![]() Surprisingly, we found that on the day of birth, despite crawling to the pouch and attaching to the mother's teat, the joeys had formed no mineralised bone tissue (ossification) anywhere in their body. We used this technique to see when the bones and soft tissues first arise. The young were examined using micro-computed tomography (microCT), a non-invasive imaging tool that provides 3-dimensional (3D) images of the internal structures with very high resolution. ![]() Our research team raised a colony of dunnarts and collected joeys from birth to weaning. Joeys need to have highly developed forelimbs to crawl to the pouch and a well-developed mouth and nose to attach to the teat, suckle and breathe simultaneously. We were most interested in these structures because marsupials have this extreme shift in the timing of when the forelimbs and oral region appear compared to placental mammals such as mice and humans. Our latest research focussed on the development of the bones of the skull and forelimbs. In laboratory mice, development of the organs, bones and brain largely occurs during pregnancy. When the joeys are born, they are smaller than a grain of rice, with the heart, lungs, and bladder visible through their translucent skin. Credit: University of Melbourneįat-tailed dunnarts have one of the shortest pregnancies of any mammal-only 13.5 days. (b) The secondary jaw joint close up abbreviations of bones: c = condyle (orange), et = ectotympanic ring (purple), gf = glenoid fossa (light green), in = incus (yellow), ml = malleus (blue) and sq = squamosal (dark green). (a) View of the secondary jaw joint with inset white box showing entire skull. Pictures show the secondary jaw joints in microCT scans in fat-tailed dunnart pouch young. It is also a Dasuyrid marsupial, belonging to the same order as the endangered Tasmanian devil, the numbat and the extinct thylacine (Tasmanian tiger).įat-tailed dunnarts need well-developed mouth and nose to attach to the teat, suckle and breathe simultaneously. ![]() More recently the fat-tailed dunnart is emerging as an important model species for expanding our understanding of the evolution of the mammalian brain, retina development in nocturnal species and as a tool for marsupial conservation.Īlthough the fat-tailed dunnart isn't itself endangered, other dunnart species including the Kangaroo Island dunnart and Sandhill dunnart are. They can live in areas ranging from open woodland to arid shrublands, undergoing daily hibernation or torpor, lowering their body temperature and metabolic rate to reduce energy expenditure in response to environmental conditions. Its long carrot-shaped tail (almost the same length as its body) stores fat reserves for when food is scarce It's one of the smallest carnivorous marsupials, coming out at night to eat insects, spiders, amphibians and even small mammals and reptiles. It has a head and body length of between 60-90mm, tail 45-70cm in length and weighs only 10-20g. The fat-tailed dunnart belongs to the Dasyuridae family, which also includes Tasmanian devils and quolls. One species, the fat-tailed dunnart (Sminthopsis crassicaudata) was first described in the literature in 1844 by English ornithologist John Gould and since the mid-1900s has been of great interest to scientists due to its ability to survive in extreme, semi-arid environments. However, this is where their closeness ends, since they last shared a common ancestor approximately 160 million years ago. They're so similar to mice in fact, that in cold temperatures, dunnarts have been known to keep warm by sharing their nests with the common house mouse. It's unlikely however, that you've caught a fleeting glimpse of one of the 19 species of Australia's most elusive marsupials scurrying through the grass at night.ĭunnarts are nocturnal marsupials-mammals who carry young in a pouch-that are often referred to as " marsupial mice".
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