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Estimating body mass from silhouettes: testing the assumption of elliptical body cross-sections

Published online by Cambridge University Press:  20 May 2016

Ryosuke Motani*
Affiliation:
Department of Palaeobiology, Royal Ontario Museum, 100 Queen's Park, Toronto, Ontario M5S 2C6, Canada. [email protected]

Abstract

In computational studies of the body mass and surface area of vertebrates, it is customary to assume that body cross-sections are approximately elliptical. However, a review of actual vertebrate cross-sections establishes that this assumption is not usually met. A new cross-sectional model using superellipses is therefore introduced, together with a scheme that allows estimates to be given with ranges. Tests of the new method, using geometrical shapes, miniature vertebrate models, and actual animals, show that the method has a high accuracy in body mass estimation. A new computer program to perform the computation is introduced. The application of the method to some Mesozoic marine reptiles suggests that the tuna-shaped ichthyosaur Stenopterygius probably had body masses comparable to those of average cetaceans of the same body length.

Type
Articles
Copyright
Copyright © The Paleontological Society 

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References

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