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Cretaceous Period
145–66 million years aby
Mean atmospheric O
content ower period duration
c. 30 vol %
(150 % o modren level)
Mean atmospheric CO
content ower period duration
c. 1700 ppm
(6 times pre-industrial level)
Mean surface temperatur ower period duration c. 18 °C
(4 °C abuin modren level)
Key events in the Cretaceous
-140 —
-130 —
-120 —
-110 —
-100 —
-90 —
-80 —
-70 —
An approximate timescale of key Cretaceous events.
Axis scale: millions of years ago.

The Cretaceous is a geologic period an seestem that spans 79 million years frae the end o the Jurassic Period 145 million years ago (Mya) tae the beginnin o the Paleogene Period 66 Mya. It is the last period o the Mesozoic Era, an the langest period o the Phanerozoic Eon.[1] The Cretaceous Period is uisually abbreviatit K, for its German translation Kreide (cauk, creta in Laitin).[2]

The Cretaceous wis a period wi a relatively wairm climate, resultin in heich eustatic sea levels that creatit numerous shallae inland seas. Thir oceans an seas war populatit wi now-extinct marine reptiles, ammonites an rudists, while dinosaurs conteena'd tae dominate on laund. In this time, new groups o mammals an birds, as weel as flouerin plants, appeared.[1][2]

The Cretaceous (alang wi the Mesozoic) endit wi the Cretaceous–Paleogene extinction event, a muckle mass extinction in that mony groups, includin non-avian dinosaurs, pterosaurs an muckle marine reptiles dee'd oot. The end o the Cretaceous is defined bi the abrupt Cretaceous–Paleogene boondary (K–Pg boondary), a geologic seegnatur associatit wi the mass extinction that lies atween the Mesozoic an Cenozoic eras.[2]

References[eedit | eedit soorce]

  1. a b "What was the Cretaceous Period like?". www.nhm.ac.uk (in Inglis). Archived frae the original on 21 Juin 2023. Retrieved 11 Februar 2024.
  2. a b c "K–T extinction | Overview & Facts | Britannica". www.britannica.com (in Inglis). 29 Januar 2024. Archived frae the original on 31 December 2023. Retrieved 11 Februar 2024.