Resumen de Un nuevo tallo permineralizado de Equisetales de la Formación Los Rastros (Triásico Medio - Superior), provincia de San Juan, Argentina
Alexandra María Cristina Crisafulli, Alicia Isabel Lutz
A new permineralized Equisetalean stem from Los Rastros Formation (Middle-UpperTriassic) from San Juan province, Argentina. Several stems remains of a new genus and species belonging tothe order Equisetales are described. They are represented by ribbed stems with distinct nodes and internodes, apith with some sclerenchymatic cells and carinal canals. Wedge-shaped primary xylem and fascicular wedges ofsecondary xylem alternating with uniseriate rays are preserved. Comparison of these stems with other Equisetaleanfossils from Gondwana is difficult because of their different kinds of preservation. There are only few records ofpermineralized Equisetalean stems from the Gondwana Triassic because the majority of data are derived fromcompression-impression fossils; however, one of them, Spaciinodum Osborn & Taylor, from Antarctica, is alsobased on a permineralization. The anatomical structure of the studied material suggests that it is a new taxon, astheir features differ from all previously known species.
