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Unwin's Cearadactylus



David ~ Thank you for sending your new paper on the systematics of
Cearadactylus. I read it immediately.

I send this letter to your personal mail box and to the dinolist, not
knowing if your Spaminator still has my email address targeted or not.
Please let me know if you would prefer future correspondence as emails,
rather than public posts.

In this paper and previous ones, you argued for a close relationship
between Cearadactylus atrox and Huanhepterus, Gnathosaurus,
Plataleorhynchus, Ctenochasma and Pterodaustro in order of increasing
distance. I note that your PAUP analysis employed 20 taxa and 67
characters.

The trouble is, even with a cladogram of 50 taxa and 160 characters, way
more than 80 percent of the characters turn out to be homoplastic. That
makes  listing a few pertinent characters almost fruitless because you
might pick the right ones and you might pick the wrong ones. Worse yet,
certain basal pterodactyloid nodes are separated from one another by at
most one or two steps - even with five distinct Pterodactylus species
for starters. One mistake or misjudgement and nodes start shifting. I
know from experience!

The firecrackers really started popping when I read your diagnosis for
the Ctenochasmatidae (Gnathosaurus, Pterodaustro, ca & ad (= common
ancestor and all descendants). abbreviated here. My mental queries
follow in parentheses.

1. rostrum ant. to NAOF more than half length of skull  (also in:
Pteranodon, Nyctosaurus, Quetzalcoatlus, and Diopecephalus)

2. anterior rostrum dorsoventrally compressed and rounded (actually your
fig. 1D looks pretty straight to me. I've seen a rounder (dorsal view)
rostrum in other anhanguerids. Plus, I wouldn't say "compressed " so
much as "excavated ventrally" to produce that maxillary "step" you
note.)

3. Seven or more pairs of teeth in the premaxilla. (I wish you had drawn
the premax-max suture. Or noted it on a photo. You left it blank. My
scan [attached to personal email] shows that, like all pterosaurs,
except for the real ctenochasmatidae, only four teeth appear in the
premaxilla of basal ornithocheirds ( or anhanguerids). Here the first
premaxillary teeth are gone so three are present. They are tiny in other
forms you are aware of, so it's no big loss. The suture is visible
between 3 and 4. )

You may have mistakenly assumed that the premaxilla began at the
beginning of the jawline "step." That's not true of Huanhepterus,
either, which also has only four premaxillary teeth and the rostrum is
neither compressed nor rounded, but "sags" ventrally at the tip.

My guess is that in the filter feeders like Ctenochasama, we're going to
find multiples of four feeth in the premaxilla as typically shed teeth
are retained.

4. Teeth project laterally...at least anteriorly. (also in: Dorygnathus,
Angustinaripterus, Haopterus and Diopecephalus).

5. Teeth in anterior dentition relatively elongate, with cylindrical
crown, tapering only at the distal tip (that's a very slight variation
on the above list, but perhaps worth noting).

6. Metatarsal III more than one third the length of the tibia (what
about nearly every long-tailed pterosaur, plus P. antiquus, and at least
one Germanodactylus?)

In my own analysis of all pterosaurs, unfortunately very few skull
characters turn out to be diagnostic within the limited clades you're
working with. At the familial level, the skulls are pretty conservative.

One that you mentioned, the greatest depth of the mandible occurring at
the symphysis, is also shared by such diverse taxa as P. antiquus,
Zhejiangopterus, Tapejara and Pteranodon. In fact it's the defining
character of that large clade. Tthe filter-feeders don't have it.

I can't agree with you on the low angle of the quadrate versus the
jawline, nor can I agree with you that the skull was probably lower than
others have reconstructed it. Dorsal to the NAOF is where the skull
profile typically begins to curve dorsally on anhanguerids.

In my data set, a deep jugal is homoplastic over eight separate taxa
going back to Austriadactylus, plus two more: the dsungaripteridae in
which the infilling comes in from the posterior of the orbit and
Pteranodon.

Again, thank you, David, for so promptly sending me this paper. It's a
valuable report on the history of Santana pterosaurs and brought to my
attention several important characters. The status of Cearadactylus,
according to my data which remains unshaken, is still close to
Anhanguera and kin.

With respect and fond wishes always,

David Peters
St. Louis