Prestosuchus (meaning "Prestes crocodile") is an extinct genus of pseudosuchian in the group Loricata, which also includes Saurosuchus and Postosuchus.

[1] The holotype of Prestosuchus chiniquensis was discovered by Wilhelm Rau alongside the holotype of Rauisuchus tiradentes in the Santa Maria Formation at the Paleontological Site Chiniquá, near the city of São Pedro do Sul in 1928 or 1929, and the fossils were shipped back to Germany for study by the German paleontologist Friedrich von Huene.

One specimen was a partial skeleton including a jaw and snout fragments, and its bones were labelled SNSB-BSPG AS XXV 1-3, 5-11, 28-41, and 49.

Another specimen, SNSB-BSPG AS XXV 7, consists of the upper part of the hip and sacrum and was designated the paralectotype of the species.

Although Kischlat (2000) assigned the paralectotype hip material to "Karamuru vorax",[4][5] its original referral to P. chiniquensis was upheld by Desojo et al. (2020) when the specimen was redescribed along with the lectotype.

These two specimens were originally described by von Huene (1938) and are stored at the Bavarian State Collection for Palaeontology and Geology (Bayerische Staatsammlung für Paläontologie und Geologie, BSPG) institute of the Bavarian Natural History Collections (Staatliche Naturwissenschaftliche Sammlungen Bayerns, or SNSB) in Munich, Germany.

[5] However, this name was also poorly defined and never formalized, so "Karamuru vorax" is considered a nomen nudum along with "Abaporu" loricatus.

[10] Other paleontologists have informally disagreed with this argument,[11] and publications relevant to Prestosuchus have consistently treated P. chiniquensis as a valid type species.

[18] The least complete UFRGS specimen is UFRGS-PV-0473-T, an isolated braincase which may be from the "Posto de Gasolina" outcrop in Dona Francisca.

[15] Porto Alegre has one additional Prestosuchus specimen unaffiliated with the UFRGS: MCP-146, a portion of the hip area stored at the Museu de Ciências e Tecnologia of Pontífícia Universidade do Rio Grande do Sul.

One of the most spectacular specimens, ULBRA-PVT-281, consists of a very large and complete skull and partial skeleton discovered at "Posto de Gasolina" and now stored at the Universidade Luterena do Brasil (ULBRA) in Canoas.

This specimen was discovered in 2010 and was fully described by Roberto-Da-Silva et al. (2018/2019)[20][12] The Museu Paleontológico e Arqueológico Walter Ilha in São Pedro do Sul has a selection of Prestosuchus fossils collectively termed CPEZ-239b.

[9] The only Prestosuchus fossil stored outside of Brazil or Germany is MCZ 4167, an obscure and fragmentary specimen found at "Posto de Gasolina".

[21] Stagonosuchus nyassicus is a possible loricatan known from two specimens discovered in the Manda Beds of Tanzania and originally described by von Huene (1938/1939).

Many specimens seemingly possessed a thin convex ridge ("roman nose") running along the midline of the elongated and narrow nasals, similar to Luperosuchus and Batrachotomus.

[9][16] Additional low, rough lateral ridges (similar to those of Rauisuchus) run along the upper edge of the snout from the nasal to the lacrimal and prefrontal.

[13][12][16] The jugal is relatively smooth in texture and has extensive sutures with the maxilla, lacrimal, and postorbital, as well as the V-shaped quadratojugal.

[16] The splenial, which lies on the inner surface of the dentary, is unusually elongated in Prestosuchus and extends as far forward as the second tooth in the jaw.

Such structures include a shelf at the rear of the surangular and a thick articular bone which has a tall retroarticular process with an inner prong pierced by a chorda tympani foramen.

[16] Cervical (neck) vertebrae are notably tall and their sides are excavated by large ventral depressions, which generates a keel on their lower edge.

Dorsal vertebrae further towards the hip have the parapophyses shift close to the diapophyses, fusing or eliminating some of the features they exhibit.

Prestosuchus also possessed two-headed dorsal ribs which were similar in shape to those of Batrachotomus, as well as a dense gastral basket.

Anterior caudals (those at the base of the tail) are higher than long and have tall neural spines that are slightly expanded at their tip.

The lower front portion of the scapula has a large acromion, which is unusually hook-shaped in the type specimen of P. chiniquensis due to an oval notch on its upper edge.

The tip of the shaft expands into a knob-like pubic boot like other loricatans, though it is much smaller than that of relatives such as Saurosuchus and Postosuchus.

However, Batrachotomus's crest smoothly transitions from the base of the ischium to the shaft, whereas an abrupt angled incision is observed in this area for P. chiniquensis and P. nyassicus.

The fourth trochanter manifests as a low, rough area rather than the pronounced knob or ridge present in most other archosaurs.

The foot has a phalangeal formula of 2-3-4-3-X, indicating that the fourth toe was much smaller than the second and third, an unusual trait among early loricatans.

[6] The cladogram below follows a simplified version of the strict reduced consensus tree by Desojo et al. (2020):[6] Avemetatarsalia Ornithosuchidae Revueltosaurus Aetosauria Gracilisuchidae Ticinosuchus Mandasuchus Poposauroidea Pagosvenator Saurosuchus Prestosuchus Batrachotomus Fasolasuchus Rauisuchus Polonosuchus Postosuchus Crocodylomorpha In 2013, a study of the structure of its hind limb bones inferred that Prestosuchus chiniquensis had 13 leg muscle groups in common with both crocodilians and birds (which together make up the two living groups of archosaurs) but only two muscle groups in common with only crocodilians, indicating that the musculature of Prestosuchus better represents a basal ("primitive") condition for archosaurs than it does a derived condition for crocodile-line or pseudosuchian archosaurs.

[18] In a study on bone microstructure, Prestosuchus chiniquensis was found to have had a slower growth pattern compared to other "rauisuchians", more reminiscent of that of some notosuchians and crocodilians.