Caudicriodus serus ( Drygant, 1984 )

Drygant, Daniel & Szaniawski, Hubert, 2012, Lochkovian conodonts from Podolia, Ukraine, and their stratigraphic significance, Acta Palaeontologica Polonica 57 (4), pp. 833-861 : 850

Caudicriodus serus ( Drygant, 1984)

Figs. 9E , 11J–L.

1971 Icriodus postwoschmidti ; Mashkova 1971: pl. 3: 1 [non 8, 9].

1984 Icriodus serus sp. n.; Drygant 1984: 135, pl. 16: 27–29.

?2004 Latericriodus steinachensis (Al−Rawi eta morph Klapper and Johnson; Slavík and Hladil 2004: 144, pl. 1: 2 [only].

2010 Caudicriodus serus ; Drygant 2010: 62, pls. 3: 21, 4: 5, 8, 9, 11.

Material.—16 complete Pa elements from upper part of the Chortkiv Formation. Numbers of sections and samples: 4/8v, 11/4, 11A/6, 7, 9, 11B/1, 11/ 375 m.

Remarks.—Pa elements of this species characterize short and wide platform, short postero−lateral process, diversification of the elements into “right” and “left” elements differing in morphology of platform and spindle. The platform gets wide behind the fourth transverse ridge and is the widest approximately opposite the second transverse ridge. Outer bord of platform in all elements slighty curved. Spur of the “right” elements not developed, inner border of the platform bowed. Spur of the “left” elements short, triangular and less edged. Spindle straight or slightly curved, elongated (0.8–1.0 mm), with 4–6 transverse ridges. The transverse ridges in some forms slightly flattened, the denticles of the lateral rows have circular base and are less thicker than denticles of median row. Denticles of median row joined by thin margins with themselves and with lateral denticles. Postero−lateral process short, triangular, with rare and small denticles. Angle between the median row and postero−lateral processes about 95–110 °. Primary cusp bigger and higher than the secondary.

Caudicriodus serus differs from related Caudicriodus postwoschmidti (Mashkova, 1968) by the outline of platform, curved spindle and lesser angle between the median row and postero−lateral process ( Fig. 9D, E ).

Outline of the platform in our specimens is closest to the specimen from the Lower Pragian of Spain, illustrated by Carls (1969: pl. 3: 10) as representative of his new subspecies Icriodus angustoides castilianus Carls, 1969 . It differs from the typical specimens of the subspecies, as well as from the Caudicriodus serus by a bigger number and density of the transverse ridges and by a gradual reduction of the spindle width, anteriorly and posteriorly from its middle.

The specimen described by Slavík and Hladil (2004: 144, pl. 1: 2) as the “ Latericriodus steinachensis ( Al−Rawi, 1977) eta morph Klapper and Johnson” differs from the species by straight spindle and triangular postero−lateral process with undenticulated edge. In our opinion its morphology is closest to Caudicriodus serus .

Stratigraphic and geographic range.— Caudicriodus serus Zone (middle–upper Lochkovian) in Podolia and probably the uppermost Lochkovian in Barrandian.

Figures

Fig. 9. Ontogenetic development and morphological comparison of Pa elements of Podolian Caudicriodus species.