Hindia parva?-Sphenothallus-Apycnodiscus Communityof the Elgin: Maysvillian, Iowa

List of taxa
Where & when
Geology
Taphonomy & methods
Metadata & references
Taxonomic list
Demospongiae - Streptosclerophorida - Hindiidae
Trilobita
Trilobita indet. Walch 1771
Ostracoda
Rhynchonellata - Orthida - Platyorthidae
Lingulata - Acrotretida - Acrotretidae
Conotreta sp. Walcott 1889
Lingulata - Acrotretida - Scaphelasmatidae
Scaphelasma sp. Cooper 1956
Lingulata - Lingulida - Lingulasmatidae
Lingulata - Lingulida - Obolidae
unclassified
Bryozoa indet. Ehrenberg 1831
Polychaeta
Polyplacophora
Gastropoda
Gastropoda - Bellerophontida - Bellerophontidae
Gastropoda - Bellerophontida - Bucanellidae
Gastropoda - Euomphalina - Platyceratidae
Gastropoda - Murchisoniina - Hormotomidae
Gastropoda - Murchisoniina - Lophospiridae
Gastropoda - Murchisoniina - Eotomariidae
Bivalvia - Nuculanida - Malletiidae
Bivalvia - Nuculanida - Cucullellidae
Cephalopoda - Orthocerida - Proteoceratidae
Isorthoceras sociale (Hall in Miller 1877)
Conodonta
Conodonta indet. Pander 1856
unclassified
Scaphopoda - Dentaliida - Dentaliidae
unclassified
Pterobranchia - Graptoloidea - Diplograptidae
Orthograptus truncatus peosta
Pterobranchia - Graptoloidea - Climacograptidae
Climacograptus typicalis putillus
Asteroidea
undetermined starfish plates
Cyclocystoidea - Cyclocystoididae
Crinoidea
Crinoidea indet. Miller 1821
undetermined crinoid plates
see common names

Geography
Country:United States State/province:Iowa County:Allamakee County
Coordinates: 43.3° North, 91.4° West (view map)
Paleocoordinates:15.2° South, 116.4° West (Wright 2013)
Basis of coordinate:based on political unit
Geographic resolution:outcrop
Time
Period: Ordovician Epoch: Late Ordovician
Stage: Katian 10 m.y. bin: Ordovician 5
*Period:Late/Upper Ordovician *Epoch:Early/Lower Ashgill
*Local age/stage:Maysvillian
Key time interval: Maysvillian
Age range of interval: 450.2 - 449.6 m.y. ago
* legacy (obsolete) database fields
Stratigraphy
Formation:Maquoketa Member:Elgin
Stratigraphic resolution:group of beds
Stratigraphy comments: Basal 15 cm phosphorite in Elgin Member, Maquoketa Formation, at Dubuque Formation contact.
Lithology and environment
Primary lithology:dolomitic,pyritic lithified phosphorite
Lithology description: The lithology is a poorly consolidated to pyrite-cemented dolomitic phosphorite ranging in thickness from 0.1 to 0.3 m. Most common are small (<2 mm) subsphaeroidal concentrically laminated hydroxylapatite clasts, but less well rounded phosphate clasts up to 15 cm in length and phosphatized fossils are also abundant. Locally quartz geodes ranging in size from 1 cm to more than 25 cm in length are common, e.g., at the type locality. The geodes contain minor sulfide mineralization (wire marcasite) and common calcite, ferroan dolomite, fluorite, and selenite crystals in the often largely hollow interiors... This community appears to have been subject to some current activity, but not frequently enough to remove selectively particular size clasts. The deposit is very poorly sorted, at least basally, with clay to gravel-sized clasts intermixed, some or all of which may be phosphatized.
Environment:deep subtidal ramp Tectonic setting:cratonic basin
Geology comments: The strong tendency for some groups to be preserved articulated while echinoderms are not suggests a rather low sedimentation accumulation rate, but this is not a true starved basin situation. The pitted and mineralized Maquoketa-Dubuque contact resembles many other corrosion surfaces in the Upper Mississippi Valley Galena Group (Witzke, 1985b), and likely formed in a submarine, not subaerial environment. If the suggestion of Brown (1974) that upwelling of oxygen-poor, phosphate-rich waters into a typical carbonate shelf edge produced the diminutive Maquoketa faunas is correct, then this community, with a significant but small echinoderm component, marks the transition from the highly affected Palaeoneilo fecunda-Nuculites neglectus Community (with almost no echinoderms) to the more normal marine Thaerodonta recedens-Iowacystis sagittaria Community. Benthic assemblages have not been defined for many Ordovician communities as yet, but a position analogous to BA 3-4 is probable (see also Witzke & Glenister, 1987, for further discussion).
Taphonomy
Modes of preservation:body,replaced with phosphate
Collection methods and comments
Reason for describing collection:paleoecologic analysis
Metadata
Database number:13261
Authorizer:M. Foote Enterer:K. Koverman
Modifier:M. Foote Research group:marine invertebrate
Created:2002-02-04 09:32:32 Last modified:2025-02-22 15:12:02
Access level:the public Released:2002-02-04 09:32:32
Creative Commons license:CC0
Reference information

Primary reference:
4379. 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]

Secondary references:

9042 P. J. Wagner. 2023. Paleozoic Gastropod, Rostroconch, Helcionelloid and Tergomyan Database (2006 - 2023). [P. Wagner/P. Wagner/P. Wagner]