ABSTRACT
One of the most difficult problems in evolutionary paleontology is the almost sudden appearance of multicellular animals (Metazoa) at and near the beginning of the Cambrian period, commonly epitomized as the “Cambrian Explosion.” This phenomenon is in conflict not only with the notion that evolution is a slow process that proceeds only in small steps. Today we also know from molecular data that animal phyla must have originated much earlier. What do we know about life before this event?
