TH Pit (Cambrian of the United States)

Where: Esmeralda County, Nevada (37.7° N, 117.3° W: paleocoordinates 1.3° S, 95.0° W)

• coordinate stated in text

When: Bonnia-Olenellus trilobite zone, Middle Member (Poleta Formation), Dyeran (515.3 - 511.2 Ma)

• "The base of the Dyeran Stage is drawn at the abrupt faunal change from “Nevadella” Zone trilobites to those of the Bonnia- Olenellus Zone (Fritz, 1972). This distinct transition occurs 97 m above the base of the middle member of the Poleta at the stratotype section. In turn, the TH Pit is 64 m above this stage boundary."

Environment/lithology: open shallow subtidal; calcareous siltstone and lenticular, fine-grained sandstone

• The middle member is mostly siliciclastics, 198 m thick, beginning with deep subtidal siltstones, shallowing upward through an interval of sandstones and siltstones with inter- bedded carbonate beds.
• "At the TH Pit, the fossiliferous interval ranges from 26 to 48 cm in thickness averaging about 30 cm. The calcareous siltstone is commonly laminated but portions up to two cm thick have obscure, swirled bedding (Fig. 2b). This bed has

•been traced laterally for at least 250 m where it sometimes contains numerous lenses and clasts of carbonate. The tri- lobite content is variable but they are never as common as at the TH Pit. Above and below this bed, there are numer- ous fine sandstone beds about a meter thick (Fig. 1c). These beds are lenticular along strike, with laminated bedding sometimes swirled into ball-and-pillow structures (Fig. 2d).

Size class: macrofossils

Collected by J. S. Hollingsworth; reposited in the USNM

Collection methods: bulk, quarrying, mechanical,

• "Nearly a tonne of material has been removed and split. The hand-dug pits are located at 37°43.48'N and 117°19.00'W."

•"Illustrated materials are reposited in the collections of the Department of Paleobiology, National Museum of National History (USNM), Smithsonian Institution, Washington, DC. and the Institute for Cambrian Studies reference and replica collection (ICS). The remainder of the TH Pit collection is housed in my personal biostratigraphic collections."

Primary reference: J. S. Hollingsworth. 2005. A trilobite fauna in a storm bed in the Poleta Formation (Dyeran, Lower Cambrian), western Nevada, U.S.A. Geosciences Journal 9(2):129-143 [J. Marcot/J. Marcot]more details

Purpose of describing collection: general faunal/floral analysis

PaleoDB collection 204959: authorized by Jonathan Marcot, entered by Jonathan Marcot on 01.10.2019

Creative Commons license: CC BY (attribution)

Taxonomic list

Show authors, comments, and common names
Trilobita
 Corynexochida - Edelsteinaspididae
Polliaxis hanseni n. sp.
Polliaxis hanseni n. sp. Hollingsworth 2005 trilobite
 Redlichiida - Olenellidae
Teresellus goldfieldensis n. gen. n. sp.
Teresellus goldfieldensis n. gen. n. sp. Hollingsworth 2005 trilobite
 Redlichiida - Wanneriidae
Elliptocephala praenuntius
Elliptocephala praenuntius Cowie 1968 trilobite
 Ptychopariida - Solenopleuridae
? Keeleaspis terhaari n. sp.
? Keeleaspis terhaari n. sp. Hollingsworth 2005 trilobite