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Re: Coelurus a maniraptoran (for how long?)



> > However, pneumatic fossae are something that is either present or
absent,
> > and ontogenetically p. foraminae develop from p. fossae, in chickens at
> > least.
>
> But in oviraptorids, they seem to be foramina from at least the embryonic
> stage.

I still wonder why... Maybe fossae and foramina should be coded as separate
characters?

> > Neither the original description of *C. zoui* in Nature nor that of *C.
> > dongi* in Vertebrata PalAsiatica mention any sacrum, and I can't see any
> > in the illustrations in these articles. Is this also based on ilial
length?
>
> The original description (Ji et al., 1998) states- "There are ten
> amphicoelous cervical vertebrae and five sacrals as in most non-avian
> theropods and Archaeopteryx."

Must have overlooked that...

> > > In addition, Alxasaurus, Nanshiungosaurus? bohlini and
Nanshiungosaurus
> > > brevispinus have only five sacrals.
> >
> > :-(
> > Reduction due to

less stress, such as

> > less running?
>
> The dinosaur taxa with the most sacrals (ankylosaurs, hadrosaurs,
> ceratopsids) weren't exactly cursorial.  And Segnosaurus did have six
sacral
> vertebrae.

Maybe the number of sacrals is only applicable to small dinosaurs, because
it often increases with weight (more exactly, stress on the sacrum) in large
ones... which would force me to define small and large.

> > Is a sacrum known for *Oviraptor*?
>
> [...] it's perhaps better to say
> that Conchoraptor has six sacral vertebrae.

At least this is consistent with *Chirostenotes*...

> Regarding the transition point in theropods, I believe it is defined by
the
> absence of transverse processes.

I believe it is defined by restricted mobility distally to it...

> In this case, Shuvuuia (the "Mononykus"
> picture of Perle et al., 1993)

This picture is a composite restoration of the holotype of "Mononychus" and
the referred specimen that is now referred to *Shuvuuia*.

> shows a transition point after nine caudals.
> Other characters (centrum elongate, neural spine absent, chevrons
skid-like,
> elongate prezygopophyses, etc.) may also be present, but this varies with
> the taxon.  I don't think the fact the distal tail wasn't stiff would keep
> alvarezsaurids from having a transition point.  You're right to state
> alvarezsaurids lack elongate prezygopophyses on distal caudals.  This is a
> synapomorphy shared with several other coelurosaurs (Coelurus,
> Compsognathus, therizinosauroids, Microvenator, caenagnathoids,
troodontids,
> Rahonavis and Archaeopteryx), although I'm sure you would agree Coelurus,
> Compsognathus, troodontids, Rahonavis and Archaeopteryx still have
> transition points.

With "elongate", I didn't mean as elongate as in dromaeosaurids... though I
don't really know how long they usually are, and I might have to classify
those on the distal caudals of *Nomingia* as elongate.

> Therizinosauroids, Microvenator and caenagnathoids are
> the only tetanurans without a transition point, even Caudipteryx and
> Nomingia have one.

While I'm not sure on the latter two, I'll admit that I don't know enough
about transition points (early realization... :-] ), but I'll cling to a
short, mobile tail.

> > Could you enlighten me on details?
>
> There are quite a few characters that support the Metornithes in Chiappe
et
> al.'s (1998) matrix.  However, most of these are problematic.
> 6.   Postorbital-jugal contact: present (0), absent (1).
> The postorbital bar is complete in Confuciusornis, suggesting Shuvuuia
> developed it in parallel.

Or that confuciusornithids reversed this to have a stronger bite (some
consider them folivorous). The fact that *Confuciusornis* has an ascending
process on the jugal, unlike *Shuvuuia*, may cast doubt on this, however.
Chatterjee regards the skull of *Avimimus* as secondarily akinetic (and puts
*Avimimus* as the sister group of Alvarezsauridae).

> 19.  Hyposphene-hypantrum accessory intervertebral articulations in dorsal
> vertebrae: present (0), absent (1).
> Although Chiappe et al. code Patagonykus as having this character, it is
> absent in this genus(Novas, 1997).

This paper states explicitely that *P.* has the plesiomorphy, doesn't it?

> 39.  Sternum subquadrangular to transversally rectangular (0) or
> longitudinally rectangular (1).
> [...]
> Indeed, it can be seen that Mononykus has an exceptionally narrow sternum,
> while the proportions in basal pygostylians are similar to those in
> dromaeosaurs.  I think you'll agree there is no support for Metornithes
> here.

Definitely. Additionally, sterna are preserved too rarely and often ossify
too incompletely to make this character informative.

> 40.  Ossified sternal keel: absent (0), present (1).
> Confuciusornis only occasionally has a faint keel (two specimens), while
the
> keel is caudally restricted in Protopteryx and absent in Changchengornis.
> So whether this is a good metornithine character or not is very debatable.

Probably not. More fossils would be nice, of course, as always...

> 54.  Distal carpals and proximal portion of metacarpals unfused (0), or
> fused forming a carpometacarpus (1).
> An extremely variable character. [...]
> Thus, I think Mononykus developed this in parallel to the
> partial development in confuciusornithids, the development within
> enantiornithines and the development in euornithines.

I agree. ;.-(

> 64.  Prominent antitrochanter: absent (0), caudally directed (1), or
> dorso-caudally directed (2).
> This is fine, though also present in Avimimus.

No real problem, as some people put *Avimimus* next to or even into
Metornithes. This would mean, however, that its arctometatarsality and its
?oviraptorosaurian characters are all convergences.

> So out of the sixteen metornithine characters, seven are valid, assuming
> some parallel development or close relationship of a few taxa (usually
> Rahonavis, troodontids or Avimimus).  All of these are included in my
> analysis, and dromaeosaurs, Rahonavis and Archaeopteryx are always closer
to
> pygostylians than alvarezsaurids are.

Now I'm curious what characters still unite dromaeosaurs and *Archaeopteryx*
with pygostylians... :-> Could you explain them, if you have the time, of
course?

> The most you could get away with would be coding
> Caudipteryx as "?" for pygostyle present.

Still fine! (Unless someone looks at its last caudal with a microscope,
probably.) :-)