Lago Colhué Huapí Formation

Lago Colhué Huapí Formation
Stratigraphic range: Campanian-Maastrichtian ~80–66 Ma PreꞒ Ꞓ O S D C P T J K Pg N
Type	Geological formation
Unit of	Chubut Group
Underlies	Laguna Palacios Formation and Río Chico Group (Salamanca Formation)
Overlies	Bajo Barreal Formation
Lithology
Primary	Tuff
Other	Sandstone
Location
Coordinates	45°36′S 68°30′W / 45.6°S 68.5°W / -45.6; -68.5
Approximate paleocoordinates	48°12′S 55°12′W / 48.2°S 55.2°W / -48.2; -55.2
Region	Central Patagonia
Country	Argentina
Extent	Golfo San Jorge Basin
Type section
Named for	Lake Colhué Huapí
Lago Colhué Huapí Formation (Argentina)

The Lago Colhué Huapí Formation is a Late Cretaceous geologic formation of the Chubut Group in the Golfo San Jorge Basin in Patagonia, Argentina. The formation, named after Lake Colhué Huapí, is overlain by the Salamanca Formation of the Río Chico Group and in some areas by the Laguna Palacios Formation.^[1]

The strata of the Lago Colhué Huapé Formation were thought to pertain to the Bajo Barreal Formation, but are now recognized as a distinct stratigraphic unit in their own right.^[1][2] The upper part of the Lago Colhué Huapí Formation has been dated to the upper Maastrichtian age of the late Cretaceous period.^[3][4]

Vertebrate paleofauna

Taxa recovered from the Lago Colhué Huapí Formation include the sauropods Aeolosaurus, and Argyrosaurus, as well as the hadrosaurid Secernosaurus and the probable elasmarian ornithopod Sektensaurus. The dubious ornithischian Notoceratops was also present.^[5][6][7][1]

Dinosaurs

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.

Ornithischians

Ornithopods from the Lago Colhué Huapí Formation
Genus	Species	Locality	Stratigraphic position	Material	Notes	Images
Notoceratops	N. bonarellii		Upper	An incomplete, toothless left dentary	A dubious genasaurian ornithischian[8]	Secernosaurus
Secernosaurus	S. koerneri	Rio Chico	Upper	A partial skeleton	A saurolophine hadrosaur
Sektensaurus	S. sanjuanboscoi	An ephemeral island	Upper	An associated partial skeleton	An elasmarian ornithopod

Sauropods

Sauropods from the Lago Colhué Huapí Formation
Genus	Species	Locality	Stratigraphic position	Material	Notes	Images
Aeolosaurus	A. colhuehuapensis	An ephemeral island	Upper	A partial skeleton	A titanosaur	Aeolosaurus Argyrosaurus
Argyrosaurus	A. superbus	La Angostura, Río Chico.	Upper	A set of limb elements (left forelimb)	A titanosaur
Elaltitan	E. lilloi	Río Senguerr bend	Lower	A partial skeleton	A titanosaur
Lithostrotia indet.[9]	Indeterminate		Middle	A partial skeleton	A titanosaur

Theropods

Theropods from the Lago Colhué Huapí Formation
Genus	Species	Locality	Stratigraphic position	Material	Notes	Images
Joaquinraptor[10]	J. casali	Valle Joaquín	Upper	A partial skeleton including skull bones, vertebrae, the pectoral girdle, and forelimb and hindlimb bones	A megaraptorid theropod	Joaquinraptor
Theropoda indet.[11]	Indeterminate	An ephemeral island, Mocha Peninsula	Upper	A manual ungual (hand claw) and possible metatarsal III	A possible megaraptoran theropod

Other reptiles

Reptiles from the Lago Colhué Huapí Formation
Genus	Species	Locality	Stratigraphic position	Material	Notes	Images
Colhuehuapisuchus	C. lunai	An ephemeral island	Upper.	A mandible (Anterior portion of mandibles)	A peirosaurid notosuchian

See also

• List of dinosaur-bearing rock formations
• List of stratigraphic units with few dinosaur genera

References

1. Casal, Allard & Foix 2015.
2. Clyde et al. 2014.
3. Vallati, De Sosa Tomas & Casal 2020.
4. Vallati, Patricia; Casal, Gabriel; Foix, Nicolás; Allard, José; Tomas, Andrea De Sosa; Calo, Marcos (August 2016). "First Report of a Maastrichtian Palynoflora from the Golfo San Jorge Basin, Central Patagonia, Argentina". Ameghiniana. 53 (4): 495–505. doi:10.5710/AMGH.28.12.2015.2948. ISSN 0002-7014.
5. Martínez et al. 2016.
6. Casal 2007.
7. Mannion & Otero 2012.
8. Fonseca, A.O.; Reid, I.J.; Venner, A.; Duncan, R.J.; Garcia, M.S.; Müller, R.T. (2024). "A comprehensive phylogenetic analysis on early ornithischian evolution". Journal of Systematic Palaeontology. 22 (1) 2346577. Bibcode:2024JSPal..2246577F. doi:10.1080/14772019.2024.2346577.
9. Ibiricu, Lucio M.; Casal, Gabriel A.; Martínez, Rubén D.; Luna, Marcelo; Svoboda, Ezequiel González; Cerda, Ignacio A. (May 2017). "New materials of lithostrotian titanosaurs (Dinosauria: Sauropoda) from the Upper Cretaceous of central Patagonia". Cretaceous Research. 73: 25–39. doi:10.1016/j.cretres.2016.12.015.
10. Ibiricu, Lucio M.; Lamanna, Matthew C.; Alvarez, Bruno N.; Cerda, Ignacio A.; Caglianone, Julieta L.; Cardozo, Noelia V.; Luna, Marcelo; Martínez, Rubén D. (2025). "Latest Cretaceous megaraptorid theropod dinosaur sheds light on megaraptoran evolution and palaeobiology". Nature Communications. 16 8298. doi:10.1038/s41467-025-63793-5.
11. Casal, Gabriel A.; Martínez, Rubén D.; Luna, Marcelo; Ibiricu, Lucio M. (May 7, 2016). "Ordenamiento y caracterización faunística del Cretácico Superior del Grupo Chubut, Cuenca del Golfo San Jorge, Argentina" (PDF). Revista Brasileira de Paleontologia. 19 (1): 53–70. doi:10.4072/rbp.2016.1.05.

Bibliography

• Casal, Gabriel A.; Allard, José O.; Foix, Nicolás (March 2015). "Análisis estratigráfico y paleontológico del cretácico superior en la cuenca del golfo San Jorge: nueva unidad litoestratigráfica para el grupo Chubut" [Stratigraphic and paleontological analysis of the Upper Cretaceous in the San Jorge Gulf Basin: a new lithostratigraphic unit for the Chubut Group]. Revista de la Asociación Geológica Argentina (in Spanish). 72 (1): 77–95. hdl:11336/111016.
• Casal, Gabriel (30 April 2007). "Aeolosaurus colhuehuapensis sp. nov. (Sauropoda, Titanosauria) de la Formación Bajo Barreal, Cretácico superior de Argentina" [Aeolosaurus colhuehuapensis sp. nov.(Sauropoda, Titanosauria) from the Lower Barreal Formation, upper Cretaceous of Argentina]. Revista Brasileira de Paleontologia (in Spanish). 10 (1): 53–62. Bibcode:2007RvBrP..10...53C. doi:10.4072/rbp.2007.1.05.
• Clyde, W.C.; Wilf, P.; Slingerland, Iglesias A.; Barnum, T.; Bijl, P.K. (2014), "New age constraints for the Salamanca Formation and lower Río Chico Group in the western San Jorge Basin, Patagonia, Argentina: implications for Cretaceous—Paleogene extinction recovery and land mammal age correlations", Geological Society of America Bulletin, 126 (3–4): 289–306, Bibcode:2014GSAB..126..289C, doi:10.1130/B30915.1, hdl:11336/80135
• Cortés, José María (1986). Estratigrafía y tectónica de la región central de la Provincia de Chubut, República Argentina [Stratigraphy and tectonics of the central region of Chubut Province, Argentina] (Thesis) (in Spanish). Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. hdl:20.500.12110/tesis_n1975_Cortes.
• Ibiricu, Lucio M.; Casal, Gabriel A.; Alvarez, Bruno N.; De Sosa Tomas, Andrea; Lamanna, Matthew C.; Cruzado-Caballero, Penelope (October 2021). "New hadrosaurid (Dinosauria: Ornithopoda) fossils from the uppermost Cretaceous of central Patagonia and the influence of paleoenvironment on South American hadrosaur distribution". Journal of South American Earth Sciences. 110 103369. Bibcode:2021JSAES.11003369I. doi:10.1016/j.jsames.2021.103369.
• Mannion, P.D.; Otero, A. (2012), "A reappraisal of the Late Cretaceous Argentinean sauropod dinosaur Argyrosaurus superbus, with a description of a new titanosaur genus", Journal of Vertebrate Paleontology, 32 (3): 614–638, Bibcode:2012JVPal..32..614M, doi:10.1080/02724634.2012.660898, hdl:11336/197194
• Martínez, R.D.F.; Lamanna, M.C.; Novas, F.E.; Ridgely, R.C.; Casal, G.A.; Martínez, J.E. (2016), "A Basal Lithostrotian Titanosaur (Dinosauria: Sauropoda) with a Complete Skull: Implications for the Evolution and Paleobiology of Titanosauria", PLoS ONE, 11 (4) e0151661, Bibcode:2016PLoSO..1151661M, doi:10.1371/journal.pone.0151661, PMC 4846048, PMID 27115989
• Weishampel, David B.; Dodson, Peter; Osmólska, Halszka (2004), The Dinosauria (2nd ed.), Berkeley: University of California Press, pp. 1–880, ISBN 0-520-24209-2, retrieved 2019-02-21
• Vallati, Patricia; De Sosa Tomas, Andrea; Casal, Gabriel (January 2020). "A Maastrichtian terrestrial palaeoenvironment close to the K/Pg boundary in the Golfo San Jorge basin, Patagonia, Argentina". Journal of South American Earth Sciences. 97 102401. Bibcode:2020JSAES..9702401V. doi:10.1016/j.jsames.2019.102401.