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Permian–Triassic boundary at Frazer Beach in New South Wales, with the End Permian extinction event located just above the coal layer [2]. Approximately 251.9 million years ago, the Permian–Triassic (P–T, P–Tr) extinction event (PTME; also known as the Late Permian extinction event, [3] the Latest Permian extinction event, [4] the End-Permian extinction event, [5] [6] and colloquially ...
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.
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 archosaurian reptiles such as the dinosaurs, and of gymnosperms such as cycads, ginkgoaceae and araucarian conifers; a hot greenhouse climate; and the tectonic break-up of Pangaea.
Michael Ochs Archives/Getty Images"The Adventures of Ozzie and Harriet" typified America's middle class of several decades ago. Consider a classic-yet-hypothetical photo of grandpa in his work ...
The middle class contains about half of America, according to the Pew Research Center -- 50%, to be exact. Another 21% fall into the upper class and 29% are in the lower class. But what is the ...
The middle class has been shrinking. In 1971, 61% of American households were considered to be middle class, and that number has dropped to 50% three decades later, a Pew Research Center analysis...
[46] [48] During the Middle Triassic the scleractinian corals typical of modern oceans appeared. During the Triassic, corals were rare in North America. Nevertheless, some were present on the west coast, although these corals did not congregate into reefs. [49] Ichthyosaurs were one of the most important groups of marine reptiles during the ...
During the rifting, South America tore away from North America and headed southward. The ocean flooded into the opening between the two continents, forming the Gulf of Mexico. A record of this rifting event remains as an indelible mark on the landscape called Mississippi Embayment. It is this embayment that ripped the dramatic gap between the ...