Invertebrate trace fossils from the "Upper" Collio Formation (Lower Permian) of the Valtellina area (Orobic basin, Southalpine-Northern Italy-). An observation

• Autores: Giuseppe Santi, Chiara Krieger
• Localización: Batalleria ( Barcelona ): revista de paleontología, ISSN 0214-7831, Nº. 11, 2002-2003, págs. 75-80
• Idioma: inglés
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• Resumen

  • In the upper part off the continental Collio Formation cropping out in the Valtellina area (Orobic Basin, Southalphine) some traces of the freshwater jellyfish (Medusina atava (Pohlig, 1892) are found, together with those of the arthropods (Dendroidichnites elegans Demathieu, Gand and Toutin-Morin 1992), which still haven't been discovered in the Lower Permian of the Alps. The palaeoenvironmental meaning of these fossils is considered different: M. Atava probablt preferred a less wet and probably dryng up habitat, linked to a mosly dry climate, and is absent in the "lower Collio", while D. Elegans, also discovered in the "orobic lower Collio", should constitute a "strong" form which could withstand the environmental changes that occurred at the passage from the "lower Collio" to the "upper" one, in the same way as some vertebrate trackmakers could. (Amphisauropus and Dromopus). The two ichnospecies also have a diffrent geographical distribution: M. Atava is known only in the Lower Permian of Central Europe, while D. Elegans occupies a most cosmopolitan role since it has been found in North America, too.