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January 18, 2011

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Ancient bird used club-like wings as weapon, researchers claim

Jan. 4, 2011
Courtesy of Yale University
and World Science staff

Long be­fore me­di­e­val knights wielded flails or mar­tial artists bran­dished nun­chucks, a flight­less bird may have used its own wings as a si­m­i­lar type of weap­on.

Pa­le­on­tol­ogists say Xeni­ci­bis, a bird that lived about 10,000 years ago on the is­land of Ja­mai­ca, probably used its spe­cial­ized wings like a flail, swing­ing its up­per arm and strik­ing its en­e­mies with its thick hand bones.

A diagram of the re­con­structed ske­le­ton of Xe­ni­ci­bis based on part­ial fos­sil ske­le­tons found in Ja­mai­ca. (Cour­te­sy Nich­olas Lon­grich/Yale U.)

“No an­i­mal has ev­er evolved an­y­thing quite like this,” said Nich­o­las Lon­grich of Yale Uni­vers­ity, who led the re­search. “We don’t know of any oth­er spe­cies that uses its body like a flail. It’s the most spe­cial­ized weap­onry of any bird I’ve ev­er seen.”

A flail is a wea­pon con­sist­ing of a stick with a heavy ob­ject, such as a spiked iron ball, that swings from its end by a chain.

Lon­grich and col­leagues an­a­lyzed some re­cently dis­cov­ered par­tial skele­tons of Xeni­ci­bis and found the wings were un­like an­y­thing they’d seen. At first “I as­sumed it was some sort of de­form­ity,” Lon­grich said. “No one could be­lieve it was ac­tu­ally that bizarre.”

The bird, the size of a large chick­en, is an­a­tom­ic­ally much like oth­er mem­bers of the ibis fam­i­ly, to which it be­longs—large wad­ing birds with long, down-curved bills and long legs. The main dif­fer­ence an­a­tom­ic­ally is in its wings, re­search­ers said, which in­clude thick, curved hand bones un­like those of any oth­er known bird. Xeni­ci­bis al­so had a much larg­er breast­bone and long­er wings than most flight­less birds. “That was our first clue that the wings were still be­ing used for some­thing,” Lon­grich said.

Xeni­cibis used its wings like two clubs hinged at the wrist joint to swing at and at­tack each oth­er, sci­en­tists say. (Cour­te­sy Nich­olas Lon­grich/Yale U.)

While some oth­er birds punch or ham­mer each oth­er with their wings, re­search­ers ex­plained, Xeni­ci­bis is the only known an­i­mal to have used its hands, hinged at the wrist joint, like two base­ball bats to swing at its op­po­nents. Al­though mod­ern day ibises don’t act this way, they are very ter­ri­to­rial, with mates of­ten fight­ing oth­er pairs over nest­ing and feed­ing rights.

Xeni­ci­bis might have al­so used its wings to fend off oth­er spe­cies that preyed on its eggs or young, the sci­en­tists added. Xeni­ci­bis is con­sid­ered un­usu­al in that it be­came flight­less even in the midst of many preda­tors, in­clud­ing the Ja­mai­can yel­low boa, a small ex­tinct mon­key and over a doz­en birds of prey.

The investigators found that two of the wing bones in the col­lec­tion showed ev­i­dence of com­bat, in­clud­ing a frac­tured hand bone and a centimeter-thick up­per arm bone that was bro­ken in half. The dam­age is proof of the ex­treme force the birds could wield with their spe­cial­ized wings, Lon­grich said.

Lon­grich and col­leagues re­ported their find­ings in the re­search jour­nal Pro­ceed­ings of the Roy­al So­ci­e­ty B.

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Long before medieval knights wielded flails or martial artists brandished nunchucks, seems a flightless prehistoric bird used its own wings as a similar type of weapon, a study has found. Paleontologists say Xenicibis, a bird that lived about 10,000 years ago and only in Jamaica, probably used its specialized wings like a flail, swinging its upper arm and striking its enemies with its thick hand bones. “No animal has ever evolved anything quite like this,” said Nicholas Longrich of Yale University, who led the research. “We don’t know of any other species that uses its body like a flail. It’s the most specialized weaponry of any bird I’ve ever seen.” Longrich and colleagues have analyzed some recently discovered partial skeletons of Xenicibis and found the wings were unlike anything they’d seen. At first “I assumed it was some sort of deformity,” Longrich said. “No one could believe it was actually that bizarre.” The bird, the size of a large chicken, is anatomically much like other members of the ibis family, to which it belongs—large wading birds with long, down-curved bills and long legs. The main difference anatomically is in its wings, researchers said, which include thick, curved hand bones unlike those of any other known bird. Xenicibis also had a much larger breastbone and longer wings than most flightless birds. “That was our first clue that the wings were still being used for something,” Longrich said. While some other birds punch or hammer each other with their wings, researchers explained, Xenicibis is the only known animal to have used its hands, hinged at the wrist joint, like two baseball bats to swing at its opponents. Although modern day ibises don’t act this way, they are very territorial, with mates often fighting other pairs over nesting and feeding rights. The birds may have also used their wings to fend off other species that might have preyed on the birds’ eggs or young, the scientists added. Xenicibis is considered unusual in that it became flightless even in the midst of a number of predators, including the Jamaican yellow boa, a small extinct monkey and over a dozen birds of prey. The team found that two of the wing bones in the collection showed evidence of combat, including a fractured hand bone and a centimeter-thick upper arm bone that was broken in half. The damage is proof of the extreme force the birds could wield with their specialized wings, Longrich said. Longrich and colleagues reported their findings in the research journal Proceedings of the Royal Society B.