The dental anatomy of Candelariodon barberenai from the Dinodontosaurus Assemblage Zone (Pinheiros-Chiniquá Sequence, Santa Maria Supersequence, late Ladinian–early Carnian) of south Brazil, is redescribed. Candelariodon was originally classified as Eucynodontia incertae sedis and our analysis recovered this taxon deeply nested within Probainognathia, as the sister taxon of Potheriodon plus Prozostrodontia. The lower postcanine dentition of Candelariodon has several apomorphies shared with Prozostrodon, Santacruzgnathus, Brasilodon/Brasilitherium, and some basal mammaliaforms (Morganucodon, Megazostrodon), such as a lingual cingulum with discrete cusps e and g and two distinct morphologies in the tooth row. The reinterpretation of Candelariodon as a probainognatian cynodont more derived than Probainognathus and the rich Brazilian fossil record document an important adaptive radiation of non-mammaliaform prozostrodontians and closely related forms prior to the origin of the mammaliaform clade.

Key words: Cynodontia, Probainognathia, Prozostrodontia, Dinodontosaurus Assemblage Zone, South America, Brazil.

Agustín G. Martinelli [agustin_martinelli@yahoo.com.ar], Marina Bento Soares [marina.soares@ufrgs.br], Pablo G. Rodrigues [pablogr@bol.com.br], and Cesar L. Schultz [cesar.schultz@ufrgs.br], Laboratório de Paleontologia de Vertebrados, Departamento de Paleontologia e Estratigrafia, Instituto de Geociências, Universidade Federal do Rio Grande do Sul (UFRGS), Av. Bento Gonçalves 9500, Agronomia, 91540-000, Porto Alegre, RS, Brazil. Téo Veiga de Oliveira [teovoli@yahoo.com.br], Divisão de Mamíferos do Museu de Zoologia da UEFS, Departamento de Ciências Biológicas, Universidade Estadual de Feira de Santana (UEFS), Av. Transnordestina s/n, Bairro Novo Horizonte, 44036-900, Feira de Santana, BA, Brazil.