Marsupial moles Temporal range: 20–0 Ma Miocene to Recent |
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Scientific classification | |
Kingdom: | Animalia |
Phylum: | Chordata |
Class: | Mammalia |
Infraclass: | Marsupialia |
Superorder: | Australidelphia |
Order: |
Notoryctemorphia Kirsch, in Hunsaker, 1977 |
Family: |
Notoryctidae Ogilby, 1892 |
Genus: |
Notoryctes Stirling, 1891 |
Species | |
Ranges of marsupial mole species |
Marsupial moles are a family (Notoryctidae) of cladotherian mammals of the order Notoryctemorphia. They are rare and poorly understood burrowing mammals of the deserts of Western Australia, with an ancestry going back 20 million years or so. Once classified as monotremes, they are now thought to be marsupials. Their precise classification was for long a matter for argument, but there are considered to be only two extant species:
The two species are so similar to one another that they cannot be reliably told apart in the field.
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, and they have no external ears, just a pair of tiny holes hidden under thick hair. It is debated whether or not marsupial moles dig permanent burrows or simply fill their tunnels in behind them as they move.
The head is cone-shaped, with a leathery shield over the muzzle, the body is tubular, and the tail is a short, bald stub. They are between 12 and 16 cm long, weigh 40 to 60 grams, and are uniformly covered in fairly short, very fine pale cream to white hair with an iridescent golden sheen. Their pouch has evolved to face backwards so it does not fill with sand, and 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 large, 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. In a feature unique to this animal, the neck vertebrae are fused to give the head greater rigidity during digging.