Impact event Chicxulub Crater. This crater is centered on the Yucatán Peninsula of Mexico and was discovered by Tony Camargo and Glen Pentfield while working as geophysicists for the Mexican oil company PEMEX. What they reported as a circular feature later turned out to be a crater estimated to be in diameter. This convinced the vast majority of scientists that this extinction resulted from a point event that is most probably an extraterrestrial impact and not from increased volcanism and climate change (which would spread its main effect over a much longer time period). Although there is now general agreement that there
Wilkes Land crater researchers led by Ralph von Frese and Laramie Potts of Ohio State University. The team used gravity measurements by NASA's GRACE satellites to identify a wide mass concentration and noted that this mass anomaly is centered within a larger ring-like structure visible in radar images of the land surface beneath the Antarctic ice cap. This combination suggested to them that the feature may mark the site of a wide impact crater buried beneath the ice and more than 2.5 times larger than the Chicxulub crater. Due to the site's location beneath the Antarctic ice sheet there are no direct samples