Why are dinosaurs extinct?

Dinosaurs disappeared from the face of the Earth about 65 million years ago – at the end of the Cretaceous. Together with them, marine reptiles (mosasaurs and plesiosaurs) and flying dinosaurs, a number of mollusks and algae died out. In total, 16% of families of marine animals and 18% of families of terrestrial vertebrates died. According to the most widespread theory, the cause of the “great extinction” was the impact caused by the fall of an asteroid or comet in the Mexican Yucatan Peninsula.

This hypothesis was based on data on the approximate correspondence between the time of extinction of most of the extinct dinosaur species and the time of formation of the Chicxulub crater (it is a trace from the fall of an asteroid about 10 km in size about 65 million years ago). Among many other versions – increased volcanic activity: a giant outpouring of magma between 68 and 60 million years ago.

A number of scientists believe that dinosaurs were exterminated by the first predatory mammals, destroying clutches of eggs and cubs; also a sharp drop in sea level, a sharp jump in the Earth’s magnetic field and other factors could have had an impact. Paleontologists from the University of Reading presented their version of the answer to the question. In a study published in the journal Proceedings of the National Academy, they argue that dinosaurs were already on their way to extinction when the meteorite hit.

The new theory is a combined one: it does not deny the influence of the asteroid, but assigns it a secondary role. According to scientists, the collision of a celestial object with the Earth and the subsequent changes only put an end to a process that had been going on for a long time.

Experts have compared the rate of emergence of new species and the rate of extinction of existing species of ancient dinosaurs. As soon as the last parameter is ahead of the first, extinction begins to occur. Based on large-scale calculations that included data on six hundred species of dinosaurs, it turned out that this trend was outlined about 80-75 million years ago – long before the formation of the Chicxulub crater.

However, scientists still do not know why this happened. The splitting of supercontinents, climate change, competition with other animals and so on could have contributed to the slow extinction of dinosaurs: that is, all those factors that are considered in the framework of other hypotheses, with the exception of the version of the fall of the asteroid.