Algas fósiles del sitio paleontológico La Gallina en El Salvador

Abstract

In 2015, a prospecting excavation was carried out due to the development of the San Miguel bypass. In this inspection the ravine called La Gallina was discovered in which the stratigraphy of the area is exposed, formed by a horizon bearing vegetable imprints in a shale matrix. The imprints host fragments of wood and twigs; in addition to leaves and seaweed. The paleontological site in question is located 600 meters from the main road that leads to the Department of La Unión, between 13 ° 26’56.10 “LN and 88 ° 6’46.98” LO. The floor bearing the imprints has a thickness of 1.20 meters and is constituted by whitish laminated shales and belongs to the member c1´l of the Cuscatlán Formation and Pleistocene age. The random way in which the fossils were found, the lack of evidence to determine the event responsible for the sedimentation of the body of water and the discovery that most of the algae imprints correspond to marine forms, represent an important challenge for the study about this imprints. The main objective was to determine the lowest possible taxon to which belong the algae found. The determination was consists in examining under the light of a binocular stereo microscope and high magnification magnifier, twenty-four seaweed imprints, to which they were make morphometric measurements and taxonomic identification character analysis that allow to be contrasted with the presented by the genera of current algae. The study determined that ten imprints belonged to green algae, of the genus aff. CodiumCodium, aff. , RhizocloniumRhizoclonium, , aff. CladophoraCladophora, aff. , NitellaNitella and aff. CladophoropsisCladophoropsis Twelve imprints corresponds to aff DictyotaDictyota a brown seaweed and two imprints have characteristics of red algae, of the order Gracilariales. By the type of algal flora found it can be inferred that in ancient times the paleontological site La Gallina was influenced by sea or brackish water. The information generated, will allow reconstruct the geological history of the area and the prevailing climatic conditions over a million years ago in the country.