The Portezuelo Formation is a geologic formation of Late Cretaceous (Late Turonian to Early Coniacian) age, outcropping in the Mendoza, Río Negro and Neuquén provinces of Argentina.Portezuelo Formation at Fossilworks.org It is the fourth-oldest formation in the Neuquén Group and the older of the two formations in the Río Neuquén Subgroup. Formerly, that subgroup was treated as a formation, and the Portezuelo Formation was known as the Portezuelo Member.Sánchez et al., 2006
Description The type locality of the Portezuelo Formation is the mountain range known as Sierra del Portezuelo in Neuquén Province.Wichmann, 1929 This formation conformably overlies the Lisandro Formation of the Río Limay Subgroup. In the top layers it grades into the Plottier Formation, the younger formation within the Río Neuquén Subgroup.
Sandstones and siltstones, probably deposited under fluvial conditions, make up the Portezuelo Formation. There are also occasional cemented claystone deposits, as well as numerous paleosols (fossil soils). The formation varies between thick throughout its range.Leanza et al., 2004
Fossil content
Many dinosaur fossils have recently been described from this formation, as well as remains of several other types of animals: teleosteid fish including Leufuichthys ceratodontiform lungfish including Chaoceratodus abelisauroid theropods (A possible noasaurid and an abelisaurid) several other theropods, including a modern, possibly galliform bird ornithopods, including possible iguanodonts
Dinosaurs Ornithischians
Ornithischians of the Portezuelo Formation TaxaSpeciesLocalityStratigraphic unitMaterialNotesImagesMacrogryphosaurusM. gondwanicus The Mari Menuco lake An incomplete skeleton of an adult individual which includes an almost complete vertebral column, eight cervical vertebrae, 14 dorsal vertebrae (complete series), six sacral vertebrae, thirteen caudal vertebrae, a cervical rib, eleven dorsal ribs; nine haemal arches, sternum, right and left pelvic girdles, and three thoracic mineralized plates. An elasmarian ornithopod. Sauropods
Sauropods of the Portezuelo Formation TaxaSpeciesLocalityStratigraphic unitMaterialNotesImages Baalsaurus B. mansillai A mostly complete right dentaryA titanosaur Futalognkosaurus F. dukei Futalognko quarryAtlas, axis, five anterior, four middle, and three poste-rior cervicals; 10 dorsals; ribs; complete sacrum; bothilia; right pubis and ischium; and one anterior caudalA titanosaur Malarguesaurus M. florenciae Upper and Lower parts A holotype consists of tail vertebrae, chevrons, ribs, and limb bones A titanosaur Muyelensaurus M. pecheni Loma del Lindero site A braincase including partial frontal and parietal, basioccipital, incomplete basipterygoid process, supraoccipital, exoccipital, basisphenoidals tubers, orbitosphenoids, and incomplete parasphenoids.A titanosaur
Theropods Theropods of the Portezuelo Formation TaxaSpeciesLocalityStratigraphic unitMaterialNotesImagesElemgasemE. nubilus Sierra del Portezuelo Lower A holotype consists of partial axial and appendicular elements, including cervical and caudal vertebrae, right femur, left tibia, right and left fibula, left astragalus-calcaneum, metatarsals, and various pedal phalanges A abelisaur MegaraptorPaulina-Carabajal and Currie, 2017M. namunhuaiquiiSierra del Portezuelo A complete front limb, right ulna, and left manual phalanx.A megaraptorid NeuquenraptorAgnolin et al., 2006Porfiri et al., 2007N. argentinusSierra del Portezuelo A holotype consists of fragments of cervical vertebra, dorsal ribs, haemal arches, left proximal radius, right femur and distal tibia, proximal tarsals, and most of the foot of the left hindlimb.A dromaeosaurid Pamparaptor Agnolin et al., 2006Porfiri et al., 2007P. microsBaal QuarryA holotype consists of three metatarsals, a complete second toe including the ungual, and two phalanges each from the third and fourth toes from the left foot A dromaeosauridPatagonykusP. puertai Los Barriales Lake.An incomplete but well-preserved skeleton consists of multiple vertebrae, the coracoids, a partial forelimb, pelvic girdle, and hindlimbsAn alvarezsaur.Unenlagia Agnolin et al., 2006Porfiri et al., 2007U. comahuensisSierra del Portezuelo Upper A partial skeleton lacking the skull but including vertebrae, a sacrum, ribs, chevrons, a scapula, a humerus, a partial pelvis, a femur and a tibia A dromaeosauridU. paynemiliFutalognko siteUpper Several paratypes consists of a partial skeleton consisting of a humerus, vertebrae, claw, phalanx, and two pubes.
Crocodyliformes Reptiles of the Portezuelo Formation TaxaSpeciesLocalityStratigraphic unitMaterialNotesImagesComahuesuchusC. bonaparteiKellner, Alexander & Figueiredo, Rodrigo & CALVO, JORGE. (2023). A new species of Comahuesuchus Bonaparte, 1991 (Crocodyliformes: Notosuchia) from the Upper Cretaceous of Neuquén, Lake Barreales, Patagonia, Argentina. Anais da Academia Brasileira de Ciências. 95. 10.1590/0001-3765202320230179. s. The Futalognko quarry UpperA partially preserved (cranial-most region) of the right mandibleA notosuchian crocodylomorphs. LomasuchusL. palpebrosus Loma de la LataSkull and fragment of the left mandibular ramusA peirosaurid notosuchian. PatagosuchusP. anielensis Baal Quarry, Loma de la LataA fragmentary left dentary and splenial, the right maxilla and right jugal bone, a back vertebra, a back osteoderm and the right humerus.A peirosaurid crocodyliform.
Pterosaurs Pterosaurs of the Portezuelo Formation TaxaSpeciesLocalityStratigraphic unitMaterialNotesImagesArgentinadracoA. barrealensis Centro Paleontológico Lago Barreales UpperA single partial lower jaw, missing the rear endAn azdarchoid pterosaur.
Turtles Turtles of the Portezuelo Formation TaxaSpeciesLocalityStratigraphic unitMaterialNotesImagesBaalemysB. mansillai Baal Quarry, Lago Barreales Upper A shell A chelid turtlePortezueloemysM. S. de la Fuente. 2003. Two new pleurodiran turtles from the Portezuelo Formation (Upper Cretaceous) of Northern Patagonia, Argentina. Journal of Paleontology 77(3):559-575P. patagonica Sierra del Portezuelo Upper A partial shell A pleurodiran turtles ProchelidellaP. portezuelae Sierra del Portezuelo Upper A set of postcrania A pleurodiran turtles
See also List of fossil sites List of dinosaur bearing rock formations
References
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