Anacleto Formation

Nests of dinosaur eggs, many with preserved embryos inside, have been discovered in large quantities at the famous Auca Mahuevo locality, and have been attributed to titanosaurs.[6]

Sauropods reported from the Anacleto Formation
Genus	Species	Stratigraphic Position	Presence	Material	Notes	Images
Antarctosaurus	A. wichmannianus		[7]		A titanosaur.
Barrosasaurus	B. casamiquelai	Lower	Neuquén Province.[8]	Vertebrae.[8]	A titanosaur.
Laplatasaurus	L. araukanicus	Uppermost	Several localities in Patagonia.[9]	Multiple specimens.[9]	A titanosaur.
Narambuenatitan	N. palomoi	Lower		Remains of a subadult.[10]	A titanosaur.
Neuquensaurus	N. australis	Uppermost	Cinco Saltos, Río Negro Province.[11]		A saltasaurine.
Pitekunsaurus	P. macayai			"Braincase, left frontal, one tooth, four cervical vertebrae, three dorsal vertebrae, four caudal vertebrae, right ulna and scapula, proximal extreme of left femur, rib fragments and uncertain remains".[12]	A titanosaur.
Teratopodus	T. malarguensis		Southern Mendoza Province.[13]	Footprint trackways.[13]	A titanosaur ichnotaxon.

The oldest known unequivocal bird footprints from South America were discovered in the Anacleto Formation. The small footprints were tentatively assigned to the ichnogenus Aquatilavipes and might have been produced by Patagopteryx (whose fossils were only found in the Bajo de la Carpa Formation however) or some unknown wader-like bird; they lack a hind toe. Ignotornis refers to similar footprints made by larger birds with a small hind toe; they might have been left by Neuquenornis, but this is also only known from the Bajo de la Carpa Formation. Footprints of these two ichnogenera have also been found elsewhere, but it must be understood that assignment to the same ichnogenus does not imply a close relatedness of the organisms that produced these traces, only a similar morphology.[14]

Even smaller and somewhat unusual footprints assigned to Barrosopus are only known from the Anacleto Formation. They were almost certainly made by some tiny theropod, but whether this was a bird is not quite clear: the innermost front toes of the animal leaving these tracks attached in a position higher than the others. In that, and in their dimensions, they are a very close match for the odd-footed enantiornithine bird Yungavolucris brevipedalis, but this is only known from the Maastrichtian Lecho Formation which is some 10 million years younger.[15]

Theropods reported from the Anacleto Formation
Genus	Species	Stratigraphic Position	Presence	Material	Notes	Images
Abelisauridae	Indeterminate	Lower	Northwest Patagonia.[16][17]	MPCN-PV 69, consisting of a partial premaxilla, fragmentary vertebrae, proximal portion of both humeri, distal portion of the pubis, and an incomplete pedal ungual.[16][17]	An indeterminate abelisaurid.
Abelisaurus	A. comahuensis		Lago Pellegrini stone quarries.[18]	Skull.[18]	An abelisaurid, originally thought to be from the Allen Formation.
Aerosteon	A. riocoloradensis		"Cañadon Amarillo (S 37.5°, W 70.5°), north of Cerro Colorado, 1 km north of the Río Colorado near the southern border of Mendoza Province, Argentina."[19]	Skeletal remains.[19]	A megaraptorid.
Aucasaurus	A. garridoi	Upper	Auca Mahuevo.[20]	Skeleton of an adult (MCF-PVPH-236).[20]	An abelisaurid.
Megaraptora indet.	Indeterminate	Upper	Auca Mahuevo.[21]	MCF-PVPH-416, a fragmentary pubic boot with unfused proximal symphysial contact.[21]	A large megaraptoran.

• Chiappe, Luis M. (1993): Enantiornithine (Aves) Tarsometatarsi from the Cretaceous Lecho Formation of Northwestern Argentina. American Museum Novitates 3083: 1-27. [English with Spanish abstract] PDF fulltext
• Coria, Rodolfo A.; Currie, Philip J.; Eberth, David & Garrido, Alberto (2002): Bird footprints from the Anacleto Formation (Late Cretaceous), Neuquén, Argentina. Ameghiniana 39(4): 453-463. [English with Spanish abstract] PDF fulltext
• Fossa Mancini, E.; Feruglio, E.; Yussen de Campana, J.C. (1938). "Una reunión de geólogos de YPF y el problema de la terminología estratigráfica ("A YPF geologists' reunion and the problem of stratigraphy terminology")". Boletín de Informaciones Petroleras. 15: 1–67.
• Leanza, H.A.; Apesteguia, S.; Novas, F.E.; De la Fuente, M.S. (2004). "Cretaceous terrestrial beds from the Neuquén Basin (Argentina) and their tetrapod assemblages". Cretaceous Research. 25: 61–87. doi:10.1016/j.cretres.2003.10.005. Retrieved 2019-02-16 – via ResearchGate.
• Lockley, Martin; Matsukawa, Masaki; Ohira, Hiroto; Li, Jianjun; Wright, Joanna; White, Diane & Chen, Peiji (2006): Bird tracks from Liaoning Province, China: New insights into avian evolution during the Jurassic-Cretaceous transition. Cretaceous Research 27(1): 33-43. doi:10.1016/j.cretres.2005.10.007 (HTML abstract). Erratum: doi:10.1016/j.cretres.2008.06.002
• Salgado, L.; Coria, R.A. & Chiappe, Luis M. (2005): Osteology of the sauropod embryos from the Upper Cretaceous of Patagonia. Acta Palaeontologica Polonica 50(1): 79–92. PDF fulltext
• Sánchez, María Lidia; Heredia, Susana; Calvo, Jorge O. (2006). "Paleoambientes sedimentarios del Cretácico Superior de la Formación Plottier (Grupo Neuquén), Departamento Confluencia, Neuquén (Sedimentary paleoenvironments in the Upper Cretaceous Plottier Formation (Neuquen Group), Confluencia, Neuquén)". Revista de la Asociación Geológica Argentina. 61: 3–18. Retrieved 2019-02-16 – via ResearchGate.