obsolete term for the geological period 66–2.58 million years ago
The Tertiary is an outdated geological term that scientists once used to describe the time period from about 66 million to 2.58 million years ago, when mammals diversified and became dominant on Earth following the extinction of dinosaurs. While geologists no longer officially use this term, it matters historically because it was central to how scientists organized and understood Earth's deep past for many decades.
AI-generated from the Wikipedia summary — may contain errors.
Etymology Name formalityInformal Usage information Celestial bodyEarth Regional usageRegional(?) Time scale(s) usedICS Time Scale (formerly) Formerly used byICS Definition Chronological unitPeriod Stratigraphic unitSystem Time span formalityInformal Lower boundary definitionK-Pg extinction event Lower boundary GSSPNone Lower GSSP ratifiedN/A Upper boundary definitionBeginning of the Quaternary glaciation Upper boundary GSSPNone Upper GSSP ratifiedN/A
The Tertiary (/ˈtɜːrʃəri/ TUR-shər-ee, US also /ˈtɜːrʃi.ɛri/ TUR-shee-err-ee) is an obsolete geologic period spanning 66 million to 2.6 or 1.8 million years ago. The period began with the extinction of the non-avian dinosaurs in the Cretaceous–Paleogene extinction event, at the start of the Cenozoic Era, and extended to the beginning of the Quaternary glaciation at the end of the Pliocene Epoch. The Tertiary has not been recognised by the International Commission on Stratigraphy (ICS) since the late 1980s, with the timespan of the Tertiary now being split into the earlier Paleogene and the more recent Neogene periods, though the term continues to be used in some scientific publications.
Discovered by embedding cosine similarity (sentence-transformers MiniLM, 384-dim).