''Yingabalanara'' is an extinct mammal from the

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 ...

of Australia. Known only from a few teeth, its affinities with other mammal groups remain unresolved.

Description

''Yingabalanara'' is known from two lower right molar teeth. The chewing surface of the tooth has two overlapping crescent-like cusps (hence the animal's name). Due to the sheer bizarreness of the teeth it's not entirely clear to which normal molar structures these cusps correspond to, being variously interpreted as

talonid The molars or molar teeth are large, flat teeth at the back of the mouth. They are more developed in mammals. They are used primarily to grind food during chewing. The name ''molar'' derives from Latin, ''molaris dens'', meaning "millstone tooth ...

trigonid The molars or molar teeth are large, flat teeth at the back of the mouth. They are more developed in mammals. They are used primarily to grind food during chewing. The name ''molar'' derives from Latin, ''molaris dens'', meaning "millstone tooth ...

s or other cusps. The molars are double-rooted, and possess what appears to be a remnant

cingulid A cingulid is a term used to describe the structure of some mammalian cheek teeth which refers to a ridge that runs around the base of the crown of a lower molar. The equivalent structure on upper molars is called the cingulum. The presence or a ...

. The overall proportions seem to suggest an animal about the size of a

rat Rats are various medium-sized, long-tailed rodents. Species of rats are found throughout the order Rodentia, but stereotypical rats are found in the genus ''Rattus''. Other rat genera include '' Neotoma'' (pack rats), '' Bandicota'' (bandicoo ...

, and the tooth morphology is consistent with

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 ...

habits. However, for obvious reasons the animal's overall appearance and morphology are unknown.

Etymology

''Yingabalanara'' is a Wanyi word meaning "two

moon The Moon is Earth's only natural satellite. It Orbit of the Moon, orbits around Earth at Lunar distance, an average distance of (; about 30 times Earth diameter, Earth's diameter). The Moon rotation, rotates, with a rotation period (lunar ...

s", in reference to the mammal's crescent-like cusps. The word is masculine in gender, as befitting the status of the predominantly masculine Australian

lunar deities A lunar deity or moon deity is a deity who represents the Moon, or an aspect of it. These deities can have a variety of functions and traditions depending upon the culture, but they are often related. Lunar deities and Moon worship can be foun ...

. The species name is an homage to

Graham Richardson Graham Frederick Richardson (born 27 September 1949) is an Australian former Labor Party politician who was a Senator for New South Wales from 1983 to 1994 and served as a Cabinet Minister in both the Hawke and Keating governments. He is c ...

, a "Commonwealth Minister for the Environment and the Arts".

Phylogeny

''Yingabalanaras molars are exceptionally unusual among mammals, rendering its exact relations as controversial. Its bizarre cusps differ radically from the normal conditions seen in

marsupial Marsupials are a diverse group of mammals belonging to the infraclass Marsupialia. They are natively found in Australasia, Wallacea, and the Americas. One of marsupials' unique features is their reproductive strategy: the young are born in a r ...

s and

placental Placental mammals (infraclass Placentalia ) are one of the three extant subdivisions of the class Mammalia, the other two being Monotremata and Marsupialia. Placentalia contains the vast majority of extant mammals, which are partly distinguished ...

s (though there are vague similarities to phyllostomid

bats Bats are flying mammals of the order Chiroptera (). With their forelimbs adapted as wings, they are the only mammals capable of true and sustained flight. Bats are more agile in flight than most birds, flying with their very long spread-out ...

), and while slightly similar to the teeth of

monotreme Monotremes () are mammals of the order Monotremata. They are the only group of living mammals that lay eggs, rather than bearing live young. The extant monotreme species are the platypus and the four species of echidnas. Monotremes are typified ...

s and other yinotheres the longer and narrower molars, presence of talonid or trigonid-like cusps and lack of lingual or buccal cingulids still set them well apart. The mammal with the most similar teeth is the

Cretaceous The Cretaceous ( ) is a geological period that lasted from about 143.1 to 66 mya (unit), million years ago (Mya). It is the third and final period of the Mesozoic Era (geology), Era, as well as the longest. At around 77.1 million years, it is the ...

North America North America is a continent in the Northern Hemisphere, Northern and Western Hemisphere, Western hemispheres. North America is bordered to the north by the Arctic Ocean, to the east by the Atlantic Ocean, to the southeast by South Ameri ...

n '' Potamotelses'', which serves of little indication since it too is of uncertain affinities. For now, ''Yingabalanara'' is included in its own order, Weirdodonta.

References

{{Taxonbar, from=Q21368854 Fossil taxa described in 1990 Riversleigh fauna Prehistoric mammals of Australia

Description

Etymology

Phylogeny

See also

References