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The Cretaceous was a period with a relatively warm climate, resulting in high eustatic sea levels that created numerous shallow inland seas. These oceans and seas were populated with now-extinct marine reptiles, ammonites, and rudists, while dinosaurs continued to dominate on land. The world was largely ice-free, although there is some evidence ...
Cretaceous graphical timeline −140 — – ... Subdivision of the Cretaceous according to the ICS, as of 2023. [1] Vertical axis scale: Millions of years ago.
Region in Russia where rocks from this period were first identified Triassic: c. 251.902 Ma: Lt. trias: triad: In Germany this period forms three distinct layers Jurassic: c. 201.4 Ma: Jura Mountains: Mountain range in the Alps in which rocks from this period were first identified Cretaceous: c. 143.1 Ma: Lt. creta: chalk: More chalk formed in ...
Smith and others concluded that the Late Cretaceous drop in sea levels constituted the most severe marine regression of the entire Mesozoic Era. [102] D'Hondt and others argued that an asteroid impact at the end of the Cretaceous would not have produced enough acid for acid rain to be a significant factor contributing to the mass extinction. [56]
The Late Cretaceous (100.5–66 Ma) is the younger of two epochs into which the Cretaceous Period is divided in the geologic time scale. Rock strata from this epoch form the Upper Cretaceous Series. The Cretaceous is named after creta, the Latin word for the white limestone known as chalk.
The elimination of dominant Cretaceous groups allowed other organisms to take their place, causing a remarkable amount of species diversification during the Paleogene Period. [29] After the K–Pg extinction event, biodiversity required substantial time to recover, despite the existence of abundant vacant ecological niches . [ 35 ]
The K–Pg boundary marks the end of the Cretaceous Period, the last period of the Mesozoic Era, and marks the beginning of the Paleogene Period, the first period of the Cenozoic Era. Its age is usually estimated at 66 million years, [2] with radiometric dating yielding a more precise age of 66.043 ± 0.043 Ma. [3]
This is an accepted version of this page This is the latest accepted revision, reviewed on 24 January 2025. Family of theropod dinosaurs Dromaeosaurids Temporal range: Cretaceous Pre๊ ๊ O S D C P T J K Pg N A collection of dromaeosaurid fossil skeletons. Clockwise from upper left: Deinonychus antirrhopus (a heavily built eudromaeosaur), Buitreraptor gonzalezorum (a long-snouted unenlagiine ...