Santa Maria Formation
The Santa Maria Formation is a sedimentary rock formation found in Rio Grande do Sul, Brazil. It has a Late Anisian to Early Norian age, and is notable for its fossils of early dinosaurs and other dinosauromorphs, including the herrerasaurid Staurikosaurus, the basal sauropodomorphs Buriolestes and Saturnalia, and the lagerpetid Ixalerpeton. It received this name because it was discovered first in the city of Santa Maria, on the central region of Rio Grande do Sul state.
The distinguished English paleontologist Arthur Smith Woodward determined the age of Santa Maria Formation dated Mesozoic Era, Upper Triassic period. A U-Pb dating of a locality of the Upper portion of the Santa Maria Formation dated around 233.23±0.73 million years ago, putting that locality 1.5 million years older than the Ischigualasto Formation, instead being in the temporal range of the Los Chañares Formation, and making the two formations approximately equal as having the earliest dinosaur localities.
The Santa Maria Formation is part of the Candelária Sequence, and is biostratigraphically subdivided into Dinodontosaurus, Santacruzodon, and Hyperodapedon Assemblage Zones. Moreover, the Hyperodapedon Assemblage Zone is subdivided into Hyperodapedon Acme Zone and Exaeretodon Sub-Zone. These subdivisions are also known as Lower and Upper Hyperodapedon Assemblage Zone, respectively.Fauna
Synapsids
Archosauromorphs">Archosauromorpha">Archosauromorphs
Formations
