Why Dinosaurs Turned into Birds
Most scientists now believe that, due to the fossil evidence, birds are an evolutionary offspring of dinosaurs. Now they’ve discovered that 175 to 275 million years ago, when this evolution began to take place, oxygen fell to dangerously low levels on Earth. This may have led to the major extinction event which eliminated 90% of all the species. It would have made breathing the air at sea level the same as breathing at high altitudes today and could have led to the development of the unusual breathing system found in some dinosaurs, including the brontosaurus, which still exists in today’s birds.
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