La Colonia Formation

La Colonia Formation
Stratigraphic range: Maastrichtian-Danian ~69–64 Ma PreꞒ Ꞓ O S D C P T J K Pg N ↓
An outcrop of the La Colonia Formation on the Somún Curá plateau that is the type locality of Chubutinectes. Photographed in 2009.
Type	Geological formation
Sub-units	Lower, Middle and Upper members
Underlies	El Buitre & Sarmiento Formations
Overlies	Cerro Barcino & Paso del Sapo Formations
Thickness	Up to 210–240 m (690–790 ft) Thinning to 17 m (56 ft) around Telsen
Lithology
Primary	Siltstone
Other	Sandstone, claystone, conglomerate
Location
Coordinates	43°00′S 67°30′W / 43.0°S 67.5°W / -43.0; -67.5
Approximate paleocoordinates	45°42′S 53°48′W / 45.7°S 53.8°W / -45.7; -53.8
Region	Chubut Province
Country	Argentina
Extent	Cañadón Asfalto Basin
Type section
Named for	Sierra La Colonia
La Colonia Formation (Argentina)

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] A further study in 2021 utilizing magnetostratigraphy and palynological data provided an age of 69 to 64 million years ago.^[3]

Description

Paleogeography of the Late Cretaceous with La Colonia Formation indicated

It is divided up into three distinct facies, the first is up to 16 metres (52 ft) thick and consists of conglomerate, the second is by far the thickest at over 100 metres (330 ft), consists of siltstone and claystone, with interbeds of claystone/shale and sandstone, the third is less than 10 metres (33 ft) thick and consists of clay, and probably represents a nearshore marine environment.^[4]

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.^[5]

Fossil content

Speculative restoration of a La Colonia Formation environment

Color key Taxon Reclassified taxon Taxon falsely reported as present Dubious taxon or junior synonym Ichnotaxon Ootaxon Morphotaxon		Notes Uncertain or tentative taxa are in small text; crossed out taxa are discredited.

Turtles

Turtles from the La Colonia Formation
Genus	Species	Location	Stratigraphic position	Material	Notes	Images
Calvarichelys[6]	C. coloniensis	Norte de Cerro Bayo 2	Middle levels	Skull and lower jaw; postcranial remains	A chelid
Patagoniaemys[4]	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."[7]	A meiolaniform
Yaminuechelys[8]	aff.Y. gasparinii[4]	Norte de Cerro Bayo 1 Norte de Cerro Bayo 2 Cerro Bosta		"Three specimens formed only by postcranial remains (mainly shell fragments)"
	Y. sulcipeculiaris

Fish

Fish from the La Colonia Formation
Genus	Species	Location	Stratigraphic position	Material	Notes	Images
Metaceratodus[9]	M. baibianorum	Norte de Cerro Bayo 1			A ceratodontid lungfish

Plesiosaurs

Plesiosaurs from the La Colonia Formation
Genus	Species	Location	Stratigraphic position	Material	Notes	Images
Chubutinectes[10]	C. carmeloi			Several vertebrae, ribs, partial pectoral and pelvic girdles, arm and leg bones, and gastroliths	An elasmosaurid	Kawanectes Sulcusuchus
Elasmosauridae indet.[4]	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[11]	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[4]	S. erraini	Cerro Bosta		"part of skull and mandible"	A polycotylid

Dinosaurs

Ornithischians

Ornithischians from the La Colonia Formation
Genus	Species	Location	Stratigraphic position	Material	Notes	Images
Ankylosauria indet.[4]	Indeterminate	Norte de Cerro Bayo 2		An osteoderm
Unnamed Parankylosauria[12][13]	Unnamed			Multiple specimens including cranial and postcranial remains, representing much of the complete skeleton[12][13]	An unnamed and undescribed parankylosaur with a 'cudgel-like' tail weapon distinct from that of Stegouros[12][13]
Hadrosauroidea indet.[4]	Indeterminate	Norte de Cerro Bayo 2		Metatarsal fragment and two vertebral fragments
Unnamed Hadrosauridae[13]	Unnamed			An articulated skeleton with a complete skull[13]	An unnamed and undescribed hadrosaurid related to other South American kritosaurins, representing the most complete hadrosaur from the continent[13]

Sauropods

Sauropods from the La Colonia Formation
Genus	Species	Location	Stratigraphic position	Material	Notes	Images
Somphospondyli indet.[4]	Indeterminate	Norte de Cerro Bayo 2		"Two fragmentary caudal vertebrae"
Titanomachya[14]	T. gimenezi	Norte de Cerro Bayo 2		"Partial postcranial skeleton"	A saltasauroid titanosaur sauropod with possible affinities to the Saltasaurinae[13]

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"[15]	An abelisaurid[16][17]	Carnotaurus Koleken
Enantiornithes indet.[18]	Indeterminate			A distal humerus
Koleken[4][19]	K. inakayali	Norte de Cerro Bayo 1		"Quite complete and partially articulated skeleton"	An abelisaurid.
Neornithes indet.[20]	Indeterminate			A distal ulna	Similar to Anseriformes
Theropoda indet.[4]	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.^[21]

Mammals of the La Colonia Formation
Genus	Species	Location	Stratigraphic position	Material	Notes	Images
Argentodites	A. coloniensis[22]				A possible gondwanatherian or multituberculate
Coloniatherium	C. cilinskii[23]				A meridiolestidan
Ferugliotherium	F. windhauseni[22]				A possible gondwanatherian or multituberculate
Reigitherium	R. bunodontum[24]				A meridiolestidan

Snakes

Fossils of madtsoiids, and perhaps boids, have been found in the formation.^[25]

Snakes from the La Colonia Formation
Genus	Species	Location	Stratigraphic position	Material	Notes	Images
Alamitophis	A. argentinus[25]			Trunk vertebra	A madtsoiid snake
Eomadtsoia	E. ragei[26]				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

1. Weishampel et al., 2004, pp.600-604
2. Rauhut, 2003
3. Clyde, W.C.; Krause, J.M.; De Benedetti, F.; Ramezani, J.; Cúneo, N.R.; Gandolfo, M.A.; Haber, P.; Whelan, C.; Smith, T. (October 2021). "New South American record of the Cretaceous–Paleogene boundary interval (La Colonia Formation, Patagonia, Argentina)". Cretaceous Research. 126 104889. Bibcode:2021CrRes.12604889C. doi:10.1016/j.cretres.2021.104889.
4. Gasparini, Zulma; Sterli, Juliana; Parras, Ana; O'Gorman, José Patricio; Salgado, Leonardo; Varela, Julio; Pol, Diego (May 2015). "Late Cretaceous reptilian biota of the La Colonia Formation, central Patagonia, Argentina: Occurrences, preservation and paleoenvironments". Cretaceous Research. 54: 154–168. Bibcode:2015CrRes..54..154G. doi:10.1016/j.cretres.2014.11.010. hdl:11336/19244.
5. Gandolfo, Maria A.; Cuneo, Ruben N. (February 2005). "Fossil Nelumbonaceae from the La Colonia Formation (Campanian–Maastrichtian, Upper Cretaceous), Chubut, Patagonia, Argentina". Review of Palaeobotany and Palynology. 133 (3–4): 169–178. Bibcode:2005RPaPa.133..169G. doi:10.1016/j.revpalbo.2004.09.007.
6. Oriozabala, Carolina; de la Fuente, Marcelo S.; Holley, J. Alfredo; Sterli, Juliana (2025). "A new chelid turtle (Testudines, Pleurodira) from the Cretaceous of Patagonia, Argentina". Papers in Palaeontology. 11 (2) e70006. Bibcode:2025PPal...11E0006O. doi:10.1002/spp2.70006.
7. Sterli & De la Fuente, 2011
8. 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 104197. Bibcode:2020CrRes.10604197O. doi:10.1016/j.cretres.2019.104197.
9. 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. Bibcode:2020JVPal..40E9640P. doi:10.1080/02724634.2020.1769640.
10. O'Gorman, José P.; Carignano, Ana Paula; Calvo-Marcilese, Lydia; Pérez Panera, Juan Pablo (December 2023). "A new elasmosaurid (Sauropterygia, Plesiosauria) from the upper levels of the La Colonia Formation (upper Maastrichtian), Chubut Province, Argentina". Cretaceous Research. 152 105674. Bibcode:2023CrRes.15205674O. doi:10.1016/j.cretres.2023.105674.
11. O'Gorman, 2019
12. Becerra, Marcos G; Pol, Diego; Carballido, Jose; Aspromonte, Franco; Pittman, Michael (November 2023). "Parankylosaurian weaponry gets even stranger: new ankylosaur remains from the La Colonia Formation (Maastrichtian-Danian) represent the most complete record in Argentina". Conicet. Retrieved October 5, 2025.
13. Pol, Diego; Becerra, Marcos Gabriel; Carballido, Jose Luis; Krause, Marcelo; Baiano, Mattia; Pittman, Michael (2023). "New Dinosaur Discoveries inteh La Colonia Formation: Insights Into the Late Cretaceous Fauna of Patagonia Before the K-PG Extinction Event". Conicet. Retrieved October 5, 2025.
14. 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. 37 (4): 792–811. doi:10.1080/08912963.2024.2332997.
15. "Table 3.1," in Weishampel et al., 2004, p.49
16. Rauhut, 2004
17. Leanza et al., 2004, p.72
18. Lawver, Daniel R.; Debee, Aj M.; Clarke, Julia A.; Rougier, Guillermo W. (December 2011). "A New Enantiornithine Bird from the Upper Cretaceous La Colonia Formation of Patagonia, Argentina". Annals of Carnegie Museum. 80 (1): 35–42. Bibcode:2011AnCM...80...35L. doi:10.2992/007.080.0104.
19. Pol, Diego; Baiano, Mattia Antonio; Černý, David; Novas, Fernando; Cerda, Ignacio A. (21 May 2024). "A new abelisaurid dinosaur from the end Cretaceous of Patagonia and evolutionary rates among the Ceratosauria". Cladistics. 40 (3): 307–356. doi:10.1111/cla.12583. PMID 38771085.
20. 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. 105595. Bibcode:2023CrRes.15005595A. doi:10.1016/j.cretres.2023.105595.
21. Rougier et al., 2009, p.225
22. Gurovich, Y.; Beck, R. (2009). "The phylogenetic affinities of the enigmatic mammalian clade Gondwanatheria". Journal of Mammalian Evolution. 16 (1): 25–49. doi:10.1007/s10914-008-9097-3.
23. Rougier, G.W.; Forasiepi, A.M.; Hill, R.V.; Novacek, M. (2009). "New mammalian remains from the Late Cretaceous La Colonia Formation, Patagonia, Argentina". Acta Palaeontologica Polonica. 54 (2): 195–212. doi:10.4202/app.2006.0026.
24. Rougier, G. W.; Turazzinni, G. F.; Cardozo, M. S.; Harper, T.; Lires, A. I.; Canessa, L. A. (2021). "New Specimens of Reigitherium bunodontum from the Late Cretaceous La Colonia Formation, Patagonia, Argentina and Meridiolestidan Diversity in South America". Journal of Mammalian Evolution. 28 (4): 1051–1081. doi:10.1007/s10914-021-09585-2.
25. Albino, Adriana M. (2000). "New record of snakes from the Cretaceous of Patagonia (Argentina)". Geodiversitas. 22 (2): 247–253.
26. 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. Bibcode:2019CRPal..18..771G. doi:10.1016/j.crpv.2019.09.003. hdl:11336/139595.

Bibliography

• Gasparini, Zulma; Sterli, Juliana; Parras, Ana; O'Gorman, José Patricio; Salgado, Leonardo; Varela, Julio; Pol, Diego (May 2015). "Late Cretaceous reptilian biota of the La Colonia Formation, central Patagonia, Argentina: Occurrences, preservation and paleoenvironments". Cretaceous Research. 54: 154–168. Bibcode:2015CrRes..54..154G. doi:10.1016/j.cretres.2014.11.010. hdl:11336/19244.
• Gandolfo, Maria A.; Cuneo, Ruben N. (February 2005). "Fossil Nelumbonaceae from the La Colonia Formation (Campanian–Maastrichtian, Upper Cretaceous), Chubut, Patagonia, Argentina". Review of Palaeobotany and Palynology. 133 (3–4): 169–178. Bibcode:2005RPaPa.133..169G. doi:10.1016/j.revpalbo.2004.09.007.
• Patricio O’Gorman, JosÉ (2 January 2020). "First record of Kawanectes lafquenianum (Plesiosauria, Elasmosauridae) from the La Colonia Formation of Argentina, with comments on the mandibular morphology of elasmosaurids". Alcheringa: An Australasian Journal of Palaeontology. 44 (1): 176–193. Bibcode:2020Alch...44..176P. doi:10.1080/03115518.2019.1687754.
• Leanza, Héctor A; Apesteguı́a, Sebastián; Novas, Fernando E; de la Fuente, Marcelo S (February 2004). "Cretaceous terrestrial beds from the Neuquén Basin (Argentina) and their tetrapod assemblages". Cretaceous Research. 25 (1): 61–87. Bibcode:2004CrRes..25...61L. doi:10.1016/j.cretres.2003.10.005.
• Rauhut, Oliver W. M. (10 December 2004). "Provenance and anatomy of Genyodectes serus , a large-toothed ceratosaur (Dinosauria: Theropoda) from Patagonia". Journal of Vertebrate Paleontology. 24 (4): 894–902. doi:10.1671/0272-4634(2004)024[0894:PAAOGS]2.0.CO;2.
• Rauhut, Oliver W.M.; Cladera, Gerardo; Vickers-Rich, Patricia; Rich, Thomas H. (October 2003). "Dinosaur remains from the Lower Cretaceous of the Chubut Group, Argentina". Cretaceous Research. 24 (5): 487–497. Bibcode:2003CrRes..24..487R. doi:10.1016/S0195-6671(03)00067-3.
• Rougier, Guillermo W.; Chornogubsky, Laura; Casadio, Silvio; Arango, Natalia Paéz; Giallombardo, Andres (February 2009). "Mammals from the Allen Formation, Late Cretaceous, Argentina". Cretaceous Research. 30 (1): 223–238. Bibcode:2009CrRes..30..223R. doi:10.1016/j.cretres.2008.07.006. hdl:11336/103413.
• Sterli, Juliana; De La Fuente, Marcelo S. (January 2011). "A new turtle from the La Colonia Formation (Campanian–Maastrichtian), Patagonia, Argentina, with remarks on the evolution of the vertebral column in turtles". Palaeontology. 54 (1): 63–78. Bibcode:2011Palgy..54...63S. doi:10.1111/j.1475-4983.2010.01002.x.
• Weishampel, David B.; Dodson, Peter; Osmólska, Halszka (2004). The Dinosauria, Second Edition. University of California Press. ISBN 978-0-520-94143-4.

Further reading

• Albino, Adriana María (2000). "New record of snakes from the Cretaceous of Patagonia (Argentina)". Geodiversitas. 22 (2): 247–253.
• Cúneo, N. Rubén; Hermsen, Elizabeth J.; Gandolfo, Maria A. (2013). "Regnellidium (Salviniales, Marsileaceae) Macrofossils and Associated Spores from the Late Cretaceous of South America". International Journal of Plant Sciences. 174 (3): 340–349. Bibcode:2013IJPlS.174..340C. doi:10.1086/668811. JSTOR 10.1086/668811.
• O'Gorman, José Patricio; Salgado, Leonardo; Cerda, Ignacio Alejandro; Gasparini, Zulma (March 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. Bibcode:2013CrRes..40..212O. doi:10.1016/j.cretres.2012.07.004. hdl:11336/7325.
• O’gorman, José P.; Gasparini, Zulma (June 2013). "Revision of Sulcusuchus erraini (Sauropterygia, Polycotylidae) from the Upper Cretaceous of Patagonia, Argentina". Alcheringa: An Australasian Journal of Palaeontology. 37 (2): 163–176. Bibcode:2013Alch...37..163O. doi:10.1080/03115518.2013.736788. hdl:11336/2489.
• Harper, Tony; Parras, Ana; Rougier, Guillermo W. (December 2019). "Reigitherium (Meridiolestida, Mesungulatoidea) an Enigmatic Late Cretaceous Mammal from Patagonia, Argentina: Morphology, Affinities, and Dental Evolution". Journal of Mammalian Evolution. 26 (4): 447–478. doi:10.1007/s10914-018-9437-x.
• Kielan-Jaworowska, Z.; Ortiz-Jaureguizar, E.; Vieytes, C.; Pascual, R.; Goin, F. J. (2007). "First cimolodontan multituberculate mammal from South America" (PDF). Acta Palaeontologica Polonica. 52 (2): 257–262.