Anacleto Formation
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The Anacleto Formation is a geologic formation with outcroppings in the Argentine Patagonian provinces of Mendoza, Río Negro, and Neuquén. It is the youngest formation within the Neuquén Group and belongs to the Río Colorado Subgroup.
The type locality of this formation lies 40 kilometers west of the city of Neuquén. At its base, the Anacleto Formation conformably overlies the Bajo de la Carpa Formation, also of the Río Colorado Subgroup, and it is in turn unconformably overlain by the Allen Formation of the younger Malargüe Group[1][2]
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[edit] Age
Era: Mesozoic
Period: Late Cretaceous
Faunal stage: early Campanian
Absolute Age: ~83 to ~78 mya
[edit] Composition
The Anacleto Formation varies between 60 and 90 meters thick, and consists mainly of claystones and mudstones, purple and dark red in color, of fluvial origin. Geodes are often found scattered throughout this formation.
[edit] Paleontology
Numerous fossils, especially dinosaurs, have been described from the Anacleto Formation, including:
- lizards
- abelisaurid theropods (including Abelisaurus and Aucasaurus)
- other theropods
- several titanosaurian sauropods (including Antarctosaurus and Pellegrinisaurus)
- an ornithopod (Gasparinisaura)
- mammals
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.[3] The oldest known South American bird footprints were also discovered in the Anacleto Formation.
[edit] See also
- List of fossil sites (with link directory)
[edit] References
- ^ Fossa Mancini, E., Feruglio, E., Yussen de Campana, J.C.. 1938. Una reunión de geólogos de YPF y el problema de la terminología estratigráfica. 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(1): 61-87.
- ^ Salgado, L., Coria, R.A., and Chiappe, L.M. 2005. Osteology of the sauropod embryos from the Upper Cretaceous of Patagonia. Acta Palaeontologica Polonica 50(1): 79–92.
