Middle Triassic Ammonoid Fossils From Nevada

Visit 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.

Also, take a side trip to a classic Late Pleistocene mollusk locality in Nevada, where beaucoup freshwater gastropods and pelecypods occur in the famous Sehoo Formation, approximately 24 to 13 thousand years old.

At left is Parafrenchites meeki, 18mm in diameter. At right is Paraceratites vogdesi, 19mm in diameter.

Contents For--Middle Triassic Ammonoid Fossils From Nevada:

 Images Of Prida Fm. Fossils  Images Of Prida Fm. Ammonoids  Images Of Prida Fm. Fossils In Matrix
On-Site Prida Fm. Images Images Of Sehoo Fm. Mollusks On-Site Sehoo Fm. Images
Ammonoids Geologic History Links To The Triassic Period Links To Ammonoids
BLM Rules For Fossil Collecting My Other Web Pages My Email Address

Geologic History Of Ammonoids

Based on their distinctive suture patterns (a suture is the juncture of the internal partition which separates the cephalopod shell chambers with the shell wall), all ammonoid and ammonite cephalopods can be classified into three separate orders: goniatitic (species with nonserrated sutures, generally considered the most primitive varieties); ceratitic (sutures with serrated lobes)--the kind found in the Middle Triassic Prida Formation discussed at this Web Page; and ammonitic (very complex suturing--usually referred to as the most advanced order of ammonites)--the only order that can properly be termed an ammonite; the goniatitic and ceratitic types are necessarily called ammonoids. The goniatites first appear in the geologic record during the Devonian Period, some 370 million years ago; they persisted all the way up to the great dying at the conclusion of the Permian Period (when trilobites finally disappeared, as well), 248 million years ago. During the Permian Period both ammonoid and the ammonite varieties became common. But by Triassic times (248 to roughly 206 million years ago), only the ceratitic forms proved particularly successful. They, too, died out at the conclusion of that geologic period, leaving only the ammonitic types, the ammonites proper, to carry on the cephalopodal heritage.

Throughout the Jurassic Period (195 to 150 million years ago) ammonitic ammonites thrived, becoming increasingly complex and numerous in the oceans of the Mesozoic world. And, even though ammonites began a long, slow decline over many millions of years during the latter part of the Cretaceous Period, they nevertheless persisted right up to the close of the Mesozoic Era (roughly 65 million years ago), becoming extinct along with all the sensational, terrestrial giants of that age--the dinosaur.

Images Of Fossils From The Prida Formation, Nevada

Middle Triassic (235 Million Years Old)

The fossils imaged here came an isolated outcrop of the Middle Triassic Prida Formation in Nevada on Public Lands (at least at the last time of collecting the site resided on Bureau of Land Management-administered Public Lands). It's a world-famous locality, well known to many amateur ammonoid enthusiasts and professional paleontologists alike--a specific place that yields 41 species of ammonoids, plus five kinds of pelecypods (a remarkable halobiid clam known as Daonella) and four varieties of belemnites; all told, the Prida Formation bears 68 species of ammonoids that span the entire middle Triassic age, or roughly 241 to 227 million years ago. As a matter of fact, the specific Prida Formation site referred to here yields one of the most complete middle Triassic ammonoid successions in the world; and many cephalopod specialists and paleontologists, in general, consider it the single best Middle Triassic, late Anisian Stage (roughly 235 million years old) ammonoid locality in existence. Literally tons of ammonoid-bearing limestones have been removed from the site since its discovery by silver miners in the latter half of the 1800s; that well-preserved, identifiable fossils still occur there, after such concerted searching by hordes of avid ammonoid enthusiasts over many decades, is somewhat of a miracle. In the late 1980s, for example, many law-abiding, conscientious amateur collectors, plus swarms of irresponsible, lawbreaking commercial ammonoid hunters (it is illegal to either sell or barter--in other words, trade--fossils collected on Public Lands) "simultaneously rediscovered" the great fossil locality, creating over the past couple of decades an often frenzied frequency of overcollecting.

The geologic age of the specific, classic ammonoid site is transitional latest Anisian/earliest Ladinian Stage of the Triassic Period, which places the fossils found there directly in the middle of the Mid Triassic, or roughly 235 million years old. At that distant geologic date, what is now the classic Prida fossil locality in the arid Great Basin Desert of Nevada rested at the bottom of a shallow, tropical, warmwater Triassic seaway near the equator.

Please Note: I have heard that the Bureau of Land Management carefully monitors fossil collecting activities at the incomparable MiddleTriassic Prida ammonoid outcrops: the upshot, accordingly, is that commercial fossil collectors caught raiding the Prida strata will most certainly be prosecuted to the fullest extent of the law. There has also been talk that, because commercial collectors have so horribly desecrated the area, the Bureau of Land Management will eventually place the world-class Prida ammonoid locality into a special land-use category called an "Area Of Critical Environmental Concern," a designation that would permanently close the site to all but trained scientists with a degree from an accredited university.

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.

Images Of Ammonoids Free Of Matrix

Middle Triassic Prida Formation, Nevada

Late Anisian/Early Ladinian Stage, 235 Million Years Old

AMMONOIDEA (Ammonoids)







Images Of Fossils Still In Limestone Matrix

Middle Triassic Prida Formation, Nevada

Late Anisian/Early Ladinian Stage, 235 Million Years Old

AMMONOIDEA (Ammonoids)








Images Of Nonammonoid Fossils In Limestone Matrix

Middle Triassic Prida Formation, Nevada

Late Anisian/Early Ladinian Stage, 235 Million Years Old




POSIDONIIDAE (halobiid clams)


On-Site Images From The Middle Triassic Prida Formation


Freshwater Mollusks From The Sehoo Formation, Nevada

Upper Pleistocene (24 To 13 Thousand Years Old)

Whenever I visit the incomparable ammonoid-bearing outcrops of the Middle Triassic Prida Formation, I like to stop off along the way, in Nevada, to hike and fossil-hunt amidst the great badlands deposits of the Upper Pleistocene Sehoo Formation. The Sehoo is roughly 24,000 to 13,000 years old and bears locally plentiful perfectly preserved fossil freshwater gastropods and pelecypods that lived in and around a pluvial lake (created primarily from rainfall) during a particularly wet and cool interglacial period of the late Pleistocene epoch--an interval that, on a world-wide level, geologists believe was fully 2.5 degrees Celsius colder, 65 percent wetter, and experienced 10 percent less evaporation than at present. The Sehoo pluvial system, as a matter of fact, was one of the last great freshwater lakes that existed in late Pleistocene times in what is today the arid Great Basin--a vast body of water that at its highest stand was some 1,330 feet deep (modern-day Lake Tahoe in the Sierra Nevada, by the way, is 1,900 feet deep).

  • Pelecypods: Genus Pisidium Common Name--Peaclam

  • Pelecypods: Genus Pisidium Common Name--Peaclam

  • Pelecypod: Genus Anodonta Common Name--Fat Floater

  • Gastropods: Genus Physa Common Name--Obtuse Physa

  • Gastropod: Genus Stagnicola Common Name--Pondsnail

  • Gastropods: Genus Valvata Common Name--Valve Snail

  • Gastropopds: Genus Planorbis Common Name--Ram's-Horn

On-Site Images Of The Sehoo Formation, Nevada

Upper Pleistocene (24 to 13 Thousand Years Old)

Links To The Triassic Period

Explore The Geologic Interval 248 To 206 Million Years Ago

Ammonoid Links

Places In Cyberspace That Pertain To Ammonoids

Everyone's Invited To Visit My Other Web Sites

Music-Related 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.
  • 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.
  • 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).
  • 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.
  • 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.
  • 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.
  • 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.
  • 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.
  • 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.
  • 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.
  • 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 240 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.
  • Fossils From The Savage Canyon Formation, Nevada: Images of fossil plants and an insect from a classic Middle Miocene geologic rock formation in Nevada.
  • 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.

United States Geological Survey Papers (Public Domain)

Online versions of USGS publications

 Images Of Prida Fm. Fossils  Images Of Prida Fm. Ammonoids  Images Of Prida Fm. Fossils In Matrix
On-Site Prida Fm. Images Images Of Sehoo Fm. Mollusks On-Site Sehoo Fm. Images
Ammonoids Geologic History Links To The Triassic Period Links To Ammonoids
BLM Rules For Fossil Collecting My Other Web Pages My Email Address

Return To Fossils In Death Valley National Park