East of Bear Lake (Jurassic of the United States)

Where: Bear Lake County, Idaho (42.1° N, 111.2° W: paleocoordinates 34.8° N, 52.2° W)

• coordinate stated in text

• outcrop-level geographic resolution

When: Boundary Ridge Member (Twin Creek Formation), Bathonian (168.3 - 166.1 Ma)

• "probably Bathonian age beds... lower part of the Twin Creek Limestone, some 175.3-182.9 m above the Lower Jurassic Nugget Formation in... the lower part of the Boundary Ridge Member"

• group of beds-level stratigraphic resolution

Environment/lithology: sand shoal; lithified, medium-grained, shelly/skeletal, yellow, argillaceous grainstone

• "shallow water, moderate energy marine environment" with "small oyster banks" that was "probably less than 30 m" in depth and is "interpreted to have formed on offshore bars"
• "buff-yellow weathering, slightly argillaceous, medium grained biosparites which locally have an intact framework of oyster, crinoid, and brachiopod shell debris. The fossiliferous units comprise 15-25-cm thick, resistant, lensoid beds (traced over 18 m laterally) which contain a very abundant silicified shelly fauna"

Size class: macrofossils

Preservation: original silica, shellbed

Collected by D. G. Perry, B. D. E. Chatterton in 1975; reposited in the GSC

Collection methods: bulk, quarrying, acetic, hydrochloric,

• "Four silicified blocks, representing approximately 27 kg of rock were dissolved in hyrochloric and acetic acids in order to recover the silicified faunas"

Primary reference: D. G. Perry. 1979. A Jurassic brachiopod-oyster association, Twin Creek Limestone, southeastern Idaho. Journal of Paleontology 53(4):997-1004 [J. Alroy/J. Alroy/J. Alroy]more details

Purpose of describing collection: taxonomic analysis

PaleoDB collection 90912: authorized by John Alroy, entered by John Alroy on 25.08.2009

Creative Commons license: CC BY (attribution)

Taxonomic list

Rhynchonellata
 Terebratulida - Terebratulidae
Terebratulidae indet. Gray 1840
juveniles
 Rhynchonellida - Erymnariidae
Cryptorhynchia bearensis n. sp. Perry 1979
Bivalvia
 Ostreida - Gryphaeidae
? Liostrea strigilecula White 1877 oyster
Cephalopoda
 Belemnoidea -
Belemnitida indet. Zittel 1895 belemnite
fragmental guards
Crinoidea
  -
Pentacrinus sp. Miller 1821 Sea lily
mostly ossicles
Hydrozoa
 Milleporina -