El Gallo Formation

The El Gallo Formation is a geological formation in Mexico whose strata date back to the Late Cretaceous, Campanian epoch, specifically dated to 75.21 ± 0.07 Ma and 74.55 ± 0.09 Ma.[1] Dinosaur remains are among the fossils that have been recovered from the formation.[2]

El Gallo Formation Stratigraphic range: Campanian 75.28–74.46 Ma PreꞒ Ꞓ O S D C P T J K Pg N ↓
Type	Geological formation
Sub-units	El Disecado Member
Thickness	up to ca. 1,150 m (3,770 ft) (El Disecado Member)
Lithology
Primary	Mudstone, sandstone
Other	Siltstone
Location
Coordinates	30.1°N 115.8°W
Approximate paleocoordinates	35.5°N 85.8°W
Region	Baja California
Country	Mexico
El Gallo Formation (Mexico)

Paleogeography of the Campanian

Vertebrate paleofauna

Crurotarsans

Crurotarsans of the El Gallo Formation
Genus	Species	Location	Member	Abundance	Notes	Images
Brachychampsa	[3]
Leidyosuchus

Dinosaurs

Indeterminate theropod, coelurosaur, dromaeosaurid, tyrannosaurid, hadrosaurid, and ankylosaurid remains are known from the formation.[4] Dinosaur eggs are known from the formation.[5] Alexornis antecedens actually comes from the La Bocana Roja Formation. An indeterminate hadrosaurine is known from the formation.[6]

Dinosaurs of the El Gallo Formation
Genus	Species	Location	Member	Abundance	Notes	Images
cf. Chirostenotes[4]	C. sp.
Gryposaurus[6]	Indeterminate
Lambeosaurus[7]	L. laticaudus[7]
Magnapaulia	M. laticaudus
Saurornitholestinae[4]	Indeterminate
cf. Troodon[8]	T. formosus[8]
Tyrannosauridae[4]	Indeterminate				Possibly represents a new taxon.[4]

Lepidosaurs

Lepidosaurs of the El Gallo Formation
Genus	Species	Location	Member	Abundance	Notes	Images
Paraglyphanodon[9]	Indeterminate[9]				Probably a juvenile Polyglyphanodon.[5]
Polyglyphanodon[5]	P. bajaensis[5]

Mammals

Mammals of the El Gallo Formation
Genus	Species	Location	Stratigraphic position	Abundance	Notes	Images
Mesodma[10]	M. formosa[10]
Pediomys[5]	Indeterminate[5]
Stygimys[9]	Indeterminate[9]

Amphibians

An indeterminate albanerpetontid is known from the formation.[11]

See also

• List of dinosaur-bearing rock formations
• List of fossiliferous stratigraphic units in Mexico

References

1. El Gallo Formation at Fossilworks.org
2. "El Gallo Formation." Weishampel et al., 2004, pp.587-588
3. "Appendix: Summary of the Mesozoic Reptilian Fossils of California," in Hilton (2003) p. 277
4. Ramírez-Velasco, A. A.; Hernández-Rivera, R. (2015). "Diversity of late cretaceous dinosaurs from Mexico" (PDF). Boletín Geológico y Minero. 126 (1): 63–108.
5. "El Gallo Formation, Baja California Del Norte, Mexico," in Sullivan and Lucas (2006). Page 16.
6. Cabrera Hernandez, Jonathan S.; Hernandez Rivera, René; Montellano, Marisol (2018). "FOSSIL EGGSHELLS AND TWO PERINATAL DINOSAURS FROM THE EL GALLO FORMATION (LATE CRETACEOUS), EL ROSARIO, BAJA CALIFORNIA, MEXICO". Journal of Vertebrate Paleontology, Program and Abstracts. 38.
7. "Appendix: Summary of the Mesozoic Reptilian Fossils of California," in Hilton (2003) p. 260
8. "4.5 Estado de Baja California Norte, Mexico; 1. El Gallo Formation," in Weishampel, et al. (2004). Pages 587-588.
9. Listed as "cf. Paraglyphanodon" in "El Gallo Formation, Baja California Del Norte, Mexico," in Sullivan and Lucas (2006). Page 16.
10. Listed as "Mesodma cf. M. formosa" in "El Gallo Formation, Baja California Del Norte, Mexico," in Sullivan and Lucas (2006). Page 16.
11. Romo de Vivar Martínez, Paulo R.; Montellano Ballesteros, Marisol; García Alcántara, Dalia; Romo de Vivar Martínez, Paulo R.; Montellano Ballesteros, Marisol; García Alcántara, Dalia (December 2016). "Primer registro de la Familia Albanerpetontidae (Lissamphibia) en la formación El Gallo (Campaniano, Cretácico Superior), Baja California, México". Boletín de la Sociedad Geológica Mexicana (in Spanish). 68 (3): 571–580. ISSN 1405-3322.

Bibliography

• Sullivan, R.M., and Lucas, S.G. 2006. "The Kirtlandian land-vertebrate "age" – faunal composition, temporal position and biostratigraphic correlation in the nonmarine Upper Cretaceous of western North America." New Mexico Museum of Natural History and Science, Bulletin 35:7-29
• Weishampel, David B.; Peter Dodson, and Halszka Osmólska (eds.). 2004. The Dinosauria, 2nd edition, 1–880. Berkeley: University of California Press. Accessed 2019-02-21. ISBN 0-520-24209-2
• Hilton, Richard P. 2003. Dinosaurs and Other Mesozoic Reptiles of California. Berkeley: University of California Press. 318 pp.

Further reading

• M. L. Chavarria-Arellano, T. R. Simões, and M. Montellano-Ballesteros. 2018. New data on the Late Cretaceous lizard Dicothodon bajaensis (Squamata, Borioteiioidea) from Baja California, Mexico reveals an unusual tooth replacement pattern in squamates. Anais da Academia Brasileira de Ciências
• O. A. López Conde, J. Sterli, M. L. Chavarría Arellano, D. B. Brinkman, and M. Montellano Ballesteros. 2018. Turtles from the Late Cretaceous (Campanian) of El Gallo Formation, Baja California, Mexico. South American Journal of Earth Sciences 88:693-699
• B. R. Peecook, J. A. Wilson, R. Hernandez-Rivera, M. Montellano-Ballesteros, and G. P. Wilson. 2014. First tyrannosaurid remains from the Upper Cretaceous "El Gallo" Formation of Baja California, Mexico. Acta Palaeontologica Polonica 59(1):71-80
• A. A. Ramírez Velasco, R. Hernández Rivera, and R. Servin Pichardo. 2014. The hadrosaurian record from Mexico. In D. A. Eberth & D. C. Evans (ed.), Hadrosaurs 340-360
• H. E. Rivera Sylva, K. Carpenter, and F. J. Aranda Manteca. 2011. Late Cretaceous nodosaurids (Ankylosauria: Ornithischia) from Mexico. Revista Mexicana de Ciencias Geológicas 28(3):371-378
• W. J. Morris. 1973. Mesozoic and Tertiary vertebrates in Baja California. National Geographic Society Research Reports (1966) 7:197-209
• A. Silva Bárcenas. 1969. Localidades de vertebrados fósiles en la Republica Méxicana [Vertebrate fossil localities in the Mexican Republic]. Universidad Nacional Autónoma de México, Instituto de Geología, Paleontología Mexicana 28:1-34
• W. Langston and M. H. Oakes. 1954. Hadrosaurs in Baja California. Bulletin of the Geological Society of America 65(12):1344