Hallazgo de Neozamites (Bennettitales) en el Cretácico Inferior de la isla Snow, Shetland del Sur, Antártica.
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Date
1998
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Abstract
Se describen plantas fósiles halladas en los sedimentos del Cretácico Inferior expuestos en la localidad de President Head, en la isla Snow (62°44'S, 61°12'W) archipiélago Shetland del Sur. Las impresiones
de hojas son de gran talla, con foliolos largos y angostos con mas de 14 cm de largo, insertos en el tallo por una callosidad basal. Por el borde dentado, a partir de mitad superior, y las nervaduras que parten de la base dicotomisándose sucesivamente hacia el ápice y hacia los bordes, se clasifica a esta planta en el genero Neozamites Vakhrameev, (Bennettitales) y se propone una nueva especie: Neozamites hervei.
El genero se describe por primera vez para la Antártica. EI interés de este hallazgo radica en su posición estratigráfica y geográfica. Neozamites es conocido solo en el Cretácico Inferior y los registros
anteriores corresponden a China, Japón y Rusia. Se discuten consideraciones paleo-ecológicas y se confirma la edad anteriormente propuesta para los estratos con plantas fósiles en la isla Snow.
The fossil specimens found in the Early Cretaceous sediments exposed in President Head (62°44' S, 61°12'W) from Snow Island, South Shetland Islands, are described. They are characterised by large leaves with leaflets of more than 14 cm. the pinna with cordate base are attached to the rachis by a narrower central zone. The upper part of the leaflet is characterized by subopposite teeth orientated towards the acute apex. The venation is diverging dichotomously forking near the distal part. All-these characters permit to attribute the specimens to the genus Neozamites Vakhrameev (Bennettitales), and N. hervei .sp. nov., is proposed. This genus is found for the first time in Antarctica. The interest of this discovery is the geographical and stratigraphical distribution. The genus has been found only in the Early Cretaceous sediments in Siberia, China and an inner zone in Japan. The palaeoecological considerations are also discussed and the age for the strates with fossil plants is confirmed.
The fossil specimens found in the Early Cretaceous sediments exposed in President Head (62°44' S, 61°12'W) from Snow Island, South Shetland Islands, are described. They are characterised by large leaves with leaflets of more than 14 cm. the pinna with cordate base are attached to the rachis by a narrower central zone. The upper part of the leaflet is characterized by subopposite teeth orientated towards the acute apex. The venation is diverging dichotomously forking near the distal part. All-these characters permit to attribute the specimens to the genus Neozamites Vakhrameev (Bennettitales), and N. hervei .sp. nov., is proposed. This genus is found for the first time in Antarctica. The interest of this discovery is the geographical and stratigraphical distribution. The genus has been found only in the Early Cretaceous sediments in Siberia, China and an inner zone in Japan. The palaeoecological considerations are also discussed and the age for the strates with fossil plants is confirmed.
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Keywords
Bennettitales, Plantas fósiles, Cretácico inferior, Paleogeografía
Citation
Serie Científica, nº 48, pp. 9-18, 1998