Letrero Formation

Letrero Formation
Letrero Formation
Stratigraphic range: Late Miocene; (Mayoan-Montehermosan); ~11.6–5.3 Ma PreꞒ Ꞓ O S D C P T J K Pg N Aqu. Burdig. Lan. Ser. Tortonian M Z P
Type	Geological formation
Lithology
Primary	Siltstone
Other	Sandstone
Location
Coordinates	3.3°S 79.1°W
Approximate paleocoordinates	3.7°S 77.4°W
Region	Azuay Province
Country	Ecuador
Extent	Sierra Region
	Letrero Formation (Ecuador)

The Letrero Formation is a Late Miocene (Mayoan to Montehermosan in the SALMA classification) geologic formation in south-central Ecuador. The formation comprises lacustrine sediments with strong fluvial clastic input and contains siltstones and fine-grained sandstones.^[1]

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Mammals of the Letrero Formation
Genus	Species	Location	Material	Notes	Images
Litopterna^[1]	Indeterminate	RHM Locality 4		A litoptern.
Caviomorpha^[1]	Indeterminate	RHM Locality 4		A caviomorph rodent.
Nabondasypus^[2]	Nabondasypus maddeni	Nabón basin	Several osteoderms.	An armadillo.
Anadasypus^[3]	A. aequatorianus	RHM Locality 4		A member of cingulata.
Toxodontia^[1]	Indeterminate	RHM Locality 4		A toxodont.

Fossil content

Letrero Formation
Stratigraphic range: Late Miocene (Mayoan-Montehermosan) ~11.6–5.3 Ma PreꞒ Ꞓ O S D C P T J K Pg N Aqu. Burdig. Lan. Ser. Tortonian M Z P
Type	Geological formation
Lithology
Primary	Siltstone
Other	Sandstone
Location
Coordinates	3.3°S 79.1°W / -3.3; -79.1
Approximate paleocoordinates	3.7°S 77.4°W / -3.7; -77.4
Region	Azuay Province
Country	Ecuador
Extent	Sierra Region
Letrero Formation (Ecuador)