The Tardigrada (Mammalia, Xenarthra) of Argentina: Diversity, evoltion and biogeography

Los Tardigrada representan uno de los grupos de mamíferos fósiles característicos del Cenozoico de América del Sur, pero que también se encuentra representado en América Central y América del Norte. El registro fehaciente más antiguo del grupo correspondería a Pseudoglyptodon del Eoceno tardío de Chubut, y en la actualidad está representado por los géneros arborícolas Bradypus y Choloepus. El registro fósil da cuenta de una gran diversidad taxonómica de tardígrados, con más de 50 géneros bien conocidos, con formas arborícolas, semiarborícolas y cursoriales. Tardigrada incluye cuatro clados principales: Megatheriidae, Megalonychidae, Nothrotheriidae y Mylodontidae, a los que suma una serie de géneros conocidos como Megatherioidea basales. A partir del Oligoceno tardío se hacen abundantes y están representados por varias líneas de Megatherioidea y Mylodontoidea. Durante el Neógeno (Mioceno–Plioceno) el grupo alcanza una alta diversidad con representantes de todas las familias. Durante el Cuaternario algunos géneros alcanzan los mayores tamaños (e.g., Megatherium, Lestodon) y forman parte de las asociaciones conocidas como megafauna. Hacia el final del Pleistoceno e inicio del Holoceno las formas de perezosos de gran tamaño se extinguen junto con otros elementos de la megafauna.The Tardigrada represent one of the most characteristic groups of fossil mammals from the Cenozoic of South America, but they are also present in Central and North America. The oldest record would correspond to Pseudoglyptodon from the Eocene of Chubut Province, and at the present, the group is represented by the arboreal genera Bradypus and Choloepus. The fossil record shows a great diversity, with more than 50 genera well known, with arboreal, semiarboreal and cursorial forms. Tardigrada include four main clades: Megatheriidae, Megalonychidae, Nothrotheriidae and Mylodontidae; and a group of genera known as basal Megatherioidea. At the beginning of the late Oligocene the group became abundant and it is represented by several lineages of Megatherioidea and Mylodontoidea. During the Neogene (Miocene–Pliocene) the group reaches a high diversity, including genera of all the families. During the Quaternary, some genera reaches great sizes (e.g., Megatherium, Lestodon) forming part of the faunistic associations called megafauna. Until the end of the Pleistocene and the beginning of the Holocene the ground sloths of great size became extinct along with other elements of the megafauna.Fil: Brandoni, Diego. Provincia de Entre Ríos. Centro de Investigaciones Científicas y Transferencia de Tecnología a la Producción. Universidad Autónoma de Entre Ríos. Centro de Investigaciones Científicas y Transferencia de Tecnología a la Producción. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe. Centro de Investigaciones Científicas y Transferencia de Tecnología a la Producción; ArgentinaFil: Scillato Yané, Gustavo J.. Universidad Nacional de La Plata. Facultad de Ciencias Naturales y Museo. División Paleontología Vertebrados; ArgentinaFil: Miño Boilini, Ángel Ramón. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Nordeste. Centro de Ecología Aplicada del Litoral. Universidad Nacional del Nordeste. Centro de Ecología Aplicada del Litoral; ArgentinaFil: Favotti, Sergio Emmanuel. Provincia de Entre Ríos. Centro de Investigaciones Científicas y Transferencia de Tecnología a la Producción. Universidad Autónoma de Entre Ríos. Centro de Investigaciones Científicas y Transferencia de Tecnología a la Producción. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe. Centro de Investigaciones Científicas y Transferencia de Tecnología a la Producción; Argentin

New Early Eocene Mammalian Fauna from Western Patagonia, Argentina

Two new fossil mammal localities from the Paleogene of central-western Patagonia are preliminarily described as the basis for a new possible biochronological unit for the early Eocene of Patagonia, correlated as being between two conventional SALMAs, the Riochican (older) and the Vacan subage of the Casamayoran SALMA. The mammal-bearing strata belong to the Middle Chubut River Volcanic-Pyroclastic Complex (northwestern Chubut Province, Argentina), of Paleocene-Eocene age. This complex includes a variety of volcaniclastic, intrusive, pyroclastic, and extrusive rocks deposited after the K-T boundary. Geochronological data taken from nearby volcanic deposits that underlie and overlie the mammal-bearing levels indicate that both faunas are of late early Eocene age (Ypresian-Lutetian boundary). In addition to more than 50 species of mammals, including marsupials, ungulates, and xenarthrans, two lower molars are the oldest evidence of bats in South America. Paleobotanical and palynological evidence from inferred contemporary localities nearby indicate subtropical environments characterized by warm and probably moderately humid climate. Remarkably, this new fauna is tentatively correlated with Eocene mammals from the La Meseta Formation in the Antarctic Peninsula. We conclude that the two localities mentioned above are part of a possible new biochronological unit, but the formal proposal of a new SALMA awaits completion of taxonomic analysis of the materials reported upon here. If the La Meseta fauna is correlated biochronologically to western Patagonia, this also suggests a continental extension of the biogeographic Weddelian Province as far north as central-western Patagonia.Facultad de Ciencias Naturales y Muse

Le pied de <i>Pyramiodontherium bergi</i> (Moreno & Mercerat, 1891) (Mammalia, Xenarthra, Phyllophaga) : le pied le plus complet d’un Megatheriinae tertiaire

Ce travail se propose de compléter la description du seul pied complet de mégathère tertiaire connu et ainsi de pouvoir réaliser des comparaisons avec ceux des autres membres de la sous-famille. Le pied complet de l’holotype de Pyramiodontherium bergi (Moreno &amp; Mercerat, 1891) (MLP 2-66) provient du niveau « Araucanense » s.l. de Bajo de Andalhuala, Province de Catamarca (Miocène supérieur-Pliocène), Argentine. Les éléments du pied présentent la structure habituellement rencontrée chez les mégathères. Cependant, la dépression astragalienne est moins profonde que chez Megatherium americanum Cuvier, 1796 et le calcanéum est moins gracile que chez Eremotherium Laurillardi (Lund, 1842). Le naviculaire présente deux facettes articulaires pour l’ectocunéiforme. Le pied est constitué de sept éléments (calcanéum, astragale, naviculaire, entocunéiforme, mésocunéiforme, ectocunéiforme et cuboïde) alors que chez les autres mégathères dont le pied est connu, mésocunéiforme et entocunéiforme sont fusionnés en un seul élément, dénommé complexe méso-entocunéiforme. Le troisième doigt n’est constitué que de deux phalanges, la phalange proximale résultant de la fusion de deux phalanges. Contrairement à tous les mégathères quaternaires, le doigt IV de P. bergi possède trois phalanges. La présence d’un entocunéiforme et d’un mésocunéiforme séparés ainsi que de trois phalanges pour le doigt IV chez le genre plio-pléistocène est considérée ici comme étant la condition primitive. Les états de caractères plésiomorphes présents ici pourraient aider à résoudre la polytomie des mégathères proposée par De Iuliis (1996) ainsi qu’à appréhender leurs différents changements.The aim of this paper is to enlarge the description of the only known complete pes of a Tertiary megatherine and make comparisons with those of other members of the subfamily. The complete pes of the type specimen of Pyramiodontherium bergi (Moreno &amp; Mercerat, 1891) (MLP 2-66) was found at the informally named “Araucanense” s.l. levels of Bajo de Andalhuala, Catamarca Province (late Miocene-Pliocene), Argentina. The elements of the pes show the general characters of other megatherines. However, the astragalar depression is not as deep as in Megatherium americanum Cuvier, 1796; the calcaneum is more slender than Eremotherium laurillardi (Lund, 1842); the navicular has two facets to articulate with the ectocuneiform; there are seven separate tarsal elements (calcaneum, astragalus, navicular, entocuneiform, mesocuneiform, ectocuneiform, and cuboid) while in other megatherines, usually the mesocuneiform and the entocuneiform are fused into a single element termed the mesoentocuneiform complex; the third digit is formed only by the proximal phalanx fused with the second phalanx, and digit IV, unlike Quaternary megatherines, has three phalanges. The presence of separated entocuneiform and mesocuneiform and three phalanges in the digit IV, are interpreted as plesiomorphic condition of the characters present in the Plio-Pleistocene genera. The plesiomorphic character states observed here could be useful to solve the megatherine polytomy proposed by De Iuliis (1996), and indicate more precisely the way the states of the characters were changed.</p

A new species of Peltephilidae (Mammalia: Xenarthra: Cingulata) from the late Miocene (Chasicoan SALMA) of Argentina

González-Ruiz, Laureano R., Scillato-Yané, Gustavo J., Krmpotic, Cecilia M., Carlini, Alfredo A. (2012): A new species of Peltephilidae (Mammalia: Xenarthra: Cingulata) from the late Miocene (Chasicoan SALMA) of Argentina. Zootaxa 3359: 55-64, DOI: 10.5281/zenodo.21031

Eocene mammals from western Patagonia.

43 p. : ill., map ; 26 cm. "March 31, 2009." Includes bibliographical references (p. 38-43).Two new fossil mammal localities from the Paleogene of central-western Patagonia are preliminarily described as the basis for a new possible biochronological unit for the early Eocene of Patagonia, correlated as being between two conventional SALMAs, the Riochican (older) and the Vacan subage of the Casamayoran SALMA. The mammal-bearing strata belong to the Middle Chubut River Volcanic-Pyroclastic Complex (northwestern Chubut Province, Argentina), of Paleocene-Eocene age. This complex includes a variety of volcaniclastic, intrusive, pyroclastic, and extrusive rocks deposited after the K-T boundary. Geochronological data taken from nearby volcanic deposits that underlie and overlie the mammal-bearing levels indicate that both faunas are of late early Eocene age (Ypresian-Lutetian boundary). In addition to more than 50 species of mammals, including marsupials, ungulates, and xenarthrans, two lower molars are the oldest evidence of bats in South America. Paleobotanical and palynological evidence from inferred contemporary localities nearby indicate subtropical environments characterized by warm and probably moderately humid climate. Remarkably, this new fauna is tentatively correlated with Eocene mammals from the La Meseta Formation in the Antarctic Peninsula. We conclude that the two localities mentioned above are part of a possible new biochronological unit, but the formal proposal of a new SALMA awaits completion of taxonomic analysis of the materials reported upon here. If the La Meseta fauna is correlated biochronologically to western Patagonia, this also suggests a continental extension of the biogeographic Weddelian Province as far north as central-western Patagonia.Published by the American Museum of Natural History, New York, NY