Hornitos Formation

Hornitos Formation
Hornitos Formation
Stratigraphic range: Late Cretaceous, Campanian–Maastrichtian PreꞒ Ꞓ O S D C P T J K Pg N
Type	Geological formation
Lithology
Primary	Limestone, sandstone, conglomerate
Other	Marl, tuff
Location
Coordinates	28°00′S 70°18′W / 28.0°S 70.3°W
Approximate paleocoordinates	30°36′S 54°30′W / 30.6°S 54.5°W
Region	Atacama
Country	Chile
Extent	Algarrobal Basin
	Hornitos Formation (Chile)

The Hornitos Formation is a Campanian geologic formation of the Algarrobal Basin in the Atacama Region of northern Chile. The formation comprises limestones, sandstones, conglomerates, marls and tuff. Dinosaur remains are among the fossils that have been recovered from the formation, including the sauropod Arackar licanantay.^[1]

Description

The Hornillos Formation, deposited in the Algarrobal Basin,^[2] comprises sandstones, limestones, conglomerates, and caliches, intercalated with lavas and andesitic breccias and various volcanic rocks. Between these last is a conspicuous layer of rhyo-dactitic lithic tuff, which reaches up to 10 metres (33 ft) in thickness. Bones of indeterminate titanosaurs appear in a marly limestone stratum of 10 metres (33 ft) thick with decimeter-sized calcareous concretions. The smallest pieces were found as rollings, whereas the larger piece was included in the limestone.^[3]

The Hornitos Formation formerly was thought to be of Paleocene to Eocene age.^[4] The formation may be older and belong to the Early Cretaceous, as a granite intruded the rocks about 105 ± 10 Ma.^[5]

Fossil content

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.

Dinosaurs

Sauropods

Sauropods of the Hornitos Formation
Genus	Species	Location	Stratigraphic position	Material	Notes	Images
Arackar^[6]	A. licanantay	Atacama Region	Campanian to Maatrishtian	Femur, Humerus and Ischium	A lithostrotian titanosaur; closely related to Isisaurus colberti.

References

^ Weishampel, et al. (2004). "Dinosaur distribution." pp. 517–607.
^ Abad, 1982, p. 5
^ Hornitos at Fossilworks.org
^ Rivera Cabello, 1985, p. 5
^ Rivano et al., 1986, p. 28
^ Rubilar-Rogers D, Vargas AO, Riga BG, Soto-Acuña S, Alarcón-Muñoz J, Iriarte-Díaz J, Arévalo C, Gutstein CS (2021). "Arackar licanantay gen. et sp. nov. a new lithostrotian (Dinosauria, Sauropoda) from the Upper Cretaceous of the Atacama Region, northern Chile". Cretaceous Research. 124: Article 104802. Bibcode:2021CrRes.12404802R. doi:10.1016/j.cretres.2021.104802. S2CID 233780252.

Bibliography

Abad E., Eduardo (1982), Un modelo de depositación de uranio en la Cuenca de Algarrobal, Vallenar, Chile (PDF), III Congreso Geológico Chileno, pp. 1–37, archived from the original (PDF) on 2018-09-09, retrieved 2018-09-08
Rivano G., Sergio (1986), "Antecedentes radiométricos para una edad cretácica inferior de la Formación Las Chilcas", Andean Geology, 27: 27–32, retrieved 2018-09-08
Rivera Cabello, Sergio (1985), Una discusión sobre la edad de las formaciones Cerrilos y Hornitos, Región de Atacama (PDF), IV Congreso Geológico Chileno, pp. 1–13, archived from the original (PDF) on 2018-09-09, 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