Orchard Creek Exposure, 1.6 km north of Thebes (Ordovician of the United States)
Where: Alexander County, Illinois (37.2° N, 89.5° W: paleocoordinates 24.5° S, 61.5° W)
• coordinate based on political unit
• outcrop-level geographic resolution
When: Girardeau Limestone Formation, Hirnantian (445.2 - 443.4 Ma)
Environment/lithology: limestone
• The Girardeau is composed of two alternating lithologies which are cyclically interbedded in units ranging from two to four inches (5.1 to 10.2 cm) thick. The predominant rock in a single cycle (about 75 to 80%) is a dark green massive and unlaminated lithographic limestone. Most of this material represents clay-sized and silt-sized calcite, although clay minerals are present.
Size class: macrofossils
Primary reference: J. C. Brower. 1973. Crinoids from the Girardeau Limestone (Ordovician). Palaeontographia Americana 7(46):263-499 [G. Webster/G. Webster]more details
Purpose of describing collection: taxonomic analysis
PaleoDB collection 201761: authorized by Pete Wagner, entered by Pete Wagner on 26.05.2019
Creative Commons license: CC BY (attribution)
Taxonomic list
Show authors, comments, and common names
Crinoidea | |
Macrostylocrinus pristinus Sea lily
Eopatelliocrinus scyphogracilis Sea lily
Eopatelliocrinus latibrachiatus Sea lily | |
? Culicocrinus girardeauensis Sea lily | |
Alisocrinus tetrarmatus Sea lily |