Allen Formation

Last updated
Allen Formation
Stratigraphic range: Mid Campanian-Maastrichtian
~73–69  Ma
O
S
D
C
P
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K
Pg
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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

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
Atlantoceratodus A. patagonicus3 tooth platesA Ceratorontiform lungfish [21]
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
Patagoniophis P. parvusincomplete trunk vertebra
Alamitophis A. argentinusincomplete trunk vertebra
Madtsoiidae indeterminateincomplete trunk vertebra

Turtles

Turtles reported from the Allen Formation
GenusSpeciesLocationStratigraphic positionMaterialNotesImages
Yaminuechelys Y. gasperiniiA chelid turtle

Rhynchocephalia

Rhynchocephalia reported from the Allen Formation
GenusSpeciesLocationStratigraphic positionMaterialNotesImages
Lamarquesaurus L. cabazaiCerro Tortuga [22]

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. [23] [3]

Frogs reported from the Allen Formation
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]

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. [27]
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. [28] Fossil wood. [28]

See also

Related Research Articles

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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. 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. 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.
  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