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ADVANCES IN PALAEOICHTHYOLOGY
Nostolepis cf. amplifica
Fig. 4 A-M
2003 b Nostolepis amplifica; Valiukevicius, figs 2 A-H, 3 A-I.
Range. The lower part of the Šilale Beds of the Minija Formation, Pridoli, Upper
Silurian.
Material. 72 flank scales.
Remarks. N. amplifica was originally defined on large trunk scales having a high robust
median crown area ornamented with two to six short parallel ridges fading out at a
quarter of crown length, and narrow lateral crown steps delimited by clear oblique neck
ridges. Most of the Lužni scales are within the morphologic range of N. amplifica,
differing only in having more pronounced, wider bases protruding beyond the anterolateral
edges of crowns, and scales generally being smaller (crowns 0.35-0.6 mm long
and 0.3-0.85 mm wide). Two reasons preclude definite assignment of the scales to N.
amplifica. First, the long stratigraphic gap that separates the isolated occurrence (338.6
m) of N. cf. amplifica from the range of definite N. amplifica (202.4-172.2 m); and
second, histologic differences. The Stranggewebe in crowns of N. amplifica is covered
by a mantle of highly cellular simple mesodentine and is distinguished by short and
narrow Stranglacunae; osteocytes are present in the primordial lamella only; large
principal vascular canals develop in each growth lamella (Valiukevicius 2003 b, fig. 3
A-I). These characters are almost opposite in the Lužni scales. The enveloping
Stranggewebe mantle of the networked mesodentine is absent here or is very thin (Fig.
4 J-K), Stranglacunae are particularly long and osteocytes are present, though rare, in
all growth lamellae (Fig. 4 H, M). The system of main vascular canals is less developed
in N. cf. amplifica, and only narrow ascending and radial canals were observed.
Nostolepis elegans (Brotzen) 1934
Fig. 5 A-M
1934 Diplacanthoides elegans; Brotzen, pl. 1, fig. 11 a-c.
Diplacanthoides insignis; Brotzen, pl. 2, fig. 1 a-b.
? Diplacanthoides crassus; Brotzen, pl. 1, fig. 16 a-b.
1937 ? Diplacanthoides unguiparatus; Lehman, pl. 2, fig. 30.
? Diplacanthoides trilobatus; Lehman, pl. 2, figs 31; pl. 4, figs 64.
Diplacanthoides elegans; Lehman, pl. 3, fig. 57.
non 1980 Nostolepis arctica; Vieth, pl. 5, figs 1-9.
1998 Nostolepis striata; Valiukevicius, pl. 1, fig. 2 a-b.
1999 a Nostolepis arctica; Vergoossen, figs 2-4.
1999 b Nostolepis striata, ‘elegans’ form group; Vergoossen, pl. 2, figs 15-17.
2002 a Nostolepis striata; Vergoossen, fig. 59.
2002 b Nostolepis striata; Vergoossen, fig. 36.
2002 c Nostolepis striata, ‘elegans’ form group; Vergoossen, figs 93-99.
Holotype. Brotzen 1934 a: pl. 1, fig. 11 a-c; a flank scale.
Type horizon. The Lower Devonian erratics of the Baltic basin.
Range. From Upper Silurian, Ludlow Series to Lower Devonian, Lochkovian.