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Re: Avimimus!!



--- Mickey Mortimer <Mickey_Mortimer111@msn.com>
wrote:

> 
> This describes several avimimid elements from the
> Iren Debasu Formation
> (Campanian?)

 Do they say that? I thought the Baynshirenskayasvita
is Santonian or older.



> of China.  The orbital margin of a
> frontal (TMP 92.302.104) is
> difficult to compare to A. portentosus, but is
> similarily bulbous over the
> orbits.  There is an anterior dorsal (TMP
> 92.302.140) that resembles the
> second of Avimimus, but has a shorter hypapophysis
> and more ventrally placed
> parapophyses.  Another vertebra (TMP 92.302.344) was
> not identified
> specifically, but appears to be a mid caudal.  There
> seem to be two small
> lateral foramina, the centrum is not quadrangular in
> section and a low
> neural spine is present.  A partial fused
> scapulocoracoid (TMP 92.302.116)
> is shown, with a ventrally directed glenoid and low
> coracoid tubercle.  It
> is very comparable to the holotype, but more
> incomplete, lacking the ventral
> coracoid tip, most of the anterior edge and all but
> the base of the scapular
> shaft.  A proximal humerus (TMP 92.302.117) is
> extremely similar to the
> holotype, differing only in minor proportional
> details.  Both proximal (TMP
> 92.302.149) and distal (TMP 92.302.110) femoral ends
> are known.  The former
> differs from the holotype in the more lateromedially
> compressed greater
> trochantor and less prominent anterior trochantor in
> proximal view.  The
> distal femur has less extensive articular surfaces
> in anterior view and a
> less prominent lateral condyle.  In distal view, it
> is less convex
> anteriorly.  A proximal tibia (TMP 92.302.150) is
> quite different from A.
> portentosus, having a bulbous lateral condyle, less
> dorsally projected
> cnemial crest, and small posterior process in
> proximal view.  The proximal
> metatarsus (TMP 92.302.102) is very similar
> anteriorly and posteriorly, but
> is differently shaped proximally, being
> parallelagram-like.  Another
> metatarsus (AMNH 6755), this one complete except for
> the proximal portion of
> metatarsal III, is quite unique.  It was found in
> the Central Asiatic
> Expeditions of 1923 along with another third
> metatarsal (AMNH 6764).  This
> metatarsus is arctometatarsalian, but the third
> metatarsal extends up 90% of
> the metatarsal length in anterior view (and almost
> as much posteriorly).
> This contrasts with 45% in A. portentosus.  This
> metatarsus is less slender
> than the latter, with a more reduced fourth
> metatarsal and no fifth
> metatarsal fused to it.  I'm not altogether
> convinced this is an avimimid
> and not a caenagnathid, for instance.  Two pedal
> unguals (TMP 92.302.119A
> and B) are quite odd.  They are markedly
> asymmetrical, having smaller
> lateral halves with much higher grooves on that
> side.
> 
> Mickey Mortimer
> Undergraduate, Earth and Space Sciences
> University of Washington
> The Theropod Database -
> http://students.washington.edu/eoraptor/Home.html
> 



                
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