An updated taxonomic revision of the species of Mourasuchus (Alligatoroidea, Caimaninae)

ABSTRACT

Mourasuchus is one of the most well-known components of the notable South American crocodylomorph fauna of the Cenozoic. There has been a recent renewed interest in the taxonomy of Mourasuchus, but some issues remained. This study addressed the taxonomic problems of the genus, concluding that there are four valid species: M. amazonensis (Price 1964), M. atopus , M. arendsi (Bocquentin-Villanueva 1984) and M. pattersoni (Cidade et al. 2017). M. arendsi may be a junior synonym of M. atopus, but this can only be evaluated through an eventual reanalysis of the ventral aspect of the skull of the holotype of M. arendsi. The specimens LACM-160157, UFAC-1424 and UFAC-5883 may either belong to M. amazonensis or represent a new species, which can be evaluated only through an eventual reanalysis of the dorsal aspect of the skull of the holotype of M. amazonensis. Mourasuchus nativus is considered a nomen dubium as its holotype is indistinguishable from at least two other Mourasuchus species: M. arendsi and either M. amazonensis or the possible new species represented by LACM-160157, UFAC-1424 and UFAC-5883. This study stresses the importance of taxonomic accuracy to comprehend fossil faunas, including remarkably diverse ones like South American cenozoic crocodylomorphs.

KEYWORDS:

• Mourasuchus
• Caimaninae
• Crocodylia
• taxonomy
• Miocene
• South America

Acknowledgments

We are grateful to the following people for access to collections: Gina Oneda (CIAAP), Ascánio Rincón (IVIC), Sam McLeod and Vanessa Rhue (LACM), Hyram Moreno (MCNC), Rodrigo Machado (MCT), Marcelo Reguero (MLP), Patricia Holroyd (UCMP) and Edson Guilherme, Jonas Pereira de Souza-Filho and Carlos D’Apólito (UFAC). We thank Renata Stopiglia (UFRJ) for discussions on taxonomic issues and Edson Guilherme, Carlos D’Apólito (UFAC) and Rafael Costa da Silva (MCT) for information on the specimens under their care. We are indebted to reviewers Andrés Solórzano, Francisco Barrios and Paula Bona for insightful suggestions and criticism that significantly improved the manuscript.

Disclosure statement

No potential conflict of interest was reported by the author(s).

Additional information

Funding

The work was supported by the Conselho Nacional de Desenvolvimento Científico e Tecnológico [310948/2021-5] and Fundação de Amparo à Pesquisa do Estado de São Paulo [2013/04516-1].