La Colonia Formation Explained

La Colonia Formation
Type:	Geological formation
Period:	Maastrichtian
Age:	Campanian-Maastrichtian ~
Prilithology:	Siltstone
Otherlithology:	Sandstone, claystone, conglomerate
Namedfor:	Sierra La Colonia
Region:	Chubut Province
Country:	Argentina
Coordinates:	-43°N -67.5°W
Paleocoordinates:	-45.7°N -53.8°W
Subunits:	Lower, Middle and Upper members
Underlies:	El Buitre & Sarmiento Formations
Overlies:	Cerro Barcino & Paso del Sapo Formations
Thickness:	Up to 210- Thinning to 17m (56feet) around Telsen
Extent:	Cañadón Asfalto Basin

The La Colonia Formation is a geological formation in Argentina whose strata date back to the Late Cretaceous. Dinosaur remains are among the fossils that have been recovered from the formation.^[1]

Originally thought to be Campanian (c.73-72 million years ago) in age or earlier, studies of underlying formations have made a Maastrichtian (72 - 66 million years ago) age more likely.^[2]

Description

It is divided up into three distinct facies, the first is up to 16m (52feet) thick and consists of conglomerate, the second is by far the thickest at over 100m (300feet), consists of siltstone and claystone, with interbeds of claystone/shale and sandstone, the third is less than 10m (30feet) thick and consists of clay, and probably represents a nearshore marine environment.^[3]

The paleoflora was known for its aquatic components, Paleoazolla and Regnellidium. However, recent paleobotanical discoveries at the Cañadón del Irupé locality have revealed the presence of a more diverse range of plants associated with these water bodies, including pteridophytes, gymnosperms, and various angiosperms. Among these are fossil leaves and fruits assignable to Nelumbonaceae.^[4]

Fossil content

Turtles

Turtles from the La Colonia Formation
Genus	Species	Location	Stratigraphic position	Material	Notes	Images
Chelidae gen. nov.	sp. nov.	Norte de Cerro Bayo 2		Skull and lower jaw; postcranial remains	Represents a new genus of chelid
Patagoniaemys	P. gasparinae	Buitre Chico in and around Norte de Cerro Bayo 2 Cerro Bosta		"skull fragments and several postcranial elements including a nearly complete vertebral column."^[5]	A meiolaniform
aff. Yaminuechelys	Y. gasparinii	Norte de Cerro Bayo 2 Cerro Bosta		"Three specimens formed only by postcranial remains (mainly shell fragments)"
Yaminuechelys^[6]	Y. sulcipeculiaris	Norte de Cerro Bayo 1 Cerro Bosta

Plesiosaurs

Plesiosaurs from the La Colonia Formation
Genus	Species	Location	Stratigraphic position	Material	Notes	Images
Chubutinectes^[8]	C. carmeloi			Several vertebrae, ribs, partial pectoral and pelvic girdles, arm and leg bones, and gastroliths	An elasmosaurid
Elasmosauridae	Indeterminate	Norte de Cerro Bayo 1 Cerro Bosta		"three postcranial specimens that preserve cervical, dorsal and caudal vertebrae, ribs and gastroliths and three vertebrae without collection number"
Kawanectes^[9]	K. lafquenianum			"an incomplete mandible, nine cervical vertebrae, 14 dorsal vertebrae, three sacral vertebrae and five caudal vertebrae, and almost complete left fore limb, the isolated right humerus, both femora, ilia, pubes and the right ischium"	An elasmosaurid
Sulcusuchus	S. erraini	Cerro Bosta		"part of skull and mandible"	A polycotylid

Dinosaurs

Ornithiscians

Ornithischians from the La Colonia Formation
Genus	Species	Location	Stratigraphic position	Material	Notes	Images
Ankylosauria	Indeterminate	Norte de Cerro Bayo 2		An osteoderm
Hadrosauroidea	Indeterminate	Norte de Cerro Bayo 2		Metatarsal fragment and two vertebral fragments

Sauropods

Sauropods from the La Colonia Formation
Genus	Species	Location	Stratigraphic position	Material	Notes	Images
Somphospondyli	Indeterminate	Norte de Cerro Bayo 2		"Two fragmentary caudal vertebrae"
Titanomachya^[10]	T. gimenezi	Norte de Cerro Bayo 2		"Partial postcranial skeleton"	A titanosaur sauropod

Theropods

Theropods from the La Colonia Formation
Genus	Species	Location	Stratigraphic position	Material	Notes	Images
Carnotaurus	C. sastrei	Pocho Sastre		"Nearly complete skeleton and skull"^[11]	An abelisaurid^[12] ^[13]
Enantiornithine^[14]	Indeterminate			A distal humerus
Koleken^[15]	K. inakayali	Norte de Cerro Bayo 1		"Quite complete and partially articulated skeleton"	An abelisaurid.
Neornithes^[16]	Indeterminate			A distal ulna
Theropoda	Indeterminate	Norte de Cerro Bayo 2		"Metatarsal fragments of a single individual"

Mammals

Over 300 mammal specimens have been found in the La Colonia Formation.^[17]

Mammals of the La Colonia Formation
Genus	Species	Location	Stratigraphic position	Material	Notes	Images
Argentodites	A. coloniensis				A possible gondwanatherian or multituberculate
Coloniatherium	C. cilinskii^[18]				A meridiolestidan
Ferugliotherium	F. windhauseni^[19]				A possible gondwanatherian or multituberculate
Reigitherium	R. bunodontum^[20]				A meridiolestidan

Snakes

Fossils of madtsoiids, and perhaps boids, have been found in the formation.^[21]

Snakes from the La Colonia Formation
Genus	Species	Location	Stratigraphic position	Material	Notes	Images
Alamitophis	A. argentinus			Trunk vertebra	A madtsoiid snake
Eomadtsoia	E. ragei^[22]				A madtsoiid Snake

See also

• List of dinosaur-bearing rock formations
• Allen Formation, Campanian to Maastrichtian fossiliferous formation of the Neuquén Basin
• Angostura Colorada Formation, Campanian to Maastrichtian fossiliferous formation of the North Patagonian Massif
• Colorado Formation, Campanian to Maastrichtian fossiliferous formation of the Colorado Basin
• Lago Colhué Huapí Formation, Campanian to Maastrichtian fossiliferous formation of the Golfo San Jorge Basin

References

Bibliography

Further reading

• A. M. Albino. 2000. New record of snakes from the Cretaceous of Patagonia (Argentina). Geodiversitas 22(2):247-253
• N. R. Cúneo, E. J. Hermsen, and M. A. Gandolfo. 2013. Regnellidium (Salviniales, Marsileaceae) macrofossils and associated spores from the Late Cretaceous of South America. PloSOne 174(3):340-349
• J. P. O'Gorman, L. Salgado, I. A. Cerda and Z. Gasparini. 2013. First record of gastroliths associated with elasmosaur remains from La Colonia Formation (Campanian–Maastrichtian), Chubut, Patagonia Argentina, with comments on the probable depositional palaeoenvironment of the source of the gastroliths. Cretaceous Research 40:212-217
• J. O'Gorman and Z. Gasparini. 2013. Revision of Sulcusuchus erraini (Sauropterygia, Polycotylidae) from the Upper Cretaceous of Patagonia, Argentina. Alcheringa 37(2):163-176
• T. Harper, A. Parras, and G. W. Rougier. 2018. Reigitherium (Meridiolestida, Mesungulatoidea) an Enigmatic Late Cretaceous Mammal from Patagonia, Argentina: Morphology, Affinities, and Dental Evolution. Journal of Mammalian Evolution
• Z. Kielan-Jaworowska, E. Ortiz-Jaureguizar, C. Vieytes, R. Pascual, and F. J. Goin. 2007. First cimolodontan multituberculate mammal from South America. Acta Palaeontologica Polonica 52(2):257-262

Notes and References

1. Weishampel et al., 2004, pp.600-604
2. Rauhut, 2003
3. Gasparini . Zulma . Sterli . Juliana . Parras . Ana . O'Gorman . José Patricio . Salgado . Leonardo . Varela . Julio . Pol . Diego . Late Cretaceous reptilian biota of the La Colonia Formation, central Patagonia, Argentina: Occurrences, preservation and paleoenvironments . Cretaceous Research . May 2015 . 54 . 154–168 . 10.1016/j.cretres.2014.11.010. 2015CrRes..54..154G . 11336/19244 . free .
4. Gandolfo . Maria A. . Cuneo . Ruben N. . Fossil Nelumbonaceae from the La Colonia Formation (Campanian–Maastrichtian, Upper Cretaceous), Chubut, Patagonia, Argentina . Review of Palaeobotany and Palynology . February 2005 . 133 . 3–4 . 169–178 . 10.1016/j.revpalbo.2004.09.007. 2005RPaPa.133..169G .
5. Sterli & De la Fuente, 2011
6. Carolina Oriozabala . Juliana Sterli . Marcelo S. De La Fuente . 2020 . New species of the long-necked chelid Yaminuechelys from the Upper Cretaceous (Campanian–Maastrichtian) of Chubut, Argentina . Cretaceous Research . 106 . Article 104197 . 10.1016/j.cretres.2019.104197 . 2020CrRes.10604197O . 201336536 .
7. Karen M. Panzeri . Soledad Gouiric Cavalli . Nahuel A. Muñoz . Alberto L. Cione . 2020 . Metaceratodus baibianorum, a new dipnoan species from the Upper Cretaceous of southern South America supported by traditional and geometric morphometric analyses . Journal of Vertebrate Paleontology . 40 . 2 . e1769640 . 10.1080/02724634.2020.1769640 . 2020JVPal..40E9640P . 222210313 .
8. O’Gorman . José P. . Carignano . Ana Paula . Calvo-Marcilese . Lydia . Pérez Panera . Juan Pablo . 2023-08-10 . A new elasmosaurid (Sauropterygia, Plesiosauria) from the upper levels of the La Colonia Formation (upper Maastrichtian), Chubut Province, Argentina . Cretaceous Research . 152 . en . 105674 . 10.1016/j.cretres.2023.105674 . 2023CrRes.15205674O . 0195-6671.
9. O'Gorman, 2019
10. Pérez-Moreno . A. . Salgado . L. . Carballido . J. L. . Otero . A. . Pol . D. . 2024 . A new titanosaur from the La Colonia Formation (Campanian-Maastrichtian), Chubut Province, Argentina . Historical Biology: An International Journal of Paleobiology . 1–20 . 10.1080/08912963.2024.2332997 . free.
11. "Table 3.1," in Weishampel et al., 2004, p.49
12. Rauhut, 2004
13. Leanza et al., 2004, p.72
14. 10.2992/007.080.0104 . 80 . 1 . 35–42 . Lawver . Daniel R. . Debee. Aj M. . Clarke. Julia A. . Rougier. Guillermo W. . A New Enantiornithine Bird from the Upper Cretaceous La Colonia Formation of Patagonia, Argentina . Annals of Carnegie Museum . January 1, 2011 . 85015365 .
15. Pol . Diego . Baiano . Mattia Antonio . Černý . David . Novas . Fernando . Cerda . Ignacio A. . A new abelisaurid dinosaur from the end Cretaceous of Patagonia and evolutionary rates among the Ceratosauria . Cladistics. 21 May 2024 . 40 . 3 . 307–356 . 10.1111/cla.12583 . free . 38771085 .
16. Acosta Hospitaleche . C. . O'Gorman . J. P. . Panzeri . K. M. . 2023 . A new Cretaceous bird from the Maastrichtian La Colonia Formation (Patagonia, Argentina) . Cretaceous Research . 150 . 105595 . 10.1016/j.cretres.2023.105595 . 2023CrRes.15005595A . 259059084 .
17. Rougier et al., 2009, p.225
18. Rougier . G.W. . Forasiepi . A.M. . Hill . R.V. . Novacek . M. . New mammalian remains from the Late Cretaceous La Colonia Formation, Patagonia, Argentina . 10.4202/app.2006.0026 . Acta Palaeontologica Polonica . 54 . 2 . 195–212 . 2009 . free .
19. Gurovich . Y. . Beck . R. . 10.1007/s10914-008-9097-3 . The phylogenetic affinities of the enigmatic mammalian clade Gondwanatheria . Journal of Mammalian Evolution . 16. 1. 25–49 . 2009. 42799370 .
20. Rougier . G. W. . Turazzinni . G. F. . Cardozo . M. S. . Harper . T. . Lires . A. I. . Canessa . L. A. . New Specimens of Reigitherium bunodontum from the Late Cretaceous La Colonia Formation, Patagonia, Argentina and Meridiolestidan Diversity in South America . Journal of Mammalian Evolution . 2021 . 28 . 4 . 1051–1081 . 10.1007/s10914-021-09585-2. 254704047 .
21. Albino . Adriana M. . 2000 . New record of snakes from the Cretaceous of Patagonia (Argentina) . Geodiversitas . 22 . 2 . 247–253 .
22. Raúl O. Gómez . Fernando F. Garberoglio . Guillermo W. Rougier . 2019 . A new Late Cretaceous snake from Patagonia: Phylogeny and trends in body size evolution of madtsoiid snakes . Comptes Rendus Palevol . 18 . 7 . 771–781 . 10.1016/j.crpv.2019.09.003 . 2019CRPal..18..771G . 11336/139595 . 213774502 . free .