An element pretty unheard of and extremely rare, identified in the tiny fish teeth has offered a clue to the University of Florida geologists in estimating the period when the passage between Atlantic and Pacific might have opened up. This has happened obviously millions of years ago, during warmer times, when ocean current was formed around the pole and is thought to have contributed in great measure to Antarctica's metamorphosis from a forested continent to an icy one.
Fish teeth contain a mineral called apatite, which absorbs the neodymium on the seafloor. This is probably the reason why UF researchers chose to study fish teeth. The geologists obtained the teeth from sedimentary cores, in the South Atlantic Ocean. Measurements using a technique called thermal ionization mass spectrometry revealed the teeth neodymium had a signature of the Pacific, indicating at least a surface connection between the oceans. The presence of neodymium with a Pacific signature in the deep Atlantic suggests that Pacific surface waters flowed into the South Atlantic, where they cooled and sank.
According to the Geologists, the opening of passage could have caused the plunge in temperatures because the circumpolar current would have isolated Antarctica from warm subtropical water carrying heat from the tropics. In addition, the circumpolar current sets up conditions leading to upwelling of cold, nutrient-rich water. This in turn may have spurred the growth of algae and higher forms of biological life, which consumed carbon dioxide, reducing levels and contributing to cooling the continent's climate.
Source: Eureka Alert