''Liyamayi dayi'' is a mammal species of the

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 ...

family known from fossils located at the

Riversleigh World Heritage Area Riversleigh World Heritage Area is Australia's most famous fossil location, recognised for the series of well preserved fossils deposited from the Late Oligocene to more recent geological periods. The fossiliferous limestone system is located n ...

in northeast Australia. The discovery of the specimens was identified as deposited around fifteen million years ago, revising the earliest record of this peramelemorphian lineage from those of species that existed around ten million years later.

Taxonomy

A fossil species assigned to a new genus, ''Liyamayi'', in a description by researchers at the Riversleigh fossil area, K. J. Travouillon, S. J. Hand, M. Archer and K. H. Black, who identified distinctions in the dentition from other named genera, for a new species of

Riversleigh fauna Riversleigh fauna is the collective term for any species of animal identified in fossil sites located in the Riversleigh World Heritage Area. Faunal zones The presence of the Riversleigh in the Oligo-Miocene has been exceptionally well preserve ...

was published in 2014, the authors proposing the specific epithet for Robert Day in gratitude for support toward the research project. The gender of the genus name ''Liyamayi'' is stated to be masculine, and combines two terms from the

Waanyi The Waanyi people, also spelt Wanyi, Wanji, or Waanji, are an Aboriginal Australian people from south of the Gulf of Carpentaria in Queensland and the Northern Territory. Language Although the Waanyi language was thought to be extinct, the 2016 ...

language, spoken by peoples of the Riversleigh region, ''liya'' and ''mayi'', in reference to the "round tooth" that distinguishes the genus.

Description

A genus known by a single species, ''Liyamayi dayi'' is recognised as an early representative of a thylacomyid lineage that is separated from the

Chaeropodidae ''Chaeropus'', known as the pig-footed bandicoots, is a genus of small Marsupial, marsupials that became extinct during the 20th century. They were the only members of the family Chaeropodidae in order Peramelemorphia (bandicoots and bilbies), wi ...

, a family represented by the modern pig-footed bandicoots ''

Chaeropus ''Chaeropus'', known as the pig-footed bandicoots, is a genus of small marsupials that became extinct during the 20th century. They were the only members of the family Chaeropodidae in order Peramelemorphia (bandicoots and bilbies), with unusua ...

'', and the

Peramelidae The marsupial family Peramelidae contains 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 described. O ...

family of extant bandicooots. The estimates of body mass are from around 650 grams to less than one kilogram. The

holotype A holotype (Latin: ''holotypus'') is a single physical example (or illustration) of an organism used when the species (or lower-ranked taxon) was formally described. It is either the single such physical example (or illustration) or one of s ...

and only known specimen is a section of the animal's right maxillary with remaining evidence of intact molars M1–M3 and

alveoli Alveolus (; pl. alveoli, adj. alveolar) is a general anatomical term for a concave cavity or pit. Uses in anatomy and zoology * Pulmonary alveolus, an air sac in the lungs ** Alveolar cell or pneumocyte ** Alveolar duct ** Alveolar macrophage * M ...

of the fourth molar.

Distribution and habitat

The distribution of ''Liyamayi dayi'' is restricted to Riversleigh, an area rich in series of well preserved fossil mammals. The only known location of specimens is Rick's Sausage Site at Riversleigh, a poorly studied site which is probably middle Miocene, Riversleigh Faunal Zone C approximately 15 mya, at that time part of the wet rainforest that dominated the Riversleigh area. The fauna discovered at the same site support the evidence of a local wet rainforest environment. Finding evidence of the lineage, known from other sites and thought to have diversified in other regions, implies they were establishing themselves in the region as the local ecology responded to a drier climate.

References

{{taxonbar, from=Q66001997, from2=Q66002153 Riversleigh fauna Peramelemorphs Mammals described in 2014 Prehistoric marsupial genera Fossil taxa described in 2014