An abundance of food and lack of predators following the extinction of dinosaurs saw previously flighted birds fatten up and become flightless, according to new research from The Australian National University.

The study, led by Dr Matthew Phillips, an ARC Postdoctoral Fellow at the ANU Research School of Biology, looked at the mitochondrial genome sequences of the now-extinct giant moa birds of New Zealand. To their surprise, the researchers found that rather than having a flightless relative, their closest relatives are the small flying tinamous of South America.

http://news.anu.edu.au/?p=1889