Mesozoic
Middle Phanerozoic era comprising Triassic, Jurassic and Cretaceous.
Language and route: English scientific compound from Greek. Nineteenth-century formation from Greek mésos and a life-related -zoic suffix.
Literal gloss: middle life
The name and its history
John Phillips · 1841
- What does the word literally mean?
- The middle life of Phillips’s three successive fossil assemblages, not ‘the middle of Earth history’.
- What did the original author mean?
- The fauna of the ‘middle life’ lay between Phillips’s older and younger fossil worlds.
- Why was the name needed?
- Phillips sought a transregional palaeontological grouping wider than any single rock formation.
- What evidence supported the original concept?
- Changes in characteristic marine and terrestrial fossils were used to correlate major regional successions.
- How has geology changed the concept?
- Its three formal periods are not the historical threefold Trias of the German Basin.
Further historical context
John Phillips’s 1841 tripartition contrasted fossil assemblages: Paleozoic (older), Mesozoic (intermediate) and Cainozoic (more recent). The scheme gave a faunal framework across regions whose rocks did not look alike.
The name Mesozoic was not coined to signify the three German lithostratigraphic divisions that gave Triassic its name.
Editorial qualification
No known contested attribution identified in this pass; source checks remain subject to peer review.
Related names
Paleozoic · Cenozoic · Triassic · Jurassic · Cretaceous · Fossil · Lithostratigraphy
Sources
- ICS International Chronostratigraphic Chart, 2026/06 — Current name, rank and numerical boundaries
- Phillips (1841), Figures and Descriptions of the Palaeozoic Fossils — Digitised original source for three life-based eras
- Morrell (2001), Genesis and geochronology: John Phillips — Historical analysis of Phillips’s 1841 era scheme