Fossil Bones In The Coso Range, California

Visit the Coso Range Wilderness in Inyo County, California, west of Death Valley National Park at the southern end of California's Owens Valley, where vertebrate fossils some 4.8 to 3.0 million years old can be observed in the Pliocene-age Coso Formation: It's a paleontologically significant place that yields many species of mammals, including the remains of Equus simplicidens, the Hagerman Horse, named for its spectacular occurrences at Hagerman Fossil Beds National Monument in Idaho; Equus simplicidens is considered the earliest known member of the genus Equus, which includes the modern horse and all other equids.

Please note that fossil collecting is not allowed within the designated Coso Range Wilderness, except by special permit issued by the Bureau of Land Management--a permit given only to trained scientists with a degree who represent either an accredited university or a museum.

Also, as a special archaeological attraction, the Coso Range contains the largest concentration of prehistoric petroglyph rock art drawings in North America; tours to the world-famous petroglyph sites in Petroglyph Canyon must be arranged through the Maturango Museum in Ridgecrest, California. See the Olancha And Coso Links page for Internet resources pertaining to the Coso Range rock art drawings.

And now for the obligatory words of caution. Endemic to the Mojave Desert of California, including the Las Vegas, Nevada, region by the way, is Valley Fever. This is a potentially serious illness called, scientifically, Coccidioidomycosis, or "coccy" for short; it's caused by the inhalation of an infectious airborne fungus whose spores lie dormant in the uncultivated, harsh alkaline soils of the Mojave Desert. The Coso Mountains lie near the northern known edges of Valley Fever prevalence within the Mojave Desert province. When an unsuspecting and susceptible individual breaths the spores into his or her lungs, the fungus springs to life, as it prefers the moist, dark recesses of the human lungs (cats, dogs, rodents and even snakes, among other vertebrates, are also susceptible to "coccy") to multiply and be happy. Most cases of active Valley Fever resemble a minor touch of the flu, though the majority of those exposed show absolutely no symptoms of any kind of illness; it is important to note, of course, that in rather rare instances Valley Fever can progress to a severe and serious infection, causing high fever, chills, unending fatigue, rapid weight loss, inflammation of the joints, meningitis, pneumonia and even death. Every fossil enthusiast who chooses to visit the Mojave Desert must be fully aware of the risks involved.

The Coso Contents

Coso Range Wilderness Map

Coso Range Wilderness: Wilderness.net

Details pertaining to the Coso Range Wilderness in Inyo County, California.

 Topographic Location Map

A PDF file of a portion of the Olancha 15 minute topographic quadrangle map showing a portion of the fossil-bearing area in the Coso Range Wilderness, courtesy of the California Geological Survey; you will need the free version of Adobe's Acrobat Reader to access the file. This map originally appeared in an article in the Mineral Information Service (later called California Geology), a publication issued by the California Geological Survey.

 Geologic Location Map

A PDF file of a portion of California Division of Mines and Geology Survey Map Sheet 38, Geology of the Keeler 15' Quadrangle Inyo County, California, by Melvine C. Stinson, 1977, courtesy of the California Geological Survey--a map that shows the general location of the vertebrate fossil area in the Coso Range Wilderness area. You will need the free version of Adobe's Acrobat Reader to access the file.

On-Site Images

View some  pictures taken in the Coso Range and in Olancha, California.

Fossil Bones Images

Take a look at some pictures of vertebrate fossils that have been found in the Upper Miocene to Middle Pliocene Coso Formation, Coso Mountains, Inyo County, California.

Fossil Horse Reconstruction

View a skeletal reconstruction of the Hagerman Horse, Equus simplicidens, the most common fossil vertebrate found in the Coso Formation. Image courtesy of Hagerman Fossil Beds National Monument.

Fossil Algae Images

Pictures of fossil algae accumulations from the Upper Miocene to Middle Pliocene Coso Formation, Inyo County, California.

Coso Fossil Mysteries

Take a look at some mystery fossils from the Pliocene Coso Formation, specimens collected several years ago from exposures that were at that date not included in the Coso Range Wilderness. If you happen to know what they are, let me know.

 List Of Vertebrate Fossils

A page which lists the species of vertebrate fossils paleontologists have recovered from the Lower to Middle Pliocene portions (4.8 to 3.0 million years old) of the Coso Formation.

 Crowley Point Pollen List

A page which lists the fossil pollens identified from the Crowley Point Florule in the Middle Pliocene portion of the Coso Formation, Inyo County, California.

Darwin Summit Pollen List

A page which lists the fossil pollens identified from the Darwin Summit Florule in the Middle Pliocene section (roughly 3.0 million years old) of the Coso Formation, Inyo County, California.

 Haiwee Pollen List

A page which lists the fossil pollens identified from the Haiwee Florule in the Middle Pliocene portion (roughly 3.0 million years old) of the Coso Formation, Inyo County, California.

 Panamint Springs Pollen List

A page which lists the fossil pollens identified from the Panamint Spring Florule in the Middle Pliocene section (roughly 3.0 million years old) of the Coso Formation, Inyo County, California.

 The Coso Flora

Read pertinent excerpts from the scientific paper, Late Pliocene floras east of the Sierra Nevada, by D. I. Axelrod and W. S. Ting, 1960, Univ. Calif. Pub. Geol. Sci. v. 39.

 USGS Bulletin 1527

An online version of United States Geological Survey Bulletin 1527, Age of the Coso Formation, Inyo County, California, by Charles R. Bacon, Dennis M. Giovannetti, Wendell A. Duffield, G. Brent Dalrymple, and Robert E. Drake, originally issued in 1982--a Public Domain document. It is here presented in PDF document format, which means that you'll need the free version of Adobe's Acrobat Reader to access the files.

 Links To The Pliocene

A list of Internet resources pertaining to the Pliocene Epoch of the Tertiary Period, Cenozoic Era, which lasted from roughly 5.0 to 1.8 million years ago.

Olancha And Coso Links

Links of interest pertaining to the community of Olancha, southern Owens Valley, Inyo County, California--gateway to the Coso Range Wilderness area; also, links to the Coso Range, with a special emphasis on the world-famous petroglyph rock art found there.

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Visit my other fossils-related Web pages I have created.

 My E-Mail Address

Contact me in cyberspace. Comments, suggestions, or questions are all welcomed.

 Introduction

An artist's reconstruction of an extinct horse formerly known as Plesippus, but now called Equus simplicidens, one of the most abundant vertebrate fossil remains found in the Pliocene Coso Formation, roughly 3.0 million years old. It is considered the earliest member of the genus Equus, which includes the modern horse and all other equids.

Here is an image taken several miles northeast of Olancha, Inyo County, California. The view is roughly southeastward to the northern end of the Coso Mountains, within which significant lower to middle Pliocene vertebrate fossil localities occur in the Coso Formation, a predominantly sedimentary rock unit (deposited in lakes, streams and as alluvial fans) that has been dated radiometrically at roughly 6.0 to 3.0 million years old. The Coso Formation contains one of California's best Blancan Stage (roughly 4.5 to 1.8 million years old) fossil mammal faunas, which occurs almost exclusively in the Coso Mountains--an extensive pristine desert district that has been included in the recently established Coso Range Wilderness. All of the vertebrate fossil localities lie within that protected area and are presently off-limits to everyone except professional paleontologists who possess valid collecting permits issued by the Bureau Of Land Management. The fossil vertebrate list includes the bones and teeth of several varieties of Pliocene mammals, including horses, rabbits, packrats, a vole, an extinct bear-dog, a llama, a peccary, a huge extinct bear and a mastodon. Also identified from the Coso Formation have been ostracodes (a minute bivalved crustacean), fish, unusual cabbage-like calcium carbonate accumulations that were precipitated by algae, diatoms, plus many pollen remains that have helped paleobotanists determine just what kind of plant life lived during Coso times roughly four and half to three million years ago, when the mammalian vertebrate remains were also accumulating. There is even tantalizing palynological (fossil pollen) evidence to indicate that the Pliocene Coso scene, some three million years ago, at least in part, closely resembled a modern Giant Sequoia forest along the western slopes of the Sierra Nevada mountain range in California.

At this Web site, you'll get a chance to explore the paleontological significance of the Coso Range--it's a rugged, wild desert land situated along the eastern side of the world-famous Owens Valley, and the great Sierra Nevada is in full, fantastic view to the immediate west. Peruse the Coso Menu at left and click on the links to get transported to different aspects of Coso discovery, from fossil bones and plants to world-class prehistoric petroglyph sites.

Special Note: All paleontological specimens figured at this Web site were observed in the ancient sediments long before the fossiliferous Coso Formation exposures were included in the Federally protected Coso Range Wilderness; today, according to Bureau Of Land Management regulations, visitors must not keep fossil specimens found within the Coso Range Wilderness lands without first securing a special use permit, a permit issued solely to qualified scientists, with at least a B.S. degree, from accredited universities and/or museums seeking to undertake research that can be fully verified by independent officials.

Bibliography

Helpful references about the Coso Formation:

Axelrod, D. I. and Ting, W. S., 1960, Late Pliocene floras east of the Sierra Nevada. Univ. Calif. Pub. Geol. Sci. 39, p. 1-118.

Bacon, C. R. , and Duffield, W. A., 1978, Soft-sediment deformation near the margin of basalt sill in the Pliocene Coso Formation, Inyo County, California: Geological Society of America Abstracts with Programs v. 10, no. 3, p. 103.

Bacon, C. R., Giovannetti, D. M. , Duffield, W. A., and Dalrymple, G.B., 1979, New Constraints on the Age of the Coso Formation, Inyo County, California: Geological Society of America Abstracts with programs, v. 11, no. 3 p. 67.

Bacon, C. R. , Giovannetti, D. M., Duffield, W. A., Dalrymple, W. A. and Drake R. E., United States Geological Survey Bulletin 1527, Age of the Coso Formation, Inyo County, California, 1982.

Duffield, W. A., and Bacon, C. R.,1981, Geologic map of the Coso volcanic field and adjacent areas, Inyo County, California: United States Geologic Survey Map I-1200, Scale 1:50,000.

Dunne, G. C., 1986, Geologic evolution of the southern Inyo Range, Darwin Plateau, and Argus and Slate Ranges, east-central California: An overview, in Dunne, G. C., eds., Mesozoic and Cenozoic Structural Evolution of Selected Areas, East-Central California: Los Angeles, Geological Society of America Cordilleran Section Field Trip Guidebook, p. 3-21.

Everden, J. F., et al, 1964, Potassium-argon dates and the Cenozoic mammalian chronology of North America. Amer. Jour. Sci., 262.

Hall, W. E., and Mackevett, E. M., Jr., 1962, Geology and ore deposits of the Darwin quadrangle, Inyo County, California: United States Geological Survey Professional Paper 368, 87 p.

Power, W. R. Jr., 1961, Backset beds in the Coso Formation, Inyo County, California,: Journal of Sedimentary Petrology, v. 31, p. 603-607.

Shultz, J. R., 1937, A late Cenozoic vertebrate fauna from the Coso Mountains, Inyo County, California. Carnegie Inst. Wash. Publ. 487.

Stinson, M. C. 1964, A Trip To A Vertebrate Fossil Locality, California Division of Mines and Geology Mineral Service, v. 17, no. 9, p. 160-163.

Stinson, M. C., 1977, Geology of the Haiwee Reservoir 15' Quadrangle, Inyo County, California, California Division of Mines and Geology Map Sheet 37.

Stinson, M. C., 1977, Geology of the Keeler 15' Quadrangle, Inyo County, California, California Division of Mines and Geology Map Sheet 38.

Walker, J. D., Whitmarsh, R. S., 1997, MAPPING AND GEOLOGIC INTERPRETATION IN THE COSO GEOTHERMAL AREA, Isotope Geochemistry Laboratory and Department of Geology, University of Kansas.

Wilson, R. W., 1932, Cosomys, a new genus of vole from the Pliocene of California, Jour. Mammology, 13.Whitmarsh, R.S., Walker, J.D., Monastero, F.C., 1996, Structural domains within the Coso Range: A case for right-oblique extension: Geological Society of America Abstracts with Programs, v. 28, no. 7, p. A-116.

Whitmarsh, R. S., 1997, GEOLOGIC MAP OF THE CENTENNIAL CANYON 7.5' QUADRANGLE; INYO COUNTY, CALIFORNIA.

Whitmarsh, R. S., 1997, GEOLOGIC MAP OF THE VERMILLION CANYON 7.5' QUADRANGLE; INYO COUNTY, CALIFORNIA.

Woodburne, M. O., 1971,Vertebrate Paleontology of the Northern Mojave Desert, Southern California: Field Trip Guide From Death Valley To Riverside, California, March 1971, in Geological Excursions in Southern California, University California Riverside Museum, p. 49-50.

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