Wednesday, April 29, 2009

Albatross vs. Pterosaur

ResearchBlogging.orgToday, there was a paper tangentially related to pterosaurs in the open access journal PLoS ONE. A team of investigators wired up albatrosses and petrels with accelerometers, in order to measure the percentage of time these animals spent flapping their wings and soaring. They found two main styles of wing flapping (as inferred from the accelerometer measurements): 1) high frequency flapping during take-off; and 2) low-frequency flapping during soaring. Interestingly, the frequencies scale with body mass in such a way that a maximum possible body size for the albatross-like body plan that still allows flight is extrapolated to a body mass of 41 kg and wingspan of 5.1 m (with the requisite error bars, of course).

The authors then go on to discuss the implications for pterosaur paleobiology, essentially suggesting that albatross-style soaring was physically impossible for pterosaurs such as Quetzlcoatlus (assuming that it also had albatross-style wings). Frustratingly, there is little discussion of the alternative possibilities of wing shape in pterosaurs, among other things. Furthermore, the underlying data for the analysis only focus on four species of birds with limited morphological diversity. As suggested by the authors of the current paper, data on thermal-soaring birds such as condors (which have a decidedly un-albatross-like form) are sorely needed.

So, kudos to Sato et al. for collecting some interesting morphological data. This sort of information is invaluable for verifying and refining existing models of vertebrate flight. However, the relevance of the data to pterosaurs should probably be reviewed by someone who knows the group better than I do - so if you're one of those people, hop (or soar) on over to PLoS ONE and comment on the article!

Reference
Sato, K., Sakamoto, K., Watanuki, Y., Takahashi, A., Katsumata, N., Bost, C., & Weimerskirch, H. (2009). Scaling of soaring seabirds and implications for flight abilities of giant pterosaurs. PLoS ONE, 4 (4) DOI: 10.1371/journal.pone.0005400

3 comments:

Zach said...

Yeah, don't know about this one. I mean, there must be a theoretical size limit to flying vertebrates (or invertebrates), and I'll bet dollars to doughnuts that azhdarchids were at that maximum. My biggest problem with enormous flying pterosaurs is how they got off the ground. That quadrupedal leapfrog thing is great, but how high are they springing into the air? The second they start "flapping" (and could they flap those giant wings?), gravity kicks in. They'd better be able to flap quick and forcefully, you know?

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