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Based on new detailed mappings of the Mani Peninsula and the Taygetos Mountains (Greece) a new stratigraphic and tectonic subdivision of the two basal tectonic units of the external Hellenides, the "Plattenkalk-Series" and the "Phyllite-Quartzite-Unit" was achieved. Instead of the misleading "Plattenkalk-Series" the new term "Taygetos Group" is introduced in accordance with the rules of the "International Stratigraphic Guide". At the base the Taygetos Group begins with the fossil-free metaclastites of the Kastania Formation. They are overlain by the dolomitic marbles of the Skamnaki Formation. Cherty limestones of the Yerma (Germa) Formation yielded jurassic ammonites and were followed by vary-coloured and banded marbles of the Elea Formation. The carbonate sequence comprises the fossil-proven timespan from Late Triassic to Eocene. The stratigraphic sequence of the Taygetos Group is ending with the carbonaceous metaclastites of the Vathia Formation. Trace fossils, olistholiths and fauna indicate deepwater conditions during Oligocene. The minimum total thickness of the Taygetos Group is 1400 m, but the base of the group is not exposed. That the original, now tectonically overprinted contact between Kastania and Skamnaki Formation is primarily of sedimentary origin is indicated a typical sequence and transitions between the two formations. The differential subsidence of the Taygetos carbonate platform and the fragmentation of the sediment basin into horst and graben structures has led, beginning in early Liassic, to different lithologies of the carbonates and to changing thicknesses on the inner and outer Mani peninsula. With appearance of biotite and chloritoid the degree of metamorphic overprinting of the Taygetos Group can be determined as "low grade". The sequence of the Taygetos Group is tectonically overlain by the Phyllite-Ouartzite-Unit s.l. consisting of several subunits which differ in degree of metamorphosis and lithological composition. The Tyros Formation and the variscan gneisses on Crete are not part of the Phyllite-Quartzite-Unit s.str. but are considered to be the original basement of the Tripolitza Unit. A detailed comparison after the literature and own investigations is made between the two lowermost tectonic units of the external Hellenides, the Plattenkalk Unit of the Peloponnese and the Talea Ori Group of Crete and also between the different subunits of the Phyllite-Quartzite-Series. Distinct differences can be noted but also many common properties concerning stratigraphic sequence, metamorphism and tectonics are obvious. The Telea Ori Group of Crete shows many similarities with the Mesozoic to Early Tertiary sedimentary sequence of the Taygetos Group. But the Paleozoic of the Talea Ori Groups of Crete differs considerably from the Kastania Formation of the Peloponnese, its probable fossil-free equivalent. The variscan crystalline and the Tyros Formation (Ph.Qu.S. s.l.) are considered to be the basal part of the Tripolitza thrust sheet, they are not part of the Phyllite-Quartzite-Series s.str. A variscan crystalline on the Peloponnese still needs confirmation. The Phyllite-Quartzite Unit s.str. of Crete and the Peloponnese developed tectonic subunits and mostly HP/LT metamorphism. While parts of the Phyllite-Quartzite-Series s.str. of Crete are dated stratigraphically by fossils, no stratigraphic dating free of doubts is presently known from the Peloponnese. Finally some of the tectonic and palinspastic ideas about origin, paleogeographic position and metamorphic development of the Taygetos Group and the Phyllite-Quartzite-Series of Crete and the Peloponnese are discussed and a model of the geodynamic development of the External Hellenides is presented.