Decorah Shale (Stictopora mutabilis zone) Bryozoans, Upper Mississippi Valley (Ordovician of the United States)

Where: Minnesota, Iowa, Wisconsin, Illinois (42.5° N, 91.3° W: paleocoordinates 20.6° S, 63.7° W)

• coordinate estimated from map

• basin-level geographic resolution

When: Stictopora mutabilis zone, Decorah Shale Formation, Rocklandian (457.3 - 449.6 Ma)

• formation-level stratigraphic resolution

Environment/lithology: gray shale

• Environmental call by T. Hanson.
• 40-50 feet thick. "[G]reenish-gray or olive-green, fissile, commonly blocky, fossiliferous shale interbedded with scattered and locally discontinuous, thin limestone beds."

Size class: macrofossils

Primary reference: O. L. Karklins. 1987. Bryozoa from Rocklandian (Middle Ordovician) rocks of the Upper Mississippi Valley region. Middle and Late Ordovician lithostratigraphy and biostratigraphy of the Upper Mississippi Valley: Minnesota Geological Survey Report of Investigations 35 173-176 [S. Holland/T. Hanson/T. Hanson]more details

Purpose of describing collection: biostratigraphic analysis

PaleoDB collection 23312: authorized by Steven Holland, entered by Tori Hanson on 11.07.2002

Creative Commons license: CC BY (attribution)

Taxonomic list

Show authors, comments, and common names
Stenolaemata
 Trepostomida - Amplexoporidae
Amplexopora winchelli, Amplexopora minnesotensis
 Trepostomida - Monticuliporidae
Homotrypa subramosa, Prasopora simulatrix
Homotrypa subramosa Ulrich 1886
 Trepostomata - Dittoporidae
Hemiphragma irrasum
Hemiphragma irrasum Ulrich 1893
 Trepostomata - Heterotrypidae
Heterotrypa simplex, Heterotrypa echinata
Heterotrypa simplex
Heterotrypa praenuntia simplex
Heterotrypa echinata
Heterotrypa praenuntia echinata
 Cystoporata - Ceramoporidae
"Bythotrypa laxata" = Favositella
"Bythotrypa laxata" = Favositella
 Cryptostomata - Escharoporidae
Escharopora subrecta, Graptodictya simplex
 Cryptostomata - Rhinidictyidae
Stictopora lita, Stictopora exigua, Trigonodictya acuta
 Cryptostomata - Stictoporellidae
Pseudostictoporella angularis, Pseudostictoporella frondifera, Stictoporellina cribrosa