The Paris biota is an exceptionally diverse Early Triassic (approximately 249 million years ago)[1] fossil assemblage described in 2017 from the Lower Shale Member of the Thaynes Group. It was first discovered in Paris Canyon, west of the town of Paris in Bear Lake County, southeastern Idaho, United States.[2] This biota was later also found in coeval and slightly younger beds in northeastern Nevada (Elko County) and Bear Lake and Caribou counties, southeastern Idaho.[3]
Age
The Paris biota was found in layers dating back to the earliest Spathian, a substage of the Olenekianstage of the Early Triassicepoch. The biostratigraphy is constrained by the presence of the ammonoidsTirolites and Bajarunia, and conodonts.[2][3] The Tirolites/Columbites beds are dated with 248.853±0.086 Ma.[1] The Paris biota was later also discovered in slightly younger beds in Immigrant Canyon, northeastern Nevada, associated with the ammonoid index fossilsProhungarites sp. and Neopopanoceras haugi, which point to a middle–late Spathian age.[3]
The preservation of Paris biota organisms is considered taxon-dependent, but is not fully understood.[5] The study of some fossils could be improved using synchrotron μXRF imaging.[6]
Most organisms of the Paris biota were described in a thematic issue of the journal Geobios in 2019,[7] but new taxa were also subsequently described.
In 2023, another diverse post-extinction biota was presented from South China, the Dienerian aged Guiyang biota,[8] which includes fossils belonging to twelve classes and 19 orders. The Early Triassic is generally considered as an environmentally unstable and diversity-poor interval,[2] highlighting the importance of the discovery of such diverse lagerstätten.
The following taxa (animals sorted by phylum) were either reported or described from the Paris biota (not listed are the foraminifera and conodonts, which have not yet been described):
^Brayard, Arnaud; Fara, Emmanuel; Escarguel, Gilles (2019). "Foreword for the thematic issue "The Paris Biota (Bear Lake County, Idaho, USA): an exceptional window on the Early Triassic marine life"". Geobios. 54: 1–3. Bibcode:2019Geobi..54....1B. doi:10.1016/j.geobios.2019.04.009. S2CID146125332.
^Dai, Xu; Davies, Joshua H.F.L.; Yuan, Zhiwei; Brayard, Arnaud; Ovtcharova, Maria; Xu, Guanghui; Liu, Xiaokang; Smith, Christopher P.A.; Schweitzer, Carrie E.; Li, Mingtao; Perrot, Morgann G.; Jiang, Shouyi; Miao, Luyi; Cao, Yiran; Yan, Jia; Bai, Ruoyu; Wang, Fengyu; Guo, Wei; Song, Huyue; Tian, Li; Dal Corso, Jacopo; Liu, Yuting; Chu, Daoliang; Song, Haijun (2023). "A Mesozoic fossil lagerstätte from 250.8 million years ago shows a modern-type marine ecosystem". Science. 379 (6632): 567–572. Bibcode:2023Sci...379..567D. doi:10.1126/science.adf1622. PMID36758082. S2CID256697946.