Los Alamitos Formation

Not to be confused with Alamitos Formation.

The Los Alamitos Formation is a geological formation of the North Patagonian Massif in Rio Negro Province, northwestern Patagonia, Argentina, whose strata date back to the Late Cretaceous (Late Campanian to Maastrichtian). Dinosaur remains are among the fossils that have been recovered from the formation.^[1]

Los Alamitos Formation
Stratigraphic range: Late Campanian-Maastrichtian ~85–66 Ma PreꞒ Ꞓ O S D C P T J K Pg N
Type	Geological formation
Sub-units	Coli Toro Member
Lithology
Primary	Siltstone
Other	Sandstone
Location
Coordinates	42.1°S 66.3°W / -42.1; -66.3
Approximate paleocoordinates	45.0°S 52.3°W / -45.0; -52.3
Region	Río Negro Province
Country	Argentina
Extent	North Patagonian Massif
Los Alamitos Formation (Argentina)

Fossil content

Paleogeography of the Late Cretaceous with Los Alamitos Formation indicated

Dinosaurs

Genus	Species	Material	Notes	Images
Aeolosaurus	A. rionegrinus		A titanosaur.
Alamitornis	A. minutus		An ornithuromorph.
Huallasaurus	H. australis	"Partial skulls with associated postcrania, approximately [five] individuals."	A hadrosaur formally named "Kritosaurus" australis. [2][3][4]
cf. Hesperornithes
Indeterminate theropod
Indeterminate ornithurine
Indeterminate avian

Rhynchocephalians

Genus	Species	Material	Notes	Images
Alamitosphenos	A. mineri		[5]
Kawasphenodon	K. expectatus		[6]

Snakes

Genus	Species	Material	Notes	Imaes
Alamitophis	A. elongatus

Mammaliaforms

Genus	Species	Material	Notes	Images
Alamitherium	A. bishopi		[7]
Austrotriconodon	A. sepulvedai
	A. mckennai
Leonardus	L. cuspidatus
Bondesius	B. ferox
Brandonia	B. intermedia
Casamiquelia	C. rionegrina
Ferugliotherium	F. windhauseni
Gondwanatherium	G. patagonicum
Groebertherium	G. novasi
Mesungulatum	M. houssayi		[8]
Paraungulatum	P. rectangularis
Reigitherium	R. bunodontum		[9]
Rougiertherium	R. tricuspes

See also

• List of dinosaur-bearing rock formations

References

1. Weishampel et al., 2004, "Dinosaur distribution (Late Cretaceous, South America).", pp.600-604
2. Rozadilla, Sebastián; Brissón-Egli, Federico; Lisandro Agnolín, Federico; Aranciaga-Rolando, Alexis Mauro; Novas, Fernando Emilio (2022). "A new hadrosaurid (Dinosauria: Ornithischia) from the Late Cretaceous of northern Patagonia and the radiation of South American hadrosaurids". Journal of Systematic Palaeontology. 19 (17): 1207–1235. doi:10.1080/14772019.2021.2020917. S2CID 247122005.
3. Prieto–Marquez, Alberto; Salinas, Guillermo C. (2010). "A re–evaluation of Secernosaurus koerneri and Kritosaurus australis (Dinosauria, Hadrosauridae) from the Late Cretaceous of Argentina". Journal of Vertebrate Paleontology. 30 (3): 813–837. Bibcode:2010JVPal..30..813P. doi:10.1080/02724631003763508. S2CID 85814033.
4. "Table 20.1," in Weishampel, et al.
5. Agnolín, F. L.; Aranciaga Rolando, A. M.; Chimento, N. R.; Novas, F. E. (2023). "New small reptile remains from the Late Cretaceous of Patagonia increase morphological diversity of sphenodontids (Lepidosauria)". Proceedings of the Geologists' Association. 135: 36–44. doi:10.1016/j.pgeola.2023.09.007.
6. Apesteguía, Sebastián (2005-12-01). "A Late Campanian sphenodontid (Reptilia, Diapsida) from northern Patagonia". Comptes Rendus Palevol. 4 (8): 663–669. Bibcode:2005CRPal...4..663A. doi:10.1016/j.crpv.2005.06.003. ISSN 1631-0683.
7. Bonaparte, 1999
8. Bonaparte & Soria, 1985
9. Bonaparte, 1990

Bibliography

• 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