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Re: Epidendrosaurus Phylogenetic Discussion Pt. 2



ekaterina A wrote-

> >         `--+--+--Harpymimus
> >            |  |--Pelecanimimus
> >            |  |--Garudimimus
> >            |  `--+--Struthiomimus
> >            |     `--Gallimimus
>
> Harpymimus, Garudimimus come out about as primitive as
> Pelecanimimus ? I thought that the latter had many
> primitive features that should make it the sister
> group of all other O'mimosaurs?

That means that the three basal genera are in a polytomy with the more
derived ones.  It does not mean that they are all equally primitive, just
that the characters didn't let PAUP decide which was most primitive.
Incidentally, Harpymimus may be more primitive than Pelecanimimus.

> >                                 |--Conchoraptor
> >                                 `--GI 100/42
>
> What is this GI 100/42? Was Nomingia included? Also
> for Cheirostenotes and Avimimus, did you include the
> new (unpublished?) specimens. Have you all included
> Scansoriopteryx too? What are the Synapomophies of the
> oviraptorosaur clade that Avimimus shows?

GI 100/42 is the cassowary-crested "Oviraptor", better referred to as
Citipati sp..  Nomingia was not included.  Only Xu et al.'s codings were
used for all taxa (except Jaime revised the manual ungual I size character
and its codings), so the undescribed Chirostenotes and Avimimus specimens
were not included.  Same for Scansoriopteryx.  The characters supporting an
oviraptorosaurian position for Avimimus in Xu et al.'s matrix are-
- crenulate ventral premaxillary edge
These appear to have been reidentified as teeth by Watabe et al. (2000).
- paroccipital processes curve ventrally
- coronoid prominence on surangular
Not found in Caudipteryx.
- retroarticular process elongate and slender
Not found in Caudipteryx, but is in a wide variety of other coelurosaurs
including Shuvuuia.
- elongate mandibular articulation capable of sliding
In addition, it shares the following with Chirostenotes-
- ischium <66% of pubic length
The distal ischium of Avimimus is unknown, but this ratio is shared with all
eumaniraptorans except derived birds.
- arctometatarsalian
Found in several other taxa of course.
Although placement of Avimimus within Oviraptorosauria seems possible,
Chirostenotes and oviraptorids almost certainly are more closely related to
each other than Avimimus is.

> There seems to be a strong biomodal fit for
> Epi'den'saurus the distribution of your trees.. is
> that correct? Would this mean there is some possiblity
> of chimerism of this specimen as Dr. Holtz had
> obliquely hinted

As Jaime explained, there is very weak support for each position once the
matrix was corrected.  One character suggesting eumaniraptoran affinities,
one enigmosaurian affinities.  This seems due more to the lack of coded
characters than conflicting data.  My results to come shortly....

Mickey Mortimer