Red Gulch Dinosaur Tracksite is an assemblage of fossil

dinosaur Dinosaurs are a diverse group of reptiles of the clade Dinosauria. They first appeared during the Triassic Geological period, period, between 243 and 233.23 million years ago (mya), although the exact origin and timing of the #Evolutio ...

footprints on public land near

Shell Shell may refer to: Architecture and design * Shell (structure), a thin structure ** Concrete shell, a thin shell of concrete, usually with no interior columns or exterior buttresses Science Biology * Seashell, a hard outer layer of a marine ani ...

, in

Big Horn County, Wyoming Big Horn County is a county in the U.S. state of Wyoming. As of the 2020 United States census, the population was 11,521. The county seat is Basin. Its north boundary abuts the south boundary of Montana. History Big Horn County was created ...

. They were discovered in 1997 by Erik P. Kvale, a research geologist from the

Indiana Geological Survey Created in 1837, the Indiana Geological and Water Survey (IGWS) is an official agency of the U.S. state of Indiana charged with geological research and the dissemination of information about the state's energy, mineral and water resources. In 20 ...

. The site is managed by the

Bureau of Land Management The Bureau of Land Management (BLM) is an agency within the United States Department of the Interior responsible for administering federal lands, U.S. federal lands. Headquartered in Washington, D.C., the BLM oversees more than of land, or one ...

as part of the Red Gulch/Alkali National Back Country Byway and is open to the public.

Fossils

The fossilized tracks are believed to have been made during the

Middle Jurassic The Middle Jurassic is the second Epoch (geology), epoch of the Jurassic Period (geology), Period. It lasted from about 174.1 to 161.5 million years ago. Fossils of land-dwelling animals, such as dinosaurs, from the Middle Jurassic are relativel ...

Period, 160–180 million years b.p., on what was then a shore of the

Sundance Sea The Sundance Sea was an epeiric sea that existed in North America during the mid-to-late Jurassic Period of the Mesozoic Era. It was an arm of what is now the Arctic Ocean, and extended through what is now western Canada into the central western ...

Theropod Theropoda (; from ancient Greek , (''therion'') "wild beast"; , (''pous, podos'') "foot"">wiktionary:ποδός"> (''pous, podos'') "foot" is one of the three major groups (clades) of dinosaurs, alongside Ornithischia and Sauropodom ...

tracks are thought to be among those discovered, but evidence suggests that the tracks were made by a large, diverse group of dinosaurs. Due to a rarity of Middle Jurassic theropods, the species that made the tracks is currently unknown. The majority of the footprints are in the area dubbed "the ballroom". Besides the trackways, a variety of fossils can be found, including

belemnite Belemnitida (or belemnites) is an extinct order (biology), order of squid-like cephalopods that existed from the Late Triassic to Late Cretaceous (And possibly the Eocene). Unlike squid, belemnites had an internal skeleton that made up the cone ...

crinoid Crinoids are marine invertebrates that make up the class Crinoidea. Crinoids that remain attached to the sea floor by a stalk in their adult form are commonly called sea lilies, while the unstalked forms, called feather stars or comatulids, are ...

s, and shrimp burrows.

Geology

The tracksite is in a

limestone Limestone is a type of carbonate rock, carbonate sedimentary rock which is the main source of the material Lime (material), lime. It is composed mostly of the minerals calcite and aragonite, which are different Polymorphism (materials science) ...

layer in the lower part of the

Sundance Formation 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 ...

. Its discovery was somewhat surprising, since the Sundance was historically considered to be marine in nature. Indeed, the layer just above the tracksite contains abundant marine fossils including numerous ''

Gryphaea ''Gryphaea'', one of the genera known as devil's toenails, is a genus of extinct oysters, marine bivalve mollusks in the family Gryphaeidae. These fossils range from the Triassic period to the middle Paleogene period, but are mostly restricte ...

nebrascensis'', indicating that later in the Jurassic it was once again submerged.

References

External links

BLM Wyoming.gov: official Red Gulch Dinosaur Tracksite website

{{authority control Fossil trackways in the United States Fossil parks in the United States Jurassic geology of Wyoming Jurassic paleontological sites of North America Paleontology in Wyoming 1997 in paleontology Protected areas of Big Horn County, Wyoming Bureau of Land Management areas in Wyoming

Fossils

Geology

See also

References

External links