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Eoembryophytic An epoch in the evolution of plants, proposed in 1993 by J. Gray, that lasted from the early Llanvirn (about 476Ma) in the middle Ordovician to the late Llandovery (about 432 Ma) in the Early Silurian. Fossil tetrads comprising four spores bound by a membrane make their first appearance during this epoch and occur over a wide geographic range.