A flightless ibis (Xenicibis xympithecus) that lived on Jamaica until about 10,000 years ago had wings that evolved into weapons. It would use its club-like wings to beat predators and perhaps other ibis in defense of its territory and young. However, these club-like wings proved useless when humans finally showed up and the birds were extinct shortly afterwards.
“Working with Olson, Longrich went to Jamaica and found more fossils – including curved hefty handbones.
He thought the first he found was a deformity, but as he found others, including a couple that had been cracked and healed, he realized they had been used as clubs. The new fossils also showed the wrists were hinged so the hands could swing like flails.
“I would guess that they would try to grab each other using the beak and then just proceed to pound each other using the wings,” Longrich told Discovery News.”