Grossilepis spinosa ( Gross, 1942 )

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 : 598

Grossilepis spinosa ( Gross, 1942) ( Fig. 81 )

Bothriolepis spinosa Gross 1942: 418-420 , abb. 9A-D.

Grossilepis (?) spinosa (Gross) – Stensiö 1948: 615.

HOLOTYPE. — Nu kept in SMNH. MATERIAL EXAMINED. — The specimens described and illustrated by Gross (1942), kept at SMNH.

LOCALITIES AND HORIZON. — The type locality is an outcrop containing red-grey sandstone at the right bank of Imula River near Ģenduļi and Bienes hamlets, Latvia. Some specimens were collected from the Velna Ala site at the left bank of Abava River. The middle Frasnian Ogre Formation.

DIAGNOSIS. — A small bothriolepidoid with estimat- ed length of dorsal wall of trunk armour reaching about 6 cm. Nu is moderately wide with B/L index of 62 in holotype, with convex posterior margin bearing the sharp median process, shallow postpineal notch on the anterior margin, slightly pronounced posterolateral corners and well-defined lateral corners. Clearly defined lateral corner is slightly pronounced. Lateral spines of ML2 are strikingly long and pointed. Ornament consists of numerous closely and irregularly set tubercles.

DISCUSSION

Grossilepis spinosa resembles Grossilepis tuberculata by several features, but could be readily distinguished from it in its 1) other shape of the Nu and its posterior margin; 2) character and shape of strongly developed long lateral spines of the proximal segment of pectoral fin. Grossilepis spinosa differs well from G. brandi in its relatively narrower Nu and a proportions of the anterior and posterior divisions of the lateral margin of this plate.

REMARKS

This species was established by Gross (1942) as belonging to the genus Bothriolepis , but Stensiö (1948) suggested it is fairly close to Grossilepis tuberculata . Grossilepis spinosa shows some features characteristic for the genus Grossilepis as the shape of the AMD, sutural connections between the AMD and MxL, as well as tuberculate ornamentation.

Figures

FIG. 81. — Grossilepis spinosa (Gross, 1942); A, Nu; B, fragmentary La; C, anterior part of AMD in ventral view; D, ML2. From Gross 1942: abb. 9A-D. Imula River near Lankserde hamlet, Latvia. Ogre Formation. Abbreviations: AMD, anterior median dorsal plate; ML2, lateral marginal plate 2; La, lateral plate; Nu, nuchal plate.