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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.
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 Triassic is the first and shortest period of the Mesozoic Era and the seventh period of the Phanerozoic Eon. Both the start and end of the period are marked by major extinction events . [ 10 ] The Triassic Period is subdivided into three epochs: Early Triassic , Middle Triassic and Late Triassic .
In Europe, most of the Lower Triassic is composed of Buntsandstein, a lithostratigraphic unit of continental red beds. [ citation needed ] The Early Triassic and partly also the Middle Triassic span the interval of biotic recovery from the Permian-Triassic extinction event , the most severe mass extinction event in Earth's history.
Altaid Orogeny – Paleozoic Era; Uralian orogeny – Long series of linear deformation and mountain building events that raised the Ural Mountains during the Permian Period; Cimmerian and Cathaysian orogenies Active through Triassic and Jurassic Periods along south and southeast Asia. Dabie-Sulu orogeny – Mesozoic Era
The mountains of northwest Ireland were formed during the collision, as was the granite that is found in locations in Donegal and Wicklow. The Irish landmass was now above sea level and lying near the equator, and fossil traces of land-based life forms survive from this period.
Following the Permian–Triassic extinction event, the most devastating of all mass-extinctions, life recovered slowly.In the Middle Triassic, many groups of organisms reached higher diversity again, such as the marine reptiles (e.g. ichthyosaurs, sauropterygians, thallatosaurs), ray-finned fish and many invertebrate groups like molluscs (ammonoids, bivalves, gastropods).
The event marks the end of the Mesozoic Era and the beginning of the Cenozoic Era. [12] "Tertiary" being no longer recognized as a formal time or rock unit by the International Commission on Stratigraphy, the K-T event is now called the Cretaceous—Paleogene (or K-Pg) extinction event by many researchers.