The fossils showed that the legs of the Aldabra rail were heavier and more robust than the legs of the white-throated rail, indicating that the birds on the atoll were losing the ability to fly.
The lack of predators on the island did not make flight a necessary trait for survival. As flightless birds, the Aldabra rail lays their eggs on the ground and has strong legs to run around on straight after hatching. This is the first time that iterative evolution has been documented in rails.
“There is no other case that I can find of this happening where you have a record of the same species of bird becoming flightless twice,” said Dr. Julian Hume, a paleontologist at the Natural History Museum in London.
“It wasn’t as if it were two different species colonizing and becoming flightless. This was the very same ancestral bird.”
