title: Two New Cynodonts (Therapsida) from the Middle-Early Late Triassic of Brazil and Comments on South American Probainognathians.
abstract: We describe two new cynodonts from the early Late Triassic of southern Brazil. One taxon, Bonacynodon schultzi gen. et sp. nov., comes from the lower Carnian Dinodontosaurus AZ, being correlated with the faunal association at the upper half of the lower member of the Chañares Formation (Ischigualasto-Villa Unión Basin, Argentina). Phylogenetically, Bonacynodon is a closer relative to Probainognathus jenseni than to any other probainognathian, bearing conspicuous canines with a denticulate distal margin. The other new taxon is Santacruzgnathus abdalai gen. et sp. nov. from the Carnian Santacruzodon AZ. Although based exclusively on a partial lower jaw, it represents a probainognathian close to Prozostrodon from the Hyperodapedon AZ and to Brasilodon, Brasilitherium and Botucaraitherium from the Riograndia AZ. The two new cynodonts and the phylogenetic hypothesis presented herein indicate the degree to which our knowledge on probainognathian cynodonts is incomplete and also the relevance of the South American fossil record for understanding their evolutionary significance. The taxonomic diversity and abundance of probainognathians from Brazil and Argentina will form the basis of deep and complex studies to address the evolutionary transformations of cynodonts leading to mammals.
authors.affiliation: Laboratório de Paleontologia de Vertebrados, Departamento de Paleontologia e Estratigrafia, Instituto de Geociências, Universidade Federal do Rio Grande do Sul (UFRGS), Ave. Bento Gonçalves 9500, Agronomia, 91540-000, Porto Alegre, RS, Brazil.
authors.forename: Agustín G
authors.identifier: http://orcid.org/0000-0003-4489-0888
authors.initials: AG
authors.lastname: Martinelli
authors.affiliation: Laboratório de Paleontologia de Vertebrados, Departamento de Paleontologia e Estratigrafia, Instituto de Geociências, Universidade Federal do Rio Grande do Sul (UFRGS), Ave. Bento Gonçalves 9500, Agronomia, 91540-000, Porto Alegre, RS, Brazil.
authors.forename: Marina Bento
authors.initials: MB
authors.lastname: Soares
authors.affiliation: Instituto Federal de Educação, Ciência e Tecnologia do Rio Grande do Sul, Campus Porto Alegre, Rua Coronel Vicente 281, Centro Histórico, 90030-040, Porto Alegre, RS, Brazil.
authors.forename: Cibele
authors.initials: C
authors.lastname: Schwanke
mesh_terms: D000818:Animals; D001938:Brazil; D043344:Chordata / Q000033:anatomy & histology* / Q000145:classification; D003724:Dental Arch / Q000033:anatomy & histology; D005580:Fossils; D007568:Jaw / Q000033:anatomy & histology; D010802:Phylogeny; D012886:Skull / Q000033:anatomy & histology