Sato K, Sakamoto KQ, Watanuki Y, Takahashi A, Katsumata N, et al. (2009) Scaling of Soaring Seabirds and Implications for Flight Abilities of Giant Pterosaurs. PLoS ONE 4(4): e5400. doi:10.1371/journal.pone.0005400
Abstract: The flight ability of animals is restricted by the scaling effects imposed by physical and physiological factors. In comparisons of the power available from muscle and the mechanical power required to fly, it is predicted that the margin between the powers should decrease with body size and that flying animals have a maximum body size........ These scaling relationships predicted that the maximum limits on the body size of soaring animals are a body mass of 41 kg and a wingspan of 5.1 m. Albatross-like animals larger than the limit will not be able to flap fast enough to stay aloft under unfavourable wind conditions. Our result therefore casts doubt on the flying ability of large, extinct pterosaurs. The largest extant soarer, the wandering albatross, weighs about 12 kg, which might be a pragmatic limit to maintain a safety margin for sustainable flight and to survive in a variable environment.
Available for free download at: http://www.plosone.org/article/info%3Adoi%2F10.1371%2Fjournal.pone.0005400
Andy
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