Aztec Sandstone

The Aztec Sandstone is an Early Jurassic geological formation of primarily eolian sand from which fossil pterosaur tracks have been recovered.[4] The formation is exposed in the Mojave Desert of Arizona, California and Nevada.

Aztec Sandstone Stratigraphic range: Early Jurassic
Outcrop of the Aztec Sandstone at Red Rock Canyon National Conservation Area near Las Vegas, Nevada
Type	Sedimentary
Underlies	Willow Tank Formation[1]
Overlies	Chinle Formation
Area	Nevada,[2] Arizona, California[3]
Thickness	2,100 ft (640 m) in Goodsprings quadrangle[2] 2,500 ft (760 m) in Muddy Mountain area[1]
Lithology
Primary	Sandstone
Location
Coordinates	35.4°N 115.5°W
Approximate paleocoordinates	20.8°N 53.4°W
Region	Mojave Desert
Country	United States
Type section
Named by	D. F. Hewett[2]
Year defined	1931
Aztec Sandstone (the United States) Aztec Sandstone (California)

Description

The Aztec Sandstone is made up of two units. The lower resistant sandstone unit (100 metres (330 ft) thick) is tan to off-white in outcrops but pinkish in fresh exposures. Crosbedded lenses can easily be observed. Frosted and pitted quartz grains well-cemented by silica are described by Evans in 1958 and 1971. The upper and less resistant unit (200m thick) consists of alternating white quartz arenites and red to brown silty sands.[5]

Vertebrate paleofauna

The formation has provided the following ichnofossils attributed to vertebrates:[4]

Ichnofossils of the Aztec Sandstone
Genus	Species	Location	Member	Abundance	Notes	Images
Anchisauripus[6]					Reclassified as Grallator
Brasilichnium
Grallator[7]
Navahopus
Octopodichnus
Pteraichnus[8]
Skolithos

Color key Taxon Reclassified taxon Taxon falsely reported as present Dubious taxon or junior synonym Ichnotaxon Ootaxon Morphotaxon		Notes Uncertain or tentative taxa are in small text; crossed out taxa are discredited.

See also

• List of fossil sites
• List of fossiliferous stratigraphic units in California
• List of fossiliferous stratigraphic units in Nevada

References

1. Longwell, C.R., 1949, Structure of the northern Muddy Mountain area, Nevada: Geological Society of America Bulletin, v. 60, no. 5, p. 923-967.
2. Hewett, D.F., 1931, Geology and ore deposits of the Goodsprings quadrangle, Nevada: U.S. Geological Survey Professional Paper, 162, 172 p., (incl. geologic map, scale 1:62,500)
3. Jennings, C.W., 1961, Geologic map of California; Kingman sheet: California Division of Mines and Geology, scale 1:250,000
4. Aztec Sandstone at Fossilworks.org
5. Mescal Range at Fossilworks.org
6. Listed as "cf. Anchisauripus" in "Appendix: Summary of the Mesozoic Reptilian Fossils of California," Hilton (2003) p. 265
7. Listed as "cf. Grallator" in "Appendix: Summary of the Mesozoic Reptilian Fossils of California," in Hilton (2003) p. 265
8. Lockley, et al. (2008)

Bibliography

• J. W. Bonde, D. J. Varricchio, F. D. Jackson, D. B. Loope, and A. M. Shirk. 2008. Dinosaurs and dunes! Sedimentology and paleontology of the Mesozoic in the Valley of Fire State Park. In E. M. Duebendorfer & E. I. Smith (ed.), Field Guide to Plutons, Volcanoes, Faults, Reefs, Dinosaurs, and Possible Glaciation in Selected Areas of Arizona, California, and Nevada: Geological Society of America Field Guide 11:249-262
• Lockley, M.; Harris, J.D.; and Mitchell, L. 2008. "A global overview of pterosaur ichnology: tracksite distribution in space and time." Zitteliana. B28. p. 187-198. ISSN 1612-4138.
• Porter, M.L., 2006. Sedimentology of an ancient erg margin: the Lower Jurassic Aztec Sandstone, southern Nevada and southern California. Sedimentology 34:661-680.
• Hilton, Richard P. 2003. Dinosaurs and Other Mesozoic Reptiles of California. Berkeley: University of California Press. 318 pp.

Further reading

• R. E. Reynolds. 1986. California trackways from the Lower Jurassic Aztec Sandstone. In D. D. Gillette (ed.), First International Symposium on Dinosaur Tracks and Traces. Abstracts with Program 24