The southern Mendoza province, located in the northern region of Patagonia, was inhabited by hunter-gatherer groups until historic times. Previous archaeological studies have reported canid remains among faunal assemblages, which were assumed to be part of the human diet. However, the taxonomic identification and significance of these canids within human groups have raised questions.
View Article and Find Full Text PDFSparassodonts were the apex mammalian predators of South America throughout most of the Cenozoic, diversifying into a wide array of niches including fox-like and even saber-toothed forms. Their extinction is still controversial, with different authors suggesting competition with other predators (placental carnivorans, terror birds, and carnivorous opossums), extinction of prey, and climate change as causal explanations. Here, we analyse these hypotheses using a novel approach implicating Bayesian analyses.
View Article and Find Full Text PDFThe vertebrate fossil record of the Pampean Region of Argentina occupies an important place in South American vertebrate paleontology. An abundance of localities has long been the main basis for constructing the chronostratigraphical/geochronological scale for the late Neogene-Quaternary of South America, as well as for understanding major patterns of vertebrate evolution, including the Great American Biotic Interchange. However, few independently-derived dates are available for constraining this record.
View Article and Find Full Text PDFThe Great American Biotic Interchange is considered to be a punctuated process, primarily occurring during four major pulses that began approximately 2.5 Ma. Central America and southeastern Mexico have a poor fossil record of this dynamic faunal history due to tropical climates.
View Article and Find Full Text PDFThe causes of Late Pleistocene megafaunal extinctions (60,000 to 11,650 years ago, hereafter 60 to 11.65 ka) remain contentious, with major phases coinciding with both human arrival and climate change around the world. The Americas provide a unique opportunity to disentangle these factors as human colonization took place over a narrow time frame (~15 to 14.
View Article and Find Full Text PDFAlthough the use of landmark data to study shape changes along a phylogenetic tree has become a common practice in evolutionary studies, the role of this sort of data for the inference of phylogenetic relationships remains under debate. Theoretical issues aside, the very existence of historical information in landmark data has been challenged, since phylogenetic analyses have often shown little congruence with alternative sources of evidence. However, most analyses conducted in the past were based upon a single landmark configuration, leaving it unsettled whether the incorporation of multiple configurations may improve the rather poor performance of this data source in most previous phylogenetic analyses.
View Article and Find Full Text PDFWe assessed the influence of a variety of aspects of locomotion and ecology including gait and locomotor types, maximal running speed, home range, and body size on postcranial shape variation in small to medium-sized mammals, employing geometric morphometric analysis and phylogenetic comparative methods. The four views analyzed, i.e.
View Article and Find Full Text PDFThe origins of the extinct Falkland Islands wolf (FIW), Dusicyon australis, have remained a mystery since it was first recorded by Europeans in the seventeenth century. It is the only terrestrial mammal on the Falkland Islands (also known as the Malvinas Islands), which lie ~460 km from Argentina, leading to suggestions of either human-mediated transport or overwater dispersal. Previous studies used ancient DNA from museum specimens to suggest that the FIW diverged from its closest living relative, the South American maned wolf (Chrysocyon brachyurus) around 7 Ma, and colonized the islands ~330 ka by unknown means.
View Article and Find Full Text PDFWe analyzed a concatenated (8492 bp) nuclear-mitochondrial DNA data set from 44 musteloids (including the first genetic data for Lyncodon patagonicus) with parsimony, maximum likelihood, and Bayesian methods of phylogenetic and biogeographic inference and two Bayesian methods of chronological inference. Here we show that Musteloidea emerged approximately 32.4-30.
View Article and Find Full Text PDFSouth America currently possesses a high diversity of canids, comprising mainly small to medium-sized omnivorous species, but in the Pleistocene there were large hypercarnivorous taxa that were assigned to Protocyon spp., Theriodictis spp., Canis gezi, Canis nehringi and Canis dirus.
View Article and Find Full Text PDFHere we explore the effect of missing data in phylogenetic analyses using a large number of real morphological matrices. Different percentages and patterns of missing entries were added to each matrix, and their influence was evaluated by comparing the accuracy and error of most parsimonious trees. The relationships between accuracy and error and different parameters (e.
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