Re: Revising Hou et al, 96 (very very long)

["Jaime A. Headden" <qilongia@yahoo.com>]

I wrote:

<<Uhm, *Avimimus*? What lachrymal? The refered cranium PIN 3907/3 is so
well fused and defined it is not possible to determine a condition as to a
posterior lachrymal, if present at all.>>

and Mickey Mortimer (Mickey_Mortimer111@msn.com) wrote:

<The lacrimal in PIN 3907/1 of course, as described by Kurzanov (1981). 
The sutures are only "partially obliterated" and show a posterior lacrimal
process extending back to contact the postorbital.>

  Ack ... I looked at both the original paper, a photgraph of the
material, and the newer drawing in Kurzanov, 1987, and saw no such thing
applicable as a lachrymal that would fit your observation of an elongate
orbital process. What does seem present are the left parietal lacking the
posterior plateau, the left frontal, and portions of the prootic and
opisthotic (fused?) and laterosphenoid (Kurzanov's prootic), plus the
orbitosphenoid. The division of a rostral element along a smooth margin
rostral to Kurzanov's ID of a frontoparietal halfdome may in fact pertain
to a lachrymal, and in this suggestion, the preservation of the structure
is so poor that I find it hard to see how a posterior process at all can
be inferred to it. Otherwise, the nearly clean (though broken) division
between the halves of the domed element suggest that incomplete fusion of
the halves may indicate that the rostral element may in fact be the
frontal. A parietal longer than the frontal is not unexpected and is
present in some oviraptorids.

  Nonetheless, it is not clear that there is a posterior process of a
lachrymal at all. Kurzanov also identifies a postorbital element (po in
the figures); if this element is so, the rostral element _must_ be a
frontal by nature of it's position, and what Kurzanov identifies as the
orbitosphenoid is probably a fragment of the laterosphenoid. This permits
enough ambiguity in the holotype cranium that it cannot be used to support
the theory of a posterior, orbital lachrymal process.

  I also wrote on the orbital process:

<<The theory that the posterior process is apomorphic of the bone itself
or is 1) neomorphic, or 2) a fusion of the prefrontal to the lachrymal is
not resolved yet, though fossils indicate a T-shaped lachrymal element (or
lachrymal+prefrontal elemental fusion) as a Maniraptora synapomorphy).>>

  to which Mickey replied:

<It can't be just a fusion of the prefrontal, as many taxa with
prefrontals (including Sinornithosaurus) have the T-shaped lacrimal.>

  Yeah, and oviraptorids have very short posterior processes, as does
*Sinornithosaurus*, and this is permissible in a complex where the
troodontid-ornithomimosaur-dromaeosaur[oid] structure is dependant on
fusion. *Sinornithosaurus* is a basal animal; it may be expected to
exhibit lack of fusion, if at all present. Narrowing of the rostral
frontals may have precluded loss or marginalization of the prefrontal to
compensate for an increase in binocular vision. Oviraptorids show the
opposite: a short posterior process of the lachrymal, and broad rostral
frontals, and nearly a lack of binocular vision. The prefrontal may have
fused to the rostral frontals laterally. However, that the posterior
process is long[er] in dromaeosaurids and in birds than it is in
*Sinornithosaurus*, I can just as easily dismiss this _sans
considerationis functionalis_.

<We need a described quadrate to determine the state in Deinonychus, which
is not as Velociraptor-like as often said.  Indeed, Barsbold and Osmolska
(1999) say the paraquadratic foramen of Deinonychus was probably smaller
than Velociraptor.>

  We have a quadratojugal, and the length of the posterior process is
proportionate to the size of the foramen in *Dromaeosaurus* and
*Velociraptor*, and this is ample means to hypothesize the size of the
foramen in *Deinonychus*; personal observation tells me that the quadrate
foramen is as expansive in aspect in both caudal and lateral views, and
the ascending process is bowed rostrally and is well-forward of the
posterior third of the ventral length of the bone [quadratojugal] -- so
this would appear to indicate a definate large foramen. There is a good
deal of information on this, and there are several skulls that can be
referred to, including YPM 5210.

  [on elongated rostral chevron processes], Mickey also wrote:

<That are all also found in Rahonavis, a probable avialan.>

  Too a much smaller degree. But perhaps with the pedal morphology, this
is only a paravian/eumaniraptoran apomorphy, and non-illustrative to the
phylogeny of *Sinornithosaurus*. However, see below... 

  Mickey writes:

<Paul gives good support for Archaeopteryx's sickle claw in DA too.>

  My own examination of photographs does nothing to convince me of this,
nor does Paul's argument. The pedal claw does not appear to bear an
enlarged turbercle that separates it from the other toes, and the
phalanges do not appear to possess any production of a "heel." Paul
suggests that the first second digit phalanx possessed an extensive dorsal
articular condyle for the second phalanx, but I have failed and failed to
find any arc that was significantly indicative of extension of the toe.
 
<Byronosaurus, yes.  Sinovenator, Sinornithoides and Saurornithoides, no.
Struthiomimus and Dromiceiomimus, yes. Gallimimus, no. It's not
size-related, as Microraptor has the a deep premaxillary body.>

  This is interesting as I see the incomplete *Gallimimus* premaxillae as
being non-illustrative in this degree. True, in *Saurornithoides* the
premaxillary body is much shortened in lateral aspect, but this is partly
due to the medial curvature of the element as a result of the U-shaped tip
of the snout. The body is much longer when mesiodistal length is taken
into account. The premaxilla of *Sinornithoides* is evident in its length
because the snout is not U-shaped at the tip; similarly, the
*Byronosaurus* premax. The *Sinovenator* premaxilla is only twice as long
as deep. The *Microvenator* premaxilla is slightly longer.

<No data is irrelevent, most morphological synapomorphies are functional.
I'm sure dental characters are diet-related.  You don't see people
doubting the D-sectioned teeth of tyrannosaurids, despite the fact they
were convergent with Pelecanimimus, diet-related and functional.>

  Of course they were convergent. However, variability of serration
expression is much less diagnostic than tooth morphology as is presented
by the theropod record, and the occassion to reduce them in some paravians
(teeth of *Archaeopteryx* skulls have hardly been examined on this yet [or
anyway, presented on the matter]), *Caudipteryx*, compsognathids,
*Ornitholestes*, ornithomimosaurs, some troodontids ... it goes on.
Arguing the lack fo serrations as being diagnostic is just not feasible
given the record of variability. This is one of the reasons why I despise
the use of teeth by some researchers as a Rosetta Stone. Romer wrote of
mammalogists' use of teeth as landmarks in phylogeny, "teeth copulating
with teeth, to beget more teeth" ... the rest of the animal was
irrelevant. Not to say this is demonstrated in dinosaur paleontology, but
that it illustrates the poorness of relying on teeth-features to indicate
phylogeny without an extensive set of similarities or a complex not shared
by other animals which can contend for sister-group--hood.

<No, not in dromaeosaurids (Dromaeosaurus or Velociraptor) actually.>

  Actually, you are correct. Neither in *Deinonychus*, as well. I think I
was thinking of the wrong suspensorium in this context.
 
<There may indeed be a few oviraptorids without contact, but there are
others with contact.  Add Erlikosaurus and Caudipteryx, which both have
contact, and you get good evidence of convergence.>

  Good, Now dismiss *Sinornithosaurus* as the descending process of the
squamosal is robust enough to suggest that the too-short quadratojugal
ascending process is incomplete. And inconclusive.

  I wrote:

<<Not exactly ... *Sinornithosaurus* doesn't have that much in the way of
sterna.>>

  and Mickey wrote:

<O, not at all, with each sternal plate being longer than the sacrum and
supporting about five attachments for sternal ribs. ;-) What insignificant
sterna.....>

  Pity the hips are so small as to render the length comparison moot;
*Sinornithosaurus* and *Microraptor* all have very small hips compared to
the remainder of the trunk; conversely, as in pygostylians but not
*Archaeopteryx*, *Rahonavis* and *Unenlagia* have proportionately larger
hips, which may be illustrative of a trend towards birdy-style thighs. The
sternae are approximately half the length of the skull, similar to those
of *Velociraptor* (GI 100/25), if slightly longer. Again, this may be
plesiomorphic as the hypothesis of Paul (and corroborrated by Xu al.,
2002) is that loss of flight will result in smaller sternae for larger,
ex-flight animals. Look at ratites, for instance. And *Pelecanimimus* has
whoppers for sternals. Unfortunately, length of sternae are not the meter
by which sternal ribs are measured, or there would be plenty more on bird
sternae; instead, it is the count of sternal ribs, and only two have been
identified in hypothesis for the morphology as in *Velociraptor* and
*Citipati* sp. (GI 100/42), related to the lenth of the first lateral
process. Such facets in *Sinornithosaurus* may be restricted to the same
location, and to consider otherwise would require data I do not think we
have.

<It's thinner than Archaeopteryx, but does have the same morphology. Very
different from Velociraptor.>

  I disagree... the element in *Archaeopteryx* is very robust, and small,
whereas that in *Sinornithosaurus* is very wide, larger, and shallower in
angle; similar morphology, but with a hypocleidial projection, is noted in
*Velociraptor* and GI 100/42 (Barsbold, 1983; Norell, Clark, and Chiappe,
1995; Norell and Makovicky, 1997; Clark, Norell, and Chiappe, 1999).

<Which is why Compsognathus lacks it..... we all know how huge it was. 
;-)>

  Uh-huh ... one taxon and rhetoric.

<No, actually.  A third condyle for articulation with the mandible, like
some ornithurines.  Most theropods have only two, separated by the helical
groove.>

  I know of the condyle. I am aware of this and have looked at it in
regards to mandibular movement in birds. The apomorphy of a third condyle
is conditional to the extension of the lateral process of the mandibular
glenoid, and such a feature is easy to approximate in oviraptorid
quadrates and *Sinornithosaurus*. My contention, however, is that the
morphology I see in *Sinornithosaurus* is similar to that of oviraptorids
and does not form a third condyle. This would require mandibular
corroboration. *Microvenator* lacks such a condition on the mandible, it
appears.

<The distal end is lateromedially expanded, as in pygostylians.>

  The condyle, or the shaft? I see the element is rather flattened in
aspect, but this does not appear to be the same in pygostylians, which
expand the shaft proximal to the distal terminus (condyle).
*Archaeopteryx* lacks it, however, as does *Microvenator*.

<Of course it does Jaime, we believe you..... :-) Sinornithosaurus' pubis
expands very gradually towards the tip, then rounds off.>

  Please ... civility. The curvature of the shaft is what provokes the
phrase "J-shaped". As for the margin expansion, such is as much a pubic
boot as is that of troodontids.

  [on the proximoventral heel...]

<Like troodontids and Microraptor?>

  And a few other taxa, like the [possible basal maniraptoran]
*Ornitholestes*. *Rahonavis* has it, but *Archaeopteryx* does not. This
does not support a birds + Sinorn - dromies group, as I tried to say in my
last post at the end below this section.

  [on the raptorial claw]

<Like troodontids, Rahonavis and Microraptor?>

  As I said above, just cut and paste the entire paragraph ... though the
condition may be equivocal in *Ornitholestes*.

  [on the posterior metatarsal laminae]

<Like troodontids, Microraptor, Archaeopteryx and probably Rahonavis?>

  With my being able to view the posterior metatarsus, I can certainly say
that *Archaeopteryx* lacks this condition, and from what I've seen, so
does *Rahonavis*. This is quite conditional, but this may be one of the
basal deinonychosaurian synapomorphies, and Xu et al. touch on it as I
recall.

  Cheers,

=====
Jaime A. Headden

  Little steps are often the hardest to take.  We are too used to making leaps 
in the face of adversity, that a simple skip is so hard to do.  We should all 
learn to walk soft, walk small, see the world around us rather than zoom by it.

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