To determine this, a team of researchers from the Berlin Museum of Natural History and the University of Lincoln, in the United Kingdom, has examined the adaptive radiations that occurred in vertebrates between 315 and 200 million years ago, that is, the rapid increases in the number of species in certain groups of organisms, something that gives them an advantage over their competitors and allows them to cover ecological niches.
At that time in the history of the Earth, important climatic changes took place on a global scale that caused, according to experts, from the disappearance of equatorial forests and extremely long droughts to a notable reduction in ice cover at the South Pole. In this period, the greatest mass extinction occurred, known as the Permian-Triassic, about 252 million years ago. 95% of marine organisms and 70% of terrestrial vertebrates disappeared at that time.
Well, the results of this new trial, published in the journal Scientific Reports , suggest that the greater or lesser diversity of two groups of vertebrates related to each other is not due to a greater number of species evolving into the most diverse of them, but rather that they become more extinct in the one that is less so. In this sense, the appearance of a major evolutionary innovation would not encourage the proliferation of new species , but would serve as a buffer, so to speak, when there is a great extinction.
The researchers cite as an example the case of dicynodonts, mammalian herbivores that 270 million years ago developed a kind of horny beak devoid of teeth and the ability to move the lower jaw back and forth, allowing them to better process plants. However, these adaptations were not particularly conducive to diversification. This was especially true 10 million years later , when a minor extinction took place and these animals outnumbered their competitors.
