The Tensleep Sandstone is a

geological formation A geological formation, or simply formation, is a body of rock having a consistent set of physical characteristics (lithology) that distinguishes it from adjacent bodies of rock, and which occupies a particular position in the layers of rock expo ...

Pennsylvanian Pennsylvanian may refer to: * A person or thing from Pennsylvania * Pennsylvanian (geology) The Pennsylvanian ( , also known as Upper Carboniferous or Late Carboniferous) is, in the International Commission on Stratigraphy, ICS geologic timesca ...

to very early

Permian The Permian ( ) is a geologic period and stratigraphic system which spans 47 million years from the end of the Carboniferous Period million years ago (Mya), to the beginning of the Triassic Period 251.9 Mya. It is the last period of the Pale ...

age in Wyoming. The formation is composed of fine- to medium-grained sandstone, light gray and yellowish gray; generally slightly to moderately calcareous; some dolomite and sandy dolomite beds; mostly thick to massive sets of low-angle, wedge-planar crossbeds of dunes. Forms cliffs 61-91m (200-300 feet) thick.Maughan, E.K. 1972. Geologic map of the Wedding of the Waters Quadrangle, Hot Springs County, Wyoming. US Geological Survey Map GQ-1042

Trace fossils

In 1932

Edward Branson Edward B. Branson was an American geologist and paleontologist. He was a professor of geology at the University of Missouri. Overview of career Branson earned his doctorate at the University of Chicago and joined the Geology department at the U ...

and

Maurice Mehl Maurice Goldsmith Mehl (1887 - 1966) was an American paleontologist and professor in the Department of Geology at the University of Missouri. Life and career Mehl was born on December 25, 1887, to Frank and Rebecca Goldsmith Mehl. After gradu ...

reported the discovery of a fossil trackway in the formation. A new ichnospecies, '' Steganoposaurus belli'', was erected for these footprints. The tracks were probably made by a web-footed animal slightly less than three feet long. This creature was originally presumed to be an amphibian, but the toe prints it left behind were pointed like a reptile's rather than round like an amphibians. The actual trackmaker may have been similar to the genus ''

Hylonomus ''Hylonomus'' (; ''hylo-'' "forest" + ''nomos'' "dweller") is an extinct genus of reptile that lived 312 million years ago during the Late Carboniferous period. It is the earliest unquestionable reptile (''Westlothiana'' is older, but in fact i ...

''. The ichnogenus '' Tridentichnus'' are similar footprints preserved in the Supai Formation of

Arizona Arizona ( ; nv, Hoozdo Hahoodzo ; ood, Alĭ ṣonak ) is a U.S. state, state in the Southwestern United States. It is the list of U.S. states and territories by area, 6th largest and the list of U.S. states and territories by population, 14 ...

References

{{Reflist, 3, refs= "Western Traces in the 'Age of Amphibians'," Lockley and Hunt (1995); page 34. "Western Traces in the 'Age of Amphibians'," Lockley and Hunt (1995); pages 34-35. "Western Traces in the 'Age of Amphibians'," Lockley and Hunt (1995); page 35.

Bibliography

* Lockley, Martin and Hunt, Adrian. '' Dinosaur Tracks of Western North America''.

Columbia University Press Columbia University Press is a university press based in New York City, and affiliated with Columbia University. It is currently directed by Jennifer Crewe (2014–present) and publishes titles in the humanities and sciences, including the fi ...

. 1999. Geologic formations of Wyoming Carboniferous System of North America Pennsylvanian Series Cisuralian Series of North America Sandstone formations of the United States Ichnofossiliferous formations