Ediacaran-type vendotaenid macroalgae in an Ordovician Lagerstätte

Abundant noncalcified macroalgae with tubular, unbranching thalli are reported from the newly discovered Cabrières Biota of France, a Lagerstätte in the Landeyran Formation of the Montagne Noire, which represents Early Ordovician life in a polar region. Exceptional preservation of the thalli, which range in width from 0.08 mm to 1.00 mm and have a maximum observed length of 37 mm, involved a combination of kerogenization and pyritization. Their morphology is most similar to Vendotaenia, an alga known from the Proterozoic and Cambrian, but it is also possible that this simple morphology independently evolved in various algal lineages. Notably, these fossils demonstrate that the polar ocean of the Early Ordovician still hosted a morphologically simple algal community that more closely resembled floras of the Ediacaran and Cambrian than those of the later Ordovician.