A lioness known as Nosikitok, wearing a tracking collar from a conservation group, nurses a young leopard cub in what experts say is a never-before-seen occurrence between different cat species.

Striking new photos from Tanzania showing a wild lioness nursing a leopard cub document such an occurrence for first time, according to big cat experts.

“It’s unprecedented,” Luke Hunter, president and chief conservation officer of wild cat conservation group Panthera, told National Geographic. “We never see this in the wild.”

Although experts have documented big cats “adopting” orphaned cubs of the same species, Hunter said in a Panthera news release that he knows “of no other example of inter-species adoption or nursing like this among big cats in the wild.”

The mother pictured is a 5-year-old lioness named Nosikitok, living in Tanzania’s Ngorongoro Conservation Area, while the leopard cub is estimated to be just a few weeks old. Panthera released the photos after a visitor to the area snapped them and sent them to the nonprofit.

A closeup of Nosikitok and the cub.

It’s not clear how Nosikitok and leopard, whose mother has not be seen, got together.

The lioness recently had cubs of her own, but she may have lost them somehow, Ingela Jansson of KopeLion ―…