page_title: Paleobiota of the Posidonia Shale
section_title: Pinophyta
hierarchical_section_title: Paleobiota of the Posidonia Shale / Plantae / Pinophyta
caption_attribution_description: Español: Reconstrucción artística del vegetal Araucarioxylon arizonicum según las descripciones dadas para la especie a partir de sus restos fósiles del Triásico. La altura máxima estimada para la especie es de 60 metros y su diámetro de 60 centímetros. Se observa el tronco columnar con ramificación monopódica y las ramas laterales crecen con un ángulo de 90º respecto al eje y presentan geotropismo negativo. La estructura de las hojas es desconocida.
context_page_description: The Posidonia Shale or Posidonienschiefer Formation is a geological formation of southwestern Germany, northern Switzerland, western Czech Republic, northwestern Austria, southeast Luxembourg and the Netherlands, that spans about 3 million years during the Early Jurassic period. It is known for its detailed fossils, especially sea fauna, listed below. Composed mostly by black shale, the formation is a Lagerstätte, where fossils show exceptional preservation, with a thickness that varies from about 1 m to about 40 m on the Rhine level, being on the main quarry at Holzmaden between 5 and 14 m. Some of the preserved material has been transformed into fossil hydrocarbon Jet, specially wood remains, used for jewelry. The exceptional preservation seen on the Posidonia Shale has been studied since the late 1800s, finding that a cocktail of chemical and environmental factors let to such an impressive conservation of the marine fauna. The most common theory is the changes on the oxygen level, where the different anoxic events of the Toarcian left oxygen-depleted bottom waters, with the biota dying and falling to the bottom without any predator able to eat the dead bodies.
caption: Araucarioxylon reconstruccion
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