Trace fossils from the Permian Teresina Formation at Cerro Caveiras (S Brazil)

The ichnofauna of the Teresina Formation from the Cerro Caveiras (Dom Pedrito, Rio Grande do Sul State,South Brazil) is revised in this paper. Bergaueria isp., Cochlichnus cf. anguineus, Cruziana problematica, cf. Diplocraterion isp., Diplopodichnus biformis, Helminthopsis isp., Lockeia siliquaria, Multina arcuata isp. nov., Oldhamia isp., Palaeophycus striatus, P. tubularis, Phymatoderma burkei, Planolites beverleyensis, P. montanus, Teichichnus isp., and Thalassinoides isp. were recorded. Isopodichnus problematicus, Helminthopsis tenuis and Unarites isp., previously described in these deposits are now described as Cruziana problematica, indeterminate molluscan trail, and Multina arcuata isp. nov., respectively. The ichnofauna is composed chiefly of horizontal, simple shallow burrows, with a predominance of feeding structures. Resting, dwelling and crawling structures also occur, as well as indeterminate tiny grazing trails, but are less frequent. Ichnodiversity and intensity of bioturbation are usually low, and P. montanus is the commonest ichnotaxon. The main characteristics of the ichnofauna suggest a marine benthic fauna stressed by salinity fluctuations and resulting in an impoverished Cruziana ichnofacies. The absence of vertical burrows and the common occurrences of monospecific assemblages of Planolites indicate extreme stress events, probably due to the establishment of freshwater conditions. Further studies focused on the ichnological signatures of these deposits will provide more detailed information to improve the current paleoecologic and paleoenvironmental interpretations of the Teresina Formation deposits.