Sifrhippus was a species of horse about the size of an average duck and roamed North America 56 million years ago.
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Dolphins sometimes have fun by blowing bubbles and creating rings of air underwater, which they then swim through.
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A 42-foot sperm whale has about 7 tons of oil in it.
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Alligator snapping turtles can live for over 150 years. Scientists know this because some of the turtles had musket balls in their stomachs.
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A hippo sleeping underwater automatically rises to the surface every ~4 minutes and breathes without waking.
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