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Re: Moroccan noasaurid?



Mickey Mortimer (Mickey_Mortimer111@msn.com) wrote:

<... "bone taxon A" of Russell 1996.  This is based on two skull roofs
(NMC 50807- frontals and parietals; NMC 50807- frontals) from the Albian
Gres Rouges Infracenomaniens of Morocco.  They are rather small (frontal
lengths of 50 mm and 65 mm), but firmly coossified.  What intrigued me was
the fact there is a sagittal crest on the parietals.  This character is
otherwise only known in abelisaurids, "Alas.... er "Chilantaisaurus"
maortuensis :-) , tyrannosaurids and some more derived coelurosaurs.>

  Actually, some basal oviraptorids have strong sagittal crests, as well,
only some abelisaurids have the crest and these are generally carnotaurine
(specifically, *Aucasaurus,* *Majungasaurus,* *Carnotaurus,* and
*Indosaurus*), or are tapered from the interparietal plateau caudally (as
in "abelisaurines" like *Abelisaurus* and *Indosuchus*. This occurs in
some allosauroids, as well. Many of these taxa have robust jaw muscles and
the condition of an advanced sagittal crest is often correlated (at least
in mammals) to jaw size, function, and even ontogeny -- -this has been
explicitly tested in many carnivoran mammals, especially hyaenids,
ursines, and cats.

<Comparing it to Troodon indicated the cerebral hemispheres were much
smaller, suggesting this is not a coelurosaur.  Although rather small and
elongate for an abelisaurid, the fact noasaurids are closely related (and
have unknown frontals), of similar size and are also known from Africa
(Masiakasaurus) makes me ponder a noasaurid affinity for the taxon.  The
humerus NMC 41873 also resembles Masiakasaurus in general proprtions and
may derive from the same taxon.  Any thoughts?>

  The frontals have advanced stereoscopic properties, with the preserved
orbital rib having features of a maniraptoran quality, so that the
interorbital margins are parallel, only just wider than long, with a
caudal margin turned laterally at around 45 degrees to the midline. the
olfactory bulbs preserved at the very rostral end of the frontal,
underlying the scarf joint with the nasals, are very broad and elongated,
and the caudal margin displays complex supracranial sinuses along the
contact with the laterosphenoid, suggesting the latter was pneumatic as
were other portions of the braincase. The orbital margin is deflected
dorsally and it is clear that it would have provided a shallow arch for
the eyeball, and that this organ was fairly large. The animal was probably
maniraptoriform, and the lateral and dorsal orientation of the lateral
wings of the frontals suggest it was maniraptoran.

  As for NMC 41873, this bone possesses a distal end whose shape is
ginglymoidal in aspect with a length and width of the articular end being
much narrower than expected for its length. What may be a supracondylar
crest (ent- or ectepicondylar) is present on one side, and the other has a
flange that is probably the rim of the condyle and not a crest. The distal
end bears a ligamental pit not found on humeri, and this data suggests
that the bone is either a metacarpal or metatarsal bone of some length.

<Reference- Russell, D.A. 1996. Isolated dinosaur bones from the Middle
Cretaceous of the Tafilalt, Morocco. Bulletin du Muséum national
d'Histoire naturelle (4e séries) 18:349-402.>

  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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