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Re: Let's find the basal Ornithodire - part 1



MAJOR appologies for the two posts, I have split this into to pieces as a
result:

Dave Peters (davidrpeters@earthlink.net) wrote:

<DP: It's unprepared. A split slab only.>

  If Dave then agrees this is an unprepared slab, how can he find even the
most minutely, grin-sized structures to be preserved as impressions ON TOP
of the slab, on irregular, broken-edged surfaces?

<DP: 2 reasons: 1) why raise your hand, if your're a professional, and say
you see something that only an amateur nutcase has seen.>

  I have NEVER called Dave an amateur nutcase. That has always been
someone else. As I have stated before, I hold a lot of respect for Dave
for THIS very reason, for determined thouroughness to his theories, though
for a scientist this may be a liability: once one believes hardf enough,
very little can sway it, as one sees with dogged believers in OTHER,
unmentioned fields. I have NOT approximated Dave with this subject
however, only warned that abject support is a tricky, tricky thing in
science since anything based on it, like the forensic issue of discovery
requiring _sound_ precipitating factors: in a court, for example, you need
to show you had the RIGHT to search a vehicle before you can use any
result of that search for evideniary purposes -- thus any actions based on
an "illegal" search are unuseable. In science, it is much the same: one's
data is based on the method used to collect it, and if no one else can see
this data, the doubt of the veracity of the results become even weaker. I
am arguing for more ... veracity ... in this field, rather than calling
ANYONE a nutcase. And given how many people publicly disavow me in OTHER
forums, I can a few people I CAN call such, yet never do for reasons of
respect and integrity. Thus, to you Dave, I do NOT consider you to be a
nutcase. And I, myself, am also an amateur, though I should be in school
at Portland State within the next few months ... it will be many years
before I can call myself a "professional."

<At present professionals are not even _testing_ or _trashing_ my 2000
cladogram based on all previous cladograms and easily visible materials
and the literature. They're avoiding it. Why? Professional issues? It's
the strangest thing.>

  When this analysis came out, it was not based on new discoveries of
impressioned organisms and their use in a cladogram. In my opinion, the
prolacertiform theory has become a leading, if not THE leading contender
for pterosaur relationships. To my knowledge, the prolacteriform theory
has only been marginally tested and this was PRIOR to your work by Benton,
and subsequently not to the result of testing it. However, NO one has
formulated such a study to test BOTH using similar, if not THE same data
set, for dinosaurian and prolacertiform relationships. Sometimes, these
things take TIME, and the lack of a detailed study, in print at least,
does not mean professionals are NOT doing this.

<2) these images can only be seen _after_ they have been traced. They are
_that_ ephemeral. That's why so many things have been overlooked.>

  And that's been my point. It's not about being ephemeral, as in _camera
lucida_ drawings of Chengjiang organisms the features depicted are usually
visible to the nake eye nearly as clearly as to the lucid drawing. It's a
matter of the tracing being the origin of the work, not what is available
to the fossil. I say, before publishing further on this, use a MICROSCOPE
and examine the material first hand, as much as you can. If they can be
traced, they would be there if you get down to the nitty gritty. Bennett
has already publicly remarked on the use of photos and their graininess,
as unreliable tools for this purpose. I would have hoped this would have
permitted what I feel is more thouroughness and "professional" regard to
the hypothesis, being a professional or not.

<You need to see the real thing. Not a cast. As an aside, I found the
ascending process of the premaxilla, the complete left palate and the
occiput of Longisquama the fiftieth time I looked at the specimen. Why?
Because I didn't recognize these parts for what they were.>

  I never stated my observation disproved by the type. The cast itself
preserved the massively irregular lower corner of the slab, and photos
confirm that entire sections of it are missing. Instead of showing
elements trailing off the broken slab, Dave "found" EVERY SINGLE element
of the skeleton in a bizarre twist. If the wrist ends at the margin of the
slab, the manus is off to the side, as in *Longisquama.* This is highly
unlikely.

<The same thing occurs in other ephemeral images. The same mental process
occurred in the discovery of theropod clavicles.>

  The identifcation of theropod clavicles (instead of interclavicles) and
the comparison to furculae were based on testable hypotheses that have yet
to be refuted, but have in fact been continually tested by repeated
identification and preservation in the same place. Identification as fused
clavicles has been enforced largely by the presence of identical
condensation in birds. Dave's ephemeral identifications have NOT the same
supportive material, as only one person has found this material to date,
and others who have looked have NOT found NEARLY the volume of material.

  For example, I examined the very same photos Dave used to illustrate the
expansive "frills" of *Sharivopteryx,* and am impressed that Dave has not
apparently taken into account the nature of prepared surface areas in some
of these fossils, this especially, or the nature of some material NOT to
provide viable sediment for impressions, as in chalk (for the KJ1 and KJ2
*Nyctosaurus* sp. material).

<Some things you don't recognize until you have your ephiphany.>

  G. S. Paul had an epiphany once, when he first described *Ornitholestes*
with a nasal horn. As will be shown very soon (early next year by press)
but mentioned onlist, the premaxilla-nasal contact is absent, and the
so-called evidence for this horn was a broken, slightly eroded upraised
rostral narial process (supranarial bar). Osborn gave *Oviraptor* a nasal
horn for what is actually a slender splint of bone set in a poorly
prepared lumb of sandstone. These issues have now been rectified, and
identification of preservation artifacts have been and continue to be a
correcting issue in fossil description.

<Everyone thought Jeholopterus had a half of a skull. Everyone thought No.
9 was a juvenile. Etc. etc.>

  Examples of erroneous ID's occur all the time. However, some of Dave's
ID's have been based ON this contested method (No. 9 as a juvenile, well,
it CAN'T be, since pterosaur juveniles don't have calcified bones!) and
this presents these identifications in even more dubious consideration
than others that are questioned. This method has even resulted in
taxonomy, showing that it really MUST be proven, and not by repeated
application by ONE person, but use by other people on the same material to
provide corroborative data. This has been shown to result in a refutation
of Dave's method.

<The sternal elements are presented in full view ventrally. Sharov
illustrated them as such. I followed. Let me know specifically what you're
not seeing that has been reported in the literature.>

  The slab showes the U-shaped clavicular or interclavicular structure,
with a depressed region on the midline implying two unified elements, not
one. Below this is an irregular nearly trapezoidal structure that is
apparently continuous with an element, almost semi-circular in shape,
proximal to the humerus (and so suggestive of being a portion of the
scapulocoracoid structure. The irregular shape below the "clavicles" may
be interpretable as the scapulocoracoid OR the "sternal" elements, but
there is a measure of ambiguity in WHAT these are unless one assumes they
must represent a scapulocoracoid, OR a sternal complex, OR both, and thus
one SEES divisions (as in the "manus" of *Sharovipteryx,* complete with
distal phalanges bearing lateral ligament pits illustrated by dots and
curves, which are entirely absent in the corresponding photo) where
another would not, but see a crack, or the other element in a pair, etc..
Thus I disagree with a sternal complex as illustrated, and how it is
impossible for me anyway to agree with Dave on keels or Sharov AND Dave on
the finesse to which the shoulder is illustrated.

<DP: Well, I think you're agreeing with me, Jaime, because the keel is the
interclavicle.>

  The presence of an interclavicle does NOT provide evidence it was a
keel. A keel by use (say, in crocodylomorphan scutes, *Protoavis*'
"sternum," birds, or even bat sterna) forms from a lamine of bone on the
midline or a "puptent" structure with a lamina in one direction at least.
Such a structure is NOT apparent on the slab beyond any ambiguity. I think
it's application as a keel has come from the hypothesis, also untested,
that the interclavicle forms the anterior ramus of the pterosaurian
sternum and thus the keel below it or arising from it derives from the
interclavicle. This does not show a keel in *Longisquama.

<And in Cosesaurus the exposure is ventral, so the keel won't be obscured
beneath anything.>

  I will give this to Dave for now. My photo of the slab, from Dave's
site, does not show a clear identification of the vertebral series over
the pectoral region, though I can see to some degree vertebral margins in
portions of it. It is entirely possible elements of the ribs and shoulder
apparatus overlay or interlay one another in a mass, ventral or dorsal. I
still do not see a clear shoulder region, just as personal examiners
haven't been able to see clear details in the skull.

<DP: Peters 2000 counted extra sacrals in Cosesaurus. There's no doubt of
extra sacrals in Sharovipteryx. There are seven vertebrae between the
extended ilia in MPUM 6009, the basalmost pterosaur.>

  The material shows that the preserved pelvic fragments cross at most TWO
vertebrae, not seven. I do not agree with Dave that elongated cranial
processes of the ilia exist. Even should such iliac expansions exist,
anterior caudals are incorporated between the posterior ilia in dinosaurs,
as are posterior dorsals, without being incorporated into sacra. This is
true to some degree in pterosaurs as well. Counting vertebrae between ilia
DOES NOT correspond to sacral vertebral count.

  Question to Dave: Do you assume that basal pterosaurs also had seven
sacrals?

<I cannot help you find what you're looking for. I haven't studied
problems related to spinal flexion in this clade. I can tell you that in
basal pterosaurs the spine is relatively short, as in immature Longisquama
and as opposed to adult Longisquama.>

  And as I content, the dorsal series in *Longisquama* is not complete.
The dorsal series is far longer than the cervical, at times the length of
the skull or longer, so I consider this refutation inadequate to my
contention a rigid spine or evidence of such rigidifying features has yet
to be recovered in prolacertiforms.

<You're using apriori assumptions. Again, long antebrachia are one of the
synapomorphies of the Pterosauria. Non- and pre- pterosaurs won't have
them.>

  Yes. In my defense, I content the a priori assumption of long arms
preceeding flight ability to be both testable, and at the time, the more
likely assumption. In both insects and birds, elongation of the flight
structures MUST have preceeded their use as lift-producing devices. Ken
Dial tested this by using variously clipped-winged chukar partridges and
their effective use in lift. An animal cannot fly with its wings being too
small to produce lift, so in the fossil record, an animal MUST have
existed that did not fly, had long arms, and was NOT a pterosaur, unless
the condition of arm elongation occured WITHIN the clade to which the name
Pterosauria will be fixed (which, to my knowledge, is very ambiguous).

<I hear what you're saying, but I'm saying they remain separated and
identifiable on the surface. Perhaps on the internal surfaces they are
joined in basal forms. I'll grant you that. Remember, some things like
tail vanes and syncarpals do show up later in pterosaurs, not in basal
forms.>

  Once again, "locking" and "closure of sutures" I contend are different,
as in my example of trends towards pterodactyloids. I made the
consideration before. I see the trend in the following:

  1. separation of elements as distinct from one another, with clear space
     between them, as in some aquatic reptiles, say *Dinocephalosaurus* as
     preserved.
  2. close association of elements, elements will often have contacts with
     multiple elements and show apophyseal surfaces for contact.
  3. elements are "married" or "locked" to one another, where their mutual
     contacts are integrated, as in astragalar/calcaneal elements in
     terrestrial amniotes, and association between the distal carpals in
     coelurosaurian birds, and the carpals of basal pterosaurs.
  4. sutures exist and elements become partially fused, as in the distal
     carpus of *Heyuannia,* and even the neurocentral sutures of most
     vertebrates
  5. sutures are obliterated, elements become so firmly fused that margins
     are not apparent at all, as in pterodactyloids, the carpometacarpus
in
     birds, tarsometatarsi in birds and pterosaurs, etc.

  I hope this helps.

  ... to be continued ...

  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.

"Innocent, unbiased observation is a myth." --- P.B. Medawar (1969)


                
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