Archosauriformes is a clade of diapsid reptiles encompassing archosaurs and some of their close relatives. It was defined by Jacques Gauthier (1994) as the clade stemming from the last common ancestor of Proterosuchidae and Archosauria. Phil Senter (2005) defined it as the most exclusive clade containing Proterosuchus and Archosauria. Archosauriforms are a branch of archosauromorphs which originated in the Late Permian and persist to the present day as the two surviving archosaur groups: crocodilians and birds.
Chasmatosuchus was an archosauriform reptile from the early Triassic period of European Russia. One of the earliest described archosauriforms, it was over 2 m long and is thought to have behaved like a modern crocodile. Its mouth had two distinct features: the top of its jaw hooked downwards to aid in holding prey, and the upper palate was lined with a row of teeth—a primitive feature lost in later archosaurs.
Erythrosuchidae are a family of large basal archosauriform carnivores that lived from the later Early Triassic (Olenekian) to the early Middle Triassic (Anisian).
Proterosuchidae is an early family of basal archosauriforms whose fossils are known from the Late Permian and the Early Triassic. The highest diversity of genera is known from European Russia, but fossils are also known from South Africa, India, China, Australia, Brazil and possibly Argentina. The name comes from Greek πρότερο- ("first") and σοῦχος ("crocodile").
Proterosuchus is an extinct genus of archosauriform reptiles that lived during the Early Triassic. It contains three valid species: the type species P. fergusi and the referred species P. alexanderi and P. goweri. All three species lived in what is now South Africa. The genus was named in 1903 by the South African paleontologist Robert Broom. The genus Chasmatosaurus is a junior synonym of Proterosuchus.
Tasmaniosaurus is an extinct genus of archosauromorph reptile known from the Knocklofty Formation of West Hobart, Tasmania, Australia. The type species is T. triassicus. This genus is notable not only due to being one of the most complete Australian Triassic reptiles known, but also due to being a very close relative of Archosauriformes. Once believed to be a proterosuchid, this taxon is now believed to have been intermediate between advanced non-archosauriform archosauromorphs such as Prolacerta, and basal archosauriforms such as Proterosuchus. Features traditionally used to define Archosauria and later Archosauriformes, such as the presence of an antorbital fenestra and serrated teeth, are now known to have evolved prior to those groups due to their presence in Tasmaniosaurus.
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.
Archosaurus is an extinct genus of carnivorous proterosuchid archosauriform reptile. Its fossils are dated to the latest Permian of Russia and Poland, it is one of the earliest known archosauriforms. The type and only species is Archosaurus rossicus, known from several fragmentary specimens which cumulatively represent parts of the skull and cervical vertebrae. It would have been 3 metres (9.8 ft) long when fully grown.
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.
Fugusuchus is an extinct genus of archosauriform, probably the basal-most member of the family Erythrosuchidae. The genus is known from a single fossil from the middle Early Triassic Heshanggou Formation in Shanxi, China. The partial skeleton consists of an incomplete skull, parts of the right forelimb, and an intercentrum. The skeleton, known as GMB V 313, is currently in the Geological Museum of China in Beijing.
Koilamasuchus is an extinct genus of indeterminate archosauriform from the Triassic of Argentina. It is based on an external mold of a partial postcranial skeleton from the Quebrada de los Fósiles Formation. Due to its incomplete nature, the relationships of this reptile are difficult to establish. Originally described as a non-archosaur archosauriform, later studies tentatively considered it a doswelliid or a suchian archosaur.
Rhadinosuchus is an extinct genus of proterochampsian archosauriform reptile from the Late Triassic. It is known only from the type species Rhadinosuchus gracilis, reposited in Munich, Germany. The fossil includes an incomplete skull and fragments of post-cranial material. Hosffstetter (1955), Kuhn (1966), Reig (1970) and Bonaparte (1971) hypothesized it to be synonymous with Cerritosaurus, but other characteristics suggest it is closer to Chanaresuchus and Gualosuchus, while it is certainly different from Proterochampsa and Barberenachampsa. The small size indicates it is a young animal, making it hard to classify.
Youngosuchus is an extinct genus of archosaur from the Middle Triassic of China. The type species is Y. sinensis. Y. sinensis was first described in 1973 as a new species of the erythrosuchid Vjushkovia. In 1985, it was reassigned as its own genus of rauisuchid. A 1992 study supported the original classification of Youngosuchus sinensis as an erythrosuchid, but more recent studies classify it as a "rauisuchian"-grade loricatan archosaur completely unrelated to Vjushkovia, which is most likely a synonym of Garjainia.
Jesairosaurus is an extinct genus of early archosauromorph reptile known from the Illizi Province of Algeria. It is known from a single species, Jesairosaurus lehmani. Although a potential relative of the long-necked tanystropheids, this lightly-built reptile could instead be characterized by its relatively short neck as well as various skull features.
Prolacertoides is an extinct genus of archosauromorph reptile from the Early Triassic of China, the type species being Prolacertoides jimusarensis. Prolacertoides means 'like Prolacerta', in reference to Prolacerta, another genus of archosauromorph which Prolacertoides was once believed to have been closely related to. Prolacertoides is known from a single partial skull, IVPP V3233, which was discovered in Xinjiang in northwestern China. The locality of its discovery belongs to the Cangfanggou Group of the Jiucaiyuan Formation, which is dated to the Induan age of the very early Triassic.
Eorasaurus is an extinct genus of archosauromorph reptile known from the middle Late Permian of Tatarstan, European Russia. It contains a single species, Eorasaurus olsoni. When originally described by Sennikov (1997), Eorasaurus was identified as an early archosauromorph and assigned to the family Protorosauridae, Ezcurra et al. (2014) and Ezcurra (2016) later reclassified Eorasaurus and placed it within the group Archosauriformes. Eorasaurus is based solely on scant fossil material from the neck region, and is thus considered an unstable taxon in phylogenetic analyses. If Eorasaurus is an archosauriform, it would be the oldest known member of the group and would pre-date the previous record holder.
Asperoris is an extinct genus of archosauriform reptile known from the Middle Triassic Manda Beds of southwestern Tanzania. It is the first archosauriform known from the Manda Beds that is not an archosaur. However, its relationships with other non-archosaurian archosauriforms are uncertain. It was first named by Sterling J. Nesbitt, Richard J. Butler and David J. Gower in 2013 and the type species is Asperoris mnyama. Asperoris means "rough face" in Latin, referring to the distinctive rough texture of its skull bones.
Teyujagua is an extinct genus of small, probably semi-aquatic archosauromorph reptile that lived in Brazil during the Early Triassic period. The genus contains the type and only known species, T. paradoxa. It is known from a well-preserved skull, and probably resembled a crocodile in appearance. It was an intermediary between the primitive archosauromorphs and the more advanced Archosauriformes, revealing the mosaic evolution of how the key features of the archosauriform skull were acquired. Teyujagua also provides additional support for a two-phase model of archosauriform radiation, with an initial diversification in the Permian followed by a second adaptive radiation in the Early Triassic.
Kadimakara is an extinct genus of early archosauromorph reptile from the Arcadia Formation of Queensland, Australia. It was seemingly a very close relative of Prolacerta, a carnivorous reptile which possessed a moderately long neck. The generic name Kadimakara references prehistoric creatures from Aboriginal myths which may have been inspired by ice-age megafauna. The specific name K. australiensis relates to the fact that it was found in Australia. Prolacerta and Kadimakara were closely related to the Archosauriformes, a successful group which includes archosaurs such as crocodilians, pterosaurs, and dinosaurs.
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.
