The carved surface of an ostrich egg shows what is thought to be the oldest known depiction of the New World on a globe, a U.S. map society says.

The globe, dated to around 1500, was bought anonymously by a private institution in London in 2012 and then lent to independent researcher Stefaan Missinne, who has reported his analysis in The Portolan, the journal of the Washington Map Society.

The egg globe shows North America as a number of unnamed scattered islands, while regions of South America are labeled Mundus Novus or "New World," Terra de Brazil and Terra Sanctae Crucis, "Land of the Holy Cross."

Ships, sea monsters, ocean waves, a shipwrecked sailor, place names and the sentence "HIC SVNT DRACONES" -- "here be dragons" -- have been carved into the surface of the giant egg.

The globe is thought to be older than the Hunt-Lenox globe in the collection of the New York Public Library, one of the earliest surviving map globes from the period immediately following the Europeans' discovery of the New World.

It is thought to have been created around 1510.