Keeping closer to home, I've managed to pull some interesting if not typical specimens from the Dundee Formation along the Thames River. I even found a pitifully small trilobite pygidium (really not worth showing). The more visually interesting specimens happen to be coral, a few brachiopods, and bivalves. Unless otherwise indicated, these are all from the Dundee Formation, of the Devonian age, Eifelian stage. Not shown in these images were the plentiful and more robustly ribbed Brevispirifer lucasensis. So, let's show rather than tell: A fairly well-preserved chunk of colonial coral (?Favosites sp.). I don't usually go in for coral, but this one was a must-have. Another busy hash-plate containing some rugose corals (?Zaphrentis sp.), a brachiopod (Rhipodomella sp.) and a bryozoan (Fenestella sp.). Now that I'm back on campus teaching again, I took a few more pictures of the fossils in the wall of the Visual Arts Centre. The picture above already appears in my pre-blog entry, and I had misidentified it as a coral rather than a sponge (although it is nicknamed a "sunflower coral" due to its resemblance to a sunflower). It is a Fisherites ?occidentalis (formerly Receptaculites occidentalis, Blainville 1830, genus changed in 1979, Finney & Nitecki). The building's composition is Tyndall Stone (trademark of Gillis Quarries), Ordovician in age (Maysvillian stage), in the Selkirk Member of the Red River Formation quarried in Manitoba - incidentally the same material used in the Parliament Building. It is a dolomitic limestone mottled by many corals and thalassinoides. Another image of the same limestone sporting two fairly large nautiloids side by side, siphuncle showing in the specimen on the right. There are also several large gastropods if you take the time to scan the exterior of the building. And here is one such gastropod, Hormotoma sp.
The mottling of this limestone was a bit of a puzzle for some while. The mottling is something of enormous interest for the ichnologist (study of fossil burrows and traces). Here are some helpful papers on the subject: Kendall, A.C., 1977. Origin of dolomite mottling in Ordovician limestones from Saskatchewan and Manitoba. Bulletin of Canadian Petroleum Geology, v. 25, p. 480-504. Myrow, P.M., 1995. Thalassinoides and the enigma of early Paleozoic open-framework burrow systems. Palaios, v. 10, p. 58-74. (PDF) Sheehan, P.M. and Schiefelbein, D.R.J., 1984. The trace fossil Thalassinoides from the Upper Ordovician of the eastern Great Basin: deep burrowing in the early Paleozoic. Journal of Paleontology, v. 58, p. 440-447. -- And that is all from me for now. I'll be heading back to the Penn Dixie site in early October, now as a new and proud member of the Hamburg Natural History Society, for a two day dig. Comments are closed.
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Kane Faucher
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February 2024
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