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A new permineralized Equisetalean stem from Los Rastros Formation (Middle-Upper Triassic) from San Juan province, Argentina

2008; Museo Argentino de Ciencias Naturales Bernardino Rivadavia e Instituto Nacional de Investigación de las Ciencias Naturales; Linguagem: Inglês

10.22179/revmacn.10.294

1853-0400

Alexandra Crisafulli, Alicia I. Lutz,

Evolution and Paleontology Studies

A new permineralized Equisetalean stem from Los Rastros Formation (Middle-Upper Triassic) from San Juan province, Argentina. Several stems remains of a new genus and species belonging to the order Equisetales are described. They are represented by ribbed stems with distinct nodes and internodes, a pith with some sclerenchymatic cells and carinal canals. Wedge-shaped primary xylem and fascicular wedges of secondary xylem alternating with uniseriate rays are preserved. Comparison of these stems with other Equisetalean fossils from Gondwana is difficult because of their different kinds of preservation. There are only few records of permineralized Equisetalean stems from the Gondwana Triassic because the majority of data are derived from compression-impression fossils; however, one of them, Spaciinodum Osborn & Taylor, from Antarctica, is also based on a permineralization. The anatomical structure of the studied material suggests that it is a new taxon, as their features differ from all previously known species.