Torre Sant'Andrea.jpg
Rock deposits from the Cenozoic Era (Torre Sant'Andrea, Salento, Italy)
Name formalityFormal
Nickname(s)Age of Mammals
Usage information
Celestial bodyEarth
Regional usageGlobal (ICS)
Time scale(s) usedICS Time Scale
Chronological unitEra
Stratigraphic unitErathem
Time span formalityFormal
Lower boundary definitionIridium enriched layer associated with a major meteorite impact and subsequent K-Pg extinction event.
Lower boundary GSSPEl Kef Section, El Kef, Tunisia
36°09′13″N 8°38′55″E / 36.1537°N 8.6486°E / 36.1537; 8.6486
Lower GSSP ratified1991
Upper boundary definitionN/A
Upper boundary GSSPN/A
Upper GSSP ratifiedN/A

The Cenozoic (/ˌsnəˈz.ɪk, ˌsɛn-/ SEE-nə-ZOH-ik, SEN-ə-;[1][2] lit.'new life') is Earth's current geological era, representing the last 66 million years of Earth's history. It is characterised by the dominance of mammals, birds and flowering plants, a cooling and drying climate, and the current configuration of continents. It is the latest of three geological eras since complex life evolved, preceded by the Mesozoic and Paleozoic. It started with the Cretaceous–Paleogene extinction event, when many species, including the non-avian dinosaurs, became extinct in an event attributed by most experts to the impact of a large asteroid or other celestial body, the Chicxulub impactor.

The Cenozoic is also known as the Age of Mammals because the terrestrial animals that dominated both hemispheres were mammals – the eutherians (placentals) in the northern hemisphere and the metatherians (marsupials, now mainly restricted to Australia and to some extent South America) in the southern hemisphere. The extinction of many groups allowed mammals and birds to greatly diversify so that large mammals and birds dominated life on Earth. The continents also moved into their current positions during this era.

The climate during the early Cenozoic was warmer than today, particularly during the Paleocene–Eocene Thermal Maximum. However, the Eocene to Oligocene transition and the Quaternary glaciation dried and cooled Earth.

  1. ^ "Cenozoic". Lexico UK English Dictionary. Oxford University Press. Archived from the original on 23 November 2021.
  2. ^ "Cenozoic". Merriam-Webster Dictionary.

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