Pterosaurs 'flightless' theory
Updated on 02 October 2008
Pterosaurs were not the awesome flying dragons of popular belief, it has been claimed.
In fact, the largest of them may never have got off the ground, according to one expert.
The biggest of the reptiles, which lived at the time of the dinosaurs, had wingspans of 15 metres (49ft) and weighed almost a quarter of a tonne.
They are often depicted in movies such as Jurassic Park soaring across the sky and swooping down on prey.
But in reality, says Dr Katsufumi Sato from the University of Tokyo, they would have been too heavy to fly.
Dr Sato studied large species of birds in the Crozet Islands, between Madagascar and Antarctica, including the world's biggest, the wandering albatross.
By attaching accelerometers - devices that measure acceleration and G-force - to the wings of 28 birds, he determined that animals weighing more than 40kgs (88lbs) cannot flap their wings fast enough to stay in the air.
This would explain why the wandering albatross weighs only 22kgs (49lbs). A bird weighing almost 40kgs "would not have a safety margin to fly in bad weather," Dr Sato told New Scientist magazine.
The maximum speed a bird can flap is limited by its muscle strength and decreases for heavier species with longer wings.
Dr Sato presented his findings at the Third Annual Biologging Science Symposium at Stanford University in California.
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