"Rauisuchia" is a paraphyletic group of mostly large and carnivorous Triassic archosaurs. Rauisuchians are a category of archosaurs within a larger group called Pseudosuchia, which encompasses all archosaurs more closely related to crocodilians than to birds and other dinosaurs. First named in the 1940s, Rauisuchia was a name exclusive to Triassic archosaurs which were generally large, carnivorous, and quadrupedal with a pillar-erect hip posture, though exceptions exist for all of these traits. Rauisuchians, as a traditional taxonomic group, were considered distinct from other Triassic archosaur groups such as early dinosaurs, phytosaurs, aetosaurs, and crocodylomorphs.
Postosuchus, meaning "Crocodile from Post", is an extinct genus of rauisuchid reptiles comprising two species, P. kirkpatricki and P. alisonae, that lived in what is now North America during the Late Triassic. Postosuchus is a member of the clade Pseudosuchia, the lineage of archosaurs that includes modern crocodilians. Its name refers to Post Quarry, a place in Texas where many fossils of the type species, P. kirkpatricki, were found. It was one of the apex predators of its area during the Triassic, larger than the small dinosaur predators of its time. It was a hunter which probably preyed on large bulky herbivores like dicynodonts and many other creatures smaller than itself.
Effigia was an extinct genus of shuvosaurid known from the Late Triassic of New Mexico, south-western USA. With a bipedal stance, long neck, and a toothless beaked skull, Effigia and other shuvosaurids bore a resemblance to the ornithomimid dinosaurs of the Cretaceous Period. However, shuvosaurids were not dinosaurs, but were instead a specialized family of poposauroid pseudosuchians, meaning that their closest living relatives are crocodilians.
Marasuchus is a genus of basal dinosauriform archosaur which is possibly synonymous with Lagosuchus. Both genera lived during the Late Triassic in what is now La Rioja Province, Argentina. Marasuchus contains a single species, Marasuchus lilloensis.
Gracilisuchus is an extinct genus of tiny pseudosuchian from the Late Triassic of Argentina. It contains a single species, G. stipanicicorum, which is placed in the clade Suchia, close to the ancestry of crocodylomorphs. Both the genus and the species were first described by Alfred Romer in 1972.
Riojasuchus is an extinct genus of ornithosuchid archosaur from the Late Triassic (Norian) of Argentina. Ornithosuchidae was a widespread family of facultatively bipedal pseudosuchians with adaptations for scavenging. Riojasuchus is notable as one of the youngest and most complete members of the family. The type and only known species, Riojasuchus tenuisceps, was named and described by José Bonaparte in 1967. It was one of the first of many well-preserved Triassic archosaurs to be discovered in Argentina. The holotype specimen, PVL 3827, was found in the Los Colorados Formation of the Ischigualasto-Villa Unión Basin in northwestern Argentina.
Lewisuchus is a genus of archosaur that lived during the Late Triassic. As a silesaurid dinosauriform, it was a member of the group of reptiles most commonly considered to be the closest relatives of dinosaurs. Lewisuchus was about 1 metre (3.3 ft) long. Fossils have been found in the Chañares Formation of Argentina. It exhibited osteoderms along its back.
Poposaurus is an extinct genus of pseudosuchian archosaur from the Late Triassic of the southwestern United States. It belongs to the clade Poposauroidea, an unusual group of Triassic pseudosuchians that includes sail-backed, beaked, and aquatic forms. Fossils have been found in Wyoming, Utah, Arizona, and Texas. Except for the skull, most parts of the skeleton are known. The type species, P. gracilis, was described and named by Maurice Goldsmith Mehl in 1915. A second species, P. langstoni, was originally the type species of the genus Lythrosuchus. Since it was first described, Poposaurus has been variously classified as a dinosaur, a phytosaur, and a "rauisuchian".
Saurosuchus is an extinct genus of large loricatan pseudosuchian archosaurs that lived in South America during the Late Triassic period. It was a heavy, ground-dwelling, quadrupedal carnivore, likely being the apex predator in the Ischigualasto Formation.
Prestosuchus is an extinct genus of pseudosuchian in the group Loricata, which also includes Saurosuchus and Postosuchus. It has historically been referred to as a "rauisuchian", and was the defining member of the family Prestosuchidae, though the validity of both of these groups is questionable: Rauisuchia is now considered paraphyletic and Prestosuchidae is polyphyletic in its widest form.
Yarasuchus is an extinct genus of avemetatarsalian archosaur that lived during the Anisian stage of the Middle Triassic of India. The genus was named and described in 2005 from a collection of disarticulated but fairly complete fossil material found from the Middle Triassic Yerrapalli Formation. The material is thought to be from two individuals, possibly three, with one being much more complete and articulated than the other. The type and only species is Y. deccanensis. Yarasuchus was a quadruped roughly 2–2.5 metres (6.6–8.2 ft) long, with an elongated neck and tall spines on its vertebrae. Unlike other quadrupedal Triassic reptiles, the limbs and shoulders of Yarasuchus were slender, and more like those of ornithodirans.
Arganasuchus is an extinct genus of "rauisuchian" (loricatan) archosaur. It is known from a single species, Arganasuchus dutuiti. Fossils of this genus have been found in Upper Triassic rocks of the Argana Basin, Morocco. Though its remains were initially referred to Ticinosuchus when discovered during the 1970s, in 2007 it was identified as a distinct genus with unique features of the pubis and maxilla. Arganasuchus also had several anatomical details in common with Batrachotomus, Fasolasuchus, and Postosuchus, though its relations with other loricatans remains unresolved. Arganasuchus is considered a carnivore due to its large, knife-shaped teeth.
Mandasuchus is an extinct genus of loricatan pseudosuchian from the Manda Formation of Tanzania, which dates back to the Anisian stage of the Middle Triassic. Although this genus was first mentioned by Alan Charig in 1956, a formal description was not published until 2018.
Loricata is a clade of archosaur reptiles that includes crocodilians and some of their Triassic relatives, such as Postosuchus and Prestosuchus. More specifically, Loricata includes Crocodylomorpha and most "rauisuchians", a paraphyletic grade of large terrestrial pseudosuchians which were alive in the Triassic period and ancestral to crocodylomorphs.
Poposauroidea is a clade of advanced pseudosuchians. It includes poposaurids, shuvosaurids, ctenosauriscids, and other unusual pseudosuchians such as Qianosuchus and Lotosaurus. It excludes most large predatory quadrupedal "rauisuchians" such as rauisuchids and "prestosuchids". Those reptiles are now allied with crocodylomorphs in a clade known as Loricata, which is the sister taxon to the poposauroids in the clade Paracrocodylomorpha. Although it was first formally defined in 2007, the name "Poposauroidea" has been used for many years. The group has been referred to as Poposauridae by some authors, although this name is often used more narrowly to refer to the family that includes Poposaurus and its close relatives.
Paracrocodylomorpha is a clade of pseudosuchian archosaurs. The clade includes the diverse and unusual group Poposauroidea as well as the generally carnivorous and quadrupedal members of Loricata, including modern crocodylians. Paracrocodylomorpha was named by paleontologist J. Michael Parrish in 1993, although the group is now considered to encompass more reptiles than his original definition intended. The most recent definition of Paracrocodylomorpha, as defined by Sterling Nesbitt in 2011, is "the least inclusive clade containing Poposaurus and Crocodylus niloticus. Most groups of paracrocodylomorphs became extinct at the end of the Triassic period, with the exception of the crocodylomorphs, from which crocodylians such as crocodiles and alligators evolved in the latter part of the Mesozoic.
Xilousuchus is an extinct genus of poposauroid from lower Triassic deposits of Fugu County of northeastern Shanxi Province, China. It is known from the holotype, IVPP V 6026, a single well-preserved partial skeleton including the skull. It was found from the Heshanggou Formation of the Ordos Basin, Hazhen commune. It was first named by Xiao-Chun Wu in 1981 and the type species is Xilousuchus sapingensis. Wu (1981) referred Xilousuchus to the Proterosuchia. Gower and Sennikov (1996) found it to be an erythrosuchian based strictly on the braincase. A more detailed re-description of the genus was provided by Nesbitt et al. (2010) and found poposauroid affinities. In his massive revision of archosaurs which included a large cladistic analysis, Sterling J. Nesbitt (2011) found Xilousuchus to be a poposauroid which is most closely related to Arizonasaurus. Xilousuchus is the oldest archosaur to date, although Ctenosauriscus and Vytshegdosuchus might be even older by less than one million year. Since Xilousuchus is a suchian archosaur, its early age suggests that most of the major groups of archosaurs developed by the Early Triassic, soon after the appearance of the first archosaur.
Diandongosuchus is an extinct genus of archosauriform reptile, possibly a member of the Phytosauria, known from the Middle Triassic of China. The type species Diandongosuchus fuyuanensis was named in 2012 from the Zhuganpo Formation of Yunnan Province. It is a marine species that shows similarities with another Chinese Triassic species called Qianosuchus mixtus, although it has fewer adaptations toward marine life. It was originally classified as the basal-most member of the pseudosuchian clade Poposauroidea. However, a subsequent study conducted by Stocker et al. indicated it to be the basalmost known phytosaur instead.
Aphanosauria is an extinct group of reptiles distantly related to dinosaurs. They are at the base of a group known as Avemetatarsalia, one of two main branches of archosaurs. The other main branch, Pseudosuchia, includes modern crocodilians. Aphanosaurs possessed features from both groups, indicating that they are the oldest and most primitive known clade of avemetatarsalians, at least in terms of their position on the archosaur family tree. Other avemetatarsalians include the flying pterosaurs, small bipedal lagerpetids, herbivorous silesaurids, and the incredibly diverse dinosaurs, which survive to the present day in the form of birds. Aphanosauria is formally defined as the most inclusive clade containing Teleocrater rhadinus and Yarasuchus deccanensis but not Passer domesticus or Crocodylus niloticus. This group was first recognized during the description of Teleocrater. Although only known by a few genera, Aphanosaurs had a widespread distribution across Pangaea in the Middle Triassic. They were fairly slow quadrupedal long-necked carnivores, a biology more similar to basal archosaurs than to advanced avemetatarsalians such as pterosaurs, lagerpetids, and early dinosaurs. In addition, they seemingly possess 'crocodile-normal' ankles, showing that 'advanced mesotarsal' ankles were not basal to the whole clade of Avemetatarsalia. Nevertheless, they possessed elevated growth rates compared to their contemporaries, indicating that they grew quickly, more like birds than other modern reptiles. Despite superficially resembling lizards, the closest modern relatives of aphanosaurs are birds.
Incertovenator is an extinct genus of archosauriform reptile, likely an archosaur, of uncertain affinities. Its unstable position is a result of possessing a number features found in both the bird-line avemetatarsalian archosaurs and the crocodylian-line pseudosuchians. The type and only known species is I. longicollum, which is known from single specimen discovered in the Late Triassic Ischigualasto Formation of Argentina. Incertovenator is known almost entirely by its vertebral column. This indicates that it had a relatively long neck, leading to its uncertain classification due to the convergent evolution of elongated neck vertebrae in both avemetatarsalian and pseudosuchian archosaurs.
