According to the evolutionary timeline described in the textbook:

• Mesozoic Era (A) is known as the 'Age of Reptiles' where dinosaurs dominated. Birds also evolved during this era (III) .
• Cenozoic Era (C) is the era where mammals took over the earth after the extinction of dinosaurs, hence 'Age of Mammals' (IV) .
• Paleozoic Era (D) includes the periods (Devonian, Carboniferous) where jawless fish, fish with stout fins, and amphibians evolved and thrived (II) .
• Proterozoic Era (B) is an earlier era characterized by the appearance of the first cellular forms of life and early invertebrates (I) .