A new anatomically preserved flora from the Mississippian of Sierra de Las Minitas (La Rioja, Argentina)

PRESTIANNI, C.R.; RUSTÁN, JUAN JOSÉ; BALSEIRO, DIEGO; VACCARI, NORBERTO EMILIO; STERREN, ANDREA; SFERCO, MARTA EMILIA

Congreso; Agora paleobotánica; 2015

A new anatomically preserved flora has been discovered in the Sierra de Las Minitas, a set of low mountains located approximately 30 km to the southwest of the small town of Jagüé, northernmost Precordillera, La Rioja Province, western Argentina. Fossils were collected from a virtually unexplored section, in a very complex stratigraphic and structural setting. Preserved inside nodules, plant remains come from an interval of a thick siliciclastic succession, mainly composed by yellowish to greenish shales and siltites, subordinated sandstone and conglomerate layers and diamictitic deposits. Brachiopods and corals in a number of levels indicate that marine deposits are at least partially represented. In addition, an exquisitely preserved fish assemblage has been identified associated with the fossil flora in similar nodules.Since the paleontological survey of the area is still preliminar, fossils could not be referred to a formal stratigraphic unit. In turn, due to the absence of reliable biostratigraphic indicators and radiometric data, just a broad Mississippian age is interpreted for the fossil-bearing strata.Under progress, the study of the flora has revealed a diverse assemblage comprised of nearly? arborescent Lycopsids, Ferns (cladoxyls and zygopterids), seed plant rachises and stems. Given the depauperate nature of previously known floras from the Mississippian of southern South America, these diverse anatomically preserved records may shed light on the ecological, biogeographical and evolutionary history of high latitude Gondwanan floras..