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Early Triassic Ammonoid Fossils In Nevada

Find Abundant 248-Million Year Old Ammonoids

The Field Trip

In the backcountry wilds of Nevada occur two truly classic Early Triassic ammonoid localities. Both sites yield innumerable beautifully preserved ammonoids--an extinct order of cephalopod--in what geologists, stratigraphers and fossil cephalopod researchers all call the Lower Triassic Thaynes Formation, roughly 248 million years old, deposited near the beginning of the Mesozoic Era only three or four million years after the close of the preceding Paleozoic Era. The Thaynes is exposed at several localities in the rugged mountain ranges of the Great Basin, yet only one lone specific place in Nevada produces abundant Early Triassic ammonoids of such unprecedented exceptional preservation.

Of course, both Nevada Thaynes localities remain highly regarded among ammonoid specialists. Each experiences rather regular visitation from paleontologists the world-over, although admittedly that single unparalleled ammonoid locality is not only the finest Early Triassic ammonoid-bearing site in North America, but also one of the great Mesozoic Era cephalopod horizons known to exist, in general--all of this, mind you, despite the fact that its overall aerial sedimentary outcrop is confined to a meager few square acres within an isolated canyon. The entire stratigraphic section lies within what ammonoid enthusiasts call the Meekoceras and Anisibirites Zones--units of cephalopod-bearing rocks in which the ammonoids Meekoceras gracilitatus and Anasibirites kingianis are the most defining characteristic specimens encountered.

What makes that single ammonoid locality so significant in a paleontological context is that nowhere in North America are the world-famous Meekoceras beds exposed through anywhere near the thickness that they are at the fossil-rich section. Through roughly 175 feet of exposed strata, abundant ammonoids representing the Meekoceras Zone can be found. At the most fossiliferous and famous of the Early Triassic geologic sections, the extinct cephalopods occur in three of the seven limestone beds in the lowermost portions of Lower Triassic Thaynes Formation. Above that principally carbonate interval, the Thaynes consists of several hundred feet of thin-bedded grayish brown to tan shales in which organic remains of any kind are completely absent.

Geologic research completed in the late 20th Century, though, demonstrated pretty convincingly that the renowned fossiliferous section consists of several faulted, fractured and vertically displaced blocks, and at least one of the blocks is overturned. The upshot here is that contrary to conclusions conveyed by early geological investigations, there are only two ammonoid-bearing horizons at the locality, not several separate zones as previously determined. Still and all, stratigraphers agree that the Nevada Meekoceras zone can be confidently correlated with several additional notable occurrences around the globe, places such as: the Olenek-Lena River Basin in Siberia; Okhostsk-Kolyma Land, Siberia; Japan; Kwangai, China; Timor; New Zealand; Himalayas, India; Salt Range, Pakistan; Barabanja, Madagascar; northern Caucasus Mountains; Arctic Canada; and former Yugoslavia.

It's a stratigraphic section that continues to receive considerable attention from successive waves of geology students, who've mapped its sedimentary intricacies with great detail, many times over.

And so, the Thaynes ammonoid-bearing sequence is now very well known. At that most-special of ammonoid-bearing localities at that isolated Nevada canyon, the Thaynes Formation is formally subdivided into seven distinct mappable lithologic units, called Members "a" through "g."

The uppermost, or youngest fossiliferous bed in the Thaynes is termed member "g." It's roughly 12 feet of gray calcium carbonate that tends to weather into shades of dark brown, a fine to medium-crystalline limestone characterized by thick to irregular bedding, and fragmental and complete ammonoid conchs occur throughout. While the cephalopods are perhaps not as well preserved as their counterparts in the oldest member at the measured section, at least eight species of ammonoids have been described from the rich interval, including Juvenites septentrionalis, Owenities koeneni, Owenoites stokesi, Parannanites mulleri, Pseudosageceras multilobatum, Meekoceras gracilitatus, Flemingites russeli, and Wyomingites arnoldi.

Unit "f," just below the fossiliferous "g" member, is a barren interval of fine to medium-crystalline light gray limestone some 48 feet thick; it is frequently difficult to distinguish "f" and "g" from a distance, but the uniformly unfossilferous nature of "f" suggests that if you come upon it in the field you should walk up section a short distance, through the barren carbonates to intersect the productive limestones of member "g" above it.

Next oldest unit in the Thaynes section is member "e," a rusty-brown weathering fine to medium crystalline limestone roughly 45 feet thick that produces abundant remains of a genuine "living fossil"--the inarticulate brachiopod called Lingula, which most paleontologists believe represents one of the great survivors of geologic time. It's a species that has persisted through the eons when many other perhaps more glamorous creatures such as the dinosaur, the trilobite and the ammonite vanished from Earth many millions of years ago. Resembling a slender fingernail, Lingula first appears in the fossil record during the Early Cambrian Period, approximately 520 million years ago. It has survived unchanged in physical appearance for all that time.

Immediately below the productive Lingula zone lies the second ammonoid-rich layer, unit "d." This is a fine to medium-crystalline light-gray limestone some 15 feet in thickness, massively bedded with slabby partings. And it is everywhere crammed with plentiful cephalopodic remains, mostly fragmental; but the coquinoid nature of member "d" keeps many collectors busy for hours at a time, gently cracking the organic-rich carbonates to free the prized ammonoids within. Paleontologists have identified eight species of ammonoids from the horizon: Juvenites septentrionalis, Aspenites acutis, Owenites koeni, Inyoites stokesi, Paranannites mulleri, Meekoceras gracilitatus, Wyomingites aplanatus, and Preflorianites toulai.

The successively older Thaynes stratigraphic units "c" and "b" are both poorly exposed--and unfossiliferous. They have a combined thickness of roughly 30 feet, consisting of pale gray limestone and occasional micaceous calcareous shales that tend to weather into platey slabs.

But the underlying unit "a," which reaches a maximum development of some 33 feet, is abundantly fossiliferous with both broken and complete cephalopods. As a matter of fact, approximately half or more of the light-gray to brown-weathering limestone, characterized by frequent limonitic flecks and partings, is composed of ammonoid remains. It is indeed a stunning deposit that innumerable fossil collectors have visited over a period of many decades. As a consequence, horizon "a" has suffered an appreciable ammonoid attrition; the perfect fossils have become increasingly difficult to find, especially the larger showy shells, several inches in diameter, for which commercial dealers pay top dollar.

Editorial time now, I reckon: There is obviously no way to prevent commercial fossil collectors from visiting the area, but one can only make the obvious observation that if the desecration trend continues there won't be much left to find there except unidentifiable fragments. For the benefit of all conscientious paleontology enthusiasts, commercial collectors must keep their distance, or the Bureau of Land Management (BLM) will surely close it all down, enacting severe restrictions on who can keep what they find there.

Member "a" of the Thaynes Formation is justifiably a world-famous ammonoid deposit; some 23 species have been described from it, including Dieneroceras (three species), Xenocelities (two species), Juvenites (two species), Meekoceras gracilitatus, Hemiaspinites obtusus, Flemingites russeli, Anaflemingites silberlingi, Preflorianites toulai, Pseudospidites wheeleri, Owenites koeneni, Paranannites apenensis, Prophingites slossi, Parussuria compressa, Lanceolites compactus, Aspenites acutis, Wyomingites whiteanus, Arctoceras tuberculum, Arctoprionites sp. and Pseudosageceras multilobatum.

Of course, it should be noted here that several stratigraphers believe that the three ammonoid-bearing limestone beds of the Thaynes Formation constitute in actual fact but a single calcium carbonite horizon--not three distinct units--now separated though faulting at that prime Nevada section into disjointed outcrop blocks that mimic mappable geologic formation members.

A second major Early Triassic Thaynes ammonoid locality also occurs in Nevada. Even though it's certainly not nearly as well known to collectors as the primary locality, sporadic waves of avid fossil enthusiasts nonetheless continue to successfully find their way to the reliably productive ammonoid-bearing Thaynes Formation deposits, approximately 248 million years old.

An encouraging bit of news it that at last visit this second Nevada section could still be found in essentially pristine stratigraphic condition, despite the fact that the ammonoidiferous horizons have been known to fossil hunters since at least the late 1800s. For example, legendary Triassic ammonoid specialist James Perrin Smith first visited the locality in the early 1900s and took away loads of identifiable cephalopods.

The ammonoids occur, of course, in the Lower Triassic Thaynes Formation, which is sporadically exposed throughout a specific geographic area of Nevada. In California, noteworthy outcrops of ammonoid-bearing Early Triassic strata can also be examined at Union Wash in the shadows of Mount Whitney (highest point in the contiguous United States); the paleontological material there resides in the Union Wash Formation. And Early Triassic ammonoids occur in western Utah, as well--see Kevin Byland's page, Fossil Cephalopods In Utah.

At the two ammonoid localities in Nevada's Early Triassic Thaynes Formation, it is intriguing to reflect that in the context of deep geologic time the roughly 248 million year-old animals you find there lived "only" three to four million years after the greatest mass extinction ever recorded in the rocks--the traumatic end time Permian Period of 252 million years ago, when fully 96 percent of all life on Earth died out. An ammonoid you hold in your hand survived it all, and lived on to eventually weather out of the Thaynes limestones that gave it a kind of immortality.

On-Site Images

Click on the images for larger pictures

Click on the image for a larger picture. A seeker of Early Triassic cephalopodic ammonoids hikes up the fossiliferous limestone slopes at one of two classic Early Triassic ammonoid localities discussed at this Web page. Practically every chunk of limestone along that slope contains broken and complete ammonoids in the Lower Triassic Thaynes Formation.

Click on image for a larger picture. An invertebrate paleontology enthusiast collects ammonoids from the productive limestone ledges in the Lower Triassic Thaynes Formation, Nevada; not every carbonate layer here yields cephalopods, but there are enough fossiliferous sections to keep everybody happy for hours on end.

Click on the image for a larger picture. Here's a scenic overview of one of the famous ammonoid localities in the Lower Triassic Thaynes Formation, Nevada; the view is southwest to the richly fossiliferous Thaynes outcrops roughly just below dead-center of the photograph at the inclined, dark narrow strip along the hillslope in middle distance.

Click on the images for larger pictures. Left to right--An adventurer of Early Triassic times explores the exceptionally fossiliferous Member "a" of the Lower Triassic Thaynes Formation, Nevada; it is not an exaggeration to say that every chunk of limestone in this view contains fragmental and complete ammonoids. Right--A Great Basin fossil enthusiast investigates a highly fossiliferous Lower Triassic Thaynes Formation exposure in Nevada--one of the two specific localities discussed in the field trip text.

Click on the image for a larger picture. A classic ammonoid locality in the Lower Triassic Thaynes Formation of Nevada; the limestone ledge at right produces prodigious quantities of quality Early Triassic cephalopods.

Images Of Early Triassic Ammonoids

Lower Triassic Thaynes Formation, 248 Million Years Old


At left: an ammonoid from the Lower Triassic Thaynes Formation, Nevada, Dienoroceras spathi. At right: an ammonoid from the Lower Triassic Thaynes Formation, Nevada, Meekoceras gracilitatus--the specific species for which the world-famous Meekoceras beds were named.

At left: an ammonoid from the Lower Triassic Thaynes Formation, Nevada, Wymomingites whiteanus. At right: an ammonoid from the Lower Triassic Thaynes Formation, Nevada, Aspenites acutis.

At left: an ammonoid from the Lower Triassic Thaynes Formation, Nevada.  Dienoroceras knechti. At right: an ammonoid from the Lower Triassic Thaynes Formation, Nevada, Inyoites stokesi.

At left: an ammonoid from the Lower Triassic Thaynes Formation, Nevada. Dienoroceras subquadratum; this specimen, incredibly, shows some of its original color markings. At right: An ammonoid from the Lower Triassic Thaynes Formation, Nevada. Inyoites stokesi.

Click on the image for a larger picture. Different views of nine ammonoids from the Lower Triassic Thaynes Formation, Nevada. Scale bar equals one centimeter (0.39 inch). Called scientifically, Elkoceras spathi. Photograph courtesy a specific technical document.

Click on the image for a larger picture. Different views of two ammonoids from the Lower Triassic Thaynes Formation, Nevada. Scale bar equals one centimeter (0.39 inch). Called scientifically, Pseudosageceras multilobatum. Photograph courtesy a specific technical document.

Click on the image for a larger picture. Different views of four ammonoids from the Lower Triassic Thaynes Formation, Nevada. Scale bar equals one centimeter (0.39 inch). Called scientifically, Juvenites spathi. Photograph courtesy a specific technical document.

Click on the image for a larger picture. Different views of 13 ammonoids from the Lower Triassic Thaynes Formation, Nevada. Scale bar equals one centimeter (0.39 inch). Called scientifically, Juvenites septentrionalis. Photograph courtesy a specific technical document.

Click on the image for a larger picture. Different views of seven ammonoids from the Lower Triassic Thaynes Formation, Nevada. Scale bar equals one centimeter (0.39 inch). Called scientifically, Owenites koeneni. Photograph courtesy a specific technical document.

Click on the image for a larger picture. Different views of eight ammonoids from the Lower Triassic Thaynes Formation, Nevada. Scale bar equals one centimeter (0.39 inch). Called scientifically, Preflorianites toulai. Photograph courtesy a specific technical document.

Click on the image for a larger picture. Different views of seven ammonoids from the Lower Triassic Thaynes Formation, Nevada. Scale bar equals one centimeter (0.39 inch). Called scientifically, Proharpoceras carinatitabulatatum. Photograph courtesy a specific technical document.

BLM Rules

For information on what can and cannot be collected legally from America's Public Lands, take a look at Fossils On America's Public Lands and Collecting On Public Lands--brochures that the Bureau Of Land Management has allowed me to transcribe.

My Other Web Sites

My Music Pages

Paleontology-Related Pages

Web sites I have created pertaining to fossils

  • Fossils In Death Valley National Park: A site dedicated to the paleontology, geology, and natural wonders of Death Valley National Park; lots of on-site photographs of scenic localities within the park; images of fossils specimens; links to many virtual field trips of fossil-bearing interest.
  • Fossil Insects And Vertebrates On The Mojave Desert, California: Journey to two world-famous fossil sites in the middle Miocene Barstow Formation: one locality yields upwards of 50 species of fully three-dimensional, silicified freshwater insects, arachnids, and crustaceans that can be dissolved free and intact from calcareous concretions; a second Barstow Formation district provides vertebrate paleontologists with one of the greatest concentrations of Miocene mammal fossils yet recovered from North America--it's the type locality for the Bartovian State of the Miocene Epoch, 15.9 to 12.5 million years ago, with which all geologically time-equivalent rocks in North American are compared.
  • A Visit To Fossil Valley, Great Basin Desert, Nevada: Take a virtual field trip to a Nevada locality that yields the most complete, diverse, fossil assemblage of terrestrial Miocene plants and animals known from North America--and perhaps the world, as well. Yields insects, leaves, seeds, conifer needles and twigs, flowering structures, pollens, petrified wood, diatoms, algal bodies, mammals, amphibians, reptiles, bird feathers, fish, gastropods, pelecypods (bivalves), and ostracods.
  • Fossils At Red Rock Canyon State Park, California: Visit wildly colorful Red Rock Canyon State Park on California's northern Mojave Desert, approximately 130 miles north of Los Angeles--scene of innumerable Hollywood film productions and commercials over the years--where the Middle to Late Miocene (13 to 7 million years old) Dove Spring Formation, along with a classic deposit of petrified woods, yields one of the great terrestrial, land-deposited Miocene vertebrate fossil faunas in all the western United States.
  • Cambrian And Ordovician Fossils At Extinction Canyon, Nevada: Visit a site in Nevada's Great Basin Desert that yields locally common whole and mostly complete early Cambrian trilobites, in addition to other extinct organisms such as graptolites (early hemichordate), salterella (small conical critter placed in the phylum Agmata), Lidaconus (diminutive tusk-shaped shell of unestablished zoological affinity), Girvanella (photosynthesizing cyanobacterial algae), and Caryocaris (a bivalved crustacean).
  • Late Pennsylvanian Fossils In Kansas: Travel to the midwestern plains to discover the classic late Pennsylvanian fossil wealth of Kansas--abundant, supremely well-preserved associations of such invertebrate animals as brachiopods, bryozoans, corals, echinoderms, fusulinids, mollusks (gastropods, pelecypods, cephalopods, scaphopods), and sponges; one of the great places on the planet to find fossils some 307 to 299 million years old.
  • Fossil Plants Of The Ione Basin, California: Head to Amador County in the western foothills of California's Sierra Nevada to explore the fossil leaf-bearing Middle Eocene Ione Formation of the Ione Basin. This is a completely undescribed fossil flora from a geologically fascinating district that produces not only paleobotanically invaluable suites of fossil leaves, but also world-renowned commercial deposits of silica sand, high-grade kaolinite clay and the extraordinarily rare Montan Wax-rich lignites (a type of low grade coal).
  • Ice Age Fossils At Santa Barbara, California--Journey to the famed So Cal coastal community of Santa Barbara (about a 100 miles north of Los Angeles) to explore one of the best marine Pleistocene invertebrate fossil-bearing areas on the west coast of the United States; that's where the middle Pleistocene Santa Barbara Formation yields nearly 400 species of pelecypod bivalve mollusks, gastropods, chitons, scaphopods, pteropods, brachiopods, bryozoans, corals, ostracods (minute bivalve crustaceans), worm tubes, and foraminifers.
  • Trilobites In The Marble Mountains, Mojave Desert, California: Take a trip to the place that first inspired my life-long fascination and interest in fossils--the classic trilobite quarry in the Lower Cambrian Latham Shale, in the Marble Mountains of California's Mojave Desert. It's a special place, now included in the rather recently established Trilobite Wilderness, where some 21 species of ancient plants and animals have been found--including trilobites, an echinoderm, a coelenterate, mollusks, blue-green algae and brachiopods.
  • Fossil Plants In The Neighborhood Of Reno, Nevada: Visit two famous fossil plant localities in the Great Basin Desert near Reno, Nevada--a place to find leaves, seeds, needles, foilage, and cones in the middle Miocene Pyramid and Chloropagus Formations, 15.6 and 14.8 to 13.3 million years old, respectively.
  • Dinosaur-Age Fossil Leaves At Del Puerto Creek, California: Journey to the western edge of California's Great Central Valley to explore a classic fossil leaf locality in an upper Cretaceous section of the upper Cretaceous to Paleocene Moreno Formation; the plants you find there lived during the day of the dinosaur.
  • Early Cambrian Fossils Of Westgard Pass, California: Visit the Westgard Pass area, a world-renowned geologic wonderland several miles east of Big Pine, California, in the neighboring White-Inyo Mountains, to examine one of the best places in the world to find archaeocyathids--an enigmatic invertebrate animal that went extinct some 510 million years ago, never surviving past the early Cambrian; also present there in rocks over a half billion years old are locally common trilobites, plus annelid and arthropod trails, and early echinoderms.
  • Plant Fossils At The La Porte Hydraulic Gold Mine, California: Journey to a long-abandoned hydraulic gold mine in the neighborhood of La Porte, northern Sierra Nevada, California, to explore the upper Eocene La Porte Tuff, which yields some 43 species of Cenozoic plants, mainly a bounty of beautifully preserved leaves 34.2 million years old.
  • A Visit To Ammonite Canyon, Nevada: Explore one of the best-exposed, most complete fossiliferous marine late Triassic through early Jurassic geologic sections in the world--a place where the important end-time Triassic mass extinction has been preserved in the paleontological record. Lots of key species of ammonites, brachiopods, corals, gastropods and pelecypods.
  • Fossil Plants At The Chalk Bluff Hydraulic Gold Mine, California: Take a field trip to the Chalk Bluff hydraulic gold mine, western foothills of California's Sierra Nevada, for leaves, seeds, flowering structures, and petrified wood from some 70 species of middle Eocene plants.
  • Field Trip To The Alexander Hills Fossil District, Mojave Desert, California: Visit a locality outside the southern sector of Death Valley National Park to explore a paleontological wonderland that produces: Precambrian stromatolites over a billion years old; early skeletonized eukaryotic cells of testate amoebae over three-quarters of billion years old; early Cambrian trilobites, archaeocyathids, annelid trails, arthropod tracks, and echinoderm material; Pliocene-Pleistocene vertebrate and invertebrate faunas; and late middle Miocene camel tracks, petrified palm wood, petrified dicotlyedon wood, and permineralized grasses.
  • Fossils In Millard County, Utah: Take virtual field trips to two world-famous fossil localities in Millard County, Utah--Wheeler Amphitheater in the trilobite-bearing middle Cambrian Wheeler Shale; and Fossil Mountain in the brachiopod-ostracod-gastropod-echinoderm-trilobite rich lower Ordovician Pogonip Group.
  • Fossil Plants, Insects And Frogs In The Vicinity Of Virginia City, Nevada: Journey to a western Nevada badlands district near Virginia City and the Comstock Lode to discover a bonanza of paleontology in the late middle Miocene Coal Valley Formation.
  • Paleozoic Era Fossils At Mazourka Canyon, Inyo County, California: Visit a productive Paleozoic Era fossil-bearing area near Independence, California--along the east side of California's Owens Valley, with the great Sierra Nevada as a dramatic backdrop--a paleontologically fascinating place that yields a great assortment of invertebrate animals.
  • Late Triassic Ichthyosaur And Invertebrate Fossils In Nevada: Journey to two classic, world-famous fossil localities in the Upper Triassic Luning Formation of Nevada--Berlin-Ichthyosaur State Park and Coral Reef Canyon. At Berlin-Ichthyosaur, observe in-situ the remains of several gigantic ichthyosaur skeletons preserved in a fossil quarry; then head out into the hills, outside the state park, to find plentiful pelecypods, gastropods, brachiopods and ammonoids. At Coral Reef Canyon, find an amazing abundance of corals, sponges, brachiopods, echinoids (sea urchins), pelecypods, gastropods, belemnites and ammonoids.
  • Fossils From The Kettleman Hills, California: Visit one of California's premiere Pliocene-age (approximately 4.5 to 2.0 million years old) fossil localities--the Kettleman Hills, which lie along the western edge of California's Great Central Valley northwest of Bakersfield. This is where innumerable sand dollars, pectens, oysters, gastropods, "bulbous fish growths" and pelecypods occur in the Etchegoin, San Joaquin and Tulare Formations.
  • Field Trip To The Kettleman Hills Fossil District, California: Take a virtual field trip to a classic site on the western side of California's Great Central Valley, roughly 80 miles northwest of Bakersfield, where several Pliocene-age (roughly 4.5 to 2 million years old) geologic rock formations yield a wealth of diverse, abundant fossil material--sand dollars, scallop shells, oysters, gastropods and "bulbous fish growths" (fossil bony tumors--found nowhere else, save the Kettleman Hills), among many other paleontological remains.
  • A Visit To The Sharktooth Hill Bone Bed, Southern California: Travel to the dusty hills near Bakersfield, California, along the eastern side of the Great Central Valley in the western foothills of the Sierra Nevada, to explore the world-famous Sharktooth Hill Bone Bed, a Middle Miocene marine deposit some 16 to 15 million years old that yields over a hundred species of sharks, rays, bony fishes, and sea mammals from a geologic rock formation called the Round Mountain Silt Member of the Temblor Formation; this is the most prolific marine, vertebrate fossil-bearing Middle Miocene deposit in the world.
  • High Sierra Nevada Fossil Plants, Alpine County, California: Visit a remote fossil leaf and petrified wood locality in the Sierra Nevada, at an altitude over 8,600 feet, slightly above the local timberline, to find 7 million year-old specimens of cypress, Douglas-fir, White fir, evergreen live oak, and giant sequoia, among others.
  • In Search Of Fossils In The Tin Mountain Limestone, California: Journey to the Death Valley area of Inyo County, California, to explore the highly fossiliferous Lower Mississippian Tin Mountain Limestone; visit three localities that provide easy access to a roughly 358 million year-old calcium carbate accumulation that contains well preserved corals, brachiopods, bryozoans, crinoids, and ostracods--among other major groups of invertebrate animals.
  • Middle Triassic Ammonoids From Nevada: Travel to a world-famous fossil locality in the Great Basin Desert of Nevada, a specific place that yields some 41 species of ammonoids, in addition to five species of pelecypods and four varieties of belemnites from the Middle Triassic Prida Formation, which is roughly 235 million years old; many paleontologists consider this specific site the single best Middle Triassic, late Anisian Stage ammonoid locality in the world. All told, the Prida Formation yields 68 species of ammonoids spanning the entire Middle Triassic age, or roughly 241 to 227 million years ago.
  • Late Miocene Fossil Leaves At Verdi, Washoe County, Nevada: Explore a fascinating fossil leaf locality not far from Reno, Nevada; find 18 species of plants that prove that 5.8 million years ago this part of the western Great Basin Desert would have resembled, floristically, California's lush green Gold Country, from Placerville south to Jackson.
  • Fossils Along The Loneliest Road In America: Investigate the extraordinary fossil wealth along some 230 miles of The Loneliest Road In America--US Highway 50 from the vicinity of Eureka, Nevada, to Delta in Millard County, Utah. Includes on-site images and photographs of representative fossils (with detailed explanatory text captions) from every geologic rock deposit I have personally explored in the neighborhood of that stretch of Great Basin asphalt. The paleontologic material ranges in geologic age from the middle Eocene (about 48 million years ago) to middle Cambrian (approximately 505 million years old).
  • Fossil Bones In The Coso Range, Inyo County, California: Visit the Coso Range Wilderness, 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.
  • Field Trip To A Vertebrate Fossil Locality In The Coso Range, California: Take a cyber-visit to the famous bone-bearing Pliocene Coso Formation, Coso Mountains, Inyo County, California; includes detailed text for the field trip, plus on-site images and photographs of vertebrate fossils.
  • Fossil Plants At Aldrich Hill, Western Nevada: Take a field trip to western Nevada, in the vicinity of Yerington, to famous Aldrich Hill, where one can collect some 35 species of ancient plants--leaves, seeds and twigs--from the Middle Miocene Aldirch Station Formation, roughly 12 to 13 million years old. Find the leaves of evergreen live oak, willow, and Catalina Ironwood (which today is restricted in its natural habitat solely to the Channel Islands off the coast of Southern California), among others, plus the seeds of many kinds of conifers, including spruce; expect to find the twigs of Giant Sequoias, too.
  • Fossils From Pleistocene Lake Manix, California: Explore the badlands of the Manix Lake Beds on California's Mojave Desert, an Upper Pleistocene deposit that produces abundant fossil remains from the silts and sands left behind by a great fresh water lake, roughly 350,000 to 19,000 years old--the Manix Beds yield many species of fresh water mollusks (gastropods and pelecypods), skeletal elements from fish (the Tui Mojave Chub and Three-Spine Stickleback), plus roughly 50 species of mammals and birds, many of which can also be found in the incredible, world-famous La Brea Tar Pits of Los Angeles.
  • Field Trip To Pleistocene Lake Manix, California: Go on a virtual field trip to the classic, fossiliferous badlands carved in the Upper Pleistocene Manix Formation, Mojave Desert, California. It's a special place that yields beaucoup fossil remains, including fresh water mollusks, fish (the Mojave Tui Chub), birds and mammals.
  • Trilobites In The Nopah Range, Inyo County, California: Travel to a locality well outside the boundaries of Death Valley National Park to collect trilobites in the Lower Cambrian Pyramid Shale Member of the Carrara Formation.
  • Ammonoids At Union Wash, California: Explore ammonoid-rich Union Wash near Lone Pine, California, in the shadows of Mount Whitney, the highest point in the contiguous United States. Union Wash is a ne plus ultra place to find Early Triassic ammonoids in California. The extinct cephalopods occur in abundance in the Lower Triassic Union Wash Formation, with the dramatic back-drop of the glacier-gouged Sierra Nevada skyline in view to the immediate west.
  • A Visit To The Fossil Beds At Union Wash, Inyo County California: A virtual field trip to the fabulous ammonoid accumulations in the Lower Triassic Union Wash Formation, Inyo County, California--situated in the shadows of Mount Whitney, the highest point in the contiguous United States.
  • Ordovician Fossils At The Great Beatty Mudmound, Nevada: Visit a classic 475-million-year-old fossil locality in the vicinity of Beatty, Nevada, only a few miles east of Death Valley National Park; here, the fossils occur in the Middle Ordovician Antelope Valley Limestone at a prominent Mudmound/Biohern. Lots of fossils can be found there, including silicified brachiopods, trilobites, nautiloids, echinoderms, bryozoans, ostracodes and conodonts.
  • Paleobotanical Field Trip To The Sailor Flat Hydraulic Gold Mine, California: Journey on a day of paleobotanical discovery with the FarWest Science Foundation to the western foothills of the Sierra Nevada--to famous Sailor Flat, an abandoned hydraulic gold mine of the mid to late 1800s, where members of the foundation collect fossil leaves from the "chocolate" shales of the Middle Eocene auriferous gravels; all significant specimens go to the archival paleobotanical collections at the University California Museum Of Paleontology in Berkeley.
  • Early Cambrian Fossils In Western Nevada: Explore a 518-million-year-old fossil locality several miles north of Death Valley National Park, in Esmeralda County, Nevada, where the Lower Cambrian Harkless Formation yields the largest single assemblage of Early Cambrian trilobites yet described from a specific fossil locality in North America; the locality also yields archeocyathids (an extinct sponge), plus salterella (the "ice-cream cone fossil"--an extinct conical animal placed into its own unique phylum, called Agmata), brachiopods and invertebrate tracks and trails.
  • Fossil Leaves And Seeds In West-Central Nevada: Take a field trip to the Middlegate Hills area in west-central Nevada. It's a place where the Middle Miocene Middlegate Formation provides paleobotany enthusiasts with some 64 species of fossil plant remains, including the leaves of evergreen live oak, tanbark oak, bigleaf maple, and paper birch--plus the twigs of giant sequoias and the winged seeds from a spruce.
  • Ordovician Fossils In The Toquima Range, Nevada: Explore the Toquima Range in central Nevada--a locality that yields abundant graptolites in the Lower to Middle Ordovician Vinini Formation, plus a diverse fauna of brachiopods, sponges, bryozoans, echinoderms and ostracodes from the Middle Ordovician Antelope Valley Limestone.
  • Fossil Plants In The Dead Camel Range, Nevada: Visit a remote site in the vicinity of Fallon, Nevada, where the Middle Miocene Desert Peak Formation provides paleobotany enthusiasts with 22 species of nicely preserved leaves from a variety of deciduous trees and evergreen live oaks, in addition to samaras (winged seeds), needles and twigs from several types of conifers.
  • Early Triassic Ammonoid Fossils In Nevada: Visit the two remote localities in Nevada that yield abundant, well-preserved ammonoids in the Lower Triassic Thaynes Formation, some 248 million years old--one of the sites just happens to be the single finest Early Triassic ammonoid locality in North America.
  • Fossil Plants At Buffalo Canyon, Nevada: Explore the wilds of west-central Nevada, a number of miles from Fallon, where the Middle Miocene Buffalo Canyon Formation yields to seekers of paleontology some 54 species of deciduous and coniferous varieties of 15-million-year-old leaves, seeds and twigs from such varieties as spruce, fir, pine, ash, maple, zelkova, willow and evergreen live oak
  • High Inyo Mountains Fossils, California: Take a ride to the crest of the High Inyo Mountains to find abundant ammonoids and pelecypods--plus, some shark teeth and terrestrial plants in the Upper Mississippian Chainman Shale, roughly 325 million years old.
  • Field Trip To The Copper Basin Fossil Flora, Nevada: Visit a remote region in Nevada, where the Late Eocene Dead Horse Tuff provides seekers of paleobotany with some 42 species of ancient plants, roughly 39 to 40 million years old, including the leaves of alder, tanbark oak, Oregon grape and sassafras.
  • Fossil Plants And Insects At Bull Run, Nevada: Head into the deep backcountry of Nevada to collect fossils from the famous Late Eocene Chicken Creek Formation, which yields, in addition to abundant fossil fly larvae, a paleobotanically wonderful association of winged seeds and fascicles (bundles of needles) from many species of conifers, including fir, pine, spruce, larch, hemlock and cypress. The plants are some 37 million old and represent an essentially pure montane conifer forest, one of the very few such fossil occurrences in the Tertiary Period of the United States.
  • A Visit To The Early Cambrian Waucoba Spring Geologic Section, California: Journey to the northwestern sector of Death Valley National Park to explore the classic, world-famous Waucoba Spring Early Cambrian geologic section, first described by the pioneering paleontologist C.D. Walcott in the late 1800s; surprisingly well preserved 540-510 million-year-old remains of trilobites, invertebrate tracks and trails, Girvanella algal oncolites and archeocyathids (an extinct variety of sponge) can be observed in situ.
  • Petrified Wood From The Shinarump Conglomerate: An image of a chunk of petrified wood I collected from the Upper Triassic Shinarump Conglomerate, outside of Dinosaur National Monument, Colorado.
  • Fossil Giant Sequoia Foliage From Nevada: Images of the youngest fossil foliage from a giant sequoia ever discovered in the geologic record--the specimen is Lower Pliocene in geologic age, around 5 million years old.
  • Some Favorite Fossil Brachiopods Of Mine: Images of several fossil brachiopods I have collected over the years from Paleozoic, Mesozoic and Cenozoic-age rocks.
  • For information on what can and cannot be collected legally from America's Public Lands, take a look at Fossils On America's Public Lands and Collecting On Public Lands--brochures that the Bureau Of Land Management has allowed me to transcribe.
  • In Search Of Vanished Ages--Field Trips To Fossil Localities In California, Nevada, And Utah--My fossils-related field trips in full print book form (pdf). 98,703 words (equivalent to a medium-size hard cover work of non-fiction); 250 printed pages (equivalent to about 380 pages in hard cover book form); 27 chapters; 30 individual field trips to places of paleontological interest; 60 photographs--representative on-site images and pictures of fossils from each locality visited.

United States Geological Survey Papers (Public Domain)

Online versions of USGS publications

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