CROWN-GROUP RHODOPHYTES IN THE LATE PALAEOPROTEROZOIC (CA. 1.6 GA)

The late Palaeoproterozoic (ca. 1.6 Ga) Tirohan Dolomite of the Lower Vindhyan in central India contains phosphatized stromatolitic microbialites. We report from there uniquely well-preserved fossils that may be interpreted as crown-group eukaryotes, specifically rhodophytes (red algae). A filamentous form has uniserial rows of large cells and grows through diffusely distributed septation. Each cell has a centrally suspended, conspicuous rhomboidal disk interpreted as a pyrenoid. The septa between the cells have central structures that may possibly represent pit connections and pit plugs. A fleshy lobate form has pseudoparenchymatous thallus and tetraspore formation. The fossils are interpreted as crown-group rhodophytes representing bangiophycean and florideophycean branches, respectively, which considerably pushes back the origin of the red algae as currently understood.