02085nas a2200217   4500008004100000245013600041210006900177300001400246490000700260520131700267653001701584653002201601653001801623653004201641653003101683100001901714700002001733700001801753700001601771856008001787       2014                        eng d00aTrilobite Biostratigraphy of the Stairsian Stage (upper Tremadocian) of the Ibexian Series, Lower Ordovician, Western United States0 aTrilobite Biostratigraphy of the Stairsian Stage upper Tremadoci  a167–2140 v453 a<p>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.</p>
10apaleontology10aSpecies diversity10aStratigraphic10aTrilobites--Collectors and collecting10aTrilobites--Type specimens1 aAdrain, J., M.1 aWestrop, S., R.1 aKarin, T., S.1 aLanding, E.  uhttp://search.informit.com.au/documentSummary;dn=343657705520848;res=IELHSS