According to scientists, 65.5 million years ago, when, falling on the Yucatan Peninsula, the asteroid destroyed the Mesozoic lizards, more than 90% of the mammals that lived then disappeared from the face of the earth. This is described in an article published in the Journal of Evolutionary Biology.
According to Nicholas Longreach, representing the British University of Bath, it was previously believed that immediately after the catastrophe, mammals began to flourish, this event did not have a significant impact on their lives. But now it turned out that they suffered from the Cretaceous-Paleogene catastrophe even more than other groups of animals (for example, crocodiles, turtles or lizards), but after it turned out to be more ready to adapt to new living conditions.
Such a conclusion Longreach and his colleagues came after carrying out the species richness of North America shortly before the catastrophe and after it. In total, they counted approximately 59 species of large and small mammals that inhabited Appalachia and Laramidia (two halves of the future North America in the Cretaceous).An asteroid almost destroyed mammals.
As the scientist noted, it is very difficult to assess the extent of any extinctions, with the exception of modern ones, since in most cases the rarest and most vulnerable species die out. Due to their small numbers, it is very difficult to find their remains in the rocks and, accordingly, the entire extinction depth is also difficult to determine.
To greatly simplify this task, scientists simply compared the number of mammalian species in North America during the Mesozoic before and after the disaster. The result was unexpected. It turned out that only four of the fifty-nine species were able to survive the fall of the asteroid. In other words, about 93% of our distant relatives died out together with dinosaurs. And this percentage significantly exceeds the share of extinct species among other groups of animals.Reptiles have suffered less catastrophes from mammals
But how then could mammals become masters of the earth? According to Nicholas Longreach, the decisive factor was the high ability to adapt to new conditions and the conquest of empty niches. As a result, after only 300 thousand years (a negligible period of time by the standards of evolution), the number of species doubled.
In addition, the spread of mammals and their rapid restoration was facilitated by the fact that in different regions of the future continent extinction affected various species of animals. As a result, the species diversity among the surviving mammals and the "balance of power" were significantly different in different parts of North America, which, in the end, led to a further increase in diversity among these animals.