RE: Isanosaurus question

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

Mark Hallett (marksabercat@yahoo.com) wrote:

<The presently known taxa of prosauropods must be ruled out as sauropod
ancestors because the outermost pes digit(#5)was in these extremely
vestigial and on its way out, whereas sauropods retained all five as
functional toes. This does not mean, however, that some unknown basal
melanorosaurid or other prosauropod group earlier in the Triassic that
retained all five digits could not be ancestral to the Vulcanodontidae,
the most basal sauropod family.>

  Or ... big or, as has been pointed out before on the list ... sauropods
have expanded the nature of the outer metatarsals, in response to their
load-bearing on the foot and the shortening of the pes, which makes the
metatarsals "appear" longer. There is no parsimonious way to explain this
... sauropods have a novel pes design, and it can hardly be considered
plesiomorphic compared to advanced prosauropod feet because there really
isn't a foot quite like the sauropod pes.


=====
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.

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