Diamphidiocystis drepanon-Savagella Comm., Orchard Creek Shale, Scales Fm. (Ordovician of the United States)

Where: Illinois (37.2° N, 89.5° W: paleocoordinates 24.7° S, 62.9° W)

• coordinate based on political unit

• local area-level geographic resolution

When: Orchard Creek Shale Member (Scales Formation), Richmondian (449.6 - 445.5 Ma)

• "Richmondian of current Illinois usage" 1-3 m above contact with Thebes Sst.

• member-level stratigraphic resolution

Environment/lithology: deep subtidal; burrowed, bioturbated, silty, calcareous shale and burrowed, bioturbated, argillaceous limestone

• "Guesburg (1988) interprets theunit as a low-energy environment with a rapid rate of depostion and occasional moderate wave or current activity. He facored a shallow subtidal position, but the rate of depostion and comparison with better known communities from rocks of similar age and environment (e.g. other Maquoketa Group communities) suggest a more offshore position, perhaps corresponding with an outer BA 3 to well into 4, somewhat restricted Silurian assemblage." This community is grouped by authors with others having a deeper shelf environment relative to the shoal margin communities.

•SEP environmental call based on given information and regional context

• "At te single known locality scattered shelly fossils are sparsely distributed in calcareous silty shales and hard argillaceous limestones...grazing trails, burrows, and burrow mottling...most fossils except trilobites are whole..."

Collection methods: Some overlap with PBDB collections 23235-6, 23521-2, 23682, 23684, 23783-4, and 23810-11, but not a duplicate entry.

Primary reference: T. J. Frest, C. E. Brett, and B. J. Witzke. 1999. Caradocian-Gedinnian echinoderm associations of Central and Eastern North America. Paleocommunities--a case study from the Silurian and Lower Devonian 638-783 [M. Foote/K. Koverman/P. Wagner]more details

Purpose of describing collection: paleoecologic analysis

PaleoDB collection 26684: authorized by Michael Foote, entered by Michael Foote on 24.10.2002

Creative Commons license: CC BY (attribution)

Taxonomic list

Show authors, comments, and common names
Trilobita
 Asaphida - Asaphidae
Isotelus sp.
Isotelus sp. Dekay 1824 trilobite
 Corynexochida - Illaenidae
Bumastus sp.
Bumastus sp. Murchison 1839 trilobite
Gastropoda
 Bellerophontida - Bucaniidae
Phragmolites sp.
Phragmolites sp. Conrad 1838 snail
Bivalvia
  -
"Pelecypoda indet." = Bivalvia
"Pelecypoda indet." = Bivalvia Linnaeus 1758 clam
 Lophophorata -
Tentaculitida indet.
Tentaculitida indet. Ljaschenko 1955
Rhynchonellata
 Orthida - Dalmanellidae
Paucicrura sp.
Paucicrura sp. Cooper 1956
Strophomenata
 Strophomenida - Rafinesquinidae
Rafinesquina sp.
Rafinesquina sp. Hall and Clarke 1892
Bryozoa
  -
Bryozoa indet.
Bryozoa indet. Ehrenberg 1831
Stylophora
 Mitrata - Anomalocystitidae
Enoploura sp.
Enoploura sp. Wetherby 1879
 Mitrata -
Diamphidiocystis drepanon
Edrioasteroidea
 Isorophida - Lebetodiscidae
Euhydrodiskos sp.
Euhydrodiskos sp. Guensburg 1988
 Isorophida - Agelacrinitidae
Savagella sp., Hystrichopsydrax sp.
Hystrichopsydrax sp. Guensburg 1988
  - Pyrgocystidae
? Pyrgocystis sp.
? Pyrgocystis sp. Bather 1915
 Isorophina - Isorophidae
? Isorophus sp.
? Isorophus sp. Foerste 1916
Crinoidea
  -
Crinoidea indet.
Crinoidea indet. Miller 1821 Sea lily
 Rhombifera - Callocystitidae
Lepadocystis sp.
Lepadocystis sp. Carpenter 1891
Anthozoa
 Stauriida - Streptelasmatidae
Salvadorea randi
Salvadorea randi horn coral