Palaeontology

Antarctica provides a unique opportunity to study a sedimentary sequence that contains a record of changes from icehouse to greenhouse conditions. This succession of upper Palaeozoic to Mesozoic sedimentary rocks contains vertebrate, invertebrate, plant and trace fossils. The fauna and flora found here are also proof that Antarctica was once part of Godwana, the time of fragmentation of the supercontinent.

One of the most important fossils to be found in the Transantarctic Mountain Range is that of the bones of the Permian aquatic Therapsid reptile known as Lystrosaurus. Found near the peak of the Transantarctic Mountain Range overlooking the Beardman Glacier in a layer of soil more than two hundred million years old. Lystrosaurus was a mammal like reptile about the size of a dog and resembling a small hippo. Similar bones have been found in Africa and India indicating the connection between the Antarctic, African and Indian continents within the supercontinent of Gondwana. Lystrosaurus was believed to have similar habits to that of the present day hippopotamus, living in swamps and wetlands and browsing on vegetation, providing proof that Antarctica was once a warm green continent covered in trees and plants. Also supported by the evidence of coal reserves found within the range.

Plant microfossil assemblages have been found in the Transantarctic Mountain Range which have been shown to reflect a number of different floras ranging in age from Late Carboniferous through Permain and Triassic. Subdivisions within these floras enabled the correlation of sequences in different areas of the Transantarctic Mountain Range and also with the divisions of the Australian palynologic successions (Kyle and Schope, 1982)

Fossil wood and leaves of Nothofagus beardmorensis Hill, Harwood and Webb have been found within the Sirius Group in Antarctica, a sequence of Pliocene glacial sediments that outcrop in the Transantarctic Mountain Range. Growth forms and tree rings in the fossilized wood and the morphology of the leaves indicate that these plants were deciduous dwarf trees (though known to be fully grown adults) that had developed a postrate habit with branches spreading out across the ground surface. Comparisons with similar plants living at high latitudes today has suggested a mean annual temperature for the Transantarctic Mountain Range at that time was about -50 c, with very short summer growing seasons.

All the fossil woods, ferns, fish amphibians and reptiles that are found within the Transantarctic Mountain Range and the Antarctic continent are seen to disappear about twenty five million years ago. This is known to correspond to a period of cooling following the formation of the Antarctic Circumpolar Current some twenty eight million years ago, which isolated the continent from the warmer oceans of the world.

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