The okapi became known to European explorers in the late 19th century, and then several explorers tried and failed to even see a live okapi. Sir Harry Hamilton Johnston often gets credit for its discovery, but there's much more to the story than that. 

Research:

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• “A MOST CURIOUS ANIMAL, A CULTURAL SYMBOL, A SPECIES ON THE BRINK.” Okapi Conservation Project. https://www.okapiconservation.org/the-okapi/
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• Brzezinski, Bartosz. “Of okapis and men: Antwerp Zoo helps preserve endangered species.” Flanders Today. Aug. 14, 2016. https://web.archive.org/web/20160814194411/http://www.flanderstoday.eu/living/okapis-and-men-antwerp-zoo-helps-preserve-endangered-species
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