During the Cretaceous-Paleogene period (ca. 66 million years ago), a massive impact triggered an extinction-level event (ELE), wiping out about three-quarters of all plant and animal species on Earth, including the dinosaurs. Scientists have named the impactor that caused this devastation the Chicxulub meteor, after the nearby town of Chicxulub Pueblo in the Yucatan Peninsula in southern Mexico. The impact certainly left its mark, forming a 180-km-wide (112 mi) crater buried beneath the surface and creating thousands of limestone sinkholes filled with water (known as cenotes).

Today, Earth scientists are closing in on the type of impactor that caused the Cretaceous-Paleogene (K–Pg) extinction event. According to the latest findings from an international team of researchers, it may have been a rare type of space rock known as a carbonaceous (CO) chondrite. As they describe in a paper recently published in Science Advances, an advanced nickel isotope analysis of samples from around the world allowed them to narrow down the composition of the Cretaceous-Palaeogene meteorite.

Asteroids and other "space rocks" are essentially material left over from the formation of the Solar System, roughly 4.5 billion years ago. These objects regularly enter Earth's atmosphere, with most burning up and others exploding in mid-air in what is known as an "airburst." However, larger impactors like the Chicxulub meteor, estimated at 10 to 15 km (6 to 9 mi) in diameter, have occasionally reached the surface, causing massive explosions that eject enough material into the stratosphere to block out sunlight and trigger a "nuclear winter."

By analyzing material left behind by the impact, and comparing it to other meteorites that have been recovered on Earth, scientists can determine where the impactor came from in the Solar System. This is precisely what postdoctoral researcher [Georgy V. Makhatadze] and his colleagues at the Institut de Physique du Globe attempted when conducting high-precision nickel-isotope measurements of clay samples that formed from the impact. These samples were gathered over several years from sites around the world.