Holocystites scutellatus cystoid
This trip to Napoleon, IN featured a visit to the New Point Stone quarry on Rt. 48 a few miles east of Napoleon. The quarry is currently closed to collecting. This quarry exposes rocks of Silurian age (Brassfield Dolomite, Osgood formation, Laurel Dolomite). The Brassfield is the base of the Silurian in this quarry. Of particular interest is the Upper half of the Osgood formation, which is fossiliferous in and around Ripley County, IN (where the Brassfield formation is thinned or even absent). This "Ripley Island" effect, is somewhat of a mystery because the Osgood formation is devoid of fossils outside of this area. The prizes to find in the wall debris, spoil piles, and ramps made from Osgood shale are the well preserved Silurian cystoids. They are not abundant, but in just two trips, club members have found at least 4 different types of cystoid (2 species of Holocystities, a Caryocrinities, and a giant Triamara). In addition, other Silurian fossils can be found such as: Atrypa brachiopod, Dawsenoceras cephalopod, bryozoans, a few gastropods, crinoid stems, a few crinoid calyxes, nice pyrite cubes in shale, and some Bumastus trilobite pieces.
A popular trip for the KPS is in Owingsville. On I-64, take exit 121 and go to the Dairy Queen. Behind them is an excavation with the most beautifully preserved Hebertella brachiopods to be found anywhere. It is the upper Ordovician Bull Fork Formation. In addition, other fossils to be found are bryozoans, occasional gastropods, rare edrioasteroids, stromatoporoids, and Tetradium coral.
On I-64 near Owingsville, there is a roadcut which exposes a flat area of Silurian Brassfield Formation. This is the base of the Silurian in this area. In fact, the Ordovician-Silurian contact can be seen at this roadcut. Uncommon echinoderm fossils can be found here (very sparse), along with horn corals. A starfish and one or two small cystoids have been found. More common are small cystoid anchors less than a quarter inch in size. They look like little white cups. A partial crushed glyptocystitid (cystoid) calyx was found that showed the "pectinirhomb" structure used for respiration. It looks like a mini crescent-shaped radiator grill.
A popular KPS field trip is to Olive Hill, where the Ken-Mor stone quarry resides. With permission, the KPS has collected in the Mississippian Haney formation in the quarry. Climbing up huge piles of rock reveal weathered out beautiful pink-to-garnet colored blastoids (Pentremites) and huge brachiopods (some with Cornulites worm tubes). Other fossils found include shark's teeth, crinoids, an edrioasteroid, and uncommon disarticulated echinoids (sea urchins).
On a separate trip, some road cuts within 20 miles west of Olive Hill on I-64 were explored. Some interesting Mississippian crinoid calyxes were found in the Borden Formation (Nada member), and a large (9 cm) shell-crushing shark's tooth was found in the Haney Formation (probably Psammodus sp.). There are two distinct layers in this tooth. The top layer is white and porous, while the bottom layer is dark blue/gray.
On the Gene Snyder freeway, the Mississippian Borden formation (New Providence member) is exposed. At one particular exit ramp, beautiful 3-dimensional Conularia can be found in nodules. Other fossils include gastropods. Collecting of Ordovician, Silurian and Devonian fossils is also possible in this area.
On a roadcut a few miles north of Hopkinsville, Mississippian Chesterian rock is exposed. On one cut, there is a massive oolitic limestone layer which overlies a heavily weathering shale. Two species of Pentremites blastoid can be picked right out of the shale. One slab was found with over a dozen blastoids embedded on the surface. A few can be over 0.75 inches in size, but most are a half inch or less. A majority are uncrushed and are preserved as a tan colored calcite. A good percentage of the blastoids found at this cut have an unfamiliar feature at the base of each ambulacra. It looks like a small stem-like growth attached to the U-shaped radial plate. In addition, one blastoid was found with what looks very much like a predatory bore hole in one of the plates. Other fossils found at this site include a few brachiopods, Archimedes bryozoans, and a trilobite pygidium. Blastoids are the most prevalent fossils.