Work

A new hyperodapedontine rhynchosaur from a cynodont-dominated site (Upper Triassic) of southern Brazil

Year: 2026

Type: article

Abstract: We describe Isodapedon varzealis gen. et sp. nov., a new hyperodapedontine rhynchosaur from the Carnian deposits of the Candelária Sequence, southern Brazil. Phylogenetic analyses place this taxon outside known South American hyperodapedontines, including Macrocephalosaurus mariensis and ‘Hyperodapedon’ species, and support the restriction of the genus Hyperodapedon to its type species, thereby revealing greater diversity within the group than previously recognized. Isodapedon varzealis gen. et sp. nov. is characterized by symmetrical maxillary tooth bearing areas and distinctive dentary morphology, indicating divergent feeding adaptations relative to known rhynchosaurs. Stratigraphic occurrence in beds correlated with the Exaeretodon sub-zone of the Hyperodapedon Assemblage Zone, and its phylogenetic affinities with early diverging hyperodapedontines from Argentina and Scotland, imply a geographically widespread radiation of conservative morphotypes across southwestern Gondwana. This study highlights the complexity of Late Triassic rhynchosaur evolution and underscores the importance of continued palaeontological investigation in refining the taxonomy, biostratigraphy and palaeoecology of this key herbivorous clade.

Source: Royal Society Open Science

DOI: 10.1098/rsos.260176

Authors: Jeung Hee Schiefelbein, Maurício Silva Garcia, Mariana Doering, Rodrigo Temp Müller

Institution: Universidade Federal de Santa Maria

Language: English

Topic: Paleontology and Evolutionary Biology

Subfield: Paleontology

Field: Earth and Planetary Sciences

Domain: Physical Sciences

Open Access status: gold

Estimated APC paid: $1,471

Funders: Coordenação de Aperfeiçoamento de Pessoal de Nível Superior, Conselho Nacional de Desenvolvimento Científico e Tecnológico