The location of the finds is unexpected, because today the birds are only known from the Americas.

In the latest edition of Science magazine, Dr Gerald Mayr claims the fossils show many striking resemblances to modern hummingbird groups.

Other fossil hummingbirds have been found in Central America, Europe and Asia, but they are either very different from modern ones or are known from just a few bones.

The new fossils, which have been assigned to the species Eurotrochilus inexpectatus, were endowed with long, nectar-sucking beaks and wings designed for feeding while hovering.

They share key anatomical features on their wings with modern hummingbirds. The primitive hummingbird Jungornis tesselatus lacks these features.

This suggests that Eurotrochilus and modern hummingbirds belong together in a distinct group of birds, while Jungornis belongs to another, more primitive group.

Professor Ethan Temeles, of Amherst College in Massachusetts, US, speculated that the extinction could have been caused by climate change.