| Winneshiek Shale | |
|---|---|
| Stratigraphic range: | |
 Winneshiek Shale strata exposed via a temporary dam (a-d) | |
| Type | Formation |
| Underlies | St. Peter Sandstone |
| Overlies | unnamed breccia unit |
| Thickness | 38 m[1] |
| Lithology | |
| Primary | shale |
| Location | |
| Region | Upper Midwest |
| Country | United States |
| Extent | Iowa |
| Type section | |
| Named for | Winneshiek County, Iowa |
| Named by | Liu et al., 2006 (as "Winneshiek Lagerstätte")[1] |
 Location of the Decorah crater in Iowa, the only area where the Winneshiek Shale is found | |
The Winneshiek Shale (originally the Winneshiek Lagerstätte) is a Middle Ordovician (Darriwilian-age) geological formation in Iowa. The formation is restricted to the Decorah crater, an impact crater near Decorah, Iowa. Despite only being discovered in 2005, the Winneshiek Shale is already renowned for the exceptional preservation of its fossils. The shale preserves a unique ecosystem, the Winneshiek biota, which is among the most remarkable Ordovician lagerstätten in the United States.[2] Fossils include the oldest known eurypterid, Pentecopterus,[3] as well as giant conodonts such as Iowagnathus and Archeognathus.[4]
- ^ a b Cite error: The named reference
Liu2006was invoked but never defined (see the help page). - ^ Briggs, Derek E.G.; Liu, Huaibao P.; McKay, Robert M.; Witzke, Brian J. (24 September 2018). "The Winneshiek biota: exceptionally well-preserved fossils in a Middle Ordovician impact crater". Journal of the Geological Society. 175 (6): 865–874. Bibcode:2018JGSoc.175..865B. doi:10.1144/jgs2018-101. S2CID 85450625.
- ^ Lamsdell, James C.; Briggs, Derek E. G.; Liu, Huaibao; Witzke, Brian J.; McKay, Robert M. (September 1, 2015). "The oldest described eurypterid: a giant Middle Ordovician (Darriwilian) megalograptid from the Winneshiek Lagerstätte of Iowa". BMC Evolutionary Biology. 15: 169. doi:10.1186/s12862-015-0443-9. PMC 4556007. PMID 26324341.
- ^ Liu, Huaibao P.; Bergström, Stig M.; Witzke, Brian J.; Briggs, Derek E. G.; McKay, Robert M.; Ferretti, Annalisa (2017-05-01). "Exceptionally preserved conodont apparatuses with giant elements from the Middle Ordovician Winneshiek Konservat-Lagerstätte, Iowa, USA". Journal of Paleontology. 91 (3): 493–511. Bibcode:2017JPal...91..493L. doi:10.1017/jpa.2016.155. ISSN 0022-3360.