U-Pb zircon contraints on the age of the Cretaceous Mata Amarilla Formation, Southern Patagonia, Argentina: its relationship with the evolution of the Austral Basin

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Notonuphar antarctica, an extinct water lily (Nymphaeales) from the Eocene of Antarctica

A new genus and species, Notonuphar antarctica, is described from the Eocene of Seymour (Marambio) Island, the Antarctic Peninsula and assigned to the Nymphaeales based on well-preserved seeds. This is the first record of a water lily from Antarctica and the first record of a Gondwanan plant with close link to the genus Nuphar (Nymphaeaceae), which is restricted today to the Northern Hemisphere. Critical features for systematic placement of Notonuphar are the presence of a germination cap with closely spaced hilar scar and micropyle, anatropous, bitegmic and exotestal seed organization, exotesta composed of one cell layer of high sclerenchymatic palisade-shape cells, mesotesta of smaller, low parenchymatic cells, a few cell layers deep, and a thin tegmen. The seeds of Notonuphar are particularly similar to seeds of extant and fossil Nuphar in the straight, unfolded anticlinal wall of the exotestal cells and the presence of a narrow zone of exotestal tissue between hilum and micropyle. Other seed features including the very tall exotestal cells and strongly thickened cell walls of exotesta also link Notonuphar to Brasenia and related fossil taxa (Cabombaceae). This character mosaic observed in Notonuphar corroborates the transitional position of Nuphar between Cabombaceae and Nymphaeaceae. Notonuphar is the only member of Nymphaeales recorded from Antarctica and so far the only fossil seeds of Nymphaeales known from the Southern Hemisphere. The discovery of this extinct Gondwanan taxon with features suggesting close relationship with extant Northern Hemisphere genus Nuphar is a further evidence for the relictual nature of the extant group.Other funding from:Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET Grant PIP 0462 to MAR.), the Argentine National Agency for Promotion of Science and Technology (ANPCyT Grant PICTO-2010–0093 to MAR) and the Paul Scherrer Institute https://www.psi.ch/useroffice/useroffice (projects 20130185, 20141047, 2016140)</p

The Patagonian Fossil Lizards

The squamates constitute a significant part of the present-day South American herpetofauna, being their fossils a crucial evidence for understanding the origin and evolution of the main clades. The fossil record of squamates in Patagonia is still scarce but it represents one of the most prolific of entire South America. An updated systematic review of the available information of Patagonian fossil lizards is summarized in this chapter. The oldest lizards of Patagonia are found as back as the Upper Cretaceous and include materials referred to two of the most diverse extant clades: Iguania and Scincomorpha. Palaeocene and Eocene interestingly do not provide any lizard specimen from this region. The record reappeared in the Late Oligocene with iguanians. A significant increasing of materials is revealed later in the Neogene. Early Miocene lizards include the first appearance of extant species (the iguanids Liolaemus and Pristidactylus, and the teiids Tupinambis and Callopistes). Late Early Miocene deposits provide materials of Pristidactylus and Tupinambis, whereas an indeterminate tupinambine of the Mid-Miocene is the youngest Neogene record of a lizard in Patagonia. Palaeoclimatic changes affected the distributional patterns of lizards in Patagonia, restricting the distribution of Pristidactylus and Tupinambis which, during the Miocene, reached localities southern than at present. The uplift of the austral Andean cordillera would have been decisive for the diversification of Liolaemus and Pristidactylus at both sides the Andes, whereas the trans-Andean teiid Callopistes had a widespread distribution in the past, reaching the Pampean Region and Patagonia, in Argentina.Fil: Albino, Adriana Maria. Universidad Nacional de Mar del Plata. Facultad de Ciencias Exactas y Naturales. Departamento de Biología; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mar del Plata; Argentin

Reigitherium (Meridiolestida, Mesungulatoidea) an Enigmatic Late Cretaceous Mammal from Patagonia, Argentina: Morphology, Affinities, and Dental Evolution

New dental and dentary fossils collected in the Upper Cretaceous La Colonia Formation in central Patagonia provide new evidence on the morphology, feeding ecology, and relationships of the enigmatic mammal Reigitherium. The newly discovered specimens described here include elements of the upper dentition and several partial dentaries, elucidating fundamental questions of serial homology and postcanine dental formula (four premolars and three molars). This new evidence supports a nested position of Reigitherium within the advanced meridiolestidan clade Mesungulatoidea. Apomorphic features of the upper and lower molariform elements include intense enamel crenulation circumscribed within the primary trigon and trigonid, elevated cingulids, and the neomorphic appearance of cusps/cuspulids, all of which increase overall crown complexity. A Dental Topography Analysis comparing Reigitherium and its sister taxon Peligrotherium to Cretaceous and Cenozoic therians demonstrates functional similarity between the mesungulatoids and South American marsupial taxa that succeed them in the small-to medium-sized herbivore niche during the Paleocene. Previous taxonomic attributions of Reigitherium are discussed and comparisons with other meridiolestidans highlight the remarkable radiation of this group in the Cretaceous of South America.Fil: Harper, Tony. University Johns Hopkins; Estados UnidosFil: Parras, Ana Maria. Consejo Nacional de Investigaciones Científicas y Técnicas. Instituto de Ciencias de la Tierra y Ambientales de La Pampa. Universidad Nacional de La Pampa. Facultad de Ciencias Exactas y Naturales. Instituto de Ciencias de la Tierra y Ambientales de La Pampa; ArgentinaFil: Rougier, G. W.. University of Louisville; Estados Unido