Craniodental reinterpretations and new specimens of Protuberum cabralense, a bizarre traversodontid cynodont from the earliest Late Triassic of Brazil

• Published in: Journal of South American earth sciences 2024-12, Vol.149, p.105213, Article 105213
• Main Authors: Schmitt, Maurício Rodrigo, Martinelli, Agustín Guillermo, Fonseca, Pedro Henrique Morais, Schultz, Cesar Leandro, Soares, Marina Bento
• Format: Article
• Language: English
• Subjects: Gomphodontosuchinae; Santa Maria Supersequence; South America; Traversodontidae
• ISSN: 0895-9811
• DOI: 10.1016/j.jsames.2024.105213

Traversodontid cynodonts form one of the most abundant tetrapod clades in continental Triassic beds of southern Brazil, with more than eleven species described. Within this clade, Protuberum cabralense is one of its most bizarre members, characterized by a robustly built skull and the presence of rounded protuberances in the dorsal surface of the ribs, ilium and neural spines in presacral vertebrae. The holotype and paratypes were collected in the 1970's but described only in 2009, being positioned in the clade Gomphodontosuchinae. Here we reanalyzed the skull of the holotype specimen and reinterpreted some anatomical traits, such as the number of upper incisors, position of the paracanine fossa, number of postcanines, morphology of the pterygo-paraoccipital foramen, among others. Through CT scan images the endocranial cavities are described and compared with Santagnathus mariensis (whose endocranial cavities are firstly described here) and other traversodontids. Also, two new occurrences of the species are presented, increasing its geographical distribution within the Dinodontosaurus Assemblage Zone (Pinheiros-Chiniquá Sequence, latest Ladinian-earliest Carnian) and its relevance to biostratigraphy. The reinterpretation of several traits resulted in a novel phylogenetic placement for Protuberum cabralense, nested outside the Gomphodontosuchinae clade, even as an earlier divergent than massetognathine forms. •New interpretations on upper incisors and canine of Protuberum.•Redescription of its dentition and improvement on phylogenetic scores.•New phylogenetic position for Protuberum, outside Gomphodontosuchinae.•3D reconstruction of its endocranial cavities using CT.•New records of Protuberum from two new outcrops, with biostratigraphic significance.