Lower Oligocene

The Rupelian is, in the geologic timescale, the older of two ages or the lower of two stages of the Oligocene epoch/series. It spans the time between 33.9 and 28.1 Ma. It is preceded by the Priabonian stage (part of the Eocene) and is followed by the Chattian stage.

The stage is named after the small river Rupel in Belgium, a tributary to the Scheldt. The Belgian Rupel Group derives its name from the same source. The name Rupelian was introduced in scientific literature by Belgian geologist André Hubert Dumont in 1850. The separation between the group and the stage was made in the second half of the 20th century, when stratigraphers saw the need to distinguish between lithostratigraphic and chronostratigraphic names.

The base of the Rupelian stage (which is also the base of the Oligocene series) is at the extinction of the foraminiferan genus Hantkenina. An official GSSP had not yet been assigned to the Rupelian in 2009.

The top of the Rupelian stage (the base of the Chattian) is at the extinction of the foram genus Chiloguembelina (which is also the base of foram biozone P21b).

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