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Re: what's wrong with Jouve's Ctenochasma?



> 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 be
> known as the icon for Ctenochasma.
>
> But the Saint-Dizier specimen _does match_ the Ctenochasma holotype, a
> large toothy mandible.

Fig. 10 shows that the ratio of tooth number to skull length is more similar
between *C. roemeri* and *Gnathosaurus* than between *C.* sp. and
*Gnathosaurus*. In fact, *C. roemeri* is about halfway between the other
two.
        But it is true that these three are more similar to each other than
to *C. elegans* in this respect (Fig. 7).

> The teeth may not be as robust as in the dorsoventrally crushed skull,
> but another gnathosaurine, Plataleorhynchus, has even more gracile
> teeth.

Unfortunately *P.* is not mentioned by Jouve.

> The lacrimal is a broad plate (mislabeled the nasal),
> so the mysterious nasal fenestra becomes the more typical lacrimal
> fenestra.

What mysterious nasal fenestra? Jouve always talks of a "nasoantorbital
[sic] fenestra", and it's in the expected position. But what, if anything,
is a "lacrimal fenestra"? The lacrimal duct???

> Some other labeling errors:
> Fig. 1: The "prefrontal" is a part of the nasal. The real prefrontal is
> over the orbit.

Probable... from my dinosaurocentric point of view.

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

I'd say... judging from its position, if it isn't a quadratojugal, then it's
a quadrate. A postorbital process of what ought to be the jugal, and is
labeled as such, is present above the qj.

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

No. Look where the two temporal fenestrae are.

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

Why do you simply state this as a matter of fact, even though Jouve makes
quite clear why he disagrees? Why should the brain, for example, keep the
same relative size as in the baby called "*Pterodactylus elegans*" (Fig.
4B)? Why shouldn't it be as small as in *Tapejara* and *Pteranodon*?

> Fig. 9. Jouve points to the uneven ventral margin of the dentary in a
> specimen labeled, Pterodactylus "kochi" B St 1878 VI 1 [No. 13 of
> Wellnhofer 1970] as an example of a fossilization artifact, but it is
> not. Instead this character is a genuine feature and the genesis of the
> deep mandible found in some Nyctosaurus and Pteranodon.

Why do you simply state this as a matter of fact, even though Jouve gives a
quite plausible explanation for why he thinks it's just squished?

> Jouve states 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

dentary looks squished

> and pterosaurinfo.com/no23_recon.html for comparison.

What have you done to its vertebral column? -- Other than that, it looks
juvenile. Short neck, short snout and all.

> There's no comparison,
> although I would imagine that Jouve is not considering the holotype, but
> rather the referred specimens of P. kochi, that we're all familiar with
> that are closer to No. 4.

When looking for No. 4, I learned that this is the holotype of *P.
antiquus*... and found this
http://www.pterosaurinfo.com/p_antiquus_rostrum.html. It is dead obvious
that the multiple nares are neurovascular foramina and/or breakages -- 
that's why they look so irregular.

> C. porocristata or porocristatum will turn out to be closer to
> Huanhepterus and the azhdarchids in a paper coming soon. So it is
> unrelated to Ctenochasma.

Then why is its skull absolutely identical to those of other *C. elegans*,
apart from ontogenetic features?

> Dr. Christopher Bennett is acknowledged  for "numerous suggestions,
> comments and criticisms [which] improved this work significantly."

Er... and?

> The nomenclature problem which Jouve has unintentionally unearthed is
> interesting. Ctenochasma roemeri (Meyer 1852) is the holotype specimen.
> As Jouve 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.

This looks possible, although it's just a splitter vs lumper problem at the
moment.