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Cretaceous period

Subdivision of the Cretaceous according to the ICS, as of 2024.Vertical axis scale: Millions of years agoEtymologyName formalityFormalUsage informationCelestial bodyEarthRegional usageGlobal (ICS)Time scale(s) usedICS Time ScaleDefinitionChronological unitPeriodStratigraphic unitSystemTime span formalityFormalLower boundary definitionNot formally definedLower boundary definition candidatesMagnetic—base of Chron M18rBase of Calpionellid zone BFAD of AmmoniteBerriasella jacobiLower boundary GSSP candidate section(s)NoneUpper boundary definitionIridium-enriched layer associated with a major meteorite impact and subsequent K-Pg extinction eventUpper boundary GSSPEl Kef Section, El Kef, Tunisia36°09′13″N8°38′55″E / 36.1537°N 8.6486°E / 36.1537; 8.6486Upper GSSP ratified1991The Cretaceous (IPA: ) is a geological period that lasted from about 143.1 to 66 Ma (million years ago).

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