January 5, 2011
Ancient Bird Used Its Wings As Weapons
Scientists suggest that an extinct flightless bird from Jamaica fought rivals and predators using wings which evolved into clubs.
The boney bludgeons the bird carried are unlike anything else known in the bird world.
The scientists report finding bones that had apparently been broken by another bird's club.
The species may have survived until less than 10,000 years ago.
The bird was probably about the size of a chicken, but with an infinitely more robust armory.
Fossils show that the metacarpus was elongated and much bigger than in related species, with very thick walls.
The researchers wrote that this allowed the wings to function "in combat as a jointed club or flail."
"We don't really know how they would have used these clubs, but we do know that modern ibises grab each other by the beak and pound away with their wings," said Nicholas Longrich, from Yale University in the US.
"And we analyzed two bones that had been broken during fighting, including a humerus (upper arm bone) that had been snapped in half - it had started to re-heal, although the two ends hadn't knitted together," he told BBC News.
Storris Olson from the Smithsonian Institution, who was also involved in the research, was one of the scientists who first identified Xenicibis xympithecus back in the 1970s.
A number of other birds are known to fight by hitting each other with their wings.
Some have evolved spurs to increase the damage they can wreak.
The extinct solitairy bird from the Indian Ocean island of Rodrigues had bony growths colloquially known as "musketballs" on their wings, which appear to have served the same purpose.
"But among vertebrates - there's no animal of any sort that has anything like a limb modified as a club," Longrich told BBC.
Julian Hume, an avian paleontologist with London's Natural History Museum, told BBC that unlike most flightless birds, Xenicibis retained long wings, possibly making its flailing more powerful.
"Ibis young stay in the nest for a relatively long time," he said.
"So if they retained that feature, that suggests they needed it for defense against predators - and there were quite a few on Jamaica."
However, ibises also are more territorial, so the flailing clubs may also have found employment in disputes between individuals, probably with both sexes involved.
The findings are reported in the Proceedings of the Royal Society B.
Image 1: The prehistoric Xenicibis used its wings like two clubs hinged at the wrist joint in order to swing at and attack one another. Credit: Nicholas Longrich/Yale University
Image 2: Researchers reconstructed the skeleton of Xenicibis based on partial fossil skeletons found in Jamaica. Credit: Nicholas Longrich/Yale University
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