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A new international study casts doubt on the leading theory of what causes ice ages around the world — changes in the way the Earth orbits the sun. The researchers found that glacier movement in the Southern Hemisphere is influenced primarily by sea surface temperature and atmospheric carbon dioxide rather than…

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For more than 250 million years, four-limbed land animals known as tetrapods have repeatedly conquered the Earth’s oceans. These creatures–such as plesiosaurs, penguins and sea turtles–descended from separate groups of terrestrial vertebrates that convergently evolved to thrive in aquatic…