The space rock that wiped out the dinosaurs 66 million years ago has been identified as an exceptionally rare CO chondrite (Carbonaceous Ornans) meteorite. A study published in Science Advances analyzed nickel isotopes preserved globally from the Cretaceous-Paleogene (K-Pg) boundary layer to pinpoint this unique classification.
Key Findings of the Discovery
▫️The Rock Classification: It was an ultra-rare carbonaceous meteorite originating from the cold, outer regions of our solar system.
▫️The Extinction Mechanism Shift: Because CO chondrites have very low concentrations of sulfur, carbon, and water, researchers believe the deadliest blow was delivered by planet-cooling fine dust and vaporized rock. This challenges the traditional theory that sulfur gas inside the asteroid was the "smoking gun".
▫️The Impact Event: The 6-to-9-mile-wide rock slammed into Mexico's Yucatán Peninsula, creating the massive, 112-mile-wide Chicxulub crater.
The Aftermath: "Charbroiled" Earth
Separate research published concurrently in the Journal of Geophysical Research: Biogeosciences sheds light on the devastating immediate timeline:
▫️Immediate Inferno: The collision vaporized thousands of cubic kilometers of rock, casting a thick, global blanket of fine dust into the sky.
▫️The Thermos Effect: This dust layer trapped rising thermal radiation, acting like a planetary grill that multiplied heat intensity by 3.5 times.
▫️Rapid Demise: Many land animals and dinosaurs may have been incinerated by widespread wildfires within just one to two hours of the impact.
This pair of breakthroughs resolves a decades-long mystery regarding both the physical identity of the Chicxulub impactor and the exact atmospheric physics that triggered the sudden extinction of 75% of Earth's species.
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