https://eprints.lib.hokudai.ac.jp/dspace/bitstream/2115/49406/1/MPE63-3_745-757.pdf

Evolutionary and biogeographic history of weasel-like carnivorans (Musteloidea).

Fil: Prevosti, Francisco Juan. Consejo Nacional de Investigaciones Cientificas y Tecnicas. Oficina de Coordinacion Administrativa Parque Centenario. Museo Argentino de Ciencias Naturales “Bernardino Rivadavia”; Argentina

Evolution of South American Mammalian Predators During the Cenozoic: Paleobiogeographic and Paleoenvironmental Contingencies

Glyptodonts were giant (some of them up to ~2400 kg), heavily armoured relatives of living armadillos, which became extinct during the Late Pleistocene/early Holocene alongside much of the South American megafauna. Although glyptodonts were an important component of Cenozoic South American faunas, their early evolution and phylogenetic affinities within the order Cingulata (armoured New World placental mammals) remain controversial. In this study, we used hybridization enrichment and high-throughput sequencing to obtain a partial mitochondrial genome from Doedicurus sp., the largest (1.5 m tall, and 4 m long) and one of the last surviving glyptodonts. Our molecular phylogenetic analyses revealed that glyptodonts fall within the diversity of living armadillos. Reanalysis of morphological data using a molecular 'backbone constraint' revealed several morphological characters that supported a close relationship between glyptodonts and the tiny extant fairy armadillos (Chlamyphorinae). This is surprising as these taxa are among the most derived cingulates: glyptodonts were generally large-bodied and heavily armoured, while the fairy armadillos are tiny (~9-17 cm) and adapted for burrowing. Calibration of our phylogeny with the first appearance of glyptodonts in the Eocene resulted in a more precise timeline for xenarthran evolution. The osteological novelties of glyptodonts and their specialization for grazing appear to have evolved rapidly during the Late Eocene to Early Miocene, coincident with global temperature decreases and a shift from wet closed forest towards drier open woodland and grassland across much of South America. This environmental change may have driven the evolution of glyptodonts, culminating in the bizarre giant forms of the Pleistocene.

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Ancient DNA from the extinct South American giant glyptodont Doedicurus sp. (Xenarthra: Glyptodontidae) reveals that glyptodonts evolved from Eocene armadillos

Xenarthra is a monophyletic group, characterized by a particular skeletal architecture, different to other placental mammals. Its current distribution is exclusively Neotropical; however, the fossil record indicates a greater distribution. The aim of this paper is to provide an updated list of the Xenarthra of the lower to middle Pleistocene (Ensenadan Stage) of the Pampean Region (Argentina). The most conspicuous anatomical features that allowed the taxonomic identification of fossil remains, especially those of particular biostratigraphic interest, are also briefly described and figured here. We studied more than 700 fossil remains mostly housed in palaeontological collections of Argentina. The study of these specimens (from the Pampean Region), revealed that during the Pleistocene there were marked variations in the composition and distribution of the faunas in general and particularly in xenarthrans. This situation was closely related to the Great American Biotic Interchange and climatic oscillations occurring in the Pleistocene. Thus, the Ensenadan fossil record of xenarthrans consists on exclusive taxa and numerous cases of first and last records. Finally, we expect that this contribution provide a starting point for future contributions in respect of the Pleistocene fauna, not only from the Pampean Region, but also from the rest of Argentina and South America.

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Los Xenarthra (Mammalia) del Ensenadense (Pleistoceno inferior a medio) de la Región Pampeana (Argentina)

Tayassuidae represent one of the first mammalian immigrants that entered South America during the “Great American Biotic Interchange.” However, the exact moment of its arrival for the first time in South America is controversial. Three genera are recognized in South America: Platygonus, Catagonus, and Tayassu. This paper aims to: (1) review the paleontological record of the South American Tayassuidae and update it; and (2) discuss its geographical and statigraphical distribution pattern in South America. The genus Platygonus (middle Pliocene to early Pleistocene) is registered in Argentina, Uruguay, Colombia, and Bolivia; Catagonus (late Pliocene? to Recent) in Argentina, Uruguay, Brazil, and Bolivia; and Tayassu (middle Pleistocene to Recent) in Argentina, Uruguay, and Brazil. Platygonus and Catagonus have adaptations to dry and relatively open environments; in contrast, Tayassu is adapted mainly to humid climates and woodland and forest environments. The faunal changes that took place since the middle-late Pliocene could have been strongly influenced by climate. Open and arid environments developed during the glacial cycles, allowing the latitudinal expansion of Platygonus and Catagonus. Considering ecological and anatomical information, it is possible to infer that Platygonus species were replaced by those of Catagonus since the middle Pleistocene, probably due to a reduction of the open environments to which Platygonus species were better adapted. The alternation of these mainly arid or semiarid, cold conditions with warmer and more humid short pulses would have allowed the posterior expansion of Tayassu species. According to phylogenetic analysis and chronological as well as geographical evidence, Platygonus and Catagonus represent two Tayassuidae lineages that originated in North America and then migrated to South America. This migration would have occurred on more than one occasion and with different taxa. Evidence indicates that Tayassu represents a lineage that differentiated in the Southern Hemisphere and then migrated to North America.

Records and Stratigraphical Ranges of South American Tayassuidae (Mammalia, Artiodactyla)

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Faunistic analisys of vertebrates from las toscas del Río de La Plata (Buenos Aires, Argentina): a palaeontological site in disappearance

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

Accessory protection structures in Glyptodon Owen (Xenarthra, Cingulata, Glyptodontidae) Structures accessoires de protection en Glyptodon Owen (Xenarthra, Cingulata, Glyptodontidae)

Fossil remains of South American tapirs are often fragmentary and scarce compared with those of other mammals that entered South America during the “Great American Biotic Interchange”. Here, we review and add to the Pleistocene tapir remains from the Tarija Valley (Bolivia), and provide a taxonomic re-evaluation of Tapirus tarijensis. T. tarijensis was a large-sized animal, approximating the size of the living Malaysian T. indicus and the extinct North American T. haysii. The geographical distribution of Pleistocene records of Tapirus in South America indicates that T. tarijensis was the only known species inhabiting the Tarija Valley during this time.

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Germán Mariano Gasparini

Papers

Faunistic analisys of vertebrates from las toscas del Río de La Plata (Buenos Aires, Argentina): a palaeontological site in disappearance

Accessory protection structures in Glyptodon Owen (Xenarthra, Cingulata, Glyptodontidae) Structures accessoires de protection en Glyptodon Owen (Xenarthra, Cingulata, Glyptodontidae)

A Taxonomic and Biogeographic Review of the Fossil Tapirs from Bolivia