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The re-colonization of Antarctica: stories of penguins and seals, sentinels of climate change in the last ten thousand years. During the Late Pleistocene the Antarctic glacial system expanded and advanced on the coastal margin of the continent forcing penguins, seals and other animals nesting in the deglaciated areas to migrate toward refuge areas located at northern latitudes. The deglaciation that followed the last glacial maximum, in the Ross Sea area, was accomplished around 8000 years ago, freeing the Antarctic coasts that were re-colonized by Adélie penguins and elephant seals. These two species have coexisted, even alternating, in the deglaciated areas of the coastal strip for several millennia. In the ornithogenic soils of the abandoned penguin colonies and in the breeding sites of the elephant seals, recently discovered on the Holocene raised beaches, a precious heritage of organic remains is preserved, allowing us to study different aspects of recent environmental history. The phases of colonization and coexistence between penguins and elephant seals are very complex and reflect the climatic-environmental variations that have characterized the Antarctic scenario for several thousand of years. Penguins and elephant seals, sensitive sentinels of the Antarctic ecosystem, are now playing an important role in the Southern Ocean scenario, interpreting the dramatic role of bellwether of climate change.