Zemes un vides zinātnes Earth and Environment Sciences - Latvijas ...
Zemes un vides zinātnes Earth and Environment Sciences - Latvijas ...
Zemes un vides zinātnes Earth and Environment Sciences - Latvijas ...
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66 ADVANCES IN PALAEOICHTHYOLOGY<br />
Lophosteus connexus Märss, 1986<br />
Fig. 4<br />
1986 Lophosteus? connexus n. sp. — Märss: 59, 90; pl. 34, figs 7-11.<br />
1997 Lophosteus? connexus — Märss: 35; fig. 8.<br />
2000 Lophosteus? connexus — Märss: 68.<br />
Holotype: scale GIT 232-413 (= Pi 7042; Märss 1986: pl. 34, fig. 10).<br />
Additional material: 15 scales <strong>and</strong> plates.<br />
Type locality: Vaivere outcrop, Saaremaa, Estonia.<br />
Type horizon: lowermost part of Äigu Beds, Ozarkodina remscheidensis<br />
eosteinhornensis Conodont Subzone (Viira <strong>and</strong> Männik 1997), Kaugatuma Regional<br />
Stage, Pridoli, Upper Silurian.<br />
Localities: Äigu, Saaremaa, Estonia; the following bore holes in Estonia: Ohesaare,<br />
depth 64.65 m, <strong>and</strong> in Latvia: Kolka-54, depth 261.3-261.5 m; <strong>and</strong> north bank of<br />
Mikhailovsk Pond, Ufa amphitheatre, western slope of Central Urals, Russia.<br />
Emended diagnosis: small scales (up to 1.5 mm deep <strong>and</strong> 0.3 mm long), curved <strong>and</strong><br />
straight dentine ridges ending posteriorly in a pointed tip <strong>and</strong> reaching the posterior<br />
margin of the scale or beyond. The ridges carry very oblique, short, lateral ridgelets<br />
angled at 20° or less to the crest. The ridges have a narrow, smooth <strong>and</strong> flat crest. The<br />
posterior-most pair of ridgelets form a wider, flattened, wing-like structure.<br />
Description: Märss (1986) figured five specimens <strong>and</strong> chose an elongated low scale as<br />
the holotype (Märss 1986: pl. 34, fig. 10). Specimen GIT 232-412 (Märss 1986: pl.<br />
34, fig. 8) represents a typical scale (Fig. 4 A, B) with broad, dorsally overlapped area<br />
(“peg”); the scale has a weakly developed keel on the inner side. Vascular canals open<br />
as pores aro<strong>un</strong>d the ridges as in L. superbus. A median ridge scale (probably from the<br />
dorsal midline) is shown in figure 11 (Märss 1986: pl. 34). Specimen GIT 232-415<br />
(Märss 1986: pl. 34, fig. 9) looks like a scale, but it is a plate with a convex posterior<br />
border <strong>and</strong> a flat inner surface; it carries the typical ridges with oblique ridgelets <strong>and</strong> a<br />
wing-like posterior-most pair of ridgelets.<br />
Fig. 4. Lophosteus connexus; Pridoli, Upper Silurian; Vaivere outcrop, Saaremaa, Estonia.<br />
A, scale GIT 232-412; B, detail of A. SEM pictures, scale bars equal 100 µm.