Allen Formation

Last updated
Allen Formation
Stratigraphic range: Mid Campanian-Maastrichtian
~73–69  Ma
O
S
D
C
P
T
J
K
Pg
N
Fms Anacleto Allen Auca Mahuida 1.jpg
Outcrop of the Allen and Anacleto Formations at Auca Mahuida
Type Geological formation
Unit of Malargüe Group
Underlies Jagüel Formation
Overlies Anacleto Formation
Thicknessup to 70 m (230 ft)
Lithology
Primary Mudstone, sandstone
Other Limestone
Location
Coordinates 40°00′S66°36′W / 40.0°S 66.6°W / -40.0; -66.6
Approximate paleocoordinates 42°48′S52°12′W / 42.8°S 52.2°W / -42.8; -52.2
Region Neuquén, Río Negro & La Pampa Provinces
CountryArgentina
Extent Neuquén Basin
Type section
Named byUliana & Dellapé
Year defined1981
Relief Map of Argentina.jpg
Lightgreen pog.svg
Allen Formation (Argentina)

The Allen Formation is a geological formation in Argentina whose strata date back to the Late Cretaceous (middle Campanian to early Maastrichtian. [1] Dinosaur remains are among the fossils that have been recovered from the formation. [2] Indeterminate chelid remains and other vertebrates have also been discovered in this formation. [3]

Contents

Description

Fauna of Allen Allen Formation Fauna.png
Fauna of Allen

The stratotype of the formation was defined by Uliana and Dellapé in 1981 in the eastern area of the Bajo de Añelo, where the relation between base and top is clearly exposed. The deposits are mostly clastic, interbedded with banks of limestone and layers of anhydrite, which were defined continental and shallow marine facies associated with semiarid conditions. [4]

The interpreted sedimentary paleoenvironments range from purely continental such as ephemeral lacustrine, aeolian and fluvial systems to coastal marine paleoenvironments with development of estuaries and tidal flats, followed by a lagoon sedimentary stage from marsh to sea with carbonate precipitation in an area protected from waves, ending with a retraction leading to the accumulation of evaporites. [4]

A detailed facies analysis of the formation was performed by Armas and Sánchez in 2015, where the authors concluded the formation represents a hybrid coastal system of tidal flats, dominated by Atlantic ingressions, with a large storm influence in some areas linked to aeolian systems. [5]

Fossil content

Life restoration of Dinosaurs discovered from Allen Formation Quilmesaurus hunting Bonapartesaurus version 2.jpg
Life restoration of Dinosaurs discovered from Allen Formation

Dinosaurs

Color key
Taxon Reclassified taxonTaxon falsely reported as presentDubious taxon or junior synonym Ichnotaxon Ootaxon Morphotaxon
Notes
Uncertain or tentative taxa are in small text; crossed out taxa are discredited.

Dinosaur eggs are known from the formation. [6]

Ornithischians

Color key
Taxon Reclassified taxonTaxon falsely reported as presentDubious taxon or junior synonym Ichnotaxon Ootaxon Morphotaxon
Notes
Uncertain or tentative taxa are in small text; crossed out taxa are discredited.
Ankylosaurs
Ankylosaurs reported from the Allen Formation
GenusSpeciesLocationStratigraphic positionMaterialNotesImages
Patagopelta P. cristataSalitral Moreno locality.LowerTooth, three posterior dorsal vertebrae, caudal vertebrae, two caudal centra, right femur, partial cervical half ring, and osteoderms.A parankylosaur of uncertain affinities.
Patagopelta into the water.png
Hadrosaurs
Color key
Taxon Reclassified taxonTaxon falsely reported as presentDubious taxon or junior synonym Ichnotaxon Ootaxon Morphotaxon
Notes
Uncertain or tentative taxa are in small text; crossed out taxa are discredited.
Hadrosaurs reported from the Allen Formation
GenusSpeciesLocationStratigraphic positionMaterialNotesImages
Bonapartesaurus B. rionegrensisSalitral Moreno and Islas Malvinas.LowerA partial skeleton.A hadrosaur.
Bonapartesaurus rionegrensis.png
Kelumapusaura K. machiUpperPartial skull, a cervical vertebrae, several sacrals, sternal rib and sternal plate, and multiple referred specimens found in a bonebedA saurolophine hadrosaur.
[9]
Kelumapusaura.jpg
Lapampasaurus L. cholinoiLowerElements of the axial and appendicular skeleton of a subadult individualA hadrosaur.
Willinakaqe W. salitralensisSalitral Moreno site.LowerA right premaxilla.A saurolophine hadrosaur.

Saurischians

Sauropods
Color key
Taxon Reclassified taxonTaxon falsely reported as presentDubious taxon or junior synonym Ichnotaxon Ootaxon Morphotaxon
Notes
Uncertain or tentative taxa are in small text; crossed out taxa are discredited.
Sauropods reported from the Allen Formation
GenusSpeciesLocationStratigraphic positionMaterialNotesImages
Aeolosaurus IndeterminateLowerA titanosaur.
[6]
Aeolosaurus-rionegrinus-JD-2020-1.png

Bonatitan

B.reigi [12]

LowerBraincases, caudal vertebrae, and several limb elementsA titanosaur.
Menucocelsior M. arriagadaiLowerSeventeen caudal vertebrae and several appendicular bones: a right humerus, a left fibula and some metapodial.A titanosaur.
Panamericansaurus P. schroederi"Five tail vertebrata, sacral vertebrae, left humerus and rib fragments"A titanosaur.
Pellegrinisaurus?P. powelliLower (if it is from the formation)"Dorsal and caudal vertebrae, partial femur"A titanosaur.
Pellegrinisaurus Skeleton reconstruction.jpg
Rocasaurus R. munioziLower"Partial postcranial skeleton"A titanosaur.

Theropods

Theropods reported from the Allen Formation
GenusSpeciesLocationStratigraphic positionMaterialNotesImages
Austroraptor A. cabazaiLowerA fragmentary skeleton including parts of the skull, lower jaw, a few neck and torso vertebrae, some ribs, a humerus, and assorted bones from both legsA dromaeosaurid.
Austroraptor Reconstruction.jpg
Bonapartenykus B. ultimusUpperA holotype consists of a mid-dorsal vertebra, both scapulocoracoids, left tibia and femur, left pubis articulated with the pubic peduncle of the ilium, the anterior blade of the left ilium, and two partially preserved eggs.An alvarezsauroid.
Bonapartenykus.png
Lamarqueavis L. australisLower"Right coracoid with damaged sternal and omal extremities, and lacking acrocoracoidal process"An ornithuran.
Limenavis L. patagonicaLower"Partial forelimb"An ornithuran.
Niebla N. antiquaUpperBraincase, fragmentary jaw and teeth, relatively complete scapulocoracoid, dorsal ribs, and incomplete vertebrae.An abelisaurid [18]
Abelisauridae-Niebla-antiqua.jpg
Quilmesaurus Q. currieiUpperFemur and distal tibiaAn abelisaurid.
Quilmesaurus curriei.jpg

Pterosaurs

Fragmentary fossils are known from the formation. [6]

Pterosaurs reported from the Allen Formation
GenusSpeciesLocationStratigraphic positionMaterialNotesImages
Aerotitan A. sudamericanusBajo de ArriagadaUpperPartial rostrumThe first unambiguous azhdarchid from South-America [20]
Aerotitan.jpg

Fish

Fish reported from the Allen Formation [3]
GenusSpeciesLocationStratigraphic positionMaterialNotesImages
Ceratodontiformes indeterminate3 tooth plates
Chondrichthyes indeterminate11 vertebral centra
Diplomystidae indeterminate4 incomplete pectoral spines
Siluriformes indeterminate5 incomplete pectoral spines
Lepisosteidae indeterminate6 vertebral centra
Teleostei indeterminate10 isolated teeth
cf. Percichthyidae indeterminate19 fragmentary vertebrae

Squamata

Squamates reported from the Allen Formation [3]
GenusSpeciesLocationStratigraphic positionMaterialNotesImages
PatagoniophisP. parvusincomplete trunk vertebra
Alamitophis A. argentinusincomplete trunk vertebra
Madtsoiidae indeterminateincomplete trunk vertebra

Rhynchocephalia

Rhynchocephalia reported from the Allen Formation
GenusSpeciesLocationStratigraphic positionMaterialNotesImages
Lamarquesaurus L. cabazaiCerro Tortuga [21]

Plesiosauria

Plesiosaurs reported from the Allen Formation
GenusSpeciesLocationStratigraphic positionMaterialNotesImages
Kawanectes K. lafquenianum

Frogs

Unnamed frogs belonging to the family Calyptocephalellidae and Leptodactylidae, and those with no family designation were also found. [22] [3]

Frogs reported from the Allen Formation
GenusSpeciesLocationStratigraphic positionMaterialNotesImages
Kuruleufenia K. xenopoides Pipid frog. [23]

Mammals

The mammal fauna of the Allen Formation is known from seven teeth, which document the presence of several species. [24]

Mammals reported from the Allen Formation
GenusSpeciesLocationMaterialNotesImages
Mesungulatum M. lamarquensisCerro TortugaTwo upper molars and a fragmentary lower molarA dryolestoid
Groebertherium G. stipaniciciCerro TortugaOne upper molarA dryolestoid
cf. Brandonia sp.Cerro TortugaOne lower molarA dryolestoid
Barberenia B. allenensisCerro TortugaOne upper molariformA dryolestoid
Solanutheirum S. walshiCerro TortugaA right lower molar and left dentary fragment.A meridiolestid. [25]
Trapalcotherium T. matuastensisCerro TortugaOne first lower molarA gondwanathere

Plants

Plants reported from the Allen Formation
GenusSpeciesLocationStratigraphic positionMaterialNotesImages
Podocarpoxylon P. mazzoniiValcheta Petrified Forest, Río Negro Province. [26] Fossil wood. [26]

See also

Related Research Articles

<i>Bonitasaura</i> Extinct genus of dinosaurs

Bonitasaura is a genus of titanosaurian dinosaur hailing from uppermost layers of the Late Cretaceous (Santonian) Bajo de la Carpa Formation, Neuquén Group of the eastern Neuquén Basin, located in Río Negro Province, Northwestern Patagonia, Argentina. The remains, consisting of a partial sub-adult skeleton jumbled in a small area of fluvial sandstone, including a lower jaw with teeth, a partial vertebrae series, and limb bones, were described by Sebastian Apesteguía in 2004.

<i>Notohypsilophodon</i> Extinct genus of dinosaurs

Notohypsilophodon is a genus of ornithopod dinosaur from the Late Cretaceous of Argentina. It was described as the only "hypsilophodont" known from South America, although this assessment is not universally supported, and Gasparinisaura is now believed to have been a basal euornithopod as well.

<i>Quilmesaurus</i> Extinct genus of dinosaurs

Quilmesaurus is a genus of carnivorous abelisaurid theropod dinosaur from the Patagonian Upper Cretaceous of Argentina. It was a member of Abelisauridae, closely related to genera such as Carnotaurus. The only known remains of this genus are leg bones which share certain similarities to a variety of abelisaurids. However, these bones lack unique features, which may render Quilmesaurus a nomen vanum.

<i>Talenkauen</i> Extinct genus of dinosaurs

Talenkauen is a genus of basal iguanodont dinosaur from the Campanian or Maastrichtian age of the Late Cretaceous Cerro Fortaleza Formation, formerly known as the Pari Aike Formation of Patagonian Lake Viedma, in the Austral Basin of Santa Cruz, Argentina. It is based on MPM-10001A, a partial articulated skeleton missing the rear part of the skull, the tail, and the hands. The type and only species is Talenkauen santacrucensis.

<span class="mw-page-title-main">Candeleros Formation</span> Geologic formation in Argentina

The Candeleros Formation is a geologic formation that crops out in the Río Negro, Neuquén, and Mendoza provinces of northern Patagonia, Argentina. It is the oldest formation in the Neuquén Group and belongs to the Rio Limay Subgroup. Formerly that subgroup was treated as a formation, and the Candeleros Formation was known as the Candeleros Member.

<i>Rocasaurus</i> Genus of titanosaurian sauropod from the Late Cretaceous period

Rocasaurus is a genus of titanosaurian sauropod that lived in South America. Rocasaurus was discovered in Argentina in 2000, within the Allen Formation which is dated to be middle Campanian to early Maastrichtian in age. This genus grew up to 8 metres (26 ft) long, making it one of the smaller sauropods. It seems to be closely related to saltasaurid dinosaurs, like Saltasaurus and Neuquensaurus.

The Huincul Formation is a geologic formation of Late Cretaceous age of the Neuquén Basin that outcrops in the Mendoza, Río Negro and Neuquén Provinces of northern Patagonia, Argentina. 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.

<span class="mw-page-title-main">Bajo de la Carpa Formation</span> Geological formation in Argentina

The Bajo de la Carpa Formation is a geologic formation of the Neuquén Basin that crops out in northern Patagonia, in the provinces of Río Negro and Neuquén, Argentina. It is the oldest of two formations belonging to the Río Colorado Subgroup within the Neuquén Group. Formerly, that subgroup was treated as a formation, and the Bajo de la Carpa Formation was known as the Bajo de la Carpa Member.

<span class="mw-page-title-main">La Colonia Formation</span> Geological formation in Argentina

The La Colonia Formation is a geological formation in Argentina whose strata date back to the Late Cretaceous. Dinosaur remains are among the fossils that have been recovered from the formation.

<span class="mw-page-title-main">Chorrillo Formation</span> Geologic formation in southern Patagonia, Argentina

The Chorrillo Formation, also named as Chorillo Formation, is a Maastrichtian geologic formation in southern Patagonia, Argentina. The formation is more than 50 metres (160 ft) thick and underlies the Calafate Formation and rests on top of the La Irene Formation.

<i>Bonapartenykus</i> A large alvarezsauroid dinosaur

Bonapartenykus is a monospecific genus of alvarezsauroid dinosaur from Argentina that lived during the Late Cretaceous (Campanian-Maastrichtian) in what is now the upper Allen Formation of the Río Negro Province. The type and only species, Bonapartenykus ultimus, is known from a nearly articulated but partial skeleton that was found in close association to two incomplete eggs and several clusters of eggshells belonging to the oogenus Arriagadoolithus. Bonapartenykus was named in 2012 by Federico L. Agnolin, Jaime E. Powell, Fernando E. Novas and Martin Kundrát. Bonapartenykus has an estimated length of 2.5 m (8.2 ft) and weight of 72 kg (159 lb), making it the largest member of the clade Alvarezsauroidea.

Tralkasaurus is a genus of abelisaurid dinosaur from the Huincul Formation from Río Negro Province in Argentina. The type and only species is Tralkasaurus cuyi, named in 2020 by Mauricio Cerroni and colleagues based on an incomplete skeleton. A medium-sized abelisaurid, Tralkasaurus exhibits a conflicting blend of characteristics found among the early-diverging abelisauroids with others that characterize the highly specialized clade Brachyrostra, and thus its position within the clade is poorly-resolved.

Kaikaifilusaurus is an extinct genus of rhynchocephalians in the family Sphenodontidae from the Late Cretaceous of South America. Fossils of the genus were found in Cenomanian sediments of the Candeleros Formation and Turonian layers of the Huincul Formation, both of the Neuquén Basin and the Albian strata of the Cerro Barcino Formation in the Cañadón Asfalto Basin, all in Patagonia, Argentina. The genus contains two species, K. minimus and the type species K. calvoi.

<i>Niebla antiqua</i> Extinct species of dinosaur

Niebla is a genus of abelisaurid theropod dinosaur from the Late Cretaceous Period (Campanian-Maastrichtian) of Río Negro province, Argentina. The genus contains a single species, Niebla antiqua, and is known from a partial, non-articulated skeleton. The holotype, found in the Allen Formation, represents an adult individual about nine years old in minimum age.

<i>Meraxes</i> Genus of carcharodontosaurid dinosaurs

Meraxes is a genus of large carcharodontosaurid theropod dinosaur from the Late Cretaceous Huincul Formation of Patagonia, Argentina. The genus contains a single species, Meraxes gigas.

<i>Patagopelta</i> Genus of nodosaurid dinosaurs

Patagopelta is an extinct genus of ankylosaurian dinosaur from the Late Cretaceous Allen Formation of Argentina. The genus contains a single species, P. cristata, known from a partial skeleton. While originally described as a nodosaurine, later discoveries provided support for parankylosaurian affinities for the taxon. Patagopelta is a very small ankylosaur, comparable in size to the dwarf nodosaurid Struthiosaurus, about 2 m (6.6 ft) long.

<i>Chucarosaurus</i> Genus of titanosaurian dinosaurs

Chucarosaurus is an extinct genus of titanosaurian dinosaur from the Late Cretaceous Huincul Formation of Argentina. The genus contains a single species, C. diripienda, known from various limb and pelvic bones.

Sidersaura is an extinct genus of rebbachisaurid sauropod dinosaur from the Late Cretaceous Huincul Formation of Argentina. The genus contains a single species, S. marae, known from the remains of four individuals. Sidersaura represents one of the largest known rebbachisaurids.

<i>Chakisaurus</i> Extinct genus of ornithopod dinosaurs

Chakisaurus is an extinct genus of elasmarian ornithopod dinosaur from the Late Cretaceous Huincul Formation of Argentina. The genus contains a single species, C. nekul, known from multiple partial skeletons belonging to individuals of different ages. Chakisaurus represents the first ornithischian species to be named from the Huincul Formation.

References

  1. Salgado et al., 2007
  2. Weishampel, David B; et al. (2004). "Dinosaur distribution (Late Cretaceous, South America)." In: Weishampel, David B.; Dodson, Peter; and Osmólska, Halszka (eds.): The Dinosauria, 2nd, Berkeley: University of California Press. Pp. 600-604. ISBN   0-520-24209-2.
  3. 1 2 3 4 Martinelli, A. and Forasiepi, A.M. (2004). "Late Cretaceous vertebrates from Bajo de Santa Rosa (Allen Formation), Rio Negro province, Argentina, with the description of a new sauropod dinosaur (Titanosauridae)". Revista del Museo Argentino de Ciencias Naturales 6(2): 257–305.
  4. 1 2 Armas & Sánchez, 2015, p.101
  5. Armas & Sánchez, 2015, p.110
  6. 1 2 3 4 5 6 7 8 Weishampel et al., 2004, p.604
  7. Arbour, Victoria M.; Currie, Philip J. (2016-05-03). "Systematics, phylogeny and palaeobiogeography of the ankylosaurid dinosaurs". Journal of Systematic Palaeontology. 14 (5): 385–444. Bibcode:2016JSPal..14..385A. doi:10.1080/14772019.2015.1059985. ISSN   1477-2019. S2CID   214625754.
  8. Riguetti, Facundo; Pereda-Suberbiola, Xabier; Ponce, Denis; Salgado, Leonardo; Apesteguía, Sebastián; Rozadilla, Sebastián; Arbour, Victoria (2022-12-31). "A new small-bodied ankylosaurian dinosaur from the Upper Cretaceous of North Patagonia (Río Negro Province, Argentina)". Journal of Systematic Palaeontology. 20 (1): 2137441. Bibcode:2022JSPal..2037441R. doi:10.1080/14772019.2022.2137441. ISSN   1477-2019. S2CID   254212751.
  9. Rozadilla, S.; Brissón-Egli, F.; Agnolín, F.L.; Aranciaga-Rolando, A.M.; Novas, F.E. (2022). "A new hadrosaurid (Dinosauria: Ornithischia) from the Late Cretaceous of northern Patagonia and the radiation of South American hadrosaurids". Journal of Systematic Palaeontology. 19 (17): 1207–1235. doi:10.1080/14772019.2021.2020917. S2CID   247122005.
  10. Coria et al., 2012
  11. Juárez Valieri et al., 2010
  12. 1 2 "63.10 Provincia de Río Negro, Argentina; 4. Río Colorado Formation," in Weishampel, et al. (2004). Page 604.
  13. Rolando et al., 2022
  14. 1 2 "Table 13.1," in Weishampel, et al., 2004, p.269
  15. "Table 13.1," in Weishampel, et al., 2004, p.270
  16. Agnolin, 2010
  17. "Table 11.1," in Weishampel, et al., 2004, p.215
  18. Aranciaga Rolando, Mauro; Cerroni, Mauricio A.; Garcia Marsà, Jordi A.; Agnolín, Federico l.; Motta, Matías J.; Rozadilla, Sebastián; Brisson Eglí, Federico; Novas, Fernando E. (2020-10-14). "A new medium-sized abelisaurid (Theropoda, Dinosauria) from the late cretaceous (Maastrichtian) Allen Formation of Northern Patagonia, Argentina". Journal of South American Earth Sciences. 105: 102915. doi:10.1016/j.jsames.2020.102915. hdl: 11336/150468 . ISSN   0895-9811. S2CID   225123133.
  19. "Table 4.1," in Weishampel, et al., 2004, p.77
  20. Novas et al., 2012
  21. Apesteguía & Rougier, 2007, p.3
  22. Suazo Lara, F.; Gómez, R. O. (2022-03-01). "In the shadow of dinosaurs: Late Cretaceous frogs are distinct components of a widespread tetrapod assemblage across Argentinean and Chilean Patagonia" . Cretaceous Research. 131: 105085. Bibcode:2022CrRes.13105085S. doi:10.1016/j.cretres.2021.105085. ISSN   0195-6671. S2CID   243482426.
  23. Gómez, Raúl O. (2016-07-01). "A new pipid frog from the Upper Cretaceous of Patagonia and early evolution of crown-group Pipidae". Cretaceous Research. 62: 52–64. Bibcode:2016CrRes..62...52G. doi:10.1016/j.cretres.2016.02.006. hdl: 11336/59544 . ISSN   0195-6671.
  24. Rougier et al., 2009
  25. Connelly, B. E.; Cardozo, M. S.; Montgomery, J. D.; Rougier, G. W. (2024). "New mammals from the Upper Cretaceous Allen Formation (Patagonia, Argentina) and reassessment of meridiolestidan diversity". Cretaceous Research. 162. 105935. doi:10.1016/j.cretres.2024.105935.
  26. 1 2 Passalia, M. G.; Garrido, A.; Iglesias, A.; Vera, E. I. (2022-10-14). "The Valcheta Petrified Forest (Upper Cretaceous), Northern Patagonia, Argentina: A Geological And Paleobotanical Survey" . Cretaceous Research. 142: 105395. doi:10.1016/j.cretres.2022.105395. ISSN   0195-6671. S2CID   252964524.

Bibliography

Further reading