[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index][Subject Index][Author Index]

Seeing things in photographs

This just in:

After observing the holotype of Cycnorhamphus suevicus in France, and
taking pictures of it, and studying the photos for weeks, and doing my
little tracings, just last night I finally found the sclerotic ring.

Evidently it had softened up a bit during taphonomy and was just about
to completely merge into the parietal crest where it was emblazoned like
an RAF insignia.

It nearly completely fills the orbit, so there's another cladistic box
checked off.

Segue >>

Chris is right. You don't see everything the first time, or the second
or tenth time. Thanks for pointing out those two shards of bone inside
the skull of Anurognathus for me. Still not clear what they are or if
they are really as straight as you propose in your drawing. Would be
nice to see a photograph that brings them out as you say.  Just to
confirm the drawing.

Regarding the identity of the two shards, left unidentified on the web
site (unless I missed something), may I make the following guesses?

1. The left one and straighter of the two may be the ventral edge of the
jugal, which I drew and colored, but less straight (more decayed)
following my data, in green. It appears to be emerging from the matrix
like a cracker in a bowl of chili.

2. Alternatively, it could be one of the basipterygoids come to rest
along the margin of said jugal.

The right shard is more difficult because, although both you and
Wellnhofer drew it with minor undulations or zig-zags, it seems to be
(again from the photograph which can be viewed on your website) slightly
more ziggy and zaggy than either of you indicated previously. At first I
thought it could be the dorsal edge to the right maxilla I drew.
Although the right maxilla has been torn in half (the ascending process
is far away to the right) and teeth have been dislodged (witness the
crescentic saber-tooth, a first maxillary, near the ascending process),
it could be something else.

3. It could be the other basipterygoid, a little busted up.

4. It could be a splinter of bone off the wing phalanx just beneath it.
A fracture clearly shows across the phalanx right where the splinter
would have come off, but since the top is still cylindrical, the
splinter would have to have come from the underside of the phalanx.

5. Considering the zig-zaggy and, to my eye, layered-with-other-elements
look. It could be a short series of bones.

6. Finally, in non-dimorphodontids, the maxilla forms a shelf which
phylogenetically grows toward the midline to produce a solid palate in
higher pterosaurs. By contrast, in dimorphodontids the maxilla, starting
lingual to the ascending process or just posterior to it, sends out a
pair of wiry processes. We know those aren't palatal elements, as has
been suggested earlier, because the palatal elements are already
accounted for and present elsewhere on the slab. Previously I was not
able to find the maxillary processes in Anurognathus, so here's yet
another possibility.

Perhaps I didn't clearly mark the area because I didn't understand it.

As you can see, I still don't.

Anyway, that's the thinking process. Comments welcome.

Hey, guys?If you wish to dismiss the scanning/tracing technique as bogus
because of my inability to account for two bone shards on a slab, be my
guest. And while you're on Chris's website, see for yourself if there is
or isn't any new data worth collecting that was missed by the pencil and
the camera lucida.

I was aware of Wellnhofer's 1970 drawings which show almost to the T
exactly what Bennett's drawings do. I didn't see the bone shards as they
were presented but rather chose to present them as I saw them. One
camera angle, one lighting angle never shows everything possible in a
fossil. You, gentle reader, should decide for yourself through your own
experimentation whether the new technique brings _any_ new data to the
table. Or not.

And when someone says you missed something, guess what? You can fix it!

It's a new era folks. Lots of mysteries are going to get solved in the
next few years using computers and scanners. Lots already have.

David Peters
St. Louis