Diprotodontia (, from

Greek Greek may refer to: Anything of, from, or related to Greece, a country in Southern Europe: *Greeks, an ethnic group *Greek language, a branch of the Indo-European language family **Proto-Greek language, the assumed last common ancestor of all kno ...

"two forward teeth") is the largest extant order of marsupials, with about 155 species, including the

kangaroo Kangaroos are marsupials from the family Macropodidae (macropods, meaning "large foot"). In common use, the term is used to describe the largest species from this family, the red kangaroo, as well as the antilopine kangaroo, eastern gre ...

s, wallabies,

possums Possum may refer to: Animals * Didelphimorphia, or (o)possums, an order of marsupials native to the Americas ** Didelphis, a genus of marsupials within Didelphimorphia *** Common opossum, native to Central and South America *** Virginia opossum, ...

koala The koala (''Phascolarctos cinereus''), sometimes inaccurately called the koala bear, is an arboreal herbivorous marsupial native to Australia. It is the only Extant taxon, extant representative of the Family (biology), family ''Phascolar ...

wombat Wombats are short-legged, muscular quadrupedal marsupials of the family Vombatidae that are native to Australia. Living species are about in length with small, stubby tails and weigh between . They are adaptable and habitat tolerant, and are ...

s, and many others. Extinct diprotodonts include the

hippopotamus The hippopotamus (''Hippopotamus amphibius;'' ; : hippopotamuses), often shortened to hippo (: hippos), further qualified as the common hippopotamus, Nile hippopotamus and river hippopotamus, is a large semiaquatic mammal native to sub-Sahar ...

-sized '' Diprotodon'', and '' Thylacoleo'', the so-called "marsupial lion".

Characteristics

Living diprotodonts are almost all

herbivore A herbivore is an animal anatomically and physiologically evolved to feed on plants, especially upon vascular tissues such as foliage, fruits or seeds, as the main component of its diet. These more broadly also encompass animals that eat ...

s, as were most of those that are now

extinct Extinction is the termination of an organism by the death of its Endling, last member. A taxon may become Functional extinction, functionally extinct before the death of its last member if it loses the capacity to Reproduction, reproduce and ...

. A few

insectivorous A robber fly eating a hoverfly An insectivore is a carnivorous animal or plant which eats insects. An alternative term is entomophage, which can also refer to the human practice of eating insects. The first vertebrate insectivores we ...

and

omnivorous An omnivore () is an animal that regularly consumes significant quantities of both plant and animal matter. Obtaining energy and nutrients from plant and animal matter, omnivores digest carbohydrates, protein, fat, and fiber, and metabolize ...

diprotodonts are known, and the Potoroidae are almost unique among vertebrates in being largely

fungivorous Fungivory or mycophagy is the process of organisms consuming fungi. Many different organisms have been recorded to gain their energy from consuming fungi, including birds, mammals, insects, plants, amoebas, gastropods, nematodes, bacteria and othe ...

, 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 A carnivore , or meat-eater (Latin, ''caro'', genitive ''carnis'', meaning meat or "flesh" and ''vorare'' meaning "to devour"), is an animal or plant whose nutrition and energy requirements are met by consumption of animal tissues (mainly mu ...

on a large scale. Diprotodonts are restricted to

Australasia Australasia is a subregion of Oceania, comprising Australia, New Zealand (overlapping with Polynesia), and sometimes including New Guinea and surrounding islands (overlapping with Melanesia). The term is used in a number of different context ...

. The earliest known fossils date to the late

Oligocene The Oligocene ( ) is a geologic epoch (geology), epoch of the Paleogene Geologic time scale, Period that extends from about 33.9 million to 23 million years before the present ( to ). As with other older geologic periods, the rock beds that defin ...

, but their genesis certainly lies earlier than this, as large gaps occur in Australia's fossil record, with virtually no fossil record at all in geologically active

New Guinea New Guinea (; Hiri Motu: ''Niu Gini''; , fossilized , also known as Papua or historically ) is the List of islands by area, world's second-largest island, with an area of . Located in Melanesia in the southwestern Pacific Ocean, the island is ...

. The great diversity of known Oligocene diprotodonts suggests the order began to diverge well beforehand. Many of the largest and least athletic diprotodonts (along with a wide range of other

Australian megafauna The term Australian megafauna refers to the megafauna in Australia (continent), Australia during the Pleistocene, Pleistocene Epoch. Most of these species became extinct during the latter half of the Pleistocene, as part of the broader global L ...

) became extinct when humans first arrived in Australia about 50,000 years ago. Their extinction possibly 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. Two key anatomical features, 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 (

s, like

rodent Rodents (from Latin , 'to gnaw') are mammals of the Order (biology), order Rodentia ( ), which are characterized by a single pair of continuously growing incisors in each of the upper and Mandible, lower jaws. About 40% of all mammal specie ...

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-kangaroos 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

fossil A fossil (from Classical Latin , ) is any preserved remains, impression, or trace of any once-living thing from a past geological age. Examples include bones, shells, exoskeletons, stone imprints of animals or microbes, objects preserve ...

of Diprotodontia dates back to the

Late Oligocene The Chattian is, in the geologic timescale The geologic time scale or geological time scale (GTS) is a representation of time based on the rock record of Earth. It is a system of chronological dating that uses chronostratigraphy (the pro ...

(23.03 - 28.4 million years ago), and the earliest identifiable species is '' Hypsiprymnodon bartholomaii'' from the

Early Miocene The Early Miocene (also known as Lower Miocene) is a sub-epoch of the Miocene epoch (geology), Epoch made up of two faunal stage, stages: the Aquitanian age, Aquitanian and Burdigalian stages. The sub-epoch lasted from 23.03 ± 0.05 annum, Ma to ...

.The Paleobiology Database
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Classification

Until recently, only two

suborder Order () is one of the eight major hierarchical taxonomic ranks in Linnaean taxonomy. It is classified between family and class. In biological classification, the order is a taxonomic rank used in the classification of organisms and recognized ...

s in Diprotodontia were noted: Vombatiformes which encompassed the

s and

and Phalangerida which contained all other families. Kirsch et al. (1997) split the families into three

s. In addition, the six

Phalangeriformes Phalangeriformes is a paraphyletic suborder of about 70 species of small to medium-sized arboreal locomotion, arboreal marsupials native to Australia, New Guinea, and Sulawesi. The species are commonly known as possums, opossums, gliders, and ...

families are split into two superfamilies. The Macropodiformes are probably nested within the Phalangeriformes, though whether they are sister to Phalangeroidea or Petauroidea is debated. Order Diprotodontia * Suborder

Macropodiformes The Macropodiformes , also known as macropods, are one of the three suborders of the large marsupial order Diprotodontia. They may in fact be nested within one of the suborders, Phalangeriformes. Kangaroos, wallabies and allies, bettongs, p ...

** Family Hypsiprymnodontidae: ( musky rat-kangaroo) ** Family

Macropodidae Macropodidae is a Family (biology), family of marsupials that includes kangaroos, Wallaby, wallabies, tree-kangaroos, wallaroos, pademelons, quokkas, and several other groups. These genera are allied to the suborder Macropodiformes, containing ...

: ( kangaroos, wallabies and allies) ** Family Potoroidae: ( bettongs, potoroos, and rat-kangaroos) ** Family † Balbaridae: (basal quadrupedal kangaroos) * Suborder

** Superfamily Petauroidea *** Family

Acrobatidae The Acrobatidae are a small family of flying and gliding animals, gliding marsupials containing two genera, each with a single species, the feathertail glider (''Acrobates pygmaeus'') from Australia and feather-tailed possum (''Distoechurus penna ...

: (

feathertail glider The feathertail glider (''Acrobates pygmaeus''), also known as the pygmy gliding possum, pygmy glider, pygmy phalanger, flying phalanger and flying mouse, is a species of marsupial native to eastern Australia. It is the world's smallest gliding ...

and

feather-tailed possum The feather-tailed possum (''Distoechurus pennatus'') is a species of marsupial in the family Acrobatidae. It is found in West Papua and Papua New Guinea. It is not to be confused with the feathertail glider, the only other species in the family ...

) *** Family Petauridae: ( striped possum,

Leadbeater's possum Leadbeater's possum (''Gymnobelideus leadbeateri'') is a critically endangered Phalangeriformes, possum largely restricted to small pockets of Eucalyptus delegatensis, alpine ash, Eucalyptus regnans, mountain ash, and Eucalyptus pauciflora, sno ...

, yellow-bellied glider, sugar glider,

mahogany glider The mahogany glider (''Petaurus gracilis'') is an endangered gliding possumsquirrel glider) *** Family Pseudocheiridae: ( ring-tailed possums and allies) *** Family Tarsipedidae: ( honey possum) ** Superfamily Phalangeroidea *** Family Burramyidae: ( pygmy possums) *** Family Phalangeridae: ( brushtail possums and cuscuses) *** Family † Ektopodontidae: ( sprite possums) * Suborder Vombatiformes ** Family Phascolarctidae:

(one species) ** Family Vombatidae:

s (three species) ** Family † Diprotodontidae: ( giant wombats) ** Family † Ilariidae ** Family † Maradidae ** Family † Palorchestidae: ( marsupial tapirs) ** Family † Thylacoleonidae: ( marsupial lions) ** Family † Wynyardiidae † means extinct family, genus or species

References

{{Authority control Mammal orders Extant Chattian first appearances Taxa named by Richard Owen

Characteristics

Fossil record

Classification

See also

References