Pebas Formation

Pebas Formation
Stratigraphic range: Early Aquitanian-Tortonian (Colhuehuapian-Huayquerian) ~21–8 Ma PreꞒ Ꞓ O S D C P T J K Pg N
The Pebas Mega-Wetland (or Lake Pebas), on the western side of this map, corresponds to the Pebas Formation
Underlies	Marañón Formation
Overlies	Chambira Formation
Area	1,000,000 km2 (390,000 sq mi)
Thickness	~350–1,074 m (1,148–3,524 ft)
Lithology
Primary	Siltstone, mudstone
Other	Coal/lignite
Location
Coordinates	7°24′S 75°00′W / 7.4°S 75.0°W / -7.4; -75.0
Approximate paleocoordinates	8°24′S 70°36′W / 8.4°S 70.6°W / -8.4; -70.6
Region	Amazon Basin
Country	Brazil  Colombia  Ecuador  Peru
Type section
Named for	Pebas District

The Pebas Formation is a lithostratigraphic unit of Miocene age, found in western Amazonia. The formation extends over 1,000,000 square kilometres (390,000 sq mi), 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[edit]

Fish[edit]

Insects[edit]

Taxa	Species	Locality	Stratigraphic position	Material	Notes	Images
Macroteleia [4]	M. yaguarum				A parasitoid wasp.
Sycorax	S. peruensis				Relatives of moth flies and sand flies.

Mammals[edit]

Taxa	Species	Locality	Stratigraphic position	Material	Notes	Images
Dinomyidae [3]	D. sp.				A hystricognath rodent.
Octodontoidea	Indeterminate.				A hystricognath rodent.
Neoepiblema[5]	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[edit]

Taxa	Species	Locality	Stratigraphic position	Material	Notes	Images
Caiman [3][6]	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 [3][6]	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[edit]

Laventan[edit]

Laventan correlations in South America

Formation	Honda	Honda	Aisol	Cura-Mallín	Pisco	Ipururo	Pebas	Capadare	Urumaco	Inés	Paraná	Map
Basin	VSM	Honda	San Rafael	Caldera	Pisco	Ucayali	Amazon	Falcón		Venezuela	Paraná	Pebas Formation (South America)
Country	Colombia	Bolivia	Argentina	Chile	Peru			Venezuela			Argentina
Boreostemma
Hapalops
Miocochilius
Theosodon
Xenastrapotherium
Mylodontidae
Sparassodonta
Primates
Rodents
Birds
Terror birds
Reptiles
megalodon
Flora
Insects
Environments	Fluvial			Fluvio-deltaic		Fluvio-lacustrine		Fluvio-deltaic			Fluvial	Laventan volcanoclastics Laventan fauna Laventan flora
Volcanic	Yes

Huayquerian[edit]

Huayquerian correlations in South America

Formation	Cerro Azul	Ituzaingó	Paraná	Camacho	Raigón	Andalhuala	Chiquimil	Las Flores	Maimará	Palo	Pebas	Muyu	Rosa	Saldungaray	Salicas	Urumaco	Map
Basin	Colorado	Paraná				Hualfín		Tontal	Andes	Salta	Amazon	Huasi	Altiplano	BA	Velasco	Falcón	Pebas Formation (South America)
Country	Argentina			Uruguay		Argentina					Brazil  Peru	Bolivia		Argentina		Venezuela
Cardiatherium
Lagostomus
Macroeuphractus
Proeuphractus
Pronothrotherium
Pseudotypotherium
Thylacosmilus
Xotodon
Macraucheniidae
Primates
Rodents
Reptiles
Birds
Terror birds
Flora
Environments	Aeolian-fluvial	Fluvio-deltaic			Fluvial						Fluvio-lacustrine	Fluvial			Fluvio-lacustrine	Fluvio-deltaic	Huayquerian volcanoclastics Huayquerian fauna Huayquerian flora
Volcanic						Yes

References[edit]

Bibliography[edit]

• Montoya A., Diana M.; Diego Alonso O.; Alejandro Pinilla O., and José E. Arenas M. 2011. Geología de las Planchas 567, 568, 568bis, 569 and 569bis - 1:200,000, 1–187. Servicio Geológico Colombiano. Accessed 2018-06-01.
• Salas Gismondi, R.; J.J. Flynn; P. Baby; J.V. Tejada Lara; F.P. Wesselingh, and P-O. Antoine. 2015. A Miocene hyperdiverse crocodylian community reveals peculiar trophic dynamics in proto-Amazonian mega-wetlands. Proceedings of the Royal Society B: Biological Sciences 282. 20142490. Accessed 2018-05-20.
• Wesselingh, F.P.; M.C. Hoorn; J. Guerrero; M.E. Räsänen; L. Romero Pittmann, and J. Salo. 2006. The stratigraphy and regional structure of Miocene deposits in western Amazonia (Peru, Colombia and Brazil), with implications for late Neogene landscape evolution. Scripta Geologica 133. 291–322. Accessed 2017-08-15.

Further reading[edit]

• Antoine, P.; J.A. Abello; S. Adnet; A.J. Altamirano Sierra; P. Baby; G. Billet; M. Boivin; Y. Calderón, and A.R. Candela and J. Chabain, F. Corfu, D. A. Croft, M. Ganerød, C. Jaramillo, S. Klaus, L. Marivaux, R. E. Navarrete, M. J. Orliac, F. Parra, M. E. Pérez, F. Pujos, J. Rage, Anthony Ravel, Céline Robinet, Martin Roddaz, Julia Victoria Tejada Lara, Jorge Vélez-Juarbe, Frank P. Wesselingh and Rodolfo Salas Gismondi. 2016. A 60-million-year Cenozoic history of western Amazonian ecosystems in Contamana, eastern Peru. Gondwana Research 31. 30–59. Accessed 2020-03-19.
• 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 doi: 10.1016/j.palaeo.2018.11.032