Dimerocrinites (D.) hopkintonensis Assoc., Welton Mbr., Scotch Grove Fm., E Iowa (Silurian to of the United States)

Where: Iowa (41.8° N, 91.1° W: paleocoordinates 21.5° S, 55.8° W)

• coordinate based on political unit

• local area-level geographic resolution

When: Welton Member (Scotch Grove Formation), Telychian to Telychian (438.5 - 430.5 Ma)

• "Late Llandovery (C5-C6) to Early Wenlockian...Lower and Middle Welton Member..."

• member-level stratigraphic resolution

Environment/lithology: deep subtidal ramp; dolomitic, shelly/skeletal wackestone and dolomitic, shelly/skeletal packstone

• "Pelmatozoan root systems are noted, and both coarse skeletal debris and whole fossils are common. Echinoderms generally found as intact calices...many of the brachiopods articulated...little sign of winnowing, size sorting, or cross-bedding...This comm. likely occupies a relatively broad range, from outer BA 3 to inner BA 4...not an echinoderm thicket..."

•

•SEP environmental call based on given description and same vol. page 807.

• "The community occurs in a horizontally bedded, porous, very fossiliferous, skeletal-moldic dolowckestone-dolopackstone."

Collection methods: This is closely related to PBDB coll. 24963, which includes some echinoderms, but the two collections are not identical.

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 26715: authorized by Michael Foote, entered by Michael Foote on 25.10.2002

Creative Commons license: CC BY (attribution)

Taxonomic list

• Echinoderms only.
Show authors, comments, and common names
 Rhombifera - Callocystitidae
Callocystitidae indet.
Callocystitidae indet. Bernard 1895
apiocystitinid
Crinoidea
 Monobathrida - Dolatocrinidae
Allocrinus cf. subglobosus
 Monobathrida - Eucalyptocrinitidae
Eucalyptocrinites depressus, Eucalyptocrinites inornatus, Eucalyptocrinites cf. ornatus
 Monobathrida - Marsupiocrinidae
Marsupiocrinus (Amarsupiocrinus) primaevus
 Diplobathrida - Gazacrinidae
Pregazacrinus hemisphericus
 Diplobathrida - Dimerocrinitidae
Dimerocrinites (Dimerocrinites) hopkintonensis
 Diplobathrida - Lampterocrinidae
Siphonocrinus nobilis
Trilobita
  -
Trilobita indet.
Trilobita indet. Walch 1771 trilobite
Cephalopoda
 Nautiloidea -
Nautiloidea indet.
Nautiloidea indet. Agassiz 1847 nautiloid
Gastropoda
  -
Gastropoda indet.
Gastropoda indet. Cuvier 1795 snail
Bivalvia
  -
"Pelecypoda indet." = Bivalvia
"Pelecypoda indet." = Bivalvia Linnaeus 1758 clam
Anthozoa
 Tabulata -
Tabulata indet.
Tabulata indet. tabulate coral
 Rugosa -
Rugosa indet.
Rugosa indet. horn coral