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High latitude metatherians from the Middle Miocene of Patagonia (Argentina and Chile) are only known from medium-sized Sparassodonta, and undescribed taxa collected in several fossil localities of Collon Cura (Argentina) and Río Frías (Chile) Formations, although the latter has several species reported and mostly recognised for the slightly older Santa Cruz Formation. In this contribution we describe five new genera and six new species of metatherians from Collon Cura Formation at Cerro Zeballos, Chubut province (Argentina), based on 11 specimens that notably increased the diversity of Collon Cura Formation. The specimens were assigned to the orders Paucituberculata (Palaeothentoidea), Sparassodonta (Hathliacynidae), and Polydolopimorphia (Argyrolagidae), and are taxa of small size, including the smallest palaeothentoids known to date. Also, the Palaeothentoidea of Cerro Zeballos are amongst the youngest of the superfamily in Patagonia. The new specimens described herein show morphological differences with other metatherian associations already known, probably related to adaptive changes coincident with the Middle Miocene Climatic Transition and the beginning of a faunal turnover. [ABSTRACT FROM AUTHOR]

We present a systematic review of the extinct species included in the family Caenolestidae, one of the few South American metatherian groups that has survived to the present. We perform a cladistic analysis based on a data matrix consisting of all extant and extinct species that have been referred to this family, 100 morphological characters and two sets of molecular data (cytochrome b and cytochrome c oxidase I). Morphological and molecular data were analysed separately and in combination, under maximum parsimony and maximum likelihood methods. As a result, caenolestids are recovered as a monophyletic group within which we formally recognize three new taxa: Caenolestoides miocaenicus gen. & sp. nov. Gaimanlestes pascuali gen. & sp. nov. and Stilotherium parvum sp. nov. from the Early Miocene of Patagonia, Argentina. Stilotherium is the earliest diverging lineage of caenolestids followed by Gaimanlestes , while C. miocaenicus was recovered as the extinct species most closely related to extant caenolestids. [ABSTRACT FROM AUTHOR]

The article presents a study on geographic and potential distribution of the poorly known South American bat Histiotus macrotus (Chiroptera: Vespertilionidae). The findings include localities assigned to H. macrotus belonging to a taxonomic complex distributed in two contrasting areas, the two areas being Bolivia and North West Argentina and central Chile and South West Argentina, and the two forms supposed to be sister species or may not have an immediate common ancestor within genus.

The Patagonian weasel (Lyncodon patagonicus) is one of the least known carnivores from South America, and excluding some contributions, knowledge of it seems anecdotal. It is supposed to inhabit herbaceous and arid environments of Argentina and Chile. Here we assess the potential distribution of the Patagonian weasel both during the present and the Last Glacial Maximum (LGM). We also integrate some of this information, providing a historical and geographic analysis (both through ecological niche modeling and biogeographic schemes) of the distribution of L. patagonicus. We found 2 major core areas of distribution, 1 in northwestern Argentina and another in southern Argentina (i.e., Patagonia). Patagonian weasel distribution seems to be primarily related to cold areas with marked temperature seasonality and elevations below 2,000 m above sea level. From LGM to the present, we observed a major retraction in potential distribution areas that might indicate the existence of a vicariance process affecting Patagonian weasel distribution. [ABSTRACT FROM AUTHOR]

The article discusses the results of a study on the distribution of bat species, Histiotus magellanicus, in Patagonia, Argentina. The study revealed the presence of bat species in the provinces of Chubut and Rio Negro and mentioned the restriction of the species as endemic to the Subantarctic Forests. It provided information on Patagonian bat species through cradiodental measurements. The study also highlighted Patagonian bat specimens and localities for Tadarida brasiliensis, Histiotus macrotus, Myotis chiloensis and Lasiurus varius for Chubut province.

Occurrence records represent the key to understanding species distribution patterns. I analyzed the historical and geographical occurrence of Dromiciops gliroides, a marsupial endemic to the temperate rain forests of southern Chile and Argentina and the sole living representative of the order Microbiotheria. Eighty-eight localities spanning 7°31′ latitude (~850 km) and 3°13′ longitude (~350 km) are known for the species and were taken from previous works and museum specimens and integrated in a geographic information system. Species distribution was analyzed in a historical, geographic, and biogeographic context, with the use of maps at different scales (region, subregion, province, ecoregion, and forest type). The software MaxEnt was used to generate 2 potential distribution models with environmental data. Generated models show a northern contraction and southern expansion in the species' potential distribution, with variation in habitat suitability throughout the current species range. Precipitation and some temperature-related variables influenced both generated models. The species' occurrence lies within the Andean region; Subantarctic and Patagonia subregions; and Maule, Valdivian, and Subandean Patagonia provinces. At a smaller scale, most of the localities occur within the Valdivian Temperate Forests ecoregion, and in the majority of the forest types described for it, implying broader ecological requirements than expected. Identification of critical areas through potential distribution modeling may have implications on species conservation and biogeographic patterns. [ABSTRACT FROM AUTHOR]

The article presents a study on the identity of Thylamys' specimens living in ecological regions in Pampas, Argentina. It mentions that Thylamys, which includes Marsupialia and Didelphidae, is the most varied of all the small didelphids. However, it states that its taxonomic situation remains unknown. It notes that many specimens of the genus' remains were compared where it provided evidence for the identification of T. fenestrae (Marelli) as a valid species. It adds that a neotype is assigned and a differential diagnosis is offered for the species.

The Patagonian opossum, Lestodelphys halli, is known from a few skeletons of captured animals and several isolated fragments recovered from owl pellets in Argentina. Recently, more than 300 remains (mandibles, maxillae, crania, and other bones) were found in owl pellets and associated bones, comprising the largest known collection of L. halli. A detailed morphological analysis of craniomandibular and dental variation is reported and comparisons with other small didelphids also are made. Intraspecific variation is discussed and differential diagnosis of the species is presented. [ABSTRACT FROM AUTHOR]

Polythelia is defined as the presence of supernumerary nipples without the presence of additional mammary gland, within the milk line extending from the axilla to the pubic region. Though the presence of dental anomalies can create a simple esthetic problem with specific clinical considerations, the association with familial polythelia has rarely been reported. A report of association of dental anomalies and polythelia in an Argentinean family is presented and the considerations about the dental practice suggesting a careful anamnesis and referral to a medical consultation with regard to possible pathologic conditions or potentially malignant transformation of accessory breasts are discussed. [ABSTRACT FROM AUTHOR]

Ten new records for the Chilean tree mouse, Irenomys tarsalis, are presented from western Argentina. This represents a near 30 % increase in the number of known localities for the species in this country. Nine of them fill a gap of at least 125 km in western Chubut Province, where I. tarsalis was previously known for only three records. Additionally, environmental information at an ecoregional and habitat scale is provided. [ABSTRACT FROM AUTHOR]

The small mammal fauna from northwestern Chubut Province (Argentina) is poorly known. We herein report small mammal assemblages from three new localities: Sierras de Tecka, an extra-Andean system elevated 900 m.a.sl.; Estancia La Mimosa on the Tecka river valley (at ca. 650 m.a.sl.); and Arroyo Pescado (at ca. 620 m.a.sl.) 40 km north of the other sites. Specimens were recovered from disaggregated owl pellets. Total species richness includes 16 native (13 sigmodontine and two caviomorph rodents, and one marsupial) and one introduced species. Estancia La Mimosa had the highest richness (n = 14), while Arroyo Pescado the lowest (n = 11). Four species were only recorded at Estancia La Mimosa (Akodon iniscatus, Calomys musculinus, Oligoryzomys longicaudatus and Mus musculus), two in Sierras de Tecka (Notiomys edwardsii and Microcavia australis) and one in Arroyo Pescado (Geoxus valdivianus). This work also adds new localities for Akodon iniscatus, Geoxus valdivianus, Lestodelphys halli and Notiomys edwardsii in western Chubut Province. [ABSTRACT FROM AUTHOR]

Taphonomy, a concept recognized in paleontology and anthropology, allows the estimation of time and circumstances of death by studying post-mortem conditions and factors related to the survival of bone remains. Among the different taphonomic variables, Binford (1981) proposed a categorization of bite marks, now recognized as standard for these studies. However, its original design in English could lead to misinterpretations or erroneous reports for not having a validated translation. A scoping review was conducted for articles in Spanish, without a time limit, that cited Binford ("Bones: Ancient Men and Modern Myths") in Google Scholar. Those who mentioned this methodology to categorize bite marks as taphonomic agent were included. Theses, books, posters and conference proceedings were excluded. We identified 349 documents, and 83 were selected according to criteria. 65.12 % referred only to animal bite marks without specifying categories; 26.51 % showed free translations or partial categorizations, and 8.43 % made categorizations without translation. The largest number of citations were made by authors from Argentina and Spain (54.22 % and 24.10 % respectively, as the only affiliation). The categories with the most free translations were "pitting" and "puncture" (11 and 8 different terms respectively). While Binford's categorization is widely cited in Spanish-speaking countries to define animal bite marks in bone, the absence of transculturation implies a lack of consensus for the scientific community. Beyond a literal translation, the adaptation and standardization of these terms is necessary to validate this methodology. [ABSTRACT FROM AUTHOR]

The Patagonian opossum (Lestodelphys halli), the southernmost living marsupial, inhabits dry and open environments, mainly in the Patagonian steppe (between ~32 °S and ~49 °S). Its rich fossil record shows its occurrence further north in Central Argentina during the Quaternary. The paleoenvironmental meaning of the past distribution of L. halli has been mostly addressed in a subjective framework without an explicit connection with the climatic "space" currently occupied by this animal. Here, we assessed the potential distribution of this species and the changes occurred in its geographic range during late Pleistocene-Holocene times and linked the results obtained with conservation issues. To this end, we generated three potential distribution models with fossil records and three with current ones, using MaxEnt software. These models showed a decrease in the suitable habitat conditions for the species, highlighting a range shift from Central-Eastern to South-Western Argentina. Our results support that the presence of L. halli in the Pampean region during the Pleistocene-Holocene can be related to precipitation and temperature variables and that its current presence in Patagonia is more related to temperature and dominant soils. The models obtained suggest that the species has been experiencing a reduction in its geographic range since the middle Holocene, a process that is in accordance with a general increase in moisture and temperature in Central Argentina. Considering the findings of our work and the future scenario of global warming projected for Patagonia, we might expect a harsh impact on the distribution range of this opossum in the near future.