Naturally, this conclusion met with quite a
lot of skepticism initially.
However, the search was on: Could we actually
locate an impact crater of appropriate size and
age to be associated with the mass extinction
65 million years ago?
In 1989 a 170km diameter semi-circle of sinkholes
was identified in the Yucatan Peninsula in
an area called Chicxulub.
http://www.lpl.arizona.edu/SIC/impact_cratering/Chicxulub/Discovering_crater.html