Trilobite biostratigraphy of the Stairsian Stage (upper Tremadocian) of the Ibexian Series, Lower Ordovician, western United States

Jonathan M Adrain; Stephen R Westrop; Talia S Karim; Ed Landing

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Journal article

Trilobite biostratigraphy of the Stairsian Stage (upper Tremadocian) of the Ibexian Series, Lower Ordovician, western United States

Jonathan M Adrain, Stephen R Westrop, Talia S Karim and Ed Landing

Memoir ... of the Association of Australasian Palaeontologists, Vol.45, pp.167-214

2014

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Abstract

New field collections from sections in western Utah and southeastern Idaho permit the development of a high resolution trilobite biostratigraphy for the northern Laurentian Lower Ordovician (upper Tremadocian) Stairsian Stage similar to that proposed previously for the overlying Tulean and Blackhillsian stages. Four zones recognised previously are replaced with 11 formally proposed zones, most of which are new in concept. The new zonal scheme in ascending order includes the 'Paraplethopeltis genacurva' Zone (replaces 'Paraplethopeltis Zone'/'Zone C'), 'Paraplethopeltis helli' Zone (new), 'Hystricurus zanderi' Zone (new), 'Rossaspis leboni' Zone (new), Unnamed Zone 1 (new), 'Bearriverops loganensis' Zone (new; contains much of the diversity previously assigned to 'Tesselacauda Zone'/'Zone E'), 'Bearriverops deltaensis' Zone (new), 'Bearriverops alsacharovi' Zone (new), 'Pseudoclelandia weymouthae' Zone (new), 'Pseudoclelandia cornupsittaca' Zone (new) and 'Pseudohystricurus obesus' Zone (new). The latter two zones were previously lumped as the 'Rossaspis superciliosa Zone'/'Zone F'. Four of the name bearers of the new zones, 'Paraplethopeltis helli' sp. nov., 'Hystricurus zanderi' sp. nov., 'Rossaspis leboni' sp. nov. and 'Pseudoclelandia weymouthae' sp. nov., are formally described.

Arthropoda

assemblages

biostratigraphy

biozones

Hystricurus

Hystricurus zanderi

Ibexian

Idaho

Invertebrata

Invertebrate paleontology

Laurentia

Lower Ordovician

morphology

new names

new taxa

Ordovician

Paleozoic

Paraplethopeltis

Paraplethopeltis helli

Pseudoclelandia

Pseudoclelandia weymouthae

Rossaspis

Rossaspis leboni

southeastern Idaho

species diversity

Stairsian

taxonomy

Tremadocian

Trilobita

Trilobitomorpha

United States

upper Tremadocian

Utah

western Utah

Details

Title: Subtitle: Trilobite biostratigraphy of the Stairsian Stage (upper Tremadocian) of the Ibexian Series, Lower Ordovician, western United States
Creators: Jonathan M Adrain - University of Iowa
Stephen R Westrop
Talia S Karim
Ed Landing
Contributors: John R Laurie (Editor) - Geoscience Australia
John R Paterson (Editor)
Glenn A Brock (Editor)
Resource Type: Journal article
Publication Details: Memoir ... of the Association of Australasian Palaeontologists, Vol.45, pp.167-214
Publisher: Association of Australasian Palaeontologists
ISSN: 0810-8889
Alternative title: Cambro-Ordovician studies; V
Language: English
Date published: 2014
Academic Unit: Earth and Environmental Sciences
Record Identifier: 9984229179702771

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