The Mangrullo Formation is an Early Permian (Artinskian) fossiliferous geological formation in northeastern Uruguay. Some authors alternatively group it together with the Paso Aguiar Formation and the Frayle Muerto Formation as the three subdivisions of the Melo Formation, in which case it is referred to as the Mangrullo Member. Like the correlated formations of Irati and Whitehill, it is known for its abundant mesosaur fossils. It also contains the oldest known Konservat-Lagerstätte in South America, as well as the oldest known fossils of amniote embryos.
Outcrops and stratigraphic column of the Mangrullo Formation
The Mangrullo Formation is a part of the Paraná Basin (Bacia do Paraná)
Mesosaurus tenuidens
M. tenuidens
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. Exposures of the Irati Formation are to be found in the South, southeastern Brazil and in the states of Goiás, Mato Grosso, São Paulo, Paraná, Santa Catarina, Rio Grande do Sul and Mato Grosso do Sul. 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. The Irati Formation, with a maximum thickness of 80 metres (260 ft), was defined and named by White in 1908.
The Paraná Basin in South America
Reconstruction of Mesosaurus
Reconstruction of Stereosternum