Reconstruction of Proterocladus antiquus （Courtesy of Dinghua Yang ） Age Late Mesoproterozoic ~1,000 Ma Taxonomy Kingdom: Plantae Phylum: Chlorophyta Class: Ulvophyceae Order: Siphonocladales Family: Siphonocladaceae Genus: Proterocladus Species: Proterocladus antiquus Morphological description Proterocladus antiquus is characterized by a branched thallus composed of uniseriate filaments. The organism ranges from approximately 0.3 to 3.3 mm in height and 0.1 to 2.4 mm in wid