| Favret Formation | |
|---|---|
| Stratigraphic range: Triassic | |
| Type | Geological formation |
| Unit of | Augusta Sequence |
| Lithology | |
| Primary | Limestone |
| Other | Shale, siltstone |
| Location | |
| Region | Nevada |
The Favret Formation is a Triassic geologic formation. The Favret outcrops in the Augusta, New Pass and Fish Creek ranges of north central Nevada and consists of limestone, shale and siltstone. [1]
The Favret Formation along with the Prida Formation, constitute one of the recognized geological formations within the Star Peak Group of northwestern Nevada. These two formations are linked by a single member, known as the Fossil Hill Member. In the Prida Formation, this member outcrops in the western Humboldt Range, while the Favret Formation, outcrops in the Augusta Mountains, where it reaches up to more than 300 metres (980 ft) thick. Although they overlap substantially, the two formations do not share precisely the same age, the Prida unit dates from the Middle to Late Anisian, while the Favret unit dates only from the Late Anisian, between approximately 244 and 242 million years ago. [2]
The Fossil Hill Member has received extensive interest from paleontological research for its large quantity of marine fossils dating from the Middle Triassic. The environment preserved in the Fossil Hill contains some of the earliest marine reptile communities including Ichthyosaurs and Pistosaurs. Other fossils from this unit include invertebrates such as ceratitid ammonoids and bivalves as well as hybodont sharks and bony fish like Saurichthyes and Birgeria.
In the geologic timescale, the Anisian is the lower stage or earliest age of the Middle Triassic series or epoch and lasted from 247.2 million years ago until 242 million years ago. The Anisian Age succeeds the Olenekian Age and precedes the Ladinian Age.
Cymbospondylus is an extinct genus of large ichthyosaurs, of which it is among the oldest representatives, that lived from the Lower to Middle Triassic in what are now North America and Europe. The first known fossils of this taxon are a set of more or less complete vertebrae which were discovered in the 19th century in various mountain ranges of Nevada, in the United States, before being named and described by Joseph Leidy in 1868. It is in the beginning of the 20th century that more complete fossils were discovered through several expeditions launched by the University of California, and described in more detail by John Campbell Merriam in 1908, thus visualizing the overall anatomy of the animal. While many species have been assigned to the genus, only five are recognized as valid, the others being considered synonymous, doubtful or belonging to other genera. Cymbospondylus was formerly classified as a representative of the Shastasauridae, but more recent studies consider it to be more basal, view as the type genus of the Cymbospondylidae.
The Cynognathus Assemblage Zone is a tetrapod biozone utilized in the Karoo Basin of South Africa. It is equivalent to the Burgersdorp Formation, the youngest lithostratigraphic formation in the Beaufort Group, which is part of the fossiliferous and geologically important Karoo Supergroup. The Cynognathus Assemblage Zone is the youngest of the eight biozones found in the Beaufort Group, and is considered to be late Early Triassic (Olenekian) to early Middle Triassic (Anisian) in age. The name of the biozone refers to Cynognathus crateronotus, a large and carnivorous cynodont therapsid which occurs throughout the entire biozone.
Omphalosaurus is an extinct genus of marine reptile from the Early Triassic to Middle Triassic, thought to be in the order of Ichthyosauria. Most of what is known about Omphalosaurus is based on multiple jaw fragments, ribs, and vertebrae. Specimens of Omphalosaurus have been described from the western United States, Poland, Austria and the island of Spitsbergen off the northern coast of Norway.
Birgeria is a genus of carnivorous marine ray-finned fish from the Triassic period. Birgeria had a global distribution, with fossil known from Madagascar, Spitsbergen, Germany, Switzerland, Italy, Slovenia, China, Russia, Canada and Nevada, United States. The oldest fossils are from Griesbachian aged beds of the Wordie Creek Formation of East Greenland. Birgeria existed throughout the entire Triassic period, from the very beginning just after the Permian-Triassic mass extinction, up to the very end with its extinction during the Triassic-Jurassic mass extinction.
Augustasaurus is an extinct genus of sauropterygians that lived during the Anisian stage of the Middle Triassic in what is now North America. Only one species is known, A. hagdorni, described in 1997 from fossils discovered in the Favret Formation, Nevada, USA.
Pteronisculus is an extinct genus of prehistoric ray-finned fish that lived during the Early Triassic and Middle Triassic epochs of the Triassic period worldwide.
Crenilepis is an extinct genus of prehistoric marine ray-finned fish that lived in the seas of present-day Europe during the Middle Triassic epoch. It contains a single species, C. sandbergi from the Anisian of Germany, Spain, and the Besano Formation of the Swiss-Italian border.
Luganoia is an extinct genus of prehistoric bony fish that lived during the Anisian and Ladinian ages of the Middle Triassic epoch. Fossils were recovered from the Besano Formation of Monte San Giorgio and Besano area and from the Zhuganpo Member of Guizhou, South China. It was also reported from the Ladinian of Spain.
Besania is an extinct genus of prehistoric marine ray-finned fish that lived during the Anisian and Ladinian ages of the Middle Triassic epoch in what is now southern/southeastern Switzerland and northern Italy. Fossils were recovered from the Besano Formation of Monte San Giorgio area and the Prosanto Formation of canton Graubünden, Switzerland.
Ctenognathichthys is an extinct genus of prehistoric marine ray-finned fish that lived during the Middle Triassic epoch of Europe, in the former Tethys Ocean.
Meridensia is an extinct genus of prehistoric ray-finned fish that lived during the Anisian and Ladinian ages of the Middle Triassic epoch in what is now southern Switzerland and northern Italy. Fossils were recovered from the Besano Formation of Monte San Giorgio and Besano area at the Swiss-Italian boundary.
The Liard Formation is a stratigraphic unit of Middle Triassic to Late Triassic age in the Western Canadian Sedimentary Basin that is present in northeastern British Columbia. It takes its name from the Liard River, and was first described from outcrops on the southern bank of that river, near Hell Gate Rapids in the Grand Canyon of the Liard, by E.D. Kindle in 1946.
The Mercia Mudstone Group is an early Triassic lithostratigraphic group which is widespread in Britain, especially in the English Midlands—the name is derived from the ancient kingdom of Mercia which corresponds to that area. It is frequently encountered in older literature as the Keuper Marl or Keuper Marl Series.
Paleontology in Nevada refers to paleontological research occurring within or conducted by people from the U.S. state of Nevada. Nevada has a rich fossil record of plants and animal life spanning the past 650 million years of time. The earliest fossils from the state are from Esmeralda County, and are Late Proterozoic in age and represent stromatolite reefs of cyanobacteria, amongst these reefs were some of the oldest known shells in the fossil record, the Cloudina-fauna. Much of the Proterozoic and Paleozoic fossil story of Nevada is that of a warm, shallow, tropical sea, with a few exceptions towards the Late Paleozoic. As such, many fossils across the state are those of marine animals, such as trilobites, brachiopods, bryozoans, honeycomb corals, archaeocyaths, and horn corals.
Thalattoarchon is a genus of large, Middle Triassic predatory ichthyosaur from North America, containing the single species T. saurophagis. The taxon was described in 2013 from a single specimen discovered in the Favret Formation in Nevada. The generic name, meaning "ruler of the seas", refers to its status as an apex predator, while the specific epithet, meaning "lizard eater", alludes to its carnivorous diet. The classification of this genus within the ichthyosaurs is much debated, being either classified within the clade Merriamosauria or in the more basal family Cymbospondylidae.
The Prida Formation is a geologic formation in northwestern Nevada. It preserves fossils dating back to the Triassic period.
The Candelaria Formation is a geologic formation in Nevada, United States. The formation comprises shales and limestones deposited in an open marine environment and preserves fossils dating back to the Induan age of the Early Triassic epoch. Outcrops of the Candelaria Formation are present in the Candelaria Hills southeast of the now abandoned mining town of Candelaria, and near Willow Springs.
The Wordie Creek Formation is an uppermost Permian and Lower Triassic geologic formation in Greenland, outcrops of which are located in Northeast Greenland National Park. In 2017, it was suggested to be raised to group status, as the Wordie Creek Group.
The Röt Formation or Rötton Formation, or Upper Buntsandstein, is a geologic formation of the Buntsandstein in Germany. It preserves fossils dating back to the Middle Triassic Epoch. The formation overlies the Plattenstein and Solling Formations and is overlain by the Jena Formation.
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