Where: Arizona (36.3° N, 111.9° W: paleocoordinates 0.0° N, 0.0° E)

• coordinate estimated from map

• outcrop-level geographic resolution

When: Walcott Member (Kwagunt Formation), Tonian (1000.0 - 850.0 Ma)

• About three meters below the lowermost lens of pisolitic chert and stratigraphically above the "flaky dolomite" bed of Ford and Breed (1972). Age of Walcott Member constrained by U-Pb dating of volcanic ash bed at the top (720.9 +/- 0.9 Ma, updated age from former 742 +/- 6 Ma age) and Re-Os dating yielding a 751.0 +/- 7.6 Ma age in the underlying Awatubi Member (both dates from Rooney et al., 2018).

• bed-level stratigraphic resolution

Environment/lithology: marine; lithified shale

Size class: microfossils

Collection methods: surface (float), chemical

Primary reference: B. Bloeser. 1985. Melanocyrillium, a new genus of structurally complex late Proterozoic microfossils from the Kwagunt Formation (Chuar Group), Grand Canyon, Arizona. Journal of Paleontology 59:741-765 [M. Clapham/M. Clapham]more details

Purpose of describing collection: taxonomic analysis

PaleoDB collection 227609: authorized by Matthew Clapham, entered by Matthew Clapham on 19.10.2022

Creative Commons license: CC BY (attribution)