Where: Idaho (42.2° N, 111.5° W: paleocoordinates 11.7° N, 35.4° W)

• coordinate estimated from map

• local area-level geographic resolution

When: Thaynes Group, Spathian (251.3 - 247.2 Ma)

• The exposures dip gently northward and their combined thickness reaches ~20 m. They are located below the Spathian Middle Limestone unit and overlie the Smithian Lower Limestone unit. However, the contact with the Lower Limestone unit is not visible in this area. The occurrence of the ammonoid species Tirolites harti indicates an early Spathian age for the Middle Limestone unit. This unit is coeval or slightly older than the Tirolites/Columbites beds of South China, which yield a radiometric age of ~250.55 ± 0.4 Ma. Abundant Tirolites specimens are also reported here for the first time from the upper part of the underlying Lower Shale unit where the Paris Biota occurs; unfortunately, their compressed preservation prevents a firm species assignment. However, the genus determination is easy and robust enough to confirm an earliest Spathian age for this biota as this genus is found worldwide in this time interval only. Tirolites specimens are found throughout the four studied exposures of the upper part of the Lower Shale unit, confirming their earliest Spathian age.

• group of beds-level stratigraphic resolution

Environment/lithology: transition zone or lower shoreface; lithified, silty mudstone and lithified marl

Size classes: macrofossils, mesofossils

Preservation: mold/impression

Collection methods: Repository: Université de Bourgogne, Géologie Dijon, France

Primary reference: A. Brayard, L. J. Krumenacker, J. P. Botting, J. F. Jenks, K. G. Bylund, E. Fara, E. Vennin, N. Olivier, N. Goudemand, T. Saucède, S. Charbonnier, C. Romano, L. Doguzhaeva, B. Thuy, M. Hautmann, D. A. Stephen, C. Thomazo and G. Escarguel. 2017. Unexpected Early Triassic marine ecosystem and the rise of the Modern evolutionary fauna. Science Advances 3:e1602159 [M. Clapham/M. Clapham]more details

Purpose of describing collection: general faunal/floral analysis

PaleoDB collection 202145: authorized by Val Syverson, entered by Val Syverson on 27.06.2019, edited by Matthew Clapham

Creative Commons license: CC BY (attribution)