Bothriolepis, Eichwald, 1840

Lukševičs, Erwin, 2001, Bothriolepid antiarchs (Vertebrata, Placodermi) from the Devonian of the north-western part of the East European Platform, Geodiversitas 23 (4), pp. 489-609 : 594-595

Bothriolepis sp. indet. 1

( Figs 77 ; 78 )

MATERIAL EXAMINED. — IEC LP 12-6, a Prm; IEC LP 23-45, anterior part of the AVL; LP 32-1, 23-14, 2 Pn and Nu; IEC LP 23-37, prelateral plate; several fragmentary bones of the trunk armour.

LOCALITY AND HORIZON. — Quarry and mines not far from Zarubino village approximately 25 km SE from Lyubitino town, Novgorod region, Russia; upper Famennian.

DESCRIPTION

IEC LP 12-6 is a relatively large Prm with typical reticulate ornamentation ( Fig. 77A, B ). It is strongly vaulted both in longitudinal and transverse directions. The plate is broader than it is long, maximum breadth (32.4 mm) exceeds the length (30.4 mm). The gently convex rostral margin with weakly defined rostral angle is about 1.4 time longer than the wavy orbital margin, which bears the clearly defined nasal notches. The infraorbital sensory groove (ifc1) crosses the lateral margin about a fourth of plate length from the rostral margin, but then strongly curves posteriorly and meets the supraorbital canal (soc) behind the middle of the plate. The preorbital recess is of trifid type.

The Nu IEC LP 23-14 ( Figs 77C ; 78A ) is moderately broad as it is preserved, bears the moderately broad obtected nuchal area and well-defined right lateral margin. The plate is broadest across the lateral corners. The posteri- or margin is almost straight and possess no posterior process. The central sensory line groove is clearly distinct.

The Pn ( Figs 77D ; 78 B-D) is of moderate breadth, L/B index 80-96. The lateral division of the Pn is relatively narrow composing 48% of the general breadth of a plate. The posterolateral corner of otico-occipital depression (pr.po) is rounded and extends laterally over the middle of the Pn’s posterior margin.

The AVL IEC LP 23-45 ( Fig. 77E ) is of moderate breadth as it is preserved. The subcephalic division seems to be relatively short. The anteri- or lateral corner of subcephalic division is situated laterally from the middle between the median and lateral margins; it is developed into a short process. Fragmentary MxL and PVL show a well-developed keel on the dorso-lateral and ventro-lateral ridges.

The ornamentation is reticular, consisting of large pits and quite coarse anastomosing ridges.

REMARKS

All specimens from Zarubino locality, collected by amateur collector, were grouped together because of typical reticular ornamentation with large pits between ridges.

Bothriolepis sp. indet. 1 resembles Bothriolepis ciecere in several features: 1) shape and proportions of the Prm; 2) proportions of the Pn; 3) the position of the postero-lateral corner of otico-occipital depression; 4) similarly strongly defined dorso-lateral and ventro-lateral ridges on the trunk armour; 5) similar ornamentation, but differs in other shape of the Nu and Pn, as well as in more strongly arched Prm.

Figures

FIG. 77. — Bothriolepis sp. indet. 1; A, B, Prm IEC LP 12-6 in dorsal and visceral view; C, fragmentary Nu IEC LP 23-14; D, Pn IEC LP 23-1; E, anterior part of the AVL IEC LP 23-45 in ventral view; F, G, prelateral plate IEC LP 23-37 in dorsal and visceral view. Quarry near Zarubino village, Novgorod region, Russia. Upper Famennian. Abbreviations: AVL, anterior ventro-lateral plate; Nu, nuchal plate; Pn, paranuchal plate; Prm, premedian plate. Scale bars: 5 mm.

FIG. 78. — Bothriolepis sp. indet. 1; A, reconstruction of the Nu IEC LP 23-14; B, Pn IEC LP 23-1; C, D, Pn IEC LP 23-46 in vis- ceral and dorsal view. Quarry near Zarubino village, Novgorod region, Russia. Upper Famennian. Abbreviations: Nu, nuchal plate; Pn, paranuchal plate; cr.pm, paramarginal crista; cr.tv, transverse nuchal crista; csl, central sensory line groove; d.end, opening of canal for endolymphatic duct; ifc1, principal section of infraorbital sensory line; mp, middle pit-line groove; nm, obtected nuchal area; ood, otico-occipital depression. Scale bars: 5 mm.