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Santiago, Chile

Otero R.A.,University of Chile | Gutstein C.S.,University of Chile | Vargas A.,University of Chile | Rubilar-Rogers D.,Area Paleontologia | And 3 more authors.
Journal of Paleontology | Year: 2014

We present new records of chondrichthyans recovered from strata of Maastrichtian age of the López de Bertodano Formation, Seymour (=Marambio) Island, and from levels of latest Campanian age of the Santa Marta Formation, James Ross Island, both located in the eastern Antarctic Peninsula. The material from Marambio Island comprises an associated assemblage with the first records of an indeterminate odontaspidid different from Odontaspis, as well as the genera Pristiophorus, Squatina, Paraorthacodus, and the species Chlamydoselachus tatere from the López de Bertodano Formation. Also, the studied section provides a well-constrained age for several taxa already recognized in the López de Bertodano Formation only by scattered samples of Maastrichtian age for the first time. The assemblage from Marambio Island is representative of one of the latest environmental conditions during the end of the Cretaceous in the coastal seas of the Larsen Basin before major changes that began after the K/P boundary. In addition, the finds from James Ross Island comprise the southernmost records of the neoselachians Cretalamna sp., Centrophoroides sp., as well as the holocephalans Callorhinchus sp. and an indeterminate rhinochimaerid, extending the occurrence of some of these taxa into the late Campanian, being their oldest record of the Weddellian Biogeographic Province. © 2014, The Paleontological Society. Source

Otero R.A.,University of Chile | Soto-Acuna S.,University of Chile | Vargas A.O.,University of Chile | Rubilar-Rogers D.,Area Paleontologia | And 2 more authors.
Gondwana Research | Year: 2014

Three specimens of elasmosaurid plesiosaurs (Sauropterygia, Plesiosauria) from Upper Cretaceous beds of Antarctica are described here. These include postcranial remains of a single adult individual recovered from late Maastrichtian beds of Marambio (= Seymour) Island, possessing a distinctive combination of features: cervical vertebrae having centra with a triangular outline in transverse section, a vertical groove on the rostral and caudal edge of the neural spines, and a deep articulation over the neural arch for the following postzygapophysis, while the scapula shows an unusually large and anteriorly recurved dorsal process. This combination of features is unknown in any adult, postcranial elasmosaurid genus recovered to date in the Upper Cretaceous of the Weddellian Biogeographic Province and could represent a new form. Additional specimens from James Ross Island comprise the first record of an Aristonectinae (Plesiosauria, Elasmosauridae) in late Campanian beds, being the oldest known record of this sub-family. Finally, a third specimen from the same age and locality reveals the presence of very-long necked elasmosaurids with affinities to typical representatives from the Upper Cretaceous of the Northern Hemisphere. These findings add to the known diversity of Upper Cretaceous elasmosaurids in high latitudes of the Southern Hemisphere. © 2013 International Association for Gondwana Research. Source

Cenizo M.,Area Paleontologia | Cenizo M.,Maimonides University | Noriega J.I.,CONICET | Reguero M.A.,Instituto Antartico Argentino
Journal of Ornithology | Year: 2016

Antarctoboenus carlinii nov. gen. nov. sp. is a large-sized falconiform bird from the La Meseta Formation (Lower Eocene) at Seymour (Marambio) Island, West Antarctica. The holotypical tarsometatarsus was originally assigned to Falconidae and its affinities to Polyborinae were pointed out. Detailed osteological and comparative analyses of the Antarctic specimen allowed recognition of the new taxon as a member of stem group Falconidae, i.e. it is supposed to belong to the early radiation of the falconiform lineage. Antarctoboenus carlinii is distinguished from members of crown group Falconidae by having a very shallow sulcus extensorius, a large foramen vasculare distale, an undistinguishable tendinal attachment for the m. adductor digiti II, and short trochlea metatarsi II, among its main diagnostic characters. Purported phylogenetic relationships between A. carlinii and Polyborinae are based on plesiomorphic characters retained in the tarsometatarsus of the latter clade. Our conclusions reinforce the hypothesis about the Neotropical or Austral origin of Falconidae supported by previous molecular phylogenies. © 2016, Dt. Ornithologen-Gesellschaft e.V. Source

Abello M.A.,National University of La Plata | Rubilar-Rogers D.,Area Paleontologia
Ameghiniana | Year: 2012

In this con-tribution, a taxonomic review for the genus Abderites Ameghino is presented. A comparative morphological analysis of the teeth, including a review of the dental homology, was performed. The continuous quantitative characters were evaluated by means of a traditional morphometric analysis. As a result, three species were recognized for the Miocene of Argentina and Chile. From the eight species originally described by Ameghino, only A crispus Ameghino from the Colhuehuapian (early Miocene) of Argentina, and A. meridionalis Ameghino from the "Pinturan" and Santacrucian (late early Miocene) of Argentina, are considered valid species. In addition, this study allowed identification a new species, Abderites aisenense sp. nov., recorded in the Friasian s.s. and Colloncuran (middle Miocene) from Chile and Argentina respectively. A. pristinus (Ameghino) previously recognized as valid species, is considered nomen dubium. Source

Salazar C.,Area Paleontologia | Stinnesbeck W.,University of Heidelberg
Journal of Systematic Palaeontology | Year: 2015

The Baños del Flaco Formation in central Chile contains abundant and well-preserved Tithonian (Late Jurassic) and scarce Berriasian (Early Cretaceous) ammonites. At Rio Maitenes in Curicó Province an assemblage referred to 10 genera and 12 species is here described. Windhauseniceras internispinosum, Corongoceras alternans and Substeueroceras koeneni were mentioned previously, but not described and discussed. Aulacosphinctes proximus, Micracanthoceras spinulosum and Corongoceras evolutum are new records for the Baños del Flaco Formation. Pseudolissoceras cf. zitteli, Lithacoceras malarguense, Choicensisphinctes windhauseni, Catutosphinctes cf. americanensis, Virgatosphinctes scythicus and Micracanthoceras microcanthum are documented in Chile for the first time. Micracanthoceras spinulosum shows strong ontogenetic changes. Virgatosphinctes scythicus is a morphologically variable species and is synonymous with the South American species Virgatosphinctes andesensis, V. mendozanus, V. mexicanus and V. leñaensis. Windhauseniceras internispinosum is relatively abundant at Rio Maitenes but rare elsewhere; its morphology varies considerably during ontogeny. Virgatosphinctes aff. pseudolictor and V. cf. raja, both recorded from Argentina, and V. guadalupensis, are synonymous with L. malarguense; V. tenuilineatus is synonymous with C. windhauseni and Aulacosphinctes chilensis with A. proximus. Micracanthoceras lamberti and M. tapiai are junior synonymies of M. microcanthum. Windhauseniceras internispinosum and Corongoceras alternans are Tithonian index fossils for Chile and Argentina, whereas Virgatosphinctes scythicus and Micracanthoceras microcanthum are Tithonian index fossils for the Russian platform and Tethys, respectively. Their co-occurrence at Río Maitenes confirms that most of the Baños del Flaco Formation is Tithonian (Upper Jurassic). However, the presence of Substeueroceras koeneni demonstrates that the uppermost strata of the Baños del Flaco Formation should be referred to the Lower Cretaceous (Berriasian). © The Trustees of the Natural History Museum, London 2015. All Rights Reserved. Source

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