One of the main reasons why mammals may have been able to evolve so quickly during the present era is due to the extinction of the main predators in the previous era. true or false

False, I'd say. Mammals usually adapt based on environment. Now, I know predators are "apart" of the environment, but I don't think that'd be it. I'd bet more money on saying mammals evolve based on environment adaptation. Sorry if I didn't answer your question or if I didn't get my point across well.