The marine crocodile Maledictosuchus (Thalattosuchia, Metriorhynchidae) from the Kimmeridgian deposits of Tlaxiaco, Oaxaca, southern Mexico

Abstract

Metriorhynchidae is a family of highly specialized, extinct marine crocodylomorphs that inhabited the Paleopacific Ocean and the Tethys Sea during the Jurassic and the Early Cretaceous. Numerous metriorhynchid fossil specimens have been recovered from European and South American localities, but North American records of this family are still scarce. Here, we describe a recently recovered Kimmeridgian metriorhynchid from the Sabinal Formation, Tlaxiaco Basin, Oaxaca, Mexico, that is attributable to the genus Maledictosuchus. This genus was known previously from a single species, M. riclaensis, from the Middle Jurassic of Spain. The characteristics of this Mexican specimen support its identification as a new species, Maledictosuchus nuyivijanan, sp. nov. The two species differ in dental and skull-roof morphology. The frontal of M. nuyivijanan, sp. nov., has a wide, rounded anterior end that extends rostrally to the same level of the anterior end of the prefrontal, whereas the frontal of M. riclaensis has a narrow anterior end that is located posterior to the anterior end of the prefrontal. Additionally, the teeth of M. nuyivijanan, sp. nov., exhibit bicarinated crowns, a smooth labial surface, and a lingual surface ornamented with longitudinal ridges, whereas those of M. riclaensis lack carinae and the labial and lingual surfaces are covered with considerably more conspicuous ridges. The North American occurrence of M. nuyivijanan, sp. nov., suggests a wider temporal and geographic distribution for the genus Maledictosuchus across the Tethys Sea than previously thought: from the Callovian in Europe to the Kimmeridgian in southern North America.

http://zoobank.org/urn:lsid:zoobank.org:pub:6F6CC892-B6E1-4069-AF3A-D05792AC0F7A

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Citation for this article: Barrientos-Lara, J. I., J. Alvarado-Ortega, and M. S. Fernández. 2018. The marine crocodile Maledictosuchus (Thalattosuchia, Metriorhynchidae) from the Kimmeridgian deposits of Tlaxiaco, Oaxaca, southern Mexico. Journal of Vertebrate Paleontology. DOI:10.1080/02724634.2018.1478419.

ACKNOWLEDGMENTS

We first thank S. Jouve and an anonymous reviewer for providing a thorough and helpful review of this manuscript. We owe our gratitude to the local people of Tlaxiaco, especially to Mr. J. F. Cisneros and his nephew A. A. Cruz, who helped us in multiple tasks during the field works. We also thank all students and paleontologists involved in the field work: R. Hernández-Rivera, C. Nuñez-Alfaro, F. T. Guitérrez-Zamora, J. Diaz-Cruz, D. García-Alcántara, A. González-Cervantes, M. U. Rosendo-Brito, O. Victoriano-Taboada, and I. R. Espinoza-Encinas. UNAM supported this research through the projects DGAPA-PAPIIT IN207314 and IN 209017. Mr. G. Álvarez-Reyes helped us with the fossil preparation. M. del P. Melgarejo-Damián provided valuable suggestions to improve this work. Mr. J. M. Contreras and Dr. A. M. Reyes took the photographs included in this article. M. Reguero, A. Garrido, J. Aguilar, and J. M. Padilla kindly provided access to the fossil collection of MLP, MOZ, UANL FCT, and MUDE, respectively.