Noasaurids (was Re: New Sauropod from Portugal)

[Tim Williams <twilliams_alpha@hotmail.com>]

Luis Perez wrote:

> Hi. I'm doing a hypothetical reconstruction of Noasaurus for my senior 
> project, and I was wondering if anyone knew where I could find Journals on 
> Noasaurus and Dinosaur Reconstructions
> in general or even the "Noasauridae"

The noasaurids are a very intereresting group, but it's difficult to get a 
handle on their overall morphology.  _Noasaurus_ itself is very poorly 
known, as is _Ligabueino_ and especially _Laevisuchus_.  _Masiakasaurus_ and 
_Deltadromeus_ are better known, but their skeletons are only about 40% 
complete (for _M_, this is the combined result from several individuals).

> (Masiakasaurus, Ligabueino, Deltadromeus (is it
> really a big Noasaur? What makes a Noasaur a Noasaur?))

The original description of _Deltadromeus_ regarded it as a basal 
coelurosaur, like _Ornitholestes_ (Sereno et al., 1996), but a later 
analysis reassigned _D_ to the Noasauridae (Sereno et al., 2004).  Time will 
tell whether either hypothesis has legs.  Speaking of legs, the character 
that was cited by Sereno et al. (2004) to unite Noasauridae (including 
_Deltadromeus_) was "metatarsal IV distal end reduced".  Potentially 
complicating matters is the unresolved issue over whether _Deltadromeus_ is 
the same theropod as _Bahariasaurus_.

Carrano et al. (2002) put _Laevisuchus_ in the Noasauridae, with _Noasaurus_ 
and _Masiakasaurus_.  _Noasaurus_ and _Masiakasaurus_ share: cervical neural 
spine placed on the anterior half of the centrum; reduced shaft of 
metatarsal II; simple maxillary palatal process; prominent rim on the 
antorbital fossa.  _Laevisuchus_ has the first character in common with _N_ 
and _M_, as well as postzygapophyses that are swept back strongly 
posteriorly.

_Masaiakasaurus_ has an interesting lower jaw morphology, in that the front 
teeth are procumbent and are positioned below the level of the ventral 
margin of the dentary.  It is not known whether this feature is shared by 
all noasaurids, because this part of the skull is lacking in other taxa 
(AFAIK).

Bonaparte (1995) provisionally assigned _Ligabueino_ to the Noasauridae, but 
it is not clear if it is a member of this clade, although it is certainly 
some kind of small abelisauroid.  Also, _Velocisaurus_ may be a noasaurid, 
and maybe _Jubbulpuria_ and _Coeluroides_ too.  These three taxa are all 
very poorly known (the last two are probably nomina dubia).

Cheers

Tim

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