Schaubcylindrichnus formosus isp. nov. in Miocene Sandstones from Northeastern Taiwan

Abstract

Sheaves of smooth, thickly lined, vertically curved burrows occur abundantly in certain Tertiary strata in northern Taiwan. The burrows belong to the ichnogenus Schaubcylindrichnus, and they show several characteristics distinguishing them from previously established ichnospecies of this genus. The typical form in Taiwan is a sheaf converging into a crossing point in the lower part. This form is clearly different from the congruent sheaves and the loose bundles described for S. coronus and S. freyi, respectively. The observed Schaubcylindrichnus are significantly larger than other ichnospecies. The wide regional and stratigraphic spread of the ichnogenus Schaubcylindrichnus, together with the facies distribution ranging from shallow water to deep water settings and the distinct variation in morphology and size of the trace fossils motivate the proposition of a new species name, Schaubcylindrichnus formosus. The deposit feeder behavior proposed for other forms of Schaubcylindrichnus seems unlikely because of the successive, spreite-like overlap of burrows in the lower part of the system that would mean a repetitive exploitation of the same substrate. Schaubcylindrichnus formosus is interpreted as the work of a filter feeding worm living in offshore bar and shoreface environments.