Countries demand their fossils back, forcing natural history museums to confront their past

Step into the main hall of the Natural History Museum here and you'll be greeted by a towering dinosaur skeleton, the tallest ever mounted. Nearly four stories high and twice as long as a school bus, the sauropod Giraffatitan brancai was the largest dinosaur known for more than a half-century. It has been a crowd magnet since it was first displayed in 1937.

But the tidal flats Giraffatitan bestrode 150 million years ago weren't in Europe. It lived in eastern Africa, today's Tanzania, much of which was a German colony when the fossil was unearthed in the early 1900s. Now, some Tanzanian politicians argue the fossils should return to Africa.

Berlin's Natural History Museum isn't the only one facing calls for the return of fossils, which echo repatriation demands for human remains and cultural artifacts. Many specimens were collected under conditions considered unethical today, such as brutal colonial rule that ignored the ownership rights and knowledge of indigenous people. "Natural history museums as we know them wouldn't exist without the colonial period," says Holger Stoecker, an African studies expert at Humboldt University here. He says repatriation requests are prompting new questions about the stories of "discovery" that many museums have traditionally told. The discussion "is escalating right now," and highlights that natural history isn't "apolitical and neutral," says Ciraj Rassool, a historian and museum studies expert at the University of the Western Cape in Cape Town, South Africa.