Search

In this work, we present several new materials collected at the pink sandstone levels from the Las Flores Formation at the Cerro Pan de Azúcar (Gaiman, Chubut Province, Argentina) and compare them with taxa present in other localities of similar age. The Metatheria taxa described here are 1) the 'Ameridelphia' Sternbergiidae indet; 2) the Didelphimorphia Protodidelphis cf. mastodontoides and Guggenheimia glykeia sp. nov. (Protodidelphidae); 3) the Polydolopimorphia Pliodolops rothi and Pliodolops cf. kamektsen (Polydolopidae); and 4) the Microbiotheria Eomicrobiotherium diluculum sp. nov. (Microbiotheriidae). On the other hand, the Cingulata Dasypodidae is represented by the Astegotheriini Prostegotherium astrifer. This fauna shares more species with those occurring in the localities from Paso del Sapo than with any other early – middle Eocene localities. However, at the generic level, it shares several taxa with the Itaboraian fauna from Sao José de Itaboraí. Finally, the faunal associations from Pan de Azúcar, Paso del Sapo, Cañadón Hondo, and Bajo de la Palangana could be, at least in part, synchronous, representing locally the Riochican SALMA, with an age spanning from 51 to 45 Ma (early Ypresian- early Lutetian). [ABSTRACT FROM AUTHOR]

The discovery of new primates from the ?Late Eocene epoch of Amazonian Peru extends the fossil record of primates in South America back approximately 10 million years. Primate diversification in South America The New World monkeys (or platyrrhines) of South America form a distinctive group whose origins are a mystery. The earliest known remains are 26 million years old and from Bolivia, and shed little light on the question. New remains from the Eocene of Amazonian Peru put the record back ten million years, and bear more resemblance to extinct African primates than to extant or fossil platyrrhines, suggesting a close relationship with African taxa. The fossils also bring the first appearances of monkeys and caviomorph rodents (guinea pigs and allies) in South America closer together, raising yet more questions about the origins of these distinctive South American groups. The platyrrhine primates, or New World monkeys, are immigrant mammals whose fossil record comes from Tertiary and Quaternary sediments of South America and the Caribbean Greater Antilles.sup.1,2. The time and place of platyrrhine origins are some of the most controversial issues in primate palaeontology, although an African Palaeogene ancestry has been presumed by most primatologists.sup.3,4. Until now, the oldest fossil records of New World monkeys have come from Salla, Bolivia.sup.5,6, and date to approximately 26 million years ago.sup.7, or the Late Oligocene epoch. Here we report the discovery of new primates from the ?Late Eocene epoch of Amazonian Peru, which extends the fossil record of primates in South America back approximately 10 million years. The new specimens are important for understanding the origin and early evolution of modern platyrrhine primates because they bear little resemblance to any extinct or living South American primate, but they do bear striking resemblances to Eocene African anthropoids, and our phylogenetic analysis suggests a relationship with African taxa. The discovery of these new primates brings the first appearance datum of caviomorph rodents and primates in South America back into close correspondence, but raises new questions about the timing and means of arrival of these two mammalian groups., Author(s): Mariano Bond [sup.1] , Marcelo F. Tejedor [sup.2] [sup.3] , Kenneth E. Campbell Jr [sup.4] , Laura Chornogubsky [sup.5] [sup.6] , Nelson Novo [sup.2] , Francisco Goin [sup.1] Author [...]

Author(s): Mariano Bond; Marcelo F. Tejedor; Kenneth E. Campbell, Jr; Laura Chornogubsky; Nelson Novo; Francisco Goin Nature 520, 538-541 (2015); doi:10.1038/nature14120 In Extended Data Fig. 1 of this Letter, the [...]

Polydolopidae is a family of Palaeogene marsupials recorded from outcrops in southern South America and the Antarctic Peninsula. They are mostly represented by skull fragments or maxillary, dentary and molar remains. A taxonomic and systematic revision is carried out with the inclusion of a phylogenetic analysis encompassing almost every polydolopid species and five marsupial species found to be related to them in previous analyses (Bonapartherium hinakusijum , Epidolops ameghinoi , Microbiotherium tehuelchum , Prepidolops didelphoides and Roberthoffstetteria nationalgeographica). The Polydolopidae was recovered as a monophyletic group, even though no resolution about its sister-group can be found. The following genera are recovered: Antarctodolops , Amphidolops , Archaeodolops , Eudolops , Hypodolops gen. nov. , Kramadolops , Pliodolops , Pseudolops and two unidentified genera (Gen. et sp. indet 1 and 2). One genus and three new species are recognized. The family appeared at the beginning of the Palaeocene and disappeared during the Early Oligocene. The extinction of the group could be related to climatic deterioration in the Early Oligocene, when temperature and the humidity dropped, provoking desertification in the region where Polydolopids evolved. [ABSTRACT FROM AUTHOR]

In the last few years, the Quebrada de Los Colorados Formation has become an important middle Eocene fossiliferous unit in Northwestern Argentina. In this unit, the South American native ungulates were until now only represented by the order Notoungulata, including one family of Typotheria and three of Toxodontia. In this contribution, we present a new faunistic assemblage of South American native ungulates, collected from outcrops of the Quebrada de Los Colorados Formation at Los Cardones National Park, Calchaquí Valleys, Salta Province (Argentina). This new assemblage is constituted by the following taxa: litoptern Didolodontidae cf. Ernestokokenia sp., Astrapotheria indet., and notoungulate Notostylopidae Homalostylops sp., a Homalostylops sp., typothere "Oldfieldthomasiidae" Colbertia falui sp. nov., Colbertia lumbrerense, and Colbertia sp. and toxodont "Notohippidae" Pampahippus secundus. Colbertia falui sp. nov. differs from the other species of Colbertia by the following features: lower cheek teeth with both more labially angular and oblique trigonid; lower premolars more labio-lingually compressed; with proportionally larger trigonid, and shorter talonid; ectoflexid transversally deeper; lower molars with a more developed paralophid, and more expanded metalophid and entoconid; the latter is located in a more mesial position, being closer to the metaconid; deep and lingually narrower talonid basin; disto-lingual sulcus transversally shallower; more developed cingulids; and m3 with less lingually projected hypoconulid. This new fauna markedly increases the taxonomic richness known for this formation since it includes the first mention of notostylopids, "oldfieldthomasiids", litoptern didolodontids, and astrapotheres. With the current evidence, we postulate an ungulate migration from Patagonia to Northwestern Argentina during the Eocene. We also hypothesize that the observed taxonomic differences among the Quebrada de Los Colorados, Geste, and Lumbrera formations are more probably associated to orogenic factors that have regulated the faunal dynamic in Northwestern Argentina during the Paleogene than to a differential sampling effort or taphonomic biases. [ABSTRACT FROM AUTHOR]

The Quebrada de Los Colorados Formation (Los Cardones National Park, Salta Province, north-western Argentina), is an Eocene--Oligocene unit well represented in the Calchaquí Valley area. Here we describe a new metatherian association recorded from the base of this formation, inferred as middle Eocene. Represented taxa are: Sparassodonta, family indet.: Patene simpsoni; Polydolopimorphia, Bonapartheriiformes, Argyrolagoidea: family, genus, and species indet.; and Bonapartherioidea, Prepidolopidae: Punadolops alonsoi and Coloradolops cardonensis gen. et sp. nov. Patene simpsoni is also found in the Tonco Valley, near Los Cardones, and at São José de Itaboraí, Rio de Janeiro, Brazil. Punadolops alonsoi was originally described from the Geste Formation in Salta and Catamarca provinces. Hitherto, no other Argyrolagoidea have been found in north-western Argentina in the Palaeogene. Coloradolops cardonensis is unique to the locality and levels here described. The preservation of part of the skull constitutes the best prepidolopid remains known. North-western Argentina is a key region for the study of the evolution of South American mammals, since it has a singular geographical location between the Neotropics and the southernmost part of South America. Due to biogeographical constraints, it may lead to a better comprehension of the continental distribution of metatherian lineages during Cenozoic times. [ABSTRACT FROM AUTHOR]