Trace fossils Didymaulichnus cf. tirasensis and Monomorphichnus isp. from the Estonian Lower Cambrian, with a discussion on the early Cambrian ichnocoenoses of Baltica

The bilobed trace fossil Didymaulichnus cf. tirasensis Palij in the Lower Cambrian Voosi Formation of western Estonia adds to the small number of pre-trilobite Cambrian trace fossils identified from Estonia. A possible earliest Cambrian Baltica trace fossil province, including trace fossils with an undulating bilobed and three-lobed lower surface, of which D. tirasensis is an example, is proposed. In Baltica traces of this type occur also in the Ukraine and northern Scandinavia. In each occurrence they are associated with vertical spiral traces and precede the local first appearance of arthropod-type trace fossils. The earliest Estonian arthropod-type trace fossil, Monomorphichnus isp., described here from the Sõru Formation, belongs to the trilobite-bearing Lower Cambrian.