Where: Jackson County, Iowa (42.2° N, 90.5° W: paleocoordinates 21.0° S, 55.5° W)
• coordinate based on political unit
• basin-level geographic resolution
When: Cycle V zone, Hopkinton Dolomite Formation, Llandovery (443.7 - 428.2 Ma)
• "Early Sil. Llandovery and basal Wenlock. C5"
Environment/lithology: deep subtidal shelf; cherty/siliceous dolomite
Primary reference: J. J. Sepkoski Jr. 1998. Rates of speciation in the fossil record. Philosophical Transaction of the Royal Society Biological Sciences 353(1366):315-326 [J. Sepkoski/M. Sommers/A. Clement] more details
PaleoDB collection 457: authorized by Arnold Miller, entered by Mike Sommers on 10.12.1998