variation for morphological traits is much higher. This study examines the level of among-group variation based on craniometric data from a large sample of modern humans originally collected by W. W. Howells. A multivariate method based on quantitative genetics theory was used to provide an estimate of FST--a measure of among-group variation that can be compared with results from studies of genetic markers. Data for 57 craniometric variables on 1,734 crania were analyzed. These data represent six core areas: Europe, Sub-Saharan Africa, Australasia, Polynesia, the Americas, and the Far East. An additional set of analyses was performed using a three-region subset (Europe, Sub-Saharan Africa, and the Far East) to provide comparability with several genetic studies. The minimum FST (assuming complete heritability) for the three-region analysis is 0.065, and the minimum FST for the six-region analysis is 0.085. Both of these are less than the average FST from genetic studies (average estimates of 0.10-0.11). The smaller value of the minimum FST estimates is expected since it provides an estimate of FST expected under complete heritability. Using an estimate of average craniometric heritability from the literature provides an estimate of FST of 0.112 for the three-region analysis and 0.144 for the six-region analysis. These results show that genetic and craniometric data are in agreement, qualitatively and quantitatively, and that there is limited variation in modern humans among major geographic regions.

With tooth attrition, the height of the alveolar crest does not increase to keep pace with active tooth eruption and the cemento-enamel junction-alveolar crest distance increases slightly with age in aboriginal skulls. But there is no atrophy of the alveolar bony margin. Some decrease in interalveolar height does occur. This does not necessarily mean that passive eruption with exposure of cementum is normal. Rather it is postulated that the epithelial attachment proliferates onto cementum, inhibiting alveolar crest addition, while the base of the gingival sulcus remains at the cemento-enamel junction. During the course of this investigation, it was found that the distance between the cemento-enamel junction and alveolar crest increased more rapidly with advancing wear in the lower molar region than in the upper. In the lower first molar region, the lingual distance was significantly greater than that between cemento-enamel junction and alveolar crest on the buccal aspect during each stage of wear. The size of the tooth, as reflected in the robustness index, had no influence on the processes or rate of active eruption, bone deposition at the alveolar crest, or measurements taken between cemento-enamel junction and alveolar crest.