Argentine Antarctica mainland. Argentina was the only nation to have an Antarctic base for 40 years until the British built a base on the same islands. Argentina bases its claims on this sector of Antarctica on the following grounds: Argentina's claim to the Antarctic Peninsula overlaps with the Antarctic claims of Chile, 53°W to 90°W, and the UK claims, 20°W to 80°W. Currently, there are no attempts by Argentina or any other country to enforce territorial claims in Antarctica. See List of Antarctic territorial claims. None of these claims have international recognition and have been suspended by the Antarctic Treaty in 1961.
Antarctica cooling of Antarctica occurred stepwise, as the continental spread changed the oceanic currents from longitudinal equator-to-pole temperature-equalising currents to latitudinal currents that preserved and accentuated latitude temperature differences. Africa separated from Antarctica in the Jurassic, around 160 Ma, followed by the Indian subcontinent in the early Cretaceous (about 125 Ma). By the end of the Cretaceous, about 66 Ma, Antarctica (then connected to Australia) still had a subtropical climate and flora, complete with a marsupial fauna. In the Eocene epoch, about 40 Ma Australia-New Guinea separated from Antarctica, so that latitudinal currents could isolate Antarctica from Australia, and the first