The Ordovician Period spanned approximately 505–438 million years ago during the Paleozoic Era. It was defined by Charles Lapworth in 1879 and is named for a Welsh tribe, the Ordovices. In Kentucky, southeast Indiana, and southwest Ohio, the Upper Ordovician is called the Cincinnatian and is the main study area of this age in the Americas. These rocks are about 458–438 million years old.

On the eastern side of Louisville / Jefferson County, Ordovician fossils can be found in road cuts and creek beds. Central Kentucky (around Lexington) exposes Middle Ordovician rocks from roughly 468–458 million years ago.

For an overview of Upper Ordovician rock types in the region, see the lithostratigraphic summary here: http://www.uga.edu/strata/cincy/strata/LithostratOverview.html .

You can learn more about Upper Ordovician rocks and bryozoans in the classic work The Upper Ordovician Rocks of Kentucky and their Bryozoa, restored by the Kentucky Paleontological Society, available at: http://www.uky.edu/OtherOrgs/KPS/books/nickels/nickels1905.htm .

Additional excellent resources on Ordovician fossils can be found at the Dry Dredgers of Cincinnati, Ohio: http://www.drydredgers.org .

Scroll down this page and select the name of a particular fossil to view its image on a separate page. Use your browser’s Back button to return here after viewing an image. Some images may be larger than your screen resolution; click on the image to expand it.

Brachiopods

• Hiscobeccus capax (Conrad), Grant Lake Formation, Taylorsville Lake, Spencer Co., KY
• Leptaena richmondensis, Ordovician, KY
• Petrocrania scabiosa (Hall), inarticulate brachiopod on Rafinesquina, Ordovician, KY
• Philhedra laelia (Hall), encrusting bryozoan, Upper Ordovician, Fairmount Formation, Gallatin Co., KY
• Platystrophia clarksvillensis, Ordovician, KY
• Platystrophia ponderosa Ulrich, Ordovician, KY
• Platystrophia ponderosa Ulrich, McMillan Formation, Spencer Co., KY
• Rafinesquina ponderosa Ulrich, with inarticulate brachiopod Petrocrania scabiosa (Hall), Fairmount Formation, Gallatin Co., KY
• Rafinesquina ponderosa Ulrich, Ordovician, KY
• Retrorostra carleyi (Hall), Upper Ordovician, index fossil for Arnheim Formation, Madison, Jefferson Co., IN
• Strophomena nutans Meek, Ordovician, KY
• Trematis millipunctata (Hall), Grant Lake Formation, Taylorsville, Spencer Co., KY; Falls of the Ohio State Park collection
• Zygospira modesta, Ordovician, KY

Bryozoans (Moss Animals)

• Constellaria sp., genus characterized by star-shaped monticules, Upper Ordovician, Kope Formation, Carrollton, Carroll Co., KY
• Cuffeyella arachnoidea (Hall), Grant Lake Formation, Taylorsville Lake, Spencer Co., KY
• Dekayia ulrichia (Nicholson), Upper Ordovician, Kope Formation, Jefferson Co., IN
• Heterotrypa subfrondosa (Cumings), Upper Ordovician, Fairmount Formation, Carroll Co., KY
• Homotrypa dawsoni (Ulrich), Upper Ordovician, Waynesville Formation, Madison, Jefferson Co., IN
• Monticulipora mammulata (d’Orbigny), McMillan Formation, Hwy 127, Owenton, Owen Co., KY
• Monticulipora mammulata (d’Orbigny), encrusting a Rafinesquina brachiopod, Upper Ordovician, Fairview Formation, Gallatin Co., KY
• Monticulipora mammulata (d’Orbigny), Ordovician, KY
• Parvohallopora dalei (Milne-Edwards & Haime), Upper Ordovician, Fairview Formation, Jefferson Co., IN
• Parvohallopora onealli (James), part of a collapsed colony nearly a meter wide, Upper Ordovician, Kope Formation, Worthville, Carroll Co., KY
• Praspora simulatrix (Ulrich), Lexington Limestone (Jessamine Formation), Frankfort, Franklin Co., KY
• Unknown bryozoan, Middle Ordovician, Cynthiana Limestone, Scott Co., KY
• Unknown bryozoan, Upper Ordovician, Kope Formation, Carroll Co., KY

Cephalopods (Mollusca)

• Charactoceras, Ordovician, Arnheim Formation, Mt. Orab, OH
• Orthocerid cephalopod, with a grid-like external shell pattern (rarely preserved due to fragile microstructure), Upper Ordovician, Kope Formation, Carrollton, Carroll Co., KY
• Orthocerid cephalopod, shell lines preserved by encasing Spatiopora? sp. bryozoan, Upper Ordovician, Kope Formation, Carrollton, Carroll Co., KY
• Orthonybyoceras, cut to show diagnostic features, Ordovician, KY
• Treptoceras, cut to show diagnostic features, Ordovician, KY
• Unidentified orthocone, Upper Ordovician, Bull Fork Formation, Springfield, Washington Co., KY
• Unidentified orthocone and Cyclonema sp. gastropods, Upper Ordovician, river alluvium, Falls of the Ohio State Park collection
• Unidentified orthocone, Upper Ordovician, Kope Formation, Worthville, Carroll Co., KY

Clams (Pelecypods / Mollusca)

• Ambonychia robusta Miller, Grant Lake Formation, Taylorsville Lake, Spencer Co., KY
• Ambonychia robusta (or possibly Anomalodonta gigantea Miller), Ordovician, KY
• Caritodens demissa (Conrad), Upper Ordovician, Arnheim Formation, Madison, Jefferson Co., IN
• Deceptrix filistriata (Ulrich), one side shows the dentition, Upper Ordovician, Kope Formation, Carrollton, Carroll Co., KY
• Ischyrodonta elongata, Ordovician, KY
• Lyrodesma conradi Ulrich – shows teeth and dentition; muscle scars are obscured, Upper Ordovician, Kope Formation, Carrollton, Carroll Co., KY
• Modiolodon sp., Upper Ordovician, Grant Lake Formation, Taylorsville Lake, Spencer Co., KY
• Modiolopsis sp., Upper Ordovician, Grant Lake Formation, Taylorsville Lake, Spencer Co., KY

Corals (Cnidaria)

• Calapoecia sp., Ordovician, KY
• Cyathophylloides cf. C. burksae, Upper Ordovician, Drakes Formation, Bardstown Member, Jefferson Co., KY
• Grewingkia canadensis (Billings), borings possibly made by Trypanites weisi (Mägdefrau), Upper Ordovician, Drakes Formation, Bardstown Member, Jeffersontown, Jefferson Co., KY
• Grewingkia rusticum (Billings), Liberty Formation, Middletown, KY
• Foerstiphyllum vacuum? (Foerste), Ordovician, KY
• Foerstephyllum vacuum (Foerste), Upper Ordovician, Drakes Formation, Taylorsville Lake, Spencer Co., KY
• Protarea richmondensis Foerste, with horn coral Streptelasma divarcans Nicholson, Liberty Formation, Madison, Jefferson Co., IN
• Saffordophyllum? Foerste, Ordovician, KY

Crinoids (Echinodermata)

• Crinoid holdfasts on bryozoan, Eden Formation, McMicken Member, Carrollton, Carroll Co., KY
• Lichenocrinus sp., holdfast for Cincinnaticrinus, Upper Ordovician, Kope Formation, Carroll Co., KY
• Podolithus, crinoid holdfast attached to Dekayia bryozoan branch, Upper Ordovician, Kope Formation, Carrollton, Carroll Co., KY

Cyclocystoidea (Echinodermata)

• Cyclocystoid, Shelby Co., KY
• Unidentified cyclocystoid, very rare fossil, Grant Lake Formation, Taylorsville, Spencer Co., KY; Falls of the Ohio State Park collection

Edrioasteroidea (Disk Stars) & Asteroidea (Sea Stars)

• Carynella sp., on Rafinesquina ponderosa Ulrich with a second edrioasteroid Cystaster sp. and multiple inarticulate brachiopods Petrocrania scabiosa (Hall), Upper Ordovician, Maysville Group, Covington, Kenton Co., KY
• Carynella sp., Maysville Group, Covington, Kenton Co., KY
• Salteraster grandis (Meek), formerly Urasterella, Upper Ordovician, Arnheim Formation, Madison, Jefferson Co., IN

Snails (Gastropoda / Mollusca)

• Clathrospira sp., Ordovician, KY
• Clathrospira sp., Ordovician, KY
• Cyrtolites (Paracryptolites) carinatus (Miller), monoplacophoran, Upper Ordovician, Kope Formation, Carrollton, Carroll Co., KY
• Cyclonema bilix, Ordovician, KY
• Lioclema micula (Hall), Upper Ordovician, Kope Formation, Carrollton, Carroll Co., KY
• Liospira, steinkern, Upper Ordovician, Kope Formation, Carrollton, Carroll Co., KY
• Loxoplocus bowdeni (Safford) (genus later revised to Paupospira), Ordovician, KY
• Salpingostoma sp., Upper Ordovician, Grant Lake Formation, Nelson Co., KY
• Sinuites sp., monoplacophoran, Ordovician, KY
• Sinuites sp., monoplacophoran – note the “V”-shaped slit, rarely preserved, most are steinkerns, Upper Ordovician, Kope Formation, Carrollton, Carroll Co., KY

Sponges (Porifera)

• Auloceras undulata (Billings), Drakes Formation, Spencer Co., KY
• Dystactospongia madisonensis Foerste, Upper Ordovician, Whitewater Formation, “Madison Reef,” Madison, Jefferson Co., IN
• Heterospongia? sp. Upper Ordovician, Bull Fork Formation, Springfield, Washington Co., KY
• Heterospongia? sp. Upper Ordovician, Whitewater Formation, “Madison Reef,” Madison, Jefferson Co., IN
• Labechia huronensis, stromatoporoid, Ordovician, KY

Trace Fossils

• Bifungites, Waynesville Formation, China, Jefferson Co., IN
• Bryozoan bored with Catellocaulis vallata (Palmer & Wilson), Upper Ordovician, Kope Formation, Carrollton, Carroll Co., KY. Catellocaulis is thought to represent some sort of maturation chamber.
• Chondrites, dendritic feeding traces in sediment, Upper Ordovician, Kope Formation, Carrollton, Carroll Co., KY
• Sanctum laurentiensis Erickson & Bouchart in the bryozoan Peronopora vera Ulrich, Upper Ordovician, Kope Formation, Carrollton, Carroll Co., KY

Trilobites (Arthropoda)

• Cryptolithus bellus (Ulrich), KYANA field trip May 2008, Southgate Member, Eden Formation, Worthville, Carroll Co., KY
• Cryptolithus bellus (Ulrich), Southgate Member, Eden Formation, Washington Co., KY
• Flexicalymene granulosa (Foerste), enrolled specimen, Upper Ordovician, Kope Formation, Carroll Co., KY
• Flexicalymene meeki (Foerste), enrolled, Upper Ordovician, Waynesville Formation, Monroe, OH
• Isotelus brachycephalus Foerste, Arnheim Formation, Mt. Orab, Brown Co., OH
• Isotelus maximus (Locke), Grant Lake Formation, Taylorsville Lake Road, Spencer Co., KY
• Isotelus sp., Middle Ordovician, Lexington Limestone, Bluegrass Parkway, Woodford Co., KY

Other Fossils

• Cornulites, annelid worm tubes, Upper Ordovician, Kope Formation, Carrollton, Carroll Co., KY
• Geniculograptus typicalis (Hall), slab covered with carbonized fragments, Upper Ordovician, Kope Formation, Carrollton, Carroll Co., KY
• Leperditella, Hitz Limestone, Sleepy Hollow, Oldham Co., KY
• Sphenothallus sp., thought by some paleontologists to be a tube worm, Upper Ordovician, Bull Fork Formation, Springfield, Washington Co., KY; Falls of the Ohio State Park collection

A Note About Fossil Names

Fossils are named like other biological species. The genus and trivial name (for example, Auloceras + undulata) together form the species name. The author’s name is placed in parentheses (e.g., “(Billings)”) if the genus has been changed since the original description; it is not in parentheses if the genus is the original designation, as in Favosites niagarensis Hall.

A subgenus may be written as Favosites (Emmonsia) emmonsi Rominger, where Emmonsia is the subgenus. This taxon was originally described as its own genus but has since been folded back into Favosites. If the species is not known, “sp.” is used after the genus name (for example, Cyclonema sp.).

Names of fossils are often in flux, reflecting ongoing research. We strive to use the most up-to-date names available for the specimens illustrated on this site.

Abbreviations

Common abbreviations used in locality information include: Co. for County, KY for Kentucky, IN for Indiana, OH for Ohio, and TN for Tennessee.

Fossil drawings © Michael Popp, 2009.