Modern birds capable of flight all have a specialized wing structure called the propatagium without which they could not fly. The evolutionary origin of this structure has remained a mystery, but new research suggests it evolved in nonavian dinosaurs. The finding comes from statistical analyses of arm joints preserved in fossils and helps fill some gaps in knowledge about the origin of bird flight.-
[sciencedaily.com]
I find it fascinating how some species of birds have evolved without the necessity to fly due to lack of predators.I took this photo when I visited a small island of the Seychelles archipelago of a species (white tailed tropic bird) that makes its nests on the ground due to also not being threatened by any predators.