The first mammals were
A) large and diurnal.
B) small and nocturnal.
C) large and nocturnal.
D) small and crepuscular.

Question

Quizplus · Accepted Answer

The first mammals are believed to have evolved during the Mesozoic Era, alongside the dinosaurs. They were small and probably nocturnal, which allowed them to avoid competition with the larger diurnal reptiles. This also allowed them to take advantage of the unique ecological niches that opened up during the night.

The First Mammals Were