Turinia sp.

Mark-Kurik, Elga, Blieck, Alain, Burrow, Carole J. & Turner, Susan, 2013, Early Devonian fishes from coastal De Long Strait, central Chukotka, Arctic Russia, Geodiversitas 35 (3), pp. 545-578 : 560-561

Turinia sp.

( Fig. 7F )

MATERIAL. — Specimen GIT 580-12: broken scale.

LOCALITY AND STRATIGRAPHIC HORIZON. — Locality (sample) 73, Tonnel’nyj Brook, south of De Long Strait , Chukotka ; Lower Member (1) of Enmakaj Formation, Lochkovian .

DESCRIPTION ħis relatively large scale, seen in dorsal crown view, is broken on either side of the crown. All that remains is the wide and flat elliptical mid-section of the crown and the anterior parts of two lateral segments, which may or may not have been separated from the mid-section by a deep channel on the one side. ħe remnants of an expanding lateral lappet are left mid-scale on the other side. ħe neck is trough-like and the base apparently not deep.

ħis specimen shows a typical turiniid body scale configuration, resembling the type species. It also resembles the mid-section of body scales of other turiniid taxa such as Turinia barentsia from the Ben Nevis Formation, Red Bay Group of Spitsbergen ( Blom & Goujet 2002), and Turinia composita , but with the poor state of preservation, this taxon is left in open nomenclature.

Family NIKOLIVIIDAE Karatajūtė-Talimaa, 1978 ? Genus Nikolivia Karatajūtė-Talimaa, 1978 ?

Nikolivia ? sp. cf. N. gutta

Karatajūtė-Talimaa, 1978

( Fig. 7G, H )

MATERIAL. — Specimen GIT 580-13: scale.

LOCALITY AND STRATIGRAPHIC HORIZON. —Locality (sample) 73,Tonnel’nyj Brook, south of De Long Strait , Chukotka ; Lower Member (1) of Enmakaj Formation, Lochkovian .

DESCRIPTION

GIT 580-13 has a flat simple slightly subtriangular crown with a slight scalloping of anterior rim ( Fig. 7G ) and a shallow neck that merges with the rounded base that almost matches the crown in size. ħe ventral view shows the wide open, thelodontid type narrow base, which is a relatively thickened torus around a very large pulp cavity with some dental tubule openings within ( Fig. 7H ).

Based on published occurrences,there are no exactly similar scales to this one from the Chukotka material or elsewhere. However, it is a placoid thelodont scale rather than a simple shark scale based on its rounded base and simple crown. It is not identical to but is generally comparable with those of Nikolivia gutta , known from several Lower Devonian (Lochkovian) assemblages, but shares the large open pulp cavity and smooth subrounded crown shape (cf. Turner 1973: pl. 1; Karatajūtė-Talimaa 1978). ħe range of variation of another rounded nikoliviid scale with a large rounded base, Nikolivia aligera Karatajūtė-Talimaa, 2002 (Karatajūtė-Talimaa2002:fig.6) also from Arctic Russia, might also encompass this scale. Within the postulated scale range of yet another taxon, Nikolivia balabayi Karatajūtė-Talimaa,1978 (Karatajūtė-Talimaa 1978: fig. 29; see also Märss et al. 2007: fig. 128) from the Lower Devonian Czortkow Stage of Podolia ( Ukraine), there are some smooth scales of a similar nature but they are more elongate.

Figures

FIG. 7.— Thelodont scales from the Lower Devonian of Chukotka,Arctic far-eastern Russia:A, B, Turinia pagei (Powrie,1870)?,specimens GIT 580-19 (A in antero-lateral view) and 580-16 (B in lateral view); C, D, Turinia sp. cf. T. composita Karatajūtė-Talimaa, 2002,specimens GIT 580-10 (C in crown view) and 580-11 (D in latero-crown view); E, Turinia sp. cf. T. polita Karatajūtė-Talimaa,1978, specimen GIT 580- 17 in lateral view; F, Turinia sp., specimen GIT 580-12 in crown view; G, H, Nikolivia? sp. cf. N. gutta Karatajūtė-Talimaa,1978, specimen GIT 580-13 in crown (G) and basal (H) views;I-K, Nikolivia? sp., specimen GIT 580-9 in basal (I), crown (J) and latero-crown (K) views. All specimens from locality (sample) 73,Tonnel’nyj Brook,Lower Member (1) of Enmakaj Formation,Lochkovian.Scale bars:A-C,F,G, 200 µm; D, 250 µm; E, 300 µm; H-K, 100 µm.