Having two sets of teeth during lifetime—a baby set that falls out and an adult set that replaces it.
From Greek di- (two) + phyo (grow) + odontos (tooth). Most mammals, including humans, are diphyodont. The term was formalized in comparative anatomy in the 19th century.
You're literally diphyodont yourself—your baby teeth and permanent teeth are named with this fancy Greek term, meaning scientists considered two-toothed animals special enough to name!
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