In an evolutionary novelty, a flightless prehistoric bird found only in Jamaica used its weighty wing bones to clobber rivals during territorial disputes. Researchers examined several partial skeletons of Xenicibis xympithecus, an extinct wading bird about the size of a large chicken that lived some 10,000 years ago. The bone at the tip of the birds' wings—the "hand" bone—was so thick and curved, it appeared deformed. Xenicibis used its hefty hand bones for battle, swinging them like clubs, the researchers posit. Indeed, two of the fossils—a hand bone and upper arm bone—showed wear and tear consistent with fighting. Other birds use their wings as weapons, too, but none wield their hand bones like clubs. The most likely targets of these powerful swings, the researchers report online today in the Proceedings of the Royal Society B, were other Xenicibis, although the bird may have also used its clublike wings to protect its eggs and young from predators.