A new species of Caipirasuchus (Notosuchia, Sphagesauridae) from the Late Cretaceous of Brazil and the evolutionary history of Sphagesauria

Abstract

Sphagesauridae is a group of notosuchian crocodyliforms from the Late Cretaceous of South America characterized by highly specialized jaws and dentition. Here, we describe a new sphagesaurid from the Santo Anastácio Formation (Caiuá Group, Bauru Basin), south-east Brazil. The specimen is composed of a partial palate, neurocranium, mandible and fragmentary teeth. It represents a new species that can be assigned to Caipirasuchus due to the presence of a lateromedially narrow and anteroposteriorly long mandibular symphyseal region, apicobasal ridges on the posterior teeth, a diastema between D5 and D6, and a linear row of large neurovascular foramina on the lateral surface of the dentary. It differs from previously described Caipirasuchus species based on a ventrolaterally inclined surface of the dentaries posterior to the tooth row, a connection between the anteroventral margin of the external mandibular fenestra and the floor of the Meckelian canal, and the anterior process of the angular forming a ‘V’-shaped suture in its contact with the splenial. The results of a phylogenetic analysis of notosuchians recovered the so-called ‘advanced notosuchians’ in a clade, for which we propose a phylogenetic definition and erect the name Sphagesauria. We also recovered two more inclusive clades encompassing an array of Mesozoic notosuchians, here named Xenodontosuchia, which includes Sphagesauria + Baurusuchia, and Eunotosuchia, including Xenodontosuchia, Uruguaysuchidae and other Cretaceous forms.

http://zoobank.org/urn:lsid:zoobank.org:pub:FD8D706F-9E01-4C09-BE4E-DC3BEDE151DC

Keywords:

• Caipirasuchus
• Sphagesauridae
• Santo Anastácio Formation
• Bauru Basin
• Notosuchia

Acknowledgements

We thank Joseph Sertich and Augustín Martinelli who provided many insightful comments that greatly improved the quality of the manuscript. We thank Rodrigo Machado, from Departamento Nacional de Produção Mineral, Ismar Carvalho, Flávia Figueiredo, and the staff of Departamento de Geologia – UFRJ and Museu de Paleontologia Professor Antônio Celso de Arruda for the access to the materials. A special thanks to Sandra Tavares for essential support in the collection of MPMA, thorough hospitality and strong coffee. Thiago Marinho and Júlio Marsola contributed discussions and important recommendations, and Douglas Ribeiro helped in the field and in the lab. We also thank the members of the Laboratório de Paleontologia – USP Ribeirão Preto, especially Paulo Ricardo Mendonça Lopes, for the skilful preparation of the material here described. This study is part of the project ‘A origem e irradiação dos dinossauros no Gondwana (Neotriássico – Eojurássico)’, funded by the Fundação de Amparo à Pesquisa do Estado de São Paulo – FAPESP (2014/03825-3), and ‘Core-facility for conservation of scientific documentation: biological collections and high technology research in comparative morphology’ (CT- INFRA 01/2013), funded by Financiadora de Estudos e Projetos – FINEP, Ministry of Science, Technology, Innovation and Communication, Brazilian Federal Government. This study was financed in part by the Coordenação de Aperfeiçoamento de Pessoal de Nível Superior – Brasil (CAPES) – Finance Code 001, FAPESP (2018/18145-9 to MB) and FAPESP (2019/10620-2 to GSF).

Supplemental material

Supplemental material for this article can be accessed here: https://doi.org/10.1080/14772019.2021.1888815.

Associate Editor: Jonah Choiniere