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The brachiopod Isogramma Meek and Worthen (1870) is challenging to identify when found by inexperienced collectors. These fossils appear as a half circle of sharp, equal-spaced concentric growth lines. All specimens appear flattened, making them difficult to identify as dimensional brachiopod shells. The shells are concavo-convex in life, but dueRead More →

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Update: This is not a monospecific/monotypic genus. Some additional species are recently described in the mid-continent. I will add the references when I get time. The monospecific genus Pennoceras has a limited range, the Brush Creek and Pine Creek limestones in Pennsylvania and Ohio. These curious members of the GoniatitidaRead More →