Program > By author > Aljahdali Mohammed

Planktonic foraminifera from the Rashrashiyah Formation of the Sirhan Basin in northern Saudi Arabia were examined for their biostratigraphy and stratigraphic ranges. Assemblages are well-preserved and diverse, with forty species and eleven genera. All samples are from the Priabonian Globigerinatheka semiinvoluta Highest Occurrence Zone (E14). The excellent preservation coupled with high diversity allows us to re-examine the stratigraphic ranges of many taxa. Our study reveals that several species of Globoturborotalita including G. barbula, G. cancellata, G. gnaucki, G. paracancellata, and G. pseudopraebulloides evolved earlier than previously proposed. Additionally, older stratigraphic occurrences are found for Dentoglobigerina taci and Subbotina projecta. Our revision to the stratigraphic ranges has implications for the phylogeny and indicates that the tropical/subtropical diversity of planktonic foraminifera in the late Eocene was higher than previous studies have documented.