Los tiburones Carcharhiniformes (Chondrichthyes, Galeomorphii) del Plioceno inferior de la Formación Arenas de Huelva, suroeste de la cuenca del Guadalquivir, Espa？a

carcharhiniform shark teeth from eight localities of the lower pliocene arenas de huelva formation were studied in the southwestern part of the guadalquivir basin. thirty-five samples were collected. three hundred kilograms of sediments were levigated and 48 teeth were found. the genera megascyliorhinus, premontreia, mustelus, paragaleus, carcharhinus and galeocerdo were recognized. carcharhinus diversity and abundance prevail followed by mustelus and premontreia, whereas the other taxons are scarce. the selachians asemblage points out to littoral-neritic, subtropical to temperate environments. carcharhiniform genera that have been found in the lower pliocene of the guadalquivir basin also were found in the upper miocene of the alvalade basin in portugal.