Coli Toro Formation

Coli Toro Formation
Stratigraphic range: Maastrichtian-Danian
Type	Formation
Overlies	Angostura Colorada Formation
Lithology
Primary	Sandstone
Location
Coordinates	41°00′S 69°30′W / 41.0°S 69.5°W / -41.0; -69.5
Approximate paleocoordinates	43°36′S 55°24′W / 43.6°S 55.4°W / -43.6; -55.4
Region	Río Negro Province
Country	Argentina
Extent	Neuquén Basin
Coli Toro Formation (Argentina)

The Coli Toro Formation is a Maastrichtian-Danian geological formation in Argentina. Dinosaur remains are among the fossils that have been recovered from the formation, although none have yet been referred to a specific genus.^[1] The rocks of the formation were deposited in a marine environment, in opposition to the marginal underliying sedimentary environment.

The formation in later publications has been reassigned as the Coli Toro Member at the basal levels of the Los Alamitos Formation, containing fossil remains of Sulcusuchus erraini.^[2] The formation partly overlies the Angostura Colorada Formation.^[3]

Fossil content

Dinosaurs from the Coli Toro Formation

Genus	Species	Location	Stratigraphic Position	Material	Notes	Images
Hadrosauridae[4]	Indeterminate	Cerro Yeso		Isolated caudal vertebrae	Indeterminated hadrosaurids, probably related to other south american Austrokritosaurians
Titanosauria[4]	Indeterminate	Cerro Yeso		A tooth (MHJG-NCP, formerly 5/4/7-3)	Indeterminated Titanosaurian sauropod
Abelisauridae[4]	Indeterminate	Estancia Yuquinche		A tooth (MHJG-NCP 299)	The first theropod from the Coli Toro Formation
Parankylosauria[5]	Indeterminate	Bajo Colorado		Osteoderm associated to a cranial fragment (MJHG 77-33) and a rib piece (MJHG 271B-17)	The osteorderm is similar to the jugal-quadratojugal osteoderm of the La Colonia Parankylosaur, and the rib is T-shaped in cross view, as in other parankylosaurs and euankylosaurs May also be from the Angostura Colorada Formation

Other reptiles from the Coli Toro Formation

Genus	Species	Location	Stratigraphic Position	Material	Notes	Images
Peirosauridae ?[4]	Indeterminate	Cerro Yeso		A tooth (MHJG Pa 614 106)	A indeterminated crocodyliform tooth, probably belonging to the Notosuchian family Peirosauridae
Sulcusuchus[4][6]	S. erraini	Cerro Yeso and near Laguna Cari-Laufquén Grande		Teeth (Cerro Yeso) and a fragmentary mandibular ramus (Laguna Cari-Laufquén Grande)	The only named Polycotylid from the Southern Hemisphere, and the most recent one worldwide. Also found in La Colonia Formation[7]
Testudines[4]	Indeterminate	Cerro Yeso		Turtle plates are reportly commonly found in the Cerro Yeso locality	Perhaps related to the other Pleurodirans from neighbouring Maastrichtian formations

FIsh from the Coli Toro Formation

Genus	Species	Location	Stratigraphic Position	Material	Notes	Images
Metaceratodus?[4]	Indeterminate	Cerro Yeso		Dental plates	A lungfish, if confirmed, also found in the La Colonia Formation
Osteichthyes[4]	Indeterminate	Cerro Yeso		Vertebrae and ganoid scales

See also

• Earth sciences portal
• Paleontology portal
• Dinosaurs portal

• Angostura Colorada Formation
• La Colonia Formation
• Los Alamitos Formation
• Allen Formation
• Jaguel Formation
• Chorrillo Formation
• Calafate Formation
• El Molino Formation
• Yacoraite Formation
• Vilquechico Formation
• Serra da Galga Formation
• List of dinosaur-bearing rock formations
  • List of stratigraphic units with indeterminate dinosaur fossils

References

1. Weishampel, et al. (2004). "Dinosaur distribution." Pp. 517-607.
2. Cari-Laufqen Grande Pond at Fossilworks.org
3. Ottone, 2009, p.377
4. Paulina-Carabajal, Ariana; Méndez, Ariel; Ulloa-Guaiquin, Karen; González-Dionis, Javier; Irazoqui, Facundo (2025). "The First Record of Theropod Dinosaur Remains From the Angostura Colorada and Coli Toro Formations (Campanian-Maatrichtian) in the Ingeniero Jacobacci Area (Rio Negro Province, Argentina)". Ameghiniana. doi:10.5710/AMGH.17.09.2025.3643.
5. Becerra, Marcos G.; Juárez Valieri, R.D; Meso, J.G; Guzmán, F.A; Heredia, J. (2024). "New remains of ankylosaurs in Río Negro (Argentina) found while revisiting collections in museums expand their presence to new late Cretaceous localities". Conicet. Retrieved October 7, 2025.
6. O’gorman, José P.; Gasparini, Zulma (2013-06-01). "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. ISSN 0311-5518.
7. O’Gorman, José P.; Aspromonte, Franco R.; Matelo Mirco, Gonzalo (2025). "First record of lithophagy in Sulcusuchus erraini (Plesiosauria; Polycotylidae) with comments on the taphonomic and collect bias in gastroliths". Historical Biology. 0: 1–13. doi:10.1080/08912963.2025.2548329. ISSN 0891-2963.

Bibliography

• Ottone, Eduardo G (2009), "La flora cretácica de Cuenca Neuquina, su significado paleoambiental y paleoclimático" (PDF), Revista de la Asociación Geológica Argentina, 65: 373–386, retrieved 2018-09-08
• Weishampel, David B.; Dodson, Peter; Osmólska, Halszka (2004), The Dinosauria, 2nd edition, Berkeley: University of California Press, pp. 1–880, ISBN 0-520-24209-2, retrieved 2019-02-21

Further reading

• R. M. Casamiquela. 1964. Sobre un dinosaurio hadrosáurido de la Argentina. Ameghiniana 3(9):285-312
• 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