51-52 m - Stratotype Ridge [Wheeler Shale] (Cambrian of the United States)

Where: Millard County, Utah (39.5° N, 113.0° W: paleocoordinates 4.6° S, 91.6° W)

• coordinate stated in text

• outcrop-level geographic resolution

When: Ptychagnostus gibbus trilobite zone, Wheeler Formation, Middle Cambrian (509.0 - 497.0 Ma)

• STRATIGRAPHIC RELATIONS: From lower Wheeler Formation, which overlies the Swasey Limestone. AGE: Marjuman; Ptychagnostus gibbus zone. STRATIGRAPHIC POSITION: From near base of section (51-52 m).

• bed-level stratigraphic resolution

Environment/lithology: coastal; lithified, fine-grained limestone

• SPECIFIC LITHOLOGY: Fine-grained limestone. LITHIFICATION: Lithified, on the basis of inspection of outcrop (Hendy, pers. com) and facies description.

Size class: macrofossils

Collection methods: surface (in situ),

• COLLECTOR: Babcock and others (not stated in text). REPOSITORY: Not stated in text.

Primary reference: L. E. Babcock, M. N. Rees, R. A. Robison, E. S. Langenburg, and S. Peng. 2004. Potential Global Standard Stratotype-section and Point (GSSP) for a Cambrian stage boundary defined by the first appearance of the trilobite Ptychagnostus atavus, Drum Mountains, Utah, USA. Geobios 37:149-158 [A. Hendy/A. Hendy]more details

Purpose of describing collection: taxonomic analysis

PaleoDB collection 86735: authorized by Austin Hendy, entered by Austin Hendy on 14.02.2009

Creative Commons license: CC BY (attribution)

Taxonomic list

• COVERAGE: Limited to characteristic trilobites. NOMENCLATURE: Not an authoritative publication, but with modern nomenclature and species-resolution identifications.
Artiopoda
 Agnostida - Peronopsidae
"Peronopsis interstricta" = Itagnostus interstrictus, Peronopsis fallax
"Peronopsis interstricta" = Itagnostus interstrictus White 1874
Peronopsis fallax Linnarsson 1869
 Agnostida - Ptychagnostidae
"Ptychagnostus gibbus" = Triplagnostus gibbus Linnarsson 1869
Trilobita
 Ptychopariida - Ptychopariidae
Ptychoparella sp. Poulson 1927 trilobite
 Ptychopariida - Alokistocaridae
Elrathia sp. Walcott 1924 trilobite