As I posted last time, I received a block containing the trilobite Asaphus lepidurus for me to prepare. Despite the three of this species I've prepared before, this one was by far the toughest due to the nature of the matrix being hard, sticky, and calcitic. It meant very slow scribing, micrometre by micrometre, under high magnification. Of course, I was having plenty of problems with my equipment that added to the aggravation.
This is the block when I got it, and then after an hour and a half of patient scribing with an ARO clone with the not so great factory tip. As thick as the block was (with trilobite at the bottom), I couldn't risk a chisel... So it was the long way down.
Several more hours as I also work the matrix down. The plan is to have the trilobite standing in this orientation, sitting in a depression. The matrix is starting to play tricks with my eyes. At this point, I'm slowly revealing the right pleurae, heading for the axis, and working around the cephalon.
This stuff is sticky, and largely impervious to abrasion even at higher pressures. It took several hours to find the other eye, negotiating very carefully so as not to accidentally scribe it off. Once the pleurae and axis were largely revealed, working that top of the cephalon took eight or so hours on account of extra stickiness. I also didn't want to knock off the diminutive tubercle by mistake.
After the left side pleurae are exposed at their tips, let the long abrasion session begin. I swapped between the Paasche with the 18 gauge dispensing needle (the disposable needles just arrived yesterday just in time) and the pin vise. There were several very stubborn, translucent bits of calcite to slow me down.
I finished it off with some matrix smoothing, and this is the end result. Measuring 80 mm. Despite the limits of my current equipment, and the unholy horror of this matrix, I managed to do some justice to this trilobite, exposed for the first time in 450 million years.
Been a while since I updated the blog, but winter is a slower time on the fossil front. Compared to last winter, even purchases are down as I either have most of the stuff on offer, it's too expensive, or it's not in pristine condition. But I do have a trilobite coming in a few weeks, and one other I received not long ago. This post will be a potpourri of odds and ends. Lots of stuff coming up...
Pictured here is a wee Acastoides sp. from Morocco. It was cheap and very nicely articulated, so I added it to the trilobite family. I've also had a bit more cash in the PayPal account due to selling some surplus trilobites.
I also managed to spend an afternoon adding to my trilobite sketchbook with these two Russian beauties.
It's a rock! No, not just a rock, but a Russian rock, and a Russian rock containing an asaphid I am currently preparing. Due to the nature of the matrix, and my current tools, this is a 100-200 hour job. I'll create a separate post when it's done.
Hobbling my preparation efforts has been a clogged air hose, likely in the built-in moisture trap for my Paasche AECR. One might think a basic air hose with a 1/4" - 1/16" would be a cinch to replace, but three hours of hardware store visits and plenty of time searching the web says otherwise. I finally got my part and am ready to get to the next critical phase in the prep, which involves swapping between scribing and abrading due to the stickiness of the matrix.
And that wasn't the whole of my prep equipment frustrations, either. I had just been talking with my friend Kevin, saying that I've gone over a year without needing a filter on my lines. Well, no sooner than I said that, the scribe starts acting more like a garden hose. So a trip to Princess Auto to fix that, and to locate a replacement hose (see above). I was also having serious air leak issues, and teflon tape for my big clumsy fingers usually results in my exhausting all the blue words I know, so I've gone for thread sealant instead. The filter/desiccant has already made for a much drier scribing experience. Nothing can be more frustrating than doing precision work under the scope while maintaining critical control of the tool than when it sprays water all over the fossil, turning scribing dust into cakey, opaque mud. And also pictured is a resupply of those handy nitrile gloves.
So when is the first dig of 2019? I'm hoping this weekend, weather and opportunity pending. I've got some other trips planned, too. It will be fantastic to get this season rolling and spend time with my favourite field comrades again as we swing hammers as spring clamours!
There are collecting locations that I'm not likely to get to in the near future, and as much as I'd love to fancy myself wealthy enough to just buy up every great Russian Ordovician bug, sometimes one has to settle for the discards.
Russian preparators who eke out a living collecting and preparing trilobites are not too different than the preparators who do the same thing here: there are those (far too many) finds that are simply not worth the time and effort for whatever reason. It could be a common bug that has too much compaction damage, bad mineralization stains, too many missing parts, or anything else that might result in producing a trilobite that is far less than A-grade for sale. Buyers generally expect perfection, after all, or something close to it. So into the chuck-it bucket it goes. I have my own "graveyard" of partials, botched prep attempts, and stuff far too common yet complicated to be worth preparing unless I had nothing else in the queue.
So this is the chuck-pile bug in question. Not quite complete junk, but pretty close. It was likely found busted and glued together in the field, which is a fairly common scenario when collecting from these layers. For every nice, full (sometimes floor polish enhanced) Asaphus sp. one sees for sale, there were likely hundreds of busted up partials (some of which get recycled as grafting material). This trilobite has a lot of problems beyond the fractures tentatively held together with glue: crush damage, missing shell bits, and serious mineralization discolouration that makes it appear mottled and less than pristine sale quality. But I need the practice!
I've never prepared an illaenid before, and there are always a few "firsts" I encounter while preparing given that I haven't been doing it for that long. Each prep is a learning experience, and making serious mistakes is part of it... But so is recognizing that each prep is different, even when dealing with the same species and matrix. You try different approaches and techniques, sometimes using a wide range of tools suited just for that particular job.
So, let's have at it.
The first step was to do the scribe work, but not before consulting numerous images of this species from different angles to give me a reasonable idea of what to expect while my scribe flies blind. My scribe sailed through this matrix! By contrast, the previous prep of an Asaphus lepidurus was a dismal failure as the matrix was a dense, calcitic mess that even 75 PSI dolomite wouldn't touch unless I wanted to eat through several canisters of the stuff.
The unique aspect about this genus is that the bulbous cephalon seems to go on forever. This was where I stopped the night before, and there was still a lot more matrix to remove. When they preserve in this kind of almost semi-prone state, it is customary to just blitz off the the anterior side of the matrix, which gives this burrowing bug the appearance of "hanging over" the side. This is all scribe work: I just needed to "kiss" it with the tip and the vibration would knock off the matrix without me risking hitting the shell with the scribe tip.
And this was where I had to call it a night... Not just because I didn't want to run the air compressor beyond 10 pm and be a loud nuisance, but on account of the other result of such a soft and yielding matrix is that fractures emerge that run deep and threaten to wreck the trilobite. Pictured here is my stabilizing some vibration-made cracks by wicking some cyanoacrylate. A good ending point for the day to let it cure and get back at it in the morning.
As soon as my missus went to work, I was firing up the compressor for round two. At this point, the scribing work is pretty much done as far as I'm willing to risk it; what remains are some delicate areas that need to be air abraded. I do alternate between scribing and some air dent to test certain spots, but I'm a task-switcher by nature. The tricky spots are going to be the eyes and the genal spines.
It isn't a true prep session unless you experience a minor catastrophe (at least that is the norm for my inexperienced self!). The very thin-shelled underside of the cephalon didn't quite dig my air abrasion action, and so some shell bits went flying. I retrieved a few pieces, which is not easy to do in a dust layer in the blast chamber (or in the shop vac bag). And I don't exactly have those tiny fingers adept at threading needles. I reattached a few of the pieces I found, but some of them were lost forever. It could have been much worse, and I managed to fill in the much bigger "bald spot" with the pieces I could glue back on. This is a discarded bug anyway, and not a presentation to the Queen.
Air abrasion work reveals the eyes and frees out the gunk between the pleurae and the genals. I've moistened it with some oil to better detect other areas I might have missed.
Yes, I am such a prep noob. I will, however, take immense pride in how I managed to free up that genal spine (which had a crack in it, no less) to be my first "flying genal spine." For those who do not prep, this may seem very easy, but it is fraught with a lot of nervousness and care to ensure not blasting the spine off as a sacrifice to the hungry shop vac!
And this is where we are. I also sanded down the matrix (decided to leave a bit for aesthetic reasons). There is some cruddy glue stuff on the left pygidium that needs an acetone bath (abrasion is too risky at that section), but otherwise not bad at all for preparing what had been consigned to being a junk bug. I learned a lot, and ended up cussing a lot less while doing this one. To me this is a prep triumph.
Made a trip to the post office to pick up a backlog of packages that couldn't be delivered at the door, and it was a lovely little bonanza of bugs.
Although a bit beat-up and sticky, this will be added to my winter preparation queue. This Ordovician corynexochid is Illaenus sinuatus, a new species for the collection. The cephalons on these kinds of burrowing bugs tend to be fairly robust, so there is considerable matrix to be removed. I'll post the complete results once I get this in the lab.
Another Ordovician trilobite, the phacopid Pliomera fischeri, from Kinnekulle, Sweden. Trilobites from the Swedish part of Baltoscandia do not tend to preserve as well, and can come out fairly weathered.
From Haellekis, Sweden, an enrolled Ordovician phacopid, Nileus armadillo.
Although I already have two other examples of this species, a small and enrolled Asaphus kowalewskii will nicely complement the Russian asaphid display.
Top prize for this bug bonanza would go to this lower Devonian Moroccan phacopid, Wenndorfia planus. Nicely enrolled, and uniquely prepared in a tilted pedestaled fashion to show off its "assets," this trilobite was reassigned by Sandford (2005) to Wenndorfia from the species Parahomalanotus... which in itself was possibly mistakenly elevated to genus status. For those interested in some of the twitchy taxonomic tango see:
Sandford, A.C. (2005)
Homalonotid trilobites from the Silurian and Lower Devonian of south-eastern Australia and New Zealand (Arthropoda: Trilobita: Homalonotidae).
Memoirs of the National Museum Victoria, 62(1):1-66
Basse, M., & Franke, C. (2006)
Marine Faunen aus dem frühen Unteremsium (Unterdevon) des Givonne-Oesling-Antiklinoriums (Luxemburg).
Chatterton, B.D.E., Fortey, R.A., Brett, K.D., Gibb, S.L, & McKellar, R.C. (2006)
Trilobites from the upper Lower to Middle Devonian Timrhanrhart Formation, Jbel Gara et Zguilma, southern Morocco.
Palaeontographica Canadiana, 25:1-177
A number of trilobites came in the mail, with several more waiting at the post office and some in transit. First up is a Paralejurus dormitzeri
This fairly common Devonian corynexochid from Morocco does appear fairly often for sale, but a lot of them are the victims of quick and brutal preparation. This one has very good quality preparation, with some minor restoration on the lower right pygidium. Finely detailed with the eye lenses, terraced growth lines, and pedestaled to show the cephalic doublure. Only a few scribe dings, and measures close to 80 mm.
A cute and small Asaphus kowalewskii. Although I already have an example of one (semi-prone), this young holaspid stage specimen was too adorable to pass up. Some slight compaction between the third and fourth axial ring, but virtually no restoration of this stubby-eyed example of the species.
Hooray! Another winter prep project to keep from going bonkers from fossil hunting withdrawal. This is a relatively small semi-prone Asaphus lepidurus.
Until tomorrow when a few more trilobites join the collection...
This may bring my winter asaphid purchases to their conclusion for the season as it is time to collect from more than just the postal formation! And I may as well end it with a proverbial bang.
This whopper of a bug is Asaphus raniceps, clocking in at about 100mm. You can make out some minor restoration, which is fairly standard.
This googly-eyed monster is the intermediate species between Asaphus punctatus and A. kowalewskii: Asaphus intermedius. Okay, not the most creative and inspired example of binomial nomenclature, but it underlines the point that this is indeed an intermediate species. These sky-high peduncles were a response to increasing turbidity in the Iapetus Ocean. Their entire bodies would be buried in the sediment with only the eyes showing - ideal for hiding and predation.
This is a rubbish shot and arrangement, but I'll be organizing this properly later. I just wanted to show off the collection of these Russian googly-eyed asaphids. Absolutely beautiful, and I am quite proud of how I managed to collect so many... Although they were not cheap!
Today I received a few packages in the mail, including one Czech trilobite and five Russian ones.
Here, four asaphids and a corynexochid are gathered around a trio of ptychoparids. A reflective moment for these Ordovician trilobites with the much older Cambrian trio in the centre.
This is Ellipsocephalus hoffi from Jince in the Czech Republic, Cambrian in age. This is a nice assemblage. These are what are known as blind trilobites as, well, they have no eyes!
Illaenus sp. (?oblongata), a Russian corynexochid from the Ordovician.
Readers of this blog might recall when I was preparing an Asaphus lepidurus not long ago. This is what a full, professionally prepped one looks like.
Here is the same specimen on its ventral side, showing off a very nice hypostome!
This is definitely "wide-load" - Asaphus latus. Almost as wide as it is long.
The aptly named Delphasaphus delphinus fully prone and looking a bit like a dolphin... if a dolphin were a segmented arthropod from over 400 million years ago.
This is the biggest of today's acquisitions at over 76 mm: Asaphus holmi. Below is the ventral side showing its hypostome:
A four hour preparation session reveals a full Asaphus lepidurus.
I knew this one had problems going into it, such as discolouration of the shell, some very sticky calcitic film, and possibly some damage. However, it turned out much better than I anticipated.
I had thought it was likely missing a good chunk of the left side, but I was delightfully incorrect. It is a bit crushed/flattened out on that side, though, but worthy of being put in the display cabinet.
Time lapse GIF above, and a "before and after" picture side by side:
And finally just two pictures detailing how I got into the nooks and crannies. The entire prep involved a range of tools (air scribe, two Dremels, a lot of pin vise work, and Paasche AECR air eraser using dolomite at pressures 20-40 PSI). Believe it not, most of the work was painstakingly done by hand with the pin vise. As the matrix is far too thin on the left side, and the pleural segements stretched out / flattened which makes them a bit more fragile, I'm leaving that side alone.
I received my newest batch of Russian asaphids today, and all credit due to Mikhail for his preparation skills. These are large and perfectly prepared trilobites, a welcome addition to my growing collection.
So the trio I got today. On the top is an Asaphus lepidurus for me to prep. On the left is an Asaphus expansus gracilis. On the right is the aptly named robust Asaphus robustus. Wow. The pictures hardly do these justice, but I will be re-shooting images for the trilobite gallery soon.
A. expansus gracilis.
I traded some material with a friend on the Fossil Forum and just received an immensely generous package filled with new trilobites that will be added to the gallery.
Pseudoasaphinus gosilicyensis - sitting atop a Proterocameroceras mishinagorense. From the Gosilitsy Quarry in Russia.
Modocia brevispina - Middle Cambrian, Wheeler shale, Utah
An Asaphus latus for me to prep! From Russia.
An Olenellus gilberti from the Cambrian. Pioche, Nevada.
Assemblage of Ptychagnostus richmondensis from the Wheeler shale in Utah. Mid Cambrian.
A Piochaspis sellata from the Chisholm shale of Pioche, Nevada (Cambrian).
The tiny Bolaspidella housensis from the Wheeler shale of Utah (Cambrian)
A fabulous pair of Itagnostus interstrictus from Utah's Wheeler shale (Cambrian)
The very last on my list, alphabetically, Zacanthoides sp. (?typicalis). Cambrian, Pioche, Nevada.
A complete surprise (apart from all the surprise new specimens above!), a genuine Spinosaurus tooth!
I ordered these cool membrane frames for cheap online, and that will help fill this:
Deb's birthday present to me, a lovely glass display cabinet to host all my lovely trilobites!
So, wow, what a great haul today!