Silver Peak Range, 10 km South Coaldale Junction (Cambrian to of the United States)

Where: Esmarelda County, Nevada (38.0° N, 117.0° W: paleocoordinates 1.2° S, 91.0° W)

• coordinate based on nearby landmark

• hand sample-level geographic resolution

When: Emigrant Formation, St Davids to St Davids (513.0 - 485.4 Ma)

• Identifiable

•fossils from the limestone and chert member are Upper Cambrian

•(Albers and Stewart, 1972), but the only other fossils directly

•associated with Quasimodaspis are poorly preserved inarticulate

•brachiopods (Fig. 2.7), which have not been identified. The arthropod

•fossils were originally identified as ‘‘questionable Middle

•Cambrian’’ on the basis of their resemblance to Burgess Shale

•taxa (Albers and Stewart, 1972). However, as will be shown in

•the systematic description, Quasimodaspis is not a Burgess Shaletype

•arthropod, but an aglaspidid. Most aglaspidids are Upper

•Cambrian in age, although a few are Middle Cambrian. The available

•evidence seems to favor an Upper Cambrian age for Quasimodaspis,

•but there is not enough evidence at this time to date

•Quasimodaspis precisely.

• group of beds-level stratigraphic resolution

Environment/lithology: dolomitic, red, yellow dolomite

• The arthropod specimens from Emigrant Pass, described in this

•paper as Quasimodaspis brentsae gen. et sp. nov., come from a

•thickly bedded, clastic-rich dolomitic unit, ranging from dark red

•to pink, orange and yellow in color. The unit contains both siliceous

•and carbonate grains up to 2 mm in diameter, and is overlain

•by a thick sequence of partially metamorphosed, unfossiliferous

•‘‘pencil’’ shales.

Size class: macrofossils

Reposited in the USNM

Primary reference: B. Waggoner. 2003. Non-trilobite arthropods from the Silver Peak Range, Nevada. Journal of Paleontology 77:706-720 [A. McGowan/A. McGowan/J. Marcot]more details

Purpose of describing collection: taxonomic analysis

PaleoDB collection 55500: authorized by Alistair McGowan, entered by Alistair McGowan on 28.10.2005

Creative Commons license: CC BY (attribution)

Taxonomic list

Artiopoda
 Aglaspidida - Tremaglaspididae
Quasimodaspis brentsae Waggoner 2003
Five nearly complete, four fragmentary