Malacostráceos da formação Manacapuru (Siluro-Devoniano) da bacia do Amazonas, Estado do Pará, Brasil

Abstract

This work deals the systematic and paleobiologic studies on malacostraca siluro-devonian in two outcrops of the Manacapuru Formation, located at Belo Monte site, Pará state, Amazonas Basin. Were identified the taxa Paranebalidae indet. A and Paranebalidae indet. B, phyllocarids, as well as Stenasellidae indet. isopod. During the siluro-devonian times these malacostraceans were very rich and diverse, cosmopolitan, lived in all marine regions and common elements of the benthic life. The specimens had robust and articulated carapaces with fragmentation and abrasion low grades that suggest low energy during the burial and less time of permanence in the taphonomic active zone. The pleopods and uropod articulated in Stenasellidae indet. and the exopodit and pleonite articulated with the pleopod in Paraneballidae indet. B suggest stronger articulations or fast burial and catastrophic death of these elements of biocoenosis. The isolated exopodite of Paraneballidae indet. A reveals weaker articulations among the others epipodites and exopodites, as well as short distance transport before the final burial, due the preservation of delicate spines of posterior margin and therefore considered as an element of thanatocoenosis. The pattern of the fossiliferous record may be related to siliciclastic sediments in the rocks of Manacapuru Formation, which does not lead to accumulation of animals with poorly mineralized body.