Science News Roundup: Scientists reveal origin of mammal evolution milestone: warm-bloodedness

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Scientists reveal origin of mammal evolution milestone: warm-bloodedness

Scientists have answered a longstanding question about mammalian evolution, examining ear anatomy of living and extinct mammals and their close relatives to determine when warm-bloodedness - a trait integral to the lineage's success - first emerged. Researchers said on Wednesday that the reduced size of inner ear structures called semicircular canals - small, fluid-filled tubes that help in keeping balance - in fossils of mammal forerunners showed that warm-bloodedness, called endothermy, arose roughly 233 million years ago during the Triassic Period.