Nueva evidencia sobre la relación filogenética entre los osos pleistocenos de América del Sur y del Norte

Fil: Soibelzon, Leopoldo Héctor. División Paleontología Vertebrados. Facultad de Ciencias Naturales y Museo. Universidad Nacional de La Plata; Argentin

Aurora do Tocantins, Brasil : viaje de campaña

Fil: Soibelzon, Leopoldo Héctor. División Paleontología Vertebrados. Facultad de Ciencias Naturales y Museo. Universidad Nacional de La Plata; ArgentinaFil: Avilla, Leonardo. Universidade Federal do Estado do Rio de Janeiro; Brazi

Chaetophractus vellerosus (Mammalia: Dasypodidae) in the Ensenadan (Early - Middle Pleistocene) of the southeastern Pampean region (Argentina) : Paleozoogeographical and paleoclimatic aspects

The xenarthran fauna recognized for the Ensenadan age is particularly abundant; Dasypodidae comprise approximately 20 % ofthis fauna. Chaetophractus vellerosus is recorded in the Pampean region from the Bonaerian-Lujanian (Middle Pleistocene - Late Pleistocene/Early Holocene) to the present, with a current disjunct distribution (a continuous main area comprising the Gran Chaco and central Argentina, and a secondary area in the coastal region of Buenos Aires Province) attributed to a wider paleodistribution. The material s presented here are from Ensenadan sediments outcropping at Punta Hennengo (General Alvarado County, Buenos Aires Province), that would have been deposited under arid to semiarid climate conditions. These allow extension of the temporal distribution of the species to the Ensenadan in the Pampean region, as well as representing new evidence to test hypotheses of distributional changes related to global climatic variations recognized foy the Quatemary. In this sense, the current disjunct distribution can be interpreted as the result of fundamentally humid recent conditions that resulted in a relict occurrence of the species in coastal areas.Museo de La Plat

Review of the aquatic and continental carnivores (Mammalia, carnivora) from the Miocene of the Argentine Mesopotamia

Desde mediados del siglo XIX cuando comenzaron los primeros hallazgos de vertebrados fósiles en los sedimentos del Mioceno (Formaciones Paraná e Ituzaingó) de las barrancas del río Paraná, en la provincia de Entre Ríos, se registraron diversos materiales pertenecientes a Carnivora de las familias Procyonidae, Ursidae y Phocidae. Los primeros Procyonidae que fueron descriptos por Ameghino (1885) y Burmeister (1891) actualmente se refieren a la especie Cyonasua argentina, y están entre los más antiguos registros para América del Sur. También en 1885, F. Ameghino describió una nueva especie de Ursidae, Arctotherium vetustum, a la que supuso procedente de la Formación Ituzaingó. En cuanto a los carnívoros acuáticos, Gervais y Ameghino (1880) dieron a conocer un supuesto Otariidae, procedente del “Patagónico” de las barrancas del Paraná (Fm. Paraná o Ituzaingó) identificado como Arctophoca fischeri. Posteriormente, Florentino Ameghino (1893, 1897) describió el pinípedo Properiptychus argentinus. El material tipo de P. argentinus y otros restos fueron reestudiados por Muizon y Bond (1982), quienes lo reinterpretaron como un Phocidae Monachinae. Nuevo material aquí descripto reafirma las particularidades de esta especie, cuya relación con los Monachinae (e.g. Monachus) y su probable ancestralidad en la radiación de las focas antárticas no han sido puestas en duda. También se menciona un nuevo registro de Phocidae para el arroyo Ensenada, en Entre Ríos, aunque su procedencia estratigráfica no es muy clara.Since the mid-XIX century when the first fossil vertebrates were found in the Miocene sediments (Paraná and Ituzaingó Formations) exposed along the Paraná cliffs, in Entre Ríos Province, there various remains belonging to Carnivora (Procyonidae, Ursidae, and Phocidae) were collected. The first remains of Procyonidae were described by Ameghino (1885) and Burmeister (1891), and belong to the species Cyonasua argentina, being this record amongst the earliest in South America. Also in 1885, F. Ameghino described a new species of Ursidae, Arctotherium vetustum, supposedly coming from the Ituzaingó Formation. Taking into account the aquatic carnivores, Gervais and Ameghino (1880) described a supposed Otariidae identified as Arctophoca fischeri from the “Patagonian” along the Paraná cliffs (Paraná or Ituzaingó Formation). Later Florentino Ameghino (1893, 1897) described the pinnipedian Properiptychus argentinus. The type material of P. argentinus and other materials referred to the same species were reviewed by Muizon and Bond (1982) who concluded that it belonged to Monachinae Phocidae. New material here described confirms the peculiarities of this species, whose relationship with the Monachinae (e.g., Monachus) and its ancestrality within the radiation of the Antarctic seals have not been questioned. Also mentioned is a new record of a Phocidae from the Ensenada Creek (Entre Ríos), although its stratigraphic provenance is not very clear.Fil: Soibelzon, Leopoldo Héctor. Universidad Nacional de la Plata. Facultad de Ciencias Naturales y Museo. División Paleontología Vertebrados; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Bond, Mariano. Universidad Nacional de la Plata. Facultad de Ciencias Naturales y Museo. División Paleontología Vertebrados; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentin

Inferring palaeoecology in extinct tremarctine bears (Carnivora, Ursidae) using geometric morphometrics

In this study we explore the ecomorphological patterns of extinct tremarctine bears in South America during the Great American Biotic Interchange (GABI). These patterns are used to derive palaeoautoecological inferences in extinct tremarctines and their palaeosinecological relationships within Plio-Pleistocene ecosystems. We used geometric morphometrics of landmark data to recover the shape of the craniomandibular skeleton of bears. The results reveal different ecomorphological specializations in extinct tremarctines during the Plio-Pleistocene of South America. Indeed, these bears could have increased the percentage of plant matter in their diets according with the increased diversity of large carnivores in South America after the GABI. Omnivorous bears retain the ability to behave as carnivores or herbivores depending on resource availability. This fact strongly supports that bears are one of the most ecologically and morphologically adaptable members of the large carnivore guild. Moreover, their skull morphology could reflect ecological adaptations under different selection pressures with the required evolutionary timeMuseo de La Plat

Accessory protection structures in <i>Glyptodon</i> Owen (Xenarthra, Cingulata, Glyptodontidae)

The Glyptodontidae (Mammalia, Xenarthra) are one of the most common paleofaunistic elements in the South American megafauna. In this context, of the six genera most frequently recorded in the South American Pleistocene (Glyptodon, Neosclerocalyptus, Hoplophorus, Neuryurus, Panochthus and Doedicurus), at least four (Hoplophorus, Neuryurus, Panochthus and Doedicurus) present structures in their caudal armor that could have had defensive/offensive functions, in addition to a solid dorsal carapace and cephalic shield. In this article, we provide the first record and description of a series of highly modified osteoderms, located at the anterolateral region and over the cephalic notch of the dorsal carapace. These "spine"-like osteoderms were found in two of the largest Pleistocene glyptodonts: Glyptodon munizi (early-middle Pleistocene) and, G. reticulatus (late Pleistocene-early Holocene). We propose that they are structures for protection of the neck and abdomen, the most vulnerable body regions of these large armored animals, since they are not covered by the cephalic shield, carapace or caudal armor. Noteworthy, structures like those described herein are not known in glyptodonts recorded before the Great American Biotic Interchange (GABI), so it could be a reaction to the arrival of Smilodon and Arctotherium (Carnivora, Mammalia) the largest terrestrial carnivores that ever lived in South America.Facultad de Ciencias Naturales y Muse

Morfología de los dientes deciduos de algunos tremactinos (Ursida: Tremarctinae)

Se describe y compara la morfología de algunos dientes deciduos de Arctotherium tarijense Ameghino and A. angustidens Gervais and Ameghino (Ursidae, Tremarctinae) por primera vez. La morfología del dP4 y dp4 es muy similar a la del M1 y m1. La morfología general de los dP/dp4 en A. tarijense y Ursinae es similar, aunque la morfología de sus dientes definitivos es muy diferente. Los dP/dp4 de A. tarijense parecen poseer un conjunto de caracteres generalizados (en relación con el contorno de la corona, el protocono y el parastilo del dP4, el metacónido y el hipocónido del dp4). Desgraciadamente no es posible comparar esas piezas con sus homólogas en otros tremarctinos, por lo que no es posible incluir estos caracteres en el análisis filogenético de la subfamilia Tremarctinae con el fin de saber si sus relaciones filogenéticas se ven afectadas o no. Es importante remarcar que si esos carcateres estuviesen presentes en los M/m1 de A. tarijense, al menos algunos de ellos podrían ser interpretados como plesiomorfías. En este sentido, ¿la morfología de los dientes deciduos es más conservadora que la de los definitivos?.The morphology of some deciduous teeth of Arctotherium tarijense Ameghino and A. angustidens Gervais and Ameghino (Ursidae: Tremarctinae) is here described and compared for the first time. The crown morphology of dP4 and dp4 is similar to that of M1 and m1. The general morphology of dP/dp4 in A. tarijense and Ursinae is similar, but their permanent dentition morphology is different. The dP/dp4 of A. tarijense seem to bear a generalized set of characters (i.e. crown outline, the protocone and parastyle of dP4, the metaconid and hypoconid of dp4); unfortunately these teeth cannot be compared with their homologues in other tremarctines. Consequently, we are unable to include these characters in the phylogenetic analysis of the Tremarctinae subfamily in order to know whether the phylogenetic relationships are affected or not. It is interesting to note, that had these characters been present in M/m1 of A. tarijense, at least, some of them could be undoubtedly regarded as plesiomorphic features. In this respect, is the deciduous teeth morphology more conservative than that of permanent teeth?.Museo de La Plat

Chaetophractus vellerosus (Cingulata: Dasypodidae)

Chaetophractus vellerosus (Gray, 1865) is commonly called Piche llorón or screaming hairy armadillo. Chaetophractus has 3 living species: C. nationi, C. vellerosus, and C. villosus of Neotropical distribution in the Bolivian, Paraguayan, and Argentinean Chaco and the southeastern portion of Buenos Aires Province. C. vellerosus prefers xeric areas, in high and low latitudes, with sandy soils, but is able to exist in areas that receive more than twice the annual rainfall found in the main part of its distribution. It is common in rangeland pasture and agricultural areas. C. vellerosus is currently listed as "Least Concern" by the International Union for Conservation of Nature and Natural Resources and is hunted for its meat and persecuted as an agricultural pest; however, the supposed damage to agricultural-farming lands could be less than the beneficial effects of its predation on certain species of damaging insects.Facultad de Ciencias Naturales y Muse

Los carnívoros (Carnivora, Mammalia) terrestres del Cuaternario de América del Sur

El registro fósil de los carnívoros placentarios continentales de América del Sur abarca el Mioceno tardío-reciente y se inicia con el ingreso de las familias Felidae, Canidae, Ursidae, Mustelidae y Procyonidae desde América del Norte. Este evento, conocido como "Gran Intercambio Biótico Americano", se encuentra estrechamente asociado al levantamiento del istmo de Panamá. En este capítulo se recopilan los últimos avances en la Sistemática, Filogenia, Bioestratigrafia, Biogeografia y Paleoecología de los carnívoros continentales de América del Sur. Los primeros registros corresponden a los prociónidos del "grupo" Cyonasua del Mioceno tardío (Huayqueriense). A finales del Plioceno (Vorohuense) ingresan los cánidos (Caninae) y los mustélidos (Mustelinae), pero es recién a comienzos del Ensenadense (Plioceno tardío-Pleistoceno medio) cuando se diversifica el grupo con la aparición en escena de los Ursidae, Felidae, Mephitinae, Lutrinae y los grandes cánidos. La diversidad de Carnívoros fósiles y vivientes en América del Sur puede verse como el resultado de la inmigración independiente de varios linajes dentro de cada subfamilia (o géneros), así como la radiación adaptativa de estos inmigrantes que originaron varias especies y géneros endémicos.The terrestrial placentary carnivorous (Mammalia, Carnivora) of South America are recorded in the late Miocene (Huayquerianj-recent, with representatives of the families Felidae, Canidae, Ursidae, Mustelidae and Procyonidae. These records are closely associated to the rising of the Isthmus of Panama, well known as biogeographic "Great American Biotic Exchange" event. In this chapter we update the last advances in the systematic, phylogeny, bioestratigraphy, Biogeography and Paleoecology of the continental carnivores of America of the South. The first occurrence corresponds to the procyonids of the Cyonasua "group", dated as late Miocene (Huayquerian). At the end of the Pliocene (Vorohueian) canids (Caninae) and rnustelids (Mustelinae) appear, but it is at the beginning of the Ensenadan (late Pliocene - middle Pleistocene) when the group diversified, represented by the first record of Ursidae, Felidae, Mephitinae, Lutrinae and large canids. The diversity of fossil and recent carnivores could be a consequence of several independent immigrations (also within subfamilies and genera), and the adaptative radiation of these immigrants in South America