The secretive indri (Indri indri) of Madagascar, the largest living lemur. It is also critically endangered and highly evolutionarily distinct with no close relatives, which makes its branch one of most precarious on the mammal evolutionary tree. In the likely event that the indri goes extinct, we will lose 19m years of unique evolutionary history from the mammal tree of life. (Photo by Pierre-Yves Babelon/Aarhus University)

A train attendant helps a passenger to adjust her seat at the business class carriage on a CRH 380A bullet train Thursday, June 16, 2011. (Photo by Reuters/China Daily)

English model Cara Delevingne attends The Metropolitan Museum of Art's Costume Institute benefit gala celebrating the opening of the “In America: An Anthology of Fashion” exhibition on Monday, May 2, 2022, in New York. (Photo by Evan Agostini/Invision/AP Photo)

Monks take a tiger out of its cage for an afternoon walk June 5, 2001 at the Wat Pa Luangta Bua monastery in Kanchanaburi, Thailand. (Photo by Paula Bronstein/Getty Images)

A craftsman works on making human anatomy mannequins on April 23, 2014 in Depok, West Java, Indonesia. The mannequins are made from fiberglass and will be used in schools, hospitals and laboratories. (Photo by Nurcholis Anhari Lubis/Getty Images)

Dried and shrivelled corpses, some fully clothed and some in coffins, line the wall of a vault of the Pantheon Cemetery on the summit of Cerro del Trozado in Mexico. They were removed from the crypts because of non-payment of cemetery fees. The hot dry air stopped the bodies from rotting. Most of them were placed here between the turn of the century and WW I. (Photo by Three Lions/Getty Images). Circa 1955

An employee at Christie's auction house examines a complete sub-fossilised elephant bird egg on March 27, 2013 in London, England. The elephant bird egg is expected to fetch 30,000 GBP when it features in Christie's “Travel, Science and Natural History” sale, which is to be held on April 24, 2013 in London. (Photo by Oli Scarff)

Victoria's Secret Angel Martha Hunt celebrates the 2015 What Is s*xy? List in San Diego on September 26, 2015 in San Diego, California. (Photo by Joe Scarnici/Getty Images for Victoria's Secret)