Ìgbà Jùrásíkì

The Jurassic is a geologic period and system that extends from about 199.6 Mya (million years ago) to 145.5± 4 Mya, that is, from the end of the Triassic to the beginning of the Cretaceous. The Jurassic constitutes the middle period of the Mesozoic Era, also known as the Age of Reptiles. The start of the period is marked by the major Triassic–Jurassic extinction event. However, the end of the Jurassic Period did not witness any major extinction event. The start and end of the period are defined by carefully selected locations; the uncertainty in dating arises from trying to date these horizons.

Ìgbà Jùrásíkì

Ìgbà Jùrásíkì 199.6–145.5 ẹgbẹgbẹ̀rún ọdun sẹ́yìn PreЄ Є O S D C P T J K Pg N
Mean atmospheric O2 content over period duration	ca. 26 Vol %[1] (130 % of modern level)
Mean atmospheric CO2 content over period duration	ca. 1950 ppm[2] (7 times pre-industrial level)
Mean surface temperature over period duration	ca. 16.5 °C[3] (3 °C above modern level)
Key events in the Jurassic view • discuss • edit -200 — – -195 — – -190 — – -185 — – -180 — – -175 — – -170 — – -165 — – -160 — – -155 — – -150 — – -145 — – Cretaceous Triassic Jurassic Hettangian Sinemurian Pliensbachian Toarcian Aalenian Bajocian Bathonian Callovian Oxfordian Kimmeridgian Tithonian         J u r a s s i c  Mesozoic An approximate timescale of key Jurassic events. Axis scale: millions of years ago.

The chronostratigraphic term "Jurassic" is directly linked to the Swiss Jura Mountains. Alexander von Humboldt (*1769, † 1859) recognized the mainly limestone dominated mountain range of the Swiss Jura Mountains as a separate formation that was not at the time included in the established stratigraphic system defined by Abraham Gottlob Werner (* 1749, † 1817) and named it “Jurakalk” in 1795.^[4][5][6] The name “Jura” is derived from the celtic root “jor” which was Latinised into “juria”, meaning forest (i.e. “Jura” is forest mountains).^[4][5][7]