Papers by Claudia Montalvo
Journal of South American Earth Sciences, Aug 1, 2023
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Servicio Geológico Minero Argentino. Instituto de Geología y Recursos Minerales eBooks, 2008
Fil: Silva Nieto, Diego G. Ministerio de Planificacion Federal, Inversion Publica y Servicios. Se... more Fil: Silva Nieto, Diego G. Ministerio de Planificacion Federal, Inversion Publica y Servicios. Secretaria de Mineria. Servicio Geologico Minero Argentino (SEGEMAR); Argentina.
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Revista del Museo Argentino de Ciencias Naturales, 2002
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Revista del Museo de La Plata, 2020
La Facultad de Ciencias Exactas y Naturales de la Universidad Nacional de La Pampa, Santa Rosa, A... more La Facultad de Ciencias Exactas y Naturales de la Universidad Nacional de La Pampa, Santa Rosa, Argentina, custodia una importante colección paleontológica iniciada en el año 1987, cuyo acrónimo es GHUNLPam. En la actualidad, contiene alrededor de 35.000 especímenes de invertebrados, vertebrados, plantas, icnofósiles y palinomorfos, que provienen principalmente de diferentes niveles fosilíferos de la provincia de La Pampa. Se presenta un catálogo del material tipo de la colección de vertebrados, correspondiente en su mayoría a mamíferos del Mioceno tardío de esta provincia. Incluye los holotipos de 15 especies publicados hasta fin del año 2019, siendo cuatro de ellas las especies tipo de los géneros correspondientes. Para cada taxón, se proporciona la información taxonómica actualizada, las sinonimias, la diagnosis original, enmendada o ampliada, según el caso (traducida al español si se publicó originalmente en otro idioma), la localidad tipo, la procedencia geográfica y estratigrá...
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PALAIOS
ABSTRACTDiverse modifications of the original morphological features occur throughout the taphono... more ABSTRACTDiverse modifications of the original morphological features occur throughout the taphonomic history of osteological remains, which may lead in erroneous interpretations about the formation of an accumulation as well as taxonomic misidentifications. Here, we present a neo-taphonomic study in order to analyze and interpret the modifications generated by digestion on osteoderms of the armadillo Dasypus novemcinctus obtained from scats produced by Puma concolor. Results reveal intense breakage and modifications of the articular and broken edges, dorsal surface, bone tissues, and ornamentation pattern of the osteoderms. This work describes for the first time the modifications caused by digestion in armadillo osteoderms, improving the knowledge of preservation of this type of skeletal element and providing a modern analog that can be used to distinguish archeological and paleontological accumulations formed by predators from those generated by other processes. The recognition tha...
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La información tafonómica surgida de restos óseos de microvertebrados digeridos, contenidos en eg... more La información tafonómica surgida de restos óseos de microvertebrados digeridos, contenidos en egagrópilas de rapaces, permite ubicar a estas aves en distintas categorías de acuerdo a las modificaciones que producen. Esa información es usada como análoga en la interpretación del registro fósil. En muchas oportunidades, las rapaces ingieren solo parcialmente a su presa, dependiendo del tamaño y disponibilidad de la misma. En nidos y perchas es común encontrar egagrópilas y restos óseos ingeridos aislados y también porciones desechadas de las presas, huesos, piel y faneras que no han sido ingeridos. En muestras actuales, fácilmente se pueden identificar estos dos tipos de restos. Se presentan las evaluaciones tafonómicas de huesos de egagrópilas y restos de presa acumulados por varias aves rapaces. Se evaluaron para cada una, separadamente, los huesos incluidos en egagrópilas y los huesos de los restos no digeridos. En cada caso, el análisis mostró diferencias en la representación anatómica, en los patrones de rotura de los distintos elementos esqueléticos y en las evidencias de corrosión por digestión. Se observó que si ambas muestras se evalúan en conjunto, el depredador queda ubicado en una categoría de menor modificación con respecto a la que se lo ubica cuando se evalúan sólo los restos ingeridos. Tanto los huesos ingeridos como los de los sectores corporales desechados son potencialmente susceptibles a ser enterrados juntos. Si esta situación es extrapolada al registro fósil, es probable que ambos tipos de restos puedan aparecer mezclados. Este carácter de mezcla afecta los resultados y las interpretaciones pueden estar sesgadas por la presencia de restos no ingeridos. Este tipo de análisis es una vía alternativa que permite evaluar la complejidad de los mecanismos involucrados en el origen de acumulaciones de restos de microvertebrados, que puede ser tenido en cuenta al evaluar tafonómicamente una asociación fósil acumulada.Simposio IX: El presente es la clave del pasado: importancia de los estudios actualistas en paleontologíaFacultad de Ciencias Naturales y Muse
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Journal of South American Earth Sciences, 2022
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Papers in Palaeontology, 2021
We analyse the taxonomic status and diversity of the late Miocene Octodontoidea (Hystricognathi) ... more We analyse the taxonomic status and diversity of the late Miocene Octodontoidea (Hystricognathi) Cercomys primitiva and related samples, a taxon previously known only from the holotype specimen. New findings associated with an extensive review of late Miocene and early Pliocene rodents have allowed us to recognize the occurrence of this and other related species in several localities of central and western Argentina, and in south‐central Bolivia. We discuss the invalidity of Cercomys and propose the new genus Metacaremys, which includes the type species Metacaremys primitiva comb. nov. and two new species, Metacaremys calfucalel sp. nov. and Metacaremys dimi sp. nov. Osteological, brain and dental morphology show that the new genus is not related to Brazilian Echimyidae, as previously considered, but to the southern family Octodontidae. Although the molar morphology of this genus is quite conservative, comparison of the samples shows a variation in size. We discuss the plausible evolutionary pattern explaining this variation and the implied biochronological and biostratigraphical information. It is recognized as an anagenetic lineage in which an increase in size occurs from the oldest species, M. primitiva comb. nov. (early late Miocene, c. 9.23 Ma), to the youngest species, M. dimi sp. nov. (Miocene–Pliocene boundary, c. 5.28 Ma). Metacaremys calfucalel is intermediate in size and age between these two species. The polarity of this pattern of change is consistent with that shown by other partially synchronous independent lineages of octodontoids, thus providing new evidence for the biochronological and biostratigraphic scheme of the late Miocene and early Pliocene of southern South America.
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Historical Biology
Micro- and macromammal remains from Cerro La Bota (late Miocene; La Pampa Province, Argentina) ar... more Micro- and macromammal remains from Cerro La Bota (late Miocene; La Pampa Province, Argentina) are taphonomically analysed. All remains form a single sample recovered from Chasicoan sediments (facies FA2) of the Cerro Azul Formation, constituted by a lateral and vertical erosive superposition of sandstone and conglomeratic bodies, formed by episodic development of perennial streams without flow division on a loessic substrate. The analysis reveals that micro- and macromammal remains originally accumulated independently and differently. Once each type of accumulation was buried in a loessic context, the development of streams gave place to a reworking process of fossils that were finally incorporated together into the stream channel. Taphonomic characteristics of micromammals are interpreted as the result of the leftover prey accumulated by predators, probably at a den site. Instead, the macromammals respond to an attritional accumulation of individuals inhabiting the area. Even considering the reworking as an important process that affected this assemblage, the taxonomic and taphonomic evidences suggest a relatively short time for its formation. The different taphonomic histories of the remains evidence a complex association that differs from other assemblages from the Cerro Azul Formation previously analysed, and it is here assigned to the channel-lag taphonomic mode.
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A taphonomic analysis was made on small mammal remains recovered from fossil bone accumulations, ... more A taphonomic analysis was made on small mammal remains recovered from fossil bone accumulations, interpreted as whole and fragmented pellets from Upper Pleistocene levels of the Quequén Salado River cliffs (Buenos Aires, Argentina). Additionally, the probable source of the accumulation and some features associated with post-burial preservation processes are discussed. From the available information it is possible, through analyzing the anatomical representation of the remains and the degree of digestion, to show affinities with extant accumulations produced by nocturnal birds of prey. Nevertheless, breakage patterns are biased in this association as it shows much higher values than in recent analysis based on pellets of extant nocturnal raptors. Diagenetic bone fractures found in skeletal elements probably hidden the fractures produced at the moment of predation. Micro structural characteristics of remains conserved in pellets are indicative of good preservation indicating a rapid b...
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Ameghiniana, 1988
New remains assignable to species of Thylatheridiurn Reig, 1952, from Huayquerian (late Miocene) ... more New remains assignable to species of Thylatheridiurn Reig, 1952, from Huayquerian (late Miocene) sediments of La Pampa Province (Argentina) are described. Specimen MLP 86-Vll-I0-l, referred to T. dolgopolae, shows several unique features among members of this genus: p3 obliquely oriented in the dental row, talonid of m4 extremely narrow. Specimen PVM 1001 is assigned to a new species: T. hudsoni, characterized by its rather slender mandibular ramus, lacking a developed labial convexity, and intermediate in size from those of. T. pascuali and T. dolgopolae; ml-4 with poorly developed anterior cingula, and talonid of m4 comparatively very broad. The dental specializations found in all species of Thylatheridium suggest an adaptive tendence over small vertebrate predation, although it can 't be discarded partially insectivorous habits, at least at some stages of their ontogenetic development.
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The Holocene
Pseudoryzomys simplex (Winge 1887) is a small to medium sized terrestrial oryzomyine rodent (Cric... more Pseudoryzomys simplex (Winge 1887) is a small to medium sized terrestrial oryzomyine rodent (Cricetidae, Sigmodontinae) widely distributed in humid environments of tropical and subtropical lowlands of South America with a marked rainy season. The occurrence of this species in the south-central Pampean region between 4700 and 200 ka cal BP was originally associated with some warm climatic episodes. A later hypothesis points out that P. simplex was a typical element of the Humid Pampa subregion during this period, whose distribution was retracted to the north due to the strong anthropic modifications in the area. To corroborate these hypotheses, the niche of occurrence of P. simplex was calculated to analyse the preferred climatic conditions of contemporaneous and fossil record of the species since 4700 ka cal BP. The derived climatic niche of P. simplex shows a marked preference for areas with seasonality precipitation patterns and tropical/subtropical conditions. Geographical estima...
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Sediments assigned to the Vaca Mahuida Formation outcrop at Sierra El Fresco area, southeast from... more Sediments assigned to the Vaca Mahuida Formation outcrop at Sierra El Fresco area, southeast from Puelen, La Pampa Province. These sediments represent a depositional sequence in a depressed area, covered by a wide, fresh- to brackish- water lake. So far, only some ichnofossils, invertebrates (pelecypods and gastropods), and vertebrates (fish, anurans, birds and mammals), have been recorded. The mammal specimens described in this paper belong to the order Notoungulata, the most diverse of the South American native ungulates. Among the notoungulates, these specimens markedly resemble members of the family Oldfieldthomasiidae (Typotheria), which ranges from the Tiupampian (early Paleocene) to the Divisaderan ages (late Eocene?). Some features are interpreted as derived (e.g. lack of paraconid, paralophid connected to the anterolingual cingulum, entoconid poorly differentiated), possibly indicating that this taxon is somewhat more advanced than those of the Paleocene. The material from ...
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Spanish Journal of Palaeontology, 2021
Se dan a conocer nuevos registros de Dasypodidae (Xenarthra, Cingulata) para la Formación Cerro A... more Se dan a conocer nuevos registros de Dasypodidae (Xenarthra, Cingulata) para la Formación Cerro Azul en la provincia de La Pampa, Argentina. El material estudiado consiste en placas aisladas de la coraza dorsal y procede de las localidades: Laguna Chillhué, Cerro de los Guanacos, Bajo Giuliani, Quehue, Naicó, Laguna Guatrache, Telén, Loventué, Cerro de la Bota y Salinas Grandes de Hidalgo, comprendidas entre los 36°-38° S and 63°-67°0. Se reconocen Chasicotatus ameghinoi, Macrochorobates scalabrinii, Zaedyus pichiy, Vetelia perforata, Doellotatus inornatus, Doellotatus chapadmalensis, Proeuphractus, Macroeuphractus morenoi, Chorobates villosissimus, y Gen. nov. "A" Scillato Yane. Los siete primeros taxones y Gen. nov. "A" Scillato Yane son citados por vez primera para esta formación. Se constata la presencia de una probable nueva especie de Proeuphractus. La Formación Cerro Azul es referida al Huayqueriense (Miocene tardío) sobre la base de diferentes grupos de m...
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Global Journal of Archaeology & Anthropology, 2017
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Ameghiniana, 1988
Recently collected portions of the left and right mandibular rami of the extinct Palaeoctodon aff... more Recently collected portions of the left and right mandibular rami of the extinct Palaeoctodon aff. P. simplicidens are analyzed. These remains are from the Huayquerian (late Miocene) Cerro Azul Formation, that outcrops in Bajo Giuliani, La Pampa Province, Argentina. We concluded that the following features, among others, indicate that Palaeoctodon represents the oldest Ctenornyine-like Octodonudae: the major axis of the masticatory plane directed antero-posteriorly, and a very reduced third molar.
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Historical Biology
Among extinct sloths, Nothrotheriidae nothrotheriines are characterised by caniniforms (when pres... more Among extinct sloths, Nothrotheriidae nothrotheriines are characterised by caniniforms (when present) separated by a diastema from the molariform tooth row and quadrangular, rectangular or trapezoidal molariforms with longitudinal grooves on the lingual and labial surfaces. The subfamily Nothrotheriinae is recorded from the Middle Miocene of Bolivia and Argentina to the Pleistocene of different regions of South America, Central America and North America. Neogene well-known representatives include Pronothrotherium, Huilabradys, Mionothropus, Aymaratherium, Lakukullus and the recently defined genus Mcdonaldocnus, whose remains were found from Argentina, Colombia, Uruguay, Peru, Brazil and Bolivia. Mcdonaldocnus includes materials from Argentina and Bolivia previously assigned as 'Xyophorus'. New records from Late Miocene levels of the Cerro Azul Formation cropping out in the Chasicó creek locality, Buenos Aires Province, and in the localities of Telén and Loventué, La Pampa Province, allow us to describe cranio-dental remains of Nothrotheriinae Mcdonaldocnus bondesioi and Mcdonaldocnus sp., respectively. The identification of Mcdonaldocnus sp. in the Cerro Azul Formation at La Pampa Province constitutes the first record of Nothrotheriinae for this province.
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Quaternary, 2022
Experiments based on the premise of uniformitarism are an effective tool to establish patterns of... more Experiments based on the premise of uniformitarism are an effective tool to establish patterns of taphonomic processes acting either before, or after, burial. One process that has been extensively investigated experimentally is the impact of trampling to large mammal bones. Since trampling marks caused by sedimentary friction strongly mimic cut marks made by humans using stone tools during butchery, distinguishing the origin of such modifications is especially relevant to the study of human evolution. In contrast, damage resulting from trampling on small mammal fossil bones has received less attention, despite the fact that it may solve interesting problems relating to site formation processes. While it has been observed that the impact of compression depends on the type of substrate and dryness of the skeletal elements, the fragility of small mammal bones may imply that they will break as a response to compression. Here, we have undertaken a controlled experiment using material res...
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Supplemental materials are available for this article for free at www.tandfonline.com/UJVP Citati... more Supplemental materials are available for this article for free at www.tandfonline.com/UJVP Citation for this article: Nicoli, L., R. L. Tomassini, and C. I. Montalvo. 2017. The oldest record of <i>Ceratophrys</i> (Anura, Ceratophryidae) from the Late Miocene of central Argentina. Journal of Vertebrate Paleontology. DOI: 10.1080/02724634.2017.1261360.
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Papers by Claudia Montalvo