| Peirosaurus Temporal range: Late Cretaceous, 85–65 Ma |
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| Scientific classification | |
| Kingdom: | Animalia |
| Phylum: | Chordata |
| Class: | Reptilia |
| Superorder: | Crocodylomorpha |
| Suborder: | †Notosuchia |
| Family: | †Peirosauridae |
| Genus: | †Peirosaurus Price, 1955 |
| Species | |
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Peirosaurus is an extinct genus of peirosaurid crocodylomorph. It is the type genus of the family Peirosauridae.[1] Fossils of the type species P. tormini, first described in 1955, have been found from the Marília Formation in Uberaba, Brazil[2][3] and date back to the late Maastrichtian stage of the Late Cretaceous.[4] The genus is known from a partial skull and several postcranial elements such as vertebrae and dermal plates. Material of the genus is also known from the Bajo de la Carpa Formation in Argentina.
Peirosaurus has a ziphodont dentition that is somewhat heterodont, with conical premaxillary teeth and serrated maxillary and posterior mandibular teeth. The rostrum is laterally compressed with a grove between the maxilla and premaxilla to accommodate for an enlarged mandibular tooth. A maxillary wedge-like anterior process is also present. The external nares face slightly forward and anteriorly protrude. The dorsal osteoderms are thin and sculptured with low longitudinal keels while the abdominal ones are smaller and lack keels.
Peirosaurus shares a number of features with the closely related genus Uberabasuchus, found from the same locality in Uberaba. These include a similar tooth size pattern and the large maxillary anterior process. However, the rostrum of Uberabasuchus is more compressed than that of Peirosaurus, which is relatively broad.[5]
The occurrence of Peirosaurus in both Argentina and Brazil provides evidence for the interchange of crocodylomorphs that is thought to have occurred as a result of the connection of the drainage systems of southern Argentina and central South America throughout the Late Cretaceous in the Bauru Basin.[5]