Distribution of Devonian Phoebodontid Fishes and Renewed Zonation for the Givetian-Famennian

The genus Phoebodus is the most numerous of the known genera among the Devonian chondrichthyans, and includes 13 species: Ph. bifurcatus Ginter and Ivanov; Ph. curvatus Ivanov; Ph. depressus Ginter, Hairapandian and Klug; Ph. fastigatus Ginter and Ivanov; Ph. gothicus Ginter; Ph. latusGinter and Ivanov; Ph. limpidus Ginter; Ph. politus Newberry; Ph. rayi Ginter and Turner; Ph. saidselachusFrey, Coates, Ginter, Hairapandian, Rücklin, Jerjen and Klug; Ph. sophiae St. John and Worthen; Ph. turneraeGinter and Ivanov; Ph. typicus Ginter and Ivanov. The species Phoebodus bifurcatus, Ph. fastigatus, Ph. gothicus, Ph. latus, Ph. limpidus, Ph. sophiae, Ph. turnerae, and Ph. typicus are cosmopolitans, and occur in many regions of the world. The endemic species Ph. depressus, Ph. politus and Ph. saidselachus appeared in the Middle and Late Famennian. Six phoebodontid zones were proposed for the Givetian-Famennian based on the distribution of Phoebodusspecies (Ginter and Ivanov, 1995). The sophiae phoebodontid Zone according to previous version of zonation was corresponded to an interval of the Middle varcus–Lower hassi conodont zones (CZ) of the Givetian and Frasnian; the latus Zone – to the Upper hassi–jamieae CZ of the Frasnian, the bifurcatus Zone – to the rhenana–linguiformis CZ of the Frasnian. In the Famennian, the typicus phoebodontid Zone was correlated with the Upper triangularis–Upper rhomboidea CZ, the gothicus Zone – with the Lower marginifera–Upper postera CZ, and the limpidus Zone – to the Lower expansa–Middle praesulcata CZ. There were no data on the distribution of phoebodontid species in the interval of the Lower–Middle triangularis CZ. Many new data on the occurrence of Phoebodus zonal species outside their previously known stratigraphic intervals appeared recently. The various species of Phoebodus occur in the North Timan, Middle Urals, Kuznetsk Basin in Russia, Australia, Armenia, Belarus, Iran, and others. A new data on the distribution of species in the Pokrovskoe section in the Middle Urals, Russia allow to update the boundary between the Phoebodus sophiae and Ph. latus phoebodontid zones. Ph. typicus was recorded in the Lower and Middle triangularis CZ of the Kuznetsk Basin, Siberia, Russia. Ph. gothicus was reported from the Lower crepida in Iran and Morocco (Ginter et al., 2002; Hairapetian and Ginter, 2009). Ph. limpidus Ginter was found in the Uppermost marginifera–Lower praesulcata CZ in the Carnic Alps (Randon et al., 2007). The bifurcatus Zone remained only unchanged in the result of revision of zone ranges. The ranges of five previously established phoebodontid zones are revised and emended. The Phoebodus sophiae Zone corresponds to the Lower Po.timorensis–P.dengleri dengleri CZ; the Ph. latus Zone – to the S.norrisi–Pa.jamieae CZ; the Ph.bifurcatus Zone – to the Pa.jamieae–Pa.ultima CZ. The Ph. typicus Zone was correlated with the Pa. subperlobata– Pa.minuta minuta CZ, the Ph. gothicus Zone – the Pa.crepida crepida–Pa.marginiferautahensisCZ, and the Ph. limpidus Zone – the Sc. velifer velifer–S. (E.) praesulcataCZ.