[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index][Subject Index][Author Index]
re: Chris's anurognathid
Chris is correct. I have never seen his new anurognathid. Only a brief
glimpse during the slide show. And all my statements were merely
After working all spring and summer on the other four anurognathids,
(yes, working from photographs), I have gotten to know them better than
they were originally described, thus making snap judgements easier to
make (though still not free of faults).
As anyone who saw Chris's slide depicting the line drawings by the
original authors of Anurognathus, Dendrorhynchoides, Jeholopterus and
Batrachnognathus can attest, they are all pretty bad. Jeholopterus is
little more than an outline of a blob. In Batrachognathus many bone
impressions were ignored. In Dendrorhynchoides, a slightly better blob,
none of the skull bones were identified originally (Ji and Ji 1988,
1998), and all were misidentified subsequently (Unwin, Lu and Bakhurina
2000). In contrast to the literature, including Chris's abstract, all
are virtually complete (Batrachognathus is only missing some posterior
cervicals and anterior dorsals). True, they are not easy to understand
and perhaps this is why the original authors all "gave up" trying to
figure out the skull during description. One reason may be that none of
them had a useful guide as to how the crushed little skulls actually fit
together. Another reason is that much of the data is reduced to
impressions of bones, not the bones themselves. The wonderful thing is
that now we have four (or five) anurognathids and each one helps us
understand the other, especially with the aid of Photoshop.
The use of photographs to study flattened specimens, and impressions of
specimens, on the computer screen, is controversial at present. To
those of you who remember or have my drawings of anurognathids for the
Pterosaur Homepage ~ they're all badly flawed! They were based on the
literature and on blown-up tracings of photographs. I can tell you from
experience, that's where the errors come in. Oh, you'll make errors when
you trace your specimens in Photoshop, too, but the fact that the
tracing medium never leaves the specimen allows the errors to pop out
like crazy when you switch on and off the various drawing layers you
create. And because the medium is perfectly clear, the most subtle
impressions can be discerned, whether in the matrix or on a
black-on-black fossil, like Jeholopterus. That is so important. For
instance, I was delighted to find a finger on top of the skull of
Jeholopterus. That solved alot of problems.
Best of all one can share such files online.
That's why it is so imperative that when anyone begins to study
anurognathids, you study all of the "roadkills"as a group. Each one
presents a different aspect. I was disappointed when Chris showed the
original line drawings of the various sister taxa as his comparative
samples. I was hoping Chris had done the same work I had been doing,
discovering the flaws, rather than relying on them as his guides. I have
offered Chris all of my work on the anurognathids, but he has not
accepted the offer. It's only data, Chris. It would be better if you
rejected it _after_ seeing it. And it would be better if you saw the
data before you published.
A few quick points to air out in case the offer is still rejected:
The orbit enters the anterior half of the skull in Jeholopterus and
Batrachognathus and yet the antorbital fenestra is huge in both cases.
The little V-shaped splints with their apexes at the bases of the
ascending processes of the maxillae are, believe it or not, emanating
from the maxilla. Rather than, as others have described them "palatines"
and "pterygoids," they are homologs to the conjoined palate one finds in
Rhamphorhynchus and pterodactyloids. I don't know why they were reduced
or what they were used for in anurognathids, but they lie ventral to the
actual pterygoid and the ectopalatine (yes, a combination of the
palatine and ectopterygoid) all visible in all four taxa. I erred in my
2000 paper when I assumed the ectopterygoid had disappeared. As part of
the new ectopalatine the lateral process of the former ectopterygoid
retains a connection lingual to the maxilla/jugal suture, which is a
great guide. In anurognathids, especially Jeholopterus, the palate bones
are the most robust of all the skull bones. That's why I was able to
identify (IMHOpinion) the skinny long-stemmed bone on Chris's slide as a
lacrimal, not a pterygoid. They would run parallel to each other in a
crushed specimen. However, as in almost all pterosaurs, the lacrimal has
a head and a long skinny stem, often hidden alongside the jugal. In
anurognathids the lacrimal process of the jugal is reduced (or the orbit
is greatly expanded) exposing the stem almost completely.
I could not discern that pedal digit V was broken during the slide show.
All other anurognathids have four wing phalanges. The distal one is
small in all except Anurognathus, cladistically the primitive one of the
bunch. Therefore if Chris's anurognathid has only three wing phalanges,
I would expect it to arise from the more derived big-eyed forms already
Finally, I'm not the only one. Another professional who has seen the
specimen also thinks it is something new.