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Paleontology in Oklahoma refers to paleontological research occurring within or conducted by people from the U.S. state of Oklahoma. Oklahoma has a rich fossil record spanning all three eras of the Phanerozoic Eon.〔 Oklahoma is the best source of Pennsylvanian fossils in the United States due to having an exceptionally complete geologic record of the epoch.〔 From the Cambrian to the Devonian, all of Oklahoma was covered by a sea that would come to be home to creatures like brachiopods, bryozoans, graptolites and trilobites. During the Carboniferous, an expanse of coastal deltaic swamps formed in areas of the state where early tetrapods would leave behind footprints that would later fossilize. The sea withdrew altogether during the Permian period. Oklahoma was home a variety of insects as well as early amphibians and reptiles. Oklahoma stayed dry for most of the Mesozoic. During the Late Triassic, carnivorous dinosaurs left behind footprints that would later fossilize. During the Cretaceous, however, the state was mostly covered by the Western Interior Seaway, which was home to huge ammonites and other marine invertebrates. During the Cenozoic, Oklahoma became home to creatures like bison, camels, creodonts, and horses. During the Ice Age, the state was home to mammoths and mastodons. Local Native Americans are known to have used fossils for medicinal purposes. The Jurassic dinosaur ''Saurophaganax maximus'' is the Oklahoma state fossil. ==Prehistory== No Precambrian fossils are known from Oklahoma, and the state's fossil record begins in the Paleozoic.〔 From the Cambrian to the Devonian, Oklahoma was covered by a sea.〔 Cambrian life of Oklahoma included graptolites and trilobites in the area now surrounding Turner Falls in the Arbuckle Mountains, although fossils are relatively scarce.〔 Oklahoma's Ordovician life included several species of brachiopods, bryozoans, primitive echinoderms, and ostracods.〔 Their remains fossilized at Rock Crossing in the Criner Hills of southern Oklahoma. One common Oklahoman graptolite was ''Climacograptus''. High quality specimens of the trilobite ''Isotelus'' were preserved southwest of Ardmore.〔 During the Silurian, Oklahoma was home to brachiopods, bryozoans, the trilobite ''Calymene'', echinoderms, and sponges, all of which left their remains south of Lawrence Creek.〔 However, the best sources of Silurian fossils in Oklahoma are "the northern flanks of the Arbuckle Mountains".〔 Oklahoma was home to an extremely diverse Devonian fauna in the Lawrence and White Mound areas.〔 During the Mississippian, Oklahoma's local fauna included ''Archimedes'', brachiopods, conodonts, echinoderms, the blastoid ''Pentremites'', and trilobites. Contemporary brachiopod families included the productids and rhynchonellida. The best source of Mississippian fossils in Oklahoma is the state's northeastern region.〔 During the Carboniferous, Oklahoma was a terrestrial environment characterized by vast river systems and accompanying deltas. These deltas were home to vast swamps responsible for leaving behind many coal deposits.〔 During the Carboniferous, early tetrapods left behind footprints that would later fossilize.〔 Oklahoma's diverse Pennsylvanian life included blastoids, brachiopods, bryozoans, fusulinids, and pelecypods.〔 Vertebrates included paleoniscid fishes, and the primitive tetrapods responsible for leaving contemporary footprints that would later fossilize.〔 Occasionally during this period, sea levels would rise and cover the state again.〔 This sea gradually retreated from the state before the end of the Paleozoic era. At this time, Oklahoma was home to amphibians, insects, and reptiles. Footprints laid down at this time would later fossilize.〔 Permian Oklahoma was relatively unchanged from its Pennsylvanian state.〔 Contemporary wildlife of Logan, Noble, Grant, and Garfield Counties included branchiopods, insects, and stegocephalian amphibians.〔 The giant Permian foraminiferan ''Pseudoschwagerina'' was preserved in the Pawnee area.〔 Other Permian fossils of Oklahoma were preserved in the north-central region of the state's Kay, Pawnee, and Payne Counties.〔 Oklahoma was a terrestrial environment for most of the ensuing Mesozoic era.〔 The Late Triassic Dockum Group of western Oklahoma preserved both reptile and amphibian remains, although its fossil record is scanty.〔 During the Late Triassic, small carnivorous dinosaurs left behind tracks near Kenton now classified in the ichnogenus ''Grallator''. The sediments preserving these tracks later became the Sheep Pen Sandstone.〔 Other local tracks have been referred to ''Chirotherium'', but Martin G. Lockley and Adrian Hunt have speculated that these might actually be ''Pseudotetrasauropus''.〔 The Late Jurassic fossiliferous Morrison Formation is exposed in the western part of the state.〔 Most of Oklahoma was submerged under the Western Interior Seaway during the Cretaceous.〔 Early Cretaceous life included "immense" ammonites, echinoids, and pelecypods. These fossils were preserved in Love and Marshall counties. The Late Cretaceous rocks of Bryan, Choctaw, and McCurtain counties bear abundant oysters like ''Exogyra'' and ''Ostraea''.〔 As the Rocky Mountains rose during the early Cenozoic, rivers drained off them and into Oklahoma. Sediments deposited by these rivers would preserve petrified wood and mammal fossils.〔 Sediments were generally being eroded away from Oklahoma during the later portion of the Cenozoic.〔 The High Plains of the western part of Oklahoma preserve evidence for the presence of camels, creodonts, and horses during the Pliocene.〔 During the ensuing Pleistocene epoch, resident animals included mammoths and mastodon. Their fossils were preserved in several different regions of Oklahoma. Typical Oklahoman proboscidean fossils are teeth and tusks, often preserved in gravel pits, but complete skeletons are also known.〔 Other mammals found in Pleistocene Oklahoma included ''Glyptotherium'', a large, heavily armored mammal related to the armadillo.〔(【引用サイトリンク】title=Glyptotherium Osborn 1903 (placental) )〕 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Paleontology in Oklahoma」の詳細全文を読む スポンサード リンク
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