"Annularia mucronata Schenk, un taxón paleoecuatorial en la flora eopérmica de la Formación Río Genoa, Chubut, Argentina"

Rubén Cúneo


"Well preserved whorled axes of Annularia rnucronaia Schenk are
described. Morphological attributes as well as some epidermic/hypodermic features preserved as impressions,
allow a complete assignation of the studied material to the amerosinian species. This record
from the lowermost Permian of Patagonia is the earliest stratigraphical occurrence of the genus in the
southern hemisphere. Based on the exclusive distribution of the taxon along the paleoecuatorial belt, a
characteristic also shown by other plant taxa from the Río Genoa Formation, the record of this taxon might
be the result of an ecotonal geographical location of Patagonia during la test Carboniferous-earliest
Permian times. lt is also suggested that a radiation of this group of calamitalean sphenophytes was initiated
from the Patagonian area, arriving later, by the late-Early Permian, to other western Gondwana areas
such as Brazil and South Africa, also involving an speciation process."

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