USGS Mesozoic loc. 20726 (Jurassic of the United States)

Where: Alaska (59.7° N, 153.4° W: paleocoordinates 31.5° N, 86.9° W)

• coordinate estimated from map

When: Tonnie Siltstone Member (Chinitna Formation), Callovian (166.1 - 163.5 Ma)

• Callovian, Chinitna Formation, 150 to 180 m (500-600 ft) above base of Tonnie Siltstone (loc. 240 of Detterman and Hartsock, 1966)

Environment/lithology: marine; massive, brown, gray, sandy siltstone and concretionary limestone

• Massive arenaceous dark-gray to brownish-gray siltstone constitutes most of the Tonnie Siltstone Member. The siltstone weathers brownish gray to red brown and contains numerous small yellowish brown- weathering limestone concretions that occur in parallel bands and at random throughout the section. Sandstone is present as thin interbeds in the siltstone, generally being fine grained and greenish gray. A more massive sandstone unit is present at the base of most sections.

Size classes: macrofossils, mesofossils

Collected by C.E. Kirschner in 1946; reposited in the USNM

Primary reference: T. P. Poulton. 1979. Jurassic Trigoniid Bivalves from Canada and Western United States of America. Geological Survey of Canada Bulletin 282 [G. Stanley/H. Shepherd/H. Shepherd]more details

Purpose of describing collection: taxonomic analysis

PaleoDB collection 139552: authorized by George Stanley, entered by Hannah Shepherd on 13.02.2013

Creative Commons license: CC BY (attribution)

Taxonomic list

 Trigoniida - Myophorelloidae
Myophorella orientalis Kobayashi and Tamura 1955 clam
Hypotype USNM 219872-219875