Oxfordian plug-shaped trace fossils from northwestern Algeria

Plug-shaped trace fossils B. perata, B. hemispherica, Bergaueria isp., Calycraterion samsonowiczi, Conostichus ornatus and Conostichus isp. are found in the middle-upper Oxfordian fine-grained sandstone of the Argiles de Saïda Formation (northwestern Algeria). Except for the trace Calycraterion which is interpreted as an annelid trace, these traces correspond to distinct behaviours of sea anemones, and their occurrence within tempestite deposits is influenced by a stress factors in a storm-dominated environment. The abundance of these plug-shaped trace fossils suggests that the upper Jurassic siliciclastic shelves with fine-grained soft clastic substrate were colonised by actinarian sessile benthos.