London: Ostriches became fat and gave
up flying after dinosaurs died out and were no longer around
to chase them, a new study has suggested.
Palaeontologists have claimed that an abundance of
food and lack of predators following the mass extinction 65
million years saw previously flighted birds put on so much
weight that they had to walk instead.
In fact, their molecular dating study revealed that
the African ostrich, Australasian emu, South American rhea and
New Zealand moa became flightless independently following the
disappearance of dinosaurs, 'The Daily Telegraph' reported.
Dr Matthew Phillips of Australian National University,
who led an international team, said the discovery, which came
after a study of the birds' genes, was surprising because it was
previously thought they're descended from non-flying ancestors.
"Many of the world's largest flightless birds, known
as ratites, were thought to have shared a common flightless
ancestor. Our study suggests that the flighted ancestors of
ratites appear to have been groundfeeding 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," Dr Phillips was
quoted as saying.
The findings are published in the 'Systemic Biology'
journal.
PTI
First Published: Saturday, January 23, 2010, 15:06