Plottier Formation

Plottier Formation
Stratigraphic range: late Coniacian-early Santonian ~86–85 Ma PreꞒ Ꞓ O S D C P T J K Pg N ↓
Type	Geological formation
Unit of	Neuquén Group  Río Neuquén Subgroup
Underlies	Río Colorado Subgroup  Bajo de la Carpa Formation
Overlies	Sierra Barrosa Formation
Thickness	Up to 25 m (82 ft)
Lithology
Primary	Claystone
Other	Sandstone
Location
Coordinates	37°24′S 69°06′W / 37.4°S 69.1°W / -37.4; -69.1
Approximate paleocoordinates	42°12′S 49°24′W / 42.2°S 49.4°W / -42.2; -49.4
Region	Mendoza, Neuquén & Río Negro Provinces
Country	Argentina
Extent	Neuquén Basin
Type section
Named for	Plottier
Named by	Fossa Mancini et al.
Year defined	1938
Plottier Formation (Argentina)

The Plottier Formation is a geologic formation that outcrops in the Argentine Patagonian provinces of Río Negro and Neuquén. It is the younger of two formations belonging to the Río Neuquén Subgroup within the Neuquén Group of the Neuquén Basin, with the oldest rocks dating from the late Coniacian and its youngest maybe from the very start of the Santonian. Formerly, that subgroup was treated as a formation, and the Plottier Formation was known as the Plottier Member.^[1]

A section near the Neuquén City airport, north of the town of Plottier, is the type locality of the Plottier Formation.^[2] At its base, this formation grades into the Portezuelo Formation, and it is in turn overlain conformably by the Bajo de la Carpa Formation, a unit of the Río Colorado Subgroup.

The Plottier Formation is the thinnest formation within the Neuquén Group, with a maximum thickness of only 25 metres (82 ft). It is differentiated from the underlying Portezuelo Formation primarily by its higher content of argillites (mud deposits) and was deposited under fluvial conditions. In 2006, a detailed lithostratigraphic and paleoecological study of a section of the Plottier Formation was published. This section contained alluvial deposits laid down by what was essentially a low-gradient wandering river throughout the millions of years, but often was of a single-channel type with little meandering.^[3][1]

Few animal fossils are known from this formation, including:^[4]

A footprint track of an ornithopod is known from the Middle Loma de la Lata site.^[10]

Ornithischians reported from the Plottier Formation
Genus	Species	Presence	Material	Notes	Images
Ornithopoda indet.[5][11]	Indeterminate	El Anfiteatro	A pedal ungual phalanx (MPCA-AT 261)	An ornithopod roughly the size of Notohypsilophodon
	Indeterminate	Puesto Hernández quarry	Partial dorsal neural arch (MAU-Pv-PH-458)	An ornithopod similar to Macrogryphosaurus, estimated to be 6 meters long

12 footprint tracks of a sauropod are known from the site of Proyecto Dino.^[10]

Sauropods reported from the Plottier Formation
Genus	Species	Presence	Material	Notes	Images
Aeolosaurini indet.[12]	Indeterminate	Yacimiento Narambuena	Four articulated caudal vertebrae (MAU-Pv-N-414)	A titanosaur
Antarctosaurus[13]	A. giganteus	Aguada del Caño	Partial skeleton (MLP 26-316)	A titanosaur
Muyelensaurus[14][15]	M. pecheni	Loma del Lindero	Partial skeleton & additional vertebrae	A titanosaur, specimens originally thought to be from the Portezuelo Formation
Notocolossus[16][17]	N. gonzalezparejasi	Cerro Guillermo	Two partial skeletons (UNCUYO-LD 301 & UNCUYO-LD 302)	A titanosaur
Petrobrasaurus[18]	P. puestohernandezi	Rincón de los Sauces	Partial skeleton	A titanosaur
Sauropoda indet.[15][17]	Indeterminate	5 kilometers north of Plottier	Partial right tibia (MCF-PVPH-899)	A sauropod
	Indeterminate	Cerro Guillermo	Incomplete skeleton (IANIGLA-PV.113)	A sauropod
Titanosauria indet.[5][15]	Indeterminate	El Anfiteatro	Incomplete dorsal vertebra (MPCA-AT 024)	A large titanosaur
	Indeterminate	5 kilometers north of Plottier	Left femur and partial ribs (MCF-PVPH-889) Right fibula (MCF-PVPH-900)	Remains of titanosaurs

Pterosaurs reported from the Plottier Formation
Genus	Species	Presence	Material	Notes	Images
Thanatosdrakon[23]	T. amaru	Agua del Padrillo	Partial skeleton (UNCUYO-LD 307) Left humerus (UNCUYO-LD 350)	An azhdarchid

Turtles reported from the Plottier Formation
Genus	Species	Presence	Material	Notes	Images
Chelidae? indet.[5]	Indeterminate	El Anfiteatro	Plastron plate (MPCA-AT 089)	A chelid
Linderochelys[24]	L. rinconensis	Loma de Lindero	Partial skeleton (MAU-PV-LL-69)	A chelid, locality originally assigned to the Rio Neuquén Subgroup with no specific formation.
Rionegrochelys[5][25]	R. caldieroi	El Anfiteatro	Shell elements	A chelid, type specimen first reported as an indeterminate chelid in 2009

• Ichnofossils
  • Scoyenia sp.
  • Taenidium sp.

There are also ichnofossils left on the river's mudflats, as well as fossil freshwater bivalves.^[1]

• List of fossil sites
• List of dinosaur bearing rock formations

• 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 (in Spanish). 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. Bibcode:2004CrRes..25...61L. doi:10.1016/j.cretres.2003.10.005. Retrieved 2019-02-16.
• 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 (in Spanish). 61: 3–18. Retrieved 2019-02-16.