The origin of the asteroid which, 66 million years ago, wiped out almost all the dinosaurs and wiped out three out of four species has been reconstructed: it is a so-called “CO chondrite”, an exceptionally rare type and among the oldest in the Solar System, dating back to around 4.6 billion years ago.
The study published in the journal discovered this Science Advances and led by the Paris Institute of Earth Physics (IPGP), which analyzed the thin layer of clay deposited around the world after the impact. However, the provenance of the meteorite remains uncertain: it could come from a remote region of the outer Solar System, or from the asteroid belt located between Mars and Jupiter.
A rare, sulfur-poor meteorite
«The carbonaceous chondrites of the Ornans class are not at all like the typical meteorites found in museum collections», comments Philippe Claeys of the Vrije Universiteit of Brussels, one of the authors of the research. «They contain many fewer volatile elements, particularly sulphur, than other classes of meteorites discovered on Earth so far. “Being hit by such a rare projectile from so far away really highlights how unlucky the dinosaurs were,” adds Claeys.
Not the sulphur, but the dust
Differences in the composition of such meteorites could also help understand how the impact caused such widespread destruction. Since CO chondrites contain relatively small quantities of sulphur, in fact, the data obtained suggest that this element was not the main cause of the catastrophe: the predominant role was probably played by the enormous quantities of debris and dust thrown into the atmosphere, which plunged the Earth into years of cold and darkness.