科研之友
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摘要
A plant fossil assemblage (micro-and macroflora) from the northern sector of Nelson Island (Rip Point) is abborded on its composition and age. The macroflora shows few ferns and a conifer remain (cf. Papuacedrus) and dominant angiosperm fossil leaves represented by laurophyll (probable Elaeocarpaceae/Anacardiaceae affinity), acrodromophyll (Melastomaceae?) and protophyll (Nothofagaceae) morphotypes. The absence of marginal characters in great part of the leaf remains incentivate their treatment by morphological groups, trying to guarantees at least the stablishment of its relation with other extant and fossil assemblages and the reconstructions of the geological process implied in its preservation. The microflora shows a distinct composition, with many fern and fungal spores and pollen grains of gymnosperms, with a minor component in angiosperms (Proteacea, Aquifoliacea and primitive Nothofagus). The presence of Classopollis and "ancestral" forms of Nothofagidites pollen grains indicate a CampanianLower Maastrichtian age to the Rip Point succession, where the occurrence of a probable Papuacedrus and Melastomataceae related forms have a strong evolutive value and phyllogenetic implications, could being its anciest know record. Leaves of deciduous Nothofagus dominate the macroflora and probably include juvenile forms. Fungi spores and foraminifera indicate a near-coast lake environment to the deposit, and the floristic composition, the remobilization of the leaf remains from a vegetation growing on the slopes of the proximal volcanoes. Comparable extant analogues grows today in rain forests of southern South America and New Zealand, and allows to infer a wet temperate to subtropical climate to the north of Antarctic Peninsula in the end of Cretaceous.
- 出版日期2013-12
