Search the Community

As I mentioned in a previous post, when I was at the Tucson Fossil Show I picked up some unprepared slabs of Green River Fish from the 18” layer. That prompted some of you to say you expected me to post photos as I did the prep work. I initially rejected that idea because I’m pretty bad at prepping and I didn’t want to post pictures showing how bad I am. But then I remembered some advice I once got from a manager I reported to early in my career. After I made an engineering decision that didn’t turn out so well, he told me, “It looks like your fate in life is to serve as the bad example everyone else learns from.” That cheery sentiment was underscored by this framed inspirational poster he had hanging on his office wall: So with that in mind, I decided to go ahead and post photos of my prep work, not to show you how to do it, but rather to give you the bad example everyone else can learn from. I picked up a total of four slabs, but the one I will show you in this and subsequent posts is one that was claimed to be a Priscacara species. Of course you don’t know for sure until you do the prep, but I wouldn’t be surprised if they had done some sort of X-ray before they put the slabs out for sale to make sure they weren’t selling a rare specimen for a dirt-cheap price. In any event I’ve been happy with the specimen, even if the quality of the prep could be better (this is my first time prepping a specimen from the 18" layer). I actually started the initial prep while still in my hotel room in Tucson, but I don't have a photo of this fish from there. Here's a photo of one of the other slabs to give you an idea of what they looked like. The seller drew a bunch of lines in pencil to show what he thought was the outline of the fish, so that's mostly what you are seeing here. It was a lot easier to prep once I got it home. I only have manual scribes so it is a very slow process. Here’s a photo of my setup. I’m convinced I would not be able to do this without the microscope, which I keep at the lowest setting, 6X. I have 3 probe tips, all purchased from Paleotools when I was at the show. I also bought two pin vises to go along with the one I already had. Of the probe tips, one is oval, one is flat like a flat-head screwdriver, and one is a sharp point. With my technique I have found the oval probe to be the most useful, followed by the flat tip. I only use the pointy one to do delicate cleanup in tight spots. To keep the dust from getting all over the place I mostly use the yellow brush to clean it off and save the blower for critical spots. Even then I don't use it at anywhere near full blast power. Even so, you can see it's already covered in dust. Here’s how it looks after about 5 hours of prep (I said it was a very slow process!). The tail looks like it has been blown up, probably due to decomposition before being covered with silt. The ribs are looking pretty good except for at least one that’s far out of position and pointing in a completely different direction than the rest. Looks like it has 9 dorsal spine rays, which is consistent with Priscacara serrata. The areas around the pelvic fin and where the caudal rays branch from the body were prepped by the seller, probably with air abrasion, I assume to help sell the specimen. Here it is after about another 3 hours, mostly to expose the anal rays and further clean up the dorsal spines. It has 3 anal spine rays, further confirming it identification. You can see my favorite probe tip on the left. Next up is to start working on the head, which will be more difficult because the matrix covering it is a lot thicker. This fish is definitely from the 18” layer, as the smell of petroleum is pretty strong. I’m finding I can only work for about half an hour at a time, two or three times a day. If I work longer, I get nauseous and get a headache that doesn’t go away for a day. So this is making the prep go even slower. I did a search on the TFF forum for other threads on prepping Priscacara from the 18” layer and found a good one from back in 2017, in which @Ptychodus04 recommended dampening the matrix to soften it. I have been doing this and it not only softens the matrix it also keeps down the dust and fumes. And it adds contrast when I take photos. Good idea! Here’s where I am at now, after about another 5 hours of work. The head is starting to emerge, but I have to say I can’t identify any of its features when I compare them to the photos from Lance Grande’s book, The Lost World of Fossil Lake. Not sure what is going on here, I’m open to suggestions. Meanwhile I will keep plugging away and post occasional updates as I have them. What are these bones?

I have seen the "18" inch layer" mentioned in many threads and posts. What is meant by the? Please explain.