Coelophysis is an extinct genus of coelophysid theropod dinosaur that lived approximately 228 to 200 million years ago during the latter part of the Triassic Period from the Carnian and Rhaetian faunal stages in what is now the southwestern United States; a specimen possibly belonging to the second species, C. rhodesiensis, has been found in South Africa and Zimbabwe, though this interpretation has been challenged since 2017.
Aetosaurs were heavily armored reptiles belonging to the extinct order Aetosauria. They were medium- to large-sized omnivorous or herbivorous pseudosuchians, part of the branch of archosaurs more closely related to crocodilians than to birds and other dinosaurs. All known aetosaurs are restricted to the Late Triassic, and in some strata from this time they are among the most abundant fossil vertebrates. They have small heads, upturned snouts, erect limbs, and a body ornamented with four rows of plate-like osteoderms. Aetosaur fossil remains are known from Europe, North and South America, parts of Africa, and India. Since their armoured plates are often preserved and are abundant in certain localities, aetosaurs serve as important Late Triassic tetrapod index fossils. Many aetosaurs had wide geographic ranges, but their stratigraphic ranges were relatively short. Therefore, the presence of particular aetosaurs can accurately date a site that they are found in.
Coelophysidae is a family of primitive carnivorous theropod dinosaurs. Most species were relatively small in size. The family flourished in the Late Triassic and Early Jurassic periods, and has been found on numerous continents. Many members of Coelophysidae are characterized by long, slender skulls and light skeletons built for speed. One member, Coelophysis, displays the earliest known furcula in a dinosaur.
The Chinle Formation is an Upper Triassic continental geological formation of fluvial, lacustrine, and palustrine to eolian deposits spread across the U.S. states of Nevada, Utah, northern Arizona, western New Mexico, and western Colorado. In New Mexico, it is often raised to the status of a geological group, the Chinle Group. Some authors have controversially considered the Chinle to be synonymous to the Dockum Group of eastern Colorado and New Mexico, western Texas, the Oklahoma panhandle, and southwestern Kansas. The Chinle Formation is part of the Colorado Plateau, Basin and Range, and the southern section of the Interior Plains. A probable separate depositional basin within the Chinle is found in northwestern Colorado and northeastern Utah. The southern portion of the Chinle reaches a maximum thickness of a little over 520 meters (1,710 ft). Typically, the Chinle rests unconformably on the Moenkopi Formation.
Rhynchosaurs are a group of extinct herbivorous Triassic archosauromorph reptiles, belonging to the order Rhynchosauria. Members of the group are distinguished by their triangular skulls and elongated, beak like premaxillary bones. Rhynchosaurs first appeared in the Middle Triassic or possibly the Early Triassic, before becoming abundant and globally distributed during the Carnian stage of the Late Triassic.
Spinosuchus is an extinct genus of trilophosaurid allokotosaur from the Late Triassic of Texas, southern United States. It has been assigned to a variety of groups over its history, from coelophysid dinosaur to pseudosuchian to uncertain theropod dinosaur and to Proterosuchidae. This uncertainty is not unusual, given that it was only known from a poorly preserved, wall-mounted, partial vertebral column of an animal that lived in a time of diverse, poorly known reptile groups. However, newly collected material and recent phylogenetic studies of early archosauromorphs suggest that it represents an advanced trilophosaurid very closely related to Trilophosaurus.
Dromomeron is a genus of lagerpetid avemetatarsalian which lived around 220 to 211.9 ± 0.7 million years ago. The genus contains species known from Late Triassic-age rocks of the Southwestern United States and northwestern Argentina. It is described as most closely related to the earlier Lagerpeton of Argentina, but was found among remains of true dinosaurs like Chindesaurus, indicating that the first dinosaurs did not immediately replace related groups.
Redondasaurus is an extinct genus of phytosaur from the Late Triassic of the southwestern United States. It was named by Hunt & Lucas in 1993, and contains two species, R. gregorii and R. bermani. It is the youngest and most evolutionarily-advanced of the phytosaurs.
Typothorax is an extinct genus of typothoracine aetosaur that lived in the Late Triassic. Its remains have been found in North America. Two species are known: T. coccinarum, the type species, and T. antiquum.
Arganodus is an extinct genus of Ceratodontidae (lungfish). Its fossils have been found in the Redonda Formation, New Mexico, the Tacuarembó Formation of Uruguay, and the Cumnock Formation, North Carolina, although the North Carolinian specimens are smaller than most recorded specimens. Fossils have also been uncovered in the Petrified Forest National Park. It was first named by Martin in 1979, and contains two species, A. dorotheae and A. atlantis. Arganodus was probably similar to modern lungfish, and lived in underwater burrows during dry periods until monsoons occurred.
Metoposauridae is an extinct family of trematosaurian temnospondyls. The family is known from the Triassic period. Most members are large, approximately 1.5 metres (4.9 ft) long and could reach 3 m long. Metoposaurids can be distinguished from the very similar mastodonsauroids by the position of their eyes, placed far forward on the snout.
Adamanasuchus is an extinct genus of aetosaur. Fossils have been found from several localities from the Chinle Group in Arizona and date back to the late Carnian stage of the Late Triassic. The locality from which it was named after also lends its name to the Adamanian LVF.
Anaschisma is an extinct genus of large temnospondyl amphibians. These animals were part of the family called Metoposauridae, which filled the crocodile-like predatory niches in the late Triassic. It had large skull about 62 centimetres (24 in) long, and possibly reached 3 metres (9.8 ft) long. It was an ambush hunter, snapping up anything small enough to fit in its huge jaws. It was very common during the Late Triassic in what is now the American Southwest.
Rioarribasuchus is a genus of aetosaur. Fossils have been found from the Chinle Formation in Arizona and New Mexico that date back to the upper Late Carnian stage of the Late Triassic.
Cuyosuchus is an extinct genus of archosauriform reptile. Its fossils have been found in Late Triassic-aged rocks of the Cacheuta Formation, Cuyo Basin, Mendoza, Argentina. Cuyosuchus is based on MCNAM 2669, a partial postcranial skeleton including 26 vertebrae from all parts of the spinal column, ribs, partial pectoral girdles, part of the pelvis, upper arms and part of the lower arms, the left thigh bone and shin, pitted armor scutes, and fragments. It was described in 1961 by Osvaldo Reig and named after the Cuyo Basin; the type species is C. huenei, referring to German paleontologist Friedrich von Huene. Although originally described as a proterosuchid, restudy by Julia Desojo and colleagues in 2003 found that it could not be assigned to any family.
Leptosuchus is an extinct genus of leptosuchomorph phytosaur with a complex taxonomical history. Fossils have been found from the Dockum Group and lower Chinle Formation outcropping in Texas, New Mexico, and Arizona, USA, and date back to the Carnian stage of the Late Triassic.
Parrishia is an extinct genus of sphenosuchian crocodylomorph known from the Late Triassic Chinle, Dockum, and Santa Rosa Formations in Arizona and New Mexico.
Protorosauria is an extinct polyphyletic group of archosauromorph reptiles from the late Permian to the start of the Late Triassic of Asia, Europe, North America. It was named by the English anatomist and paleontologist Thomas Henry Huxley in 1871 as an order, originally to solely contain Protorosaurus. Other names which were once considered equivalent to Protorosauria include Prolacertiformes and Prolacertilia.
Tanytrachelos is an extinct genus of tanystropheid archosauromorph reptile from the Late Triassic of the eastern United States. It contains a single species, Tanytrachelos ahynis, which is known from several hundred fossil specimens preserved in the Solite Quarry in Cascade, Virginia. Abundant fossils of Tanytrachelos are found in a series of lakebed sediments that were deposited over the course of about 350 thousand years in a lake which existed approximately 230 million years ago. Some fossils are very well-preserved and include the remains of soft tissues. Tanytrachelos is the most likely trackmaker of the ichnogenus Gwyneddichnium.
Ankylosuchus is an extinct doswelliid archosauromorph reptile from the Late Triassic of Texas. Ankylosuchus is a monotypic genus and the type species is Ankylosuchus chinlegroupensis. It was named in 2013 on the basis of a fossil specimen including fragments of four vertebrae, parts of the skull, and part of a limb bone. These remains come from the Colorado City Formation, which dates to the early Carnian age of the Late Triassic. A. chinlegroupensis is named after the Chinle Group, a stratigraphic group that many Late Triassic formations of the southwestern United States have often been placed under, although a recent revision in stratigraphic nomenclature favors it being called the Dockum Group, which would make the species name a misnomer. Ankylosuchus is similar to other doswelliids in having heavy armor consisting of thick bony plates called osteoderms that interlock tightly and are irregularly pitted. It differs from other doswelliids in that the pits on the osteoderms are deeper and some osteoderms are fused to those that lie laterally to them.
