The cause of the extinction is most commonly linked to an asteroid about 10 to 15 kilometres (6.2 to 9.3 mi) wide[4][5] colliding with Earth, ending the Cretaceous.

The Maastrichtian was introduced into scientific literature by Belgian geologist André Hubert Dumont in 1849, after studying rock strata of the Chalk Group close to the Dutch city of Maastricht.

A reference profile for the base was then appointed in a section along the Ardour river called Grande Carrière, close to the village of Tercis-les-Bains in southwestern France.

The biozones are (from young to old):[11] The Maastrichtian is roughly coeval with the Lancian North American Land Mammal Age.

North America was separated from Europe by rift basins, but sea floor spreading had not yet commenced between the two continents.

[13] Eruption of the Deccan Traps large igneous province began during the Maastrichtian, at around 67 million years ago.

At the same time, the Laramide orogeny drained the Western Interior Seaway of North America, further contributing to global cooling.

[15] Nonetheless, the latest Maastrichtian featured a sharp, pronounced warming,[16][17] which was caused by the activity of the Deccan Traps.