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Noasaurids (Re: Late Triassic Footprints with Reversed Hallux)



Mike Keesey (mightyodinn@yahoo.com or keesey@bigfoot.com) wrote:

<Other than _Avialae_, are there any theropodan lineages likely to have
had a reversed hallux? _Noasauridae_ seem to have been doing strange
things with their pedes: the enlarged ?hyperextendable second pedal digit
of _Noasaurus leali_, the "anti-arctometatarsalian" pes of _Velocisaurus
unicus_.... And doesn't _V. unicus_ lack a first pedal digit?>

  Lack of preservation doesn't mean it wasn't there, but the pes of
*Velocisaurus* is slender enough to suggest reduction to three toes
entirely.... All other "sickle-claw" theropods have a first toe, though,
but this does not mean any noasaurid lacked it or possessed it. There may
or may not always be a facet for articulation of the first metatarsal, as
has been clear with problems of articulating a disarticulated first
metatarsal.

<Of course, _Noasauridae_ first appear in the fossil record even later the
_Avialae_ (or at least around the same time, if _Elaphrosaurus bambergi_
is noasaurid as HP Mortimer suggests), but is it possible the prints might
belong to some other sort of small ceratosaur?>

  Why ceratosaur?

  As for Mickey's suggestion of a noasaurid *Elaphrosaurus*, this depends
first on a definition or usage of Noasauridae, hardly defined, and only
tentatively has included *Velocisaurus* since the *Masiakasaurus* analysis
was published and suggested (but did not indicate) a link. Most of the
apomorphies for affinities of *Elaphrosaurus* depend on comparison to
*Masiakasaurus* at present, but there are instead studies published by
Coria, Salgado, and Sereno, that support *Elaphrosaurus* as the sister
group to Abelisauridae, and the taxon Abelisauroidea is defined as the
most recent common ancestor of *Elaphrosaurus* and *Abelisaurus* (Sereno
uses *Carnotaurus*). These are defined, among other things, by fusion of
the proximal tarsals to the tibia, proximal tarsals to one another,
proximal L-shape for metatarsal III, lacking in "noasaurids". The first is
questionable, though. Vertebral features are either plesiomorphic or
age-dependant, though some features of the zygapophyses are unique, and
noasaurids in the broadest sense do not have them.

  Noasauridae is, as of the most recent analyses of the Argentineans, the
sister group to Abelisauroidea, and is the most basal clade aside from
*Ligabueino* as published. *Ligabueino* may have more restrictive
relationships, but this is unpublished and in prep. Presently, an analysis
of "noasaurids" and basal abelisaurs needs to be done and is not, but it's
one thing I am personally looking into. You'll probably see something on
my website before I ever publish it...

  basal abelisaurs are:

  *Ligabueino andesi*
  *Noasaurus leali*
  *Velocisaurus unicus*
  *Masiakasaurus knopfleri*
  *Quilmesaurus curriei*
  *Elaphrosaurus bambergi*

  *Genusaurus sisteronis* is a "ceratosaur" with features similar to basal
ableisaurs. I will be covering this on my website ... with illustrations
:).

  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.

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