Jouve's and Tacquet's Ctenochasma sp.

[david peters <davidrpeters@earthlink.net>]

Stephane Jouvé asked that I post this letter to the dinosaur list.

With all honors, I do so now without comment, other two preliminary notes: 

1) a phylogenetic analysis of every decent specimen in the inventory of the 
Pterosauria reveals that that the Pterodactyloidea is paraphyletic, with 
separate origins for the Ctenochasmatoidea, etc. and the Azhdarchidae, etc. 
from various Dorygnathus specimens; and the Cycnorhamphidae + 
Ornithocheiridiade, etc. and Pterodactylidae + Germanodactylidae etc. etc. from 
various Scaphognathus (themselves derived from basal Dorygnathus). Thus 
comparing brain sizes in Pteranodon and Tapejara to Ctenochasma crosses many 
more taxon lines than comparisons to Dorygnathus (Parapsicephalus) purdoni and 
the micro ctenochasmatids.  The latest single tree can be seen at 

www. pterosaurinfo.com/familytree.html

And 2) questions regarding identification of bones need to go through two 
steps: labeling the specimen and creating a valid reconstruction. Problems 
arising with misidentification (and they are legion in the literature) usually 
can be discovered during the reconstruction process. And if I'm at fault here, 
then I'll make corrections. 

David Peters
St. Louis







Dear David,

 

Sorry for the delay of my reply, but I am very busy at the moment.

So, I provide some short comments to your comments below. I still disagree on 
all your comments and on your
 reconstruction, and I think many answer to your comments are in the paper.

I as very happy to discuss with you, and if you have other comments, no 
problems.

 

 

Have you seen the specimen ?

 

Stéphane.

 

Dear Stéphane,

 

Thank you for your reply. And again, congratulations on getting a paper

into JVP.

 

Please take the following notes and criticisms kindly. I have learned

much in my cladistic study of all the pterosaurs and not very much of

what I have learned is in the literature yet. So much of what you are

about to read will be new to this science.

 

In a strange twist, I have to retract part of what I mentioned in my

first email. Let me explain:

 

The Saint-Dizier specimen is a match for the skull crushed

dorsoventrally [PTHE 1951.84 (Mayr 1964, No. 70 of Wellnhofer 1970,

1991)] that has come to be considered the icon for Gnathosaurus-- and

not a match for  B St 1935 I 24, No. 65 of Wellnhofer 1970, Specimen 3

of Buisonjé 1981 the completely articulated specimen that has come to 

beknown as the icon for Ctenochasma.

 

But the Saint-Dizier specimen _does match_ the Ctenochasma holotype, a

large toothy mandible.

 

Remember, the mandible of Gnathosaurus (the holotype specimen) is not

spoon-billed either, just the rostrum is.

 

A reconstruction of the new Saint-Dizier specimen apppears at:

www.pterosaurinfo.com/saintd_gnathosaurus_recon.html

 

Characters in the Saint-Dizier specimen matching No. 70 and not 

Matching No. 65:

 

The antorbital fenestra is larger
 than the orbit.

 

Ontogenetic character !!!!!! n°65 is juvenile, and sof is larger than orbit 
too!!!

 

 

 The orientation of The jugal, (mislabeled quadratojugal) which cannot be 
compared to
 No. 70 is angled higher than in No. 65 and similar to more primitive taxa. The 
upper temporal arch is as high as the orbit, as opposed to No. 65, where it is 
considerably lower.

 

The quadratojugal is not misslabelled (see below). The upper temporal arch is 
also low here.....

 

 

The teeth may not be as robust as in the dorsoventrally crushed skull,

but another gnathosaurine, Plataleorhynchus, has even more gracile

teeth.

 

 

The teeth are much close from each other, much numerous (see Fig. 10), and much 
thinner and longer than in Gnathosaurus.

 

 

 

Note the broad nasals overlap the premaxilla dorsal to the antorbital

fenestra (mislabeled the premaxilla), as in all Ctenochasmatids. The

premaxilla is overlapped anteriorly by the maxilla, again as in all

Ctenochasmatids. The lacrimal is a broad plate (mislabeled the nasal),

so the mysterious nasal fenestra becomes the more typical lacrimal

fenestra.

 

 

Mislabeled premaxilla?????? Which figure???? In pterodactyloidea the 
premaxillae reach the level of the orbits.....I am not agree at all with your 
labelling of the skull bones....are we discussed on the same group?????

 

 

 

Some other labeling errors:

Fig. 1: The "prefrontal" is a part of the nasal. The real prefrontal is

over the orbit.

 

No, the lacrimal is clearly missing and covered laterally the nasal (present). 
Moreover, what you label nasal (I still thinking it is the prefrontal) does not 
reach the nasoantorbital fenestra (it reaches in pterodactyloidea).

 

 

Fig. 2: The right quadratojugal is the postorbital process of the
 

jugal.

 

 

No!!!!! The postorbital process of the jugal is located above the 
quadratojugal. There is a clear suture between the two bones!!!! Don?t forget 
it is an internal view.

 

 

The post orbital is too low in the tracing. The actual PO is just above

it.

 

??????? It is not a reconstruction of the skull but a draw of the specimen!! I 
drawn what I?ve seen, not
 what I should see!!

 

 

 

Fig. 4. The "brain" in the Saint-Dizier specimen is much too small. 

 

 

NO!! The brain is much smaller than the external bones of the skull (see 
text!!).

 

 

This needs to be reexamined. It cannot be compared to Pterandon and Tapejara 
which are not related, but must be compared to sister taxa, including 
Parapsicephalus and P.
 elegans.

 

Why can they not be compared to Pteranodon or Tapejara??? They are also 
Pterodactyloidea!!!! No ? P elegans is juvenile (see text) and Pareapsicephalus 
is not a pterodactyloidea (I am not sure on that). The condition of the skull 
in Pterodactyloidea is only known in Pteranodon and Tapejara (the true shape of 
brain!!)

 

 

Fig. 9. The uneven ventral margin of the dentary in a

specimen labeled, Pterodactylus "kochi" B St 1878 VI 1 [No. 13 of

Wellnhofer 1970] noted as an example of a fossilization artifact, is

not. an artifact. Instead this character is a genuine feature and the

genesis of the deep mandible found in some Nyctosaurus and Pteranodon, which 
are sister taxa. (See pterosaurinfo.com > taxa > family tree.

 

I completely desagree with that, and the mandibular shape in P. Kochi is 
clearly (for me) an fossilization artifact (see text). Moreover, in my 
phylogenetic analysis Pteranodon is far from P. Kochi...

 

 

You stated that P. antiquus [BSP Nr. AS I 739, No. 4 of Wellnhofer

1970] and P. kochi [B St ASXIX 3 (plate). SMF No. R 404 (counterplate).

No. 23 of Wellnhofer 1970] represent two different growth stages of

single species.  The
 holotypes of both can be found at

pterosaurinfo.com/p_antiquus_recon.html and pterosaurinfo.com/no23_recon.html 
for comparison. There's no 

comparison, although I would imagine that you did not consider the holotype of 
P.kochi, but rather the referred specimens of P. kochi, that we're all familiar 
with that are closer to No. 4. Stéphane, from now on, all pterosaur papers 
need to dispense with applied names, especially when dealing the 
ctenochasmatids and pterodactylids, because so many taxa are 

mislabeled.

Instead a more precise way to identify specimens is by specimen

inventory number.

 

C. porocristata or porocristatum is closer to

Huanhepterus and the azhdarchids in a paper coming soon.
 So it is

unrelated to Ctenochasma. See pterosaurinfo.com for a tracing and

reconstruction.

 

Argh!! In my phylogenetic analysis azhdarchids is far from Ctenochasma or 
Gnathosaurus and I?m still thinking that. 

 

 

The nomenclature problem that you have unintentionally unearthed is

interesting. Ctenochasma roemeri (Meyer 1852) is the holotype specimen.

As you noted, it is quite similar to the Saint-Dizier specimen.

Working backwards, that means that our traditional "Gnathosaurus" No.

70, may really be Ctenochasma. And our traditional Ctenochasma, No. 65,

may have to be renamed.

 

I still desagree with you on your taxonomic revision.

 

 

I know this means many changes in thinking. I've experienced the 

Changes during the last two years of my studies. It is hard to digest, I know.

 

 

I can digest much more than you seem to think....

 

 

 

 

Your critisism are interesting, but you seem to not take into account a lot of 
things. First: have you seen the specimen?? If you don?t, how can you provide a 
reconstruction???? I worked during one year on this secimen, and, if some 
points can be discussed, I still desagree with nearly all your comments.......

 

 

Please, can you provide this discussion on the dinosaur list? I?ve seen
 your comments on my paper, and I?d like my comments was on too.
(have you a problem with Chris Bennett ???? He only did some comments, mainly 
on taxonomical points, but this work is mine, even if I thank Dr. Bennett again 
for his constructive and argumented comments.
JOUVE Stéphane
Laboratoire de Paléontologie
8 rue Buffon
75005 Paris - France
01.40.79.33.52
e-mail:jouveste@mnhn.fr