Marsupial moles, the Notoryctidae , are highly specialized marsupial mammals, known from two species found at the Australian interior.
* ''
Notoryctes typhlops
The southern marsupial mole (''Notoryctes typhlops''), also known as the itjaritjari () or itjari-itjari, is a mole-like marsupial found in the western central deserts of Australia. It is extremely adapted to a burrowing way of life. It has larg ...
'' (southern marsupial mole, known as the ''itjaritjari'' by the
Pitjantjatjara
The Pitjantjatjara (; or ) are an Aboriginal people of the Central Australian desert near Uluru. They are closely related to the Yankunytjatjara and Ngaanyatjarra and their languages are, to a large extent, mutually intelligible (all are vari ...
and
Yankunytjatjara
The Yankunytjatjara people, also written Yankuntjatjarra, Jangkundjara, and other variants, are an Aboriginal Australian people of the state of South Australia.
Language
Yankunytjatjara is a Western Desert language belonging to the Wati la ...
people in Central Australia).
* ''
Notoryctes caurinus
The northern marsupial mole or kakarratul (''Notoryctes caurinus'') is a marsupial in the family Notoryctidae, an endemic animal of arid regions of Central Australia. It lives in the loose sand of dunes and river plains in the desert, spending ne ...
'' (northern marsupial mole, also known as the ''kakarratul'')
Notoryctids are small,
fossorial
A fossorial () animal is one adapted to digging which lives primarily, but not solely, underground. Some examples are badgers, naked mole-rats, clams, meerkats, and mole salamanders, as well as many beetles, wasps, and bees.
Prehistoric eviden ...
mammals that anatomically converge on other fossorial (and distantly related) mammals, such as living golden moles (
Chrysochloridae
Golden moles are small insectivorous burrowing mammals endemic to Sub-Saharan Africa. They comprise the family Chrysochloridae and as such they are taxonomically distinct from the true moles, family Talpidae, and other mole-like families, all o ...
) and extinct
epoicotheres (
Pholidota
Pangolins, sometimes known as scaly anteaters, are mammals of the order Pholidota (, from Ancient Greek ϕολιδωτός – "clad in scales"). The one extant family, the Manidae, has three genera: ''Manis'', ''Phataginus'', and ''Smutsia'' ...
).
Characteristics
In an example of
convergent evolution
Convergent evolution is the independent evolution of similar features in species of different periods or epochs in time. Convergent evolution creates analogous structures that have similar form or function but were not present in the last com ...
, notoryctids resemble (and fill the
ecological niche
In ecology, a niche is the match of a species to a specific environmental condition.
Three variants of ecological niche are described by
It describes how an organism or population responds to the distribution of resources and competitors (for ...
of)
moles Moles can refer to:
* Moles de Xert, a mountain range in the Baix Maestrat comarca, Valencian Community, Spain
* The Moles (Australian band)
*The Moles, alter ego of Scottish band Simon Dupree and the Big Sound
People
*Abraham Moles, French engin ...
from North America and Eurasia and
golden mole
Golden moles are small insectivorous burrowing mammals endemic to Sub-Saharan Africa. They comprise the family Chrysochloridae and as such they are taxonomically distinct from the true moles, family Talpidae, and other mole-like families, all o ...
s from Southern Africa. 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
Underground most commonly refers to:
* Subterranea (geography), the regions beneath the surface of the Earth
Underground may also refer to:
Places
* The Underground (Boston), a music club in the Allston neighborhood of Boston
* The Underground ...
, coming to the surface only occasionally, probably mostly after rains. They are functionally
blind, their eyes having become reduced to
vestigial
Vestigiality is the retention, during the process of evolution, of genetically determined structures or attributes that have lost some or all of the ancestral function in a given species. Assessment of the vestigiality must generally rely on co ...
lenses under the skin which lack a pupil. 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 long, weigh , 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
teat
A teat is the projection from the mammary glands of mammals from which milk flows or is ejected for the purpose of feeding young. In many mammals the teat projects from the udder. The number of teats varies by mammalian species and often corre ...
s, so the animal cannot support 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
Epipubic bones are a pair of bones projecting forward from the pelvic bones of modern marsupials, monotremes and fossil mammals like multituberculates, and even basal eutherians (the ancestors of placental mammals, who lack them).
They first oc ...
are present but small and as in some other fossorial mammals (e.g.,
armadillo
Armadillos (meaning "little armored ones" in Spanish) are New World placental mammals in the order Cingulata. The Chlamyphoridae and Dasypodidae are the only surviving families in the order, which is part of the superorder Xenarthra, along wi ...
s), the last five cervical
vertebra
The spinal column, a defining synapomorphy shared by nearly all vertebrates,Hagfish are believed to have secondarily lost their spinal column is a moderately flexible series of vertebrae (singular vertebra), each constituting a characteristic ...
e 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 . The upper molar teeth are triangular and
zalambdodont
The molars or molar teeth are large, flat teeth at the back of the mouth. They are more developed in mammals. They are used primarily to grind food during chewing. The name ''molar'' derives from Latin, ''molaris dens'', meaning "millstone ...
, i.e., resembling an inverted Greek letter
lambda
Lambda (}, ''lám(b)da'') is the 11th letter of the Greek alphabet, representing the voiced alveolar lateral approximant . In the system of Greek numerals, lambda has a value of 30. Lambda is derived from the Phoenician Lamed . Lambda gave rise ...
in occlusal view, and the lower molars appear to have lost their talonid basins.
Fossil record
Notoryctids are represented by early
Miocene
The Miocene ( ) is the first geological epoch of the Neogene Period and extends from about (Ma). The Miocene was named by Scottish geologist Charles Lyell; the name comes from the Greek words (', "less") and (', "new") and means "less recen ...
fossils of ''
Naraboryctes
''Naraboryctes philcreaseri'' is a fossil species of marsupial found at early Miocene deposits of Boodjamulla National Park of Riversleigh area, northwestern Queensland, Australia.
Taxonomy
It was first named by Michael Archer, Robin Beck, M ...
'' from
Riversleigh in Queensland, Australia, which document the
mosaic
A mosaic is a pattern or image made of small regular or irregular pieces of colored stone, glass or ceramic, held in place by plaster/mortar, and covering a surface. Mosaics are often used as floor and wall decoration, and were particularly pop ...
acquisition of dental and skeletal features of the living ''Notoryctes'' from a more surface-dwelling 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
Dentition pertains to the development of teeth and their arrangement in the mouth. In particular, it is the characteristic arrangement, kind, and number of teeth in a given species at a given age. That is, the number, type, and morpho-physiolo ...
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''.
Evolutionary affinities
American paleontologist
William King Gregory
William King Gregory (May 19, 1876 – December 29, 1970) was an American zoologist, renowned as a primatologist, paleontologist, and functional and comparative anatomist. He was an expert on mammalian dentition, and a leading contributor t ...
br>
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
Mitochondrial DNA (mtDNA or mDNA) is the DNA located in mitochondria, cellular organelles within eukaryotic cells that convert chemical energy from food into a form that cells can use, such as adenosine triphosphate (ATP). Mitochondrial D ...
, 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
Dasyuromorphia (, meaning "hairy tail" in Greek) is an order comprising most of the Australian carnivorous marsupials, including quolls, dunnarts, the numbat, the Tasmanian devil, and the thylacine. In Australia, the exceptions include the o ...
-
peramelian clade, within the
Australidelphian radiation.
[Mitchell KJ, Pratt RC, Watson LN, Gibb GC, Llamas B, Kasper M, Edson J, Hopwood B, Male D, Armstrong KN, Meyer M. Molecular phylogeny, biogeography, and habitat preference evolution of marsupials. Molecular biology and evolution. 2014 Sep 1;31(9):2322-30.]
References
University of Western Australia marsupial mole home page(includes photo)
(includes photo)
* Archer, Hand & Godthelp, ''Australia's lost world: Riversleigh, World Heritage Site'', Reed New Holland, 1991.
External links
*ARKive
images and movies of the marsupial mole ''(Notoryctes typhlops)''*Australian Geographic
Mole
Notoryctidae
Mammals of Western Australia
Extant Burdigalian first appearances