Alan Russell Hildebrand (born 1955) is a Canadian planetary scientist and Associate Professor in the Department of Geoscience at the University of Calgary.
His work has shed light on the extinction event caused by the Chicxulub asteroid at the end of the Cretaceous period.
[3] He got a Ph.D. in Planetary Sciences at The University of Arizona under William Boynton in 1992 with the dissertation "Geochemistry and stratigraphy of the Cretaceous/Tertiary boundary impact ejecta".
[4] In 1978 the Chicxulub Crater in the Yucatan Peninsula of Mexico was discovered by Glen Penfield, but its significance was not recognized at the time.
In 1990, as part of his doctoral program, Hildebrand, working with the father-and-son team of Luis and Walter Alvarez, published controversial articles suggesting that a large impact from an asteroid caused the mass extinction at the end of the Cretaceous period.