Paläontologische Zeitschrift, 2016

Pyroclastic and epiclastic continental sediments bearing the ''fauna Astrapothericulense'' from the Pinturas Formation of Ameghino crop out mainly at several localities at the upper valley of the Pinturas River and its tributaries, northwestern Santa Cruz Province, Argentina. These continental sediments are referred to the Burdigalian Stage and constitute the basis for the recognition of the Pinturas Formation. The fauna recorded in the Pinturas Formation mainly consists of mammals, specially rodents, native ungulates, xenarthrans and primates. Here we describe the first association of Megatherioidea (Mammalia, Xenarthra, Tardigrada) from different localities of the Pinturas Formation with accurate geographic and stratigraphic provenance. The Megatherioidea from the Pinturas Formation presented herein are represented by (1) Schismotherium cf. binum; (2) Hapalops sp.; and (3) a Megatherioidea indet. In addition, the holotypes of Schismotherium binum (MACN A 11750), Hapalops curvus (MACN A 11140), and Pelecyodon arcuatus were collected from the ''fauna Astrapothericulense'' of Ameghino; unfortunately, it is not easy to determine if they were collected from the Pinturas Formation since they are part of Ameghino's Collection (MACN), but were collected a time when the Pinturas Formation had not yet been proposed. The presence of a species of Schismotherium and of Hapalops in the Pinturas Formation represent accurate early records for these genera, but not necessarily the earliest. The age of the Pinturas Formation could overlap, partially or totally, with the age of the Santa Cruz Formation at the Atlantic coast, where most Early Miocene Megatherioidea were collected. Keywords Ground sloths Á Burdigalian stage Á Diversity Á South America Kurzfassung Verschiedene Fundstellen mit vulkanoklastischen und epiklastischen Sedimenten im oberen Tal des Pinturas-Flusses und dessen Nebenflüssen im Nordwesten der Provinz Santa Cruz in Argentinien enthalten die

In this contribution we describe a partial dentary with teeth and an astragalus referred to the ancient megatheriine Megathericulus patagonicus Ameghino, 1904 (Xenarthra, Tardigrada) recovered from the Collón Curá Formation (Miocene) at Chubut Province, Argentina. Referral of the new specimens is based on metric and morphological similarities with the holotype and specimens that have been referred to this species. Shared features include: 1) overall size, smaller than other Megatheriinae such Eomegatherium Kraglievich, 1926, Pliomegatherium Kraglievich, 1930, and Pyramiodontherium (Rovereto, 1914); 2) shape of the molariforms, molariforms mesiodistally compressed and rectangular in outline; 3) Hypsodonty Index close to 100; 4) position of the navicular facet, two-thirds of the navicular facet projects dorsal to the discoid facet; 5); shape of the ventral portion of the fibular facet, the ventral portion has subtriangular outline and contacts the ectal facet; 6) in the astragalus, presence of a sesamoid facet. Considering the large intraspecific differences exhibited in Megatheriinae, the similarities and few differences between Megathericulus primaevus Cabrera, 1939, and M. patagonicus allow us to consider M. primaevus as a junior synonym of M. patagonicus. The presence of Megathericulus and 'Xyophorus' Ameghino, 1887 (Mammalia, Xenarthra, Nothrotheriinae) in some distant paleofauna associations (Cerro Zeballos, Argentina, and Quebrada Honda, Bolivia) would suggest a similar path of dispersion and paleoenvironment requirements of both taxa. The presence of these two genera in mentioned localities supports that the Quebrada Honda fauna as a whole is more similar to the asynchronous high-latitude faunas from Patagonia than to contemporary La Venta Fauna (Colombia).

The genus Megatherium includes nearly ten species that are distributed along the Pleistocene of South America. In contrast with the abundant and geographically widespread Pleistocene record, remains of Pliocene Megatherium are restricted to a single and poorly known species from the highlands of Perú. The aim of the present contribution is to describe a skull referable to the genus Megatherium coming from Late Pliocene beds at the San Eduardo del Mar locality, Buenos Aires Province, Argentina. This constitutes the first undoubted record of Megatherium from the Pliocene of Argentina, and one of the oldest records for the genus. This finding blurs previous biogeographical proposals sustaining that the genus originated in the High Andes and later dispersed to the lowlands. On the contrary, present finding, together with the record of coeval Megatherium species in the Pleistocene of the Argentine Pampas, suggests a more complex palaeobiogeographical scenario and indicates that the diversity of lowland Pliocene megatheriines is still underrepresented.

2016

ABSTRACT. Late Miocene f luvial strata of the Palo Pintado Formation are broadly exposed to the northwest of the town of Angastaco, Salta province, Northwest of Argentina. These strata accumulated in the extensional Angastaco Basin. Recent field work at the Palo Pintado Formation (late Miocene), Valle Calchaquí, Salta province, Argentina has provided fossil remains that greatly increased the knowledge of the faunal assemblage of this site. A number of notoun-gulates and rodents were collected. A partial left jaw was collected at Quebrada Peñas Blancas along the west bank of the Río Calchaquí. Morphological and morphometric comparisons permit referral of this specimen to a new species of hegetotheriid notoungulate Paedotherium kakai sp. nov. It represents the first report of Paedotherium for the Eastern Cordillera and one of the few well-documented occurrences of this genus outside of middle-high latitudes Argentina. The widespread geographic range of Paedotherium, combined with its ...

Geodiversitas, 2008

The Megatheriinae (Mammalia, Xenarthra, Megatheriidae) are recorded in Argentina from the middle Miocene to the early Holocene. Only the genus Megatherium, comprising several species of controversial validity, is recognized for the Pleistocene of the Pampean region. Megatherium americanum is the best studied species and occurs frequently in sediments assigned to the Lujanian stage [Equus (Amerhippus) neogeus Biozone, c. 0.13-0.08 My). On the other hand, M. gallardoi and M. silenum, both from Ensenadan sediments (Mesotherium cristatum Biozone) of Buenos Aires Province, have been considered by some authors as synonyms ofM americanum. The main goal of this contribution is to complete the description of M. gallardoi, clarify its taxonomic status, and establish its relationships with other megatheriines. The most remarkable features of M. gallardoi are: premaxillae not fused to each other or to the maxillae; mandibular ramus relatively low; femur with lateral and medial diaphyseal margin...

Geodiversitas, 2004

Journal of South American Earth Sciences, 2020

New remains of fossil vertebrates recovered from two localities in Entre Ríos Province, Argentina, are studied. The specimens were found at Toma Vieja and Arroyo Chapetón localities, where the fossiliferous Lower Member (“Mesopotamiense”, Late Miocene) of Ituzaingó Formation (Late Miocene–Pliocene) crops out. The new findings contribute to the high diversity of fossil vertebrates largely known for this unit. The specimens correspond to Perciformes indet. and Pimelodidae indet. (Pisces), Macranhinga paranensis (Aves), Scirrotherium carinatum, Brachytherium cuspidatum, Proterotheriinae indet., Hydrochoerinae indet., and cf. Prodolichotis (Mammalia). Considering the relationship between the fauna present in this unit and that from other mammal-bearing Neogene units (e.g., Arroyo Chasicó, Andalhuala, Cerro Azul, and Monte Hermoso formations), the “Mesopotamiense” is a faunal combination of Chasicoan and Huayquerian taxa deposited during the end of the Tortonian or the early Messinian. From a paleoenvironmental point of view, the “Mesopotamiense” faunal