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Paleontology in Pennsylvania refers to paleontological research occurring within or conducted by people from the U.S. state of Pennsylvania. The geologic column of Pennsylvania spans from the Precambrian to Quaternary.〔 During the early part of the Paleozoic, Pennsylvania was submerged by a warm, shallow sea. This sea would come to be inhabited by creatures like brachiopods, bryozoans, crinoids, graptolites, and trilobites. The armored fish ''Palaeaspis'' appeared during the Silurian. By the Devonian the state was home to other kinds of fishes. On land, some of the world's oldest tetrapods left behind footprints that would later fossilize. Some of Pennsylvania's most important fossil finds were made in the state's Devonian rocks.〔 Carboniferous Pennsylvania was a swampy environment covered by a wide variety of plants. The latter half of the period was called the Pennsylvanian in honor of the state's rich contemporary rock record. By the end of the Paleozoic the state was no longer so swampy. During the Mesozoic the state was home to dinosaurs and other kinds of reptiles, who left behind fossil footprints. Little is known about the early to mid Cenozoic of Pennsylvania, but during the Ice Age it seemed to have a tundra-like environment. Local Delaware people used to smoke mixtures of fossil bones and tobacco for good luck and to have wishes granted. By the late 1800s Pennsylvania was the site of formal scientific investigation of fossils. Around this time ''Hadrosaurus foulkii'' of neighboring New Jersey became the first mounted dinosaur skeleton exhibit at the Academy of Natural Sciences in Philadelphia. The Devonian trilobite ''Phacops rana'' is the Pennsylvania state fossil. ==Prehistory== No Precambrian fossils are known from Pennsylvania. As such, the state's fossil record does not begin until the Paleozoic. During the early part of the Paleozoic, Pennsylvania was located near the eastern coast of a continent called Laurentia. Much of the nearby sea covered the state.〔 During the Late Ordovician Pennsylvania was home to brachiopods, bryozoans, crinoids, graptolites, mollusks, pelecypods, starfish, and trilobites.〔 During the following Silurian Period, the fish ''Palaeapsis bitruncata'' left remains in Perry County.〔 Devonian tetrapods left footprints near Warren in what was once regarded as the oldest evidence for a terrestrial vertebrate, although more recent finds of footprints from Poland currently hold the record.〔 Later Devonian strata preserve primitive fishes and more evidence for early tetrapods.〔 One important fossil site called Red Hill is found along a road cut in Clinton County. It preserves evidence of a floodplain environment that was dominated by the plant ''Archaeopteris''. The early tetrapod ''Hynerpeton'', an important transitional fossil, was described from Red Hill. The name of the following period, the Carboniferous means "coal-bearing".〔 This period has been nicknamed the "age of amphibians" or the "age of coal swamps".〔 During the Carboniferous period Laurentia joined with another continent called Gondwana. The combined supercontinent is called Pangaea. Also at this time, seawater withdrew from the state.〔 During the Mississippian, a primitive tetrapod left tracks in the Pottsville area.〔 A series of swamps formed where the sea once was.〔 The late Carboniferous Pennsylvanian flora of Pennsylvania included ''Annularia'', ''Cordaites'', ''Diplothemema'', ''Mariopteris'', ''Neuropteris'', ''Odontopteris'', possible ''Pecopteris orenulata'', ''Pecopteris pennaeformis'', ''Pecopteris plumosa'', ''Sphenophyllum'', and possible ''Sphenopteris''.〔 However, the swamps bearing these plants would dry up before the end of the Paleozoic era. A gap in the rock record spans the remainder of the Paleozoic after the end of the Carboniferous because local sediments were being eroded away faster than they were being deposited.〔 During the Mesozoic, Pangaea began to break apart. The geological forces responsible for the breakup formed large rift valleys in the eastern part of the state.〔 These areas of Pennsylvania were covered in huge lakes during the Late Triassic.〔 Many dinosaur tracks have been discovered in Pennsylvania. ''Atreipus'' tracks are known from the Late Triassic Lockatong Formation in Arcola, Gratersford, and Gwynnedd.〔 ''Grallator'' tracks have been discovered in the Late Triassic Passaic Formation in Schwenksville. ''Atreipus'' tracks are known from the same formation in Gratersford.〔 The Late Triassic New Oxford Formation is the only known source of dinosaur skeletal remains in Pennsylvania. A dinosaur called ''Galtonia gibbidens'' left behind some teeth in the Emigsville area. ''Rutiodon'' fossils were preserved in York County along the Little Conewago Creek. Also near Emigsville, two metoposaurs were preserved in what is now a copper mine.〔 There are few if any rocks from the ensuing Tertiary period of the Cenozoic era in Pennsylvania's geologic record. However, during the Pleistocene, glaciers covered much of the state. Those areas left uncovered formed a tundra dotted with sedges and willows.〔 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 Pennsylvania」の詳細全文を読む スポンサード リンク
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