The First 40 Million Years of Planktonic Foraminifera

We provide a biochronology of Jurassic planktonic foramininfera, using first order linkage to ammonite and nannofossil stratigraphy geochronology. This enigmatic understudied group microfossils occurred from middle Toarcian through Tithonian time, ~180 ~143 Ma; its origin is unknown. There are three genera: Globuligerina, Conoglobigerina Petaloglobigerina. The genus with smooth pustulose test surface texture appeared in (late Early Jurassic) Conoglobigerina, rough reticulate Oxfordian (early Late time. Petaloglobigerina, having petaloid last whorl one or more claviform twisted chambers evolved early Kimmeridgian time Globuligerina balakhmatovae. Biochronologic events for foraminifera most like First Common Appearance Last events. very appearance levels taxa not easily sampled detected. recognize stratigraphic eleven species across four postulated evolutionary lineages, calibrated Geologic Time Scale 2020. A faunal change, which well documented led the survival only taxon, likely Gobuligerina oxfordiana Tithonian.