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How precisely can scientists date the Cretaceous-Paleogene boundary?

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Cretaceous paleogeography — Cretaceous Period Distribution of landmasses, mountainous regions, shallow seas, and deep ocean basins during the late Cretaceous Period. Included in the paleogeographic reconstruction are the locations of the interval's subduction zones.

Scientists estimate the age of the Cretaceous-Paleogene (K-Pg) boundary—formerly known as the K-T boundary—to be approximately 66 million years ago.12

Determining the precise timing of this boundary remains a significant challenge in geochronology. Even when utilizing the most advanced radiometric dating techniques, researchers face a margin of error on the order of 50,000 years. Because geologic time is measured through various methods—including radiometric dating, paleomagnetic analysis, and the study of fossil content—pinpointing an "instantaneous" event in the geologic record is rarely possible with absolute precision.1

While the boundary is formally defined by a Global Boundary Stratotype Section and Point (GSSP) in Tunisia, which serves as a critical reference point for global correlation, the inherent limitations in measuring geologic time mean that the exact duration of the associated extinction event remains undetermined.12