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The Radius as a Locomotion Predictor in Quadrupeds
Germain, D. & M. Laurin. 2005. Microanatomy of the radius and lifestyle in
amniotes (Vertebrata, Tetrapoda). _Zoologica Scripta_ 34(4):335-350.
"Radial cross-sections of 49 species of extant and two species of extinct
amniotes of known lifestyle have been studied in order to assess the
relationship between lifestyle (aquatic, amphibious or terrestrial) and bone
microanatomy. Most compactness profile and body size parameters exhibit a
phylogenetic signal; therefore, classical statistical tests should not be
used. Permutational multiple linear regressions show an ecological signal in
most compactness profile parameters and in the cross-section maximal
diameter. A linear discriminant analysis is performed with these parameters
to distinguish the various lifestyles. The discriminant function based on
taxa of known lifestyle is used to infer the lifestyle of three extinct
amniotes: the early nothosaur *Pachypleurosaurus* (amphibious), the
*Lystrosaurus* (amphibious) and the synapsid *Ophiacodon* (aquatic). These
predictions are congruent with classical palaeoecological interpretations.
This model may be very useful when attempting to infer the ancestral
lifestyle of amniotes and other early limbed vertebrates."
While it helps to determine a predictor model in locomotion strategies, it
doesn't help in bipeds as the radius is not a weight-bearing-bone in bipeds.
However, climbing and winged mammals/birds may also show comparable testing in
the way the radius is loaded, and this may be tested using radial
cross-sections. Our own Mike Habib is working on aspects of this, but for
Jaime A. Headden
Little steps are often the hardest to take. We are too used to making leaps
in the face of adversity, that a simple skip is so hard to do. We should all
learn to walk soft, walk small, see the world around us rather than zoom by it.
"Innocent, unbiased observation is a myth." --- P.B. Medawar (1969)
"Human beings, who are almost unique in having the ability to learn from the
experience of others, are also remarkable for their apparent disinclination to
do so." --- Douglas Adams
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