It's been almost three weeks since I've been out collecting, and something I hope to rectify soon with a local trip tomorrow, a less local trip on Sunday, and then some spots in much farther areas next week. A few plans fell through, so some of the sites I wanted to visit may have to wait until next season. So to break up the long silence, why not post about an older trip? I've done a few visits to the north of the province, with a focus on encrinurids. Some good finds were had, and I won't post them all. Although just a fragment, no less exciting. A partial pygidium of Ekwanoscutellum cf. ekwanensis. This is a ventral example. The fine ornamentation on the shell can be seen here. Finding even a whisper of these is a very rare treat in this material. Weathered surface specimen, but still an interesting one. This one is not the typical Rielaspis cf. elegantulus, but likely some form of Encrinurus sp. Again, just a fragment but the only example of Diacalymene found in this material. I've likely posted these before. A Rielaspis without its cheeks (far more common to find), and one with both cheeks and eyes -- with the added bonus of being completely free from matrix. This one popped off while I was preparing it and thankfully stayed intact! The next is what I would call the prize find. A friend of mine is preparing it and it is not fully done yet. As found. Four individuals showing. Very preliminary prep. Five individuals showing. Where it is so far. Twelve(!) individuals showing. If you can spot it, there is also a tiny crinoid on the plate. As this was found in a tumbled pile, attempts to locate the missing pieces came to naught. Although a number of these are incomplete or disarticulated, it is no less a nice looking plate. The work on the ventral examples is quite lovely, and at least three specimens have both cheeks (so far).
As far as updates, I had to cry uncle over that giant Isotelus, and it is now in the hands of a skilled preparator. And hopefully in the coming week I'll be messing around in the Ordovician again. The soggy July is giving way to the hot and hazy dog days of summer. I've only done two site visits in a day since returning from Quebec (both local, both quickly crossed off the list). I am sure there are some good, faraway trips to be had this summer before a return to campus. Thankfully, I have some material to prepare to keep me busy. First success at the bench is this giant Flexicalymene senaria. This species is ridiculously common in the strata of Ontario (Verulam, Bobcaygeon Fms) and Quebec (Neuville Fm), but not weighing in at 5+cm (2 inches) long. Despite some damage to a few of the posterior axial rings, this is still at least a 500 dollar bug on account of its size. In terms of preparation, it was not overly difficult or time consuming. A baby Ceraurus pleurexanthemus. This one measures about 7 mm long. I've done just enough prep to establish it has both genals and pygidial spines, but will not proceed any further with my current equipment as the fine details require something like a Comco or Crystal Mark abrasive unit. Doing so with my Paasche will just ruin it, so to the side it will sit for now. The other prep was this crinoid that I've roughed out. A monster project with a monster bug. This semi-enrolled Isotelus gigas is a true giant that I estimate will likely measure 9 inches around judging by the width of the axial rings (currently being exposed) at about a centimetre each. This one was covered by over three inches of dense limestone, and the rock itself is riddled with cracks. This means very slow scribing with frequent breaks to stabilize the cracks and fortify the very thin axial ring shell. Once I can free the whole thing, I will be doing some restoration work. Finding a complete one in Quebec is certainly rare, but to find one this large is well beyond that. I'll update this entry once I get more done. I reason this will take about 50-100 hours to do it well. UPDATE: July 5/6: Updating progress as I go. At this (messy) stage, it looks worse than it actually is. Pardon the caked dust. The photo fails to show the depth of the "hole" I'm working in. Scribing and grinding three or more inches deep of matrix is a long process, and one that I am just now decreasing with the aid of a Dremel with a diamond wheel to score cross-hatch cuts. This is going to save a lot of time. I'm just now at the anterior of the cephalon, with a goal to follow it to the tip, and then work laterally to gradually expose the eyes and cheeks. I'll also be freeing up the bulk remainder of the thorax before switching to a finer scribe for detailing, and finally air abrasion on the more delicate areas. The absolute final stage will involve some restoration of missing bits. What this photo also fails to show is how the cephalon is dipping into the rock at about a 45 degree angle.
UPDATE: July 11 After an on and off again week, about 20-30 hours was spent on the trilobite. Compared to a week earlier, a lot of material has been removed to reveal the majority of the axis, right pleurae, and some of the very fragile/fractured left pleurae. The cephalon is revealed, up to the palpebral lobe, and I am fishing out the anterior of the glabella. The genals/cheeks are mostly uncovered, but more work on the left is required. I am leaving the matrix "ridges" near the axis for finer scribing later. What the photo does not convey is the depth of the relief and matrix as the cephalon tucks down along the curvature of the enrollment.
The mottled white areas are where stabilizing glue has dried (mixed with a bit of dust), which will be abraded off along with some of the finer area matrix after the whole trilobite is roughed out using the scribes. There is still a lot of matrix to remove. The cheeks tuck in, and for additional challenge appear to "step down" from a crack in the shell. The measurement from genal to genal is roughly 5 inches. Using the ratios supplied by Rudkin and Tripp (1989) that compared 56 of the most complete Isotelus gigas in repository, the width of the cephalon corresponds to an average of 43% of the complete dorsal shell (sag.). Should that ratio hold, then the entire specimen would likely be over 11 inches (>279 mm). Back to work... |
Kane Faucher
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