Pebas Formation Explained

Pebas Formation
Period:	Miocene
Age:	Early Aquitanian-Tortonian (Colhuehuapian-Huayquerian) ~
Prilithology:	Siltstone, mudstone
Otherlithology:	Coal/lignite
Namedfor:	Pebas District
Region:	Amazon Basin
Country:
Coordinates:	-7.4°N -75°W
Paleocoordinates:	-8.4°N -70.6°W
Underlies:	Marañón Formation
Overlies:	Chambira Formation
Thickness:	~350-
Area:	1000000km2

The Pebas Formation is a lithostratigraphic unit of Miocene age, found in western Amazonia. The formation extends over 1000000km2, including parts of Brazil, Peru, Ecuador and Colombia.^[1] It is interpreted as representing the deposits of a lake ("Lake Pebas") or series of lakes, formed within the foreland basin of the Andes mountain belt. It is known for its abundant fossil ostracods and molluscs and an unusually diverse group of crocodylians.^[2]

Fossil content

Fish

Taxa	Species	Locality	Stratigraphic position	Material	Notes	Images
Anostomidae	Indeterminate
Hydrolycus	cf. H. sp.
Leporinus	L. sp.
Pristis	P. sp.
Potamotrygon	P. sp.

Insects

Taxa	Species	Locality	Stratigraphic position	Material	Notes	Images
Macroteleia	M. yaguarum				A parasitoid wasp.
Sycorax	S. peruensis				Relatives of moth flies and sand flies.

Mammals

Taxa	Species	Locality	Stratigraphic position	Material	Notes	Images
Dinomyidae	D. sp.				A hystricognath rodent.
Octodontoidea	Indeterminate.				A hystricognath rodent.
Neoepiblema^[3]	N. sp.				A hystricognath rodent.
Pebanista	P. yacuruna	Rio Napo.		A nearly complete skull.	A platanistid river dolphin.
Pseudoprepotherium	P. sp.	Rio Napo			A ground sloth.
Potamarchus	P. sp				A hystricognath rodent.
Parapropalaehoplophorus	P. sp				a glyptodont

Reptiles

Taxa	Species	Locality	Stratigraphic position	Material	Notes	Images
Caiman	C. wannlangstoni	Locality IQ26 and IQ114		A well-preserved partial skull.	An extinct caiman
Gavialoidea	Indeterminate.
Gnatusuchus	G. pebasensis	Locality IQ114, IQ116, and IQ125	Upper	A nearly complete skull.	A clam eating caiman.
Gryposuchus	G. pachakamue	Locality IQ101			A gavialid crocodilian.
Kuttanacaiman	K. iquitosensis	Locality IQ26 and IQ116	Middle	nearly complete skull and mandibles.	A small caiman.
Chelus	C. colombianus			Pieces of shell bones and scutes	A slightly larger species of mata mata, reaching an estimated shell length of up to a meter.
Mourasuchus	M. atopus	Locality IQ114
Paleosuchus	P. sp.
Podocnemis	P. sp.
Purussaurus	P. neivensis	Locality IQ26 and IQ114		Skull and teeth.	A giant caiman.

Correlations

Laventan

Laventan correlations in South America

Formation							Pebas					Map
Basin												align=center rowspan=17
Boreostemma	align=center		align=center		align=center		align=center		align=center		align=center		align=center		align=center		align=center		align=center
Hapalops	align=center		align=center		align=center		align=center		align=center		align=center		align=center		align=center		align=center		align=center
Miocochilius	align=center		align=center		align=center		align=center		align=center		align=center		align=center		align=center		align=center		align=center
Theosodon	align=center		align=center		align=center		align=center		align=center		align=center		align=center		align=center		align=center		align=center
Xenastrapotherium	align=center		align=center		align=center		align=center		align=center		align=center		align=center		align=center		align=center		align=center
	align=center		align=center		align=center		align=center		align=center		align=center		align=center		align=center		align=center		align=center
	align=center		align=center		align=center		align=center		align=center		align=center		align=center		align=center		align=center		align=center
	align=center		align=center		align=center		align=center		align=center		align=center		align=center		align=center		align=center		align=center		align=center
Rodents	align=center		align=center		align=center		align=center		align=center		align=center		align=center		align=center		align=center		align=center		align=center
Birds	align=center		align=center		align=center		align=center		align=center		align=center		align=center		align=center		align=center		align=center
Terror birds	align=center		align=center		align=center		align=center		align=center		align=center		align=center		align=center		align=center		align=center		align=center
Reptiles	align=center		align=center		align=center		align=center		align=center		align=center		align=center		align=center		align=center		align=center		align=center
	align=center		align=center		align=center		align=center		align=center		align=center		align=center		align=center		align=center		align=center		align=center
	align=center		align=center		align=center		align=center		align=center		align=center		align=center		align=center		align=center		align=center		align=center
Insects	align=center		align=center		align=center		align=center		align=center		align=center		align=center		align=center		align=center		align=center		align=center
	Fluvial			Fluvio-deltaic		Fluvio-lacustrine		Fluvio-deltaic			Fluvial
Volcanic	Yes

Huayquerian

Huayquerian correlations in South America

Formation											Pebas						Map
Basin																	align=center rowspan=17
Cardiatherium	align=center		align=center		align=center		align=center		align=center		align=center		align=center		align=center		align=center		align=center		align=center		align=center		align=center		align=center		align=center		align=center
Lagostomus	align=center		align=center		align=center		align=center		align=center		align=center		align=center		align=center		align=center		align=center		align=center		align=center		align=center		align=center		align=center
Macroeuphractus	align=center		align=center		align=center		align=center		align=center		align=center		align=center		align=center		align=center		align=center		align=center		align=center		align=center		align=center		align=center
Proeuphractus	align=center		align=center		align=center		align=center		align=center		align=center		align=center		align=center		align=center		align=center		align=center		align=center		align=center		align=center		align=center		align=center
Pronothrotherium	align=center		align=center		align=center		align=center		align=center		align=center		align=center		align=center		align=center		align=center		align=center		align=center		align=center		align=center		align=center		align=center
Pseudotypotherium	align=center		align=center		align=center		align=center		align=center		align=center		align=center		align=center		align=center		align=center		align=center		align=center		align=center		align=center		align=center		align=center
Thylacosmilus	align=center		align=center		align=center		align=center		align=center		align=center		align=center		align=center		align=center		align=center		align=center		align=center		align=center		align=center		align=center
Xotodon	align=center		align=center		align=center		align=center		align=center		align=center		align=center		align=center		align=center		align=center		align=center		align=center		align=center		align=center		align=center		align=center
	align=center		align=center		align=center		align=center		align=center		align=center		align=center		align=center		align=center		align=center		align=center		align=center		align=center		align=center		align=center		align=center
	align=center		align=center		align=center		align=center		align=center		align=center		align=center		align=center		align=center		align=center		align=center		align=center		align=center		align=center		align=center		align=center
Rodents	align=center		align=center		align=center		align=center		align=center		align=center		align=center		align=center		align=center		align=center		align=center		align=center		align=center		align=center		align=center		align=center
Reptiles	align=center		align=center		align=center		align=center		align=center		align=center		align=center		align=center		align=center		align=center		align=center		align=center		align=center		align=center		align=center		align=center
Birds	align=center		align=center		align=center		align=center		align=center		align=center		align=center		align=center		align=center		align=center		align=center			align=center		align=center		align=center		align=center
Terror birds	align=center		align=center		align=center		align=center		align=center		align=center		align=center		align=center		align=center		align=center		align=center		align=center		align=center		align=center		align=center		align=center
	align=center		align=center		align=center		align=center		align=center		align=center		align=center		align=center		align=center		align=center		align=center		align=center		align=center		align=center		align=center		align=center
	Aeolian-fluvial	Fluvio-deltaic			Fluvial						Fluvio-lacustrine	Fluvial			Fluvio-lacustrine	Fluvio-deltaic
Volcanic						Yes

References

Bibliography

Further reading

• • Marcos C.Bissaro-Júnior, Leonardo Kerber, James L.Crowley, Ana M.Ribeiro, Renato P.Ghilardi, Edson Guilherme, Francisco R.Negri, Jonas P.Souza Filho, Annie S.Hsiou: "Detrital zircon U–Pb geochronology constrains the age of Brazilian Neogene deposits from Western Amazonia." Palaeogeography, Palaeoclimatology, Palaeoecology Volume 516, 15 February 2019, Pages 64–70

Notes and References

1. Wesselingh et al., 2006
2. Sala Gismondi et al., 2006
3. Rasia, Luciano L.; Candela, Adriana M. (2018-05-19). "Reappraisal of the giant caviomorph rodent Phoberomys burmeisteri (Ameghino, 1886) from the late Miocene of northeastern Argentina, and the phylogeny and diversity of Neoepiblemidae". Historical Biology. 30 (4): 486–495. doi:10.1080/08912963.2017.1294168. ISSN 0891-2963. S2CID 90381892.