Flora and insect trace fossils from the Mio-Pliocene Quebrada del Toro locality (Gobernador Solá, Salta, Argentina)

Abstract

Foliar impressions were recorded for the first time in the Mio-Pliocene lacustrine sediments at the Quebrada del Toro outcrop (Salta, Argentina). Here we describe a horsetail (Equisetum cf. giganteum L.), ferns (Pteris cf. deflexa Link., Pteris cf. plumula Desv., Circinites pteridoides nov. gen. et nov. sp.) and monocotyledons (Typha cf. latifolia L., Scirpites sp., Poacites sp., Rhizomatites cyperoides nov. gen. et nov. sp., Schoenoplectus californicus, Cyperocarpus sp. 1, Cyperocarpus sp. 2 and Cyperocarpus sp. 3). A few impressions contain insect traces, which correspond with marginal (Phagophytichnus regularis Vasilenko and Phagophytichnus ekowskii van Amerom), non-marginal excisions (Folifenestra polylobata nov. isp.) and piercing and sucking (Circulifolites concavus nov. igen et nov. isp). The inferred paleoenvironment reflects a flora related with water bodies surrounded by open terrestrial areas and limited by a forest. Based on the sedimentological context and plant community composition, we conclude that the plant fossils preserved at the Quebrada del Toro outcrop were deposited in a lagoon environment, comparable to a reed bed. Similar Mio-Pliocene deposits in Northern Argentina were found at the Palo Pintado Formation (Salta, Argentina). The sedimentological characteristics and the paleofloristic similitudes between the Quebrada del Toro outcrop and Palo Pintado Formation support the age assigned to the first fossiliferous location.