The Allen Formation is a geological formation in Argentina whose strata date back to the Late Cretaceous (middle Campanian to early Maastrichtian. 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]
Description
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.
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.
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.
A study of pollen found in outcrops of the middle member of the Allen Formation supported a late Maastrichtian age for these layers.[6]
Fossil content
Dinosaurs
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Color key
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Notes
Uncertain or tentative taxa are in small text; crossed out taxa are discredited.
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Dinosaur eggs are known from the formation.[7]
Ornithischians
- Ankylosaurs
| Genus
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Species
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Location
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Stratigraphic position
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Material
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Notes
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Images
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| Ankylosauria[8]
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Indeterminate
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Arriagada Farm
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Two teeth, five osteoderms, and a partial sacrum
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Fossil remains possibly belonging to a parankylosaur distinct from Patagopelta
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| Patagopelta
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P. cristata
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Salitral Moreno locality
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Lower
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Tooth, three posterior dorsal vertebrae, caudal vertebrae, two caudal centra, right femur, partial cervical half ring, and osteoderms
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A possible parankylosaur[9]
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- Hadrosaurs
| Genus
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Species
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Location
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Stratigraphic position
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Material
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Notes
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Images
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| Bonapartesaurus
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B. rionegrensis
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Salitral Moreno and Islas Malvinas.
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Lower
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A partial skeleton.
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A hadrosaur
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| Kelumapusaura
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K. machi
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Cerro Matadero, Arriagada Farm
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Upper
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Partial skull, a cervical vertebrae, several sacrals, sternal rib and sternal plate, and multiple referred specimens found in a bonebed
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A saurolophine hadrosaur[10]
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| Lapampasaurus
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L. cholinoi
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Islas Malvinas
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Lower
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Elements of the axial and appendicular skeleton of a subadult individual
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A hadrosaur
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| Willinakaqe
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W. salitralensis
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Salitral Moreno site.
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Lower
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A right premaxilla.
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A saurolophine hadrosaur[12]
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Saurischians
- Sauropods
| Genus
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Species
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Location
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Stratigraphic position
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Material
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Notes
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Images
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| Aeolosaurus
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Indeterminate
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Lower
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A titanosaur[7]
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Bonatitan
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B.reigi[13]
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Lower
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Braincases, caudal vertebrae, and several limb elements
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A titanosaur[13]
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| Menucocelsior
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M. arriagadai
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Lower
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Seventeen caudal vertebrae and several appendicular bones: a right humerus, a left fibula and some metapodial.
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A titanosaur
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| Panamericansaurus
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P. schroederi
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"Five tail vertebrata, sacral vertebrae, left humerus and rib fragments"
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A titanosaur[7][15]
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| Pellegrinisaurus?
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P. powelli
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Lower (if it is from the formation)
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"Dorsal and caudal vertebrae, partial femur"
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A titanosaur[7][15]
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| Rocasaurus
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R. muniozi
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Middle
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"Partial postcranial skeleton"
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A titanosaur[7][16]
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Theropods
| Genus
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Species
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Location
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Stratigraphic position
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Material
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Notes
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Images
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| Austroraptor
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A. cabazai
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Lower
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A fragmentary skeleton including parts of the skull, lower jaw, a few neck and torso vertebrae, some ribs, a humerus, and assorted bones from both legs
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A dromaeosaurid
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| Bonapartenykus
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B. ultimus
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Upper
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A 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.
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An alvarezsauroid
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| Lamarqueavis
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L. australis
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Lower
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"Right coracoid with damaged sternal and omal extremities, and lacking acrocoracoidal process"
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An ornithuran[17]
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| Limenavis
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L. patagonica
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Lower
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"Partial forelimb"
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An ornithuran[7][18]
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| Niebla
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N. antiqua
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Upper
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Braincase, fragmentary jaw and teeth, relatively complete scapulocoracoid, dorsal ribs, and incomplete vertebrae.
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An abelisaurid[19]
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| Quilmesaurus
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Q. curriei
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Upper
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Femur and distal tibia
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An abelisaurid[7][20]
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Pterosaurs
Fragmentary fossils are known from the formation.[7]
| Genus
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Species
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Location
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Stratigraphic position
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Material
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Notes
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Images
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| Aerotitan
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A. sudamericanus
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Bajo de Arriagada
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Upper
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Partial rostrum
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The first unambiguous azhdarchid from South-America
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Fish
Squamata
| Genus[3][24]
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Species
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Location
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Stratigraphic position
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Material
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Notes
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Images
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| Alamitophis
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A. argentinus
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incomplete trunk vertebra
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| Madtsoiidae
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indeterminate
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incomplete trunk vertebra
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| Paleoteius [25]
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P. lakui
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Bonapartenykus site on Arriagada Farm
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Upper
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A specimen consists of a partial skull and skeleton belonging to a single individual.
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A lizard
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| Patagoniophis
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P. parvus
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incomplete trunk vertebra
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| Pleurodonta
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indeterminate
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incomplete left maxilla
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| ?Scincoidea
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indeterminate
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incomplete left maxilla
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| Teiioidea
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indeterminate
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incomplete right maxilla
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Turtles
Rhynchocephalia
| Genus
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Species
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Location
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Stratigraphic position
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Material
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Notes
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Images
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| Lamarquesaurus
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L. cabazai
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Cerro Tortuga
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[28] |
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Plesiosauria
| Genus
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Species
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Location
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Stratigraphic position
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Material
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Notes
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Images
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| Kawanectes
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K. lafquenianum
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Quarry of the “Bentonitas Patagónicas” company
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Upper
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A partial skeleton consists of six cervical vertebrae, three dorsal vertebrae, three sacral vertebrae, nine caudal vertebrae, right femur, right humerus, ilium, one 216 mesopodial element, one caudal phalanx and one caudal rib .
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An elasmosaur.
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Frogs
Unnamed frogs belonging to the family Calyptocephalellidae and Leptodactylidae, and those with no family designation were also found.[29][3]
Mammals
The mammal fauna of the Allen Formation is known from seven teeth, which document the presence of several species.[32]
| Genus |
Species |
Location |
Material |
Notes |
Images
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| Mesungulatum
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M. lamarquensis
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Cerro Tortuga
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Two upper molars and a fragmentary lower molar
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A dryolestoid
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| Groebertherium
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G. stipanicici
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Cerro Tortuga
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One upper molar
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A dryolestoid
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| cf. Brandonia
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sp.
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Cerro Tortuga
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One lower molar
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A dryolestoid
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| Barberenia
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B. allenensis
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Cerro Tortuga
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One upper molariform
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A dryolestoid
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| Solanutheirum
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S. walshi
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Cerro Tortuga
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A right lower molar and left dentary fragment.
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A meridiolestid.[33]
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| Trapalcotherium
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T. matuastensis
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Cerro Tortuga
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One first lower molar
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A gondwanathere
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Plants
| Genus |
Species |
Location
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Stratigraphic position
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Material |
Notes |
Images
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| Podocarpoxylon
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P. mazzonii
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Valcheta Petrified Forest, Río Negro Province.[34]
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Lower
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Fossil wood[34]
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A conifer tree
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| Wintucycas[35]
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W. stevensonii
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Salitral Ojo de Agua, Río Negro Province.
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Lower
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Silicificated cycad trunks
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An encephalartoid cycad
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See also
References
- ^ 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.
- ^ a b c d Martinelli, Agustín; Forasiepi, Analía (2004). "Late Cretaceous vertebrates from bajo de Santa Rosa (Allen Formation), Río Negro province, Argentina, with the description of a new sauropod dinosaur (Titanosauridae)". Revista del Museo Argentino de Ciencias Naturales. 6 (2): 257–305. doi:10.22179/REVMACN.6.88.
- ^ Pincheira, Egly Pérez; Garrido, Alberto Carlos (November 2024). "Palynostratigraphy from the Allen and Jagüel formations at the Cerro Gutiérrez locality, Lago Pellegrini area, South Argentina". Journal of South American Earth Sciences. 148 105139. Bibcode:2024JSAES.14805139P. doi:10.1016/j.jsames.2024.105139.
- ^ a b c d e f g h Weishampel et al., 2004, p.604
- ^ Álvarez Nogueira, Rodrigo; Agnolín, Federico L.; Rozadilla, Sebastián; Aranciaga-Rolando, Mauro; Novas, Fernando E. (2 January 2025). "Ankylosaurian remains from a new Campanian–Maastrichtian locality in Northern Patagonia, Argentina". Alcheringa: An Australasian Journal of Palaeontology. 49 (1): 69–78. Bibcode:2025Alch...49...69A. doi:10.1080/03115518.2025.2467462.
- ^ 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.
- ^ Rozadilla, Sebastián; Brissón-Egli, Federico; Agnolín, Federico Lisandro; Aranciaga-Rolando, Alexis Mauro; Novas, Fernando Emilio (2 September 2021). "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. Bibcode:2021JSPal..19.1207R. doi:10.1080/14772019.2021.2020917.
- ^ Juárez Valieri et al., 2010
- ^ a b "63.10 Provincia de Río Negro, Argentina; 4. Río Colorado Formation," in Weishampel, et al. (2004). Page 604.
- ^ a b "Table 13.1," in Weishampel, et al., 2004, p.269
- ^ "Table 13.1," in Weishampel, et al., 2004, p.270
- ^ Agnolin, 2010
- ^ "Table 11.1," in Weishampel, et al., 2004, p.215
- ^ Aranciaga Rolando, Mauro; Cerroni, Mauricio A.; Garcia Marsà, Jordi A.; Agnolín, Federico l.; Motta, Matías J.; Rozadilla, Sebastián; Brisson Eglí, Federico; Novas, Fernando E. (January 2021). "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. Bibcode:2021JSAES.10502915A. doi:10.1016/j.jsames.2020.102915. hdl:11336/150468.
- ^ "Table 4.1," in Weishampel, et al., 2004, p.77
- ^ 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.
- ^ Sergio Bogan; Louis Taverne; Federico L. Agnolin (2011). "Description of a new aspidorhynchid fish, Belonostomus lamarquensis sp. nov. (Halecostomi, Aspidorhynchiformes), from the continental Upper Cretaceous of Patagonia, Argentina". Bulletin de l'Institut Royal des Sciences Naturelles de Belgique, Sciences de la Terre. 81: 235–245.
- ^ Garberoglio, F. F.; Gómez, R. O.; Apesteguía, S.; Rougier, G. W. (2024). "A Late Cretaceous lizard assemblage from the Allen Formation, northern Patagonia, Argentina". Historical Biology: An International Journal of Paleobiology. 37 (4): 950–962. doi:10.1080/08912963.2024.2344789.
- ^ Agnolín, Federico L.; Aranciaga-Rolando, Mauro; Álvarez-Herrera, Gerardo; Ezcurra, Martín D.; Rodríguez, Ana Moreno; Chafrat, Pablo; Vega, Nahuel; Scanferla, Agustín; Smith, Krister T.; Novas, Fernando E. (2026-02-28). "A new late Cretaceous squamate from Patagonia sheds light on Gondwanan diversity". Scientific Reports. doi:10.1038/s41598-026-40914-8. ISSN 2045-2322.
- ^ 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. 49: 79–84. doi:10.1080/03115518.2024.2427261.
- ^ Sterli, Juliana; Fuente, Marcelo S. De La; Cerda, Ignacio A. (April 2013). "A New Species of Meiolaniform Turtle and a Revision of the Late Cretaceous Meiolaniformes of South America". Ameghiniana. 50 (2): 240–256. Bibcode:2013Amegh..50..240S. doi:10.5710/amgh.16.01.2013.582.
- ^ Apesteguía & Rougier, 2007, p.3
- ^ Suazo Lara, F.; Gómez, R.O. (March 2022). "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.
- ^ 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.
- ^ Gómez, Raúl O. (July 2016). "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.
- ^ Rougier et al., 2009
- ^ 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. Bibcode:2024CrRes.16205935C. doi:10.1016/j.cretres.2024.105935.
- ^ a b Passalia, M.G.; Garrido, A.; Iglesias, A.; Vera, E.I. (February 2023). "The Valcheta Petrified Forest (Upper Cretaceous), northern Patagonia, Argentina: A geological and paleobotanical survey". Cretaceous Research. 142 105395. Bibcode:2023CrRes.14205395P. doi:10.1016/j.cretres.2022.105395.
- ^ Leandro Carlos Alcides Martinez; Analia Emilia Eva Artabe; Josefina Bodnar (2012). "A new cycad stem from the Cretaceous in Argentina and its phylogenetic relationships with other Cycadales". Botanical Journal of the Linnean Society. 170 (3): 436–458. doi:10.1111/j.1095-8339.2012.01300.x.
Bibliography
- Agnolin, Federico L (2010), "An avian coracoid from the Upper Cretaceous of Patagonia, Argentina", Studia Geologica Salmanticensia, 46 (2): 99–119, retrieved 2019-02-16
- Apesteguía, Sebastián; Rougier, Guillermo W. (2007). "A Late Campanian Sphenodontid Maxilla from Northern Patagonia". American Museum Novitates (3581): 1. doi:10.1206/0003-0082(2007)3581[1:ALCSMF]2.0.CO;2.
- Armas, Paula; Sánchez, María Lidia (30 January 2015). "Márgenes costeros híbridos de la Cuenca Neuquina (Formación Allen, Cretácico Superior, Argentina)". Andean Geology. 42 (1). Bibcode:2015AndGe..42a...6A. doi:10.5027/andgeoV42n1-a06.
- Coria, Rodolfo A.; Riga, Bernardo González; Casadío, Silvio (December 2012). "Un Nuevo Hadrosáurido (Dinosauria, Ornithopoda) de la Formación Allen, Provincia de la Pampa, Argentina". Ameghiniana. 49 (4): 552–572. Bibcode:2012Amegh..49..552C. doi:10.5710/AMGH.9.4.2012.487.
- Juárez Valieri, Rubén; Haro, José; Fiorelli, Lucas; Calvo, Jorge (2010). "A new hadrosauroid (Dinosauria: Ornithopoda) from the Allen Formation (Late Cretaceous) of Patagonia, Argentina". Revista del Museo Argentino de Ciencias Naturales. 12: 217–231. doi:10.22179/REVMACN.12.242. hdl:11336/147903.
- Novas, Fernando E.; Kundrat, Martin; Agnolín, Federico L.; Ezcurra, Martín D.; Ahlberg, Per Erik; Isasi, Marcelo P.; Arriagada, Alberto; Chafrat, Pablo (November 2012). "A new large pterosaur from the Late Cretaceous of Patagonia". Journal of Vertebrate Paleontology. 32 (6): 1447–1452. Bibcode:2012JVPal..32.1447N. doi:10.1080/02724634.2012.703979. hdl:11336/98097.
- Rougier, Guillermo W.; Chornogubsky, Laura; Casadio, Silvio; Arango, Natalia Paéz; Giallombardo, Andres (February 2009). "Mammals from the Allen Formation, Late Cretaceous, Argentina". Cretaceous Research. 30 (1): 223–238. Bibcode:2009CrRes..30..223R. doi:10.1016/j.cretres.2008.07.006. hdl:11336/103413.
- Salgado, Leonardo; Coria, Rodolfo A.; Magalhaes Ribeiro, Claudia M.; Garrido, Alberto; Rogers, Raymond; Simón, María E.; Arcucci, Andrea B.; Rogers, Kristina Curry; Carabajal, Ariana Paulina; Apesteguía, Sebastián; Fernández, Mariela; García, Rodolfo A.; Talevi, Marianella (June 2007). "Upper Cretaceous dinosaur nesting sites of Río Negro (Salitral Ojo de Agua and Salinas de Trapalcó-Salitral de Santa Rosa), northern Patagonia, Argentina". Cretaceous Research. 28 (3): 392–404. Bibcode:2007CrRes..28..392S. doi:10.1016/j.cretres.2006.06.007. hdl:11336/183909.
- Weishampel, David B.; Dodson, Peter; Osmólska, Halszka (2004), The Dinosauria, 2nd edition, Berkeley: University of California Press, pp. 1–880, ISBN 0-520-24209-2, retrieved 2019-02-21
{{citation}}: CS1 maint: publisher location (link)
Further reading
- O'gorman, José Patricio; Salgado, Leonardo; Gasparini, Zulma (March 2011). "Plesiosaurios de la Formación Allen (Campaniano-Maastrichtiano) en el Área del Salitral de Santa Rosa (Provincia de Río Negro, Argentina)". Ameghiniana. 48 (1): 129–135. Bibcode:2011Amegh..48..129O. doi:10.5710/AMGH.v48i1(308).