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Gaudin T.J.,University of Tennessee at Chattanooga | Pujos F.,CONICET | Pujos F.,Institute Francais DEtudes Andines IFEA
Journal of Mammalian Evolution

This special issue of the Journal of Mammalian Evolution represents the proceedings from a symposium held in conjunction with the 9th International Congress of Vertebrate Morphology (ICVM IX, Punta del Este, Uruguay, July 29, 2010), and entitled "Form and Function in the Xenarthra." This symposium was the third on xenarthran biology to be presented in association with the ICVM meetings. In this brief introduction to the symposium proceedings, we plan to discuss the justification for the symposium, to provide a brief history of previous symposia and their results, and to introduce the contents of the present volume. © 2012 Springer Science+Business Media, LLC. Source

Pujos F.,CONICET | Pujos F.,Institute Francais DEtudes Andines IFEA | Gaudin T.J.,University of Tennessee at Chattanooga | de Iuliis G.,University of Toronto | Cartelle C.,PUC Minas
Journal of Mammalian Evolution

The occasion of the Xenarthra Symposium during the ICVM 9 meeting allowed us to reflect on the considerable advances in the knowledge of sloths made by the "X-community" over the past two decades, particularly in such aspects as locomotion, mastication, diet, dental terminology, intraspecific variation, sexual dimorphism, and phylogenetic relationships. These advancements have largely been made possible by the application of cladistic methodology (including DNA analyses) and the discovery of peculiar forms such as Diabolotherium, Thalassocnus, and Pseudoglyptodon in traditionally neglected areas such as the Chilean Andes and the Peruvian Pacific desert coast. Modern tree sloths exhibit an upside-down posture and suspensory locomotion, but the habits of fossil sloths are considerably more diverse and include locomotory modes such as inferred bipedality, quadrupedality, arboreality or semiarboreality, climbing, and an aquatic or semi-aquatic lifestyle in saltwater. Modern tree sloths are generalist browsers, but fossil sloths had browsing, grazing, or mixed feeding dietary habits. Discovery of two important sloth faunas in Brazil (Jacobina) and southern North America (Daytona Beach and Rancho La Brea) have permitted evaluation of the ontogenetic variation in Eremotherium laurillardi and the existence of possible sexual dimorphism in this sloth and in Paramylodon harlani. A new dental terminology applicable to a majority of clades has been developed, facilitating comparisons among taxa. An analysis wherein functional traits were plotted onto a phylogeny of sloths was used to determine patterns of evolutionary change across the clade. These analyses suggest that megatherioid sloths were primitively semiarboreal or possessed climbing adaptations, a feature retained in some members of the family Megalonychidae. Pedolateral stance in the hindfoot is shown to be convergently acquired in Mylodontidae and Megatheria (Nothrotheriidae + Megatheriidae), this feature serving as a synapomorphy of the latter clade. Digging adaptations can only be securely ascribed to scelidotheriine and mylodontine sloths, and the latter are also the only group of grazing sloths, the remainder being general browsers. © 2012 Springer Science+Business Media, LLC. Source

Pujos F.,CONICET | Pujos F.,Institute Francais DEtudes Andines IFEA | Salas-Gismondi R.,Museo de Historia Natural UNMSM | Baby G.,Toulouse 1 University Capitole | And 4 more authors.
Journal of Systematic Palaeontology

Middle Miocene remains of giant megatheriine ground sloths (Tardigrada: Megatherioidea) are scarce and generally located in southern South America. The discovery of a well-preserved edentulous dentary of Megathericulus sp. from the Middle Miocene (Laventan South American Land Mammal Age - SALMA; 13.5-11.8 Ma) of the Amazonian Peru increases our knowledge of this genus, which had previously been recognized in Argentina. A preliminary revision of the earliest Megatheriinae allowed clustering the four middle Miocene species within the genus Megathericulus Ameghino: M. patagonicus Ameghino, M. primaevus Cabrera, M. andinum (Kraglievich), and M. cabrerai (Kraglievich). This small-sized genus is mainly characterized by a lateral depression that borders m1, a posterior external opening of the mandibular canal anterior to the base of the ascending ramus that opens anteriorly or anterodorsally, the base of the symphysis located anteriorly to the m1, important anteroposterior compression of the teeth, elongation of the region of the maxilla anterior to the M1, humerus elongated and gracile, patellar trochlea of femur contiguous with medial and lateral articular facets for tibia, strongly developed odontoid tuberosity, and astragalus with prominent odontoid process. The genus Eomegatherium Kraglievich is therefore restricted to the Huayquerian SALMA of Argentina and represented by a single species, E. nanum Burmeister. Megatheriinae constitute the first clade of Tardigrada in which the caniniform tooth has been secondarily modified into a molariform tooth. Three molariform patterns can be observed during megatheriine evolution in relation to tooth compression and loph or lophid orientation. Middle Miocene Megatheriinae occur only in the westernmost part of South America. These giant ground sloths might have dispersed latitudinally from Colombia/Patagonian Argentina before colonizing eastern areas of Andean South America (Bolivia, Venezuela, north, and east of Argentina) during the late Miocene and early Pliocene. © 2013 Copyright Taylor and Francis Group, LLC. Source

Gaudin T.J.,University of Tennessee at Chattanooga | De Iuliis G.,University of Toronto | De Iuliis G.,Royal Ontario Museum | Toledo N.,Museo de La Plata | And 3 more authors.

New, exceptionally well preserved skulls of the basal megalonychid ground sloth Eucholoeops ingens Ameghino have been recovered through recent field work in the late early Miocene Santa Cruz Formation of southern Argentina (Patagonia, Santacrucian SALMA). These specimens have permitted detailed description of the anatomy of the basicranium, endocranium, and orbital wall, including descriptions of the morphology and sutural relationships of the bones from this portion of the skull, and their associated cranial foramina. Comparisons are made to other megalonychid and megatherioid sloths, including the extant two-toed sloth Choloepus Illiger (Megalonychidae). As the descriptions are based on multiple specimens of E. ingens, we have been able to examine intraspecific variation in the features described, and have found marked differences among individual specimens in sutural patterns (e.g., the bones that surround the foramen ovale aperture), cranial foramina (e.g., the presence/absence of a postglenoid foramen), and bony morphology (e.g., fusion of the alae of the vomer). The basicranial and orbital morphology of Eucholoeops ingens is shown to possess numerous plesiomorphic aspects, including the presence of a descending lamina of the pterygoid that is hemispherical in outline, and the absence of an alisphenoid/parietal contact, no doubt due to its position as the oldest megalonychid known from relatively complete material. The presence of distinct grooves on the promontorial surface directed toward the fenestra ovalis suggest that Eucholoeops ingens may be the only known xenarthran to have retained a functional stapedial artery into adulthood. Source

Frogley M.,University of Sussex | Chepstow-Lusty A.,Institute Francais DEtudes Andines IFEA | Leng M.,NERC Isotope Geosciences Laboratory
Planet Earth

Mick Frogley explains how climate change is threatening water supplies in the highlands of Peru. Against the background of global-warming, the ready availability of fresh water is coming under increasing strain in many parts of the world. Research has focused on understanding changes in climate and water availability in the Peruvian highlands, using evidence preserved in lake mud over thousand years. Lakes often respond to climatic changes in predictable ways and maintain a record of these changes in their sediments. One lake that has behaved just like this is Marcacocha, located about 3350m above sea-level in the Patacancha Valley, itself a tributary to the Sacred Valley of the Incas. The sediments themselves also gave us clues about past conditions. Planting of eucalyptus is increasing pressure on already limited water resources and causing conflict in many Peruvian regions, both in the highlands and in the much more densely populated coastal strip. Source

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