Barreirosuchus is an extinct genus of itasuchid notosuchian known from the Late Cretaceous of São Paulo State, southeastern Brazil. It contains a single species, Barreirosuchus franciscoi. It most closely resembles Caririsuchus camposi from the Araripe Basin and Itasuchus jesuinoi also from the Bauru Basin, and shares with them several synapomorphies.
History and naming Barreirosuchus is known only from the holotype specimen MPMA-04-0012/00, an undeformed posterior portion of the skull with six teeth and a series of four vertebrae, two dorsal and two sacral. It was found in the year 2000 four kilometer from Monte Alto County, in the escarpment of the Serra do Jabuticabal within the Bauru Basin, corresponding to the Turonian to Santonian or possibly even Campanian Adamantina Formation. The fossil was recovered near a cave with the upper surface of the skull exposed and the anterior parts of the snout already eroded away. A more detailed redescription of the skull material was later published by Fachini and colleagues in 2025, not simply focusing on the external anatomy of the specimen but also detailing the internal anatomy, which were acquired via computed tomography.
Barreirosuchus was first named by Fabiano Vidoi Iori and Karina Lucia Garcia in 2012 and the type species is Barreirosuchus franciscoi. The generic name is derived from the name of the rural district of Barreiro, where the holotype was found. The specific name honors the paleontologist Cledinei Aparecido Francisco from the Museu de Paleontologia de Monte de Alto, for technical support during the excavations of the holotype.
Description The skull of Barreirosuchus is described as robust and though moderately tall still wider than tall. While most of the snout is missing the head has been inferred to have been roughly triangular in shape. Overall it closely resembles Caririsuchus and Pepsuchus, two closely related genera. The surface of the skull is ornamented by a pattern of small, circular pits, It has been interpreted as having had a flattend (platyrostral) snout. ridges and grooves, which are most prominent on the jugal and the skull table.
A prominent feature of Barreirosuchus is the presence of a median boss, a raised dome-like structure located before the eyes formed by the maxillae, prefrontals, lacrimal bones, nasal boness, jugals and the frontal bone. Such a boss is also present in Pepesuchus and some species of the extant genus Crocodylus including the Siamese crocodile and the extinct Crocodylus checchiai.
Little is preserved of the maxilla, but based on the holotype skull they were in contact with both the prefrontal and lacrimal bones, the paired nasal bones and the jugal. Iori and Garcia note that the contact between maxilla and jugal is relatively smooth rather than interfingering, suggesting that the bones overlapped each other. A notable feature unique to Barreirosuchus among peirosaurians is that the maxilla also participates in the orbital margin. Dorsally the bone forms a slender and elongated process that extends into the space between lacrimal and jugal until reaching the orbit. The nasals are likewise poorly preserved in the holotype and missing most their length, but it has been observed that they form distinct projections that inserts themselves both into the space between the prefrontal and frontal bone as well as into the space between the prefrontals and lacrimals. Furthermore, each nasal bears a small medial protrusion close to the contact with the prefrontal. There is no evidence for the presence of an antorbital fenestra, but there is a depression where the opening is be located in Stolokrosuchus
The lacrimal has been described as roughly rectangular or columnar and extends anterior beyond the tip of the neighbouring prefrontal. Near what Iori and Garcia described as the contact with the jugal the lacrimal bears a recess that delimits the rostral boss. Following Fachini and colleagues however, the contact between lacrimal and jugal is a lot more limited thanks to the facial process of the maxilla, restricting their meeting to a small part in the anteroventral orbital region. The team further highlights how the orientation of the posterior process the bone changes. Towards the front the lacrimal surface is directed mediolaterally, meaning comparably flat to even concave, but the process becomes increasingly dorsomedially sloping closer to the eyesocket as it forms the outer wall of the rostral boss. While it does not extend as far forward as the lacrimal, the prefrontal is actually more elongated and slightly inclined towards the back of the snout. Both the lacrimal and prefrontal form part of the opening eyesockets and bear a notch thought to be associated with the presence of a palpebral bone. The eyesockets of Barreirosuchus are located dorsolaterally, meaning they were positioned higher up on the skull than in terrestrial forms such as peirosaurids and baurusuchids. The frontal, as is related forms, consists of a wedge-shaped anterior process that makes up half the bones length and inserts itself between the prefrontals and the nasals and a rectangular posterior process located on the skull table. The surface of the anterior process appears slightly concave due to the fact that the edges of the eyesockets are weakly elevated.
The skull table is rectangular and broader than wide. Here the frontal comes in contact with the postorbitals towards its sides and the parietal bone along a highly sinuous suture while also forming a small part of the almost circular supratemporal fenestrae. The outer edge of the skull table is formed by the postorbital and the squamosal, which overhang the side of the skull including the infratemporal fenestra and the ear opening. While the prefrontal and lacrimal show signs of articulating with the palpebral, no such point of articulation is present on the postorbital. The postorbital and squamosal superficially contact each other around halfway down the length of the supratemporal fenestra, but looking at the skull from the side shows that the squamosal actually underlies its neighbour, separating it from the quadratojugal. The squamosal extends backward into a long straight process that surpasses the posterior edge of the parietal, which it contacts medially, and the occipital surface before ending in a rounded point. The parietal forms the space between the fenestrae and the medial posterior edge of the skull table, giving it an hourglass-shape. Looking at the skull from behind meanwhile shows that the parietal also bears a depression down along the midline flanked by two irregular processes, starting not far behind the supratemporal fenestrae similar to Pepesuchus and Rukwasuchus. The parietal is solely responsible for forming the posteromedial edge of the skull table while the supraoccipital is not visible on the surface of the element.
Following Fachini and colleagues the postorbital bar, formed by the descending process of the postorbital and the ascending process of the jugal, is long and slender, separating the eyesocket from the infratemporal fenestra. They note that the upper part of the bar is directed lateroventrally (downward but also somewhat flaring outward), but eventually transitions rather abruptly into a more outwards orientation towards the contact between the postorbital and jugal contributions of the structure. Overall the shape of postorbital bar of Barreirosuchus contributes to the depth of the skull, distancing the skull roof from the jugal. Aside from its contribution to the postorbital bar the jugal can be separated into an anterior and a posterior region. The former, which precedes the infratemporal fenestra, is described as expanded and robust, whereas the jugal bar is more cylindrical and narrower. Notably, the jugal bears a subtle concavity in its ventral surface that separates the two regions from each other when the skull is viewed from the side. The jugal is immediately followed by the long and narrow quadratojugal, which forms the posterior edge of the infratemporal fenestra, baring the quadrate from participating in the structure, and part of the margin for the external auditory meatus. The infratemporal fenestra itself is large, occupying most of the space below the small external auditory meatus and separating it from the postorbital bar. The bony otic aperture is likewise small, with Fachini and colleagues noting that its even smaller than the supratemporal fenestrae. The quadrate is noted for its significant posterior development, extending beyond the occipital condyle. Towards the skull table the quadrate also comes into contact with the descending process of the squamosal along a long, straight and backwards directed suture towards the edge of the occipital surface.
The quadrate is furthermore responsible for forming the point of articulation for the lower jaw, which projects outward and down from the bones main body beyond even the occipital surface. Here the quadrate bears two slender hemicondyles, one lateral and one medial with the surface of the articular facet half the length of the skull table.
The basicranium is oriented almost vertically and only really visible from the back. At the very top of the occipital surface sits the supraoccipital, which is prevented from appearing on the dorsal surface by the fact that its contact with the parietal sits at the junction between the dorsal and occipital surface. Therefore, the bone is only visible from behind just like in animals like Rukwasuchus and Stolokrosuchus. Overall, the bone is butterfly-shaped and wider than long, stretching across 65% of the width of the skull table. At the contact with the parietal the supraoccipital participates in forming the posttemporal fenestra. The supraoccipital is known to further contact both the occipital exposure of the squamosals and the otoccipitals, though its ventral-most contacts are unclear. It bears a short median crest that is flanked on either side by depressions that are deeper than those seen in Rukwasuchus and Hamdasuchus. The occipitally exposed parts of the squamosals are described as strongly concave and roofed by the overlying parts of the squamosals on the skull roof. The long contact between squamosal and quadrate at the side of the skull helps distinguish Barreirosuchus from Rukwasuchus, as this subsequently creates a long exposure along the outer edge of the occipital surface in contrast with the latter taxon's much shorter contact.
The exoccipitals or otoccipitals forms the lateral edges of the foramen magnum, the top of the occipital condyle and the paraoccipital processes. Compared to Rukwasuchus and several other peirosaurians the dorsal sections of the otoccipitals, which meet each other along the midline, are much less robust. Each paraoccipital process is likewise characterized as long and slender and ends far backward near the respective hemicondyle of the quadrate. Compared to related forms the paraocciptal processes of Barreirosuchus are bent further back and lack a rugose surface. The upper and lower parts of the otoccipital are separated by a pronounced step in the bone and also differentiated by their differing textures, with the part above the step being described as smooth while the ventral section is covered by striations. The ventral margin, near the contact to the parabasisphenoid and basioccipital, bears a long depression similar to Stolokrosuchus and less sharply defined than that of Rukwasuchus. The surface of the ventral otoccipital is perforated by a variety of openings for nerves such as the hypoglossal, vagus and glossopharyngeal nerves as well as the cranioquadrate passage.