Cretaceous–Paleogene boundary

E6899

chronostratigraphic boundary geological boundary mass extinction boundary

The Cretaceous–Paleogene boundary marks the geological transition 66 million years ago associated with a mass extinction event that wiped out non-avian dinosaurs and many other species, likely triggered by a large asteroid impact.

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All labels observed (11)

Label	Occurrences
Cretaceous–Paleogene extinction event	33
Cretaceous–Paleogene mass extinction	6
Cretaceous–Paleogene boundary canonical	5
Chicxulub impact event	2
Cretaceous–Paleogene boundary at Stevns Klint	1
Cretaceous–Paleogene boundary layer	1
Cretaceous–Tertiary boundary	1
Gubbio K–Pg boundary section in Italy	1
K–Pg boundary	1
K–Pg boundary layer	1
K–T boundary	1

How this entity was disambiguated

This entity first appeared as the object of triple T72256 — resolving that mention is where its identity was fixed. The disambiguator weighed these candidate entities and picked the highlighted one (or “None”, minting a new entity). This is how homonymy is resolved: the same surface form can point to different entities.

NED1 Entity disambiguation (via context triple) gpt-5-mini-2025-08-07

Target entity: Cretaceous–Paleogene boundary
Context triple: [Cretaceous, hasBoundaryEvent, Cretaceous–Paleogene boundary]

A. Cretaceous
The Cretaceous was the final period of the Mesozoic Era, marked by high sea levels, diverse dinosaurs, and ending with the mass extinction that wiped them out about 66 million years ago.
B. Pliocene epoch
The Pliocene epoch was a geological time period roughly 5.3 to 2.6 million years ago marked by cooler global climates, the expansion of grasslands, and significant evolutionary developments among mammals and early hominins.
C. Deccan Traps volcanism
Deccan Traps volcanism refers to one of Earth’s largest known volcanic flood basalt events in western India, linked to mass extinction and major climatic changes near the end of the Cretaceous period.
D. Jurassic
Jurassic is a geologic period of the Mesozoic Era known for its abundant dinosaurs and the breakup of the supercontinent Pangaea.
E. The Endangered Earth
The Endangered Earth is the collective representation of the planet’s environmental crisis, recognized by Time as a symbolic “Person of the Year” to highlight global ecological threats and the urgency of conservation.
F. None of above. chosen
G. Unsure - the case is ambiguous/there is not enough information to decide.

NED2 Entity disambiguation (via description) gpt-5-mini-2025-08-07

Target entity: Cretaceous–Paleogene boundary
Target entity description: The Cretaceous–Paleogene boundary marks the geological transition 66 million years ago associated with a mass extinction event that wiped out non-avian dinosaurs and many other species, likely triggered by a large asteroid impact.

A. Cretaceous
The Cretaceous was the final period of the Mesozoic Era, marked by high sea levels, diverse dinosaurs, and ending with the mass extinction that wiped them out about 66 million years ago.
B. Pliocene epoch
The Pliocene epoch was a geological time period roughly 5.3 to 2.6 million years ago marked by cooler global climates, the expansion of grasslands, and significant evolutionary developments among mammals and early hominins.
C. Deccan Traps volcanism
Deccan Traps volcanism refers to one of Earth’s largest known volcanic flood basalt events in western India, linked to mass extinction and major climatic changes near the end of the Cretaceous period.
D. Jurassic
Jurassic is a geologic period of the Mesozoic Era known for its abundant dinosaurs and the breakup of the supercontinent Pangaea.
E. The Endangered Earth
The Endangered Earth is the collective representation of the planet’s environmental crisis, recognized by Time as a symbolic “Person of the Year” to highlight global ecological threats and the urgency of conservation.
F. None of above. chosen

Statements (48)

Predicate	Object
instanceOf	chronostratigraphic boundary ⓘ geological boundary ⓘ mass extinction boundary ⓘ
age	about 66 million years ago ⓘ
alsoKnownAs	K–Pg boundary ⓘ linked to: Cretaceous–Paleogene boundary K–T boundary ⓘ linked to: Cretaceous–Paleogene boundary
associatedWith	Cretaceous–Paleogene extinction event ⓘ linked to: Cretaceous–Paleogene boundary extinction of ammonites ⓘ extinction of many marine reptiles ⓘ extinction of many plankton species ⓘ extinction of many terrestrial plant species ⓘ mass extinction of non-avian dinosaurs ⓘ
cause	large asteroid impact ⓘ
characterizedBy	abrupt faunal turnover ⓘ abrupt floral turnover ⓘ negative carbon isotope excursion in some sections ⓘ
correlatesWith	Chicxulub impact crater ⓘ
definedBy	first appearance of Paleogene fossils above boundary ⓘ last appearance of many Cretaceous taxa below boundary ⓘ
evidence	global iridium-rich clay layer ⓘ microtektites ⓘ shocked quartz ⓘ spherules from impact ejecta ⓘ
formerlyKnownAs	Cretaceous–Tertiary boundary ⓘ linked to: Cretaceous–Paleogene boundary
globalExtent	worldwide ⓘ
impactOn	evolution of mammals ⓘ radiation of birds ⓘ restructuring of marine ecosystems ⓘ restructuring of terrestrial ecosystems ⓘ
linkedTo	short-term global cooling followed by warming ⓘ sudden collapse of primary productivity in surface oceans ⓘ wildfires on a global or near-global scale ⓘ
locatedInTimeScale	International Chronostratigraphic Chart ⓘ
marksBeginningOf	Cenozoic Era ⓘ linked to: Cenozoic
marksEndOf	Mesozoic Era ⓘ
marksTransitionBetween	Cretaceous Period ⓘ linked to: Cretaceous Paleogene Period ⓘ linked to: Paleogene
ratifiedBy	International Commission on Stratigraphy ⓘ
recognizedBy	distinct boundary clay layer in many sections ⓘ
relatedTo	Deccan Traps volcanism ⓘ
scientificDebate	relative roles of impact and volcanism in extinction ⓘ
separates	Upper Cretaceous strata from lower Paleogene strata ⓘ
stratigraphicRank	system/period boundary ⓘ
timeEquivalentOf	Cretaceous–Paleogene extinction event ⓘ linked to: Cretaceous–Paleogene boundary
usedIn	biostratigraphy ⓘ chemostratigraphy ⓘ geochronology ⓘ magnetostratigraphy ⓘ

How these facts were elicited