Chicxulub impactor

The asteroid or comet that struck the Yucatán region about 66 million years ago, creating the Chicxulub crater and triggering the end-Cretaceous mass extinction.

Asteroid: A small rocky or metallic body orbiting the Sun, too small to be classified as a planet. The impactor is generally understood to have been an asteroid rather than a comet.
Cretaceous–Paleogene extinction event: A mass extinction about 66 million years ago that eliminated roughly three-quarters of Earth’s species. The impact is the leading cause of this abrupt global extinction.
Haiti impact spherules: Glass beads and related impact debris found in Haiti, deposited by the Chicxulub collision. These distant deposits record the impact’s ejecta beyond the crater region.
Asteroid family: A group of asteroids sharing similar orbits and compositions, usually produced by the breakup of a parent body. A proposed link to a distant asteroid family could explain the impactor’s origin.
Carbonaceous chondrite: A primitive stony meteorite containing abundant carbon-bearing compounds and hydrated minerals. Chemical signatures at the boundary resemble material from this meteorite class.
Non-avian dinosaurs: Dinosaurs other than birds, which disappeared at the end of the Cretaceous. Their extinction is the most familiar consequence of the impact-driven ecological collapse.
Hell Creek Formation: A fossil-bearing rock formation in the western United States spanning the latest Cretaceous and earliest Paleogene. Its fossils and boundary deposits document ecological change around the impact.
Comet: An icy Solar System body that releases gas and dust when heated near the Sun. Some impactor-origin arguments consider a comet, though evidence favors an asteroid.
Iridium anomaly: An unusually high concentration of the rare element iridium in rocks at the K–Pg boundary. The anomaly first suggested an extraterrestrial source for the boundary layer.
Ammonites: Marine cephalopods with coiled external shells that flourished for hundreds of millions of years. Ammonites vanished at the K–Pg extinction, alongside many other marine groups.

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