Allen Formation

Last updated
Allen Formation
Stratigraphic range: Mid Campanian-Maastrichtian
~73–69  Ma
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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 Formation Allen Formation Fauna.png
Fauna of Allen Formation

Uliana and Dellapé defined the formation's stratotype in 1981 in the eastern area of the Bajo de Añelo, where the relation between the base and top is clearly exposed. The deposits are mostly clastic, interbedded with banks of limestone and layers of anhydrite, which were defined as 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]

Armas and Sánchez performed a detailed facies analysis of the formation 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

Ankylosaurs
GenusSpeciesLocationStratigraphic positionMaterialNotesImages
Patagopelta P. cristataSalitral Moreno localityLowerTooth, three posterior dorsal vertebrae, caudal vertebrae, two caudal centra, right femur, partial cervical half ring, and osteoderms.A parankylosaur [7]
Patagopelta into the water.png
Hadrosaurs
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 [8]
Kelumapusaura.jpg
Lapampasaurus L. cholinoiLowerElements of the axial and appendicular skeleton of a subadult individualA hadrosaur [9]
Willinakaqe W. salitralensisSalitral Moreno site.LowerA right premaxilla.A saurolophine hadrosaur [10]

Saurischians

Sauropods
GenusSpeciesLocationStratigraphic positionMaterialNotesImages
Aeolosaurus IndeterminateLowerA titanosaur [6]
Aeolosaurus-rionegrinus-JD-2020-1.png

Bonatitan

B.reigi [11]

LowerBraincases, caudal vertebrae, and several limb elementsA titanosaur [11]
Menucocelsior M. arriagadaiLowerSeventeen caudal vertebrae and several appendicular bones: a right humerus, a left fibula and some metapodial.A titanosaur [12]
Panamericansaurus P. schroederi"Five tail vertebrata, sacral vertebrae, left humerus and rib fragments"A titanosaur [6] [13]
Pellegrinisaurus?P. powelliLower (if it is from the formation)"Dorsal and caudal vertebrae, partial femur"A titanosaur [6] [13]
Pellegrinisaurus Skeleton reconstruction.jpg
Rocasaurus R. munioziLower"Partial postcranial skeleton"A titanosaur [6] [14]

Theropods

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 [15]
Limenavis L. patagonicaLower"Partial forelimb"An ornithuran [6] [16]
Niebla N. antiquaUpperBraincase, fragmentary jaw and teeth, relatively complete scapulocoracoid, dorsal ribs, and incomplete vertebrae.An abelisaurid [17]
Abelisauridae-Niebla-antiqua.jpg
Quilmesaurus Q. currieiUpperFemur and distal tibiaAn abelisaurid [6] [18]
Quilmesaurus curriei.jpg

Pterosaurs

Fragmentary fossils are known from the formation. [6]

GenusSpeciesLocationStratigraphic positionMaterialNotesImages
Aerotitan A. sudamericanusBajo de ArriagadaUpperPartial rostrumThe first unambiguous azhdarchid from South-America [19]
Aerotitan.jpg

Fish

Genus [3] SpeciesLocationStratigraphic positionMaterialNotesImages
Atlantoceratodus A. patagonicus3 tooth platesA ceratorontiform lungfish [20]
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

Genus [3] SpeciesLocationStratigraphic positionMaterialNotesImages
Patagoniophis P. parvusincomplete trunk vertebra
Alamitophis A. argentinusincomplete trunk vertebra
Madtsoiidae indeterminateincomplete trunk vertebra

Turtles

GenusSpeciesLocationStratigraphic positionMaterialNotesImages
Iaremys I. batrachomorphaA chelid turtle [21]
Yaminuechelys Y. gasperiniiA chelid turtle

Rhynchocephalia

GenusSpeciesLocationStratigraphic positionMaterialNotesImages
Lamarquesaurus L. cabazaiCerro Tortuga [22]

Plesiosauria

GenusSpeciesLocationStratigraphic positionMaterialNotesImages
Kawanectes K. lafquenianum

Frogs

Unnamed frogs belonging to the family Calyptocephalellidae and Leptodactylidae, and those with no family designation were also found. [23] [3]

GenusSpeciesLocationStratigraphic positionMaterialNotesImages
Calyptocephalella C. satan Calyptocephalellid frog [24]
Kuruleufenia K. xenopoides Pipid frog [25]

Mammals

The mammal fauna of the Allen Formation is known from seven teeth, which document the presence of several species. [26]

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. [27]
Trapalcotherium T. matuastensisCerro TortugaOne first lower molarA gondwanathere

Plants

GenusSpeciesLocationStratigraphic positionMaterialNotesImages
Podocarpoxylon P. mazzoniiValcheta Petrified Forest, Río Negro Province. [28] Fossil wood [28]

See also

Related Research Articles

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

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

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<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.

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

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<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>Yatenavis</i> Extinct genus of birds

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<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.

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

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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. Soto Acuña, Sergio; Vargas, Alexander O.; Kaluza, Jonatan (2024). "A new look at the first dinosaur discovered in Antarctica: reappraisal of Antarctopelta oliveroi (Ankylosauria: Parankylosauria)". Advances in Polar Science. 35 (1): 78–107. doi: 10.12429/j.advps.2023.0036 .
  8. 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.
  9. Coria et al., 2012
  10. Juárez Valieri et al., 2010
  11. 1 2 "63.10 Provincia de Río Negro, Argentina; 4. Río Colorado Formation," in Weishampel, et al. (2004). Page 604.
  12. Rolando et al., 2022
  13. 1 2 "Table 13.1," in Weishampel, et al., 2004, p.269
  14. "Table 13.1," in Weishampel, et al., 2004, p.270
  15. Agnolin, 2010
  16. "Table 11.1," in Weishampel, et al., 2004, p.215
  17. 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.
  18. "Table 4.1," in Weishampel, et al., 2004, p.77
  19. Novas et al., 2012
  20. Federico Agnolin (2010). "A new species of the genus Atlantoceratodus (Dipnoiformes: Ceratodontoidei) from the Uppermost Cretaceous of Patagonia and a brief overview of fossil dipnoans from the Cretaceous and Paleogene of South America". Brazilian Geographical Journal: Geosciences and Humanities Research Medium. 1 (2): 162–210.
  21. Agnolín, F. L.; Aranciaga-Rolando, A. M.; Ortiz, R. (2024). "New chelid turtle with a flattened skull from the Late Cretaceous of Northern Patagonia, Argentina". Alcheringa: An Australasian Journal of Palaeontology. doi:10.1080/03115518.2024.2427261.
  22. Apesteguía & Rougier, 2007, p.3
  23. 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.
  24. Federico Agnolin (2012). "A new Calyptocephalellidae (Anura, Neobatrachia) from the Upper Cretaceous of Patagonia, Argentina, with comments on its systematic position". Studia Geologica Salmanticensia. 48 (2): 129–178.
  25. 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.
  26. Rougier et al., 2009
  27. 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.
  28. 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