Otta (Ordovician of Norway)

Where: Norway (61.8° N, 9.5° E: paleocoordinates 32.8° S, 11.2° W)

When: Otta Conglomerate Formation, Early/Lower Llanvirn (466.0 - 463.5 Ma)

• The generic composition of the Otta brachiopods suggests a late Arenig-early Llanvirn age for the conglomerate. Direct specific comparisons are difficult due to firstly, inadequate Otta material, e.g. Valcourea sp., and secondly, a paucity of well documented congeners of many species, e.g. Trondorthis, Neumania and Calyptolepta; thus the desirable correlations based upon specific similarity are not possible. However, on the evidence of the Trondorthis and Valcourea, the assemblage is more probably early Llanvirn than late Arenig.

• formation-level stratigraphic resolution

Environment/lithology: sandstone

• Assuming the serpentinites formed positive areas above the sea-floor, they may have afforded ideal sites for the colonisation of shelly faunas. Periodic down-slope movement of erosion products together with the associated benthos and nekton is envisaged to account for the unusual mode of occurrence of the Otta fossils.
• The Otta fossils occur as clasts in a matrix of detrital serpentine.

Size class: macrofossils

Preservation: cast

Primary reference: D. L. Bruton and D. A. T. Harper. 1981. Brachiopods and trilobites of the early Ordovician serpentine Otta Conglomerate, south central Norway. Norsk Geologisk Tidsskrift 61:153-181 [P. Wagner/P. Wagner]more details

Purpose of describing collection: taxonomic analysis

PaleoDB collection 185943: authorized by Pete Wagner, entered by Pete Wagner on 27.05.2017

Creative Commons license: CC BY (attribution)

Taxonomic list

Brachiopoda indet. Cuvier 1805
Orthambonites sp. or Trondorthis subcircularis
 Billingsellida - Clitambonitidae
"Neumania aff. atlanticus" = Palaeoneumania atlanticus
"Neumania aff. atlanticus" = Palaeoneumania atlanticus Neuman 1976
 Strophomenida - Grorudiidae
 Strophomenida - Sowerbyellidae
? Ptychoglyptus sp. Willard 1928
 Strophomenida - Taffiidae
Rutrumella implexa n. gen. n. sp.
Rutrumella implexa n. gen. n. sp.
 Pentamerida - Tetralobulidae
Palaeostrophia sp. Ulridch and Cooper 1936
 Pentamerida - Camerellidae
Camerella sp. Billings 1859
 Orthida - Paurorthidae
? Paurorthis sp. Schuchert and Cooper 1931
 Orthida - Orthidae
 Orthida -
Ottadalenites incertus n. gen. n. sp.
Ottadalenites incertus n. gen. n. sp.
 Orthida - Plaesiomyidae
Valcourea sp. Raymond 1911