Pelvis of *Avimimus*

["Jaime A. Headden" <qilongia@yahoo.com>]

David Marjanovic (david.marjanovic@gmx.at) wrote:

<BTW, the fourth author is Xabier Pereda Su_b_erbiola.>

  My boo ... thanks.

<While I am at it, I've finally looked at the fossil, and as expected 
*Confuciusornis* has a
proximally broadened mtIII like *Iberomesornis* and *Yandangornis*.>

  This is the plesiomorphic condition for birds, actually. First with the 
theropod normal
condition of evenly broad third--fourth metatarsals, to the expansion in 
confuciusornithids and
higher birds. All higher birds have broad third metatarsals up to the advanced 
enants (broadening
of the fourth) to modern cursorial and passeromorph birds, which narrow the 
metatarsus to the
point that the condition is negligent.

<Unfortunately the beast is in ventral view*, so it's totally impossible to 
determine what its
pelvis looked like in dorsal view, which means I still can't add the state 
"ilia very close
together craniodorsally, so that their dorsal margins are sigmoid and are fused 
to the neural
spines, but very far apart caudally" to my matrix where it would presently be 
an autapomorphy of
*Avimimus*.>

  Odd how you describe a bird as a beast, but anyway ... the ilia of *Avimimus* 
are not fused to
the neural spines, which are also separate from one another and do not form a 
lamina, as they do
in birds. The ilia have a slight separation from the ilia, in fact, and there 
are two separate
features which ally them to the condition in modern birds (see Kurzanov, 1987): 
the wide lateral
flare of the postacetabular ala, and the sagittal inclination of the dorsal 
margin of the ala.
Various other animals have a sigmoid curvature of the ilia, including 
dromaeosaurids. The lateral
flare of the ilia caudally has also been proposed for *Archaeopteryx,* and is 
present to some
degree as in dromaeosaurids, oviraptorosaurs, *Caudipteryx,* and segnosaurs, in 
spite of the
lateral flare of the preacetabular alae. So you are looking at more than one 
character.


=====
Jaime A. Headden

  Aaaaaaaaaaaaaaaaaaaahhhhhhhhhhhhhhhhhhr-gen-ti-na
  Where the Wind Comes Sweeping Down the Pampas!!!!

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