P. gibbus Zone, Wheeler Fm., Milllard County, UT - Robison 1999 (Cambrian of the United States)

Where: Millard County, Utah (39.5° N, 112.9° W: paleocoordinates 4.8° S, 92.1° W)

• local area-level geographic resolution

When: Ehmaniella zone, Wheeler Formation, Delamaran (511.2 - 506.5 Ma)

• 300 meter thick formation at this locality and horizontal exposure of 8km, but fossils described from basal 63m. Environment is interpretted to be a marine shelf basin at depths below storm wave-base.

• group of beds-level stratigraphic resolution

Environment/lithology: basinal (); lithified, black, calcareous shale

• monofacial succession of thin, dark laminated calcareous shale.

Collection methods: May represent a shell accumulation due to a sediment lag which was reworked and then lithified

Primary reference: R. A. Robison. 1999. Base of Ptychagnostus atabus Zone, candidate stratotype for base of unnamed international series. Laurentia 99: V field conference of the Cambrian Stage Subdivision Working Group, International Subcomission on Cambrian Stratigraphy 15-17 [M. Patzkowsky/P. Borkow]more details

Purpose of describing collection: biostratigraphic analysis

PaleoDB collection 10566: authorized by Mark Patzkowsky, entered by Phil Borkow on 23.05.2001

Creative Commons license: CC BY (attribution)

Taxonomic list

• Only trilobites are described to genus/species level
Artiopoda
 Agnostida - Peronopsidae
"Peronopsis segmenta" = Pentagnostus (Meragnostus) segmenta Robison 1964
"Peronopsis interstricta" = Itagnostus interstrictus White 1874
 Agnostida - Ptychagnostidae
"Ptychagnostus gibbus" = Triplagnostus gibbus Linnarsson 1869
 Agnostida - Diplagnostidae
"Peronopsis acadica" = Acadagnostus acadica
"Peronopsis acadica" = Acadagnostus acadica Hartt 1868