The order Peramelemorphia includes the

bandicoot Bandicoots are a group of more than 20 species of small to medium-sized, terrestrial, largely nocturnal marsupial omnivores in the order Peramelemorphia. They are endemic to the Australia–New Guinea region, including the Bismarck Archipelago t ...

s and bilbies; it equates approximately to the mainstream of marsupial omnivores. All members of the order are

endemic Endemism is the state of a species being found in a single defined geographic location, such as an island, state, nation, country or other defined zone; organisms that are indigenous to a place are not endemic to it if they are also found else ...

to the twin land masses of Australia-

New Guinea New Guinea (; Hiri Motu: ''Niu Gini''; id, Papua, or , historically ) is the world's second-largest island with an area of . Located in Oceania in the southwestern Pacific Ocean, the island is separated from Australia by the wide Torr ...

and most have the characteristic bandicoot shape: a plump, arch-backed body with a long, delicately tapering snout, very large upright ears, relatively long, thin legs, and a thin tail. Their size varies from about 140 grams up to 4 kilograms, but most species are about one kilogram.

Phylogeny

Placement within Marsupialia

The position of the Peramelemorphia within the marsupial family tree has long been puzzling and controversial. There are two morphological features in the order that appear to show a clear evolutionary link with another marsupial group: the type of foot, and the teeth. Unfortunately, these clear signposts point in opposite directions. All members of the order are polyprotodont (have several pairs of lower front teeth)—in the case of the Peramelemorphia, three pairs. This suggests that they have evolved within

Dasyuromorphia 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 omn ...

(marsupial carnivores). On the other hand, they also have an unusual feature in their feet: the second and third toes are fused together. This condition is called

syndactyl In biology, dactyly is the arrangement of digits (fingers and toes) on the hands, feet, or sometimes wings of a tetrapod animal. It comes from the Greek word δακτυλος (''dáktylos'') = "finger". Sometimes the ending "-dactylia" is use ...

y, and is characteristic of the

Diprotodontia Diprotodontia (, from Greek "two forward teeth") is the largest extant order of marsupials, with about 155 species, including the kangaroos, wallabies, possums, koala, wombats, and many others. Extinct diprotodonts include the hippopotamus-sized ...

(the order of marsupial herbivores that includes

kangaroo Kangaroos are four 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 ...

wombat Wombats are short-legged, muscular quadrupedal marsupials that are native to Australia. They are about in length with small, stubby tails and weigh between . All three of the extant species are members of the family Vombatidae. They are ada ...

possums Possum may refer to: Animals * Phalangeriformes, or possums, any of a number of arboreal marsupial species native to Australia, New Guinea, and Sulawesi ** Common brushtail possum (''Trichosurus vulpecula''), a common possum in Australian urban a ...

, and many others). Attempts to resolve this puzzle include the view that the bandicoot group evolved from the carnivores, retaining the polyprotodont dentition, and independently evolving a syndactyl hind foot; the contrary view that syndactyly is so unusual that it is unlikely to have evolved twice and therefore the bandicoot group must have evolved from a possum-like diprotodont creature, and re-evolved its extra teeth. A third view suggests that the bandicoot group evolved from a primitive carnivore, developed the syndactylous hind foot as a specialisation for climbing, and the diprotodonts then split off and evolved the two-tooth jaw that gives them their name. Recent molecular level investigations do not so far appear to have resolved the puzzle, but do strongly suggest that whatever the relationship of the bandicoot group to the other marsupial orders may be, it is a distant one.

Relationships within Peramelemorphia

Recent molecular analyses have resulted in a

phylogenetic In biology, phylogenetics (; from Greek φυλή/ φῦλον [] "tribe, clan, race", and wikt:γενετικός, γενετικός [] "origin, source, birth") is the study of the evolutionary history and relationships among or within groups o ...

reconstruction of the members of Peramelemorphia with quite strong support. The most basal split separates

Thylacomyidae ''Macrotis'' is a genus of desert-dwelling marsupial omnivores known as bilbies or rabbit-bandicoots; Unabridged they are members of the order Peramelemorphia. At the time of European colonisation of Australia, there were two species. The ...

(''

Macrotis ''Macrotis'' is a genus of desert-dwelling marsupial omnivores known as bilbies or rabbit-bandicoots; Unabridged they are members of the order Peramelemorphia. At the time of European colonisation of Australia, there were two species. The ...

'') from all other bandicoots. Probably the next to diverge was the recently extinct Chaeropodidae (''

Chaeropus ''Chaeropus'', known as the pig-footed bandicoots, is a genus of small mammals that became extinct during the 20th century. They were unique marsupials, of the order Peramelemorphia (bandicoots and bilbies), with unusually thin legs, yet were a ...

''). The remaining taxa comprise the

Peramelidae The marsupial family Peramelidae contains all of the extant bandicoots. They are found throughout Australia and New Guinea, with at least some species living in every available habitat, from rainforest to desert. Four fossil peramelids are descri ...

, which divides into subfamilies

Peramelinae The marsupial family Peramelidae contains all of the extant bandicoots. They are found throughout Australia and New Guinea, with at least some species living in every available habitat, from rainforest to desert. Four fossil peramelids are descr ...

(''

Isoodon The short-nosed bandicoots (genus ''Isoodon'') are members of the order Peramelemorphia. These marsupials can be found across Australia, although their distribution can be patchy. Genetic evidence suggests that short-nosed bandicoots diverged fro ...

'' and ''

Perameles ''Perameles'' is a genus of marsupials of the order Peramelemorphia. They are referred to as long-nosed bandicoots or barred bandicoots. ''Perameles'', or ‘pouched badger’, is a hybrid word, from the Greek (πήρα, ‘pouch, bag’) and ...

'') and a clade in which the

Echymiperinae The marsupial family Peramelidae contains all of the extant bandicoots. They are found throughout Australia and New Guinea, with at least some species living in every available habitat, from rainforest to desert. Four fossil peramelids are descri ...

('' Echymipera'' and '' Microperoryctes'') form a sister group to

Peroryctinae The New Guinean long-nosed bandicoots (genus ''Peroryctes'') are members of the order Peramelemorphia. They are small to medium-sized marsupial omnivores native to New Guinea. Two fossil A fossil (from Classical Latin , ) is any preser ...

('' Peroryctes''):

Fossil record

Many specimens of modern peramelemorphian (e.g. ''Perameles'' spp. and ''Isoodon'' spp.) have been recovered in the fossil record from

Pleistocene The Pleistocene ( , often referred to as the ''Ice age'') is the geological epoch that lasted from about 2,580,000 to 11,700 years ago, spanning the Earth's most recent period of repeated glaciations. Before a change was finally confirmed in ...

and

Holocene The Holocene ( ) is the current geological epoch. It began approximately 11,650 cal years Before Present (), after the Last Glacial Period, which concluded with the Holocene glacial retreat. The Holocene and the preceding Pleistocene togeth ...

fossil localities. However, very few fossil species have been recovered to date. The first species of fossil peramelemorphian was described by R. A. Stirton in 1955. The specimen Stirton described was a partial lower jaw from the

Tirari Desert The Tirari Desert is a desert in the eastern part of the Far North region of South Australia. It stretches 212 km from north to south and 153 km from east to west. Location and description The Tirari Desert features salt lakes and ...

in Central Australia,

Pliocene The Pliocene ( ; also Pleiocene) is the epoch in the geologic time scale that extends from 5.333 million to 2.58Bluff Downs fossil site, Allingham Formation, in northern

Queensland ) , nickname = Sunshine State , image_map = Queensland in Australia.svg , map_caption = Location of Queensland in Australia , subdivision_type = Country , subdivision_name = Australia , established_title = Before federation , establishe ...

, also Pliocene in age. The tooth was similar to that of species of ''Perameles'', and was therefore named ''

Perameles allinghamensis ''Perameles allinghamensis'', the Bluff Downs bandicoot, is a small extinct bandicoot that lived in Australia 4 million years ago in the Pliocene period. It was discovered at the Bluff Downs fossil site in northern Queensland ) , nickname ...

''. In 1995, the first

Miocene The Miocene ( ) is the first epoch (geology), 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 mea ...

species was described from Riversleigh, and was named '' Yarala burchfieldi'' by Dr Jeannette Muirhead. The species was represented by several upper and lower jaws, which were smaller than any living bandicoots and had a very primitive dentition. A skull was later recovered in 2000, the first for any fossil peramelemorphian to date. Features of the skull and dentition suggested that ''Yarala burchfieldi'' was distinct from other peramelemorphians, and for this reason, a new Superfamily

Yaraloidea ''Yarala'' is a genus of fossil mammals that resemble contemporary bandicoots. The superfamily Yaraloidea and family Yaralidae were created following the discovery of the type species ''Yarala burchfieldi'' in 1995, on the basis that it lacks sy ...

and Family Yaralidae were erected to classify this species. In 1997, Muirhead, Dawson and Archer described a new species of ''Perameles'', ''

Perameles bowensis ''Perameles bowensis'' is an extinct Pliocene-aged species of bandicoot. Fossils have been found in the Wellington Caves of New South Wales.Muirhead, J., Dawson, L. & Archer, M. 1997. Perameles bowensis, a new species of ''Perameles'' (Peramelomo ...

'', from teeth recovered from two Pliocene fossil localities, Bow and Wellington Caves. The same species was later reported in 2000 from

Chinchilla, Queensland Chinchilla is a rural town and locality in the Western Downs Region, Queensland, Australia. In the , the locality of Chinchilla had a population of 6,612 people. Chinchilla is known as the 'Melon Capital of Australia', and plays host to a Mel ...

, by Mackness and colleagues. In 2002, Price described a new species ''

'', ''

Perameles sobbei ''Perameles'' is a genus of marsupials of the order Peramelemorphia. They are referred to as long-nosed bandicoots or barred bandicoots. ''Perameles'', or ‘pouched badger’, is a hybrid word, from the Greek (πήρα, ‘pouch, bag’) and ...

'', from the

Darling Downs The Darling Downs is a farming region on the western slopes of the Great Dividing Range in southern Queensland, Australia. The Downs are to the west of South East Queensland and are one of the major regions of Queensland. The name was general ...

(Pleistocene in age), south-eastern Queensland. This species was represented by a lower jaw and a few isolated lower molars. Additional material were later described in 2005 from the same site, including upper molars. A second species of ''Yarala'', ''Yarala kida'', was described in 2006 by Schwartz. This species was recovered from Kangaroo Well, a late Oligocene site from the

Northern Territory The Northern Territory (commonly abbreviated as NT; formally the Northern Territory of Australia) is an Australian territory in the central and central northern regions of Australia. The Northern Territory shares its borders with Western Aust ...

in Australia. This species is thought to be even more primitive than ''Yarala burchfieldi''. The second fossil skull of any fossil peramelemorphian was also recovered from Miocene sites of Riversleigh. In fact, more than one skull of this new species was found (and several lower and upper jaws), and was significantly different from any other bandicoot to erect a new genus, ''

Galadi ''Galadi'' is an extinct genus of predatory bandicoot from Oligo-Miocene deposits of Riversleigh, northwestern Queensland, Australia. It was first named by K.J. Travouillon, Y. Gurovich, R.M.D. Beck and J. Muirhead in 2010 and the type species ...

''. The species was named ''Galadi speciosus'' by Travouillon and colleagues. It was short-snouted unlike modern bandicoots suggesting that it was more carnivorous than its omnivorous modern relatives. Its relationship to other bandicoots is unclear, but it was likely to be less primitive than ''Yarala'' but more primitive than living bandicoots. An additional three species of ''Galadi'' were later described in 2013 and named ''Galadi grandis'', ''Galadi amplus'' and ''Galadi adversus''. Gurovich et al. (2013) described a new species of mouse-sized bandicoot from Riversleigh and from Kutjamarpu, Southern Australia. The species, named '' Bulungu palara'', is represented by a skull and several lower and upper jaws. Two other species in this

genus Genus ( plural genera ) is a taxonomic rank used in the biological classification of living and fossil organisms as well as viruses. In the hierarchy of biological classification, genus comes above species and below family. In binomial nom ...

were also described from the Etadunna Formation in South Australia, ''Bulungu muirheadae'' which was the oldest fossil bandicoot recovered as of 2013 (about 24 million years old), and ''Bulungu campbelli''. The oldest modern bandicoot (peramelid) and the oldest bilby (Thylacomyid) were later discovered by Travouillon et al., 2014 from Riversleigh World Heritage Area, from middle Miocene fossil deposits (around 15 million years old). The peramelid, ''

Crash bandicoot ''Crash Bandicoot'' is a video game franchise originally developed by Naughty Dog as an exclusive for Sony's PlayStation console. It has seen numerous installments created by various developers and published on multiple platforms. The series c ...

'', was named after the famous video game character and is only represented by a single upper jaw. The bilby, '' Liyamayi dayi''named after geologist and philanthropist Robert Day, is only known from 3 teeth (2 upper molar, 1 lower molar). The first record of sexual dimorphism (difference in size between males and females) in a fossil bandicoot was reported from two new species from Riversleigh (Travouillon et al. 2014). Named '' Madju variae'' and '' Madju encorensis'', they are closely related to modern bandicoots, but do not fall in any modern family, as did ''

'' and '' Bulungu''. Instead they are classified as Perameloid, with all known Peremelemorphian, to the exclusion of Yaralids. '' Madju variae'' is also unusual in preserving an ontogenetic series (age series from pouch young to adult), the second of any fossil marsupial mammal in Australia. The study of this ontogenetic series lead researchers to think that '' Madju variae'' developed slow than modern bandicoots, much more like a bilby, and therefore the rapid development of modern bandicoots must have evolved after the middle Miocene, when Australia started to become more arid.Travouillon, K. J., Archer, M., Hand, S. J. and Muirhead, J., 2014. Sexually dimorphic bandicoots (Marsupialia: Peramelemorphia) from the Oligo-Miocene of Australia, first cranial ontogeny for fossil bandicoots and new species descriptions. ''Journal of Mammalian Evolution''. doi:10.1007/s10914-014-9271-8

References

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Peramelemorphia
{{Authority control Mammal orders Extant Chattian first appearances Taxa named by Florentino Ameghino