Ypresian

It spans the time between 56 and 47.8 Ma, is preceded by the Thanetian Age (part of the Paleocene) and is followed by the Eocene Lutetian Age. The Ypresian is consistent with the lower Eocene.

Ypresian
56.0 – 47.8 Ma PreꞒ Ꞓ O S D C P T J K Pg N
Earth ~50 mya
Klondike Mountain Formation, Republic, Washington
Chronology
−65 — – −60 — – −55 — – −50 — – −45 — – −40 — – −35 — – −30 — – −25 — – M Z C e n o z o i c K P a l e o g e n e N L K P a l e o c e n e E o c e n e O l i g o c e n e M C Maastricht. Danian Selandian Thanetian Ypresian Lutetian Bartonian Priabonian Rupelian Chattian Aquitanian         ← PETM ← First Antarctic permanent ice-sheets ← K-Pg mass extinction Subdivision of the Paleogene according to the ICS, as of 2021. Vertical axis scale: millions of years ago
Formerly part of	Tertiary Period/System
Etymology
Name formality	Formal
Usage information
Celestial body	Earth
Regional usage	Global (ICS)
Time scale(s) used	ICS Time Scale
Definition
Chronological unit	Age
Stratigraphic unit	Stage
First proposed by	Dumont
Time span formality	Formal
Lower boundary definition	Strong negative anomaly in δ13C values at the PETM
Lower boundary GSSP	Dababiya section, Luxor, Egypt 25°30′00″N 32°31′52″E / 25.5000°N 32.5311°E / 25.5000; 32.5311
Lower GSSP ratified	2003
Upper boundary definition	FAD of the calcareous nannofossil Blackites inflatus
Upper boundary GSSP	Gorrondatxe section, Western Pyrenees, Basque Country, Spain 43°22′47″N 3°00′51″W / 43.3796°N 3.0143°W / 43.3796; -3.0143
Upper GSSP ratified	April 2011

The Ypresian Age begins during the throes of the Paleocene–Eocene Thermal Maximum (PETM). The Fur Formation in Denmark, the Messel shales in Germany, the Oise amber of France and Cambay amber of India are of this age. The Eocene Okanagan Highlands are an uplands subtropical to temperate series of lakes from the Ypresian.

The Ypresian is additionally marked by another warming event called the Early Eocene Climatic Optimum (EECO). The EECO is the longest sustained warming event in the Cenozoic record, lasting about 2–3 million years between 53 and 50 Ma. The interval is characterized by low oxygen 18 isotopes, high levels of atmospheric pCO2, and low meridional thermal gradients. Biodiversity has been reported to have been significantly impacted by the conditions prevalent during the EECO. For instance, there were biotic turnovers among marine producers such as calcerous nannofossil among others etc.

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.