Defending Photoshop

[david peters <davidrpeters@earthlink.net>]

Thanks to Paul Sparks and others for bringing this bad penny back.

All I can say is the following:

With Longisquama you're dealing with a specimen that is covered in _a lot_ of 
skin. More skin than most tetrapods because this lizard (and it is a type of 
lizard) had more extradermal membranes and plumes than a Brazilian drag queen 
on Mardi Gras. Much of the skin overlaps bones which makes them hard to see. 
I've mapped out all the bones and skin boundaries and embryos I could discern 
(and that means I had such a very hard time seeing some of them that they only 
became recognizable _after_ the tracing was done). The toes were seen before, 
but interpreted as subdivided plume shafts. The femur was seen before but 
interpreted as plume going off in a different direction than the rest of the 
plumes. So I was not the first to see these structures. I only did the tight 
tracing that revealed how they were all connected together. 

To Jaime who put his eye close to the fossil cast looking for clues: I don't 
think the human brain can disentangle the chaos enough to discern what you 
think you should see. Much like, no human can create a cladogram in his/her 
mind. You simply have to do the tracing and _then_ see what you get. It is 
non-traditional. And it will be frustrating to those who think they should just 
'see' something.

It won't happen. I can tell you it doesn't happen with me.

It would be nice if someone could duplicate the method (so far no one has sent 
me tracings for approval/verification/condemnation/whatever). Even so, vanity, 
arrogance, stubborness (I suffer from all of these just as we all do) will rear 
it's ugly head. No one likes to back pedal or recant. It's horrible. I've 
choked on it and survived. 

Some of those little soft bone pterosaurs I was seeing turned out to be 
[possibly] pre-shell embryos, now possible in the pterosaurs as lizards 
scenario. It could be that they only wore the shell for hours or days. Others, 
as Chris Bennett pointed out, were merely hopeful pin scratches. Easy to 
mistake in pterosaurs because all folded up they do look like a jumble of 
PickupSticks.

But in the meantime, isn't it nice to know that what starts off as jumbled 
tracings of ephemera pull together to create a series of morphologies that make 
sense? That resemble one another? That provide antecedence and reason for 
various bizarre structures that come later? I was surprised as anyone when the 
length of the Longisquama legs and torso came to light. But then, after all, it 
is a sister to Sharovipteryx. And it was built like a lemur, as Chris Bennett 
echoing van Huene hypothesized in his prescient 'pterosaur ancestors were 
leapers' paper. I was also surprised to see the juvenile had short legs, huge 
feet and a short torso, more like a pterosaur. But then, you think about it, 
and it makes sense! Paedomorphosis.

I also want to tip my hat to those who interpret the same fossil differently 
after seeing the same structure/fold/line/doodad. 

Don't knock the technique or the interpreter. Knock the interpretation. And 
knock it's head off if it's bad.

Or better yet, come up with better tighter observations that put a new spin on 
things. 

David Peters
St. Louis

PS More dust will be raised with my interpretation of the skull  of 
Sharovipteryx. Just remember that every other bone in this specimen was 
preserved in place and undisturbed. And no one else has even attempted to 
update Sharov 1971. That makes nearly 35 years that this treasure has lain 
dormant. Did I mention there are two ant/wasp-like insects preserved in the 
skull? That's how good preservation is.