| Rio do Rasto Formation | |
|---|---|
| Stratigraphic range: Wordian to Wuchiapingian ~ | |
| Type | Geological formation |
| Unit of | Paraná & Pelotas Basins |
| Sub-units | Morro Pelado Mb., Serrinha Mb. |
| Underlies | Pirambóia Formation (Paraná Basin) Botucatu Formation (Pelotas Basin) |
| Overlies | Teresina Formation |
| Lithology | |
| Primary | Shale, sandstone |
| Location | |
| Coordinates | 28°24′26″S 49°32′46″W / 28.40722°S 49.54611°W |
| Approximate paleocoordinates | 41°18′S 22°24′W / 41.3°S 22.4°W |
| Region | Paraná, Santa Catarina, Rio Grande do Sul |
| Country |  Brazil |
| Extent | Paraná Basin |
 Extent of Paleozoic (including the Rio do Rasto Formation) and Mesozoic units in the Paraná Basin in light blue | |
The Rio do Rasto Formation is a Late Permian sedimentary geological formation in the South Region of Brazil. The official name is Rio do Rasto, although in some publications it appears as Rio do Rastro.
The strata were deposited between the Wordian and the Wuchiapingian, from about 266 to 254 million years ago. The geology, alongside its paleobiota, indicate that the locality was a freshwater environment. Some of the animals discovered in the formation include Tiarajudens, Parapytanga and Pampaphoneus.