Maastrichtian

EtymologyName formalityFormalUsage informationCelestial bodyEarthRegional usageGlobal (ICS)Time scale(s) usedICS Time ScaleDefinitionChronological unitAgeStratigraphic unitStageTime span formalityFormalLower boundary definitionMean of 12 biostratigraphic criteriaLower boundary GSSP, Landes, France
43°40′46″N1°06′48″W / 43.6795°N 1.1133°W / 43.6795; -1.1133Lower GSSP ratifiedFebruary 2001Upper boundary definitionIridium enriched layer associated with a major meteorite impact and subsequent K-Pg extinction event.Upper boundary GSSPEl Kef Section, El Kef, Tunisia
36°09′13″N8°38′55″E / 36.1537°N 8.6486°E / 36.1537; 8.6486Upper GSSP ratified1991

The Maastrichtian ( ) is, in the International Commission on Stratigraphy (ICS) geologic timescale, the latest age (uppermost stage) of the Late CretaceousEpoch or Upper CretaceousSeries, the CretaceousPeriod or System, and of the MesozoicEra or Erathem. It spanned the interval from 72.2 to 66 million years ago. The Maastrichtian was preceded by the Campanian and succeeded by the Danian (part of the Paleogene and Paleocene). It is named after the city of Maastricht, the capital and largest city of the Limburg province in the Netherlands.

The Cretaceous–Paleogene extinction event (formerly known as the Cretaceous–Tertiary extinction event) occurred at the end of this age. In this mass extinction, many commonly recognized groups such as non-avian dinosaurs, pterosaurs, plesiosaurs, and mosasaurs, as well as many other lesser-known groups, died out. The cause of the extinction is most commonly linked to an asteroid about 10 to 15 kilometres (6.2 to 9.3 mi) wide colliding with Earth, ending the Cretaceous.