Huincul Formation

Not to be confused with Huincul Fault.

The Huincul Formation is a geologic formation of Late Cretaceous (Cenomanian to Early Turonian) age of the Neuquén Basin that outcrops in the Mendoza, Río Negro and Neuquén Provinces of northern Patagonia, Argentina.^[1] It is the second formation in the Río Limay Subgroup, the oldest subgroup within the Neuquén Group. Formerly, that subgroup was treated as a formation, and the Huincul Formation was known as the Huincul Member.^[2]

Huincul Formation
Stratigraphic range: Late Cenomanian-Early Turonian ~97–93 Ma PreꞒ Ꞓ O S D C P T J K Pg N ↓
Type	Geological formation
Unit of	Neuquén Group  Río Limay Subgroup
Underlies	Lisandro Formation
Overlies	Candeleros Formation
Thickness	250 m (820 ft)
Lithology
Primary	Sandstone
Other	Claystone
Location
Coordinates	39.4°S 69.0°W / -39.4; -69.0
Approximate paleocoordinates	46.1°S 46.0°W / -46.1; -46.0
Region	Mendoza, Río Negro & Neuquén Provinces
Country	Argentina
Extent	Neuquén Basin
Type section
Named for	Plaza Huincul
Named by	Keidel
Year defined	1929
Huincul Formation (Argentina)

Description

The type locality of the Huincul Formation is near the town of Plaza Huincul in Neuquén Province after which the formation was named by Wichmann in 1929.^[3] This formation conformably overlies the Candeleros Formation, and it is in turn overlain by the Lisandro Formation.

The Huincul Formation is thought to represent an arid environment with ephemeral or seasonal streams.^[4] In some areas, it is up to 250 metres (820 ft) thick. It is mainly composed of green and yellow sandstones and can easily be differentiated from the overlying Lisandro Formation, which is red in color. The Candeleros Formation, underlying the Huincul, is composed of darker sediments, making all three formations easily distinguishable.^[2][5]

Paleobiota

Fauna of Huincul Formation

Dinosaur fossils are frequently found in the Huincul Formation. The titanosaurian sauropod Argentinosaurus huinculensis, one of the largest known land animals, is named after the formation.^[2] Another noteworthy Huincul dinosaur is the carcharodontosaurid theropod Mapusaurus roseae, which is regarded as one of the largest known terrestrial predators.^[4]

Dinosaurs

Apart from sauropods and theropods, rare fossils of iguanodonts and other ornithopods have been recorded in the formation.^[6] Ichnofossils (footprints) of abelisaurid theropods and hadrosaurs are also known.^[7]

Ornithischians

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.

Ornithischians of the Huincul Formation
Taxa	Species	Locality	Stratigraphic unit	Material	Notes	Images
Chakisaurus[8]	C. nekul	Pueblo Blanco Natural Reserve	Lower[9][10]	Multiple partial skeletons belonging to individuals of different ages	An elasmarian ornithopod; the first ornithischian named from the Huincul Formation

Sauropods

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.

Sauropods of the Huincul Formation
Genus	Species	Locality	Stratigraphic unit	Material	Notes	Images
Argentinosaurus	A. huinculensis	Las Overas	Upper	Seven dorsal vertebrae, partial sacrum, partial dorsal rib, fibula, and potentially other hindlimb bones	One of the largest titanosaurs known from relatively complete remains
Astigmasaura[11]	A. genuflexa	El Orejano	Lower	A partial articulated skeleton including tail vertebrae, the pelvic girdle, and both hindlimbs	A rebbachisaurid
Bustingorrytitan	B. shiva	Villa El Chocón	Lower	Four specimens are known, including dentary and postcranial skeleton parts.	A titanosaur
Cathartesaura	C. anaerobica[12]	La Buitrera	Lower	A partial skeleton consisting of vertebrae and limb bones.	A rebbachisaurid
Choconsaurus	C. baileywillisi[13]	Villa El Chocón	Lower	Partial skeleton without a skull, MMCh-PV 44/10.	A titanosaur
Chucarosaurus	C. diripienda	Violante farm.	Lower[9][10]	A complete left humerus, partial left radius, complete left metacarpal II, left ischium, partial left femur and fibula, partial right tibia, and partial indeterminate metapodial.[14]	A titanosaur
Cienciargentina	C. sanchezi[15]	Villa El Chocon	Lower	Multiple partial skeletons including several vertebrae and limb bones	A rebbachisaurid
Limaysaurus	L. tessonei	Villa El Chocón	Lower	A partial articulated skeleton composed by two sacrals, the first six caudals, pubis and ischium.	A rebbachisaurid	Limaysaurus
Sidersaura	S. marae	Barda Atravesada de Las Campanas	Lower	Multiple partial skeletons including partial pelvic and pectoral girdles, limb bones, and vertebrae	A rebbachisaurid

Theropods

Theropods of the Huincul Formation
Taxa	Species	Locality	Stratigraphic unit	Material	Notes	Images
Aoniraptor	A. liberataem	Violante Farm	Lower[9][10]	Sacral vertebra, six proximal caudal vertebrae, four mid-caudal vertebrae.[16]	Possibly a megaraptoran
Gualicho	G. shinyae	Violante Farm	Lower[9][10]	A partial skeleton lacking the skull along with several veterbraes, ribs, the left shoulder girdle, the left forelimb, the right lower arm, the lower ends of both pubic bones, thighbones, shinbones, calf bones, metatarsi and three toes of the right foot (Holotype MPCN PV 0001).	A theropod of uncertain affinities
Huinculsaurus	H. montesi	Aguada Grande	Upper	Several vertebrae[17]	A noasaurid
Ilokelesia	I. aguadagrandensis	Aguada Grande	Upper	Fragmented skull and the axial, appendicular skeleton.	An abelisaurid	Ilokelesia
Mapusaurus[18]	M. roseae	Cañadón del Gato	Upper (middle section of formation)[19]	Multiple skeletal specimens.	A carcharodontosaurid
Meraxes	M. gigas[19]	Las Campanas Creek	Lower	A nearly complete skull, pectoral and pelvic elements, partial forelimbs, complete hindlimbs, fragmentary ribs, and cervical and dorsal vertebrae, a sacrum, and several complete caudal vertebrae.	A carcharodontosaurid	Meraxes gigas reconstruction
Overoraptor	O. chimentoi[20]	Violante Farm	Lower[9][10]	Skeletal specimen consists of two phalanges and a metacarpal of the right hand, two hemal arches, the right scapula, the right ulna, a partial ilium, a partial pubis, two metatarsals from each foot, and several phalanges and unguals from the left foot.	A paravian
Skorpiovenator	S. bustingorryi	Bustingorry's Farm	Lower	A partial skeleton	An abelisaurid
Taurovenator[16]	T. violantei[16]	Violante Farm	Lower[9][10]	An isolated right postorbital and a referred partial skeleton.	A carcharodontosaurid
Tralkasaurus	T. cuyi	Violante Farm	Lower [9][10]	An incomplete skeleton ( MPCA-Pv 815), which comprises a maxilla; dorsal, sacral, and caudal vertebrae; cervical ribs; and a badly-preserved pubis.	An abelisaurid

Other reptiles

Apart from the taxa named here, fossils of unnamed squamates and neosuchian crocodyliforms have been discovered in the formation.^[21]

Non-dinosaur reptiles of the Huincul Formation
Genus	Species	Locality	Stratigraphic unit	Material	Notes	Images
Kaikaifilusaurus	K. sp.	Violante's Farm	Lower	Incomplete right dentary[9]	An eilenodontine rhynchocephalian
Patagosphenos[9]	P. watuku	Violante's Farm	Lower	Disarticulated skull with shoulder and limb fragments	An eilenodontine rhynchocephalian
Prochelidella [22]	P. buitreraensis	La Buitrera	Upper	A partial skeleton with a skull, two cervical vertebrae, a partial left humerus, a partial left ulna, a partial left radius, a right pelvic girdle, a nuchal, and a right first costal.	A chelid turtle

See also

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