Paleoecological characterization of ostracods in beachrocks from the Northern sector of the Rio Grande do Sul Coastal Plain, Brazil

A micropaleontological analysis on 15 beachrock samples from the Northern sector of Rio Grande do Sul Coastal Plain (RSCP ), southern Brazil , revealed a relatively diverse and well-preserved ostracod assemblage composed of 16 species , including Cyprideis multidentata Hartmann, Callistocythere nucleoperiscum Whatley et al., Cytheretta punctata Sanguinetti, Caudites ohmerti Coimbra & Ornellas , and Argenticytheretta levipunctata Sanguinetti et al. Eleven ostracod species are left in open nomenclature or tentatively identified . Besides ostracods , some foraminifers , echinoderm spines, and fish remains (teeth) were also recovered ; however , the scarcity of specimens or poor preservation precluded identification at species level. Based on the Ostracoda taxonomic composition it is proposed that the beachrocks characterize environmentally condensed assemblages . This preliminary study reveals the importance and potentiality of micropaleontology for understanding the processes involved in the formation of beachrocks. Keywords: Pelotas Basin, Quaternary, coastal environments, micropaleontology, taphonomy.