Timeline of Cretaceous–Paleogene extinction event research

[4] Ideas that evolution might proceed along pre-ordained patterns or that evolutionary lineages might age, deteriorate, and die like individual animals became popular starting in the late 19th century, but were superseded by the Neo-Darwinian synthesis.

[6] Paleontologists began dabbling in the subject, proposing environmental changes during the Cretaceous like mountain-building, dropping temperatures or volcanic eruptions as explanation for the extinction of the dinosaurs.

Early in this phase, the pace of the extinctions and the potential role of the Deccan Traps volcanism in India were major subjects of interest.

In 1991, Alan Hildebrand and William Boynton reported the Chicxulub crater in the Yucatan Peninsula of Mexico as a probable impact site.

In 2010, an international panel of researchers concluded that impact best explained the extinction event and that Chicxulub was indeed the resulting crater.