Purgatoire River track site

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One of the dinosaur trackways at the Purgatoire River track site. PurgatoireTrackwayCO.jpg
One of the dinosaur trackways at the Purgatoire River track site.
Theropod footprint at the Purgatoire River dinosaur track site, Picket Wire Canyonlands, Colorado, U.S.A. AllosaurusFootprintCO.jpg
Theropod footprint at the Purgatoire River dinosaur track site, Picket Wire Canyonlands, Colorado, U.S.A.
Interp Panel 1 Largest Dinosaur Tracksite in North America.jpg
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Interp Panel 2 Life at Dinosaur Lake.jpg
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Interp Panel 3 Aerial Image of Purgatoire Tracksite.jpg
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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.

Contents

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]

Geology

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]

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<span class="mw-page-title-main">Morrison Formation</span> Rock formation in the western United States

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.

<span class="mw-page-title-main">Uncompahgre National Forest</span> National Forest in western Colorado, United States

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.

<span class="mw-page-title-main">Comanche National Grassland</span> Protected area in southeast Colorado

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.

<i>Marshosaurus</i> Extinct genus of dinosaurs

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.

<span class="mw-page-title-main">Kayenta Formation</span> Jurassic sandstone formation of the southwestern United States

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.

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<span class="mw-page-title-main">Purgatoire River</span> River

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.

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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.

<span class="mw-page-title-main">Aztec Sandstone</span> Early Jurassic geological formation in the Mojave Desert, United States

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.

<span class="mw-page-title-main">Martin Lockley</span> Welsh palaeontologist (1950–2023)

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.

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