Giving a Big Bird a Lift

Some 100 million years ago, when huge dinosaurs still trod the earth, the skies were dominated by a creature equally awesome: the fish-eating Pteranodon. Endowed with a wingspread of 25 ft.* but extremely short, weak legs, the bizarre reptile clearly had to fly to spot and capture its prey. Yet the construction of its wings (unsuitable for continuous flapping) and its large size have long seemed to zoologists almost insurmountable obstacles to flight. "How this animal could get itself into the air from level ground," wrote Harvard Paleontologist Alfred Romer, "is difficult to understand."

Scientists have somewhat lamely avoided the question by suggesting that Pteranodon plunged off high cliffs in order to build up sufficient air speed for its gliding flight. But if it could not regain altitude in flight, how did it climb back to the cliff top again on its woefully inadequate legs? And how did it take off from the water after fishing?

These perplexing questions may now have been answered by two scientists using a standard aerodynamic formula. Assuming that Pteranodon weighed only 40 Ibs. (it had an extremely delicate skeleton), Geologist Cherrie D. Bramwell and Physicist G.R. Whitfield of the University of Reading in Berkshire, England, used the formula to calculate that the beast had to attain an air speed of only 15 m.p.h. to take off. In winds above that velocity, they report in Nature, Pteranodon would only have needed to spread its wings to become airborne, easily taking off from level ground or the crest of a wave. "Thus," conclude Bramwell and Whitfield, "many of the problems envisaged by paleontologists for the pterosaurs did not exist for the pterosaurs themselves."

* More than twice as long as that of the largest contemporary bird, the albatross.

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