RE: Isanosaurus question

[Mark Hallett <marksabercat@yahoo.com>]

Quite so. 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. Mark Hallett
--- "T. Michael Keesey" <mightyodinn@yahoo.com> wrote:
> > -----Original Message-----
> > From: owner-dinosaur@usc.edu
> [mailto:owner-dinosaur@usc.edu]On Behalf Of
> > DRosent288@aol.com
> > Sent: Sunday, April 14, 2002 8:00 PM
> > To: dinosaur@usc.edu
> > Subject: Isanosaurus question
> > 
> > If sauropods were already around in the late
> Triassic, woudn't that pretty
> > much kill
> > the idea that sauropods are descended from
> malanorosaurid prosauropods such
> > as melanorosaurus or riojasaurus?
> 
> Not necessarily ... there could have been something
> like _Melanorosarus_ or _Riojasaurus_ living
> before _Isanosaurus_. Absence of evidence is not
> evidence of absence, which is why stratigraphy
> can be a poor indicator of phylogeny, especially for
> such a sparsely-known group.
> 
> Also quite possible (probable?) that _Sauropoda_ are
> descended from another group of "prosauropods".
> 
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> =====> T. Michael Keesey <keesey@bigfoot.com>
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