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Re: Therizinosauroid apomorphies [long!]



Jaime Headden wrote-

>   The obturator process is displaced to the very
> distal end of the ischium in *Nanshiungosaurus
> brevispinus*, which is an autapomorphy of the genus
> and possibly species (I've yet to see the papers for
> both species of Nan, so....).

The pelvis of Nanshiungosaurus bohlini is unknown. Holotype- (IVPP V.11116)
eleven cervical vertebrae, five dorsal vertebrae, fragmentary ribs.

>   <-dorsoventrally expanded, laterally directed
> anterior iliac blade (nanshiungosaurus, segnosaurus)>
>
>   And most herbivorous mammals. :) *Beipiaosaurus*
> also has this condition, though to a less derived
> degree, according to Xu (pers. comm.).

Laterally directed, perhaps.  Dorsoventrally expanded more than other
coelurosaurs, no (unless the figure in Xu et al. 1999 is very misleading).

>   I list the following synapomorphies for ovis +
> therizinos:
>
>   1-edentulous premaxillae [teeth in *Caudipteryx*]

Also in several coelurosaur groups.

>   2-basipterygoid processes reduced

Present in birds as well, of course.

>   3-medially inflected dentary [also in troodontids]

...and ornithomimosaurs.

>   4-lateral depression in the middle-ear cavity [same]

Are you sure this is true of oviraptorids?

>   5-no maxillary fenestra [present in oviraptorids?]

I believe it is present in oviraptorids, and in Caudipteryx.

>   6-caudals reduced to 35 or less

Same with lots of maniraptorans (Protarchaeopteryx, troodontids, Mononykus,
Rahonavis, avians)

> 8-posterodorsal lip on first manal ungual, sometimes on other unguals

Also in Deinocheirus and some others.  Absent in Caudipteryx.

>   Six of these may be autapomorphic, which I think is
> substantial enough. If someone could run them in Paup
> or MacClade... [Do you DELTRAN or ACCTRAN, Mickey?]

All of those characters are indeed in my database.  Therizinosaurs (which I
plan to code as a few separate OTU's in the future) do group with
oviraptorosaurs, and Protarchaeopteryx at times.  Avimimus now comes out as
an alvarezsaur relative, not an avialan.  I use DELTRAN to avoid diagnosing
clades with characters that may not have been present that early.  You did a
great job summing up the main synapomorphies grouping these two clades
together.  I only have the following to add*:

 - frontal process of premaxilla/caudal margin of naris nearly reaching
rostral border of antorbital fossa (also in Ornitholestes, Scipionyx,
Sinornithosaurus, Avimimus and Aves)
 - palatal shelf on premaxilla and anterior maxilla (also in
Ornithomimosauria and Avimimus)
 - nasal subequal in length to frontal (also in Compsognathidae and Aves)
 - two pairs of pleurocoels in cervical vertebrae (also in Variraptor and
Avimimus(?))
 - prezygapophyses on distal caudal vertebrae short or absent (also in
Compsognathidae and Avialae)

* These are characters resulting from an earlier analysis done last year on
PHYLIP.  I don't know how to create lists of what characters define what
taxa in PAUP yet.  If anyone knows, please respond off-list.  Thank you.

>   Six sacrals are known in *Velociraptor* (Norell and
> Makovicky, 1997), *Gallimimus* (Osmolska et al.,
> 1972), and troodontids (Barsbold, 1976; Currie, 1990;
> Paul, 1988).

And in mononykines (at least it's always coded that way, I have no proof
personally)Unenlagia and Rahonavis.  Alxasaurus and Caudipteryx have only
five.

Cervical and presacral pneumatization is
> variable, and *Microvenator* lacks pleurocoels,
> *Achillobator* has cervical, dorsal, and caudal
> pleurocoels (Perle et al., 1999); Caenagnathidae and
> Therizinosauroidea may have aquired their pairs
> separately because *Caudpteryx,* *Avimimus* and
> *Microvenator* lack the condition -- this is of course
> assuming they are within Ovi + Theriz.

I assume you mean Microvenator lacks caudal pleurocoels.  Avimimus may have
double cervical pleurocoels, as seen in the figure in The Dinosauria (a
small secondary pleurocoel being placed directly ventral to the neural
spine).  Microvenator does have double cervical peurocoels and the relevant
data of Caudipteryx is unpublished.

Mickey Mortimer