A new study of extinct and living flightless birds (ratite) has produced a new story of the evolution of flightless birds. Kieren J. Mitchell from the University of Adelaide in Australia and an international group of colleagues have shown DNA evidence that disproves present thought about the origin of flightless birds.
Previously the evolution of flightless birds was thought to have originated from a common ancestor. The drifting of continents from the original super-continents was thought to have provided different habitats that produced the variety of flightless birds like the moa in Australia, the ostrich in Africa, and the extinct elephant bird. The new study indicates that no common ancestor of flightless birds was involved that was flightless.
An analysis of the mitochondrial DNA of the elephant bird and a comparison to the DNA of other flightless birds indicates that the elephant bird is more closely related to the kiwi than any other species of flightless birds. The elephant bird is strictly a herbivore and the kiwi is an omnivore. The ostrich shows very little genetic relationship to either species but may be the oldest flightless bird.
The researchers conclude that all extinct and living species of flightless birds developed from ancestors that could originally fly. The dispersal of the species across the wide range of continents was produced by flight not continental drift. The most probable reason that flying birds became flightless is the lack of mammal predators. This conclusion indicates that evolution of flightless birds began during periods of mammal extinction.
Flightless birds developed from flying birds. The dispersal of flying birds that adapted to being flightless began as long as 73 million years ago and may not have ended until four million years ago. This discovery is considered to be a biological, paleontological, and evolutionary proof that is unprecedented.
