It is that time of year when the fossil weather is not too hot nor too cold. I took the opportunity to forsake Thanksgiving festivities to go out in the field, bothering the Bobcaygeon Fm. It started out with a bit of a bang. A nice cluster plate of Ceraurus globulobatis and at least one ventral Gabriceraurus dentatus. A lot of pieces need to be reattached, and there is the possibility that more may be lurking under the matrix. I found this within a half hour, so that somewhat set the tone for the weekend. There is one very nice specimen in the mix, and the rest we'll just have to see what prep shows. A severely exfoliated Calyptaulax callicephalus and the pygidial spines of a cheirurid (likely Ceraurinus marginatus). Although I did encounter a few Calyptaulax on this trip, none of them were really worth bringing home. Heartbreaker ventral Gabriceraurus of healthy size. Despite much care (and glue), this one did not survive extraction. On the right is mostly the impression of a Failleana indeterminata; I did not find even a whisper of this styginid beyond this. The phantoms of Ceraurus, and what I suspect is a Ceraurinella ("Xylabion") on the right. Just impressions, sadly. Either the pygidium is gone, or likely tucked flat sandwich-style underneath on the left Ceraurus, and on the right an enrolled example. It isn't the Ordovician of Ontario without some Flexicalymene senaria. Scrappy examples, maybe worth a quick clean. Pygidium of Ectenaspis homanolotoides, which are fairly rare asaphids. On the right is one of the better examples of Raymondites I found. It is tough to believe, but for my many weeks in the Ordovician of Ontario, I had never managed to find a complete Bumastoides milleri. Sure, plenty of parts, and even complete thoracopygons, but this trip finally crossed that off the list. Photo on the right is just a quick ten minute scribing to expose a bit more before the official prep can reveal this one in its more robust glory. The cephalon is a bit crushed, so not a top shelf bug. A Carabocrinus vincourtlandti complete calyx, and possibly a smaller example on the upper left. Echinoderms are not really my thing, but I will pick them up if they are interesting. Prep will be needed to see if the stout arms are on these. The classic Pleurocystites squamosa. A scrappy example, but the nicer ones refused safe extraction, so this was my consolation prize. The wispy tail is present, but mostly buried under the matrix. A ventral asaphid of about 11-12 cm. Obviously, extraction is going to be tricky business. I used up the last of my glue to stabilize it as best as possible before delicately and slowly using hammer and chisel at key points in the rock to minimize damage. The long diagonal crack shown here runs very deep, so there is no choice but to take it out (carefully!) in two pieces to be glued back together later. Much glue is used to prevent pieces of shell from flying off. Success. Ventral and dorsal views. This is going to be one heck of a prep job requiring much paraloid to stabilize the ventral area. Those pleurae are hanging out matrix-free in the open. I also kept the negative which has the left eye. Although there is not yet agreement between me and my fossil comrade, I am thinking it is an Ectenaspis. It seems a bit too elongated to be a typical Isotelus gigas (looks more like Isotelus "mafritze", but those do not occur in the Bobcaygeon). The one way to determine this beyond a shadow of a doubt is to see if there is that classic projection on the pygidium, which is still mostly buried here. If so, then this is truly the trip-maker.
I have a few other specimens that need to be pieced back together, and photographed. In all, not a bad trip. Despite the surplus of trilobites here, the material is fickle in both preservation and abundance, so requires a lot of time scanning slowly with care. I do hope to get out one more time in early November, assuming weather and opportunity cooperates (coinciding with Reading Week, as otherwise I'm doing the teaching thing). As the weather cools, some of these specimens will be making their rounds in my prep area, so at least I have a few more winter projects to share. Comments are closed.
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Kane Faucher
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February 2024
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