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The Phanerozoic is divided into three eras: the Paleozoic, Mesozoic and Cenozoic, which are further subdivided into 12 periods. The Paleozoic features the evolution of the three most prominent animal phyla, arthropods , molluscs and chordates , the last of which includes fish , amphibians and the fully terrestrial amniotes ( synapsids and ...
The Precambrian (/ p r i ˈ k æ m b r i. ə n,-ˈ k eɪ m-/ pree-KAM-bree-ən, -KAYM-; [2] or Pre-Cambrian, sometimes abbreviated pC, or Cryptozoic) is the earliest part of Earth's history, set before the current Phanerozoic Eon. The Precambrian is so named because it preceded the Cambrian, the first period of the Phanerozoic Eon, which is ...
c. 538.8 ± 0.6 Ma – beginning of the Cambrian Period, the Paleozoic Era and the current Phanerozoic Eon. End of the Ediacaran Period, the Proterozoic Eon and the Precambrian Supereon. The Ediacaran fauna disappears, while the Cambrian explosion initiates the emergence of most forms of complex life, including vertebrates ( fish ), arthropods ...
Grand Canyon National Park, Arizona, National Park Service, Grand Canyon National Park, Arizona. Seeley, J.M. (1999) Delineation of Proterozoic Unkar Group / Chuar Group (Grand Canyon Supergroup) Sedimentary Basin Deposits in Northern Arizona Using Gravity and Magnetic Geophysical Techniques. Publications, John M. Seeley Consulting, Casper ...
There are six notable meteorite or comet impact craters in Saskatchewan. Carswell, Deep Bay, and Gow Lake have affected the Canadian Shield area of the north. In the southern Phanerozoic crater are the Viewfield, Elbow, and Maple Creek structures. [18] The Carswell structure is the largest astrobleme at 35 kilometres (22 mi) in diameter. [33]
This latter solution predicts that break-up was confined to the Ediacaran period and produced the dramatic environmental changes that characterised the transition between the Precambrian and Phanerozoic. However, this theory has been widely criticized, as incorrect applications of paleomagnetic data have been pointed out. [20]
The Phanerozoic eon began following the Precambrian. The first major unit of time it contained was the Cambrian period of the Paleozoic era. [6] At the time, Earth's continents were in a very different arrangement and were generally smaller than they are today.
It is preceded by the Archean and followed by the Phanerozoic, and is the most recent part of the Precambrian "supereon". The Proterozoic is subdivided into three geologic eras (from oldest to youngest): the Paleoproterozoic , Mesoproterozoic and Neoproterozoic . [ 7 ]