context: Mesozoic, or Mesozoic era, MZ (from Ancient Greek: μέσος “average” + “life”) is a geological era that lasted from 251.902 ± 0.024 million years ago to 66.0 million years ago (total about 186 million years) [1]. This era was first identified by British geologist John Phillips in 1841.
question: How long did the Mesozoic era last?
answers.text: 186 million years