Final answer:
Mass extinctions caused by catastrophes like comets and asteroids can cause large-scale species loss, but also create opportunities for replacement species.
Step-by-step explanation:
Mass Extinctions and Species Replacement
Mass extinctions caused by cataclysmic events, such as comets and asteroids, can lead to large-scale loss of species. However, these catastrophes also create opportunities for new species to evolve and fill the ecological niches left behind. This results in a change in the type of species over time without a direct process of evolution. For example, after the mass extinction event that killed off many species 65 million years ago, mammals thrived and became dominant.