Thaynes Limestone


The Thaynes Formation is a geologic formation in Montana and Idaho. It preserves fossils dating back to the Triassic period, such as Ammonoidea, Actinopterygii, Actinistia, Conodonta, Gastropoda, Nautiloidea, Ichthyosauria and others. A diverse fauna known as the Paris Biota has been described from the Thaynes Formation.