With "Tertiary" being discouraged as a formal time or rock unit by the International Commission on Stratigraphy, the K/T event is now called the Cretaceous–Palaeogene extinction event by many researchers. Gradstein F, Ogg J, Smith A. A geologic time scale 2004.{{cite book}}: CS1 maint: multiple names: authors list (link)
Schulte, Peter & others 2010. The Chicxulub asteroid impact and mass extinction at the Cretaceous–Paleogene Boundary. Science327 (5970): 1214–1218. [1]