Mass extinctions among some groups of amniotes coincide with numerous and large diversifications in other closely related groups, says the study.

The research challenges commonly held views that support a relationship between the evolution of "key innovations" in a group and the rapid increase in its number of species.
"Our results go against many of the traditional predictions from evolutionary biology, and show that the scientific views about the relevance of key innovations should be carefully reconsidered," said study co-author Johannes Muller, professor at Museum fur Naturkunde in Berlin, Germany.
The study examined the issue of adaptive radiations among early amniotes, from 315 to 200 million years ago.
The concept of adaptive radiation is central to modern evolutionary biology. An adaptive radiation is an extremely rapid increase in the number of species in a group, often as a result of a key evolutionary innovation, which gives the group an advantage over its competitors or allows it to exploit a new resource.
Often, if the appearance of an evolutionary novelty coincides temporarily with a large increase in species richness, it is assumed that the innovation is responsible for this pattern.
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The results showed that usually, large differences in diversity between two closely related groups are not because more species evolve in the larger group, but rather because more species of the smaller group go extinct.
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Source-IANS