One of the strongest lines of evidence of a meteor or comet impact in the late Cretaceous is

Question

Quizplus · Accepted Answer

A thin layer of iridium-enriched clay has been found in late Cretaceous fossil strata all over the world. Iridium is rare in Earth's crust but is common in meteorites and comets, making the discovery of this layer a strong indication of an extraterrestrial impact. The layer corresponds with the extinction of the dinosaurs and other species, providing further evidence that the impact was a major factor in the mass extinction event.

One of the Strongest Lines of Evidence of a Meteor