Overview of End Cretaceous Extinctions☆
Although the end-Cretaceous extinction event goes by a variety of names in both the technical and popular literature (e.g., Cretaceous–Tertiary (K–T) mass extinction, K–T boundary extinction, Cretaceous–Paleocene (K–Pg) mass extinction, Cretaceous–Palaeogene (K–Pg) extinction), it is most closely associated with the uppermost Cretaceous System/Stage – the Maastrichtian – and, to a lesser extent, the lowermost Palaeogene Epoch/Age – the Danian. As such, any review of effects and causes that may (or may not) have occurred during this episode of Earth history must begin with a review of the stratigraphy of these two intervals, not only because this provides the temporal, environmental, geographic, and tectonic context within which the extinction event must be understood, but also because the study cause–effect associations in Earth history is, by definition, largely a stratigraphic exercise.