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Paleontology in Wyoming refers to paleontological research occurring within or conducted by people from the U.S. state of Wyoming. The fossil record of Wyoming spans from the Precambrian to recent deposits. There are a large number of different fossil sites spread throughout the state.〔 Wyoming is such a spectacular source of fossils that author Marian Murray noted in 1974 that "()ven today, it is the expected thing that any great museum will send its representatives to Wyoming as often as possible."〔 Murray has also written that nearly every major vertebrate paleontologist in United States history has collected fossils in Wyoming.〔 Wyoming is a major source of dinosaur fossils.〔 Wyoming's dinosaur fossils are curated by museums located all over the planet.〔 During the Precambrian, Wyoming was covered by a shallow sea inhabited by stromatolite-forming bacteria. This sea remained in place during the early Paleozoic era and would come to be inhabited by creatures like brachiopods, ostracoderms, and trilobites. During the Silurian, the sea withdrew from Wyoming and there is a gap in the local rock record. During the Devonian the sea returned to the state and remained until the Permian when it started to withdraw once more. By the Triassic the state had become a coastal plain inhabited by dinosaurs whose footprints would later fossilize. By the Jurassic, the state was covered in sand dunes. The Western Interior Seaway submerged much of the state during the Late Cretaceous. During the early part of the Cenozoic, Wyoming was home to massive lakes inhabited by fish-like ''Knightia'' and dense forests. On land the state would come to be inhabited by camels, carnivorans, creodonts, the seven foot tall flightless bird ''Diatryma'', elephants, horses, primates, rodents, and ''Uintatherium''. During the Ice Age, Wyoming was subject to glacial activity. Local Native Americans have known about fossils for thousands of years and have both applied them to practical purposes and devised myths to explain them. Wyoming first became a hotspot for dinosaur research in the 1870s with the discovery of the dinosaurs preserved in the Morrison Formation. By the early 20th century, hundreds of tons of dinosaur fossils had been excavated from Wyoming. The Eocene fish ''Knightia'' is the Wyoming state fossil. ''Triceratops'' is the state dinosaur of Wyoming. ==Prehistory== During the Precambrian, Wyoming was covered by a shallow sea. Stromatolites formed there.〔 Some Precambrian stromatolites remain preserved in the Medicine Bow Mountains.〔 Some local geologic structures may be a record of the activities of other inhabitants of this sea preserved as trace fossils.〔 During the early part of the Paleozoic, Wyoming was still covered by a shallow sea. The state was home to brachiopods and trilobites at this time.〔 By the Late Cambrian, Wyoming was home to calcareous algae. Great masses of this algae were preserved in the Gros Ventre Formation. The area of Wyoming now characterized by the Bighorn Mountains was a marine environment during the Ordovician. Ostracoderms swam in this sea.〔 During the Silurian, the sea withdrew from Wyoming and local sediments were eroded away. During the Devonian, the sea returned to the state and remained until the Permian when it started to withdraw once more.〔 During the Triassic, Wyoming's sea continued its withdrawal. As the sea shrunk away, much of Wyoming was occupied by a coastal plain environment divided by rivers.〔 During the Late Triassic,〔 dinosaurs left behind small footprints in western Wyoming that would later fossilize. These tracks have been referred to the ichnospecies ''Agialopus wyomingensis''.〔 Some Triassic red beds in Wyoming preserve unusual "scrape mark" trace fossils that were likely left by a swimming animal. Similar tracks found in France have been attributed to turtles.〔 Into the Jurassic, much of the state was covered in sand dunes. Sea levels began to fluctuate again during the Jurassic. The sea was home to belemnites and oysters. On land dinosaurs left behind many footprints across the floodplains.〔 During the Jurassic, the area of Wyoming now called Dinosaur Canyon was home to primitive relatives of modern crocodilians and mammals.〔 Pterosaurs may have been responsible for footprints laid down in sediments now known as the Sundance Formation.〔 They are classified in the ichnogenus ''Pteraichnus''.〔 During the Cretaceous the state experienced an interval of mountain building activity called the Laramide Orogeny.〔 Most of Wyoming was submerged under a sea called the Western Interior Seaway during the Cretaceous.〔 One common inhabitant of Wyoming's Cretaceous Western Interior Seaway was ''Enchodus''. ''Enchodus'' was a relative of modern salmon and its long fangs earned it the misleading nickname "the sabre-toothed herring". Although dangerous looking, these fangs were likely used to trap small prey rather than pierce large game. ''Enchodus'' was so abundant that roughly one quarter of the fossils left in the state's Pierre Shale deposits are attributable to the genus.〔 ''Enchodus'' was preyed upon by ''Cimolichthys''.〔 ''Cimolichthys'' was another relative of modern salmon, but had a build similar to that of a barracuda or pike.〔 ''Cimolichthys'' was a fierce predator that hunted relatively large game. Sometimes its attempts to kill overly large prey would be its own doom. One ''Cimolichthys'' suffocated when its would-be prey, a sizable squid called ''Tusoteuthis longa'', was too large to swallow completely and blocked the fish's gills. Western Interior Seaway researcher Michael J. Everhart has called the specimen "()ne of the strangest 'death by gluttony' occurrences in the fossil record".〔 The plesiosaur ''Dolichorhynchops osborni'' was another inhabitant of Wyoming's Cretaceous sea. Its remains are more common in this state than in Kansas.〔 The sea turtle ''Toxochelys latiremis'' was also present. One specimen was associated with fossil feces preserving fish bones inside. If these feces really belonged to the ''Toxochelys'' the inclusion of fish in its diet would distinguish it from all modern sea turtles, none of which are known to eat fish.〔 During the Cretaceous, mammals were common in Wyoming and dinosaurs nested in the area around Powell.〔Late Cretaceous fossil dinosaur footprints are surprisingly rare in Wyoming compared to other western states with contemporary deposits. This might be due to the local ancient environments not being well suited for track preservation or merely because scientists have not yet looked in the right places.〔 During the early part of the Cenozoic, Wyoming was home to dense forests. Contemporary local vegetation would leave behind significant coal deposits. Massive lakes formed in the low lying areas between local mountains. One inhabitant of these lakes, ''Knightia eocaena'' is the state fossil. The Rocky Mountains were still being formed and the local geologic upheaval caused volcanic eruptions.〔 During the Paleocene, the Big Horn Basin was home to a unique mammal fauna.〔 During the Eocene Wyoming contained significant freshwater lakes. The blue-green algae ''Chlorellopsis'' grew in this lake. Its fossils are preserved in deposits left around the shores of these lakes. The Green River deposits contain the best preserved freshwater fish fossils in the world not far from Bridger. The seven foot tall flightless bird ''Diatryma'' roamed the land. Other land life of Eocene Wyoming include creodonts and a wide variety of insects that left their remains near Henry's Fork, not far from the boundary with neighboring Utah. The Bridger Basin was home to creatures like relatives of camels, carnivorans, elephants, horses, primates, rodents, ''Uintatherium'', and whales.〔 During the Quaternary, volcanic activity continued throughout much of the state and glaciers left significant deposits in the western half of the state.〔 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 Wyoming」の詳細全文を読む スポンサード リンク
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