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The Cretaceous (IPA: / k r ɪ ˈ t eɪ ʃ ə s / krih-TAY-shəss) [2] is a geological period that lasted from about 143.1 to 66 million years ago (Mya). It is the third and final period of the Mesozoic Era, as well as the longest. At around 77 million years, it is the ninth and longest geological period of the entire Phanerozoic.
The Cretaceous is justly famous for its chalk; indeed, more chalk formed in the Cretaceous than in any other period in the Phanerozoic. [51] Mid-ocean ridge activity—or rather, the circulation of seawater through the enlarged ridges—enriched the oceans in calcium; this made the oceans more saturated, as well as increased the bioavailability ...
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.
c. 143.1 Ma – End of Jurassic and beginning of Cretaceous Period. c. 145 Ma – First mantises. c. 140 Ma – Earliest orb-weaver spiders evolve. c. 130 Ma – Laurasia and Gondwana begin to split apart as the Atlantic Ocean forms. First flowering plants. Earliest anglerfish.
July: Officer and Page published their book, The Great Dinosaur Extinction Controversy. [124] The 20 paper anthology Cretaceous Mass Extinctions: Biotic and Environmental Changes was published. The volume was edited by Keller and Macleod who continued to argue that foraminifera were not victims of a catastrophic mass extinction at the end of ...
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 Early Cretaceous (geochronological name) or the Lower Cretaceous (chronostratigraphic name) is the earlier or lower of the two major divisions of the Cretaceous. It is usually considered to stretch from 145 Ma to 100.5 Ma.
Microceratus (meaning "small-horned") is a genus of small ceratopsian dinosaur that lived in the Cretaceous period in Asia.It walked on two legs, had short front arms, a characteristic ceratopsian frill and beak-like mouth, and was around 60 cm (2.0 ft) long. [1]