Kinesuchus

The holotype of Kinesuchus, MAU-Pv-CO-583, is an incomplete lower jaw that was recovered from the Cerro Overo locality of Argentina′s Bajo de la Carpa Formation. The locality, which is located southwest of Rincón de Los Sauces in the Neuquen Province, had previously only yielded fragmentary vertebrate fossils other than the sauropod Overosaurus. The mandible was described in 2018 by Leonardo S. Filippi, Francisco T. Barrios and Alberto C. Garrido. The genus name Kinesuchus combines the Mapuche word "kiñe", which means "one", and the Ancient Greek "souchos", derived from the Egyptian crocodile-headed deity Sobek. The species name "overoi" meanwhile is a reference to the Cerro Overo locality where the holotype was found. Together the names were chosen to reflect that Kinesuchus was the first of its group to have been recovered from this locality. ==Description==

Kinesuchus is characterized by possessing an elongated and spatulate mandibular symphysis somewhat resembling that of Itasuchus that indicates a relatively long snout. The mandibular symphysis reachests its greatest width at the level as the presumably enlarged fourth dentary tooth, after which the entire mandible grows narrower until the position of the eight and ninth alveoli, where it is markedly constricted before diverging again from this point onward. Such a constriction is not typical in long-snouted peirosaurids, only found to a lesser degree in Itasuchus and oreinirostral forms like Montealtosuchus. The splenials contact the dentaries along a V-shaped suture with a pointed end and slightly concave edges similar to what can be observed in other long-snouted peirosaurids. Through the splenials contribution the symphysis extends until roughly the 12th alveolus, which is further back than in most other peirosaurids. The alveoli in the space between these peaks are described as subequal in size, but larger than the first three alveoli of the lower jaw. The fourth alveolus is separated from its immediate successor by a short toothless gap or diastema as is seen in Bayomesasuchus and most of the alveoli are well separated by distinct bony septa. Conversely, further in the back of the jaw, behind the tenth alveolus, the alvoeli are confluent with each other, sitting in a groove located between the dentary and splenial. The individual teeth can be separated into incisiviforms, caniniforms and postcaniniforms, though very few are actually preserved in the type specimen and all share a conical shape. The preserved incisiform is described as medium-sized with an anterodorsal (forward and upward) curvature and lacking a cutting edge. The fourth alveolus would have housed an enlarged caniniform, the largest in the lower jaw. The other preserved teeth are located much further in the back of the jaw, being the tenth and 12th. The tenth tooth is described as almost triangular with a slight labiolingual curvature while being positioned in a way that causes it to project outward from the jaw. The much larger 12th tooth meanwhile is described as more triangular but less curved while projecting outward at the same 75° angle. Unlike the anterior incisiform these posteriorforms not only possess carinae but furthermore preserve denticles lining the cutting edge, making them ziphodont. ==Phylogeny==

The relationship between Kinesuchus and other notosuchians has been subject to change throughout its research history. Filippi and colleagues initially assigned Kinesuchus simply to the family Peirosauridae, but did not provide a more in-depth phylogenetic analysis. The same position was also recovered by Iori et al. in 2025 in their description of Ibirasuchus. ==Paleobiology==

Kinesuchus was discovered at the Cerro Overo locality of Argentina′s Bajo de la Carpa Formation. The Bajo de la Carpa Formation has yielded a plethora of fossil remains across its various localities, including fish, turtles, squamates and a variety of both avian and non-avian dinosaurs. Among the largest animals were sauropods such as Overosaurus, Crocodylomorph remains are likewise common, with five taxa known from the area around Neuquen City, namely Notosuchus, Microsuchus, Comahuesuchus and Wargosuchus alongside an additional peirosaurid. Other Bajo de la Carpa crocodylomorphs in addition to these and Kinesuchus include Gasparinisuchus, Aquatic fauna is represented by the remains of lungfish and side-necked turtles such as podocnemidids and the chelid Lomalatachelys. While most of these are spread out across multiple localities, Overosaurus, Yeneen, Inawentu, both Llukalkan and Viavenator as well as the elasmarian ornithopod Mahuidacursor all come from the Cerro Overo – La Invernada locality that also yielded Kinesuchus. The environment of the Bajo de la Carpa Formation varied across its range. Around Sierra Barrosa the deposits indicate wide and shallow rivers with low-sinuosity, meaning their flow was relatively straight rather than winding and meandering. In the Cerro Senillosa sector the river channels appear to have been intertwined and are associated with sand dunes in the distal parts of the floodplain. A distal floodplain environment also dominates the Neuquén area, with the intertwined river channels being subject to periods of drying. The Cerro Overo – La Invernada area specifically indicates an anastomosed river system within a muddy floodplain with sandy load paleochannels deposits. Overall the climate of the Cretaceous Bajo de la Carpa Formation has been described as warm and semi-arid. == References ==