Dinosaur species declined before the asteroid hit the earth
Science and Technology Daily (Reporter Zhang Mengran) The British "Nature Communications" magazine recently published a new biological study that found that about 10 million years before the mass extinction event caused by the asteroid impact on the earth, non-bird dinosaur species had fallen into decline.
This research further reveals the root cause of the extinction of dinosaurs.
In the past, it was widely believed that an asteroid hit Chicxulub in Mexico, causing the extinction of non-avian dinosaurs 66 million years ago.
Since the 1990s, with the discovery of the Chicxulub crater 125 miles wide under the Gulf of Mexico, the hypothesis that planetary impacts caused the extinction of the dinosaurs has been further confirmed because the crater is the same age as the rock formation.
And just in March of this year, in a study led by the University of Texas at Austin, scientists clearly linked the extinction of dinosaurs to the planet that crashed into the earth 66 million years ago by finding the key evidence of meteorite dust in the impact crater. .
However, the question of whether the dinosaurs had fallen into decline before the impact is still inconclusive, and it is difficult to make an assessment based on the existing fossil records.
In view of this, Fabien Condamina, a scientist at the Institute of Scientific Evolution of the University of Montpellier, France, and his colleagues analyzed 1,600 dinosaur fossils and evaluated 6 families of dinosaurs (Ankylosaurus and Protoceratops). , Hadrosauridae, Benosauridae, Tetraodontidae, Tyrannosaurus) species formation and extinction.
The research team found that the diversity of non-bird dinosaurs has been declining since 76 million years ago.
They believe that this decline is related to the increase in the rate of extinction of older species, which may indicate a lack of evolutionary novelty, or that these dinosaurs have difficulty adapting to changing environments.
The research team also assessed the ecological and physical factors in this transition, emphasizing that the global cooling in the late Cretaceous period (100 million to 6,600 years ago) may have exacerbated the process of dinosaur extinction.
They also pointed out that because the hadrosaurs outperformed other species in species competition, the decline in the diversity of herbivorous dinosaurs may also be one of the reasons.
Scientists believe that the combination of these factors hindered the dinosaurs’ ability to recover after the Chicxulub impact and contributed to their extinction.