D. Rex Mitchell

Verified

D. verified their affiliation via an institutional email.

Learn more

Verified

D. verified their affiliation via an institutional email.

Learn more

• PhD
• PostDoc Position at Flinders University

The Sthenurinae were a diverse subfamily of short-faced kangaroos that arose in the Miocene and diversified during the Pliocene and Pleistocene. Many species possessed skull morphologies that were relatively structurally reinforced with bone, suggesting that they were adapted to incorporate particularly resistant foods into their diets. However, th...

Comparative finite element analysis involves standardising aspects of models to test equivalent loading scenarios across species. However, regarding feeding biomechanics of the vertebrate skull, what is considered “equivalent” can depend on the hypothesis. Using 13 diversely-shaped skulls of marsupial bettongs and potoroos (Potoroidae), we demonstr...

The mammalian cranium (skull without lower jaw) is representative of mammalian diversity and is thus of particular interest to mammalian biologists across disciplines. One widely retrieved pattern accompanying mammalian cranial diversification is referred to as ‘craniofacial evolutionary allometry’ (CREA). This posits that adults of larger species,...

Objectives Orangutans are found in tropical rainforests of Borneo ( Pongo pygmaeus ) and Sumatra ( Pongo abelii and Pongo tapanuliensis ), and they are primarily considered frugivorous species. However, ecological studies reported differences in feeding behavior between these species. P. pygmaeus spend more time feeding on low‐quality foods, such a...

Pathologies of the skull and teeth are well documented for many human populations, but there are fewer studies of other primates. We contrast lesion prevalence and patterning among cercopithecoid primates and map variation onto socioecological variables. We compare craniodental lesions in six species: Nasalis larvatus ( n = 54), Colobus polykomos (...

The shared functions of the skull are thought to result in common evolutionary patterns in mammalian cranial shape. Craniofacial evolutionary allometry (CREA) is a particularly prominent pattern where larger species display proportionally elongate facial skeletons and smaller braincases. It was recently proposed that CREA arises from biomechanical...

Potoroid marsupials (bettongs and potoroos of the family Potoroidae) are considered ecosystem engineers because of the roles they play in maintaining biodiversity. However, severe declines since European arrival have necessitated intense conservation efforts. Vital to these efforts is an understanding of the physical challenges that define their ni...

In assessments of skeletal variation, allometry (disproportionate change of shape with size) is often corrected to examine size-independent variation for hypotheses relating to function. However, size-related trade-offs in functional demands may themselves be an underestimated driver of mammalian cranial diversity. Here, we use geometric morphometr...

Decommissioning the dingo barrier fence has been suggested to reduce destructive dingo control and encourage a free transfer of biota between environments in Australia. Yet the potential impacts that over a century of predator exclusion might have had on the population dynamics and developmental biology of prey populations has not been assessed. We...

There is controversy around the mechanisms that guided the change in brain shape during the evolution of modern humans. It has long been held that different cortical areas evolved independently from each other to develop their unique functional specializations. However, some recent studies suggest that high integration between different cortical ar...

The temporomandibular joint is the direct interface between the mandible and the cranium and is critical for transmitting joint reaction forces and determining mandibular range of motion. As a consequence, understanding variation in the morphology of this joint and how it relates to other aspects of craniofacial form is important for better underst...

The extinct Haast's eagle or harpagornis ( Hieraaetus moorei ) is the largest known eagle. Historically, it was first considered a predator, then a scavenger, but most recent authors have favoured an active hunting ecology. However, the veracity of proposed similarities to carrion feeders has not been thoroughly tested. To infer feeding capability...

The rescue and rehabilitation of young fauna is of substantial importance to conservation. However, it has been suggested that incongruous diets offered in captive environments may alter craniofacial morphology and hinder the success of reintroduced animals. Despite these claims, to what extent dietary variation throughout ontogeny impacts intrapop...

Objectives Craniofacial fluctuating asymmetry (FA) refers to the random deviations from symmetry exhibited across the craniofacial complex and can be used as a measure of developmental instability for organisms with bilateral symmetry. This article addresses the lack of data on craniofacial FA in nonhuman primates by analyzing FA magnitude and vari...

We found that when researchers preferentially seek to only landmark specimens in good condition, they may be ignoring entire demographic-specific shape data from groups of individuals more likely to exhibit damage and/or pathology.

Obtaining coordinate data for geometric morphometric studies often involves the sampling of dry skeletal specimens from museum collections. But many specimens exhibit damage and/or pathologic conditions. Such specimens can be considered inadequate for the analyses of shape and are excluded from study. However, the influences that damaged specimens...

The sparse record of Cretaceous crocodyliforms in Australia comprises only three species, all within the genus Isisfordia. Isisfordia duncani Salisbury et al., 2006 is from the Albian-Turonian Winton Formation of Queensland, and both Isisfordia molnari Hart et al., 2019 and Isisfordia selaslophensis Etheridge, 1917 have been described from opalized...

Large brains are a defining feature of primates, as is a clear allometric trend between body mass and brain size. However, important questions on the macroevolution of brain shape in primates remain unanswered. Here we address two: (i), does the relationship between the brain size and its shape follow allometric trends and (ii), is this relationshi...

Interspecific variation in the craniofacial morphology of kangaroos and wallabies is associated with diet and feeding behaviors. Yet, to how fine a taxonomic scale this relationship might exist is unknown. Using a combination of established morphometric analyses and novel finite element approaches, we test the limits of these associations by examin...

Large herbivores can act as keystone species that strongly influence their communities. During the Pliocene and Pleistocene, Australia was dominated by a number of large to gigantic marsupial herbivore taxa. Many of these have been understudied quantitatively with regard to their ecology; and identifying the diet of these species will improve our u...

Increasing body size is accompanied by facial elongation across a number of mammalian taxa. This trend forms the basis of a proposed evolutionary rule, cranial evolutionary allometry (CREA). However, facial length has also been widely associated with the varying mechanical resistance of foods. Here, we combine geometric morphometrics and computatio...

Octopus kapalae, sp. nov. is described from preserved specimens housed in the Australian Museum, Sydney. The species is found on the edge of the continental shelf off south-eastern Australia, at depths between 176 m and 503 m. The possession of large eggs suggests the young hatch as miniature adults and do not disperse widely. The species may be en...

The Swamp Wallaby (Wallabia bicolor), maintains a broad distribution along the eastern coast of Australia and records have indicated that its range may be expanding. Reported here is the first record of the species from the Barossa Valley region, South Australia. The specimen was deceased when collected and vouchered in the South Australian Museum....

The highly invasive freshwater snail, Physa acuta, was examined for parasites over temporal and spatial scales. All populations studied had a high prevalence of the parasitic morph of the oligochaete worm, Chaetogaster limnaei. This worm was also found to infect two native snails, Glyptophysa gibbosa and Austropeplea tomentosa, at lower prevalences...