Maastrichtian followed by Danian
The Maastrichtian ( ) is, in the ICS geologic timescale, the latest age (uppermost stage) of the Late Cretaceous Epoch or Upper Cretaceous Series, the Cretaceous Period or System, and of the Mesozoic Era or Erathem. It spanned the interval from 72.1 to 66 million years ago. The Maastrichtian was preceded by the Campanian and succeeded by the Danian (part of the Paleogene and Paleocene).The Cretaceous–Paleogene extinction event (formerly known as the Cretaceous–Tertiary extinction event) occurred at the end of this age.  In this mass extinction, many commonly recognized groups such as non-avian dinosaurs, plesiosaurs and mosasaurs, as well as many other lesser-known groups, died out. The cause of the extinction is most commonly linked to an asteroid about 10 to 15 kilometres (6.2 to 9.3 mi) wide colliding with Earth, ending the Cretaceous.