Abstract

OTTONE, Eduardo G.. Triassic plants from the Rincón Blanco Group, San Juan Province, Argentina. Ameghiniana [online]. 2006, vol.43, n.2, pp.477-486. ISSN 1851-8044.

Fluvial and lacustrine strata of the Portezuelo and Casa de Piedra Formations, Rincón Blanco Group, Middle to Upper Triassic of San Juan province, yield a distinctive taphoflora. The Portezuelo Formation plant remains are relatively scarce and mostly include peltasperms (Lepidopteris madagascariensis Carpentier and Antevsia sp.), together with Bennettitales (Taeniopteris sp.), and probable Coniferales (Incertae sedis (ovule scale?) sp. B) and pteridosperm fronds (Incertae sedis sp. A). The fossil plant assemblage recovered from the Casa de Piedra Formation is more abundant and mainly includes Corystospermales (Dicroidium incisum (Du Toit) Anderson and Anderson, D. odontopteroides var. moltense Retallack, D. odontopteroides var. obtusifolium Johnston, D. odontopteroides var. remotum (Szajnocha) Retallack, Xylopteris densifolia (Du Toit) Frenguelli, X. remotipinnulia (Anderson and Anderson) comb. nov., X. rigida (Dun) Jain and Delevoyras, X. spinifolia (Tenison-Woods) Frenguelli and Zuberia zuberi (Szajnocha) Frenguelli, but also Sphenophyta (Neocalamites sp.) and Cycadales (Pseudoctenis sp. A and P. sp. B). The flora of the Rincón Blanco Group would chiefly represent a substratum of herbaceous and shrubby vegetation. Although the Portezuelo and Casa de Piedra Formations have been referred to the Cortaderitian and Florian stages, on the basis of regional correlations, the lack of diagnostic taxa difficult close comparisons of the Rincón Blanco Group flora with local biozones.

Keywords : Argentina; Triassic; Plants; Systematics.