| Irati Formation | |
| Period: | Early Permian |
| Age: | Early Permian ~ |
| Type: | Geological formation |
| Prilithology: | Black shale |
| Otherlithology: | Sandstone |
| Unitof: | Passa Dois Group |
| Underlies: | Serra Alta Formation (Paraná Basin) Teresina Formation (Pelotas Basin) |
| Overlies: | Palermo Formation |
| Thickness: | up to 80m (260feet) |
| Area: | 1000000km2 |
| Map: | South America satellite plane Bacia do Parana.jpg |
| Coordinates: | -25.5°N -50.7°W |
| Region: | Paraná & Pelotas Basins Goiás, Mato Grosso do Sul, Mato Grosso, São Paulo, Paraná, Santa Catarina, Rio Grande do Sul |
| Namedby: | White |
| Year Ts: | 1908 |
| Paleocoordinates Ts: | -45.8°N -29.7°W |
Irati Formation is the name of a geological formation of the Paraná Basin in Brazil. It has previously been dated as Late Permian using palynomorphs, but is now dated as Early Permian using zircon ages obtained from bentonite layers. The base of the formation has been dated at 278.4 ± 2.2 Ma.[1] [2] Exposures of the Irati Formation are to be found in the South (Geopark of Paleorrota), southeastern Brazil and in the states of Goiás, Mato Grosso, São Paulo, Paraná, Santa Catarina, Rio Grande do Sul and Mato Grosso do Sul.[1] The formation is part of the Passa Dios Group, underlying the Serra Alta Formation and overlying the Palermo Formation. The formation has been deposited in a restricted marine environment.[3] The Irati Formation, with a maximum thickness of 80m (260feet), was defined and named by White in 1908.[4]
| Reptiles of the Irati Formation | |||||||
|---|---|---|---|---|---|---|---|
| Genus | Species | Location | Stratigraphic position | Material | Notes | Image | |
| Brazilosaurus | B. sanpauloensis | A mesosaurid mesosaur | |||||
| Mesosaurus | M. tenuidiens | A mesosaurid mesosaur | |||||
| Stereosternum | S. tumidum | A mesosaurid mesosaur | |||||
| Fish of the Irati Formation | |||||||
|---|---|---|---|---|---|---|---|
| Genus | Species | Location | Stratigraphic position | Material | Notes | Images | |
| Amelacanthus | A. sp. | A ctenacanthid shark | |||||
| Fairchildodus[5] | F. rioclarensis | A petalodont | |||||
| Iratiacanthus | I. santamariaensis | A sphenacanthid shark | |||||
| Itapyrodus | I. punctatus | A petalodont | |||||
| Orodus | O. ipeunaensis | A orodontid shark | |||||
| Sphenacanthus | S. sanpauloensis | A sphenacanthid shark | |||||
| Taquaralodus | T. albuquequei | A diplodoselachid shark | |||||
| Xenacanthus | X. pricei | A Xenacanthid shark | |||||
| Sauropods of the Irati Formation | |||||||
|---|---|---|---|---|---|---|---|
| Genus | Species | Location | Stratigraphic position | Material | Notes | Images | |
| Iraticaris | I. damiani | ||||||
| Myelontordoxylon | M. camposii | ||||||
| Permocaris | P. purperae | ||||||
| Pittinucaris | P. wuerdigae | ||||||