The long October weekend is here, and despite it raining this morning, I was able to get out yesterday and have plans to make a few visits to my Bois Blanc Formation rubble between bouts of turkey and getting caught up with essay grading. The number of rocks that are highly fossiliferous is dwindling, but I'll have enough to see out the rest of this year. This small haul of trilobite partials would be considered a fairly good outing: three fragments of Acanthopyge contusa and two fairly preserved pygidia of Crassiproetus crassimarginata. That brings my total Acanthopyge fragment count to about 9, and 13 lichids overall. If I could only find a complete example, I could stop collecting the fragments. As the material is very rostroconch-dominant, I only pick up the odd one on occasion if they look nice. I hope to get out a few more times in the next while and update this post if more neat finds are made. So, to be continued... Saturday Update So another four hours out back, and I didn't do too poorly. It took me a bit longer of trial and error to find the right productive rock, and it was this one rock -- and only this rock -- that produced the days finds. I suspect this to be another lichid genal spine (possibly Acanthopyge contusa). Left: negative and positive. Right: closeup. Just missing its cheeks, an otherwise complete Pseudodechenella sp. None too shabby! This would be the day's best. Perhaps I'll have another go tomorrow. Sunday update Well, it was a challenge to find more productive rocks to split. Four hours, and not much to show for it. In fact, it was the first visit in some while where I didn't even find a trace of a lichid. But sometimes a small find can be just as rewarding. This looks very much like a Mystrocephala stummi to me (compare with the image from Ludvigsen on the right). If so, that would make a new species find for me. Although the pygidium axial width is not 1/3 or more of the entire pygidial width, I can make out the little nodules along the heavily incised pygidial ribs. Of course, the fact that it is only reported in the Formosa reef (Amherstburg Fm) possibly problematizes the assigning of this rock to the Bois Blanc, but so did the appearance of Acanthopyge contusa. There's trilobites from both formations here, sometimes on the same bedding plane. Perhaps another visit tomorrow? For now, round 1 of turkey. Monday update Five hours and I've pretty much managed to tap out a section of much of the viable rock. It wasn't until the last half hour that I was able to find anything at all, with much of the time spent splitting duds, blanks, bits, and other false leads. If the fourth of four sections has any viable rocks left, they are massive armour stone boulders that even I can't either move or do more than splinter/fracture the edges. So on I moved to section two. As with a lot of the lichids in this material, the preservation is generally poor, but this Acanthopyge contusa positive and negative is still fairly articulated with the course tubercles and delineated goblet-like pygidium axis. That brings me to 15 lichid fragments, with eleven of those from this species. I probably have more examples of this species than any museum. Once more into the breach before I give the site a rest for a bit. My focus tomorrow will be a return to section two. There's still some source rock to go through from where I obtained this pygidium. If time and energy permit, I might poke around section one (fairly tapped out) and section three (mostly blank or lenticular coral limestone + domes). I've put in 16 hours in 4 days. Tuesday update And another five hours in the proverbial hole, and that will be all for now as I need to get back to much-neglected work. But on to the finds that close out these five days of persistence. Yes, it's yet another Acanthopyge contusa. Although the photo doesn't do it much justice, this is a very nicely preserved cranidium despite missing a lobe on the right. The tubercles are nice and clearly defined. The trip-maker? What appears to be a cranidium that compares favourably to Terataspis grandis. Image on the right is from Ludvigsen's text. But, sadly, it is just another Acanthopyge. Here is the same specimen in sunlight, and the negative below. So, the final tally:
5 days (21 hours) 12 Trilobites (7 lichids, 4 proetids) = 7 Acanthopyge contusa, 2 Pseudodechenella sp. (one almost complete), 2 Crassiproetus crassimarginatus, 1 Mystrocephala stummi Not bad at all. Spending all this time out there has forced me to revise assumptions about this material, and it may be a blend of Bois Blanc, Amherstburg, and Lucas Fms. Not sure when I'll be going back, but my hammering arm needs a break! Comments are closed.
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Kane Faucher
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February 2024
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