The Sarmiento Formation ( Spanish: ''Formación Sarmiento''), in older literature described as the Casamayor Formation, is a geological formation in Chubut Province, Argentina, in central Patagonia, which spans around 30 million years from the mid- Eocene to the early Miocene. It predominantly consists of

pyroclastic Pyroclastic rocks (derived from the el, πῦρ, links=no, meaning fire; and , meaning broken) are clastic rocks composed of rock fragments produced and ejected by explosive volcanic eruptions. The individual rock fragments are known as pyroc ...

deposits, which were deposited in a semi-arid environment. It is divided up into a number of members. The diverse fauna of the Sarmiento Formation, including a variety of birds, crocodilians, turtles and snakes, also includes many mammals such as South American native ungulates ( notoungulates, litopterns,

astrapotheres Astrapotheria is an extinct order of South American and Antarctic hoofed mammals that existed from the late Paleocene to the Middle Miocene, ."The uruguaytheriine Astrapotheriidae from the rich middle Miocene Honda Group of the upper Magdalena R ...

) as well as

armadillo Armadillos (meaning "little armored ones" in Spanish) are New World placental mammals in the order Cingulata. The Chlamyphoridae and Dasypodidae are the only surviving families in the order, which is part of the superorder Xenarthra, along wi ...

s, and caviomorph rodents. CC-BY_icon

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Paleofauna

Amphibians

Birds

Reptiles

Crocodylomorphs

Lepidosaurs

Testudines

Mammals

Meridiolestidans

Meridiungulates

Xenarthrans

Metatherians

Rodents

Primates

Bats

References

{{SALMA Geologic formations of Argentina Miocene Series of South America Oligocene Series of South America Eocene Series of South America Paleogene Argentina Neogene Argentina Casamayoran Divisaderan Tinguirirican Deseadan Colhuehuapian Fossiliferous stratigraphic units of South America Paleontology in Argentina Sandstone formations Mudstone formations Lacustrine deposits Geology of Chubut Province Golfo San Jorge Basin Tuff formations