Marsupial moles are highly specialized marsupial mammals, known from two species found at the Australian interior.
- Notoryctes typhlops (southern marsupial mole, known as the itjaritjari by the Pitjantjatjara and Yankunytjatjara people in Central Australia).
- Notoryctes caurinus (northern marsupial mole, also known as the kakarratul)
|Southern marsupial mole|
|Ranges of marsupial mole species|
Notoryctids are small, fossorial mammals that anatomically converge on other fossorial (and distantly related) mammals, such as living golden moles (Chrysochloridae) and extinct epoicotheres (Pholidota).
Like chrysochlorids and epoicotheres, notoryctids use their forelimbs and enlarged central claws to dig in a parasagittal (i.e., up and down) plane, as opposed to the "lateral scratch" style of digging that characterizes talpid moles.
Marsupial moles spend most of their time underground, coming to the surface only occasionally, probably mostly after rains. They are blind, their eyes having become reduced to vestigial lenses under the skin which lack a pupil. Therefore they are functionally blind. They have no external ears, just a pair of tiny holes hidden under thick hair. The head is cone-shaped, with a leathery shield over the muzzle, the body is tubular, and the tail is a short, bald stub encased in leathery skin. They are between 12 and 16 centimetres (4.7–6.3 in) long, weigh 40 to 60 grams (1.4–2.1 oz), and are uniformly covered in fairly short, very fine pale cream to white hair with an iridescent golden sheen. Their pouch is small but well developed and has evolved to face backwards so it does not fill with sand. It contains just two teats, so the animal cannot bear more than two young at a time.
The limbs are very short, with reduced digits. The forefeet have two greatly enlarged, spade shaped, flat claws on the third and fourth digits, which are used to excavate soil in front of the animal. The hindfeet are flattened, and bear three small claws; these feet are used to push soil behind the animal as it digs. Epipubic bones are present but small and as in some other fossorial mammals (e.g., armadillos), the last five cervical vertebrae are fused to give the head greater rigidity during digging. The animal swims through the soil and doesn't leave behind any permanent burrow.
The teeth of the marsupial moles are degenerate and bear no resemblance to polyprotodont or diprotodont teeth. Their dental formula varies, but is usually somewhere near 4–220.127.116.11 × 2 = 42–44. The upper molars are zalambodont, and the lower molars appear to have lost their talonid basins. The molar teeth of Notoryctes are triangular, or "zalambdodont", i.e., resembling an inverted Greek letter "lambda" in occlusal view.
Notoryctids are represented by early Miocene fossils of Naraboryctes from site of Riversleigh in Queensland, Australia, which document the mosaic acquisition of dental and skeletal features of the living Notoryctes from a more terrestrial ancestor. The notoryctid fossil record demonstrates that the primary cusp of the molars is the metacone, distinct from the paracone characteristic of zalambdodont tenrecs, golden moles, and Solenodon. Regarding the number of teeth in each dental quadrant (or dental formula) Archer et al. (2011) reported that "the dental formula for species of Notoryctes is controversial because of considerable polymorphism in tooth number, both between specimens and within the same specimen." Nonetheless, reflecting the consensus of older studies, Archer et al. (2011) report the presence of four molars (typical for marsupials) in each quadrant both in living Notoryctes and the fossil notoryctid Naraboryctes.
American paleontologist William King Gregory wrote in 1910 (p. 209) that "Notoryctes is a true marsupial" and this view has been repeatedly verified by phylogenetic analyses of comparative anatomy, mitochondrial DNA, nuclear DNA, rare genomic events, and combined datasets of nuclear and mitochondrial DNA and morphology and DNA. The largest phylogenetic datasets strongly support the placement of Notoryctes as the sister taxon to a dasyuromorph-peramelian clade, within the Australidelphian radiation.
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- University of Western Australia marsupial mole home page
- Research mission to discover conservation requirements (includes photo)
- Nature news story (includes photo)
- AusEmade: Marsupial Mole Information
- Archer, Hand & Godthelp, Australia's lost world: Riversleigh, World Heritage Site, Reed New Holland, 1991. ISBN 1-876334-59-2
- ARKive - images and movies of the marsupial mole (Notoryctes typhlops)
- Australian Geographic - The marsupial mole: an enduring enigma