Revisiting Chicxulub

Chicxulub impact


A new study, slated to appear in the upcoming issue of Science, brings significant geochronological evidence to bear on the impact extinction theory of the dinosaurs, first proposed in 1980 by father-son duo Walter and Luis Alavarez.

The Chicxulub crater in the Yucatán Peninsula of Mexico is the largest known impact structure on earth, stretching more than 110 miles across. New radiometric data place the impact within 33,000 years of one of the largest mass extinctions on record: the one which ended the reign of the dinosaurs. This dramatic upheaval, occurring ~66 MYA, is otherwise known as the K-Pg (Cretaceous–Paleogene) extinction event.

While an asteroid collision has been the prevailing theory for the last four decades, the latest precision dating settles the time coincidence of impact and species extinction. The K-Pg boundary and impact crater now coincide precisely. And while there were likely preexisting environmental rifts which may have been pushing certain ecosystems toward extinction, there is now little dispute that Chicxulub signaled the death knell for this idyllic era of life.

“…Renne and his colleagues have now discovered the Chicxulub impact and the end-Cretaceous mass extinction event happened no more than 33,000 years apart. These new findings, appearing in the Feb. 8 issue of the journal Science, support the idea that the extraterrestrial collision dealt the age of dinosaurs its death blow.”

Most likely the indentation of an asteroid or meteor six miles across, the Chicxulub crater serves as a sobering reminder of how the majority of life on earth was extinguished in a geologic instant. The most celebrated victims were the dinosaurs, but the event also saw the loss of most marine reptiles, many fish, more than half of all land plants and insects, and a veritable pavilion of other terrestrial and marine organisms–more than 75% of all species on earth.

The K-Pg event is of course but one of the more recent and severe of several other mass and smaller-scale extinction events on record since the genesis of life.

Chicxulub impact 2


External link: Chicxulub Asteroid Impact: The Dino-Killer That Scientists Laughed At

Feature image courtesy of