Lepidaspis, Dineley & Loeffler, 1976

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 : 557

Lepidaspis ? sp.

( Fig. 6D )

MATERIAL. — Specimen GIT 580-2: isolated tessera.

LOCALITY AND STRATIGRAPHIC HORIZON. — Same as specimens GIT 580-1, 3, 4, 6 and 7: locality (sample) 73, Tonnel’nyj Brook, south of De Long Strait, Chukotka; Lower Member (1) of Enmakaj Formation, Lochkovian.

DESCRIPTION ħe specimen is a diamond-shaped, 1.7 mm long tessera with a single central, narrow, elongate tubercle (c. 1.4 mm long). ħis tubercle has denticulated edges. Each denticulation is simple (undivided). Additionally, on each side of this central tubercle occurs a much smaller narrow tubercle ( Fig. 6D ). ħe base of the tessera is perforated by small foramina of the underlying (probably reticulated) layer. ħis tessera compares well with those of Lepidaspis serrata Dineley & Loeffler (1976 : figs 74, 76, pl. 32: 6, 7), and especially with the tessera in their plate 32: 6, which bears a small lateral tubercle beside the main central denticulated one. However, because we have here a single tessera, it is difficult to compare with the great variability of shapes observed on Lepidaspis serrata tesserae ( Dineley & Loeffler 1976), and so only tentatively assign GIT 580-2 to Lepidaspis .

Figures

FIG. 6. — Heterostracan microremains from the Lower Devonian of Chukotka,Arctic far-eastern Russia:A, B, Traquairaspididae? gen. et sp. indet., specimen GIT 580-5, from locality (sample) 73, Tonnel’nyj Brook, Lower Member (1) of Enmakaj Formation, Lochkovian; C, Traquairaspididae? gen. et sp. indet., specimen PIN 3845/2, locality 73-4 (74-3), Tonnel’nyj Brook, Lower Member (4) of Pil’hikaj Formation,Lochkovian; D, Lepidaspis? sp., tessera,specimen GIT 580-2,locality 73,same origin as specimen 580-5 (A, B); E, F, Oniscolepis? sp., tesserae, specimens GIT 580-1 (E) and 580-3 (F), locality 73, same origin as specimen 580-5 (A, B); G, H, Poraspididae gen. et sp. indet.,fragments of a scale (G) and of a plate (H), specimens GIT 580-4 (G) and 580-7 (H), locality 73, same origin as specimen 580-5 (A, B); I, Heterostraci? indet., tessera (platelet), specimen GIT 580-8, locality 73, same origin as specimen 580-5 (A, B). Scale bars: A, C, 1 mm; B, 100 µm; D, 300 µm; E, G, 500 µm; F, H, I, 200 µm.