Area Paleontologia

Santiago, Chile

Area Paleontologia

Santiago, Chile
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Several Upper Cretaceous plesiosaur specimens recovered from southernmost Chile are described here. These were collected from upper levels of the Dorotea Formation exposed on three different localities (Sierra Baguales, Cerro Castillo, and Dumestre). The new material includes the first record of Aristonectes (Plesiosauria, Elasmosauridae), previously recorded from Argentina, central Chile, and Antarctica. Additional specimens include associated postcranial skeletons as well as isolated elements. Among these, we recognize the presence of aristonectines in the three studied localities, while non-aristonectine elasmosaurids were only collected from Cerro Castillo. The specimen from Dumestre is remarkable by being a small-sized adult, indeterminate aristonectine, and could be related to known representatives from Antarctica. These new finds prove the abundance of aristonectines as well as intermediate elasmosaurids along the Magallanes Basin during the uppermost Cretaceous, while extreme long-necked elasmosaurids as well as polycotylids seems to be completely absent during this time span. This key record from southernmost Chile and its strategic placement in the middle part of the Weddellian Province gives the chance for complementing the paleobiogeography of Upper Cretaceous plesiosaurs from the Southern Hemisphere. As a first result, a faunal turnover is observed during the early Maastrichtian, when extreme (very-long necked) elasmosaurids and polycotylids disappeared from the austral record. Since the early Maastrichtian and towards the late Maastrichtian, aristonectines became differentially abundant along the southeastern Pacific and Antarctica, but moderately represented in the southwestern Atlantic. On contrary, intermediate elasmosaurids were scarce in the Antarctic-Pacific realm, but abundant in the Atlantic. The updated record of austral plesiosaurs suggest a first stage of interchange from the Northern into the Southern Hemisphere, and through the Atlantic seaway, at least since the Coniacian to the late Campanian-early Maastrichtian. During the early Maastrichtian, aristonectines were relatively frequent in the New Zealand-Antarctica archipelago, becoming abundant along southern South America during the late Maastrichtian. © 2015 Andean Geology All Rights Reserved.

Otero R.A.,Area Paleontologia | Rubilar-Rogers D.,Area Paleontologia | Yury-Yanez R.E.,University of Chile | Vargas A.O.,University of Chile | And 3 more authors.
Antarctic Science | Year: 2013

We describe a new chimaeriform fish, Callorhinchus torresi sp. nov., from the uppermost Cretaceous (late Maastrichtian) of the López de Bertodano Formation, Isla Marambio (Seymour Island), Antarctica. The material shows it is distinct from currently known fossil and extant species of the genus, whereas the outline of the tritors (abrasive surfaces of each dental plate) shows an intermediate morphology between earlier records from the Cenomanian of New Zealand and those from the Eocene of Isla Marambio. This suggests an evolutionary trend in tritor morphology in the lineage leading to modern callorhynchids, during the Late Cretaceous-Palaeogene interval. © 2012 Antarctic Science Ltd.

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.

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.

Cenizo M.,Area Paleontologia | Cenizo M.,Maimónides University | Noriega J.I.,CONICET | Reguero M.A.,Instituto Antártico 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.

Yury-Yanez R.E.,University of Chile | Otero R.A.,Area Paleontologia | Soto-Acuna S.,University of Chile | Suarez M.E.,Caldera Pharmaceuticals, Inc. | And 2 more authors.
Andean Geology | Year: 2012

Paleogene records of birds in the Eastern margin of the Pacific Ocean have increased in recent years, being almost exclusively restricted to fossil Sphenisciformes (penguins). New avian remains (Ornithurae, Neornithes) from Middle-to-Late Eocene levels of the Estratos de Algarrobo unit, in Algarrobo, central Chile, are disclosed in the present work. These new finds are significant in representing the first non-spheniscid bird remains of Middle to Late Eocene age, recovered in mid-latitudes of the eastern Pacific and probably belonging to a procelarid. It complements the regional record of Eocene birds, previously known only at high-latitudes such as Seymour Island (Antarctica) and Magallanes (Chile), and low-latitude locations in Peru.

Otero R.A.,Area Paleontologia | Soto-Acuna S.,Area Paleontologia | Soto-Acuna S.,University of Chile | Rubilar-Rogers D.,Area Paleontologia
Cretaceous Research | Year: 2012

An almost complete postcranial skeleton recovered from late Maastrichtian beds of central Chile, which can be confidently referred to the clade Elasmosauridae (Sauropterygia: Plesiosauroidea), is described. The material displays diagnostic characters separately observed in several known Late Cretaceous plesiosaurians from the Southern Hemisphere, particularly from the Weddellian Biogeographic Province. The phylogenetic analysis indicates that the material studied has close affinities with the genus . Aristonectes, while supports the position of the Late Cretaceous plesiosaurian . Kaiwhekea katiki as well as the inclusion of . Aristonectes parvidens (=" . Morturneria seymourensis" ) in a new clade (Aristonectinae) within the Elasmosauridae. This indicates that cryptoclidians are still restricted to the Middle-Upper Jurassic, and verifies that the family Aristonectidae is polyphyletic. The material studied represents a valuable source for comparison of the morphologic characters present in elasmosaurids from the Weddellian Province towards the end of the Cretaceous, shedding light on the evolution of derived members of this clade. © 2012 Elsevier Ltd.

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.

Otero R.A.,Consejo de Monumentos Nacionales | Parham J.F.,University of Alabama | Parham J.F.,California State University, Bakersfield | Soto-Acuna S.,University of Chile | And 2 more authors.
Cretaceous Research | Year: 2012

We report new specimens of Late Cretaceous (early Maastrichtian) reptiles collected from Algarrobo, central Chile. The Algarrobo fossils include the northernmost occurrence of marine turtles, articulated plesiosaur remains, and mosasaur teeth recognized in the Weddellian Biogeographic Province. The presence of articulated material and teeth of elasmosaurid plesiosaurs, mosasaur teeth, and postcranial remains of cf. dermochelyid sea turtles re-emphasizes an emerging picture of the composition of Maastrichtian marine reptiles in the Pacific Basin. The fossil reptiles suggest that the Algarrobo strata were deposited on a shallow marine shelf. Proximity to the coast is indirectly suggested by the presence of fossil wood. © 2011 Elsevier Ltd.

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.

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