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Re: In Re: David's Statements



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

<...I was referring to pneumatic foramina in vertebrae and
ribs.>

  I admit that I am not really comprehensive on vertebral
pneumaticity, and only recently has this been quantified
throughout theropods, and most of dinosaurs. Brooks Britt and
Pete Makovicky have worked on the most comprehensive analyses of
pneumaticity in dinosaurs, primarily theropods, and both have
done their PhD theses on this.

 --- as an aside, I would be very grateful if anyone can help me
to acquire these theses (Brooks and Makovicky), as attempts to
contact either have not helped me much; also, publicly, attempts
to acquire Raath's thesis, where he himself is left with his own
copy, and Rhodes University will charge me well over $50 to gain
this (I will as a last resort, but if I can get it cheaper...)
---

<I was referring to the upper (dorsal) end of the quadrate,
wasn't I?>

  You were referring to the use of a double-headed quadrate.
Personally, to understand the "use" of a quadrate with both an
otic (posteromedial) and squamosal (lateral) head, one has to
understand the use of this structure in a single-headed quadrate
and the quadrate in general. Prokinesis cannot, by definition,
operate without a mobile quadrate (i.e., single-headed, loose
contact with quadratojugal).

<<though is ossified as a "rod," and this suggests the union is
ligamentous.>>

<Oho! A ligamentous union... Isn't this still more like a
pygostyle than the plesiomorphic condition? :-)>

  No, it _is_ the plesiomorphic condition, and one can see that
the distalmost caudals of most dinosaurs have reduced non-centra
articulations, no neural spines, and no transverse processes,
suggestive that the primary connection is ligamentous. There are
two alternatives with morphology: fusion, and reduction of
count.

---

Elsewhere, I wrote:

<<Ornithomimosauria == { (Pelecanimimus + Ornithomimus) } (I
don't believe this taxon has been strictly defined: Sereno's
[horribly restrictive] usage for Ornithomimidae is {
Pelecanimimus + Ornithomimus } and by the phylogeny of Osmólska
and Barsbold, 1994 and Perez-Moreno et al., 1994, this would
correspond to Ornithomimosauria, which has priority by taxonomic
foundation, and the definition shifts to Ornithomimosauria)>>

<Sure?>

  It hasn't been formally stated, but in use of phylogeny, this
is the next taxon that _can_ bear the definition, and this is
the usual practice. It _should_ be explicitly stated. 

[Speaking of Paraves]

<Odd name for a group that includes Aves. :-( .>

  para-, "around or beside" + Aves, birds; can be used then to
mean "around Aves" or "containing Aves."

<<Furthermore, the "lagosuchid" dinosauriforms have homodont,
ziphodont jaws that appear to be carnivorous rather than insect
eating.>>

<Oh! wasn't talking of anteater-style insectivory, of course...>

  Neither was I. Myrmecophagy involves different mechanical and
dental morphology. Generally, you really don't need teeth to eat
an insect, just a pulverizing mechanic. Anteaters use their
gizzard for instance, and most insectivorous avians and bats use
their palates....



=====
Jaime A. Headden

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

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