The Mesozoic Era is one of three geologic eras of the Phanerozoic eon. The ivision of time into eras dates back to Giovanni Arduino, in the 18th century, although his original name for the era now called the 'Mesozoic' was 'Secondary' (making the modern era the 'Tertiary'). Lying between the Paleozoic and the Cenozoic, Mesozoic means 'middle animals', derived from Greek prefix meso-/μεσο- for 'between' and zoon/ζωον meaning animal or 'living being'. It is often called the 'Age of the Dinosaurs', after the dominant fauna of the era.