| Tingamarra Temporal range: | |
|---|---|
Scientific classification  | |
| Domain: | Eukaryota |
| Kingdom: | Animalia |
| Phylum: | Chordata |
| Class: | Mammalia |
| Subclass: | Theria |
| Genus: | † Tingamarra Godthelp et al., 1992 |
| Species: | †T. porterorum |
| Binomial name | |
| †Tingamarra porterorum Godthelp et al., 1992 | |
Tingamarra is an extinct genus of mammals from Australia. Its age, lifestyle, and relationships remain controversial.
Tingamarra was discovered in 1987, when a single tooth was found at the Murgon fossil site in south-eastern Queensland. An ankle bone and an ear bone found at Murgon may also belong to this animal.
Holotype: QMF20564, isolated right lower molar, probably an M2 or M3. [1]
1. Non-twinned hypoconulid and entoconid.
2. Lack of a well developed buccal postcingulid.
3. Lack of anteroposteriorly compressed trigonid.
4. Broadly open trigonid.
5. Lingually situated paraconid that is also well anterior to the protoconid.
Tingamarra is believed to be a small (about 20 cm from head to tail) ground-dwelling mammal that ate insects and fruit.
The age of Murgon fossils was determined as the early Eocene. [1] If it is correct, then these fossils are the oldest Australian mammal ones.
By the shape of the found tooth, Tingamarra was first classified as a condylarth. [1] This is a primitive order of mammals which are ancestral to modern ungulates. If this interpretation is correct, Tingamarra appears to be the only land-based placental mammal to have arrived to Australia before about 8 million years ago. The only other native placental mammals in Australia are rodents and dingos (which arrived here more recently), and bats (which presumably flew in).
Most Australian mammals are marsupials instead. Before Tingamarra was found, it was hypothesised that marsupials had done well in Australia only because for many millions of years they had no placentals to compete with. [1]
However, both the age and placental nature of Tingamarra were subsequently challenged by other researchers. Woodburne et al. [2] argued that: 1) the true age of Murgon fossil site is the late Oligocene, and 2) that indeed neither shape nor microstructure of the tooth do not allow to distinguish whether Tingamarra was marsupial or placental. Then Rose [3] concluded that at present there is no undoubted evidence to change the established views.
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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", from mola, millstone and dens, tooth. Molars show a great deal of diversity in size and shape across the mammal groups. The third molar of humans is sometimes vestigial.
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The natural history of Australia has been shaped by the geological evolution of the Australian continent from Gondwana and the changes in global climate over geological time. The building of the Australian continent and its association with other land masses, as well as climate changes over geological time, have created the unique flora and fauna present in Australia today.
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UA 8699 is a fossil mammalian tooth from the Cretaceous of Madagascar. A broken lower molar about 3.5 mm (0.14 in) long, it is from the Maastrichtian of the Maevarano Formation in northwestern Madagascar. Details of its crown morphology indicate that it is a boreosphenidan, a member of the group that includes living marsupials and placental mammals. David W. Krause, who first described the tooth in 2001, interpreted it as a marsupial on the basis of five shared characters, but in 2003 Averianov and others noted that all those are shared by zhelestid placentals and favored a close relationship between UA 8699 and the Spanish zhelestid Lainodon. Krause used the tooth as evidence that marsupials were present on the southern continents (Gondwana) as early as the late Cretaceous and Averianov and colleagues proposed that the tooth represented another example of faunal exchange between Africa and Europe at the time.
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Yingabalanara is an extinct mammal from the Miocene of Australia. Known only from a few teeth, its affinities with other mammal groups remain unresolved.
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