Paris biota

The Paris biota was found in layers dating back to the earliest Spathian, a substage of the Olenekian stage of the Early Triassic epoch. The biostratigraphy is constrained by the presence of the ammonoids Tirolites and Bajarunia, and conodonts. The Tirolites/Columbites beds are dated with 248.853±0.086 Ma. The Paris biota was later also discovered in slightly younger beds in Immigrant Canyon, northeastern Nevada, associated with the ammonoid index fossils Prohungarites sp. and Neopopanoceras haugi, which point to a middle–late Spathian age. ==Palaeogeography and paleoenvironment==

The organisms of the Paris biota lived in a shallow marine epicontinental sea (western USA basin) on the western coast of Pangea. The sites were located in a near-equatorial position during the Early Triassic epoch. ==Assemblage==

The Spathian aged Paris biota is one of the earliest diverse fossil assemblages from the post-extinction interval, about 3 million years after the Permian-Triassic mass extinction, and the first one in the wake of the Smithian-Spathian boundary extinction. The Paris biota comprises fossils belonging to 20 orders or seven phyla: (1) Retaria (foraminifers) The study of some fossils could be improved using synchrotron μXRF imaging. Most organisms of the Paris biota were described in a thematic issue of the journal Geobios in 2019, but new taxa were also subsequently described. In 2023, another diverse post-extinction biota was presented from South China, the Dienerian aged Guiyang biota, which includes fossils belonging to twelve classes and 19 orders. The Early Triassic is generally considered as an environmentally unstable and diversity-poor interval, 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): Sponges Brachiopods Mollusks Arthropods Echinoderms Chordates Algae ==See also==