Cannon Falls (Ordovician of the United States)

Where: Minnesota (44.5° N, 92.9° W: paleocoordinates 19.6° S, 70.9° W)

• outcrop-level geographic resolution

When: Shakopee Formation, Cassinian (478.6 - 468.1 Ma)

• AGE: Cassinian; refined by A. Hendy (6/2009) on the basis of biostratigraphic data.

• bed-level stratigraphic resolution

Environment/lithology: lithified, dolomitic, ooidal, gray, cherty/siliceous limestone

• Cryptozoon reefs are common in the Shakopee formation, and may be either thick lenticular masses which grade off laterally into beds of brecciated cryptozoon fragments or wide spread algal beds of relativesly uniform thickness. The associated shaly beds may show well-developed muc cracks with sand filling, and occasionally even ripple-marks appear among these local evidences of shallow water deposition. Over large areas the Shakopee appears as a massive gray to drab dolomite; more often, however, the thinner bedded Shakopee is really a dolomitic limestone whihc may be highly oolitic in the lower part of the formation and my contain large masses of oolitic chert.

Size class: macrofossils

Preservation: replaced with dolomite, replaced with silica

Primary reference: C. R. Stauffer. 1937. A diminutive fauna from the Shakopee Dolomite (Ordovician) at Cannon Falls, Minnesota. Journal of Paleontology 11(1):55-60 [P. Wagner/P. Wagner]more details

Purpose of describing collection: general faunal/floral analysis

PaleoDB collection 56647: authorized by Pete Wagner, entered by Pete Wagner on 21.11.2005

Creative Commons license: CC BY (attribution)

Taxonomic list

Cephalopoda
 Endocerida - Endoceratidae
"Orygoceras eburneolum n. sp." = Endoceras eburneolum, Cameroceras inopinatum n. sp.
"Orygoceras eburneolum n. sp." = Endoceras eburneolum Stauffer 1937
 Multiceratoidea - Bassleroceratidae
"Deltoceras tantillum n. sp." = Stylocyrtoceras tantillum
"Deltoceras tantillum n. sp." = Stylocyrtoceras tantillum Stauffer 1937
Tergomya
 Archinacellida - Archinacellidae
Archinacella simplex Billings 1865
Gastropoda
 Murchisoniina - Hormotomidae
Hormotoma cassina, "Hormotoma cannonensis n. sp." = Plethospira cannonensis
Hormotoma cassina Whitfield 1897 snail
"Hormotoma cannonensis n. sp." = Plethospira cannonensis Stauffer 1937 snail
 Murchisoniina - Lophospiridae
"Lophospira perelegans n. sp." = Lophospira perangulata, "Lophospira vetusta n. sp." = Lophospira perangulata
"Lophospira perelegans n. sp." = Lophospira perangulata Hall 1847 snail
"Lophospira vetusta n. sp." = Lophospira perangulata Hall 1847 snail
 Euomphalina - Euomphalidae
Euomphalopsis depressa n. sp. Stauffer 1937 snail
 Euomphalina - Raphistomatidae
Raphistoma shakopeense n. sp., "Raphistoma parvum n. sp." = Ceratopea parvum, Ceratopea pygmaea n. sp.
Raphistoma shakopeense n. sp. Stauffer 1937 snail
"Raphistoma parvum n. sp." = Ceratopea parvum Stauffer 1937 snail
Ceratopea pygmaea n. sp. Stauffer 1937 snail
operculum
 Euomphalina - Ophiletidae
"Eccyliomphalus transversocordatus n. sp." = Lecanospira transversocordatus
"Eccyliomphalus transversocordatus n. sp." = Lecanospira transversocordatus Stauffer 1937 snail