Among dinoflagellates, extant cladopyxidaceans may provide a missing link to better understand the first evolutionary transformations from ancestral configurations towards the more abundant and more derived patterns in Gonyaulacales and Peridiniales. A restudy of the extant, motile-defined Micracanthodinium setiferum from plankton samples from the Indian and Atlantic Oceans and Mediterranean Sea demonstrates that the correct plate formula is Po Pt X 3′+*4′ 4a 7′′ 7C 4S? 6′′′ 0p 2′′′′. A ventral pore is found between 1′, 3′ and *4′. A restudy of the extinct, fossil-defined Cladopyxidium saeptum from the upper Paleocene of Delaware (U.S.A), demonstrated the presence of an identical tabulation. A ventral pore (=porichnion) was positioned between *1′ and 7′′. Cladopyxidium is morphologically closer to Micracanthodinium than to Cladopyxis. However, since Cladopyxidium has been extinct since the middle Eocene it is unlikely that Micracanthodinium and Cladopyxidium will have a direct biological link; the close morphological link between both does suggest an important phylogenetic relationship between both in the evolution of cladopyxidaceans.