Fossil seeds from the La Cantera Formation, Early Cretaceous, San Luis Province, Argentina

Abstract

In a study of fossil seeds recovered from the La Cantera Formation, Early Cretaceous, San Luis Basin, we establish a new species, Carpolithus volantus, and describe other specimens attributed to Carpolithus spp. and Ephedra canterata. The botanical affinity of winged seeds assigned to Carpolithus volantus is discussed in relation to the fossil flora recovered from this formation. Based on the abundance of Gnetales in the San Luis Basin (pollen grains, reproductive and vegetative structures assigned to Ephedra), we propose that Carpolithus volantus is affiliated with Gnetales (Weltwitschia). We suggest that Carpolithus spp. seeds may be angiospermous, because this group, represented by leaves and flowers, dominates the fossil macroflora of the La Cantera Formation. Micro- and macrofloral analyses of the La Cantera Formation and an assessment of available dispersal vectors suggests that wind (anemochory) and water (hydrochory) may have been the most important dispersal strategies for these seeds. The abundance and small size of seeds recovered from the La Cantera Formation, together with their morphological characters, such as the presence of wings in Carpolithus volantus, also favour abiotic mechanisms of dispersal such as anemochory or hydrochory.