The "rediscovery" of a stunningly-preserved 30 million-year-old hummingbird fossil in southern France has deepened the mystery of why these fragile creatures disappeared from Europe and now exist only on the American continent.
The fossil was originally found by an amateur palaeontologist at the end of the 1980s in the Lubron national park in Provence. It then lay in his private collection for a number of years, unknown to the wider world and as good as undiscovered.
It was finally "re-discovered" after its purchase by another amateur palaeontologist, Nicolas Tourment, a long-time colleague of Antoine Louchart who is an expert on bird fossils.
M. Louchart, the principal author of a study of the fossil recently published online in the German journal Naturwissenschaften and who has worked on excavations all over Europe and in Africa, spotted the fossil in his colleague's collection. He recognised it as one of only two 30 million-year-old hummingbird fossils ever to be found and by far the most complete.
The fossil is extraordinary in several ways: it has been exceptionally well preserved; its tiny vertebrae, delicate feet, the bones of its wings, its skull and beak are all intact. Even its feathers have left a fine layer of black powder around it. Also astonishing is that apart from a few very small differences, this ancient hummingbird is very similar to its modern relatives.
Various characteristic features can be easily identified on the fossil, such as a v-shaped bone in the lower part of the beak which permits the bird to retract the long tongue it uses for sucking nectar from flowers.
Also visible are the specialist structures on the wings that permit hummingbirds to flap their wings in any direction. This allows them to hover in mid-air while sucking nectar, with some species' wings flapping up to 70 times per second. They are also the only bird group able to fly backwards.
In 2004 another hummingbird fossil was excavated in Germany and seemed to pre-date anything ever found in the Americas. However, this discovery was surrounded by scepticism as only the back part of it had been preserved and in a very poor condition and therefore made identification difficult. At the time, experts doubted that the oldest fossil hummingbird ever discovered would have been found in Europe given they now only live across the Atlantic. The French fossil has allayed these doubts.
But the oldest specimen found in the Americas is a mere 1.8 million years old. This has left a baffling 20-million-year gap in the fossil record, re-igniting the question of when and why these birds abandoned Europe for the New World.
"The palaeontological gap in America is for the moment inexplicable," said M. Louchart. "One idea which has been suggested is that there are not the right geological conditions in America for preservation, especially given the smallness and delicacy of hummingbirds."
In the Lubron national park in France, which 30 million years ago was an immense tropical lagoon, experts and amateurs are continuing to excavate, but according to M. Louchart the birds are "very, very rare: sometimes you might find a feather". The small number of other bird fossils which have been discovered there, all in an equally remarkable condition as the hummingbird, include a cormorant, an ibis, a crane, and a cuckoo.
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