Emus. New research suggests that ancestors of the African ostrich, Australasian emu plus cassowary, South American rheas and New Zealand moa became flightless independently, in close association with the extinction of the dinosaurs about 65 million years ago. (Credit: iStockphoto/John Carnemolla)
Dinosaur Extinction Grounded Ancient Birds, New Research Finds
ScienceDaily (Jan. 26, 2010) — 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
The study, led by Dr Matthew Phillips, an ARC Postdoctoral Fellow at the ANU Research School of Biology, looked at the
Their molecular dating study suggests that the ancestors of the African ostrich, Australasian emu plus cassowary, South American rheas and
"Many of the world's largest flightless birds, known as ratites, were thought to have shared a common flightless ancestor. We followed up on recent uncertainty surrounding this assumption," said Dr Phillips.
"Our study suggests that the flighted ancestors of ratites appear to have been ground-feeding birds that ran well. So the extinction of the dinosaurs likely lifted predation pressures that had previously selected for flight and its necessary constraint, small size. Lifting of this pressure and more abundant foraging opportunities would then have selected for larger size and consequent loss of flight."
The finding of independent origins of flightlessness also solves a mystery of how these flightless birds dispersed across the world over marine barriers -- their ancestors flew. "Ratite birds have been thought of as relics of the former Gondwanan supercontinent, which combined
The researchers' paper is published in this month's issue of the journal Systematic Biology.
Adapted from materials provided by Australian National University.
- Phillips et al. Tinamous and Moa Flock Together: Mitochondrial Genome
Sequence AnalysisReveals Independent Losses of Flight among Ratites. Systematic Biology, 2010; 59 (1): 90 DOI: 10.1093/sysbio/syp079
Australian National University. "Dinosaur Extinction Grounded Ancient Birds, New Research Finds." ScienceDaily 26 January 2010. 27 January 2010 <http://www.sciencedaily.com /releases/2010/01/100126105429.htm>.