This process, whereby species evolve rapidly to exploit empty ecospace, is known as adaptive radiation. In his memoir, The Voyage of the Beagle, Darwin noted, almost as if in awe, "One might ...

Weevils are a diverse group of herbivorous beetles (~62,000 species) with extremely divergent ... Losos, J. B. Adaptive radiation, ecological opportunity, and evolutionary determinism.

The story of the mammals is only one example of adaptive radiation, a process that has happened again and again, at scales both large and small, in evolutionary history.