The Rhaetian is the latest age of the Triassic Period or the uppermost stage of the Triassic System. It was preceded by the Norian and succeeded by the Hettangian. The base of the Rhaetian lacks a formal GSSP, though candidate sections include Steinbergkogel in Austria and Pignola-Abriola in Italy. The end of the Rhaetian is more well-defined. According to the current ICS system, the Rhaetian ended 201.3 ± 0.2 Ma.
The Newark Supergroup, also known as the Newark Group, is an assemblage of Upper Triassic and Lower Jurassic sedimentary rocks which outcrop intermittently along the United States East Coast. They were deposited in a series of Triassic basins approximately 190 million years ago as North America separated from Africa. The exposures extend from Nova Scotia to North Carolina. Related basins are also found underwater in the Bay of Fundy. The group is named for the city of Newark, New Jersey.
Doswellia is an extinct genus of archosauriform from the Late Triassic of North America. It is the most notable member of the family Doswelliidae, related to the proterochampsids. Doswellia was a low and heavily built carnivore which lived during the Carnian stage of the Late Triassic. It possesses many unusual features including a wide, flattened head with narrow jaws and a box-like rib cage surrounded by many rows of bony plates. The type species Doswellia kaltenbachi was named in 1980 from fossils found within the Vinita member of the Doswell Formation in Virginia. The formation, which is found in the Taylorsville Basin, is part of the larger Newark Supergroup. Doswellia is named after Doswell, the town from which much of the taxon's remains have been found. A second species, D. sixmilensis, was described in 2012 from the Bluewater Creek Formation of the Chinle Group in New Mexico; however, this species was subsequently transferred to a separate doswelliid genus, Rugarhynchos. Bonafide Doswellia kaltenbachi fossils are also known from the Chinle Formation of Arizona.
The New Oxford Formation is a mapped bedrock unit consisting primarily of sandstones, conglomerates, and shales. The New Oxford Formation was first described in Adams County, Pennsylvania in 1929, and over the following decade was mapped in adjacent York County, Pennsylvania and Frederick County, Maryland. It was described as "red shale and sandstone with beds of micaceous sandstone, arkose, and conglomerate." The majority of this early mapping was done by George Willis Stose, Anna Isabel Jonas, and Florence Bascom.
The Pekin Formation is a Late Triassic (Carnian) geological formation in North Carolina. The Pekin Formation is specific to the Sanford Sub-Basin of the Deep River Basin of North Carolina, although it may be equivalent to the Stockton Formation of Pennsylvania, New Jersey, and New York. The Pekin Formation was deposited in a rift basin along the Atlantic margin of North America during the breakup of the supercontinent Pangaea during the Late Triassic. The most common rocks in the Pekin Formation are red to brown sandstones, representing a terrestrial fluvial (riverine) and floodplain environment in a hot, humid climate. It has yielded both abundant plant and animal fossils, including some of the oldest potential dinosaur footprints in the world and the large predatory crocodylomorph Carnufex carolinensis.
Euscolosuchus is an extinct genus of suchian closely related to crocodylomorphs. Fossils have been found from the Tomahawk Creek Member of the Turkey Branch Formation outcropping in east-central Virginia. The locality from which the material was found dates back to the early Carnian stage of the Late Triassic, based on palynological studies. These strata are known for the abundance of fossil material belonging to tetrapod vertebrates in relation to other sites of the Newark Supergroup in the Richmond Basin that generally lack such material. The site is unique among others in the supergroup and closely resembles localities in the southern hemisphere, as is suggested by the presence of numerous fossils of traversodont cynodonts found from the area. Other tetrapods present include procolophonians, chiniquodontids, and sphenodonts.
The Triassic Lockatong Formation is a mapped bedrock unit in Pennsylvania, New Jersey, and New York. It is named after the Lockatong Creek in Hunterdon County, New Jersey.
Stegomosuchus is an extinct genus of small protosuchian crocodylomorph. It is known from a single incomplete specimen discovered in the late 19th century in Lower Jurassic rocks of south-central Massachusetts, United States. It was originally thought to be a species of Stegomus, an aetosaur, but was eventually shown to be related to Protosuchus and thus closer to the ancestry of crocodilians. Stegomosuchus is also regarded as a candidate for the maker of at least some of the tracks named Batrachopus in the Connecticut River Valley.
The Cow Branch Formation is a Late Triassic geologic formation in the eastern United States. Indeterminate fossil ornithischian tracks have been reported from the formation.
Uatchitodon is an extinct genus of Late Triassic reptile known only from isolated teeth. Based on the structure of the teeth, Uatchitodon was probably a carnivorous archosauromorph. Folded grooves on the teeth indicate that the animal was likely venomous, with the grooves being channels for salivary venom. The teeth are similar to those of living venomous squamates such as Heloderma and venomous snakes. Uatchitodon is the earliest known venomous reptile.
The Gettysburg Formation is a mapped bedrock unit consisting primarily of sandstones, conglomerates, and shales.
The Taylorsville Basin is an early Mesozoic rift basin that either outcrops, or is present beneath younger deposits, in Virginia and Maryland. It is part of the chain of rift basins along the eastern part of North America that formed during the break-up of the Pangaea supercontinent. It is filled by a fluvial and lacustrine sedimentary sequence of the Newark Supergroup.
The Culpeper Basin is one of the Newark Supergroup's Triassic rift basins. It lies east of the Appalachian Mountains and extends from the Madison County—Orange County line in Virginia to Frederick, Maryland. A diverse group of sedimentary rocks including siltstone, sandstone, and congolmerate within the basin were intruded by igneous rocks, which caused thermal metamorphism at the contact with sedimentary rock.
The Bull Run Formation is a Late Triassic (Norian) stratigraphic unit in the eastern United States. Fossil fish bones and scales have been found in outcrops of the formation's Groveton Member in Manassas National Battlefield Park. Indeterminate fossil ornithischian tracks have been reported from the formation.
The Midland Formation is a Mesozoic geological formation in the Culpeper Basin of Virginia. It is a sedimentary unit which formed in a short period of time between the first two basalt flows in the basin: the Hickory Grove and Mount Zion Church basalts. The most common rocks in the formation are dark reddish interbedded sandstones and siltstones, representative of fluvial (stream) environments. Rare but fossiliferous calcareous shale and limestone also occurs, representing recurring lacustrine (lake) conditions. The Midland Formation is considered equivalent to the Shuttle Meadow Formation of the Hartford Basin, the Feltville Formation of the Newark Basin, and the Bendersville Formation of the Gettysburg Basin.
The Cumnock Formation is a Late Triassic-age geologic formation in North Carolina. It is found in the of the Sanford sub-basin of the Deep River Basin, the southernmost of the large Mesozoic basins forming the Newark Supergroup. It is the middle unit of the Chatham Group, overlying the Pekin Formation and underlying the Sanford Formation. Both of these encompassing formations are primarily red sandstone. The Cumnock Formation, on the other hand, represents a sequence of darker lacustrine (lake) or paludal (swampy/marshy) sediments deposited in a tropical climate. These primarily include shales and coal, with some thin layers of coarser sediment such as siltstone and sandstone.
The Chatham Group is a Triassic-age geologic group in the eastern United States. It is one of the most fossiliferous sections of the Newark Supergroup, preserving much of the Late Triassic up until the Triassic-Jurassic mass extinction. The group was originally named to refer to Triassic rocks specifically within the Deep River Basin of North Carolina. Later studies have utilized it to encompass Late Triassic strata in most other sedimentary basins in the Newark Supergroup.
Gwyneddichnium is an ichnogenus from the Late Triassic of North America and Europe. It represents a form of reptile footprints and trackways, likely produced by small tanystropheids such as Tanytrachelos. Gwyneddichnium includes a single species, Gwyneddichnium major. Two other proposed species, G. elongatum and G. minore, are indistinguishable from G. major apart from their smaller size and minor taphonomic discrepancies. As a result, they are considered junior synonyms of G. major.
The Sanford Formation is a Late Triassic (Norian)-age geologic formation in North Carolina. It is mainly found in the Sanford sub-basin of the Deep River Basin, the southernmost of the large Mesozoic basins forming the Newark Supergroup. It is the highest unit of the Chatham Group, overlying the dark lake and swamp sediments of the Cumnock Formation. The Sanford Formation is composed primarily of coarse red sediments such as conglomerates, sandstones, and mudstones. The conglomerate layers contain pebbles of schist and slate, with the occasional large boulders of granite.
The Catharpin Creek Formation is a Late Triassic geologic formation in Maryland and Virginia. It is found along the western edge of the Culpeper Basin, one of the largest sedimentary basins in the Newark Supergroup. Compared to the underlying Bull Run Formation, the Catharpin Creek Formation is dominated by much coarser sedimentary rocks such as sandstone and conglomerate. The base of the formation is reddish arkosic sandstone, which grades into drabber thin-bedded siltstone and shale in cyclical sequences.
