It’s been the leading hypothesis for decades but finding the dust is a bit like finding the murder weapon:
Researchers believe they have closed the case of what killed the dinosaurs, definitively linking their extinction with an asteroid that slammed into Earth 66 million years ago by finding a key piece of evidence: asteroid dust inside the impact crater.
Death by asteroid rather than by a series of volcanic eruptions or some other global calamity has been the leading hypothesis since the 1980s, when scientists found asteroid dust in the geologic layer that marks the extinction of the dinosaurs…
In the 1990s, the connection was strengthened with the discovery of a 125-mile-wide Chicxulub impact crater beneath the Gulf of Mexico that is the same age as the rock layer. The new study seals the deal, researchers said, by finding asteroid dust with a matching chemical fingerprint within that crater at the precise geological location that marks the time of the extinction.
University of Texas at Austin, “Asteroid dust found in crater closes case of dinosaur extinction” at Phys.org
The paper is open access.
The asteroid theory replaced any number of folk Darwinian theories about why the dinosaurs died out. You know the sort of thing: They were too big; they were too stupid to look after their eggs; mammals ate their eggs… Etc. Many non-dinos went extinct too. Small mammals may have found it easier to hide.