Academic literature on the topic 'Notoryctes'

MARSUPIAL moles (Notoryctes spp.) remain one of the great enigmas of the Australian fauna. Their occurrence is highly sporadic, resulting in a slow trickle of specimens to Museums at the rate of around 5-15 per decade (Johnson 1995). Their small size, cryptic habits, remote distribution and wariness have led to few reported sightings. In addition, the difficulty of keeping captive Notoryctes has restricted the collection of basic biological information (Howe 1975; Corbett 1975; Johnson and Walton 1989).

The phylogenetic position of the marsupial mole, Notorcytes typhlops, has been difficult to ascertain with morphological characters because of its highly specialised fossorial lifestyle. On the basis of serological data, Kirsch (1977b) suggested that this species was sufficiently different from other marsupials to warrant placing it in its own suborder. Using the DNA-DNA hybridisation technique on single-copy DNA to assess sequence differences over the entire genome, I confirm that N. typhlops is not closely related to any other marsupial family, and warrants placement in its own order.

We studied the thermal and metabolic physiology of a single specimen of the north-western marsupial mole, Notoryctes caurinus, an almost completely fossorial Australian marsupial, and compared it with the morphologically convergent Namib desert golden mole, Eremitalpa granti namibensis. This was the first study of any aspect of the physiology of this rare marsupial. Mean body mass of the marsupial mole was 34 g. Body temperature (Tb) was low and labile, ranging from 22.7 to 30.8˚C over a range of ambient temperature (Ta) from 15 to 30˚C. The highest Tb of 30.8˚C was significantly lower than expected for a marsupial of this body mass. Metabolic rate varied with Ta in an attenuated fashion for an endotherm, because of the labile Tb. Basal metabolic rate (BMR) was 0.63 mL O2 g–1 h–1, at a Ta of 30˚C. This was lower than expected for a 34-g marsupial, but was not different from expected for a marsupial when corrected to a Tb of 35˚C (0.94 mL O2 g–1 h–1). Evaporative water loss increased from 0.8 mg g–1 h–1 at 15˚C to 3.7 at 30˚C. Wet thermal conductance was 0.2 mL O2 g–1 h–1 ˚C–1 at 15˚C and 0.6 at 25˚C; these values were higher than expected for a marsupial. The net metabolic cost of transport (NCOT) for running (0.0022 mL O2 g–1 m–1 at a mean velocity of 484 m h–1) was similar to expected values for walking and running mammals. The NCOT for sand-swimming (0.124 mL O2 g–1 m–1 at a mean velocity of 7.6 m h–1) was substantially higher, and at a much lower velocity than for running, but was similar to NCOT for sand-swimming by the Namib golden mole. We conclude that the marsupial mole differs in some aspects of thermal and metabolic physiology from other marsupials, most likely reflecting its almost completely fossorial existence.

Little ecological information has been collected on the Marsupial Mole, Notoryctes typhlops, since its discovery in 1888. The only field data published on the species this century has resulted from opportunistic encounters with the animal (Johnson and Walton 1989), and no reliable methods for capturing it or monitoring its abundance and distribution have been developed. In 1920 a second species of Marsupial Mole, Notorcytes caurinus, was described from specimens collected in north-western Australia. The distributions of the two species have not been clearly differentiated however, and the two species are often regarded as synonymous (e.g. Johnson 1995). In this paper the potential for a second species was disregarded and reference is made only to N. typhlops due to the proximity of the study sites to the location of recent records of this species.

Little is known about the distribution and ecology of the cryptic and unique marsupial mole. In this paper we report on the habitat preferences and surfacing behaviour of marsupial moles on the basis of surface sign surveys conducted in Uluru-Kata Tjuta National Park and Ayers Rock Resort over a 12-month period by Uluru-Kata Tjuta National Park staff and traditional owners. A key aim of the study was to assess the potential viability of using surface sign as a rapid, non-intrusive alternative to traditional survey methods. We found that surfacing occurred widely across the study area, but that it was highly variable both across survey sites and over time. Significant relationships existed between surface sign counts and environmental variables, including fire age, timing of significant rainfall events, presence of infrastructure and the cumulative rainfall received in the preceding three months. We concluded that the use of marsupial mole surface sign is likely to be a useful method for monitoring the distribution, abundance and habitat requirements of this cryptic species.

The musculoskeletal system of marsupial mammals has numerous unusual features beyond the pouch and epipubic bones. One example is the widespread absence or reduction (to a fibrous “patelloid”) of the patella (“kneecap”) sesamoid bone, but prior studies with coarse sampling indicated complex patterns of evolution of this absence or reduction. Here, we conducted an in-depth investigation into the form of the patella of extant marsupial species and used the assembled dataset to reconstruct the likely pattern of evolution of the marsupial patella. Critical assessment of the available literature was followed by examination and imaging of museum specimens, as well as CT scanning and histological examination of dissected wet specimens. Our results, from sampling about 19% of extant marsupial species-level diversity, include new images and descriptions of the fibrocartilaginous patelloid in Thylacinus cynocephalus (the thylacine or “marsupial wolf”) and other marsupials as well as the ossified patella in Notoryctes ‘marsupial moles’, Caenolestes shrew opossums, bandicoots and bilbies. We found novel evidence of an ossified patella in one specimen of Macropus rufogriseus (Bennett’s wallaby), with hints of similar variation in other species. It remains uncertain whether such ossifications are ontogenetic variation, unusual individual variation, pathological or otherwise, but future studies must continue to be conscious of variation in metatherian patellar sesamoid morphology. Our evolutionary reconstructions using our assembled data vary, too, depending on the reconstruction algorithm used. A maximum likelihood algorithm favours ancestral fibrocartilaginous “patelloid” for crown clade Marsupialia and independent origins of ossified patellae in extinct sparassodonts, peramelids, notoryctids and caenolestids. A maximum parsimony algorithm favours ancestral ossified patella for the clade [Marsupialia + sparassodonts] and subsequent reductions into fibrocartilage in didelphids, dasyuromorphs and diprotodonts; but this result changed to agree more with the maximum likelihood results if the character state reconstructions were ordered. Thus, there is substantial homoplasy in marsupial patellae regardless of the evolutionary algorithm adopted. We contend that the most plausible inference, however, is that metatherians independently ossified their patellae at least three times in their evolution. Furthermore, the variability of the patellar state we observed, even within single species (e.g. M. rufogriseus), is fascinating and warrants further investigation, especially as it hints at developmental plasticity that might have been harnessed in marsupial evolution to drive the complex patterns inferred here.

In most areas of Australia, mammals constitute the staple diets of cats, foxes and dingoes. In central Australia the abundance of mammals is often too low to meet the dietary requirements of these carnivores and yet populations of cats, foxes and dingoes persist. To investigate alternative feeding strategies of cats, foxes and dingoes in arid environments, their diets were monitored in relation to prey availability in two areas of the Tanami Desert where rabbits do not occur. Dietary information was obtained by analysing predator scats collected between 1995 and 1997. Prey availability was monitored by track counts, pitfall trapping, Elliott trapping, and bird counts along walked transects. In contrast to dietary studies elsewhere in Australia, it was found that reptiles were an important component of the diets of predators in the Tanami Desert, and should be classified as seasonal staples. Birds increased in importance in the diets of cats and foxes during the winter, when reptiles were less active. There was considerable overlap between the diets of all three predators, although dingoes ate more large prey items (e.g.�macropods) than the other two predators. Results highlight the opportunistic feeding habits of cats, foxes and dingoes and show that, although mammalian prey are less important in central Australia than has been found elsewhere, species that are vulnerable to extinction, such as the bilby (Macrotis lagotis), mulgara (Dasycercus cristicauda) and marsupial mole (Notoryctes typhlops), are also consumed by these predators.

Marsupial moles (genus Notoryctes) are the most highly specialised burrowing marsupials. The specialisations of the appendicular musculo-skeletal system of the marsupial moles are extensive and widespread; the major alterations are concentrated in, but not restricted to, the forelimb. Many of the derived features of the muscular system appear to be adaptations for improving the mechanical advantage of the limbs for burrowing. A number of the specialisations of the muscular system of the marsupial moles are convergent with those previously documented in other fossorial mammals, including golden moles, rodents and armadillos. There are, however, a number of unique specialisations of the musculo-skeletal system of Notoryctes. The functional morphology of the locomotor apparatus of marsupial moles is interpreted on the basis of the descriptions of the anatomy of the skeletal and muscular systems. The burrowing technique of the marsupial moles is a modified form of the parasagittal digging method that is used by other fossorial mammals, such as golden moles, armadillos and some rodents including pocket gophers. Differences in the functional morphology of the hindlimb between marsupial moles and other fossorial mammals are a reflection of the fact that marsupial moles do not construct permanent open burrow systems, but instead constantly dig through loose soil, backfilling as they progress. The functional morphology of the tail is uniquely specialised in the marsupial moles to function as the fifth limb during the pentapedal burrowing locomotion of marsupial moles. The remains of Miocene fossil marsupial mole, while clearly pleisiomorphic with respect to the appendicular skeletal morphology of modern notoryctids, demonstrate a high degree of specialisation for digging. It is hypothesised that the Miocene marsupial mole was already substantially specialised for a fossorial lifestyle, and thus pre-adapted for a subterranean lifestyle developed in correlation with the desertification of the Australian continent. Phylogenetic affinities of marsupial moles within the Marsupialia have long been enigmatic. While specialisation of the musculo-skeletal system have been so widespread as to obscure almost any phylogenetically relevant patterns, there is some evidence to support an association between notoryctids and peramelid bandicoots. Interspecific differences between the two species of marsupial moles, Notoryctes typhlops and N. caurinus, are minor but do support the separation of the two species.