Where the dinosaur-killing impact occurred
The asteroid or comet that contributed to the extinction of the non-avian dinosaurs struck Earth approximately 66 million years ago near what is now the Yucatán Peninsula in Mexico. The impact formed the Chicxulub crater, a buried structure identified through geophysical data and drilling that spans roughly 180 kilometers. The location is offshore, near the town of Chicxulub, and evidence from global layers of sediment links this site to the mass extinction event.
How we know the impact location
Scientists recognized the Chicxulub structure in the late 1970s and early 1980s through magnetic surveys and gravity readings, then confirmed it with drilling in the 1990s and 2000s. Key evidence includes shocked quartz, microtektites, and a global iridium-rich layer that match the crater’s properties. This convergence of geophysical, geochemical, and stratigraphic data firmly places the impact at Chicxulub.
Crater outline and morphology
Chicxulub is a complex impact structure with a central peak ring and annular trough, now partly buried under sediment and ocean. Its diameter is approximately 180 km, and its offshore position near the coast has influenced interpretations of the event’s environmental effects. The structure lies within marine carbonates of the Yucatán Platform.
| Attribute | Verified Detail | Source Type |
|---|---|---|
| Crater diameter | ~180 km | Seismic and borehole data |
| Modern location | Yucatán Shelf, Gulf of Mexico | Geophysical surveys |
| Age of impact | 66.043 ± 0.011 Ma | Ar–Ar and U–Pb dating |
| Surface expression | Buried; nearshore towns mark rim | Sedimentology and mapping |
| Key evidence | Shocked quartz, global iridium layer | Impact geology studies |
The linked extinction evidence
The Chicxulub impact is tied to the Cretaceous–Paleogene (K–Pg) boundary by a globally distributed layer containing high iridium, soot, and spherules. These signals align with models showing atmospheric injection of dust and aerosols that caused prolonged darkness and cooling. Paleontological records show a rapid decline in species concurrent with this boundary, supporting the impact hypothesis.
Alternative and coeval factors
While the Chicxulub impact is the predominant trigger, extensive volcanism in the Deccan Traps occurred around the same time and may have stressed ecosystems. Research continues on how these events interacted, but the spatial and temporal match between Chicxulub and the extinction horizon remains the most consistently supported explanation.
Ongoing research and monitoring
New analyses of core samples, seismic data, and climate simulations refine impact effects and recovery timescales. Studies examine how the crater architecture influenced environmental responses, informing comparisons with other impact structures. Continued interdisciplinary work strengthens the link between this specific location and the end-Cretaceous biotic crisis.
Why the site matters today
Understanding Chicxulub improves hazard assessments for future impact events and informs planetary defense strategies. The site also serves as a natural laboratory for studying large impacts, shock metamorphism, and Earth system responses. Although no other crater of this size aligns with the extinction layer, Chicxulub remains the clearest geologic evidence of a catastrophe that reshaped life on Earth.