New genus of chondrichthyans from the Silurian - Devonian boundary deposits of Tuva (Russia)

• Autorzy: Zigaite Z.
• Konferencja: Evolution and Diversity of Chondrichthyans (2008 ; Warszawa)
• Języki publikacji: EN

Abstrakty

EN

A new genus of Chondrichthyes from the uppermost Silurian.lowermost Devonian deposits of central Tuva (Russia) is described on the basis of the microremains (scales). A sample from the Khondergei Formation of the Bazhyn-Alaak locality in the Tchadan region contained scales of a new chondrichthyan, Tuvalepis schultzei gen. et sp. nov., together with another chondrichthyan, Elegestolepis grossi KARATAJUTE-TALIMAA, 1973, as well as numerous scales of the thelodont Helenolepis navicularis KARATAJUTE-TALIMAA, 1978. The scales of T. schultzei display significant morphological variation and are characterized by a very fine, comparatively wide and flat crown with longitudinal ribs and a small and short neck. The growth pattern of T. schultzei scales is very different from that of elegestolepids described so far - the scales grew by appositional addition of layers towards the distal side of the crown, in contrast to the scales of Elegestolepis grossi which lack any kind of concentric growth lines.

Słowa kluczowe

EN

Chondrichthyans; Devonian; Elegestolepids; Silurian; Tuva

PL

devon; sylur; Tuwa

• Wydawca: Faculty of Geology of the University of Warsaw ; Komitet Nauk Geologicznych PAN
• Czasopismo: Acta Geologica Polonica
• Rocznik: 2008
• Tom: Vol. 58, no. 2
• Strony: 127--131
• Opis fizyczny: Bibliogr. 6 poz.,fot., rys.,

Twórcy

autor

Zigaite Z.

• University of Sciences and Technologies of Lille - 1, Laboratory of Palaeozoic Palaeontology and Palaeogeography, CNRS UMR 8014, F-59655 Villeneuve d'Ascq cedex, France,

Bibliografia

• JANVIER, PH. 1996. Early vertebrates. Oxford monographs on Geology and Geophysics, 393 pp. Clarendon Press; Oxford.
• KARATAJŪTĖ-TALIMAA, V. 1973. Elegestolepis grossi gen. et sp. nov., ein neuer Typ der Placoidschuppe aus demoberen Silur der Tuva. Palaeontographica, A 143, 35-50.
• KARATAJŪTĖ-TALIMAA, V. 1998. Determination Methods for the Exoskeletal Remains of early Vertebrates. Mitteilungen aus dem Museum für Naturkunde Berlin, Geowissenschaftliche Reihe, 1, 21-52.
• KARATAJŪTĖ-TALIMA A, V. & RATANOV, L.S. 2002. Distribution of vertebrates in Upper Ordovician–Lower Devonian of Tuva (Russia). In: J. SATKŪNAS & J. LAZAUSKIENĖ (Eds), Basin Stratigraphy – Modern Methods and Problems, The Fifth Baltic Stratigraphical Conference, Abstract Volime, pp 75-76, Vilnius.
• MÄRSS T., TURNER, S. & KARATAJŪTĖ-TALIMAA, V. 2007. Agnatha II –Thelodonti. In: H.-P. SCHULTZE (Ed.), Handbook of Palaeoichthyology. Vol. 1B, pp. 143.
• ØRVIG, T. 1977.Asurvey of odontodes (“dermal teeth”) from developmental, structural, functional and phyletic points of view. In: S.M. ANDREWS, R.S. MILES & A.D.WALKER (Eds), Problems in Vertebrate Evolution. Linnean Society Symposium Series 4, 53-75.