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Selected Paleozoic taxa of Illinois. Illustration of a fossil of the Carboniferous-Permian spider Arthrolycosa. Charles Emerson Beecher (1889). Fossil of the Middle-Late Ordovician giant trilobite Isotelus. Life restoration of the Carboniferous-Permian amphibian Phlegethontia.
1910–2020 [1] The history of Illinois may be defined by several broad historical periods, namely, the pre-Columbian period, the era of European exploration and colonization, its development as part of the American frontier, its early statehood period, growth in the 19th and 20th centuries, and contemporary Illinois of today.
Paleontology in Illinois refers to paleontological research occurring within or conducted by people from the U.S. state of Illinois. Scientists have found that Illinois was covered by a sea during the Paleozoic Era. Over time this sea was inhabited by animals including brachiopods, clams, corals, crinoids, sea snails, sponges, and trilobites.
This list of the Paleozoic life of Illinois contains the various prehistoric life-forms whose fossilized remains have been reported from within the US state of Illinois and are between 538.8 and 252.17 million years of age.
North American. Definition. Chronological unit. Age. Stratigraphic unit. Stage. The Pre-Illinoian Stage is used by Quaternary geologists for the early and middle Pleistocene glacial and interglacial periods of geologic time in North America from ~2.5–0.2 Ma (million years ago). [ 1]
Paleogeographic reconstruction showing the Illinois Basin area during the Middle Devonian period. [9] Almost all Silurian rocks in Illinois are deep-water limestone and dolomite deposits; reef habitats were common, and fossils of reef organisms are locally highly abundant, including corals, brachiopods, crinoids, stromatoporoids, and bryozoans. [6]
Lake Chicago. Map of middle stage of glacial Lake Chicago, USGS Report of 1915. Lake Chicago was a prehistoric proglacial lake that is the ancestor of what is now known as Lake Michigan, one of North America 's five Great Lakes. Formed about 13,000 years ago and fed by retreating glaciers, it drained southwest through the Chicago Outlet River.
Illinoian (stage) The Illinoian Stage is the name used by Quaternary geologists in North America to designate the Penultimate Glacial Period c.191,000 to c.130,000 years ago, during the late Middle Pleistocene (Chibanian), when sediments comprising the Illinoian Glacial Lobe were deposited. It precedes the Sangamonian Stage (corresponding to ...