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Czerkas Book - the pterosaurs



Back on September 30 (seems ages ago now!), Mickey Mortimer gave a synopsis
and comment on each paper within the Czerkas book, and at the end of the
comment on the first pterosaur paper wrote:

>  I'd like to see what Unwin, Bennett, Peters and such would think of this
specimen
> and the next.

Well, I would like to tell you what I think of the pterosaur papers but my
daddy always told me not to use those kind of words and my mama used to say
"if you don't have anything nice to say, don't say anything at all."

But seriously, I can comment on the specimens and content of the papers.
Plenty has already been written about the quality of the writing, and I need
not add anything, but I cannot help but note that I found the writing
extremely irritating.  I wanted to grab my pen and insert commas, correct
the spelling errors, cross out words, and write marginal comments to the
authors.  Both pterosaur papers list an anonymous reviewer and I can assure
you all it was not me--those who have had the misfortune to have me review a
manuscript of theirs know that I always sign my reviews.  By the way, please
forgive me if I make an observation that has already appeared in one of the
Czerkas book threads.  I read the early messages in the threads, but
recently I haven't been paying really close attention because some of the
arguing on the dinolist gets really tiresome.

Anyway, the papers clearly demonstrated that the authors were not familiar
with the pertinent literature pertaining to rhamphorhynchoid
pterosaurs--quite a number of papers that I would think should have been
cited and discussed were not mentioned at all.  In addition, the authors
seem to be largely unfamiliar with pterosaurian osteology.


Comments on "The first occurrence of skeletal pterosaur remains in Utah" by
Czerkas and Mickelson.

To begin with, it may be the first description of a pterosaur from Utah to
be published, but it is not the first specimen.  I have better preserved
pterosaur remains from Utah plus a half finished manuscript on them in my
specimen cabinet, but other things have been higher priority...so many
fossils, so little time!

One problem is that Czerkas and Mickelson do not present any characters that
diagnose the species, so it clearly is a nomen dubium, and I suspect that
most academic paleontologists would not have named a species.  Certainly, I
wouldn't have.

More importantly, the authors do not present any characters to support a
pterosaurian interpretation of the specimen though they suggest (p. 6) that
the scapulocoracoid "clearly indicated that the specimen was of a flying
nature."  The scapulocoracoid does not look like a typical rhamphorhynchoid
scapulocoracoid to me.  They suggest that the presence of elongate
prezygapophyses indicates that the specimen is a rhamphorhynchoid, but the
elements described as "ossified 'tendons'" in Figs. 6 and 7 are relatively
coarser than the elongate zygapophyses seen in Rhamphorhynchus and similar
taxa, and there is no evidence of the bundled multiple zygapophyses that one
would expect from a typical Lower Jurassic rhamphorhynchoid [see for example
Fig. 21 in the next paper on p. 31 for an illustration of the tail of a
rhamphorhynchoid pterosaur].  If the animal was a Lower Jurassic
rhamphorhynchoid, then it was a giant: if I have correctly interpreted the
scale bars, then the incomplete caudal vertebra in Figs. 6 and 7 seems to be
over 2.5 cm long, the dorsals are 11 mm long, etc.  I very much doubt that
the specimen is a pterosaur; the authors have not described any features
that support a pterosaurian interpretation, I cannot see any such features
in the figures, and the quality of the bone does not look like what I have
come to expect from pterosaurs.  Do not misunderstand me, I'd would be quite
pleased if this turned out to be an aberrant giant pterosaur from the
Morrison, it's just that as far as I can tell from the Czerkas and Mickelson
paper, this isn't a pterosaur at all.


Comments on "A new rhamphorhynchoid with a headcrest and complex
integumentary structures" by Czerkas and Ji.

This is an absolutely fabulous specimen.  Unfortunately, the authors
essentially do not describe the osteology of the specimen, and I cannot
reconcile their reconstruction of the skull in Fig. 5 with the illustrations
of the skull in Figs. 3, 4, 6-8.  Most of the description is of the
integumentary structures.  I cannot determine exactly where some of the
close-ups (e.g., Figs. 22 and 23) are on the specimen, and the orientation
of the close-ups is also not clear.  It is clear to me that the close-ups
show filamentous integumentary structures, but I am not convinced by the
interpretation presented by Czerkas and Ji.  I think other interpretations
are plausible possible, but the discussion does not mention alternative
interpretations.  There is a lot written about the implications of Czerkas'
and Ji's interpretation of the integumentary structures, but I see no point
in worrying about that until the nature of the structures is better
understood.

Lastly, I'm no paleobotanist, but isn't the thing that is described as "Tip
of wing showing aktinofibrils" in Fig. 17 and also visible in Figs. 1 and 2
a leaf?  I do not see any evidence of wing phalanges on either margin.  The
striations which are presumably interpreted as actinofibrils in Fig. 17 are
not arranged in the pattern seen in the Zittel wing and other undoubted
pterosaur wings, where they extend obliquely in a posterolateral direction
from the wing finger, but rather the striations seems to be the parallel
venation in a leaf.  If this is a leaf, then the details and interpretation
of the diamond pattern in Figs. 18 and 19 are suspect.


I hope my comments are of interest to some.

Chris


S. Christopher Bennett, Ph.D.
Assistant Professor of Basic Sciences
College of Chiropractic
University of Bridgeport
Bridgeport, CT 06601-2449