The correlation between impact-derived ejecta and paleontologically defined extinctions at multiple locations around the globe leads us to conclude that the Chicxulub impact triggered the mass extinction that marks the boundary between the Mesozoic and Cenozoic eras ~65.5 million years ago.
Alvarez, L. W., Alvarez, W., Asaro, F., and Michel, H. V., 1980, Extraterrestrial cause for the Cretaceous Tertiary extinction: Science, v. 208, no. 4448, p. 1095-1108.
Hildebrand, A. R., Penfield, G. T., Kring, D. A., Pilkington, M., Camargo Zanoguera, A., Jacobsen, S. B., and Boynton, W. V., 1991, Chicxulub Crater; a possible Cretaceous/Tertiary boundary impact crater on the Yucatan Peninsula, Mexico: Geology, v. 19, no. 9, p. 867-871.
Signor, P. W., and Lipps, J. H., 1982, Sampling bias, gradual extinction patterns, and catastrophes in the fossil record, Geological Implications of Impacts of Large Asteroids and Comets on the Earth: Special Paper - Geological Society of America, p. 291-296.