Spore-like bodies in some Early Paleozoic acritarchs: clues to chlorococcalean affinities

We present discoveries of internal bodies in problematic Silurian and Devonian organic−walled microfossils classified traditionally as polygonomorph, acanthomorph, sphaeromorph, and herkomorph acritarchs. These bodies are comparable with reproductive structures (autoand/or aplanospores) of modern unicellular green algae (Chlorococcales). Our findings suggest that many of these microfossils may represent asexually reproducing (sporulating) vegetative cells of chlorococcalean algae. The presence of spore−like bodies in the studied acritarchs supports earlier suggestions, based on ultrastructural and biomarker studies, that some acritarchs can be affined with green algae.