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In Re: David's Statements



David Marjanovic wrote:

<<Maybe I can "explain this away" that the actual character here
is not the hole in the bone, but the presence of the air sac,
which may or may not invade the bone due to ontogenetic age or
whatever. Of course, this is hardly falsifiable...>>

... and Mickey Mortimer replied (and further in the post):

<Sure..... That will hold up in court.... ;-)>

  Seconding Mickey here, this is not a good position to take.
Currie is very well respected in his field as is among the [if
not _the_] top theropod researchers and experts in the world, to
which Holtz, Molnar, and Chure can add their names. Countless
hours and weeks in front of the actual specimens has given them
a considerable experience in telling us if cranial nerve V
(trigeminal) has a separate exit for the ophthalmic branch,
which is largely discernible only from within the bone, and for
_this_ you either need CT-scans to affirm through the lit, or
personal examination and knowledge of what you're looking for
[have to admit that the neurology of reptiles is not my
strongest subject, and I am quickly attempting to remedy that --
been spending more time working on mechanics and lines of force
to complete a preliminary set of studies on various things not
neurologically related fossil-wise].

<<*Bagaraatan* doesn't go anywhere in my phylogeny, because I
lack information. Segnosaurs... well, I've put them into
Sauropodomorpha with the usual arguments, but this placement has
become difficult to defend. Either way, one arrives at about 50
synapomorphies and 50 convergences, as someone stated onlist a
few years ago on this topic (now in www.dinosauria.com).>>

  Onlist a few years ago.... Search the archives for
*Beipiaosaurus *, please. Look at this taxon.

<<Sure?!? What are double-headed quadrates good for, anyway?>>

  A single-headed quadrate in all taxa that have it lack the
otic process and do not articulate with the lateral braincase,
but rather with the suspensorium (squamosal process of the
quadrate) as so are free to rotate on that head as a hinge; this
is further enhanced in birds and lacertilians by the lack of
contact between quadratojugal and quadrate, and only among birds
do the most primitive forms seem to still bear a contact
(ligamentous at that) to keep them together. Maniraptora have a
ligamentous contact here, but with two heads on the quadrate,
and it would appear that oviraptorids have added a secondary
contact (quadratojugal peduncle) on the quadrate to reduce this
condition. It is secondary in acquisition due to the absence of
the condition in more basal maniraptorans, or even segnosaurs.

<<Oviraptorids don't (secondarily?), but Caudipteryx has
something very much like one (maybe it really has one only 3
vertebrae long).>>

<Fine, don't believe the authors. Sure they're respectable
paleontologists, but that doesn't mean they're not blind (all
eight of them- Ji, Currie, Norell, Ji, Zhou, Wang, Zhang and
Xu). Caudipteryx does NOT have a pygostyle. Sure, the distal
caudals are stiffly held together, but it's the same in lots of
maniraptorans.>

  To back up Mickey's statement, there is no way the last caudal
in *Caudipteryx* functions as a pygostyle, as it is smaller than
the anterior element, and functionally separate as a series, not
as a unit, though is ossified as a "rod," and this suggests the
union is ligamentous.

<Microvenator is very odd in that its radius is very long
compared to its humerus (93%). This is even longer than
Sinornithosaurus (77%), Bambiraptor (65%) and Archaeopteryx
(84-88%). Only Jibeinia and ornithothoracines have such elongate
radii among theropods.>

  Not only does *Microvenator* have a funky arm.... :)

<Caenagnathus...>

Gripe here ... it's *Chirostenotes *.

<...is like some birds in that its surangular and articular are
fused. As both are labeled in the photos of Shuvuuia's skull
(Chiappe et al. 1998), perhaps they were unfused in
alvarezsaurids.>

Oviraptorids enjoyed fused postdentary mandibulae, too.

<<... like the ?nest-parasitizing *Velociraptor* chicks in the
oviraptorid nest)?>>

  Not a gripe, but a groan ... these skulls have been referred
to *Byronosaurus* in the recent JVP paper. As such, I restored
them together:

  http://www.geocities.com/Qilongia/Byronosaurus_with_chick.jpg

  Note, however, than the lower jaw was mistakenly restored
after *Sinornithoides* ... apologies, but I really liked the
picture and wouldn't leave it gathering dust. It's not hard to
fix, though. Ink medium.

  Mickey writes separately:

<<<proximodorsal ischial process>>>

<<I'll try to have a few looks at theropod pelves, about which I
don't really know much.>>

<The only non-pygostylians with the process are Bambiraptor,
Sinornithosaurus, Unenlagia, Rahonavis and Archaeopteryx. Well,
I suppose sinraptorids have a version of the process too, but
they're way down the tree.>

  You can add *Nomingia* and *Segnosaurus* (and possibly
*Nanshiungosaurus brevispinus*) to these.

=====
Jaime A. Headden

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

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