Ancestor of emu and cassowary lost flight after becoming fat and lazy
January 26th, 2010 - 4:26 pm ICT by ANISydney, January 26 (ANI): A new study has suggested that the flighted ancestor of birds such as the Australian emu and cassowary became too heavy to fly after the extinction of dinosaurs made it safer to forage for food.
According to a report by ABC News, the finding by Australian National University (ANU) biologist Dr Matthew Phillips and colleagues at Massey University in New Zealand, follows on from recent work that raised uncertainty about the “single ancestor” theory of the group of flightless birds, known as ratites.
Ratites are a group of flightless birds that include the Australian emu and cassowary, African ostrich, New Zealand’s kiwi and now-extinct moa, rhea from South America and the extinct elephant birds of Madagascar.
The study used molecular dating of the mitochondrial DNA from the moa, which stood 2.5 metres tall and weighed up to 250 kilograms, and found its closest relative to be the tinamous - a flighted bird the size of quail, found in South America.
Previously, it was thought ratites all shared a common flightless ancestor about 80 million years ago and their worldwide dispersal occurred before the supercontinent of Gondwanaland broke up.
But, according to Phillips, the problem with this theory was that much of the continental break-up occurred well before the proposed common ancestor.
The study, which also included DNA sequencing of 22 bird species including flightless and flighted birds, shows ratites became flightless around 65 million years ago.
This coincides with the extinction of dinosaurs in the Cretaceous-Tertiary event.
“Our study suggests that the flighted ancestors of ratites appear to have been ground-feeding birds that ran well,” said Phillips.
“In the absence of predators and with abundant food resources on the ground, there is a tendency for birds to evolve larger size and become flightless,” he added.
“Larger ground-feeding birds can be more efficient at turning food into growth and reproduction, but with size increase, comes the cost of flight becoming less efficient,” he said. (ANI)
- Eggshells reveal birds' evolutionary secrets - Jan 04, 2012
- Some non-avian feathered dinos may have been flightless birds - Jan 10, 2010
- Scientists extract DNA of extinct giant bird from fossil eggs - Mar 10, 2010
- Long-held assumptions of flightless bird evolution challenged - Sep 04, 2008
- Dinosaurs may have descended from birds, not the other way around - Feb 10, 2010
- Birds inherited sense of smell from dinos: Study - Apr 13, 2011
- Dinosaurs probably had lice: Study - Apr 06, 2011
- DNA from extinct Moa bird rewrites New Zealand's geological history - Nov 22, 2009
- Brains of birds have a dinosaur source: Study - Apr 13, 2011
- Dinos' evolving beaks were like 'Swiss Army knives' - Dec 21, 2010
- Man cooked food on fire far earlier than originally thought - Aug 23, 2011
- How giant dinos soared the high skies - Nov 15, 2010
- Birds in the dino era pecked just like their modern counterparts - Oct 27, 2010
- Extinct Jamaican bird clobbered rivals with club-like wings - Dec 29, 2010
- 'Giant flea fed on dinosaur blood like mosquitoes' - May 02, 2012
Tags: 65 million years, abc news, abundant food, african ostrich, australian emu, birds of madagascar, cassowary, common ancestor, dna sequencing, elephant birds, extinct elephant, extinction of dinosaurs, flightless birds, food resources, massey university, matthew phillips, mitochondrial dna, ratites, supercontinent, university in new zealand