Lagosuchus is an extinct genus of avemetatarsalian archosaur from the Late Triassic of Argentina. The type species of Lagosuchus, Lagosuchus talampayensis, is based on a small partial skeleton recovered from the early Carnian-age Chañares Formation. The holotype skeleton of L. talampayensis is fairly fragmentary, but it does possess some traits suggesting that Lagosuchus was a probable dinosauriform, closely related to dinosaurs.
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.
Lagerpeton is a genus of lagerpetid avemetatarsalian, comprising a single species, L. chanarensis. First described from the Chañares Formation of Argentina by A. S. Romer in 1971, Lagerpeton's anatomy is somewhat incompletely known, with fossil specimens accounting for the pelvic girdle, hindlimbs, posterior presacral, sacral and anterior caudal vertebrae. Skull and shoulder material has also been described.
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.
Teleocrater is a genus of avemetatarsalian archosaur from the Middle Triassic Manda Formation of Tanzania. The name was coined by English paleontologist Alan Charig in his 1956 doctoral dissertation, but was only formally published in 2017 by Sterling Nesbitt and colleagues. The genus contains the type and only species T. rhadinus. Uncertainty over the affinities of Teleocrater have persisted since Charig's initial publication; they were not resolved until Nesbitt et al. performed a phylogenetic analysis. They found that Teleocrater is most closely related to the similarly enigmatic Yarasuchus, Dongusuchus, and Spondylosoma in a group that was named the Aphanosauria. Aphanosauria was found to be the sister group of the Ornithodira, the group containing dinosaurs and pterosaurs.
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".
Dinosauromorpha is a clade of avemetatarsalians that includes the Dinosauria (dinosaurs) and some of their close relatives. It was originally defined to include dinosauriforms and lagerpetids, with later formulations specifically excluding pterosaurs from the group. Birds are the only dinosauromorphs which survive to the present day.
Turfanosuchus is a genus of archosauriform reptile, likely a gracilisuchid archosaur, which lived during the Middle Triassic (Anisian) of northwestern China. The type species, T. dabanensis, was described by C.C. Young in 1973, based on a partially complete but disarticulated fossil skeleton found in the Kelamayi Formation of the Turfan Basin.
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.
Chanaresuchus is an extinct genus of proterochampsid archosauriform. It was of modest size for a proterochampsian, being on average just over a meter in length. The type species is Chanaresuchus bonapartei was named in 1971. Its fossils were found in from the early Carnian-age Chañares Formation in La Rioja Province, Argentina. Chanaresuchus appears to be one of the most common archosauriforms from the Chañares Formation due to the abundance of specimens referred to the genus. Much of the material has been found by the La Plata-Harvard expedition of 1964-65. Chanaresuchus is the most well-described proterochampsid in the subfamily Rhadinosuchinae.
The Chañares Formation is a Carnian-age geologic formation of the Ischigualasto-Villa Unión Basin, located in La Rioja Province, Argentina. It is characterized by drab-colored fine-grained volcaniclastic claystones, siltstones, and sandstones which were deposited in a fluvial to lacustrine environment. The formation is most prominently exposed within Talampaya National Park, a UNESCO World Heritage Site within La Rioja Province.
Vancleavea is a genus of extinct, armoured, non-archosaurian archosauriforms from the Late Triassic of western North America. The type and only known species is V. campi, named by Robert Long & Phillip A Murry in 1995. At that time, the genus was only known from fragmentary bones including osteoderms and vertebrae. However, since then many more fossils have been found, including a pair of nearly complete skeletons discovered in 2002. These finds have shown that members of the genus were bizarre semiaquatic reptiles. Vancleavea individuals had short snouts with large, fang-like teeth, and long bodies with small limbs. They were completely covered with bony plates known as osteoderms, which came in several different varieties distributed around the body. Phylogenetic analyses by professional paleontologists have shown that Vancleavea was an archosauriform, part of the lineage of reptiles that would lead to archosaurs such as dinosaurs and crocodilians. Vancleavea lacks certain traits which are present in most other archosauriforms, most notably the antorbital, mandibular and supratemporal fenestrae, which are weight-saving holes in the skulls of other taxa. However, other features clearly support its archosauriform identity, including a lack of intercentra, the presence of osteoderms, an ossified laterosphenoid, and several adaptations of the femur and ankle bones. In 2016, a new genus of archosauriform, Litorosuchus, was described. This genus resembled both Vancleavea and more typical archosauriforms in different respects, allowing Litorosuchus to act as a transitional fossil linking Vancleavea to less aberrant archosauriforms.
Lagerpetidae is a family of basal avemetatarsalians. Though traditionally considered the earliest-diverging dinosauromorphs, fossils described in 2020 suggest that lagerpetids may instead be pterosauromorphs. Lagerpetid fossils are known from theTriassic of Argentina, Arizona, Brazil, Madagascar, New Mexico, and Texas. They were typically small, although some lagerpetids, like Dromomeron gigas and a specimen from the Santa Rosa Formation attributed to Dromomeron sp., were able to get quite large. Lagerpetid fossils are rare; the most common finds are bones of the hindlimbs, which possessed a number of unique features.
Tarjadia is an extinct genus of erpetosuchid pseudosuchian, distantly related to modern crocodilians. It is known from a single species, T. ruthae, first described in 1998 from the Middle Triassic Chañares Formation in Argentina. Partial remains have been found from deposits that are Anisian-Ladinian in age. Long known mostly from osteoderms, vertebrae, and fragments of the skull, specimens described in 2017 provided much more anatomical details and showed that it was a fairly large predator. Tarjadia predates known species of aetosaurs and phytosaurs, two Late Triassic groups of crurotarsans with heavy plating, making it one of the first heavily armored archosaurs. Prior to 2017, most studies placed it outside Archosauria as a member of Doswelliidae, a family of heavily armored and crocodile-like archosauriforms. The 2017 specimens instead show that it belonged to the Erpetosuchidae.
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.
Lutungutali is an extinct genus of silesaurid dinosauriform from the Middle Triassic of Zambia. The single type species of the genus is Lutungutali sitwensis. Lutungutali was named in 2013 and described from a fossil specimen, holotype NHCC LB32, including hip bones and tail vertebrae. The specimen was collected in 2009 from the upper Ntawere Formation, which dates to the Anisian stage of the Middle Triassic. Lutungutali is the first known silesaurid from Zambia and, along with the Tanzanian silesaurid Asilisaurus and dinosauriform Nyasasaurus, the oldest bird-line archosaur known from body fossils.
Ixalerpeton is a genus of lagerpetid avemetatarsalian containing one species, I. polesinensis. It lived in the Late Triassic of Brazil alongside the sauropodomorph dinosaur Buriolestes.
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.
Polymorphodon is an extinct genus of archosauriform reptile from the Middle Triassic of Germany. The only known species is Polymorphodon adorfi, discovered in Lower Keuper deposits at a quarry in Eschenau, Germany. Polymorphodon is notable for its heterodont dentition, with long and conical premaxillary teeth followed by thin maxillary teeth with large serrations. Maxillary teeth near the back of the mouth are short and leaf-shaped, similar to some living and extinct reptiles with a herbivorous or omnivorous diet. This may suggest that Polymorphodon had some reliance on plants in its diet, a rarity among basal archosauriforms, most of which are carnivores.
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.
