The oldest Archimedes fossils reported in Kentucky are from the Middle Mississippian Borden Formation, and they range through the uppermost Mississippian strata preserved in Kentucky. National Museum collection (Conkin and Fuson, 1970). One species, found in the Mississippian Floyds Knob Bed of the Borden Formation, in Marion and Jefferson Counties, is called Archimedes kentuckiensis. Some of the specimens he studied are in the Department of Earth and Environmental Sciences’ paleontological collection. McFarlan, a professor in the geology department (now the Department of Earth and Environmental Sciences) at the University of Kentucky, and past state geologist and director of the Kentucky Geological Survey. Many species names were defined by Arthur C. Most of the species names assigned to Archimedes axial columns are based on variations in the shape of the convolutions (coils) and spacing of convolutions (McFarlan, 1942 Condra and Elias, 1944). Both the coiled axes and fronds may have species names (McFarlan, 1942 Bassler, 1953). At least 16 species of Archimedes, several with multiple varieties, have been reported from Kentucky (Butts, 1917 McFarlan, 1942 Conkin and Fuson, 1970 Chesnut and Ettensohn, 1988 Sable and Dever, 1990). Archimedes structures appear to have been fragile and easily broken therefore, whole three-dimensional fossils with complete fronds attached to axes are rare In addition to Archimedes frond genera, some species of the frond genera Fenestella and Fenestellina also are found attached to Archimedes support columns (although not all of the species of these genera were coiled and associated with Archimedes).
Most are a few millimeters wide and two to three centimeters in length, although longer columns are sometimes found. The genus name Archimedes is most commonly used to describe a corkscrew-shaped, bryozoan axial support column, although attached fronds are also defined under the genus. Fans and fronds were mesh-like-perforated by tiny holes.ĭescription. Fenestrates are a type of bryozoan that had fan- and frond-shaped colonies. Bryozoan structures look similar to the types of colonial structures built by corals, but they are a distinctly different phylum of organisms. Different types of prehistoric bryozoa built colonial mounds, branching bushes, crusts, and fan- or frond-like structures. They are tiny (less than 1 millimeter long) organisms that construct colonial structures. The fossils are named after the Greek scientist and philosopher Archimedes, who designed a corkscrew-shaped irrigation pump.īryozoa are a phylum of marine invertebrate organisms that still live today. Broken fragments of Archimedes are common in Mississippian rocks of both eastern and western Kentucky. It is a genus of fenestrate bryozoans, defined by a corkscrew-shaped axial support column and spiraling mesh-like fronds attached to the column. Kentucky Geological Survey paleontological collection.Īrchimedes is a fossil that looks like a screw. Found in Grayson County, possibly from the Glen Dean Limestone. Collection of loose, screw-shaped bryozoan fossils Archimedes.
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