INIBIOMA   20415
INSTITUTO DE INVESTIGACIONES EN BIODIVERSIDAD Y MEDIOAMBIENTE
Unidad Ejecutora - UE
congresos y reuniones científicas
Título:
Mid Cretaceous ferns from the Austral Basin, Argentina
Autor/es:
ARI IGLESIAS; AUGUSTO VARELA; MAURO G. PASSALIA; POIRE DANIEL; PATRICIO SANTAMARINA
Lugar:
General Roca
Reunión:
Congreso; Congreso de la Asociación Paleontológica Argentina; 2016
Institución organizadora:
Asociación Paleontológica Argentina
Resumen:
New mid-Cretaceous fern records from the Piedra Clavada and Mata Amarilla Formations,located at Tres Lagos town, Santa Cruz Province, are described. The macrofloristic assemblages throughout all the section show that the angiosperms are the main component ofthe flora by richness and relative abundance since the earliest Cenomanian. In thiscontribution we focused on the pteridophyte records that are also quite diverse. They includesterile and fertile leptosporangiate fern fronds and consist of a typical middle Cretaceous fernflora, with elements shared to others coetaneous assemblages of southern Gondwana. At leastthree taxonomic groups are present throughout the analyzed sections: Matoniaceae,Schizaeaceae and Korallipteris-like fronds (Gleicheniaceae?/Cyatheaceae?/Lophosoriaceae?).However, some relative abundance changes may be related to environmental differences. Themiddle levels of the Piedra Clavada Formation (upper Albian), interpreted as a sandy deltaicenvironment, are dominated by fertile Matoniaceae accompanied by Equisetaceae in liveposition. In the uppermost Piedra Clavada section (lowermost Cenomanian) fertileDennstaedtiaceae have been identified, sterile leaves probably related to Polypodiaceae andseveral Cladophlebis-like (Osmundaceae?) ferns. In the continental Mata Amarilla Formation(lower Cenomanian), sterile fronds of Schizaeaceae (Anemioideae) are the main ferncomponent. This fact is consistent with the high abundance of cicatricose spores in theirpalynological assemblages. Extant Schizaeaceae are drought tolerant and grow in warm,sunny habitats and often seasonally dry conditions. The last is in accordance with the MataAmarilla Formation palaeosols, developed under marked seasonal rains and warm conditions.