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Re: comments on KJ1 and KJ2



----- Original Message -----
From: "David Peters" <davidrpeters@earthlink.net>
To: "dinosaur list" <dinosaur@usc.edu>; "Chris Bennett"
<cbennett@bridgeport.edu>
Sent: Sunday, June 29, 2003 9:25 AM
Subject: comments on KJ1 and KJ2


> Thanks to former dinolister, Tracy Ford, a photocopy of Chris Bennett's
> 'New crested specimens of the Late Cretaceous pterosaur Nyctosaurus'
> Paläontologische Zeitschrift 77(1) 61-75, 2003 fell into my paws.
>
> Fascinating animals. Would love to see what the smoke trails in a
> wind-tunnel would do with a model of either one. The descriptions were
> fantastic.

I hope that last sentence is a compliment.

> The illustrations continued, unfortunately, a pterosaur
> ptradition of small-scale outlines, rather than detailed illuminations,
> especially of the skulls and pelvis. Hopefully that will change someday.
>
> Just a few questions:
>
> 1. Was wondering why the long straight structures associated with the
> metacarpal IVs are identified as ossified tendons rather than vestigial
> metacarpal I-IIIs.
>

Perhaps you should wait for my thorough redescription of the osteology of
Nyctosaurus presented in progress.  The Pal. Z. paper was simply meant to
get the two crested specimens in the possession of the private collector
published.


> 2. Was wondering how FHSM [= SMM] 11311 fit into the clade, especially
> considering the bump on the rostrum that looks like a  solidified
> version of the premax crest on a germanodactylid.
>

The bump on the nose of the Fort Hays specimen resulted from a combination
of postmortem damage to the skull and inaccurate reconstruction.  It is not
a crest.


> 3. The hypothesis of crests appearing only at some level of maturity
> makes me wonder about the baby/immature Tupuxuara skull I saw in Tucson
> some years back that sported a large if immaturely rounded crest -- and
> Pterorhynchus, which has an unfused scapula/coracoid and a large soft
> crest. Perhaps the crest/crestless forms of Nyctosaurus should be
> considered separate species? IMHO the different morphologies of the
> skulls and mandibles may also lead in this direction.
>

I discussed the significance of the presence and absence of the crest in the
Pal. Z. paper.  Perhaps you should wait for my taxonomic revision of
Nyctosaurus.  What different morphologies of the skulls and different
morphologies of the mandibles are you referring to?  Can't you see the
forest?


> 4. I'm interested in Chris's comment that the scapulae in nyctosaurs
> were expanded medially [and were obviously rotated laterally], but did
> not articulate with the notarium. How does this work?
>

Just fine, thank you.  The presence of specimens of Nyctosaurus over several
millions of years well out in the Western Interior Seaway indicates that
their pectoral girdle and its associated musculature functioned perfectly.
But seriously, one might view the pectoral girdle of Nyctosaurus as either
an incomplete stage in the ontogeny of an advanced pectoral girdle complex
in which the scapula articulated with a notarium or as an incomplete stage
in the evolution of an advanced girdle complex.  I favor the latter
interpretation because there are mature specimens of Nyctosaurus that lack
an articulation between the scapula and notarium.  As for the functional
significance of the girdle morphology I suggest you see my paper
"Morphological Evolution of the Pectoral Girdle of Pterosaurs:  Myology and
Function" in the upcoming volume "Evolution and Palaeobiology of Pterosaurs"
edited by Buffetaut and Mazin.


> 5. Does the addition of a crest, at least for some nyctosaurs, move it
> any closer, phylgenetically, to the clade that also includes Pteranodon?
> The rising posterior premaxilla along the anterior rim of a tall crest
> is also shared by P. sternbergi.
>

The closeness, or lack thereof, of the relationship between Nyctosaurus and
Pteranodon is a historical fact.  The new information that Nyctosaurus had a
cranial crest does not affect that fact, though it may well affect our
attempts at reconstructing the phylogeny of pterosaurs.  Comparison of the
cladistic analyses by Unwin, Kellner, and myself indicates that there is
considerable homoplasy within the pterodactyloids, and suggests that we
should be careful in choosing the characters we use.  As for the
significance of the presence of the crest, if you have been following my
recent publications you would know that I am of the opinion that all
pterodactyloids possessed cranial crests, and therefore the fact that we now
know that Nyctosaurus indeed possessed a crest tells us nothing about the
closeness of its relationship to Pteranodon.

David then followed up with one last question:


----- Original Message -----
From: "David Peters" <davidrpeters@earthlink.net>
To: "dinosaur list" <dinosaur@usc.edu>; "Chris Bennett"
<cbennett@bridgeport.edu>
Sent: Sunday, June 29, 2003 12:36 PM
Subject: .and one last question on KJ1


> _Anterior_ to the crest and rising to the level of the posterior ramus
> of your new Nyctosaurus is some sort of discolored matrix material that
> might remind one of soft crest material, ala Tapejara, Germanodactylus,
> Pterorhynchus, etc.
>
> Chris, if you covered that discolored patch in your paper, I missed it.
> If not, any thoughts?
>

I clearly stated in the caption of Figure 1 that the chalk of the slab had
been painted off-white.  As a result, the actual chalk is obscured except in
some very narrow bands immediately adjacent to the bones, and the discolored
area is discolored paint.  Just as sometimes a cigar is just a cigar,
sometimes a discoloration is just a discoloration.

Chris


S. Christopher Bennett, Ph.D.
Assistant Professor of Basic Sciences
College of Chiropractic
University of Bridgeport
Bridgeport, CT  06601