The K–T boundary is a geological signature, usually a thin band, dated to (65.5 ± 0.3) Ma. K is the traditional abbreviation for the Cretaceous period, and T is the abbreviation for the Tertiary period. The boundary marks the end of the Mesozoic era and the beginning of the Cenozoic era, and is associated with the Cretaceous–Tertiary extinction event, a mass extinction. With "Tertiary" being discouraged as a formal time or rock unit by the International Commission on Stratigraphy, the K–T extinction event is now called the Cretaceous–Paleogene (or K–Pg) event by many researchers.
- ^ "International Stratigraphic Chart" (pdf). International commission for Stratigraphy. 2008. http://www.stratigraphy.org/cheu.pdf. Retrieved on 2008-12-24.
- ^ Fortey, R (1999). Life: A Natural History of the First Four Billion Years of Life on Earth. Vintage. pp. 238–260. ISBN 978-0375702617.
- ^ Gradstein F, Ogg J, Smith A. A Geologic Time Scale 2004. http://www.cambridge.org/uk/catalogue/catalogue.asp?isbn=0521781426.
|Cretaceous–Tertiary extinction event|
|Proposed K-T boundary craters|
|Boltysh crater||Chicxulub Crater|
|Shiva crater||Silverpit crater|