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|“||It is very different world. The Himalayas do not yet exist, and the Atlantic is only half as wide. There's no grass, only conifer forests and fern prairies. This is a world ruled by dinosaurs!||”|
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Geology and ClimateEdit
The beginning of the Cretaceous was marked by a drought, followed by a rapid rise of the sea levels - one of the biggest in Earth's history - followed by a fall in the sea levels, due to a small-scale Ice Age. The seas of the Cretaceous were dominated by mollusks, Ammonites and Belemnites, bivalves and gastropods. Bony fish were wide-spread too, the reptiles continued to dominate on land, in the sea and in the air, but first true birds have also appeared, as did the mammals, both marsupial (i.e. Didelphodon) and placental (i.e. Purgatorius).The first flowering plants also appeared during the Cretaceous time period, as their evolution was tied to the evolution of insects and other animal pollinators. At the same time, Cretaceous was marked by an equal large percentage of extinctions. By the end of this time period, all of the ammonites and almost all of belemnites, many of the Mesozoic dinosaurs (besides the birds), marine reptiles, pterosaurs, multituberculate mammals. Among the plants many species of cycads, ginkgoes, seaweed, other plants perished as well. This was all due to the mass K-T extinction.
K-T Extinction EventEdit
at the end of this period, there was a mass extinction commonly referred to as the Cretaceous–Paleogene extinction event, as well the Cretaceous–Tertiary extinction event. At this extinction event, many commonly recognized groups such as non-avian dinosaurs, plesiosaurs and mosasaurs, as well as many other lesser known groups, died out.