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Definition
The Cretaceous/Tertiary boundary (KT), also often called the Cretaceous/Paleogene (K/Pg) boundary, marks the contact between the Mesozoic and Cenozoic eras ∼ 65 Ma ago. The KT boundary is characterized by the last major mass extinction in Earth history that saw the demise of the non-avian dinosaurs along with 50% to 60% of the Earth fauna and flora.