Peramelemorphia

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Peramelemorphia
Temporal range: Late Oligocene–Recent
Taxidermied Bandicoot.jpg
A short-nosed bandicoot (Isoodon spp.)
Scientific classification
Kingdom: Animalia
Phylum: Chordata
Class: Mammalia
Infraclass: Marsupialia
Superorder: Australidelphia
Order: Peramelemorphia
Ameghino, 1889
Families

Yaralidae
Thylacomyidae
Chaeropodidae
Peramelidae

The order Peramelemorphia includes the bandicoots and bilbies: it equates approximately to the mainstream of marsupial omnivores. All members of the order are endemic to the twin land masses of Australia-New Guinea 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,[1] but most species are about the weight of a half-grown kitten: somewhere around one kilogram.

Phylogeny[edit]

Placement within Marsupialia[edit]

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.[2]

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 (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 syndactyly, and is characteristic of the Diprotodontia (the order of marsupial herbivores that includes kangaroos, wombats, possums, and many others).[3]

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.[4]

Relationships within Peramelemorphia[edit]

Recent molecular analyses have resulted in a phylogenetic reconstruction of the members of Peramelemorphia with quite strong support. The most basal split separates Thylacomyidae (Macrotis) from all other bandicoots. Probably the next to diverge was the recently extinct Chaeropodidae (Chaeropus). The remaining taxa comprise the Peramelidae, which divides into subfamilies Peramelinae (Isoodon and Perameles) and a clade in which the Echymiperinae (Echymipera and Microperoryctes) form a sister group to Peroryctinae (Peroryctes):[4]

Peramelemorphia
Thylacomyidae

Macrotis



†Chaeropodidae

Chaeropus


Peramelidae
Peramelinae

Isoodon



Perameles




Echymiperinae

Echymipera



Microperoryctes



Peroryctinae

Peroryctes






Fossil record[edit]

Many specimens of modern peramelemorphian (e.g. Perameles spp. and Isoodon spp.) have been recovered in the fossil record from Pleistocene and Holocene fossil localities.[5] 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 in Central Australia, Pliocene in age. The lower jaw morphology suggested a relationship with bilbies (Family Thylacomyidae), and was named Ischnodon australis.[6]

It is not until 1976 that Archer and Wade described the next fossil bandicoot. A single upper molar was recovered from the Bluff Downs fossil site, Allingham Formation, in northern Queensland, also Pliocene in age. The tooth was similar to that of species of Perameles, and was therefore named Perameles allinghamensis.[7]

In 1995, the first Miocene 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.[8] 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 and Family Yaralidae were erected to classify this species.[9]

In 1997, Muirhead, Dawson and Archer described a new species of Perameles, Perameles bowensis, from teeth recovered from two Pliocene fossil localities, Bow and Wellington Caves.[10] The same species was later reported in 2000 from Chinchilla, Queensland by Mackness and colleagues.[11] In 2002, Price described a new species Perameles, Perameles sobbei, from the Darling Downs (Pleistocene in age), south-eastern Queensland. This species was represented by a lower jaw and a few isolated lower molars.[12] Additional material were later described in 2005 from the same site, including upper molars.[13]

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 in Australia. This species is thought to be even more primitive than Yarala burchfieldi.[14]

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. 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.[15] An additional three species of Galadi were later described in 2013 and named Galadi grandis, Galadi amplus and Galadi adversus.[16]

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.[17] Two other species in this genus 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.[18]

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 was named after the famous video game character and is only represented by a single upper jaw. The bilby, Liyamayi dayinamed after geologist and philanthropist Robert Day, is only known from 3 teeth (2 upper molar, 1 lower molar).[19]

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 Galadi and Bulungu (genus). 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.[20]

References[edit]

  1. ^ Aplin, K.P., Helgen, K.M., Lunde, D.P., 2010. A review of Peroryctes broadbenti, the giant bandicoot of Papua New Guinea. . American Museum novitates 3696, 1-41.
  2. ^ Gordon, G., Hulbert, A.J., 1989. Peramelidae, In: Walton, D.W. (Ed.), Fauna of Australia. . Australian Government Publishing Service, Canberra, pp. 603–624.
  3. ^ Strahan, R. 1995. Mammals of Australia. Washington, D.C.: Smithsonian Institution Press.
  4. ^ a b Meredith, Robert W.; Westerman, Michael; Springer, Mark S. (2008). "A timescale and phylogeny for "Bandicoots" (Peramelemorphia: Marsupialia) based on the sequences for five nuclear genes". Molecular Phylogenetics and Evolution 47 (1): 1–20. doi:10.1016/j.ympev.2008.01.002. PMID 18328736. 
  5. ^ Rich, T. H, Archer, M., Hand, S. J., Godthelp, H., Muirhead, J., Pledge, N. S., Flannery, T. F., Woodburne, M. O., Case, J. A., Teford, R. H., Turnbull, W. D., Lundelius, E. L.jr., Rich, L. S. V., Whitelaw, M. J., Kemp, A., & Rich, P. V. 1991. Australian Mesozoic and Tertiary terrestrial mammal localities, Appendix 1. Pp. 1005-1058 in P. Vickers-Rich, Monaghan J. M., R. F. Baird & T. H. Rich (eds), Vertebrate Palaeontology of Australia. Pioneer Design Studio and Monash University Publications Commiitee, Melbourne.
  6. ^ Stirton, R. A. 1955. Late Tertiary marsupials from South Australia. Records of the South Australian Museum, 11, 247– 267.
  7. ^ Archer, M. & Wade, M. 1976. Results of the Ray E. Lemley expeditions, part 1: The Allingham Formation and a new Pliocene vertebrate fauna from northern Queensland. Memoirs of the Queensland Museum, 17, 54–58.
  8. ^ Muirhead, J. & Filan, S. L. 1995. Yarala burchfieldi, a plesiomorphic bandicoot (Marsupialia, Peramelemorphia) from Oligo-Miocene deposits of Riversleigh, northwestern Queensland. Journal of Paleontology, 69(1), 127-134.
  9. ^ Muirhead, J. 2000. Yaraloidea (Marsupialia, Peramelemorphia), a new superfamily of marsupial and a description and analysis of the cranium of the Miocene Yarala burchfieldi. Journal of Paleontology, 74(3), 512-523.
  10. ^ Muirhead, J., Dawson, L. & Archer, M. 1997. Perameles bowensis, a new species of Perameles (Peramelomorphia, Marsupialia) from Pliocene faunas of Bow and Wellington caves, New South Wales. Proceedings of the Linnean Society of New South Wales, 17, 163–174.
  11. ^ Mackness, B. S., Wroe, S., Muirhead, J., Wilkinson, C. & Wilkinson, D. 2000. First fossil bandicoot from the Pliocene Chinchilla Local Fauna. Australian Mammalogy, 22, 133– 136.
  12. ^ Price, G. J. 2002. Perameles sobbei, sp. nov. (Marsupialia, Peramelidae), a Pleistocene bandicoot from the Darling Downs, south-eastern Queensland. Memoirs of the Queensland Museum, 48, 193-197.
  13. ^ Price, G. J. 2005. Fossil bandicoots (Marsupialia, Peramelidae) and environmental change during the Pleistocene on the Darling Downs, southeastern Queensland, Australia. Journal of Systematic Palaeontology, 4, 347-356.
  14. ^ Schwarz, L. R. S. 2006. A new species of bandicoot from the Oligocene of northern Australia and implications of bandicoots for correlating Australian Tertiary mammal faunas. Palaeontology, 49, 991–998.
  15. ^ K.J. Travouillon; Y. Gurovich; R.M.D. Beck; J. Muirhead (2010). "An exceptionally well-preserved short-snouted bandicoot (Marsupialia; Peramelemorphia) from Riversleigh's Oligo-Miocene deposits, northwestern Queensland, Australia". Journal of Vertebrate Paleontology 30 (5): 1528–1546. doi:10.1080/02724634.2010.501463
  16. ^ K. J. Travouillon, Y. Gurovich, M. Archer, S. J. Hand and J. Muirhead (2013). "The genus Galadi: three new bandicoots (Marsupialia, Peramelemorphia) from Riversleigh’s Miocene deposits, northwestern Queensland, Australia". Journal of Vertebrate Paleontology 33 (1): 153–168. doi:10.1080/02724634.2012.713416
  17. ^ Gurovich, Y., Travouillon, K.J., Beck, R.M.D., Muirhead, J., Archer, M., 2013. Biogeographical implications of a new mouse-sized fossil bandicoot (Marsupialia: Peramelemorphia) occupying a dasyurid-like ecological niche across Australia. Journal of Systematic Palaeontology.
  18. ^ Travouillon, K.J., Beck, R.M.D., Hand, S.J., Archer, M. (2013). "The oldest fossil record of bandicoots (Marsupialia; Peramelemorphia) from the late Oligocene of Australia". Palaeontologia Electronica 16 (2): 13A 52p. 
  19. ^ Travouillon, K.J., Hand, S. J., Archer, M., and Black, K. H., 2014. Earliest modern bandicoot and bilby (Marsupialia, Peramelidae and Thylacomyidae) from the Miocene of the Riversleigh World Heritage Area, northwestern Queensland, Australia. Journal of Vertebrate Paleontology 34:375-382.
  20. ^ 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