'Thingodonta' is the colloquial name given to a bizarre order of extinct Australian marsupials, first described in 1988 and known only from the Oligo-Miocene deposits of Riversleigh, northeastern Australia. In biology and ecology, extinction is the ceasing of existence of a species or group of species. ... Orders Didelphimorphia Paucituberculata Microbiotheria Dasyuromorphia Peramelemorphia Notoryctemorphia Diprotodontia Marsupials are mammals in which the female typically has a pouch (called the marsupium, from which the name Marsupial derives) in which it rears its young through early infancy. ... The Oligocene epoch is a geologic period of time that extends from about 34 million to 23 million years before the present. ... The Miocene epoch is a period of time that extends from about 23 to 5. ... Riversleigh, in North West Queensland, is a 100 km² area containing fossil remains of ancient mammals. ...

A single genus, Yalkaparidon (from an aboriginal word for boomerang, alluding to the boomerang shape of its molars when seen in occlusal view, and the Greek word for tooth) and two species, Y. coheni and Y. jonesi, have so far been described. Numerous isolated teeth and jaw bones of Yalkaparidon are known, but only a single skull (of Y. coheni) has so far been recovered. For other uses of the word, please see Genus (disambiguation). ... Australian Aborigines are the indigenous peoples of Australia. ... A typical wooden returning boomerang A boomerang is a simple wooden implement used for various purposes. ... Molar may refer to: Molar (tooth), the fourth kind of tooth in mammals. ... In biology, a species is one of the basic units of biodiversity. ... It has been suggested that this article or section be merged with mandible. ... It has been suggested that temporal fenestra be merged into this article or section. ...

These specimens of Yalkaparidon exhibit a fascinating melange of characters: the molars are zalambdodont (a distinctive tooth type also found in the marsupial mole Notoryctes, the living placental 'insectivores' Solenodon, tenrecs and golden moles, as well as a number of fossil groups); the incisors are very large and hypselodont (open-rooted and hence ever-growing, similar to those of rodents); the basicranial region of the only known skull is very primitive, somewhat similar to those of plesiomorphic bandicoots. The zalambdodont molars appear to link it to notoryctid marsupial moles, but detailed study of the teeth of these two groups suggests that they have evolved independently, and Yalkaparidon is anatomically otherwise very different from the marsupial moles. The incisors resemble those of diprotodontians, but no other features convincingly support this relationship, and the convergent evolution of such incisors in South American 'pseudodiprotodont' groups (such as caenolestids and polydolopimorphians) suggests that Yalkaparidon and diprotodontians may have evolved similar incisors independently. Basicranial similarities to bandicoots most likely represent shared plesiomorphic characters, and hence are not indicative of a close relationship. This does not cite its references or sources. ... Genera 17 genera, see text Moles are members of the family (Talpidae) of mammals in the order Soricomorpha that live underground, burrowing holes. ... Binomial names Notoryctes typhlops Notoryctes caurinus The marsupial moles are rare and poorly understood burrowing mammals of the deserts of western Australia. ... Any organism with a diet that consists chiefly of insects and similar small creatures is an insectivore. ... Species Solenodon [Atopogale] cubanus Solenodon paradoxus The family Solenodontidae are nocturnal, burrowing, insectivorous mammals. ... Subfamilies  Oryzorictinae  Potamogalinae  Tenrecinae Tenrecidae (common name tenrecs) is a family of mammals found on Madagascar and parts of western Africa. ... Genera  Eremitalpa  Chrysospalax  Chrysochloris  Cryptochloris  Carpitalpa  Chlorotalpa  Calcochloris  Amblysomus  Neamblysomus Golden moles are small, insectivorous burrowing mammals native to southern Africa. ... An ammonite fossil Eocene fossil fish of the genus Knightia Petrified wood fossil formed through permineralization. ... Incisors are the first kind of tooth in heterodont mammals. ... Suborders Sciuromorpha Castorimorpha Myomorpha Anomaluromorpha Hystricomorpha Rodentia is an order of mammals also known as rodents. ... This cladogram shows the relationship among various insect groups. ... Families and Genera Chaeropodidae Chaeropus Peramelidae Isoodon Perameles Peroryctes Echymipera Microperoryctes Rhynchomeles A bandicoot is any of about 20 species of small to medium-sized, terrestrial marsupial omnivores in the order Peramelemorphia. ... This article is about evolution in biology. ...

For these reasons, Yalkaparidon is currently placed in its own family, Yalkaparidontidae, and order, Yalkaparidontia; this placement would make this the only order of Australian marsupials known to have gone extinct. However, Frederick Szalay suggested in his 1994 book 'Evolutionary History of the Marsupials and an Analysis of Osteological Characters' that Yalkaparidon is indeed a diprotodontian (as evinced by its incisors), albeit one that retains a highly primitive basicranium. In biological classification, family (Latin: familia, plural familiae) is 1) a rank or 2) a taxon in that rank. ... Scientific classification or biological classification refers to how biologists group and categorize extinct and living species of organisms. ...

The exact function of its unusual dentition remains obscure, and suggestions that it may have fed on worms (based on the similarities of its molars to those of worm-eating tenrecs), caterpillars or eggs are tenuous. However, its source of food presumably had a hard outer covering (necessitating use of the large incisors) but relatively soft interior, as zalambdodont molars cannot crush food items. Dentition is the development of teeth and their arrangement in the mouth. ... For other uses, see Worm (disambiguation). ... The striking caterpillar of the Emperor Gum Moth A caterpillar is the larval form of a lepidopteran (a member of the insect order comprised of butterflies and moths). ... In most birds and reptiles, an apple (Latin ovum) is the zygote, resulting from fertilization of the ovum. ...

Future insights into the evolutionary relationships, functional morphology and lifestyle of Yalkaparidon must await more detailed study. It remains one of the most enigmatic members of Australia's unique mammalian fauna. Comparative anatomy is the study of similarities and differences in organisms. ... Fauna is a collective term for animal life of any particular region or time. ...

References

• Mikko's Phylogeny Archive - Australidelphia - Australian marsupials