The Ypresian Stage was introduced in scientific literature by
Belgian geologist
André Hubert Dumont in 1850. The Ypresian is named after the
Flemish city of
Ypres in Belgium (spelled
Ieper in Dutch). The definitions of the original stage were totally different from the modern ones. The Ypresian shares its name with the Belgian
Ieper Group (French: ''Groupe d'Ypres''), which has an Ypresian age. The base of the Ypresian Stage is defined at a strong negative anomaly in
δ13C values at the
PETM. The official reference profile (
GSSP) for the base of the Ypresian is the Dababiya profile near the
Egyptian city of
Luxor. Its original
type section was located in the vicinity of Ieper. The top of the Ypresian (the base of the Lutetian) is identified by the first appearance of the
foraminifera genus Hantkenina in the fossil record. The Ypresian Stage overlaps the upper Neustrian and most of the Grauvian
European Land Mammal Mega Zones (it spans the
Mammal Paleogene zones 7 through 10.), the
Wasatchian and lower and middle
Bridgerian North American Land Mammal Ages, the
Casamayoran South American Land Mammal Age and the
Bumbanian and most of the
Arshantan Asian Land Mammal Ages. It is also coeval with the upper Wangerripian and lowest Johannian regional stages of
Australia and the Bulitian, Penutian, and Ulatisian regional stages of
California. == Notable geological formations ==