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Cretaceous graphical timeline −140 — – ... Subdivision of the Cretaceous according to the ICS, as of 2023. [1] Vertical axis scale: Millions of years ago.
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 ...
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]
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 ...
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 Mesozoic Era [3] is the era of Earth's geological history, lasting from about , comprising the Triassic, Jurassic and Cretaceous Periods.It is characterized by the dominance of gymnosperms such as cycads, ginkgoaceae and araucarian conifers, and of archosaurian reptiles such as the dinosaurs; a hot greenhouse climate; and the tectonic break-up of Pangaea.
[1] in the Upper Cretaceous Period (mid to late Campanian), from 86.3 to 70.6 million years ago. [2] Maiasaura peeblesorum is the state fossil of Montana. The first remains of Maiasaura peeblesorum were discovered in the Two Medicine Formation near Chouteau, Montana in 1978 by Bynum, Montana resident Laurie Trexler. This holotype specimen was ...