First gondwanatherian mammal from Antarctica
Francisco J. Goin, Marcelo A. Reguero, Rosendo Pascual, Wighart Von Koenigswald, Michael O. Woodburne, Judd A. Case, Sergio A. Marenssi, Carolina Vieytes, Sergio F. Vizcaíno, 2006. "First gondwanatherian mammal from Antarctica", Cretaceous–Tertiary High-Latitude Palaeoenvironments: James Ross Basin, Antarctica, J. E. Francis, D. Pirrie, J. A. Crame
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Gondwanatherians are an enigmatic group of extinct non-therian mammals apparently restricted to some of the western Gondwanan continents (Late Cretaceousearly Palaeocene of South America, and Late Cretaceous of Madagascar and India). They developed rodent-like incisors and the earliest known hypsodont cheek-teeth among mammals. Recently, a small rodent-like dentary fragment was recovered from middle Eocene beds on the Antarctic Peninsula, preserving part of the incisor; both the incisor enamel structure and the mandibular morphology suggest close affinities with Sudamerica ameghinoi from the early Palaeocene of Patagonia, up to now the youngest known Gondwanatheria. Thus, the new specimen becomes the youngest occurrence of a gondwanathere, adding significant direct and indirect evidence on: (1) the already documented cosmopolitanism of gondwanatheres among Gondwanan mammals; and (2) the crucial biogeographical role of Antarctica during the Cretaceous–Tertiary mammalian transition.
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High-latitude settings are sensitive to climatically driven palaeoenvironmental change and the resultant biotic response. Climate change through the peak interval of Cretaceous warmth, Late Cretaceous cooling, onset and expansion of the Antarctic ice sheet, and subsequently the variability of Neogene glaciation, are all recorded within the sedimentary and volcanic successions exposed within the James Ross Basin, Antarctica. This site provides the longest onshore record of Cretaceous–Tertiary sedimentary and volcanic rocks in Antarctica and is a key reference section for Cretaceous–Tertiary global change. The sedimentary succession is richly fossiliferous, yielding diverse invertebrate, vertebrate and plant fossil assemblages, allowing the reconstruction of both terrestrial and marine systems. The papers within this volume provide an overview of recent advances in the understanding of palaeoenvironmental change spanning the mid-Cretaceous to the Neogene of the James Ross Basin and related biotic change, and will be of interest to many working on Cretaceous and Tertiary palaeoenvironmental change.