There’s a new champion in the featherweight boxing division. According to a new study, paleontologists have discovered that an extinct flightless bird from Jamaica swung its unusually thick, club-like wingtips to fend off predators and rivals from its own species alike. The bird, a type of ibis known as Xenicibis, lived on the Caribbean island until about 12,000 years ago. In 1995, a team of paleontologists looking for remains of an extinct giant rodent chanced across a collection of Xenicibis fossils exquisitely preserved in one of the hundreds of limestone caves that dot Jamaica’s terrain. The nearly complete skeletons revealed a chicken-sized bird with thin upper-arm bones that curved and thickened greatly toward their wingtips. Yale University paleontologist Nicholas Longrich, lead author of the study which appeared last week in the Proceedings of the Royal Society B, didn’t know what to make of the unusual wing shape.
“It was bizarre,” he said. “No one had seen anything like it. … No other bird has or had anything remotely similar.”
Longrich’s colleague and co-author of the paper, Storrs Olson at the Smithsonian National Museum of Natural History, first suggested that perhaps Xenicibis walked on its wingtips as if they were forelegs, but the researchers discounted that idea after measuring the wings and determining they weren’t long enough for walking on.
Longrich next considered fighting. Other birds are known to use their wings to punch each other, and some have even evolved wing spikes to aid them in these fights. Since Xenicibis was flightless, the researchers reasoned, the evolution of its wing shape wasn’t constrained like that of flying birds. That would have freed the ibises’ wings to evolve fully into weapons, Longrich said.
Two of the wing bones they looked at were fractured and broken, indicating they had been involved in fairly heavy combat. The wounds are a testament to the force Xenicibis could put behind its blows, Longrich said.
“There was a lot of muscle behind those wings,” he said. “It was a well-designed weapon.”
Modern ibises are very territorial, he said, as are many other birds that use their wings to fight each other. Xenicibis, too, likely wielded its wings to compete with rivals over nesting and feeding grounds, Longrich said, as well as protect their nests and offspring from predators.
Helen James, curator of birds at the National Museum of Natural History and uninvolved with the study, said she was astonished by how Xenicibis’ wings, unfettered by flight, were able to take such a peculiar evolutionary turn.
“It doesn’t really have a parallel,” she said.
Richard Prum, an ornithologist at Yale University who also wasn’t involved with the study, was likewise surprised and impressed.
“It’s definitely an unexpected result,” he said. “But that’s the interesting thing about biodiversity. There are lots of interesting ways for animals to accomplish their goals.”
Xenicibis,prehistoric bird,Jamaica
