アメリカ自然史博物館のインスタグラム(amnh) - 11月17日 13時34分

As a general rule, antlers in the deer family are an extension of an animal's skull and shed each year. Horns, on the other hand, have a bone interior and an outer sheath of keratin (which also makes up our hair and fingernails). Horns also typically grow for an animal's entire life. An exception to this rule? The North America’s pronghorn, which sheds its horn sheath each year. Pronghorn are the sole surviving member of the family Antilocapridae—and are more closely related to giraffes and okapi than to antelope.
Photo: Nature's Pics Online

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