It has been believed that a wide range of dinosaur species lived around the world in the late Cretaceous period, just before their extinction 66 million years ago.
However, in recent times the suspicion has gained strength that dinosaurs were not enjoying their best moment, but had been in decline for a long time.
And in 1990 when they discovered the crater in the Yucatan they were able to find large concentrations of iridium on its surface. Today you cannot see the crater itself because it is underwater, but one visible result is the ring of cenotes in the surroundings. 🏝️
— Different Latitudes (@DLatitudes) July 29, 2022
The question raised, whether the dinosaurs were exterminated by the cosmic catastrophe in full splendor of biodiversity or, on the contrary, the catastrophe was only the final push that threw them into the abyss of extinction, seems to have been resolved by a new and revealing study.
A team made up of, among others, Fei Han, from the China University of Geosciences in Wuhan, and Qiang Wang, from the Institute of Vertebrate Paleontology and Paleoanthropology, under the Chinese Academy of Sciences, has found evidence to support the hypothesis that dinosaurs had a fairly poor biodiversity shortly before the asteroid fell and that this decline had started some time ago.
Most of the scientific data on the last days of the dinosaurs comes from North America.
Although some published studies suggest that dinosaur biodiversity there was good before the asteroid fell, more detailed research has suggested that dinosaurs were in decline, setting the stage for their later extinction.
The study authors examined the fossil record of dinosaurs in China, hoping to find out if this trend of declining biodiversity extended to Asia as well.