Paleontology in Colorado refers to paleontological research occurring within or conducted by people from the U.S. state of Colorado. The geologic column of Colorado spans about one third of Earth's history. Fossils can be found almost everywhere in the state but are not evenly distributed among all the ages of the state's rocks.During the early Paleozoic, Colorado was covered by a warm shallow sea that would come to be home to creatures like brachiopods, conodonts, ostracoderms, sharks and trilobites. This sea withdrew from the state between the Silurian and early Devonian leaving a gap in the local rock record. It returned during the Carboniferous. Areas of the state not submerged were richly vegetated and inhabited by amphibians that left behind footprints that would later fossilize. During the Permian, the sea withdrew and alluvial fans and sand dunes spread across the state. Many trace fossils are known from these deposits.
The sea returned during the Triassic, while exposed areas were a richly vegetated coastal plain that was home to dinosaurs. Colorado was again submerged by a sea during the Cretaceous period that was home to plesiosaurs up to 70 feet long. During the early part of the Cenozoic era, rainforests grew in Colorado. Later, another rich flora and fauna would come to be preserved in the Florissant beds, where both rhinoceroses and uintatheres lived. More recently the state's modern prairies began to form and the state was home to creatures like bison, camels, horses, and mammoths. Local Native Americans have devised myths to explain local fossil bones and dinosaur footprints. By the late 19th century, local fossils had attracted the attention of formally trainer scientists. Major finds include the Late Jurassic dinosaurs of the Morrison Formation and the Cenozoic plants and mammals of the Florissant beds. The Jurassic plated dinosaur Stegosaurus armatus is the Colorado state fossil. Stegosaurus is also the state dinosaur of Colorado.
No Precambrian fossils are known from Colorado, so the state's fossil record does not begin until the Paleozoic.At the start of the Paleozoic, Colorado was located near the equator. The state was submerged under a warm shallow sea. At least part of Colorado was covered by shallow water during the Middle Ordovician. At the time, Colorado was home to invertebrates like articulated brachiopods, conodonts, gastropods, ostracods, pelecypods, sponges, trilobites, and worms (known from trace fossils). Contemporary vertebrates included armored jawless fish called ostracoderms. Sometime between the Silurian and early Devonian the sea withdrew from the state. While the sea was gone local sediments were eroded away rather than deposited. During the Carboniferous the absent sea returned, although some areas of the state remained dry land. Brachiopods, crinoids, sharks, and trilobites inhabited the sea. A rich variety of plants grew in Colorado's terrestrial environments. Examples include Calamites , conifers, and lycopods. Mountain ranges were being raised in the western part of the state by geologic forces. During the Carboniferous, footprints were laid down in Colorado by early tetrapods that would later fossilize. That being said, Colorado is not generally a good source of Carboniferous aged fossils. Western Colorado had a series of alluvial fans during the Permian when the Cutler Group was being deposited. Preserved in these sediments are tracks referred to the ichnospecies Limnopus cutlerensis , which may have been left by a temnospodyl amphibian. During the Permian the sea withdrew once more from the state. In its place were fields of sand dunes. Tracks left by ancient insects and reptiles were preserved in these dune deposits. Also like the Carboniferous, despite the presence of contemporary trace fossils, the fossil record of Permian life in Colorado is relatively poor compared to states like Kansas and Texas.
Seawater returned to Colorado during the ensuing Triassic period, although it left significant areas of the state uncovered.These terrestrial areas included coastal floodplains vegetated by conifers and inhabited by creatures like amphibians and dinosaurs. The Late Triassic also saw the formation of many footprints that would later fossilize. These are preserved in the sediments of the Chinle Formation of the northwestern part of the state. A chicken to turkey sized theropod dinosaur left behind footprints of the ichnogenus Agialopous . These tracks contain large number of the ichnogenus Rhynchosauroides , which resembles lizard footprints. The Chinle of Colorado also bears the greatest known abundance of the ichnogenus Gwynnedichnium . Both Triassic amphibians and reptiles left behind footprints near what is now the Fall Creek Post Office.
During the Late Jurassic deposition of the sediments now known as the Morrison Formation, both sauropods and theropods left behind footprints.Only two large tracksites of fossil footprints are known from the Morrison Formation and both of them are located in Colorado. A tracksite called Rancho del Rio preserves both sauropod and theropod tracks. The Rancho del Rio site is located along the Colorado River in central Colorado. The other large tracksite is the Purgatoire Valley tracksite of the eponymous Purgatoire River in southeastern Colorado. The Purgatoire Valley tracksite is 400 meters at its widest and contains four track-bearing strata. One of the four track bearing strata bears more than 1,300 individual prints. A series of five parallel trackways left by young sauropods provides important evidence for dinosaur social behavior. The trackways of young sauropods found at the Purgatoire Valley site fill important gaps in the local body fossil record, as the vast majority of sauropods skeletal remains in the Morrison come from grown individuals.
Much of Colorado was covered by an expanding sea during the ensuing Cretaceous period.This sea is known as the Western Interior Seaway. Algae, fish, molluscs, and marine reptiles inhabited its waters. The mosasaur Platecarpus was one such marine reptile. When the Graneros Shale was being deposited in Colorado, the plesiosaur Thalassomedon lived in the state. This was a truly huge plesiosaur that could exceed 45 feet in length. Beyond the shores of this sea were forests and swamps where early flowering plants grew. Later in the Cretaceous, the sea withdrew. Dinosaurs were still present, but the vegetation had undergone significant changes. The forests were now made of broadleafed trees and palms. At this point the local Rocky Mountains began to rise. During the Cretaceous cephalopods with coiled shells and clams were preserved at Monument Creek. Fish were present in Coloradan waters and left behind scales that would later fossilize. On land the flora also left behind leaves that would later fossilize. The sediments of the Benton Formation preserved both invertebrates and marine reptiles. The bivalve Ostrea congesta was preserved in the Colorado Niobrara Formation. The Niobrara's vertebrate life included sharks, which left behind fossil teeth. Colorado was home to bivalves and straight shelled cephalopods when the Pierre shale was being deposited. The Pierre shale are mound-shaped bioherms up to 15 inches in diameter. A sixty to seventy foot plesiosaur was preserved in what is now Baca County, which is in the southeastern region of the state. Marine mollusks were preserved in the Fox Hills Formation. Oysters and other mollusks were preserved in the sediments now composing the Dakota Formation. Aspects of the Coloradan flora were also preserved from this time. The most common plant fossils of the Dakota are the leaves of deciduous trees. Other contemporary plants included ferns and palms.
The uplift of the Rocky Mountains persisted into the early part of the Cenozoic era. They were surrounded by rainforests at this point in prehistory. Areas in the state with lower elevation became the sites of vast lakes. Fish, insects, and leaves would end up entombed in sediments deposited by these lakes.After the start of the Cenozoic, early Paleocene turtles left behind fossils near modern Golden. The Coloradan flora of the ensuing Eocene epoch left behind plant fossils like ferns, palm leaves, and petrified wood. Animal life of northwestern Colorado during the Eocene included the primitive horse Eohippus , early titanotheres, and uintatheres. A rich flora grew in Colorado during the Oligocene. At least 150 different kinds of plants from this epoch are preserved in what is now the Florissant beds of Colorado. Among the members of this flora were sequoia trees with trunks up to 17 and a half feet in diameter. More than a thousand different kinds of insect have been documented among the same beds. Beetles were among the Florissant insects. A diverse mammalian fauna inhabited this ancient forest. Members included animals resembling giant pigs, rhinoceroses, and titanotheres. During the Pliocene, Colorado was home to creatures like rhinoceroses and giant pig-like animals. The state's modern prairies formed during the Quaternary. Colorado was shaken by volcanic eruptions. The state's climate gradually cooled as the Cenozoic proceeded. The rainforests gave way to sequoia forests and grasslands. Pleistocene Colorado had a diverse mammal fauna. Among them were Archidiskodon , a relative of modern elephants. Bison, camels, horses, and mammoths also inhabited the state at this time.
Not far from Grand Junction is a tall cottonwood tree called the Ute Council Tree. Close by is an obvious dinosaur track site. The Ute had a myth regarding these tracks that justified the tree as a significant meeting place, although the contents of the tale are now lost.Oglala Lakota historian Johnson Holy Rock has described an old story about a Lakota hunting party traveling through northeastern Colorado who were caught during an exceptionally violent thunderstorm while camping. They thought the violence of the storm was due to the Thunder Birds being angry and trying to kill something with their lightning. When morning came, the Lakota hunters went down onto the plain where the storm was most intense. There they found the carcass of an animal with an unusual long nose who was "so strange that they wondered how it managed to eat." This story may be based on the region's abundant fossils. Candidates for the unusual remains found after the storm include brontotheres, entelodonts, or proboscidean remains. Johnson Holy Rock, who told the story, was inclined to think of the animal as a proboscidean or giant tapir.
Around March 1877 a man named Oramel Lucas discovered sauropod bones in a valley called Garden Park located a few miles north of Canon City. He wrote to Edward Drinker Cope and O. C. Marsh, the famous rival paleontologists of the bone wars to alert them about his discovery. Although Marsh never responded, Cope did, and Oramel Lucas and his brother Ira began digging up local fossils and sending them to Cope. These turned out to be the remains of a new species. By August of the same year, Cope had formally named the animal excavated by the Lucas brothers Camarasaurus supremus . This species may have been the most massive known in the entire Morrison Formation, with estimated putting its body weight at more than 100,000 lbs. Later, a crew working on behalf of O. C. Marsh under Mudge and Williston started a quarry nearby. They made several important finds like the new species Allosaurus fragilis and Diplodocus longus . Following the initial excavations in the quarry field work stopped until 1883. That year brothers Marshall and Henry Felch reopened excavations there, again on behalf of O. C. Marsh. They worked for five year collecting many dinosaurs already known from the formation, but also the new species Ceratosaurus nasicornis .
In 1890 paleontologist Charles D. Walcott found broken pieces of the bony plates embedded in the skin of Middle Ordovician jawless fish known as ostracoderms. These fossils were the oldest known vertebrate remains in the world at the time. The rocks preserving the fossils were gray and reddish sandstone deposited by shallow water. Other fossils found alongside the ostracoderms lived articulated brachiopods, conodonts, gastropods, ostracods, pelecypods, sponges, trilobites, and trace fossils left by worms.
After the Felch brothers ended their field work, the so-called Marsh-Felch quarry lay unworked for twelve years. However, in 1900 William Utterback began fieldwork in the area under John Bell Hatcher for the Carnegie Museum of Natural History. In the two ensuing years of field work Utterback found many skeletons of previously known dinosaurs, but also the new genus Haplocanthosaurus . This was the smallest known sauropod species of the Morrison Formation.Around 1920 major fossil finds occurred in Oligocene deposits Colorado shares with South Dakota. Dozens of articulated skeletons and skulls were uncovered. Among them were animals resembling giant pigs, rhinoceroses, and titanotheres. One notable rhinoceros discovery had occurred in Weld County. In 1925 small duckbilled dinosaurs were discovered in eastern Colorado. Later, in 1955, the American Museum of Natural History uncovered a stone block in south-central Colorado preserving several Eocene Eohippus skeletons.
In 1960 Malcolm McKenna discovered two early Paleocene turtles on behalf of the American Museum of Natural History on South Table Mountain. The following year, curator of the University of Colorado Museum at Boulder discovered even more turtles of that age at the same place.In the summer of 1961 a major discovery happened south of Denver in Douglas County, at a site known as Lamb Spring. Charles Lamb, the owner of a tract of land used for cattle grazing, was dredging out the bottom of a watering hole for the cattle. A great abundance of bones were discovered under the thin layer of mud at the bottom of the watering hole. The owners alerted paleontologists at Denver about the find. The researchers at Denver passed on word of the find to the Smithsonian Institution of Washington D.C. In response, the National Science Foundation funded an expedition coordinated by the Smithsonian Institution to the wateringhole. The lowest bones in the deposit were left by Columbian mammoths. Higher in the deposit the excavators uncovered bison, camels, and horses. By the end of the summer, 13 gigantic cases containing a total of 341 fossil bones were shipped to the National Museum in Washington D.C. The site is now managed and protected as Lamb Spring Archaeological Preserve. In the spring of 1963, road work in Limon County near the town of Limon uncovered a mammoth tooth and tusk.
In 1965, the Florissant fossil beds were proposed as a potential federal preserve.Peter Robinson studied the Miocene fossil vertebrates of Middle Park during the mid 1960s. These fossils were discovered a short distance northwest of Denver. By 1964 he had discovered the skull of a relatively large camel. Another notable discovery during his research program was the seventh known microfauna site in the park. More recently, in 1982, the Jurassic plated dinosaur Stegosaurus armatus was designated the Colorado state fossil. Stegosaurus was also designated the Colorado state dinosaur that same year.
Elaine Anderson was born in Salida on January 8, 1936.Anderson would come to be known primarily for her book, The Pleistocene Mammals of North America and her research on Ice Age carnivores.
Myra Keen was born in Colorado Springs in 1905.She would go on to become one of the world's foremost paleomalacologists.
Elaine Anderson died in Denver on March 26, 2002 at age 66.
Malcolm McKenna died in Boulder on March 3, 2008.McKenna was best known for publishing a comprehensive classification of mammals.
Charles Repenning died in Lakewood on January 5, 2005.Repenning is known for research into fossil desmostylians and shrews.
The Morrison Formation is a distinctive sequence of Upper Jurassic sedimentary rock found in the western United States which has been the most fertile source of dinosaur fossils in North America. It is composed of mudstone, sandstone, siltstone, and limestone and is light gray, greenish gray, or red. Most of the fossils occur in the green siltstone beds and lower sandstones, relics of the rivers and floodplains of the Jurassic period.
The Sundance Formation is a western North American sequence of Middle Jurassic to Upper Jurassic age Dating from the Bathonian to the Oxfordian, around 168-157 Ma, It is up to 100 metres thick and consists of marine shale, sandy shale, sandstone, and limestone deposited in the Sundance Sea, an inland sea that covered large parts of western North America during the Middle and early Late Jurassic.
Dinosaur Ridge is a segment of the Dakota Hogback in the Morrison Fossil Area National Natural Landmark located in Jefferson County, Colorado, near the town of Morrison and just west of Denver.
The Uhangri Formation, located at the Uhangri Dinosaur Fossil Site, is a geological formation from which fossil pterosaur tracks have been recovered near Haenam-eup, Jeollanam-do, South Korea.
Martin G. Lockley is a Welsh palaeontologist. He was educated in the United Kingdom where he obtained degrees and post-doctoral experience in Geology in the 1970s. Since 1980 he has been a professor at the University of Colorado at Denver, (UCD) and is currently a Professor Emeritus. He is best known for work on fossil footprints and was former director of the Dinosaur Tracks Museum at UCD. He is an Associate Curator at the University of Colorado Museum of Natural History and Research Associate at the Denver Museum of Nature and Science. During his years at UCD he earned a BA in 2007 in Spanish with a minor in Religious Studies, became a member of the Scientific and Medical Network and taught and published on the evolution of consciousness.
The Purgatoire River track site, also called the Picketwire Canyonlands tracksite, is one of the largest dinosaur tracksites in North America. The site is located on public land of the Comanche National Grassland, along the Purgatoire ("Picketwire") River south of La Junta in Otero County, Colorado.
Paleontology in Maryland refers to paleontological research occurring within or conducted by people from the U.S. state of Maryland. The invertebrate fossils of Maryland are similar to those of neighboring Delaware. For most of the early Paleozoic era, Maryland was covered by a shallow sea, although it was above sea level for portions of the Ordovician and Devonian. The ancient marine life of Maryland included brachiopods and bryozoans while horsetails and scale trees grew on land. By the end of the era, the sea had left the state completely. In the early Mesozoic, Pangaea was splitting up. The same geologic forces that divided the supercontinent formed massive lakes. Dinosaur footprints were preserved along their shores. During the Cretaceous, the state was home to dinosaurs. During the early part of the Cenozoic era, the state was alternatingly submerged by sea water or exposed. During the Ice Age, mastodons lived in the state.
Paleontology in Arkansas refers to paleontological research occurring within or conducted by people from the U.S. state of Arkansas. The fossil record of Arkansas spans from the Ordovician to the Eocene. Nearly all of the state's fossils have come from ancient invertebrate life. During the early Paleozoic, much of Arkansas was covered by seawater. This sea would come to be home to creatures including Archimedes, brachiopods, and conodonts. This sea would begin its withdrawal during the Carboniferous, and by the Permian the entire state was dry land. Terrestrial conditions continued into the Triassic, but during the Jurassic, another sea encroached into the state's southern half. During the Cretaceous the state was still covered by seawater and home to marine invertebrates such as Belemnitella. On land the state was home to long necked sauropod dinosaurs, who left behind footprints and ostrich dinosaurs such as Arkansaurus.
Paleontology in Nebraska refers to paleontological research occurring within or conducted by people from the U.S. state of Nebraska. Nebraska is world-famous as a source of fossils. During the early Paleozoic, Nebraska was covered by a shallow sea that was probably home to creatures like brachiopods, corals, and trilobites. During the Carboniferous, a swampy system of river deltas expanded westward across the state. During the Permian period, the state continued to be mostly dry land. The Triassic and Jurassic are missing from the local rock record, but evidence suggests that during the Cretaceous the state was covered by the Western Interior Seaway, where ammonites, fish, sea turtles, and plesiosaurs swam. The coasts of this sea were home to flowers and dinosaurs. During the early Cenozoic, the sea withdrew and the state was home to mammals like camels and rhinoceros. Ice Age Nebraska was subject to glacial activity and home to creatures like the giant bear Arctodus, horses, mammoths, mastodon, shovel-tusked proboscideans, and Saber-toothed cats. Local Native Americans devised mythical explanations for fossils like attributing them to water monsters killed by their enemies, the thunderbirds. After formally trained scientists began investigating local fossils, major finds like the Agate Springs mammal bone beds occurred. The Pleistocene mammoths Mammuthus primigenius, Mammuthus columbi, and Mammuthus imperator are the Nebraska state fossils.
Paleontology in Kansas refers to paleontological research occurring within or conducted by people from the U.S. state of Kansas. Kansas has been the source of some of the most spectacular fossil discoveries in US history. The fossil record of Kansas spans from the Cambrian to the Pleistocene. From the Cambrian to the Devonian, Kansas was covered by a shallow sea. During the ensuing Carboniferous the local sea level began to rise and fall. When sea levels were low the state was home to richly vegetated deltaic swamps where early amphibians and reptiles lived. Seas expanded across most of the state again during the Permian, but on land the state was home to thousands of different insect species. The popular pterosaur Pteranodon is best known from this state. During the early part of the Cenozoic era Kansas became a savannah environment. Later, during the Ice Age, glaciers briefly entered the state, which was home to camels, mammoths, mastodons, and saber-teeth. Local fossils may have inspired Native Americans to regard some local hills as the homes of sacred spirit animals. Major scientific discoveries in Kansas included the pterosaur Pteranodon and a fossil of the fish Xiphactinus that died in the act of swallowing another fish.
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.
Paleontology in Texas refers to paleontological research occurring within or conducted by people from the U.S. state of Texas. Author Marian Murray has remarked that "Texas is as big for fossils as it is for everything else." Some of the most important fossil finds in United States history have come from Texas. Fossils can be found throughout most of the state. The fossil record of Texas spans almost the entire geologic column from Precambrian to Pleistocene. Shark teeth are probably the state's most common fossil. During the early Paleozoic era Texas was covered by a sea that would later be home to creatures like brachiopods, cephalopods, graptolites, and trilobites. Little is known about the state's Devonian and early Carboniferous life. However, evidence indicates that during the late Carboniferous the state was home to marine life, land plants and early reptiles. During the Permian, the seas largely shrank away, but nevertheless coral reefs formed in the state. The rest of Texas was a coastal plain inhabited by early relatives of mammals like Dimetrodon and Edaphosaurus. During the Triassic, a great river system formed in the state that was inhabited by crocodile-like phytosaurs. Little is known about Jurassic Texas, but there are fossil aquatic invertebrates of this age like ammonites in the state. During the Early Cretaceous local large sauropods and theropods left a great abundance of footprints. Later in the Cretaceous, the state was covered by the Western Interior Seaway and home to creatures like mosasaurs, plesiosaurs, and few icthyosaurs. Early Cenozoic Texas still contained areas covered in seawater where invertebrates and sharks lived. On land the state would come to be home to creatures like glyptodonts, mammoths, mastodons, saber-toothed cats, giant ground sloths, titanotheres, uintatheres, and dire wolves. Archaeological evidence suggests that local Native Americans knew about local fossils. Formally trained scientists were already investigating the state's fossils by the late 1800s. In 1938, a major dinosaur footprint find occurred near Glen Rose. Pleurocoelus was the Texas state dinosaur from 1997 to 2009, when it was replaced by Paluxysaurus jonesi after the Texan fossils once referred to the former species were reclassified to a new genus.
Paleontology in Montana refers to paleontological research occurring within or conducted by people from the U.S. state of Montana. The fossil record in Montana stretches all the way back to the Precambrian. During the Late Precambrian, western Montana was covered by a warm, shallow sea where local bacteria formed stromatolites and bottom-dwelling marine life left tracks on the sediment that would later fossilize. This sea remained in place during the early Paleozoic, although withdrew during the Silurian and Early Devonian, leaving a gap in the local rock record until its return. This sea was home to creatures including brachiopods, conodonts, crinoids, fish, and trilobites. During the Carboniferous the state was home to an unusual cartilaginous fish fauna. Later in the Paleozoic the sea began to withdraw, but with a brief return during the Permian.
Paleontology in Wyoming includes research into the prehistoric life of the U.S. state of Wyoming as well as investigations conducted by Wyomingite researchers and institutions into ancient life occurring elsewhere. The fossil record of the US state of Wyoming spans from the Precambrian to recent deposits. Many fossil sites are spread throughout the state. Wyoming is such a spectacular source of fossils that author Marian Murray noted in 1974 that "[e]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.
Paleontology in New Mexico refers to paleontological research occurring within or conducted by people from the U.S. state of New Mexico. The fossil record of New Mexico is exceptionally complete and spans almost the entire stratigraphic column. More than 3,300 different kinds of fossil organisms have been found in the state. Of these more than 700 of these were new to science and more than 100 of those were type species for new genera. During the early Paleozoic, southern and western New Mexico were submerged by a warm shallow sea that would come to be home to creatures including brachiopods, bryozoans, cartilaginous fishes, corals, graptolites, nautiloids, placoderms, and trilobites. During the Ordovician the state was home to algal reefs up to 300 feet high. During the Carboniferous, a richly vegetated island chain emerged from the local sea. Coral reefs formed in the state's seas while terrestrial regions of the state dried and were home to sand dunes. Local wildlife included Edaphosaurus, Ophiacodon, and Sphenacodon.
Paleontology in Utah refers to paleontological research occurring within or conducted by people from the U.S. state of Utah. Utah has a rich fossil record spanning almost all of the geologic column. During the Precambrian, the area of northeastern Utah now occupied by the Uinta Mountains was a shallow sea which was home to simple microorganisms. During the early Paleozoic Utah was still largely covered in seawater. The state's Paleozoic seas would come to be home to creatures like brachiopods, fishes, and trilobites. During the Permian the state came to resemble the Sahara desert and was home to amphibians, early relatives of mammals, and reptiles. During the Triassic about half of the state was covered by a sea home to creatures like the cephalopod Meekoceras, while dinosaurs whose footprints would later fossilize roamed the forests on land. Sand dunes returned during the Early Jurassic. During the Cretaceous the state was covered by the sea for the last time. The sea gave way to a complex of lakes during the Cenozoic era. Later, these lakes dissipated and the state was home to short-faced bears, bison, musk oxen, saber teeth, and giant ground sloths. Local Native Americans devised myths to explain fossils. Formally trained scientists have been aware of local fossils since at least the late 19th century. Major local finds include the bonebeds of Dinosaur National Monument. The Jurassic dinosaur Allosaurus fragilis is the Utah state fossil.
Paleontology in Arizona refers to paleontological research occurring within or conducted by people from the U.S. state of Arizona. The fossil record of Arizona dates to the Precambrian. During the Precambrian, Arizona was home to a shallow sea which was home to jellyfish and stromatolite-forming bacteria. This sea was still in place during the Cambrian period of the Paleozoic era and was home to brachiopods and trilobites, but it withdrew during the Ordovician and Silurian. The sea returned during the Devonian and was home to brachiopods, corals, and fishes. Sea levels began to rise and fall during the Carboniferous, leaving most of the state a richly vegetated coastal plain during the low spells. During the Permian, Arizona was richly vegetated but was submerged by seawater late in the period.
The history of paleontology in the United States refers to the developments and discoveries regarding fossils found within or by people from the United States of America. Local paleontology began informally with Native Americans, who have been familiar with fossils for thousands of years. They both told myths about them and applied them to practical purposes. African slaves also contributed their knowledge; the first reasonably accurate recorded identification of vertebrate fossils in the new world was made by slaves on a South Carolina plantation who recognized the elephant affinities of mammoth molars uncovered there in 1725. The first major fossil discovery to attract the attention of formally trained scientists were the Ice Age fossils of Kentucky's Big Bone Lick. These fossils were studied by eminent intellectuals like France's George Cuvier and local statesmen and frontiersman like Daniel Boone, Benjamin Franklin, William Henry Harrison, Thomas Jefferson, and George Washington. By the end of the 18th century possible dinosaur fossils had already been found.
The 20th century in ichnology refers to advances made between the years 1900 and 1999 in the scientific study of trace fossils, the preserved record of the behavior and physiological processes of ancient life forms, especially fossil footprints. Significant fossil trackway discoveries began almost immediately after the start of the 20th century with the 1900 discovery at Ipolytarnoc, Hungary of a wide variety of bird and mammal footprints left behind during the early Miocene. Not long after, fossil Iguanodon footprints were discovered in Sussex, England, a discovery that probably served as the inspiration for Sir Arthur Conan Doyle's The Lost World.
John Russell Foster is an American paleontologist. Foster has worked with dinosaur remains from the Late Jurassic of the Colorado Plateau and Rocky Mountains, as well as working on Cambrian age trilobite faunas in the southwest region of the American west. He named the crocodiliform trace fossil Hatcherichnus sanjuanensis in 1997 and identified the first known occurrence of the theropod trace fossil Hispanosauropus in North America in 2015.
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