The Radius as a Locomotion Predictor in Quadrupeds

["Jaime A. Headden" <qilongia@yahoo.com>]

  Germain, D. & M. Laurin. 2005. Microanatomy of the radius and lifestyle in
    amniotes (Vertebrata, Tetrapoda). _Zoologica Scripta_ 34(4):335-350.
   (doi:10.1111/j.1463-6409.2005.00198.x)

Abstract:
  "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
therapsid
   *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
different purposes.

  Cheers,

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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