Natalie M. Warburton

An arid-adapted middle Pleistocene vertebrate fauna from south-central Australia

How well the ecology, zoogeography and evolution of modern biotas is understood depends substantially on knowledge of the Pleistocene. Australia has one of the most distinctive, but least understood, Pleistocene faunas. Records from the western half of the continent are especially rare. Here we report on a diverse and exceptionally well preserved middle Pleistocene vertebrate assemblage from caves beneath the arid, treeless Nullarbor plain of south-central Australia. Many taxa are represented by whole skeletons, which together serve as a template for identifying fragmentary, hitherto indeterminate, remains collected previously from Pleistocene sites across southern Australia. A remarkable eight of the 23 Nullarbor kangaroos are new, including two tree-kangaroos. The diverse herbivore assemblage implies substantially greater floristic diversity than that of the modern shrub steppe, but all other faunal and stable-isotope data indicate that the climate was very similar to today. Because the 21 Nullarbor species that did not survive the Pleistocene were well adapted to dry conditions, climate change (specifically, increased aridity) is unlikely to have been significant in their extinction.

Enhancing self-directed learning through a content quiz group learning assignment:

This article presents the findings of an empirical study that examined the learning value of a novel group assessment activity aimed at promoting first-year students’ development of basic self-directed learning skills required for university study. A content quiz group learning assignment was designed to enhance students’ capacity to ask appropriate questions to guide their enquiry, identify appropriate resources and tools, and draw links between different learning resources, all skills embedded within their learning in a science unit. Questionnaire data and written reflections revealed the extent to which students used core, accessory and optional resources to complete this assignment, which specific resources were perceived as most useful for what aspects of their content learning, and how strategy use was related to achievement. Metacognitive experiences expressed in the open questions and assessed reflections revealed students’ emerging awareness of how their approach to study impacted on the quality of their learning.

Adaptations for digging in the forelimb muscle anatomy of the southern brown bandicoot (Isoodon obesulus) and bilby (Macrotis lagotis)

Abstract. Bandicoots and bilbies (Peramelemorphia) represent a distinct lineage within the marsupial adaptive radiation, which despite several curious anatomical traits has received little morphological attention. Many bandicoot species (family Peramelidae) dig for subterranean food, while bilbies (family Thylacomyidae) employ their forelimbs to dig extensive burrow systems for shelter. In the current study, dissections of the southern brown bandicoot (Isoodon obesulus) (n = 7) and greater bilby (Macrotis lagotis) (n = 4) provide the first anatomical descriptions of forelimb musculature in these species. The anatomical arrangement of forelimb muscles in I. obesulus and M. lagotis differs from that of other marsupials and corresponds to the aclaviculate pectoral girdle and modified arrangement of digits in the study species. Comparative and functional interpretations indicate that the forelimb of I. obesulus is well equipped for scratch digging and demonstrates muscular modifications in order to generate large out-forces. The bones of the forelimb, and in particular the antebrachium, are relatively short, stout bones, improving both their resistance to mechanical forces and providing a mechanical advantage via a reduced out-lever length. There has been an increase in the absolute volume of muscles employed during digging, thereby increasing the magnitude of the in-force. Increased in-lever lengths have been achieved via the migration of muscle insertions, including the elongate olecranon for the insertion of the m. triceps brachii, and the distal migration of the humeral attachments of the teres major, latissimus dorsi and superficial pectoral muscles.

A new Pleistocene tree-kangaroo (Diprotodontia: Macropodidae) from the Nullarbor Plain of south-central Australia

Abstract This paper describes a new tree-kangaroo of the extinct genus Bohra (B. illuminata sp. nov.). Its remains were collected from a diverse middle Pleistocene fauna preserved in caves recently discovered beneath the Nullarbor Plain of south-central Australia. The adult holotype and juvenile paratype are represented by associated cranial and postcranial material. They confirm that two previously known species, B. paulae and B. wilkinsonorum, which were described on the basis of disparate parts of the skeleton, are congeneric. While Bohra is closest in morphology to the extant tree-kangaroo genus Dendrolagus, it shares several similarities with Petrogale (rock-wallabies). This is consistent with recent molecular studies that suggest that tree-kangaroos and rock-wallabies share a common ancestry.

Comparative Jaw Muscle Anatomy in Kangaroos, Wallabies, and Rat‐Kangaroos (Marsupialia: Macropodoidea)

The jaw muscles were studied in seven genera of macropodoid marsupials with diets ranging from mainly fungi in Potorous to grass in Macropus. Relative size, attachments, and lamination within the jaw adductor muscles varied between macropodoid species. Among macropodine species, the jaw adductor muscle proportions vary with feeding type. The relative mass of the masseter is roughly consistent, but grazers and mixed‐feeders (Macropus and Lagostrophus) had relatively larger medial pterygoids and smaller temporalis muscles than the browsers (Dendrolagus, Dorcopsulus, and Setonix). Grazing macropods show similar jaw muscle proportions to “ungulate‐grinding” type placental mammals. The internal architecture of the jaw muscles also varies between grazing and browsing macropods, most significantly, the anatomy of the medial pterygoid muscle. Potoroines have distinctly different jaw muscle proportions to macropodines. The masseter muscle group, in particular, the superficial masseter is enlarged, while the temporalis group is relatively reduced. Lagostrophus fasciatus is anatomically distinct from other macropods with respect to its masticatory muscle anatomy, including enlarged superficial medial pterygoid and deep temporalis muscles, an anteriorly inflected masseteric process, and the shape of the mandibular condyle. The enlarged triangular pterygoid process of the sphenoid bone, in particular, is distinctive of Lagsotrophus. Anat Rec, 292:875–884, 2009.

Forelimb musculature of kangaroos with particular emphasis on the tammar wallaby Macropus eugenii (Desmarest, 1817)

Comparative morphological studies can provide insights into an animal’s ecology and evolutionary history. Functional morphological studies of the kangaroo forelimb are few in number and new work could provide novel tools to aid in the interpretation of fossil taxa and the understanding of the evolutionary history of kangaroos and marsupials as a whole. A description of the shoulder and forelimb musculature of the tammar wallaby (Macropus eugenii) with comparisons to the red kangaroo (Macropus rufus Desmarest, 1842), the western grey kangaroo (Macropus fuliginosus Desmarest, 1817) and the quokka (Setonix brachyurus Quoy & Gaimard, 1830) is presented. The species chosen were readily available and represent a range in size of the archetypal kangaroo form. Muscle maps of forelimb and shoulder muscles were constructed as an aid to comparing the spatial arrangement of muscle origins and insertions. The anatomical pattern of forelimb musculature in terrestrial macropodine kangaroos and wallabies is highly conservative. Functionally, the musculature of the forelimb corresponds to a supporting role of the limb during slow pentapedal locomotion. The illustrations of muscle insertions provided in this work will be a useful reference for future work in comparative marsupial anatomy and palaeobiology.

Functional Morphology of the Forelimb of Living and Extinct Tree-Kangaroos (Marsupialia: Macropodidae)

Tree‐kangaroos are a unique group of arboreal marsupials that evolved from terrestrial ancestors. The recent discovery of well‐preserved specimens of extinct tree‐kangaroo species (genus Bohra) within Pleistocene cave deposits of south‐central Australia provides a unique opportunity to examine adaptive evolution of tree‐kangaroos. Here, we provide the first detailed description of the functional anatomy of the forelimb, a central component of the locomotor complex, in the extant Dendrolagus lumholtzi, and compare its structure and function with representatives of other extant marsupial families. Several features were interpreted as adaptations for coping with a discontinuous, uneven and three‐dimensional arboreal substrate through enhanced muscular strength and dexterity for propulsion, grasping, and gripping with the forelimbs. The forelimb musculoskeletal anatomy of Dendrolagus differed from terrestrial kangaroos in the following principal ways: a stronger emphasis on the development of muscles groups responsible for adduction, grasping, and gripping; the enlargement of muscles that retract the humerus; and modified shape of the scapula and bony articulations of the forelimb bones to allow improved mobility. Many of these attributes are convergent with other arboreal marsupials. Tree‐kangaroos, however, still retain the characteristic bauplan of their terrestrial ancestors, particularly with regard to skeletal morphology, and the muscular anatomy of the forelimb highlights a basic conservatism within the group. In many instances, the skeletal remains of Bohra have similar features to Dendrolagus that suggest adaptations to an arboreal habit. Despite the irony of their retrieval from deposits of the Nullarbor “Treeless” Plain, forelimb morphology clearly shows that the species of Bohra were well adapted to an arboreal habitat. J. Morphol. 2011.

Anatomical adaptations of the hind limb musculature of tree- kangaroos for arboreal locomotion (Marsupialia:Macropodinae)

Abstract. Tree-kangaroos (Dendrolagini) are Australasian marsupials that inhabit tropical forests of far north-eastern Queensland and New Guinea. The secondary adaptation of tree-kangaroos to an arboreal lifestyle from a terrestrial heritage offers an excellent opportunity to study the adaptation of the musculoskeletal system for arboreal locomotion, particularly from a template well adapted to terrestrial bipedal saltation. We present a detailed descriptive study of the hind limb musculature of Lumholtz’s tree-kangaroo (D. lumholtzi) in comparison to other macropodines to test whether the hind limb musculature of tree-kangaroos is functionally adapted to the different mechanical demands of locomotion in the uneven three-dimensional arboreal environment. The hind limb musculature of Lumholtz’s tree-kangaroo (Dendrolagus lumholtzi), the western brush wallaby (Macropus irma), the western grey kangaroo (Macropus fuliginosus) and the quokka (Setonix brachyurus) are described. The hind limb anatomy of D. lumholtzi differed from that of the terrestrial macropodines in that the muscles had a greater degree of internal differentiation, relatively longer fleshy bellies and very short, stout tendons of insertion. There was also a modified arrangement of muscle origins and insertions that enhance mechanical advantage. Differences in the relative proportions of the hind limb muscle mass between tree-kangaroos and terrestrial macropodines reflect adaptation of the limb musculature of tree-kangaroos for arboreal locomotion. The hind limb musculature of Setonix was different to that of both Dendrolagus and Macropus, possibly reflecting its more basal phylogenetic position within the Macropodinae.

The biology and palaeontology of the Peramelemorphia: a review of current knowledge and future research directions

Abstract. Bandicoots and bilbies (Marsupialia : Peramelemorphia) represent the dominant omnivorous clade of Australasian marsupials and, as ground-dwelling, small- to medium-sized mammals, have not fared well in the 200 years since European settlement. Unlike large or charismatic marsupial species, the cryptic nature of bandicoots and bilbies tends to keep them out of the public eye, at a time when public interest plays a significant role in conservation efforts. The inconspicuous ‘rat-like’ appearance of many bandicoots and a generalist ecological strategy belie a complex biology of adaptive traits and evolutionary diversity. For a few species these biological traits have enabled them to make use of urban environments. In the main, however, peramelemorphians are facing ongoing pressure from introduced predators and human impacts. Basic biological information for many species, particularly those from New Guinea, is still lacking. In this review, we examine advances in the knowledge of the biology of this group over the past 25 years including anatomical, physiological and ecological studies. We also provide a comprehensive review of the fossil records of bandicoots in order to provide an up-to-date platform for future studies. From this work, it is clear that there is still much to be done regarding the taxonomy and biology of these animals before a more detailed understanding of the evolutionary history of this group can be elucidated.

Walking on five legs: investigating tail use during slow gait in kangaroos and wallabies

Abstract. Pentapedal locomotion is the use of the tail as a fifth leg during the slow gait of kangaroos. Although previous studies have informally noted that some smaller species of macropodines do not engage in pentapedal locomotion, a systematic comparative analysis of tail use during slow gait across a wide range of species in this group has not been done. Analysis of relative movement of the pelvis, tail, and joint angles of the lower limbs during slow gait, using 2D landmark techniques on video recordings, was carried out on 16 species of Macropodinae. We also compared the relative lengthening of the tibia using crural index (CI) to test whether hindlimb morphology was associated with pentapedal locomotion. Pentapedal locomotion was characterised by three features: the presence of the ‘tail repositioning phase’, the constant height of the pelvis and the stationary placement of the distal tail on the ground during the hindlimb swing phase. The mean CI of pentapedal species was significantly greater than that of non-pentapedal species (1.71 versus 1.36; P < 0.001). This lends support to the hypothesis that the use of pentapedal locomotion is associated with the relative lengthening of the hindlimb, which in turn is associated with body size and habitat preference within the Macropodinae.