China News Service, Beijing, February 24 (Reporter Sun Zifa) The dinosaurs that once dominated the earth were wiped out by an asteroid impact 66 million years ago, and the era of dinosaurs ended.
This remarkable event in the history of Earth's evolution happened in which season, spring, summer, autumn and winter?
A newly published evolution research paper in the internationally renowned academic journal "Nature" believes that the Chicxulub asteroid impact event that ended the dinosaur era (Mesozoic) occurred in the spring of the northern hemisphere.
The findings help explain subsequent extinction patterns and advance understanding of this pivotal moment in Earth's history.
Artistic rendering of the asteroid impact event (Credit: Joscha Knüppe).
Photo courtesy of Springer Nature
According to the paper, about 66 million years ago, a huge asteroid hit the Yucatan Peninsula in what is now Mexico, causing a mass extinction that killed 76% of Earth's species, including non-avian dinosaurs, pterosaurs and ammonites.
Previous studies of the timing of this event have focused on the millennium scale, so the season of the impact is unknown.
To address this issue, corresponding author Melanie During, Uppsala University, Sweden, and collaborators studied the filter-feeding sturgeon-shaped fishes (Sturgeonidae and Cystidae) that died en masse at the time of the impact event. The remains of fossils, unique three-dimensional growth patterns are visible in the well-preserved fossils, providing a record of seasonal changes.
Their analysis, combined with carbon isotope data, showed that the fish died in spring in the northern hemisphere.
The corresponding author of the paper excavated a spoonnose sturgeon in the sediment (Credit: Jackson Leibach).
Photo courtesy of Springer Nature
The fish fossils, found in late Cretaceous sediments in North Dakota, U.S., had impact debris in their gills but did not penetrate deep into the digestive system, suggesting that the fish were caught in an impact-triggered lakequake (land water shaking under impact), the authors of the paper said. ) died almost immediately in a sudden surging upstream of the river.
The catastrophe occurred in spring, a sensitive period for many northern hemisphere species to reproduce and raise their young.
The authors of the paper also mentioned that at the time, the southern hemisphere ecosystem was in a period of autumn stagnation, and the subsequent recovery rate was nearly twice that of the northern hemisphere.
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