Diprotodontia
Encyclopedia
Diprotodontia is a large order
of about 120 marsupial
mammals including the kangaroo
s, wallabies
, possum
s, koala
, wombat
s, and many others. Extinct diprotodonts include the rhinoceros
-sized Diprotodon
, and Thylacoleo, the so-called "marsupial lion".
s, as were most of those that are now extinct. There are a few insectivore
and omnivore
diprotodonts, but these seem to have arisen as relatively recent adaptations from the mainstream herbivorous lifestyle. The extinct thylacoleonids
("marsupial lions") are the only known group to have exhibited carnivory
on a large scale.
Diprotodonts are restricted to Australasia
. The earliest known fossils date to the late Oligocene
. However it is certain that their genesis lies earlier than this, as there are large gaps in Australia's fossil record and virtually no fossil record at all in geologically active New Guinea
. The great diversity of known Oligocene diprotodonts suggests that the order began to diverge well beforehand.
Many of the largest and least athletic diprotodonts (along with a wide range of other Australian megafauna
) became extinct when humans first arrived in Australia about 50,000 years ago. It is possible that this extinction occurred as a direct result of hunting, but was more probably a result of widespread habitat changes brought about by human activities—notably the use of fire.
There are two key anatomical features that, in combination, identify diprotodontia. Members of the order are, first, diprotodont (meaning "two front teeth"): they have a pair of large, procumbent incisors on the lower jaw, a common feature of many early groups of mammals and mammaliforms. The diprotodont jaw is short, usually with three pairs of upper incisors (wombat
s, like rodent
s have only one pair), and no lower canines.
The second trait distinguishing diprotodonts is syndactyly, a fusing of the second and third digits of the foot up to the base of the claws which leaves the claws themselves separate. Digit five is usually absent, and digit four is often greatly enlarged.
Syndactyly is not particularly common (though the Australian omnivorous marsupials
share it) and is generally posited as an adaptation to assist in climbing. Many modern diprotodonts, however, are strictly terrestrial, and have evolved further adaptations to their feet to better suit this lifestyle. This makes the history of the tree-kangaroo
s particularly convoluted: it appears that the animals were arboreal at some time in the far distant past, moving afterward to the ground—gaining long kangaroo-like feet in the process—before returning to the trees, where they further developed a shortening and broadening of the hind feet and a novel climbing method.
of Diprotodontia dates back to the Late Oligocene (23.03mya-28.4mya), and the earliest identifiable species is Hypsiprymnodon bartholomaii from the Early Miocene
.
which encompassed the wombat
s and koala
and Phalangerida
which contained all other families. Kirsch et al. (1997) split the families into three suborders. In addition, the six Phalangeriformes families are split into two superfamilies.
Order DIPROTODONTIA
† means extinct family, genus or species.
Order (biology)
In scientific classification used in biology, the order is# a taxonomic rank used in the classification of organisms. Other well-known ranks are life, domain, kingdom, phylum, class, family, genus, and species, with order fitting in between class and family...
of about 120 marsupial
Marsupial
Marsupials are an infraclass of mammals, characterized by giving birth to relatively undeveloped young. Close to 70% of the 334 extant species occur in Australia, New Guinea, and nearby islands, with the remaining 100 found in the Americas, primarily in South America, but with thirteen in Central...
mammals including the kangaroo
Kangaroo
A kangaroo is a marsupial from the family Macropodidae . In common use the term is used to describe the largest species from this family, especially those of the genus Macropus, Red Kangaroo, Antilopine Kangaroo, Eastern Grey Kangaroo and Western Grey Kangaroo. Kangaroos are endemic to the country...
s, wallabies
Wallaby
A wallaby is any of about thirty species of macropod . It is an informal designation generally used for any macropod that is smaller than a kangaroo or wallaroo that has not been given some other name.-Overview:...
, possum
Possum
A possum is any of about 70 small to medium-sized arboreal marsupial species native to Australia, New Guinea, and Sulawesi .Possums are quadrupedal diprotodont marsupials with long tails...
s, koala
Koala
The koala is an arboreal herbivorous marsupial native to Australia, and the only extant representative of the family Phascolarctidae....
, wombat
Wombat
Wombats are Australian marsupials; they are short-legged, muscular quadrupeds, approximately in length with a short, stubby tail. They are adaptable in their habitat tolerances, and are found in forested, mountainous, and heathland areas of south-eastern Australia, including Tasmania, as well as...
s, and many others. Extinct diprotodonts include the rhinoceros
Rhinoceros
Rhinoceros , also known as rhino, is a group of five extant species of odd-toed ungulates in the family Rhinocerotidae. Two of these species are native to Africa and three to southern Asia....
-sized Diprotodon
Diprotodon
Diprotodon, meaning "two forward teeth", sometimes known as the Giant Wombat or the Rhinoceros Wombat, was the largest known marsupial that ever lived...
, and Thylacoleo, the so-called "marsupial lion".
Characteristics
Living diprotodonts are almost all herbivoreHerbivore
Herbivores are organisms that are anatomically and physiologically adapted to eat plant-based foods. Herbivory is a form of consumption in which an organism principally eats autotrophs such as plants, algae and photosynthesizing bacteria. More generally, organisms that feed on autotrophs in...
s, as were most of those that are now extinct. There are a few insectivore
Insectivore
An insectivore is a type of carnivore with a diet that consists chiefly of insects and similar small creatures. An alternate term is entomophage, which also refers to the human practice of eating insects....
and omnivore
Omnivore
Omnivores are species that eat both plants and animals as their primary food source...
diprotodonts, but these seem to have arisen as relatively recent adaptations from the mainstream herbivorous lifestyle. The extinct thylacoleonids
Thylacoleonidae
Thylacoleonidae is a family of extinct meat-eating marsupials from Australia, referred to as marsupial lions. The best known is Thylacoleo carnifex, also called the Marsupial Lion...
("marsupial lions") are the only known group to have exhibited carnivory
Carnivore
A carnivore meaning 'meat eater' is an organism that derives its energy and nutrient requirements from a diet consisting mainly or exclusively of animal tissue, whether through predation or scavenging...
on a large scale.
Diprotodonts are restricted to Australasia
Australasia
Australasia is a region of Oceania comprising Australia, New Zealand, the island of New Guinea, and neighbouring islands in the Pacific Ocean. The term was coined by Charles de Brosses in Histoire des navigations aux terres australes...
. The earliest known fossils date to the late Oligocene
Oligocene
The Oligocene is a geologic epoch of the Paleogene Period and extends from about 34 million to 23 million years before the present . As with other older geologic periods, the rock beds that define the period are well identified but the exact dates of the start and end of the period are slightly...
. However it is certain that their genesis lies earlier than this, as there are large gaps in Australia's fossil record and virtually no fossil record at all in geologically active New Guinea
New Guinea
New Guinea is the world's second largest island, after Greenland, covering a land area of 786,000 km2. Located in the southwest Pacific Ocean, it lies geographically to the east of the Malay Archipelago, with which it is sometimes included as part of a greater Indo-Australian Archipelago...
. The great diversity of known Oligocene diprotodonts suggests that the order began to diverge well beforehand.
Many of the largest and least athletic diprotodonts (along with a wide range of other Australian megafauna
Megafauna
In terrestrial zoology, megafauna are "giant", "very large" or "large" animals. The most common thresholds used are or...
) became extinct when humans first arrived in Australia about 50,000 years ago. It is possible that this extinction occurred as a direct result of hunting, but was more probably a result of widespread habitat changes brought about by human activities—notably the use of fire.
There are two key anatomical features that, in combination, identify diprotodontia. Members of the order are, first, diprotodont (meaning "two front teeth"): they have a pair of large, procumbent incisors on the lower jaw, a common feature of many early groups of mammals and mammaliforms. The diprotodont jaw is short, usually with three pairs of upper incisors (wombat
Wombat
Wombats are Australian marsupials; they are short-legged, muscular quadrupeds, approximately in length with a short, stubby tail. They are adaptable in their habitat tolerances, and are found in forested, mountainous, and heathland areas of south-eastern Australia, including Tasmania, as well as...
s, like rodent
Rodent
Rodentia is an order of mammals also known as rodents, characterised by two continuously growing incisors in the upper and lower jaws which must be kept short by gnawing....
s have only one pair), and no lower canines.
The second trait distinguishing diprotodonts is syndactyly, a fusing of the second and third digits of the foot up to the base of the claws which leaves the claws themselves separate. Digit five is usually absent, and digit four is often greatly enlarged.
Syndactyly is not particularly common (though the Australian omnivorous marsupials
Peramelemorphia
The order Peramelemorphia includes the bandicoots and bilbies: it equates approximately to the mainstream of marsupial omnivores...
share it) and is generally posited as an adaptation to assist in climbing. Many modern diprotodonts, however, are strictly terrestrial, and have evolved further adaptations to their feet to better suit this lifestyle. This makes the history of the tree-kangaroo
Tree-kangaroo
Tree-kangaroos are macropods adapted for life in trees. They are found in the rainforests of New Guinea, far northeastern Queensland, and nearby islands. Although most are found in mountainous areas, several species also occur in lowlands, such as the aptly named Lowlands Tree-kangaroo...
s particularly convoluted: it appears that the animals were arboreal at some time in the far distant past, moving afterward to the ground—gaining long kangaroo-like feet in the process—before returning to the trees, where they further developed a shortening and broadening of the hind feet and a novel climbing method.
Fossil record
The earliest known fossilFossil
Fossils are the preserved remains or traces of animals , plants, and other organisms from the remote past...
of Diprotodontia dates back to the Late Oligocene (23.03mya-28.4mya), and the earliest identifiable species is Hypsiprymnodon bartholomaii from the Early Miocene
Early Miocene
The Early Miocene is a sub-epoch of the Miocene Epoch made up of two stages: the Aquitanian and Burdigalian stages....
.
Classification
Until recently there were only two suborders in Diprotodontia: VombatiformesVombatiformes
Vombatiformes is one of the three suborders of the large marsupial order Diprotodontia. Five of the seven known families within this suborder are extinct; only the families Phascolarctidae, with the Koala, and Vombatidae, with three extant species of wombat, survive.Among the extinct families are...
which encompassed the wombat
Wombat
Wombats are Australian marsupials; they are short-legged, muscular quadrupeds, approximately in length with a short, stubby tail. They are adaptable in their habitat tolerances, and are found in forested, mountainous, and heathland areas of south-eastern Australia, including Tasmania, as well as...
s and koala
Koala
The koala is an arboreal herbivorous marsupial native to Australia, and the only extant representative of the family Phascolarctidae....
and Phalangerida
Phalangerida
Phalangerida is one of the two former suborders of the large marsupial order Diprotodontia. This large and diverse suborder included kangaroos, wallabies, quokkas, possums, gliding possum-like marsupials and others. The much smaller suborder Vombatiformes encompasses only the koalas and wombats...
which contained all other families. Kirsch et al. (1997) split the families into three suborders. In addition, the six Phalangeriformes families are split into two superfamilies.
Order DIPROTODONTIA
- Genus †BrachalletesBrachalletesBrachalletes was an early marsupial from the Pleistocene deposits of Australia. Its relationship with other marsupial species is under debate. The genus is extinct....
- Genus †Koalemas
- Genus †Sthenomerus
- Genus †NimbadonNimbadonNimbadon is an extinct genus of Diprotodontia that lived in the Miocene Epoch. Many fossils have been found in the Riversleigh World Heritage propertyin north-western Queensland.In 1990, skulls were unearthed in a previously unknown cave in the region...
- Family †ThylacoleonidaeThylacoleonidaeThylacoleonidae is a family of extinct meat-eating marsupials from Australia, referred to as marsupial lions. The best known is Thylacoleo carnifex, also called the Marsupial Lion...
(marsupial lionMarsupial lionThylacoleo is an extinct genus of carnivorous marsupials that lived in Australia from the late Pliocene to the late Pleistocene...
s) - Family †PalorchestidaePalorchestidaeThe family Palorchestidae contains four genera with eight species described. All species are extinct.*Propalorchestes **P. novaculocephalus **P. painei *Ngapakaldia...
- Family †WynyardiidaeWynyardiidaeWynyardia bassiana, an extinct possum-like marsupial from the early Miocene of Wynyard in Tasmania has long been considered to display skeletal features intermediate between the primitive polyprotodont and the advanced diprotodont marsupials. The skull examined is missing the right eye socket and...
- Suborder VombatiformesVombatiformesVombatiformes is one of the three suborders of the large marsupial order Diprotodontia. Five of the seven known families within this suborder are extinct; only the families Phascolarctidae, with the Koala, and Vombatidae, with three extant species of wombat, survive.Among the extinct families are...
- Family PhascolarctidaePhascolarctidaePhascolarctidae is a family of marsupials of the order Diprotodontia, consisting of only one extant species, the Koala, six well known fossil species, with another 5 less well known fossil species, and 2 fossil species whose taxonomy is debatable but is put in this group...
: Koala (1 species) - Family Vombatidae: wombats (3 species)
- Family †IlariidaeIlariidaeThe family Ilariidae consists of 3 species of extinct marsupial in two genera. They are all found in the middle tertiary assemblage of South Australia. Closely related to Koobor of family Phascolarctidae, which was found in Hamilton Victoria. I. illumidens is the best preserved representative of...
- Family †DiprotodontidaeDiprotodontidaeDiprotodontidae is an extinct family of large, actively mobile marsupial, endemic to what would be Australia, during the Oligocene through Pleistocene periods from 28.4 mya—11,000 years ago, existing for approximately .-References:...
- Family Phascolarctidae
- Suborder Phalangeriformes
- Superfamily Phalangeroidea
- Family PhalangeridaePhalangeridaePhalangeridae is a family of nocturnal marsupials native to Australia and New Guinea, including the cuscuses, brushtail possums, and their close relatives...
: brushtail possums and cuscuses - Family Burramyidae: pygmy possums
- Family Phalangeridae
- Superfamily PetauroideaPetauroideaPetauroidea is a superfamily of marsupials from Australia and New Guinea. It is part of the suborder Phalangeriformes within the order Diprotodontia, which also includes, among others, wombats, kangaroos, cuscuses...
- Family Tarsipedidae: Honey possum
- Family PetauridaePetauridaeThe family Petauridae includes 11 medium-sized possum species: four striped possums, the six species wrist-winged gliders in genus Petaurus, and Leadbeater's Possum which has only vestigal gliding membranes...
(Striped PossumStriped PossumThe Striped Possum is a member of the Petauridae family, one of the marsupial families. The species is black with three white stripes running head to tail, and its head has white stripes that form a 'Y' shape...
, Leadbeater's PossumLeadbeater's PossumLeadbeater's Possum is an endangered possum restricted to small pockets of remaining old growth mountain ash forests in the central highlands of Victoria north-east of Melbourne...
, Yellow-bellied GliderYellow-bellied GliderThe Yellow-bellied Glider is an arboreal and nocturnal gliding possum that lives in a narrow range of native eucalypt forests down eastern Australia, reaching from northern Queensland to Victoria.-Habitat:...
, Sugar GliderSugar GliderThe sugar glider is a small gliding possum originating from the marsupial family.The sugar glider is native to eastern and northern mainland Australia and is also native to New Guinea and the Bismarck Archipelago.- Habitat :Sugar gliders can be found all throughout the northern and eastern parts of...
, Mahogany GliderMahogany GliderThe mahogany glider is an endangered gliding possum native to a small region of coastal Queensland.-Appearance:A nocturnal arboreal marsupial, the mahogany glider closely resembles the sugar glider, the squirrel glider and the yellow-bellied glider., but is noticeably larger than any of its...
, Squirrel GliderSquirrel GliderThe Squirrel Glider is a nocturnal gliding possum, one of the wrist-winged gliders of the genus Petaurus.-Habitat:...
) - Family PseudocheiridaePseudocheiridaePseudocheiridae is a family of arboreal marsupials containing 17 extant species of ringtailed possums and close relatives. They are found in forested areas and shrublands throughout Australia and New Guinea.-Characteristics:...
: ringtailed possums and allies - Family AcrobatidaeAcrobatidaeAcrobatidae is a small family of gliding marsupials containing two genera, each with a single species, the Feathertail Glider from Australia and Feather-tailed Possum from New Guinea....
: (Feathertail GliderFeathertail GliderThe Feathertail Glider , also known as the Pygmy Gliding Possum, Pygmy Glider, Pygmy Phalanger, Flying Phalanger and Flying Mouse, is the world's smallest gliding possum and is named for its long feather-shaped tail. Although only the size of a very small mouse , it can leap and glide up to 25 metres...
and Feather-tailed PossumFeather-tailed PossumThe Feather-tailed Possum is a species of marsupial in the Acrobatidae family. It is found in West Papua, Indonesia and Papua New Guinea.It is the only species in the genus Distoechurus....
)
- Superfamily Phalangeroidea
- Suborder MacropodiformesMacropodiformesMacropodiformes is one of the three suborders of the large marsupial order Diprotodontia. Kangaroos, wallabies and allies, bettongs, potaroos and rat kangaroos are all members of this suborder.- Classification :...
- Family †BalbaridaeBalbaridaeThe Balbaridae are an extinct family of basil Macropodoidea. The synapomorphies are divided into two areas, the dental and cranial. The dental area of this taxa can be described as having the molar lophodont and brachyodont with a hypolophid formed by lingually displaced component of...
: basal quadrupedal kangaroos - Family Macropodidae: kangaroos, wallabies and allies
- Family PotoroidaePotoroidaeThe marsupial family Potoroidae includes the bettongs, potoroos, and two of the rat-kangaroos. All are rabbit-sized, brown, jumping marsupials and resemble a large rodent or a very small wallaby.- Characteristics :...
: bettongs, potaroos and rat-kangaroos - Family HypsiprymnodontidaeHypsiprymnodontidaeThe Hypsiprymnodontidae are a family of macropods, one of two families containing animals commonly referred to as rat-kangaroos. There is a single known extant genus and species in this family, the Musky Rat-kangaroo, Hypsiprymnodon moschatus, which occurs in northern Australia and New Guinea....
: Musky Rat-kangarooMusky Rat-kangarooThe Musky Rat-kangaroo is a marsupial species found in the rainforests of northeast Australia. Although some scientists place this species as a subfamily of the family Potoroidae, the most recent classification places it in the family Hypsiprymnodontidae with prehistoric rat-kangaroos.It is the... - Family ?†GangurooGangurooThe genus Ganguroo is a species of early to middle Miocene kangaroo. The relationship within the macropodidae is in dispute, though it is phylogenetically proposed to be a sister taxon with the Macropodidae.-References:...
- Family ?†Galanaria
- Family †Balbaridae
† means extinct family, genus or species.