A pair of 30 million-year-old fossils from southern Germany are the oldest fossil hummingbirds, a researcher says.
The fossils are strikingly similar to modern hummingbirds
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.
The extinct hummingbirds may have influenced the shape of some modern Asian and African flowers.
"Fossils of primitive hummingbirds have been found in the Old World before, but it was a great surprise to find a bird that looked so similar to the modern hummingbirds of the Old World," Dr Mayr, of the Senkenberg Natural History Museum in Frankfurt, told BBC News Online.
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.
"Maybe hummingbirds used to have a much wider distribution but, for some reason, they went extinct in the Old World," said Dr Mayr.
Dr Mayr said he had no idea what caused this extinction.
Professor Ethan Temeles, of Amherst College in Massachusetts, US, speculated that the extinction could have been caused by climate change.
"Certainly if you consider the small size of hummingbirds, if there were climatic changes, that might have been the factor responsible," he told BBC News Online.
Extinct hummingbirds may have influenced the shape of some plants
"If you look at temperate, migratory hummingbirds that are coming up to, for example, Canada - if you end up having a snowstorm early in the year or late in the year, it can kill the population."
But Professor Temeles said that competition between hummingbirds and other nectar-feeding birds might also have been a factor.
Extinct hummingbirds might also have helped determine the shape of some modern Asian and African flowers through a back-and-forth evolutionary process called co-evolution.
These plants may include the species Canarina eminii, Impatiens sakeriana and Agapetes.
"If you take one of the North American species of Impatiens, it has a very long floral tube that's shaped like a trumpet, ending in a nectar tube or spur.
"The nectar-containing spur associates with the hummingbird beak to some extent - though not perfectly. At the same time, they contain petals around the flower which suggests they provide a landing platform for bees."
Dr Mayr added: "Botanists now have to look at plants in the Old World to see if any of them show evidence of co-evolving with hummingbirds."