Winged dinosaurs were 'too heavy to fly'



At the cinema, they swoop through the air and circle ominously overhead with their razor-sharp bills.



But in fact, the flying dinosaurs which feature in King Kong and Jurassic Park would have struggled to get off the ground, researchers believe.



After analysing the flight of 28 birds, scientists from Tokyo University say the pterodactyl, which weighed a quarter of a ton, would not have been able to flap its wings fast enough to stay in the air - and could only glide relatively short distances from clifftops.

Myth? Many believed that pterodactyls were the largest animals to ever have flown, but an expert now says they were simply too heavy

But fossil experts say their skeletons did evolve for full flight.



Pterodactyls appeared about 251million years ago and were still thriving when the dinosaurs became extinct 65million years ago.



Technically they are not dinosaurs, but prehistoric winged reptiles.



Professor Katsufumi Sato of Tokyo University 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 40kg (88lb) cannot flap their wings fast enough to stay in the air.



This would explain why the wandering albatross weighs only 22kg (49lb).

Flight of fancy? Researchers say the pterodactyl, as seen here in Jurassic Park III, would not have been able to flap its wings fast enough to stay in the air



A bird weighing almost 40kg '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.



He calculated that the largest animal capable of soaring flight could not have weighed more than a Labrador dog.



But his conclusions have not endeared him to pterodactyl experts, who believe the animals were dynamic soarers.



Dr Mike Habib, of Johns Hopkins Medical School in Baltimore, Maryland, said: 'His 40kgs threshold is problematic.'

He added that although some pterosaurs were four times heavier than the wandering albatross, differences in anatomy, physiology and environment all had to be taken into account.