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Re: Jaime's reply - parts 1 and 2 (medium short))
Dave Peters (firstname.lastname@example.org) wrote:
<Bennett's remarks would have had more of an impact if I felt there was an
iota of validity to them. Or if there was a discussion rather than a
Does this not sound like politics? Are we to weigh people's information
based on our personal feelings? I think more than a few people gained
something from that discussion, including the issue of how far one can
trust pixels on the screen to represent artifacts ON THE SLAB.
<As I reported then and do so again, those bumps were parts of larger
objects which I did draw and was able to identify and he, to this day, has
And, this makes him wrong? He didn't find a few bumps ... he didn't find
"ephemeral" structures? Does this not have the same flavor? Does NOT mean
he (or you, for that matter) is wrong, but it was a scientific approach.
Other's have also tested the tracings of pixellated images, and have NOT
yet achieved resolution.
As an example: in the new paper on *Dinocephalosaurus,* the authors
include a nicely detailed photo of the specimen. To view a single cervical
vertebra (the 7th, I think) at full screen size, one looses virtually ALL
useability of the image, as each individual pixel of the digital image
approaches a square centimeter in size. If we were to use this as a source
of information, what reliability would be given to any tracing? Take any
digitized photo with the same grain of salt, methinks.
<The point of using photographs is to see ALOT of specimens, a necessity
when working up a cladogram. All I can say is, I learned alot that had not
been known before. And it is internally consistent.>
Yes, about that consistency. Once one "knows" what to look for, it
becomes a matter of course to "find" it. One gains an a priori idea that
these structures, as most every skeletal, element must exist. Take an
example from Peters' *Eosipterus* in which the entire skull overlies a
slab that, from a tracing, there is such poor lighting it is hardly
possible to see the bony elements that the originating authors identified
by camera obscura. The same issue of identifying elements occurs in the
dinosaur *Cryptovolans,* in which the published photos are so dark any
id's become ... questionable.
As I will repeat below, such cases become issues where seeing the
specimens in person are IMPERATIVE. Should I rely on the mounted skeleton
of *Baryonyx* to restore a skeletal reconstruction? Or should I use photos
and illustrations of the ORIGINAL MATERIAL? Preparation artifacts (as I
state on some specimens, including *Sharovipteryx*, may obscure and
confuse researchers) are just as misleading if all one has is a photo.
<Show me what you mean. Something is not clicking here.>
I will work to prepare a "tracing" using my key structure for fractures,
<Actually, it might. Think about where those unossified transverse
processes are going. And don't restrict yourself to only fused sacrals,
because some pteros have no fusion in the sacrum at all.>
I would like to clarify what a sacral vertebra is. Since the time of
Romer, and a little before (I don't recall who actually "set the record
clear" on it), sacrals have been identified in those vertebrae for which
the transverse processes contact the centrum, or incorporate the sacral
ribs, usually fused, which contact the centrum; such vertebrae have
processes that contact the ilium, or the vertebrae are fused to such
vertebrae. *Herrerasaurus*, a basal dinosaur, has TWO sacrals that contact
the ilia, but has three fused sacrals, including a sacrocaudal vertebra,
which does not contact the ilia. To prove sacrum count, one should
invariably use several criteria:
1. Number of fused sacral centra. One must prove fusion. In
*Cosesaurus,* this is NOT clear at all, based on the resolution of the
photo and of the preservation from this source.
2. Contact of transverse processes and/or sacral ribs to the ilia. As
Dave notes, this does NOT occur in *Cosesaurus* for all vertebrae he
states belong to the sacrum.
3. Impressions on the ilia for contact of the sacral transverse
processes and/or sacral ribs. This most CERTAINLY is not discernible in
4. Fusion of the sacral neural arches, or the formation of a "neural
lamina" in which the spinous processes become conjoined, as in a "blade."
This is NOT apparent in *Cosesaurus,* wether the vertebrae were dorsal or
ventral in view.
<My cladogram only goes to "more than five." Seven does not seem
unreasonable considering the greatly elongated ilial processes in basal
Interesting. I say that because this bears much introspection. Frogs,
like pterosaurs, have extremely elongated ilia, yet have only one sacral.
So even were anyone able to PROVE that non-pterosaur prolacertiforms or
protorosaurs were to have such processes of the ilia (pointless in an
aquatic animal, where minimalization is the key), this STILL does not
prove that such sacral counts are real, only imagined, by token the
hypothesis of ilium length corresponding to sacrum length (which I show
above and previously) to be false. Indeed, even in extant birds, the ilia
encompass the first few anterior free caudal vertebrae as well as the last
1-2 dorsal vertebrae, however locked they may be, none of which show
_fusion_ nor do they contact the ilia, thus not being sacrals in any way,
shape, or form.
<DP: When one is found, I will buy your beer for a year.>
Make that Diet Coke, I'm hypoglyceimic :)
<The next paper has it.>
I look forward to this eagerly. Would it be amiss to request a free copy
when it's made available?
<DP: My mistake. I took from your comments that you had already created
the tracings from whatever you had available. I'm happy to see that you
have at least tried the technique. I wouldnot be disappointed if things
are still overlooked or overcooked. I'm reviewing my own work constantly
as errors appear to show up. All part of the sanding and polishing
<I used 182 not so carefully chosen characters (most have nothing to do
with flight) and I can tell you how many characters are shared by
Sharovipteryx or Longisquama and MPUM 6009: 160. That's 88 percent. Among
the 22 characters not shared: 4 are crest related (Longisquama has a crest
to support that headdress). 12 are wing related. The others are scattered.
4 in the skull. One in the coracoid. One in the femoral head where in
MPUM 6009 it is inturned, but without a contricted "neck". Hard to tell in
Longisquama. This character might drop off the short list some day.>
Using my observation of the slab, I can already throw out the frill
characters as I cannot see any evidence for them and therefore cannot
verify [the count would stand at 156 = ~86%); *Longisquama* (or indeed any
prolacertiform/protorosaur) has no wing, so I assume this refers to the
arm. *Longisquama* as well as *Sharovipteryx* lack constricted necks in
their femoral capiti (well, rather, I can't say this: *Longisquama* lacks
a femur and preservation of the proximal femora and ilia overlying them
suggests, but does not show), but then, some bona fide lizards _have_
them, and in the advent to a leg capable of "swinging backwards," or the
ability to sprawl, such a femoral adaptation would be beneficial, as it
would then be selected for. Read the arguments on why this is less likely
to be a "clean signal" with regards to bird evolution in my refutation of
Paul's sprawing microraptors theory (note that Xu et al. propose a
_different_ mechanism of leg deployment in a wing for the microraptors in
his SVP abstract) [155 = 85%]. I cannot see a coracoid in any clear detail
given the possibility of the sternal complex inferred by the
"interclavicles," so I will make this ambiguous [153 = 84%]. What arm
As for my characters that I described earlier, these were features that
relate to the advent of flight found in pterosaurs NOT found in
prolacertiforms, thus expected to appear in series towards the evolution
of pterosaurs. It was NOT intended to support an ornithodiran origin, for
even if they were ornithodiran, it would only show that birds and
pterosaurs were CONVERGENT. As I noted, it takes "ephemeral" features to
find pterosaur-like anatomy in the relationship to flight, including
sternae, elongate iliac cranial processes, etc., in non-pterosaurs. This
is what I was arguing against.
<You missed my point. The result they wanted to get, I can double-dog
guarantee you, is a single tree. Unwin got 6 trees. Kellner: 80.>
I've already disagreed with dave on this elsewhere, and agree with
Marjanovic on the matter of a fractal geometry when it comes to tree
building. The case is not very clear in my opinion.
<Universally accepted is a red flag, in my opinion. I've seen worse case
scenarios. Here's an idea: leave room for doubt!>
And yet we test. Even then, "universally accepted" is the first reason I
investigate a theory, because it stands to reason people may blind
themselves. Well, when it comes to something that requires less than logic
to determine. Ontogeny in salamanders, primates, birds, snakes, lizards,
crocs, etc., show that many features that should appear in embryos are
ignored in Dave's studies of pterosaur slabs for the sake of ephemeral
<DP: Why didn't you just say insects? The kind with larvae. I know you're
trying to be good lawyer and argue only for one side, but try to avoid
exceptions and examples that come from far afield and stay with creatures
that look and act like the subjects at hand.>
Ah, but insect larvae are more so alike than their pupae and adults than
you'd imagine, proving my case if I were to start listing characters. Take
moth and butterfly larvae (aka, caterpillars), or ant and bee larvae
together, the maggots of wildly different flies, and so forth. A phylogeny
of larvae may, hypothetically, yield a similar tree, but I assure you he
characters "findable" would so SO far fewer than when included in the
adult tree, they will SCREW the situation up, and my point is made for me.
Fish larvae and fry are even more similar, using basal vertebrates as
another example. Tuna fry look like eels, but are they? No.
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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