Which era, characterized by the extinction of reptiles and the appearance of mammals, is considered significant in geological history?

I think you forgot to give the options along with the question. I am answering the question based on my knowledge and research. The Mesozoic era is the era that is characterized by the extinction of reptiles and the appearance of mammals and is considered significant in geological history. I hope the answer helps you.

D. china is one of the most active places, which could quite possibly mean more agriculture will happen.. and more war machi-    best of luck comrade.