Data from: Three-dimensional preservation of cellular and subcellular structures reveal 1.6 billion-year-old probable crown-group red algae

The ~1.6 Ga Tirohan Dolomite of the Lower Vindhyan in central India
contains phosphatized stromatolitic microbialites. We report from there
uniquely well-preserved fossils interpreted as crown-group rhodophytes
(red algae). The filamentous form Rafatazmia chitrakootensis n.gen, n.sp.
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 represent pit connections and pit plugs. Another
filamentous form, Denaricion mendax n.gen., n.sp., has coin-like cells
reminiscent of those in large sulfur-oxidizing bacteria, but much more
recalcitrant than the liquid-vacuole-filled cells of the latter. Its wider
affinities are uncertain. Ramathallus lobatus n.gen., n.sp. is a lobate
sessile alga with pseudoparenchymatous thallus and apparent tetraspore
formation, suggesting florideophycean affinity. Rafatazmia and Ramathallus
are interpreted as crown-group multicellular rhodophytes, antedating the
oldest previously accepted red alga in the fossil record by about 400
million years.