Brasinorhynchus mariantensis

Brasinorhynchus mariantensis is a rhynchosaur from the Middle Triassic Santa Maria Formation of southern Brazil. It was first discussed as the “Mariante rhynchosaur” before being formally named in 2016. Two specimens form its type material: a complete skull with the first three neck vertebrae, and a separate set of right jaw bones. Together they preserve more of the head than either specimen alone, while leaving the body largely unknown. Its tooth-bearing jaws support plant processing, and phylogenetic analysis places it among stenaulorhynchine rhynchosaurs. The species belongs in the other fossil reptile catalogue, a navigation group containing many unrelated reptiles.

Quick facts

From a locality nickname to a formal genus

The fossils were informally called the “Mariante rhynchosaur” after Porto Mariante in Rio Grande do Sul. Cesar Schultz, Max Langer and Felipe Montefeltro formally described Brasinorhynchus mariantensis in 2016. The holotype, UFRGS-PV-0168-T, preserves a complete skull without the lower jaw, together with the atlas, axis and third cervical vertebra. The paratype, UFRGS-PV-0315-T, adds right maxillary and lower-jaw bones. Both specimens are curated at the Federal University of Rio Grande do Sul in Porto Alegre.

The two fossils complement one another, but they do not make a complete skeleton. Most of the trunk, pelvis and limbs are unknown. Any whole-body image therefore relies on comparisons with other rhynchosaurs, and the proportions of the missing regions cannot be checked against a Brasinorhynchus skeleton.

A beak and tooth-bearing jaws

The front of the snout ends in a downturned, toothless bony beak. Behind it, the upper jaw carries tooth-bearing surfaces that would have met the lower teeth during feeding. The separate paratype is especially useful because it preserves parts of both sides of that interaction. As in other rhynchosaurs, teeth were added and worn as the animal grew.

The jaw apparatus supports herbivory and the processing of plant material. It does not identify a particular plant, because neither stomach contents nor a diagnostic coprolite has been securely associated with the genus. A robust beak can crop vegetation, but the fossil record does not show the exact bite sequence or daily diet.

Position among rhynchosaurs

The original phylogenetic analysis placed Brasinorhynchus within Stenaulorhynchinae, close to the African Stenaulorhynchus. This branch differs from the later hyperodapedontine rhynchosaurs that became widespread toward the end of the Triassic. The position is an inference from a matrix of skeletal characters, and it may change as other fragmentary taxa are revised.

The Ladinian occurrence places Brasinorhynchus late in the known history of stenaulorhynines. It predates the wider record of some later relatives, but this pattern alone does not establish a direct ancestor–descendant chain. A comparison with other rhynchosaur jaw and skull material helps identify shared characters without turning one genus into a stand-in for another.

Santa Maria landscapes and limits

The type locality belongs to the Pinheiros–Chiniquá sequence of the Santa Maria Formation, associated with the Dinodontosaurus Assemblage Zone. Middle Triassic river and floodplain deposits in the region preserve dicynodonts, cynodonts and archosauromorphs. The formation records a changing landscape and fauna, not a single snapshot in which every named animal lived together.

The skull is the strongest basis for restoring the head and its beak. The first three neck vertebrae provide a short view of the front of the spine; body mass, gait, soft tissues and colour remain uncertain. Brasinorhynchus is a non-dinosaurian archosauromorph, comparable broadly with other rhynchosaurs but separated by time, geography and branch. The catalogue keeps the taxon's diagnostic fossils visible without disguising the large gaps in its record.