Primitive Lycophytes record at the Rio Seco de los Castaños Formation, San Rafael Block, Mendoza Province, Argentina

MOREL, E.M., CINGOLANI, C.A., GANUZA, D., URIZ, N.J.

San Juan

Workshop; Devonian Land-sea interaction: evolution fo ecosystems and climate IGCP 499; 2007

Universidad Nacional de San Juan

In recent field works, we have found a small number of primitive plant debris at Río Seco de los Castaños Formation type section (Atuel Creek). They are fragmentary dichotomous small branches, 11 to 12 mm long and 0.5-0.7 mm wide. They present enations with a helicoidal phyllotaxis. These enations are 5 mm long and show expanded bases proximally decurrent, these corresponding to the surface ridging. Apices are usually truncated. All these primitive plants resemble the material described by Edwards et al. (2001, plate I, figs.6, 7, 8 & 9) for the Villavicencio Formation exposed at the San Isidro Creek, Mendoza Province. These fossil plants probably represent a new lycophyte taxon. The age could be Lower Devonian (Lochkovian-Pragian).