The Purgatoire River track site, also called the Picketwire Canyonlands tracksite, is one of the largest dinosaur tracksites in North America. [1] 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.
In 2014 researchers published information about the discovery of a new area containing 90 trackways. These paralleled existing trackways of sauropods. This observation confirmed the major finding of these studies, that the sauropods displayed gregarious behavior. [2]
The tracksite is far from paved roads, but accessible to the public by hiking on foot, by mountain bike, or by horseback. Motorized vehicle access is restricted to tours conducted by the US Forest Service. [3]
In 2001, the first discoveries in the Picketwire Canyonlands area were made of related fossil dinosaur bones. Fieldwork has continued each year on recovery of the massive bones of a sauropod (brontosaur) skeleton. The project has been supported by volunteers and the Sternberg Museum of Natural History of western Kansas. [4] Continued exploration of fossils in the canyonlands has revealed tetrapods. This finding had major implications for understanding of geology in the area. As a result, researchers in 2012 proposed a "major revision of lower Mesozoic stratigraphy in the Picket Wire Canyonlands" and a "critical reappraisal of understanding of the correlation of Triassic strata from Wyoming, through and under the Denver Basin, to the High Plains of Oklahoma and New Mexico." [5]
The more than 100 trackways, made up of more than 1500 individual footprints, were made by both biped and quadruped dinosaurs. The tracks occur in limestone of the Jurassic Morrison Formation. The site formed along the shore of a large freshwater lake at the time the tracks were made. A previously unmapped region was discovered in 2012, where removal of alluvium revealed 90 new trackways, showing parallel prints. [2]
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.
Uncompahgre National Forest is a U.S. National Forest covering 955,229 acres in parts of Montrose, Mesa, San Miguel, Ouray, Gunnison, Hinsdale, San Juan, and Delta Counties in western Colorado. Its headquarters are in Delta County, in the city of Delta. It borders the San Juan National Forest to the south.
Comanche National Grassland is a National Grassland located in southeastern Colorado, United States. It is the sister grassland of Cimarron National Grassland and contains both prairie grasslands and canyons. It is separated into two sections, each operated by a local ranger district, one of which is in Springfield and the other of which is in La Junta. The grassland is administered by the Forest Service together with the Pike and San Isabel National Forests, and the Cimarron National Grassland, from common headquarters located in Pueblo, Colorado.
Marshosaurus is a genus of medium-sized carnivorous theropod dinosaur, belonging to the family Piatnitzkysauridae, from the Late Jurassic Morrison Formation of Utah and possibly Colorado.
The Kayenta Formation is a geological formation in the Glen Canyon Group that is spread across the Colorado Plateau province of the United States, including northern Arizona, northwest Colorado, Nevada, and Utah. Traditionally has been suggested as Sinemurian-Pliensbachian, but more recent dating of detrital zircons has yielded a depositional age of 183.7 ± 2.7 Ma, thus a Pliensbachian-Toarcian age is more likely. A previous depth work recovered a solid "Carixian" age from measurements done in the Tenney Canyon. More recent works have provided varied datations for the layers, with samples from Colorado and Arizona suggesting 197.0±1.5-195.2±5.5 Ma, while the topmost section is likely Toarcian or close in age, maybe even recovering terrestrial deposits coeval with the Toarcian Oceanic Anoxic Event. This last age asignation also correlated the Toarcian Vulcanism on the west Cordilleran Magmatic Arc, as the number of grains from this event correlate with the silt content in the sandstones of the upper layers.
A fossil track or ichnite is a fossilized footprint. This is a type of trace fossil. A fossil trackway is a sequence of fossil tracks left by a single organism. Over the years, many ichnites have been found, around the world, giving important clues about the behaviour of the animals that made them. For instance, multiple ichnites of a single species, close together, suggest 'herd' or 'pack' behaviour of that species.
The Ziliujing Formation is a geological formation in China, It is Early Jurassic in age. It is part of the stratigraphy of the Sichuan Basin. The dinosaur Gongxianosaurus and indeterminate theropod material are known from the Dongyuemiao Member of the formation, as well as dinosaur footprints, Zizhongosaurus and indeterminate prosauropods from the Da'anzhai Member. The basal sauropod Sanpasaurus is known from the Maanshan Member. An unnamed stegosaur and the pliosauroid plesiosaur Sinopliosaurus are also known from this formation but they were found an indeterminate member. An unnamed teleosaurid known from a complete skull has also been found in the formation, pending a formal description. The deposition environment during the Da'anzhai Member in the lower Toarcian is thought to have been that of a giant freshwater lake encompassing the whole of the Sichuan basin, around 3 times larger than Lake Superior, coeval with the Toarcian Oceanic Anoxic Event around 183 Ma.
The Purgatoire River, also known as the Purgatory and Picketwire River, is in southeastern Colorado, United States. The river originates in the high mountains of the Culebra Range. Several tributaries merge near Weston in Las Animas County and the river flows east-northeastward 196 miles (315 km) to a confluence with the Arkansas River near Las Animas in Bent County, Colorado. The Purgatoire River drains an area of 3,449 square miles (8,930 km2), mostly in Colorado but a small percentage of the watershed is in New Mexico. The Purgatoire River watershed is lightly populated. Population has been declining since 1920 as former coal mining and agricultural communities have become ghost towns.
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.
The Aztec Sandstone is an Early Jurassic geological formation of primarily eolian sand from which fossil pterosaur tracks have been recovered. The formation is exposed in the Mojave Desert of Arizona, California and Nevada. Aztec Sandstone is named after the Aztec Tank, a lake in the Spring Mountain region of Nevada.
Martin G. Lockley was 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 had been a professor at the University of Colorado at Denver, (UCD) and was later Professor Emeritus. He is best known for his work on fossil footprints and was the former director of the Dinosaur Tracks Museum at UCD. He was 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 Calcários Micríticos da Serra de Aire is a Bathonian geologic formation in Portugal. Fossil sauropod tracks have been reported from the formation.
Parabrontopodus is an ichnogenus of dinosaur footprint, that was initially described by Lockley et al. in 1994, and was assigned to Sauropoda by Lockley in 2002 and in 2004 by Niedzwiedzki and Pienkowski. Various species through their footprints that are characterized by the association of two impressions left by hand and foot. The acquisition of a specific family is complex, but now in most cases, they have been considered diplodocoids and similar animals. The reason is that their traces left are large, but in proportion to the size, from animals, seem very light because the depth of imprint is low.
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 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.
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.
The Bell Ranch Formation is a Late Jurassic (Kimmeridgian) geologic formation in eastern and northeastern New Mexico and the western Oklahoma panhandle. Fossil theropod tracks have been reported from the formation.
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.