Article: The Lower Cambrian trilobite Bigotina and allied genera

The Lower Cambrian genus Bigotina is reinvestigated on the basis of new material (including larval stages and pygidia) from the type locality of B. bivallata, from the upper third of the Saint-Jean-de-la-Riviere Formation (Carteret, Normandy, France). A neotype for B. bivallata is proposed. The new material clarifies the generic concept of this very early trilobite which exemplifies the primitive morphology of non-olenellid trilobites. The taxonomic position of Bigotina is discussed in comparison with early redlichiids (Pararedlichiinae, Wutingaspinae and Abadiellidae) and some ellipsocephalids; at present Bigotinidae are placed in the superfamily Redlichiacea, and the relationship to ellipsocephalids is discussed. The occurrence of B. bivallata and related taxa in Western Europe, Morocco and Siberia is of significance for correlation and palaeogeography during Early to Middle Atdabanian time.