GAINESVILLE, Fla., Sept. 8 (UPI) -- U.S. scientists say flightless birds known as ratites, such as Australian emus, don't share a common ancestor as once believed.
Instead, large flightless bird species of the southern continents individually lost flight ability after diverging from ancestors that could fly, said University of Florida Professor Edward Braun.
The finding, which appeared in last week's online edition of the Proceedings of the National Academy of Sciences, has several implications.
First, it means birds, like the emus, are more closely related to their airborne cousins than to other ratites, Braun said. Second, it means ratites are products of parallel evolution -- different species in different environments following the same evolutionary course.
Previously, ratites were used as examples of vicariance -- the geographical division of a species, resulting in two or more similar sub-groups that undergo further evolutionary change, becoming very distinct from one another.
The new research, said Braun, makes it more likely the ratites' ancestors distributed themselves after the breakup of Gondwana, about 167 million years ago, in a much more obvious way: They flew.
The study also involved scientists from the Smithsonian Institution, the Field Museum of Natural History, Wayne State University and Louisiana State University.
