Muddy Mountains Overton locality - Placunopsis bioherm (Triassic of the United States)

Also known as Reef 3557

Where: Nevada (36.6° N, 114.5° W: paleocoordinates 7.9° N, 40.3° W)

• coordinate estimated from map

• small collection-level geographic resolution

When: Virgin Limestone Member (Moenkopi Formation), Spathian (251.3 - 247.2 Ma)

• bed-level stratigraphic resolution

Environment/lithology: reef, buildup or bioherm; lithified bindstone

• Placunopsis bioherms. Nine individual bivalve mounds occur in a single bed across 100 m of lateral exposure.The internal structure of all the bioherms consists of small, irregularly stacked Placunopsis valves (1–10 mm in length, 1 mm thick) that appear in the field as stacked millimeter-size elongate clasts. The Placunopsis bioherms broadly resemble stromatolites (Bachmann, 1979) due

•to their hemispheroidal, columnar, and laminated macrostructures. The

•small size and irregular shape of the shells also makes it difficult to

•recognize them as bivalves in the field.

Size class: mesofossils

Preservation: replaced with silica

Collection methods: peel or thin section,

Primary reference: S. B. Pruss, J. L. Payne, and D. J. Bottjer. 2007. Placunopsis bioherms; the first metazoan buildups following the end-Permian mass extinction. Palaios 22(1):17-23 [W. Kiessling/W. Kiessling]more details

Purpose of describing collection: taphonomic analysis

PaleoDB collection 72425: authorized by Wolfgang Kiessling, entered by Wolfgang Kiessling on 04.06.2007

Creative Commons license: CC BY (attribution)

Taxonomic list

Show authors, comments, and common names
Bivalvia
 Pectinida - Anomiidae
Placunopsis sp.
Placunopsis sp. Morris and Lycett 1853 scallop
conservative estimate based on figures and description