Question

in which era did mammals emerge?
cenozoic
mesozoic
paleozoic
precambrian

Explanation:

Mammals first emerged during the Mesozoic era. While they were relatively small and not as dominant as dinosaurs during this time, they had their beginnings then. The Cenozoic era is when mammals diversified and became more prominent. The Paleozoic era predates the appearance of mammals, and the Precambrian is even earlier and long - before the evolution of mammals.

Answer:

B. Mesozoic