Chicxulub crater

A buried impact structure beneath Mexico’s Yucatán Peninsula, formed about 66 million years ago by an asteroid impact linked to the Cretaceous–Paleogene mass extinction.

Impact cratering: The formation of cavities and ejecta when an object strikes a planetary surface at high speed. The impact produced Chicxulub’s immense basin, uplifted center, and surrounding deposits.
K–Pg boundary: The geological boundary marking the transition from the Cretaceous Period to the Paleogene Period about 66 million years ago. Impact debris at this boundary links Chicxulub to the extinction interval.
Luis Alvarez: An American physicist who shared the 1968 Nobel Prize in Physics for work on elementary-particle physics. He co-proposed that an asteroid impact caused the boundary iridium anomaly and extinction.
Non-avian dinosaurs: Dinosaurs other than birds, which disappeared from the fossil record at the end of the Cretaceous. Their extinction is among the best-known biological consequences associated with Chicxulub.
Deccan volcanism hypothesis: The hypothesis that Deccan Traps eruptions contributed substantially to the environmental changes and extinction near the end of the Cretaceous. It assigns a larger causal role to volcanism than impact-centered accounts do.
Peak ring: A circular ridge of uplifted rock inside a large complex impact crater. Chicxulub’s buried peak ring records the collapse and rebound of its transient crater.
Iridium anomaly: An unusually high concentration of iridium in rocks at the Cretaceous–Paleogene boundary. The global iridium layer helped motivate the impact hypothesis later tied to Chicxulub.
Walter Alvarez: An American geologist whose research on the K–Pg boundary helped establish the impact-extinction hypothesis. His fieldwork with Luis Alvarez began the search for evidence of a global impact.
Ammonites: An extinct group of marine cephalopods with coiled shells, abundant in Mesozoic seas. Ammonites vanished at the K–Pg boundary alongside many other marine groups.
Gradual extinction: An interpretation in which extinction unfolds over an extended interval rather than as a sharply timed crisis. The abrupt boundary record and impact evidence challenge explanations based solely on gradual decline.

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