Chicxulub: The asteroid that ended the age of dinosaurs

Chicxulub impact: The asteroid that changed life on Earth forever

A cosmic collision that ended the dinosaur era and reshaped the planet

Sixty-six million years ago, a city-sized asteroid slammed into Earth with cataclysmic force, forever altering the trajectory of life on the planet. Known as the Chicxulub impactor, this asteroid left behind a vast crater near the Yucatán Peninsula in Mexico and is widely believed to have triggered the Cretaceous–Palaeogene extinction event, which wiped out the dinosaurs and set the stage for the rise of mammals and birds.

The collision marked the end of the Cretaceous Period, bringing to a close nearly 200 million years of dinosaur dominance.

The asteroid impact that reshaped Earth

Estimated to be between 10 and 15 kilometers in diameter, the Chicxulub asteroid struck Earth at a velocity of 20 kilometers per second, hitting at an angle of 60 degrees—a trajectory optimal for maximizing environmental destruction.

Upon impact, massive quantities of rock from deep within Earth’s crust were ejected more than 25 kilometers into the atmosphere. The crater itself—now buried beneath layers of sediment—measures over 150 kilometers wide and was originally surrounded by a ring of mountains taller than the Himalayas.

The force of the collision vaporized rock and released sulphur-rich gases and fine particulates into the atmosphere, blocking out sunlight and causing a dramatic drop in global temperatures. This “impact winter” is estimated to have lasted up to 15 years, plunging the planet into prolonged darkness and disrupting photosynthesis.

The extinction that followed

At the time of the impact, Earth’s biosphere was ruled by dinosaurs, who had adapted to a wide variety of ecological niches. The Chicxulub event devastated ecosystems, wiping out an estimated 75% of all species, including virtually all non-avian dinosaurs.

The extinction paved the way for evolutionary shifts that would lead to the rise of mammals and the eventual emergence of modern birds—descendants of small, feathered dinosaurs that managed to survive.

Discovery and scientific debate

Though the Chicxulub crater was discovered in the 1960s by geologists working for Mexico’s state oil company Pemex, it wasn’t until 1990 that scientists definitively connected it to the end-Cretaceous extinction.

The asteroid hypothesis was first proposed in the late 1970s by physicist Luis Alvarez and his son, geologist Walter Alvarez, based on elevated levels of iridium—a rare element associated with asteroids—found in the geological boundary marking the extinction event.

However, not all researchers agree that the asteroid impact was solely responsible. Some argue that dinosaurs were already in decline due to volcanic activity, shifting climates, or ecological pressures, with the Chicxulub impact acting as the final blow rather than the root cause.

A second impact?

In 2022, scientists discovered a second crater—nine kilometers wide—off the coast of West Africa, formed around the same time as the Chicxulub impact. Some researchers speculate it may have been created by a fragment of the same asteroid, suggesting a more complex impact scenario that could have compounded the environmental damage.

A legacy written in stone

Named after the town of Chicxulub Pueblo near its center, the crater today lies buried under sediments and the waters of the Gulf of Mexico. Yet its legacy remains visible in the fossil record and in the very structure of modern ecosystems.

The Chicxulub impact was more than a planetary catastrophe—it was a pivotal moment that cleared the evolutionary stage for new life to flourish, ultimately leading to the rise of humans.

Stay tuned to The Horizons Times for more on the scientific discoveries shaping our understanding of Earth’s past—and its future.