While I had the compressor running, I figured I'd do a quick blast on what will probably be a very challenging prep this winter, as well as preparing some "low-hanging fruit" in the form of a prone. First, the investigative quick air abrasion blast on this Greenops widderensis roller with flying genal spines. This one will certainly be a major challenge to do without screwing up. I'll probably end up cutting the rock a bit above the spines and delicately work my way down to reveal the other side. This was the low-hanging fruit: a small Eldredgeops rana prone from my Penn Dixie weekend. The matrix is very thin on one side, so there was the risk of the trilobite flaking.
For this post, I will be showing the progress on preparing the largest Eldredgeops rana that I have ever found at Penn Dixie. This post will be updated once the preparation process is complete. DETAILS:Taxonomy: Eldredgeops rana (Green 1832) Geology: Mid-Devonian (Givetian). Hamilton Gp., Moscow Fm., Windom Mbr. Provenance: Field collection (K. Faucher), October 13, 2018. Hamburg, NY, USA DESCRIPTION:Specimen is a large individual for the species and location, likely latter holaspid stage as opposed to simply being of an anomalous size at an earlier phase of development. Evidence of pronounced and widespread pustular sculpture may attest to this. Specimen is oriented in a semi-prone attitude with high convexity to mid-posterior thorax, with posterior thoracic area pointing downward. Specimen is also oriented transversely with a shift or dip leftward into the matrix. Compaction damage to the glabella evident, in addition to apparent crack in palpebral lobe (left side). Specimen measures (from anterior tip of glabella to final posterior thoracic segment) 60 mm along the dorso-saggital axis, and 42 mm on the transverse axis. TAPHONOMYWindom Member shales present the conditions of rapid mud burial. Such catastrophic events result in more ideal conditions for preservation of well-articulated specimens, both body and moult fragments. Enrolment is a common feature as a defensive behavioural response to the sudden stimuli of these mudslides. Field observations (anecdotal) put the ratio of full prone, semi-prone, and enrolled specimens of E. rana in these layers as roughly 1::5::10. Frequent ecdysis of the species furnishes several moults of isolated cephala, pygidia, and intact thoracic exuviae. These are commonly aggregated due to currents, or moulting grounds in gregarious groupings. Fused cephala (no cephalic sutures) meant that this species would commonly exuviate at the weakest point in the exoskeleton, between the cephalon and the thorax. Taphofacies of this section of the Windom Member ("Smoke's Creek Layer") indicate a relative degree of bioturbation of muddy sediments, the presence of worms, and significant pyritization. Groupings of trilobite remains are generally sorted according to similar size, but this is not always the case. REMARKSIt is so far assumed that the specimen appears as it did in its life position. No presence of predation marks, parasitism, or disarticulation due to hydrodynamics or decay. Being of a significant size, it also presents some distortion on its left side likely due to compaction. PreparationPreparation of the specimen was undertaken using an ARO-based air scribe to remove bulk matrix, while a Paasche air abrader set at various pressures and using dolomite as the blast medium was used for detail work. Specimen as found in the field. After 1.5 hours After 2.5 hours After 4 hours. Another few hours will be required to complete the preparation, including matrix sculpting and scribe mark removal. A smaller enrolled specimen was discovered during the preparation process, which will also require preparation. 2.5 hours later. And pretty much as far as I want to take this one. Not perfect, but pretty close as I continue learning the art of preparation.
posting this on the final day of a three day dig at Penn Dixie in Hamburg, NY. Earlier in the week I dug with Fossil Forum friends in the Thedford area, and have been amassing finds over several trips. No pics of those hunts yet, but that will happen once the season is over. We moved a lot of rock this weekend, and found a lot of trilobites. Pics of those when I get the chance. For now, site pics to show our work. This shows the state of the dig area cleared out after Friday when I joined the other crazy Canadians. As soon as I got there, the human backhoe that I am went right into ripping out large slabs. The fresh stuff is where the best preserved fossils can be found, as opposed to the stuff that has been left to weather out. We do serious earth moving! The trilobites appear mostly at the Smoke’s Creek layer of the Windom Member, or the bottom 15 cm from the contact with the Bayview, just below the water table. By the end of Saturday, it was mostly just me and Deb, with Jay popping by. Thanks to him for supplying me with wedges. I carved out the slabs while Deb broke them down. Pictured above is the view from one end of the excavation. I managed to double the area (to the shovel handle in the background). The photo hardly does the size of this much justice. There are a lot of fossils to photograph (about two 5 gallon buckets so far), giving me a lot of winter prep material. This one above is among the largest Eldredgeops rana trilobites that can be found here. This is going to prep out beautifully. A semi-prone position with pygidium tucked underneath. Rollers are common, but prones are not as frequent. I also found a Bellacartwrightia (looks like a Greenops on steroids) in ventral position. Lots of rollers and prones were found. Some snaps of me caught by our shutterbugs on the Friday. Top two photos by Monica P., and bottom two by Ken M. And this is how we left the place on the Sunday. Some serious excavation as about 250 cubic metres of rock were extracted and split. The FindsSeveral buckets of goodies were collected, and these are a few of the better pieces. These are being kept as-is until winter prep time. Full prone Eldredgeops rana in an assemblage with partials/moults of similar sized specimens. - Ventral side Bellacartwrightia sp. with doublure and intact left genal spine in evidence. Although a ventral prep is possible, I may stabilize this and prep it dorsally. It is uncertain if this is complete beneath the matrix, or just the cephalon. Pygidium showing of a Greenops sp. Unclear yet if it continues into the rock, but the presence of thoracic pleurae is a positive sign. Sadly, some of the lappets are missing. These asteropyginae trilobites are far more delicate with thinner cuticle than the Eldredgeops rana, and so are more prone to disarticulation due to hydrodynamic forces Two prones. The one one the left will be an easy prep. The one on the right was Deb's first in the field repair. She had accidentally flicked off the piece (shown with the whitish residue of cyanoacrylate) and I miraculously pulled it out as the first shard from the muddy, opaque water where it fell! It has not been reattached incorrectly; it has become disarticulated at the fourth pleural segment, possibly on account of compaction (which has also flattened it). Two semi-prones. The one on the left is missing a bit of the glabella. Assortment of rollers and semi-prones. Unless the rollers appear as more than one in the matrix, I tend to free them from their shale confines. Although the split sheared the cuticle, I kept this complete roller on account of the large calcite grains in evidence. Another full, albeit small, prone to prep. On the right is what remains of the throrax of the rare Bellacartwrightia sp.
In all, not a bad few days, but far from my best haul from this location. Gregarious trilobite assemblages were not much in the offing as we chased through the slabs for pulses in the Smoke's Creek layer of the Windom, coming up with a lot of very dense, blank or mostly coral-littered shale with no apparent bedding planes. Without the latter, it becomes mostly guess-work and luck with the hammer to bash the slabs open at the right spot. My next post will follow the process of preparing my largest bug from this dig, and then it's off to Bowmanville for the biannual Ordovician quarry visit in search of Isotelus and Ceraurus. No rest for the weary! After the big multi-day dig, I was up in Barrie helping to downsize a house and got to keep some supplementary tools that will help at the prep bench and in the field. A selection of awls, sandpaper, tiny screwdrivers, and even a fish knife all come in handy when paired with the precision tools I use. So began a bit of prep. This is the placoderm plate that I chased to its end. I'm thinking it is a plate from Protitanichthys rockportensis. I'm always looking to hone my preparation skills, so practicing on less than perfect trilobites is ideal. The one on the left is by far the best of the two, but could still use some restoration on the right side by grafting a bit of cephalon and the right genal spine. Small and battered, this goniatite is now clean. Although incomplete, this Tornoceras unioangulare has some stunning detail after I put it under heavy abrasion. A pity this one is missing a few pieces, but not a bad preliminary prep if I do say so myself! Some of the other trilobites are going to be much tougher work, and they are also missing pieces. The main thing is that my prep skills are improving with practice. Beyond that, someone from the University of Calgary has shown some interest in the placoderm pieces I pull from the Widder Formation. There is a remote possibility that I might have something new to science, but who knows? Just as a refresher, two previous placo pieces that might be worth studying: It's just too darn hot to go out collecting these days, but I'm really hoping to get out there relatively soon, if not also a possible trip to Western NY pending Deb's work schedule.
With the long weekend in full swing, I decided to get up early and have a look at the pit/pond just beyond my backyard. Much of it is Bois Blanc and Dundee Fm fill. I've made a lot of posts about the area in the last five years. This time around, I found something new. I spent some time in a 10 m x 10 m area by the pond, breaking whatever looked promising. I've found some interesting gastropod steinkerns in the past, and this one was no exception. Trilobite partials to the left, a brachiopod on the right. Typical fare for these lower to mid Devonian rocks. A nice split with a little bit of everything - mostly brachiopods and one horn coral calyx (the round item). A high-spired gastropod steinkern (partially buried in matrix) with its impression. Closeup of a bryozoan. More trilobite partials (two pygidia impressions and one cephalon impression fragment) Eldredgeops sp. cephalon fragment. Believe it or not, this was the major find of the trip. Although it is only about 2.5 cm wide and kind of looks like it could be a fragment of coral, it is indeed a trilobite fragment... but which one? I also ensured to collect the negative as well. It is a good idea, when in doubt about a specimen, to collect it - and all the other pieces it is associated with! So to which trilobite does this "toothy" fragment belong? Courtesy of our resident trilobite expert Scott, on The Fossil Forum, the answer can be found here: Stauffer, C.R. 1915 The Devonian of Southwestern Ontario. Geological Survey of Canada Memoir, 34:1-341 It is Odontocephalus sp. and as Scott tells me, in the last century or more, this trilobite has only been reported in a few papers from Ontario, thus making this a far from common find! Pictured below is a simplified line illustration of what it looks like complete. So... that's quite exciting! This site has now yielded up the following trilobites in the last few years: Eldredgeops rana Proetus sp. Anchiopsis anchiops Trypaulites erinus Mannopyge halli Odontocephalus sp. (?selenurus) This figure from Lesperance and Bourque (1971) shows the evolutionary branching from the genus Roncellia. My recent find means that I have representatives of each of the three major synphoriinae branches (Odontocephalus branch, Anchiopsis branch, and Trypaulites branch). What distinguishes them significantly is both the anterior glabellar process/border, but also the pygidial "spike" (or lack thereof). Note here the bifid spine that appears in both Odontocephalus and Coronura.
At this point, I am a bit more confident in assigning this one to the species of O. selenurus given the presence of 9 rather than 11 glabellar denticles as would be found on O. aegeria (which is also not reported to be found outside New York). According to Stumm (1954), only three fragments of O. selenurus have ever been found in Ontario; the first, by Carl Rominger in 1888, and two by Stauffer in 1915. Assuming no further fragments have since been found, my find would be the first in 103 years, and the fourth in Ontario's paleontological history. This makes this find quite exceptional and rare! This particular species is cited only a few times, including in Stauffer (1915), Stumm (1954), Lesperance and Bourque (1971), Lesperance (1975), Sanford and Norris (1975), and Ludvigsen (1979). Sources: ______ 1. Lesperance, P. (1975) Stratigraphy and Paleopntology of the Syphoriidae (Lower and Middle Devonian Dalmanitacean Trilobites). Journal of Paleontology 49.1: 91-137 2. Lesperance, P. and P.A. Bourque (1971). The Syphoriinae: An Evolutionary Pattern of Lower and Middle Devonian Trilobites. Journal of Paleontology 45.2: 182-208. 3. Ludvigsen, R. Fossils of Ontario: The Trilobites. ROM. 4. Sanford, R.V. and A.W. Norris. (1975). Devonian stratigraphy of the Hudson Platform. Geological Survey of Canada, Memoir 379 I. 1-124; II. 1-248 5. Stumm, E.C. (1954). Lower Middle Devonian Phacopid Trilobites from Michigan, Southwestern Ontario, and the Ohio Valley. Contributions from the Museum of Paleontology, University of Michigan XI.11: 201-21. 6. Stauffer, C.R. (1915). The Devonian of Southwestern Ontario. Geological Survey of Canada Memoir, 34:1-341 I managed to spend some time this week preparing a few of the finds from Penn Dixie. It looks like I had a few more full trilobites than I had thought, so there was a good deal of material to practice on. Preparing these Eldredgeops rana is a fairly straightforward job. The shell is thick and forgiving, and there are no big spines, flaky lappets, complicated horns, and the like to present much difficulty. I managed to prepare three, which I'll show in ascending order by size. Bug #1 - 1.7 cmThis one was fairly small, but I had recognized it as being complete in the field, and my friend Malcolm was able to chop it out of the block with his saw. There are areas on this where I could have bit in a bit deeper around the sides and the anterior of the glabella, but these smaller ones can be a bit tricky. I may take this one back to the bench for some detail work. Process: a quick trenching with the ARO clone air scribe, some spot work with the pin vise, and three rounds of blasting at 55 PSI using dolomite and the Paasche AECR. No finishing oil applied. Time: 25 minutes Bug #2 - 3.8 cmThis shows a before and after picture (in the field, and after prep). This was one of Deb's finds, so I took care not to screw this one up! There is some slight damage to the left side pleura near the ridge of the cephalon, and some damage to the right side pleura as well, but in all not a bad prep. Process: Alternating between ARO clone scribe and Dremel, pin vise work, multiple rounds of dolomite blasting (20-60 PSI) using Paasche AECR. Finishing is just a light oil to bring out the detail, but it fades back to matte. Time: 90 minutes Bug #3 - 4.6 cmBefore and after This big bug had some issues. When I found it in the field, it had been cleaved diagonally, so there is some missing pleurae bits on the upper left and lower right where the rock had split. I wrapped it up in a secure container, and when I got home I used cyanoacrylate to stick the pieces together with some clamps, and suitable time for curing. Despite the ugly fracture mark with some stubborn glue, it looks okay. I may take to trimming the excess matrix on either side to better centre this bug.
Process: The right side had a lot of bulk matrix which took some time to scribe off. I trenched around to reveal the tips of the pleural segments and cephalon features, sculpted the surrounding matrix a bit to even out the jagged parts, sanded off the scribe marks, and blasted it with dolomite (25-55 PSI) with the Paasche AECR. Time: 75-90 minutes There are a handful of others that will need prep, including both prones and rollers. With time and practice, I am doing much better in terms of technique - but there is still a lot to learn. Fortunately, I'm in no hurry and will hopefully have decades to fine tune my preparation skills. Here are the others in the prep queue: four rollers and two prones: DAY 1: Penn DixieReturned Monday evening from four fabulous days swinging hammers, slabbing and splitting in the field. We managed to hit two sites, with plans for a third site falling through due to weather and site conditions. We left home on the Friday morning to arrive at Penn Dixie, in Hamburg/Blasdell NY (south of Buffalo) by noon time. It was not a public collecting day at the site, but members of the Hamburg Natural History Society are permitted to enter the site. A group of us digging through some fresh material Of particular note was just how much PD had changed since last season, and that is due almost entirely to some well-directed excavations at some key spots to reveal more of the Smokes Creek trilobite layer, but also opening up other on-site locations such as the Bayview brach layer and the North Evans limestone. We had the excavator on site for the second day, with the previous day ripping up a new spot in preparation for the annual Dig with the Experts event. We did not touch those piles, and focused on other spots. I found this piece of Devonian wood, and it is a fairly healthy size for this location. One of the excavated spots we spent the most time working on was fairly thin on trilobites, which suggests that they appear in deposition pulses on the seabed. There's no way knowing in advance if there will be a lot of trilobites, and so you hope to hit paydirt by attacking the Smokes Creek layer. A fairly large Goniatite, sadly all busted up. Later in the day, we migrated to a new gully area where some of our other collectors on the Sunday previous had found a few examples of the rare Bellacartwrightia whiteleyi trilobite. Sadly, that lead dried up and no Bellas were found. For the most part, trilobites were mostly appearing as disarticulated bits and moults, with not much in the way of assemblages or complete prones and rollers. Full prone, but containing shell on both sides of the rock. This will need to be glued together and prepared. I did have some luck despite the parsimonious nature of the slabs we were splitting. However, the "trilo-bonanza" was still eluding us all. A little before sunset we decided to leave and check in to our motel, grab some pub food, and rest up for day 2 of our trip. DAY 2: Deep Springs RoadAt around 6 am the next morning, our friend Jay picked us up at the motel to begin our first ever trip to Deep Springs Road in Central NY (Madison Cty). DSR, as it is known, has a shale outcrop that rests at the farthest edge of the Windom Formation, but the fauna is quite different than what is found at Penn Dixie. For example, instead of bountiful Eldredgeops rana, they are much rarer here, and in their place are more Greenops sp. and Dipleura dekayi. Also, the real stunner is the enormous diversity of bivalves and brachiopods. It is also quite abundant in Devonian plant pieces, larger cephalopods, phyllocarids, and other goodies. Our crew gearing up to work. We arrived just after 10 am, having gone through the scenic rolling hills and farmlands of Central NY. We were greeted at the site by so many of our Fossil Forum friends, some of whom I got to meet in person for the first time. There was no shortage of fun-loving personalities here, and the amount of camaraderie, sharing, and helpfulness was exceptional. Jay and me ready to start wrecking it all up to do some serious landscaping. Within five minutes, I was ready to get to it. In the picture above, that wall behind me would be the first to be ripped out to generate a lot of slabs for splitting. By the end of the day, I would have cleared an area 2 m x 2m x 1.25 m. This slab simply has to go, 150-200kg or not. Unlocking fresh stuff requires some slabbing, something I tend to enjoy doing. After some overburden was cleared, it was time to maneuver this one off the ledge. As can be seen above,. the rock is heavier than me as I sit on the pinch-point bar which was bending. Eventually, I was able to work from the left wall, wrestling it out, and driving it with my boots down the hill for others to split. Group shot. From left to right: Dave, Jay, me, Mike, Tim, Dave 2, Jeffrey, and Leila (who fed us scrumptious homemade cookies). The weather had been promising to make this trip a real bust, but fortunately we only had some intermittent drizzle, with the rest of the time being clear and not too hot. Everyone came away with lots of interesting finds, and friendships were formed or strengthened in breaking rock together. Bivalves and gastropods. I'm not really up on the taxa, but these are fairly typical finds for this site. More neatly ridged bivalves. Large spiriferid brachiopods are fairly abundant at DSR. On the left is a nice association piece: a spirifer, a Greenops pygidium, and a Devonochonetes sp. . On the right is a high-spired Glyptotomaria. A well-preserved Cimitaria recurva. Deb found this wee Greenops that might be complete once I can remove some matrix. This one is barely a few millimetres long. As Eldredgeops rana are not common here, I bucketed this roller. Large cephalons from Dipleura dekayi. Finding them full as opposed to moults and disarticulated bits is an event. I think only one of us found a complete prone that day, while someone else found a complete one with the head disarticulated. More Dipleura dekayi. I'll need to probe this piece a bit more to see if they might be complete (but I somehow doubt it). A nautiloid and an ammonoid fragment. With the collecting day over, it was time for us to get back to the Buffalo area. As is natural for us fossil collectors, we never miss an opportunity if we're collecting together to share some gifts. A massive amount of gift exchanges ensued! I was sure to hand out plenty of goodies from Arkona, as well as whatever Ordovician extras I had lying around. Pictured up here is a lovely Herkimer diamond from Dave. These quartz crystals are quite spectacular, and regularly have inclusions of anthraconite. Another of Dave's wonderful gifts: an assortment of mostly brachs, bivalves, and gastropods from Cole Hill Road. The other Dave put out a box for all of us to take whatever we fancied. This is a fern from the St Clair site, a site that is no longer open to public collecting. Of course, little did I know that Tim remembered that Deb really liked those St Clair ferns, and so she received some pieces as well! Tim gifted me a plethora of trilobites. Two new species on my list: Crotalochephalina gibbus (the Devonian phacopid from Morocco at the very top), Changaspis elongata (a wee corynexochid from the Cambrian, China), a full Greenops sp. from DSR in case I had no luck, and three nodular Eldredgeia venustus from Bolivia. And the second bunch from Tim. A large Elrathia kingii with cheeks intact + impression, and the rest are Eldredgeops rana. And Jay gave me a copy of the reprinted classic, Geology and Palaeontology of Eighteen Mile Creek by Grabau. The taxa listed in this one is pretty much the same as what is found at Penn Dixie, and some of those taxa are now outdated or reassigned. But it is indeed a classic from a real pioneer and giant of palaeontology. DAY 3 - Penn DixieAfter two days collecting with Fossil Forum friends, it was now time for Deb and me to hit out on our own. Plans to visit another site on Sunday were nixed on account of weather... Yes, it was snowing in the Buffalo area! Deb went shopping in the morning, but by the afternoon the sun was out, so we figured we may as well play at Penn Dixie again. Although it was 10 C, the winds were bitterly cold. Deb standing in the newly excavated zone we were all working on the Friday. We decided to make a go of trying to find the elusive trilobite layer. This involved a great deal of hauling out slabs. Again, we treated the piles for the Experts event as off-limits. The Smokes Creek layer is usually at or below the water table. This is what one of the gully areas looked like before I came in to rip out about 2 m wide of slabs. Sadly, the rock was far too dense, and shattered rather than split. Much of what was coming out was just bits and pieces anyway. This trio of images shows the process required to access fresh material. As these slabs at the contact layer tend to interlock, it is important to kind the keystone slab to unlock them. In this instance, I've used the chisel to exploit and widen a crack running vertically. This one is tucked under another rock, so I had to use the pry bar to wiggle and jiggle it out. After that, I flip the rock over and scrutinize the underside; if there are trilobites or impressions thereof, I then carefully inspect the mini-domes at the site of extraction. As the water is muddy, this is largely done by touch. After that, it is time to remove another slab or split the ones I have. Probably my best find of the day. The split runs right through the trilobite, but some crazy glue and prep will make this fairly large one turn out just fine. This one came with a small price to pay. As I was tossing down a slab, it hit the pick end of my rock hammer, which then came at my face like a bullet. It struck and split my cheek, not far from my eye! It could have used a stitch or two, but I simply clamped it together with a bandaid. Day 4 - Penn Dixie (Again)After three days of slabbing, splitting, pounding with sledges, wrestling with pry bars, shovelling tons of overburden, my body just about had it! It was also our departure day, which meant we needed to get back on the road by 2 pm at the latest. So we agreed to inspect the newly excavated Bayview brachiopod area where, last October, we were pulling out buckets of brachs. This stuff splits fairly easily - sometimes just with your hands. Trilobites like Greenops are much more common here, but the shale is so thin and fragile, and the trilobites usually only come out as disarticulated bits. Brachiopods come out easily from the shale, if they haven't already weathered out and make for some easy picking. These are from about a minute of searching. Inasmuch as we agreed that we'd just do some light surface collecting, after 20 minutes we were getting bored with the brachs (we still have several hundred of them from October's visit),.so we went exploring back to the trilobite beds in search of a plentiful area. Going through my splits, Deb finds this beauty. A spot-check on some nearby rocks indicated that this particular area on the site might prove productive. Pictured here, after I removed the covering slab, is a very large dome. Domes at PD can either be full of trilobites or full of nothing. Paydirt! We finally found the productive part of the layer. Although none of these are complete, it is strongly indicative of the presence of more assemblages in the depositional environment. Of course, it was almost time for us to leave just when we found the sweet spot. But we did manage to pull out a few rollers and near-completes that I haven't had a chance to photograph yet, but I think I've got the real highlights here in this post anyway.
And so it was back to Canada after a four day adventure. I was beyond sore, of course, but overall it was great to collect with friends old and new, enjoy the outdoors, and come away with treasures found and gifted. Upcoming digs will likely be in the Arkona/Thedford area, and a trip to Bowmanville at the end of this month. Until then, time to manage some new backlog on the prep bench! Although I said in my last blog post that the next post would feature the big spring dig, a lovely gift came in the mail today courtesy of Tony, a Fossil Forum friend. I had won a "guess the number" contest and chose an ammonite as my prize. Well, he added two Cambrian trilobites to the box, because that is just the generous guy he is. The ammonite is from the Triassic of Nevada (possibly Frechites sp.). Let's have a closer look at the two ptychopariids... The ventral view of a nice Bythicheilus typicum. This is described as a "fast-moving low-level epifaunal deposit feeder." This is Bolaspidella reesae a lovely trilobite from the Wheeler Fm.
Ok, I promise the next post will be about the big dig. I just couldn't resist sharing this lovely gift. The snow has (only briefly, I hope) returned once again and it is coming close to May. I'm hoping this will be the last blast of winter... but I think I've said that before! The weather looks like it will turn around for the weekend and return to normal seasonal values. And that is great news as I gear up for a four day dig at three sites in NY next weekend with plenty of Fossil Forum folks. Speaking of Forum folks, one of our very generous members, Ralph, sent me a lovely package of trilobite partials he was able to pick up from a rock show. Ralph was also exceptionally kind in sending me (and several others) large boxes of Conasauga Fm matrix from Georgia, USA to play with, loaded with Cambrian trilobites. Pictured here are three species of trilobite new to my expanding collection (standing at a whopping 76 distinct species now). Let's zoom in... These are the pygidia of the Silurian phacopid, Trimerus delphinocephalus that occurs in the Rochester shale of NY. These trilobites are narrow and could grow quite large and somewhat resemble Dipleura dekayi in terms of shape. A nice assortment of partials of the dalmanatid, Dalmanites limulurus, also from the Silurian Rochester shale. These ones do not preserve very well, and many of the ones for sale are missing the cuticle and their eyes, with some people choosing to restore them by adding eyes from other partials to make a frankenbug. That is fine if the seller is honest about the restoration (not all sellers are, though). One remark about the Rochester shale trilobites is that they tend to appear as though "listing" in the rock, leaning to the right or left. Although missing some parts, this is another phacopid, Huntoniatonia sp. Without more diagnostic detail, drilling down to the species level may not be possible with this one. This one appears in the lower Devonian limestone of the Haragan Fm in Oklahoma, which is also famously known for producing some lovely spiny and horned trilobites like Kettneraspis and Dicranurus which usually only appear in Moroccan deposits. To some trilobite collectors, Oklahoma is like a little Morocco with the similarities between species, although with continental drift now thousands of kilometres apart from one another.
So, a lovely gift from Ralph once again keeps my spirits up while the weather is not cooperating fully with my digging plans. Recently I was able to get up to one of our sites in Ontario with collectors Kevin and Matt after some aborted attempts due to weather. Malcolm is due to join us next week for a 2-day trip. There is an incredible amount of work to do to get this site up to productive par. Winter saw the collapse of the upper erosion-resistant shelf, and as it tumbled it took a lot of overburden down with it, burying all of last year's benches. This is what the site looked like in January when I paid a short visit during a temporary thaw. To give a sense of scale (since I failed to do that in my haste taking this shot), those blocks are about 3-4 feet high. Up behind were the benches we had been steadily making last season, now buried. Last season was very good at our site once some of us were able to get down to one of the productive trilobite layers, and it was fairly common that a day's digging would mean going home with 2 or more full specimens. It was the result of many hands working those benches, expanding them, and getting at a layer that pulses here and there, pinching in and out. We arrived in the morning with our arsenal of tools, prepared to do a lot of site preparation work - shovels, picks, the entire spectrum of hammers. A picture of Kevin. At this point, Kevin and Matt had been able to open the bench back up a bit more after Malcolm had done some work the previous week. The problem is that we have lost our layer, and it is still uncertain if what is below our feet here is already exhausted (likely is), and so there is little choice but to bite deep into the cliff and work our way down. This is not as easy as it sounds: for every foot deep we need to expose, there are about 6 or more feet of overburden and shale blocks to remove - and this increases the deeper you need to bite into the slope. The other challenge is that a lot of these blocks are interlocking at various angles, and they need to be "unlocked" by removing key pieces as you follow a fault, some of which go on for a long time. It is not uncommon to think the fault will end only to find it wander in far and intersect with another fault that needs to be worked first, and maybe another one that jumps ahead in the sequence. What may look like a simple unlock of a slab and removal becomes complicated and even more labour intensive in a hurry. Matt and Kevin up at our bench. We put in a solid six hours of work to expand this, and we are not anywhere close to exposing enough to get this site productive again. As you can see above, there are three "hollows" that each of us worked. I worked the middle one where Kevin is sitting, spending all day on just one stubborn slab that was interlocked in four places and would simply not let go as there was no point at which it could be dug in and levered out. Some weathering will need to take place. We constantly bumped up against layers that where the matrix was dense and would simply shatter into shards rather than come out large and clean, leaving a messed up jagged face. If our tools cannot find a place to bite deep and gain purchase, the shale just chips off diagonally across the splitting plane. That set up for an agonizing game of inches, always in the hopes that we could find that right piece to unlock the shale puzzle. Fossils from these upper layers were of poorer quality, mostly. Very turbid, agitated deposition environments that gave up a lot of bits, or were otherwise just stuffed with brachiopods (which become a bit of a nuisance quickly). A few very thin nautiloids were spotted, but none of those nicely plump pyritized and ribbed ones. There were zero ammonoids apart from some traces of living chambers, which told me we were not quite yet at the layer we needed to be as those are heralds of coming close to the trilobite layer. Pyritized worm burrows, brachs, and trilo-bits dominated the rocks. We're still too high up in the strata, so we are still trying to dig in, and then down. We'll know when we hit that trilobite layer as they tend to congregate together. The general rule is if you find one complete, take it home and probe the matrix for more. As for the site itself, it is still going to take a few more long days to get it ready for the season. The tricky part is in planning the day so that we don't do all the excavation work in exposing the layer, have to leave at the end of the day, and someone else simply exhausting it without having done the grunt work required. But this site is nowhere near the point where that is in danger of happening. We also reason that we are coming close to this particular exposure having one last good season in it before it becomes untenable to work it anymore as we are losing the slope, and would probably have to work down 20+ feet of rock from the top to create new benches. Each of us came away with 3 or so potential full ones, mostly damaged. These are the isolated full ones you can expect to encounter in the bits and pieces layers, and their preservation is generally quite poor (and they are flaky and delicate to begin with). Here is one of mine missing the the left part of the cephalon and the anterior portion of the glabella. A prep practice piece, or fodder for reconstruction parts. In all, the trip was all about site preparation, not so much fossil finding. That will come, but only after we put in quite a few more days of heavy digging, hammering, and hauling. It was fantastic to work alongside Kevin and Matt, as they are a great and hilarious bunch of guys. When we trudged back to the cars at the end of the day, Kevin set me up with an Isotelus "mafritzae" that he expertly prepared. Kevin prepares and sells trilobites almost exclusively to high end clients, and this trilobite here - as top shelf as it is - is hardly representative of the gorgeous pieces he finds and prepares.
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Kane Faucher
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February 2024
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