Question

From approximately 240 to 66 million years ago, dinosaurs dominated most of the land habitats on Earth. Around 66 million years ago, most dinosaurs went extinct when an asteroid struck the Earth. Mammals, which were much smaller and lived primarily in underground habitats, were able to avoid extinction. Mammals then underwent an adaptive radiation to develop a wide variety of new species. Which statement best explains why the adaptive radiation of mammals was possible?
A.
New species were able to form because the change in environmental conditions increased the mutation rate of mammals.
B.
Populations of mammals were able to rapidly increase since the Earth had a single, large habitat after the asteroid hit.
C.
Mammals were able to diversify to make use of the variety of habitats that were previously occupied by dinosaurs.
D.
The loss of predation decreased the rate at which mammals became reproductively isolated from one another.

Answer 1

The correct answer is option C, that is, mammals were able to diversify to make use of the variety of habitats that were previously occupied by dinosaurs.

Adaptive radiation refers to the comparatively fast evolution of various species from a single common ancestor. Adaptive radiation usually takes place when a species enters a novel area and distinct traits influence its existence. An illustration of adaptive radiation is the progression of mammals after the annihilation of dinosaurs.