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. 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. It was 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. 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. 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. 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. The same species was later reported in 2000 from
Chinchilla, Queensland, by Mackness and colleagues. 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. 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 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. 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 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, 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). 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. 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. ==See also==