| Comment: | This is the most paleontologically significant collection in the shipment. All but one of the collecting bags contain a single fauna dominated by numerous individuals of the genus Corynexochus, rare specimens of Olenaspella evansi Kobayashi, a species of Pseudagnostus, and indeterminate specimens of a lonchocephalid and a pterocephalid trilobite. One piece contained a remarkable branching object that is posibly an early graptolite. The insoluble residue was a gold mine of unusual objects including well preserved "spicules" of the genus Chancelloria, specimens of Hyolithes including operculae, at least five species of phosphatic brachiopods and a couple of bivalved conchostracans. Among the phosphatic brachiopods is a species of Acrothele, two referable to Angultreta, a distinctive paterinid, and a most unusual linguloid with a pedicle tube instead of a slot in the pedicle valve. Corynexochus is a distinctive small trilobite known from the early Upper Cambrian of northwestern Europe, Siberia, and Australia, but this is the first record of the genus in western North America. It comes from a stratigraphic position equivalent to the Dunderbergia zone or slightly older beds in the Dresbach stage. I have seen a linguloid with a pedicle tube in only two other collections, both from Australia. One of these also contained a species of Corynexochus!! Acrothele is a genus generally believed to be restricted to the Middle Cambrian, however, I have seen it once befor in an Upper Cambrian collection -- also from Australia. The Hyolithes operculum is not definitive stratigraphically as far as far as we know, but I have seen specimens in insoluble residues only once before, in a collection from the Dunderbergia zone in Nevada. This collection is certainly much older than any of the collections from the upper part of unit 6 in the Chief Mountain area, and is very probably from a unit entirely older than your unit 6 although I would like to see more material from the bottom of unit 6 to be sure. It is from a much younger unit than the one with collection 61AMc911 (3715-CO), however. |