First record of clathropteris brongniart in the late triassic of gondwana

Abstract

Impressions fronds of Dipteridaceae found in the upper part of the Paso Flores Formation (Norian), Cañadón de Pancho area, Neuquén Province, Argentina are described. In this Formation, the species Dictyophyllum tenuifolium (Stipanicic and Bonetti) Bonetti and Herbst, 1964 and Dictyophyllum (Thaumatopteris) rothi(Stipanicic and Bonetti) Bonetti and Herbst, 1964 have been previously recorded. The frond fragments found show a coalescent lamina at the base, and primary segments with simple secondary veins, parallel and perpendicular to the primary vein and crossed by tertiary veins, forming a meshwork of regular orthogonal areoles. These characters are diagnostic of Clathropteris Brongniart, 1828 which distinguishes it from other fossil genera of this fern family of Gleicheniales. Specific identification is difficult due to the high morphological variability of fronds present in the different species of the genus. So far, Clathropteris is recorded in the Triassic and Jurassic strata of the Northern Hemisphere and in Jurassic deposits in the Southern Hemisphere. Although the analyzed specimens are incomplete, the importance of this record in the Paso Flores Formation of Argentina lies in the fact that the spatial and temporal distribution of the genus is broadened because it represents the first record of Clathropteris for the Late Triassic of Gondwana.